Annex 1 Final Soil Material Investigation Report

Ethiopian Maritime Affairs Authority (EMAA) Beza Consulting Engineers Plc

Soil &Materials Investigation Report

Demand analysis, detail design preparation, supervision and July 2019 Contract admminstration of Modjo Green logistics Hub expansion project Page 1




Table of Contents CHAPTER–1........................................................................................................... 6 INTRODUCTION ..................................................................................................... 6 1.1. BACKGROUND ............................................................................................................................6 1.2. PROJECT LOCATION ..................................................................................................................7 1.3. METOROLOGICAL INFORMATION.........................................................................................8

1.4. GEOLOGY OF THE PROJECT AREA ........................................................................................8 1.5. SCOPE OF WORKS ......................................................................................................................9 CHAPTER–2......................................................................................................... 11 IN-SITU SUB GRADE MATERIAL INVESTIGATION ................................................ 11 2.1 FIELD SRUVEY ..........................................................................................................................11 2.1.1 SURFACE CONDITIONS .........................................................................................................11

2.1.2 SUBSURFACE CONDITIONS .................................................................................................12 2.1.3 TEST PIT AND SAMPLING .....................................................................................................18

2.1.4 DYNAMIC CONE PENETROMETER TEST (DCP TESTING) .............................................19

2.2 INTERPRETATION OF TEST RESULTS .................................................................................20 2.2.1 LABORATORY TEST RESULT ANALYSIS ..........................................................................20 2.2.2 FIELD DCP RESULT ANALYSIS............................................................................................27

2.2.3 PROBLEMATIC SUBGRADE SOIL AND TREATMENT MEASURES ...............................31 2.2.4 DETERMINATION OF DESIGN SUBGRADE STRENGTH .................................................33 CHAPTER–3......................................................................................................... 35 DEEP GEOTECHNCIAL INVESTIGATION .............................................................. 35 3.1 GENERAL ...................................................................................................................................35 3.1.1 SEISMICITY OF THE PROJECT AREA .................................................................................36

3.1.2 SITE GEOLOGY ........................................................................................................................36

3.2 FIELD INVESTIGATION ...........................................................................................................37 3.2.1 CORE DRILLING ......................................................................................................................37 3.2.2 DESCRIPTION OF GEOTECHNICAL LAYER ......................................................................40

3.2.2.1 Layer-I: Light to Dark Brown Clay (0.00 to 3.45 m) ........................................................40 3.2.2.2 Layer-II: Dark to Light Brown Silty CLAY Soil (3.45 to 6.45 m) ...................................40

3.2.2.3 Layer-III: Brown Silty CLAY (6.45 to 9.45m) .................................................................40 3.2.2.4 Layer IV: Light Brown Silty CLAY (9.45 to 13m) ...........................................................40

3.2.2.5 Layer IV: Silty Clay with Some Sand (13m to 20m) ........................................................41 3.2.3 STANDARD PENETRATION TEST (SPT) (ASTM D1586) ..................................................41 3.2.4 GROUND WATER LEVEL MEASUREMENT (ASTM D6000) ............................................45 3.3 LABORATORY TESTS ..............................................................................................................45

3.3.1 BULK UNIT WEIGHT () .........................................................................................................45

3.3.2 SPECIFIC GRAVITY (GS) (ASTM D854 – 14) .......................................................................45

3.3.3 WATER CONTENT DETERMINATION (%) (A5TM D 2974-87) ......................................45

3.3.4 SIEVE ANALYSIS (ASTM C136 / C136M – 14) .....................................................................46 3.3.5 CHEMICAL TEST OF SOIL .....................................................................................................46 3.3.6 ATTERBERG LIMIT TESTS (ASTM D4318 - 17E1) ..............................................................46

3.3.7 UNCONFINED COMPRESSION STRENGTH TEST (UCS TEST) (ASTM D2166 ..............46 3.3.8 DIRECT SHEAR STRENGTH TEST (DSST) (ASTM D3080 / D3080M – 11) ......................46 3.4 BEARING CAPACITY OF SOIL ...............................................................................................47




3.4.1 BEARING CAPACITY OF SOILS BASED ON LABORATORY RESULT ..........................47 3.4.2 BEARING CAPACITY OF SOILS BASED ON FIELD SPT N- VALUES ............................50 3.4.3 SETTLEMENT ANALYSIS ......................................................................................................52 3.5 RETAINING STRUCTURES ......................................................................................................52 CHAPTER–4......................................................................................................... 53 LOCATION AND TESTING OF CONSTRUCTION MATERIALS ................................. 53 4.1 GENERAL ...................................................................................................................................53 4.2 GRAVEL BORROW SOURCE INVESTIGATION ...................................................................55 4.3 ROCK QUARRY SOURCES ......................................................................................................58

4.4 NATURAL SAND SOURCES ....................................................................................................61 4.5 WATER SOURCES FOR CONSTRUCTION ............................................................................64 CHAPTER–5......................................................................................................... 65 CONCLUSIONS AND RECOMMENDATIONS ........................................................... 65 5.1 CONCLUSION ............................................................................................................................65 5.2 RECOMMENDATIONS .............................................................................................................66




LIST OF FIGURES

Figure 1.1: Satellite Image of dry port (Location of map)…………………….……6

Figure1.2: Geological map of the area ……………………………………………8

Figure-2.1: Partial view of hub expansion area………………………….………11

Figure -2.2: Erosion gullies within the expansion area…………………………….11

Figure 2.3: Test pit excavation……………………………………………………12

Figure 2.4: DCP Testing in Progress……………………………………………….18

Figure 2.5: Variation of Plasticity index (%) of the sub grade soils @1-2m depth.20

Figure 2.6: Plasticity index (%) of the sub grade soils at variable depth………....21

Figure 2.7: Variation of Plasticity index (%) of the subgrade soils 2-6m depth….22

Figure2.8: A-Line chart of the sub grade soils…………………………………….23

Figure2.9: Variation of Maximum Dry Density of soil at variable depth....……….24

Figure2.10: Variation of Optimum Moisture Content of soil at variable depth........24

Figure2.11: Variation of subgrade soil CBR at 95% MDD…………………….….25

Figure2.12: Variation of CBR-swell of subgrade soil……………………………...26

Figure 2.13: Laboratory test on progress @ BCE central Laboratory…………….26

Figure2.14: In-situ CBR values @ ground level……………………………………28

Figure2.15: In-situ CBR values @ 2m level…………………………………….….28

Figure2.16: In-situ CBR values @ 3m depth………………………………………29

Figure2.17: In-situ CBR values @ 4m depth……………………………………....29

Figure2.18: In-situ CBR values @ 5m depth………………………………………30

Figure 2.19: In-situ CBR values @ 5-6m depth……………………………………30

Figure2.20: In-situ CBR values @ 6-7m depth…………………………………….31

Figure 3.1: Location of the boreholes with respect to the site map……………….38

Figure 3.2: Core Drilling Process on the project Site………………………………39

Figure 3.3: Sample photos of Borehole boxes…………………………………….39

Figure 4.1: Natural gravel source at Melmele kebele…………………………….57

Figure 4.2: Rock quarry source within the compound (Q1)………………………..59

Figure 4.3: Rock quarry Source 11.8Km towards Debrezeit (Q2) …………...…...60

Figure 4.4: sieve analysis of natural sand sources …………………………….….63




LIST OF TABLES

Table 1.1: Monthly Mean Maximum and Minimum Temperature of Modjo town…...7

Table 2.1: In situ material Description on trial test pits……………………………12

Table 2.2: Statistical summary of DCP- CBR’s value ……………………………...27

Table 2.3: Design Subgrade strength of Test Pits…………………………………33

Table 3.1: Bedrock Acceleration Ratio αo……………………………………...…36

Table 3.2: Summary of geological formation of the site………………………….36

Table 3.3: Location of boreholes………………………………………………….38

Table 3.4: Measured and adjusted SPT N-Values for the project………………...42

Table 3.5: Bearing Capacity of Selected depths………………………………….47

Table 3.6: Allowable bearing pressure (kPa) based on SPT at depth of 2.5m…...51

Table 4.1: Description of borrow source………………………………………….55

Table 4.2: The tests to be carried out on natural gravel source samples…………56

Table 4.3: Summary of test result of Natural gravel sources……………………...56

Table 4.4: Tests to be carried out on the rock sample…………………………….58

Table 4.5: Summary of Rock Quarry source ……………………………………...59

Table 4.6: Test result and requirements for rock aggregate……………………...61

Table 4.7: Test result and requirements for natural sand source …………………63

LIST OF ANNEXES

Annex – I Test Pit logs of subgrade soil

Annex – II DCP Test and analysis,

Annex – III Summary of Laboratory test Results of subgrade soil and

construction materials

Annex – IV Summary of Boreholes laboratory test Results and

Annex – V Boreholes logs




CHAPTER–1

INTRODUCTION

1.1. BACKGROUND

The Government of the Federal Democratic Republic of Ethiopia, represented

by the Ethiopian Martime Affairs Authority(EMAA) has been allocated grant

funds from the World Bank towards consultancy services for demand

analysis, detail design preparation, supervision and contract administration

of Modjo green logistics Hub expansion project.

Ports are well known as playing an important role in multimodal transport

systems and international supply chains, apart from their traditional role as

clusters of economic activities. Ports engage in various activities:

loading/discharging cargo onto/from vessels; providing value- added

services such as labeling, packaging, cross-docking, and others; and acting as

warehouse and distribution centers (World Bank, 2007). Ports add more

value to shipments that are in the port area by further integrating themselves

into value chains. Many ports are increasingly being perceived as integrated

and inseparable nodes in their customers’ supply chains. Ports play a critical

role in the effective and efficient management of this industry.

In the move to cater for an ever increasing volume of import-export goods in

a coordinated way, the government of Ethiopia has taken a strategic

measure by improve development of the dry port at several locations in the

country, Modjo dry port expansion being one of them.




1.2. PROJECT LOCATION

Modjo dry port is located in the eastern Shewa zone at Lome woreda of the

oromia regional state , nearly 75 km East of Addis Ababa, it has a latitude

and longitude of N8°34'25.89880"E39°09'11.34467". Modjo town has long

been a commercial center of the Eastern Shewa zone .The proposed project

consists of demand analysis, detail design preparation, supervision and

contract administration of Modjo green logistics Hub expansion project.

Figure1.1 depicts the satellite imagery of Modjo dry port.

Figure1.1: Satellite Image of dry port (Location of map)




1.3. METOROLOGICAL INFORMATION

The meteorological information of the area is collected from Meteorological

map of Ethiopia, 1979 edition. In addition to that, recent data were collected

from Modjo meteorological station. The data gathered include, climatic

classification of the area, Rainfall data, and temperature of the project area.

Climatically, the project area is classified as warm temperate climatic zones

and receives a mean annual rainfall of 875mm.

The monthly mean maximum temperature varies from 25.8 0c to 31.20c. the

higher usually recorded from March to April while lower temperature is

recorded from December to January.

Table1.1: Monthly Mean Maximum and Minimum Temperature of Modjo town

1.4. GEOLOGY OF THE PROJECT AREA

Parallel with the geotechnical investigation, the geological condition of the

site and regional geology of the site is always important to study. The project

area is characterized by different rock formations and soils emanating from

weathering of those rocks and transported from neighboring area. According

to the Geological Map of Ethiopia, Mengeshaet.al (1996) and field

observation, the area is covered by Tertiary and Quaternary volcanic,

lacustrine sediments and alluvium. In the main Ethiopian rift the quaternary

sediments are mostly of lacustrine origin. Lacustrine beds are inter-bedded

Temperature Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Maximum Mean.

28.6 29.6 30.2 30.5 31.2 28.7 26.3 25.8 27.6 28.4 28.4 27.8

Minimum Mean.

9.50 10.5 12.9 13.5 13.6 13.4 13.1 13.2 12.6 11.1 10.1 8.3




with Plio-Pleistocencepyroclastics in the lake region and on the rift shoulders.

The lacustrine beds are mostly re-deposit volcanic sands, tuffs with calcareous

diatomite.

Figure1.2- Geological map of the area

1.5. SCOPE OF WORKS

In order to design heavy duty pavement structures, to locate suitable

construction materials for the pavement works and to assess geotechnical

hazards at green logistics hub expansion project, a full materials and

geotechnical investigation work were carried out within Modjo green logistics

hub expansion project.

Project area




The scope of investigations included:

Subsurface soil Investigation: - this includes conducting borehole

investigation, Dynamic Cone penetration tests (DCPs) and

exploration of trial test pits.

Borrow sources Investigations: - this involves exploration of borrow

sources location, excavation of trial test pits and collect material

for laboratory.

Quarry sources Investigations: - this involves identification of rock

sources and hand pick rock samples from sources for laboratory

testing.

Sand and Water sources: - this involves identification sources and

collect sample from the sources.




CHAPTER–2

IN-SITU SUB GRADE MATERIAL INVESTIGATION

2.1 FIELD SRUVEY

General site condition assessment was carried out visually, through datum

location, GPS recordings, test pit excavation, DCP surveys and basic soil

characteristic evaluation. The in-situ subgrade material investigations were

carried out in January 2019. The formation of subgrade material is

influenced by the geology of the area. A general description of the geology

is presented in section 1.4 of the report.

The following sub-sections provide a summary of the surface and subsurface

conditions encountered during the investigation.

2.1.1 SURFACE CONDITIONS

The ground surface at propose Modjo green logistics hub expansion area is

dominantly rolling and flat terrain with some mountainous terrain near to the

existing rail yard section. Erosion gullies up to 3m depth is observed at

several location within the proposed expansion area. The in-situ material

within the proposed expansion area is predominantly thick layer of clay to

silty clay soil soil formation but thickness of 3m depth rock out crop were

observed around the west north direction on existing rail yard. Vegetation

within surrounding is primarily limited to short grass, small bushes and

scattered trees grow.

There is huge amount of waste/spoiled material (from existing construction

works) on the proposed port development area, which needs to be removed

by the contractor during construction.




2.1.2 SUBSURFACE CONDITIONS

The subsurface investigations on the expansion area are conducted by

exploration of trial test pits extended up to 4.5m and borehole investigation

extended up to 20m. As per the investigation , the in-situ material on the

project area is predominantly of Light to dark clay Soil, dark to light Brown

silty clay soil, Brown silty clay, Light Brown Silty clay soil and Silty clay with

some Sand. But limited thickness of weathered rock outcrops was observed at

near the existing rail yard. In all the trial pits and boreholes, no ground

water was encounter within the depths.

Total of 40 trial test pits and 14 boreholes were investigated within

expansion area from January to February 2019. The test pits were dug at

an average of 100m length interval. The locations are shown on table 2.1.

The soil profiles were logged and disturbed soil samples were collected for

Figure -2.2: Erosion gullies within the

expansion area

Figure-2.1: Partial view of hub

expansion area




laboratory testing. Material description of each trial test pits are presented

in table 2.1.

Table2.1 In situ material Description on trial test pits

Test Pit

GPS (E,N) Depth (cm) Material Description

TP-1 0516605, 0948821

0-20 Light brown medium stiff clay soil

20-100 brown medium stiff clay silt soil

100-200 light brown medium stiff clay silt soil mixed with little gravel

TP-2 0516673, 0948916

0-30 light brown medium stiff silt clay soil

30-100 brown stiff sand silt clay soil

100-200 Reddish to brown stiff, medium dry sand silt clay soil mixed with gravel

TP-3 0516731, 0949012

0-20 brown sandy silt clay soil

20-40 dark brown clay silt soil

40-100 brown stiff silt clay soil

Figure 2.3: Test pit excavation




100-200 light brown stiff, medium dry silty clay sand soil

TP-4 0516765 ,0948848


30-100 loose black brown moist clay silt soil

100-200 light brown silt clay sand soil

TP-5 0516847, 0948939

0-40 light brown to light gray medium stiff, dry silt clay sand soil

40-100 brown clay silt sandy soil

100-200 brown clay silt soil

TP-6 0517002, 0949011

0-260 gray medium stiff silt clay soil

260-360 light gray silt clay soil

360-460 loose light gray silt sand clay soil

TP-7 0517149, 0948993

0-50 light brown medium stiff ,medium dry silt clay sand soil

50-100 light gray silt clay sand soil with whitish sedmentary gravel material

100-200 whitish to light gray sand silt clay soil

TP-8 0517024, 0948812

0-30 light gray spoiled soil

30-100 natural soil ,black moist clay silt soil

100-200 light gray clay silt sand soil

TP-9 0516877, 0948838

0-80 dark brown medium stiff, medium dry clay silt soil

80-140 light gray medium stiff ,medium dry sandy silt clay soil with few gravel

140-200 light gray sand silt clay soil with few gravel material

TP-10 0516734, 0948748

0-20 light brown medium stiff clay silt soil

20-100 black medium stiff clay soil

100-200 light brown medium stiff moist clay silt soil

TP-11 0516467, 0948657

0-40 Light brown to gray clay silt soil

40-100 black clay soil

100-360 light brown medium stiff clay silt soil




360-460 light gray medium stiff silt clay soil

TP-12 0516558, 0948618

0-20 light brown to brown clay soil


100-280 brown clay silt soil

280-380 light gray silt clay sand soil

380-480 light gray silt clay sand soil

TP-13 516618, 94875


30-100 black clay silt sand soil

100-200 light brown clay silt soil mixed with few gravel

TP-14 516516, 948755

0-100 dark brown clay soil

100-150 light brown clay silt soil

150-200 light gray medium stiff, medium dry silt clay soil

TP-15 516731, 948670

0-100 dark brown stiff ,dry clay silt sand soil

100-200 light brown stiff, dry clay silt sand soil

TP-16 516875, 948750



TP-17 516531, 948373



TP-18 516648, 948576

0-20 light brown to brown clay soil

20-100 black clay silt soil

100-200 light brown clay soil

200-320 light gray clay soil

320-420 light yellowish gray clay silt soil

420-520 light yellowish gray medium stiff ,medium dry clay silt soil

TP-19 0516910 , 0948615


360-460 dark brown stiff clay silt soil




TP-20 0517010, 0948572


10-100 light gray clay soil

100-200 light brown to light gray clay soil

TP-21 0517089, 0948488

0-100 Light brown clay soil

100-200 light gray clay silt soil mixed with few gravel material

TP-22 0516725, 0948829



100-200 light brown medium stiff clay sand silt soil

TP-23 516719, 948640


100-200 light brown very stiff, dry silt clay sand soil

TP-24 516796, 948582

0-30 brown clay soil

30-110 light brown silt clay sand soil

110-200 light yellowish to light gray very stiff ,dry silt sand clay soil

TP-25 516863, 948525


30-400 light gray clay silt sand soil

400-500 loose light gray ,moist silt clay sand soil

500-600 loose light gray moist clay silt sand soil

TP-26 0516743, 0948458


400-450 loose dark gray medium dry clay silt sand soil

450-500 light gray to light brown medium stiff, medium dry silt sand clay soil

500-600 light gray silt sand clay soil

TP-27 0516893, 0948411


50-250 light gray to light brown clay silt soil

250-400 light gray medium stiff, medium dry silt clay sand soil

TP-28 0516498, 0948245

0-240 brown medium stiff, medium dry clay silt sand soil

240-440 light brown moist clay silt soil




TP-29 0516568, 0948109

0-50 brown stiff ,dry clay silt soil

50-110 light brown stiff, dry clay silt soil

110-200 brown stiff, dry clay silt soil mixed with few gravel material

TP-30 0516974, 0949078

0-90 light brown medium stiff, dry clay silt sand soil

90-150 light gray to whitish stiff ,dry clay silt sand soil mixed with gravel material


TP-31 0516952, 0948968

0-50 dark brown clay sand gravel material

50-120 light brown clay silt mixed with gravel material

120-200 light brown medium stiff, medium dry clay silt soil

TP-32 0516675, 0948504


20-110 black to brown clay soil

110-200 brown clay soil with few gravel material

TP-33 0516480, 0948022


30-120 brown clay soil


TP-34 0516788, 0948704

0-90 dark brown medium stiff, medium dry clay soil

90-200 light brown silt clay soil

TP-35 0516849, 0949128

0-80 light red to light gray dry clay silt soil with few gravel material (can be as construction material)

80-200 light gray to light brown dry clay silt soil with gravel material (recommended as construction material)

TP-36 0516905, 0949061

0-100 light gray to light brown clay silt soil

100-200 light gray to light brown clay silt soil with gravel material

TP-37 0516399, 0948215

0-130 light brown gray silt clay soil

130-200 light gray sand silt clay soil

TP-38 0516326, 0948030

0-400 light gray sand silt clay soil

400-500 brown clay sand silt soil

TP-39 0516296, 0947971


100-250 Black clay silt soil

TP-40 0516382, 0947922

0-120 dark brown dry silt clay soil





Based on field observations and laboratory test result analysis, it was

concluded that the in-situ subgrade layer cannot provide adequate bearing

strengths and less deformation resistance for design heavy load and

therefore, an improved subgrade layer is required.

2.1.3 TEST PIT AND SAMPLING

To determine the engineering properties and to assess the suitability of the in

situ material within the expansion area ,representative disturbed samples

were collected by digging test pits from each layer of variable soil profiles

hence, more than one samples were taken from each test pit where the soil

profiles exhibit variability. Test pits of approx 1.5 m x 1.5 m size were

excavated to depth up to 4.5m below the actual ground surface.Upon

completion of the pit excavation and sampling, the vertical soil profile of

each test pit was recorded and the test holes then carefully

backfilled,compacted and leveled off to their original level. The collected

samples from test pits were tested at Beza consulting engineer Central

laboratory.The test pit logs are summarized and presented in Annex–I of

report.

The following tests were performed:

Particle Size Analysis (AASHTO T88-90)

Atterberg Limits, LL , PL and LS(AASHTO T89-90 and T90-87)

Moisture-Density Relationship (AASHTO 180-90, Method D)

Four days soaked 3-Point CBR (AASHTO T193)

CBR-swell and

Linear shrinkage limit test




2.1.4 DYNAMIC CONE PENETROMETER TEST (DCP TESTING)

A Dynamic Cone Penetration Survey (DCP testing) was carried out within

propose dry port expansion area at 40 test pits location .The DCP test is a

rapid but continuous assessment of in situ strength of the foundation material.

The in-situ DCP tests were performed during the dry season hence the in-situ

CBR values derived from the DCP testing were greater than laboratory CBR

values . Detailed analysis of DCP field data and interpretation of results are

given in Annex II.

The underlying principle of the DCP test is that the rate of penetration of a

60o steel cone driven by a standard (8kg) hammer freely falling through a

controlled (575mm) drop is inversely related to the strength of the material

as measured by, for example the low rate of DCP penetration resistance is

associated with high strengths material while high rate of penetration is

encountered in weak layers. While conducting the test, in majority of sections

of the road were found appropriate to take reading at increment of with 3

to 10 consecutive blows. DCP testing was carried out using the equipment,

test procedure and data interpretation method as recommended by TRRL

Manual (Road Note 31).

Figure 2.4: DCP Testing in Progress




The DCP penetration rate (mm/blow) has been converted to CBR value using

the standard TRL correlation formula Log10(CBR)=2.48–1.057 x

log10(mm/blow). The UK DCP version 3.1 software which was developed

by TRRL has been used for analysis and delineates the boundaries of various

subsurface strata and computes field DCP data in to layer wise in-situ -CBR

values.

2.2 INTERPRETATION OF TEST RESULTS

2.2.1 LABORATORY TEST RESULT ANALYSIS

In order to design heavy duty pavement structures of Modjo Green Logistics

Hub expansion , the in-situ sub grade material lies within of 3000 mm depth

below finished design sub grade level were properly analyzed since it is

critical to pavement structure to perform satisfactorily.

In general, the subgrade layer is required to resist repeated stressing by

heavy duty traffic and to be stable to the stresses imposed by varying

climatic and moisture influence. For the pavement design purpose, the in-situ

sub grade material within the infulence depth has been analyzed in

accordance with the procedures given in different design manuals. As

recommended in the design manuals the roadbed formation will be re-

compacted to 95% of BS Heavy compaction density in order to ensure that a

high level of subgrade support is obtained.

As a matter of interest the subgrade material were also classified in

accordance with the average in-situ-CBR values derived from the DCP tests

at full depth. This will give an alternative indication of uniformity and in-situ

strength of the layer. Apart from the uniform ground level; deteroration of

ground(erosion gully) were encountered in any of the test pits which were

samples were collected from a depth of approximately more than 4m.




As per the test result, the in-situ material is predominantly fine grained soils

but few sections had coarse grained soils. The fine grained soils of silty clay

and clay soil had high plasticity with Liquid Limit values ranging from 0% to

98% and Plasticity index values ranging from 0% to 46%.The variation of

Plasticity of subgrade soil is presented in figure 2.5 below.

Figure 2.5: Variation of Plasticity index (%) of the sub grade soils @1-2m depth

0

10

20

30

40

50

60

70

80

90

100

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39

Pla

stic

ity

Val

ue

s (%

)

TP-No.

Varation of Plasticity of Sub grade soil

LL

PI

UL LL

UL PI




0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40

LL @1-2m

PI @1-2m

LL @2-3m

PI @2-3m

LL @3-4m

PI @3-4m

LL @4-5m

PI @4-5m

LL @5-6m

PI @5-6m

LL @6m

PI @6m

UL LL

UL PI

TP-No.

0

10

20

30

40

50

60

70

80

90

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39

Pla

stic

ity

Val

ue

s (%

)

Station TP-No.

Plasticity of subgrade soil

LL

PI

UL LL

UL PI

Figure 2.6: Plasticity index (%) of the sub grade soils at variable depth

Figure 2.7: Variation of Plasticity index (%) of the subgrade soils 2-6m depth




0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100 110

Pla

stic

ity

Ind

ex

(%)

Liquid Limit

A-Line Chart for Sub grade soil

A-line

The plasticity chart helps to classify the type of soils based on their plasticity

characteristics (i.e. Atterberg Limits and Indices of soils). Generally, materials

falling above the A-Line are classified as clays and below the A-Line are

classified as silts or gravel. A-line plot shown in Figure below indicates that

the predominate samples from expansion area have been found above the

A-line plotting which again confirmed that the material has high plastic fine

grain soil.

Figure2.8: A-Line chart of the sub grade soils

Soil samples collected from trial pits have been compacted in the laboratory

at various moisture contents to derive a dry density versus moisture content

relationship.The Maximum Dry Density (MDD) and optimum moisture content

(OMC) of subgrade soil samples on Modjo green hub project graphically

presented in Figure 2.9 below: As per the test result, the MDD and OMC

values of sub grade material over variable depth ranged from 1.36 to

1.86g/cm3 and 12% to 36% respectively but in majority section the MDD

value >1.42g/cm3 and OMC value > 14.0%.




1.30

1.40

1.50

1.60

1.70

1.80

1.90

0 5 10 15 20 25 30 35 40

MDD (g/cm3)1mMDD (g/cm3)2-3mMDD (g/cm3)3-4mMDD (g/cm3)4-5m

MDD of Subgrade soil at variable depth

Test pit

MD

D (

g/c

m3)

Figure2.9: Variation of Maximum Dry Density of soil at variable depth (T180

Compaction)

Figure2.10: Variation of Optimum Moisture Content of soil at variable depth

(T180)




0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40

CBR at95%MDD

Min CBR

Variation subgrade soil CBR @95%MDD

Test pit no.

Four days soaked three point CBR test in accordance with AASHTO T-193

was carried out on disturbed soil samples recovered from test pits to

determine the strength of the sub grade material. CBR-swell test also

conducted to evaluate potential expansiveness of the material.

The shear strength of a material is closely related to the material

classification. The CBR results therefore follow the trend of the material

classifications. For fine grained of clay and silt clay soil have low CBR values

and have high CBR swell. Isolated higher CBR values are encountered at few

test pits as shown in Figure 2.11 below. As per the test result, about 85% of

the total sub grade samples of expansion area have CBR strengths value less

than 5% and these can be classified as unsuitable soil hence it needs

replaced with selected suitable material.

Figure2.11: Variation of subgrade soil CBR at 95% MDD




0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40

CBR-swell of subgrade soil.

Av. swell(%)

SwellLimit

Test pit

The amount of CBR-swell also determined on disturbed samples of soil

recovered from test pits to evaluate potential to heave of the material. As

per the test result predominate sub grade soil samples have CBR-swell value

of greater than 3% .These soil could be potentially expansive and have low

bearing strength. The CBR-swell values of subgrade soil samples graphically

presented in Figure below. The summary of the subgrade soil test result is

given in Annex-III of the report.

Figure2.12: – Variation of CBR-swell of subgrade soil

Figure 2.13: Laboratory test on progress @ BCE central Laboratory




2.2.2 FIELD DCP RESULT ANALYSIS

DCP testing was carried out using the equipment, test procedure and data

interpretation method as recommended by TRRL Manual (Road Note 31). The

UK DCP version 3.1 software which was developed by TRRL has been used

for analysis and delineates the boundaries of subsurface strata and computes

field DCP data in to layer wise in-situ-CBR values.

The DCP tests were carried out to obtain the in-situ strength of the subgrade

soil within the expansion area. The DCP-CBR’s are usually higher than the

laboratory CBR results .The statistical in-situ CBR values derived from the DCP

testing are summerized in the table 2.2 below.

Table2.2: Statistical summary of DCP- CBR’s value

Parameters

DCP – CBR values over the influence depth.

Ground Level

1-2m Depth

2-3m Depth

3-4m Depth

4-5m Depth

5-6m Depth

6-7m Depth

Average Value 12.2 17.7 18.5 11.9 13.6 9.3 13.5 Maximum Value 27 37 40 21 45 19 19 Minimum Value 1 3 2 1 2 3 8 90th Percentile 22.1 29 27.6 19.6 25.8 16.6 17.9

Median 10.5 19 19 12.5 7 7.5 13.5

The summary of DCP test result is given in Annex-II of the report

The distribution DCP-CBR Value at variable depth are presented through

Figure 14 to Figure 20




0

5

10

15

20

25

30

0 5 10 15 20 25 30 35 40

Insitu CBR Value @ Ground Level

DCP-CBR%

DC

P-C

BR

%

Test Pit No.

0

5

10

15

20

25

30

35

40

0 5 10 15 20 25 30 35 40

Insitu CBR value @ 1-2m Depth

DCP-CBR

DC

P-C

BR

%

Test Pit No.

Figure2.14: In-situ CBR values @ ground level

Figure2.15: In-situ CBR values @ 2m level




0

5

10

15

20

25

30

35

40

45

0 5 10 15 20 25 30 35 40


DCP-CBR

DC

P-C

BR

%

Test Pit No.

0

5

10

15

20

25

0 5 10 15 20 25 30 35 40


DCP-CBR%

DC

P-C

BR

%

Test Pit No.

Figure2.16: In-situ CBR values @ 3m depth





0

5

10

15

20

25

30

35

40

45

50

0 5 10 15 20 25 30 35 40


DCP-CBR%

DC

P-C

BR

%

Test Pit No.


Figure 2.19: In-situ CBR values @ 5-6m depth

0

2

4

6

8

10

12

14

16

18

20

0 5 10 15 20 25 30 35 40


DCP-CBR%

DC

P-C

BR

%

Test Pit No.




Figure2.20: In-situ CBR values @ 6-7m depth

2.2.3 PROBLEMATIC SUBGRADE SOIL AND TREATMENT MEASURES

By virtue of their unfavorable properties, sub-grade materials fall into the

category of “Problem Soils” and, when encountered, will normally require

special treatment before acceptance as a pavement foundation. Thick

formation of clay and clayey silty soil have been predominately found on

the project area. The test result indicate that,these soil are potentially

expansive and have low bearing strength( i.e, which is characterized by

LL>60 or PI>30 or CBR <5% or CBR-swell>2%).

As per the analysis , about 85% of subgrade soil on the port expansion

section is unsuitable material and hence it needs to excavate the unsuitable

subgrade material within the infulence depth and replaced with selected

material (specified in borrow source section). The depth of replacment for

capping layer depends on CBR value (for CBR 1%, 2%, 3%, 4% replacment

depths are 900mm,600mm,400mm and 250mm respectively).

While carrying out the replacement activity, the excavated bed shall be

exposed to sun and wind causing loss of moisture. This would initiate volume

0

2

4

6

8

10

12

14

16

18

20

0 5 10 15 20 25 30 35 40


DCP-CBR%

DC

P-C

BR

%

Test Pit No.




reduction in the surrounding soil, which becomes prone to attract suction

generated moisture during wet season. Such rise in the moisture would

aggravate the differential swelling along the profile. Scarify or loosen about

250 mm from the new roadbed level reached after excavation for

replacement, and recompact the loosened soil on wetter side of the OMC

(Optimum Moisture Content established from the density – moisture relation on

the bed soil). It is proposed to recompact the roadbed below replacement

level not more than OMC +2% moisture in accordance with the requirements

of AASHTO T-180 (heavy compaction). This partly compensates the loss of

moisture on excavation and also helps achieve a reasonable level of moisture

in the roadbed precluding excessive ingress of moisture later during the wet

season. The capping or fill material shall not contain particles more than two-

third of the specified layer thickness, any compacted layer shall be not be less

than 100mm or more than 200mm. Each layer shall be compacted to

minimum of 97% of maximum dry density in accordance with the requirements

of AASHTO T-180 (heavy compaction), however the scarified layer shall be

compacted to minimum of 100%MDD (light compaction).




2.2.4 DETERMINATION OF DESIGN SUBGRADE STRENGTH

As per the analysis of test results discussed in the above sections, the

predominant sub grade soil class of modjo logistics green hub is weak

subgrade soil ( i.e about 85% of the test pit have CBR values below 5%).

For pavement design purposes it is important to consider that the strength of

the subgrade is not seriously underestimated for large areas of pavement or

overestimated to such an extent that there is a risk of local failures.

Therefore, the best compromise for design purposes is to use the lower CBR

value of within each design depth or the lower depth CBR value. But if the

lower depth of CBR is much greater than the upper depth it was taken as

average of them to be safe. The laboratory CBR values of each test pit

interms of depth and the recommended CBR values are presented in the

shown table.

Table2.3: Design Subgrade strength of Test Pits

TP No.

Depth (m)

CBR value (%)

Recommended design CBR of

pits (%)

TP No.

Depth (m)

CBR value (%)

Recommended Design CBR of

pits (%)

1 1 4.7

2 21 1 1.6

3 2 2 2 2.6

2 1 1.3

1 22 1 0.3

1 2 1.2 2 0.4

3 1 3

2 23 1 1.9

2 2 1.5 2 1.5

4 1 1.7

2 24 1 0.3

5 2 1.7 2 9.4

5 1 0.4

1 25 5 1

2 2 1.1 6 2

6 4 23

12 26 5 3

3 5 9 6 3

7 1 2.3 15 27 3.5 2.9 5




2 28 5 5

8 1 0.7

2 28 3.5 2

1 2 2.3 5 1

9 1 1.8

1 29 1 3.8

5 2 0.3 2 5

10 1 0.5

2 30 1 2.8

4 2 2.2 2 3.6

11

1 2.8

1

4 0.7 31

1 7.2 4

5 1 2 4

12

1 0.3

1 32

1 2.7 2

4 1.1 2 2.4

5 1 33

1 1.9 10

13 1 0.5

1 2 19.5

2 3 34

1 0.3 1

14 1 0.2

1 2 1

2 0.4 35

1 18.5 18

15 1 1.5

3 2 18.5

2 2.7 36

1 2.3 7

16 1 0.8

1 2 7

2 1.2 37

1 2.3 3

17 1 14

1 2 3.5

2 1.2 38

6

3

3

18 5 1

1 6 4

39 1 0.4

2 19 5 2 2 2 2.5

20 1 2.2

2 40 1 2

1 2 1.8 2 1




CHAPTER–3

DEEP GEOTECHNCIAL INVESTIGATION

3.1 GENERAL

A deep geotechnical investigation was carried out to determine geological

conditions of Modjo Green logistics Hub expansion project and foundation

conditions at the buildings and ware house area. A detailed investigation

with core drilling in 14 Boreholes were done on the project site. Most of the

boreholes were done up to an average depth of 18m, where the minimum

depth of 15m and the maximum is 20m. Both disturbed and undisturbed

samples were collected for laboratory tests. Ranges of laboratory test have

hence interpreted. The geotechnical investigation work was carried out in

very close cooperation with the materials investigation. Geotechnical

investigation (borehole drilling) was not carried out at the cut sections (north

side of the project) and location of accumulated material (from existing

construction), thus it is recommended to investigate during construction phase.

The purpose of deep site investigation is to determine the existing soil

profiles and engineering characteristics of the subsurface conditions at the

expansion site and to provide :

• Subsurface profile (type and thickness/extent) of layers;

• Ground water location (if encountered with the vicinity of the

recommended drilling depth)

• Geotechnical design parameters such as the soil bearing capacity,

expected foundation settlement, side slope stability, hydrological

conditions which will be required for a safe , economic design and

excavation of the engineering works, at the site and other special

recommendation.




• Methods of construction, site seismicity characters, groundwater

conditions and quality control requirements.

3.1.1 SEISMICITY OF THE PROJECT AREA

Different areas do have different seismicity zoning according to their vicinity

to seismic effects. In Ethiopia we have 4 common seismic zones. Accordingly,

the project area which is located in Modjo is classified as Zone 4. This hence

needs consideration of seismic effects like from earth quake while designing

different structures in and around this area. It is recommended to follow the

EBCS-8 provisions while working any design in this zone. In this code there

are also Bedrock acceleration factors that we need to stick to.

Table 3.1: Bedrock Acceleration Ratio αo

Zone 4 3 2 1

αo 0.1 0.07 0.05 0.03

3.1.2 SITE GEOLOGY

The geological formation of the specific site can be seen from the results of

the 14 boreholes .In these boreholes the underground profiles of each is

clearly defined to the respective depth. In most of these test location the

geological formation can be summarized as per the following table.

Table 3.2: Summary of geological formation of the site

Depth (m) Geological Formation Remark

0-3.45 Light to Dark Brown Clay Soil

3.45-6.45 Dark to Light Brown Silty CLAY soil

6.45-9.45 Brown Silty CLAY

9.45-13.00 Light Brown Silty CLAY soil

13.00 to 20.0 Silty CLAY with some Sand




The summary in Table 3.2 is a very average classification of the ground and

may not represent to some of the core logs. The exact profiling of each of

the boreholes Logs are attached annex-V of this report.

3.2 FIELD INVESTIGATION

A detailed investigation with rotary core drilling at 14 Boreholes were done on

the project site. Most of the boreholes were done up to an average depth of

18m, where the minimum depth of 15m and the maximum is 20m. Both disturbed

and undisturbed samples were collected for laboratory tests. During the field

investigation, the following activities were facilitated.

Core drilling and collection of all the cored samples;

Collection of undisturbed sample ;

Taking the SPT reading at different intervals;

Checking/ Recording the depth of ground water table (if/ when exists)

3.2.1 CORE DRILLING

A detailed investigation with rotary core drilling at 14 boreholes were done

on the Modjo Green logistics Hub project. The drilling work has been started

on February 4, 2019 and ended on February 25, 2019. The GPS locations

of the BHs where the UTM Adindan Datum was considered are listed in the

following table.




Table 3.3: Location of boreholes

Bore Hole ID

Northing (m)

Easting (m)

Elevation (m), Original Ground Level

Excavated depth (meter)

BH-1 948961 516745 1822 15

BH-2 949052 516383 1840.6 18

BH-3 948883 517026 1815.2 17

BH-4 948823 516662 1819 17

BH-5 948685 516486 1813.8 18

BH-6 948937 517207 1807.4 17

BH-7 948614 516635 1813.1 17

BH-8 948929 516472 1839.2 20

BH-9 948628 516886 1814 16

BH-10 948331 516588 1812 19

BH-11 948328 516895 1812.1 15

BH-12 948470 516702 1811.6 17

BH-13 949018 516094 1825.8 20

BH-15 949059 516906 1817 20

Figure 3.1: Location of the boreholes with respect to the site map




Figure 3.2 Core Drilling Process on the project Site

Figure 3.3: Sample photos of Borehole boxes




3.2.2 DESCRIPTION OF GEOTECHNICAL LAYER

Fourteenboreholes were drilled to investigate study the subsurface condition

of the project. Visual inspection, in-situ tests ,laboratory tests and

interpretations were done to describe the ground condition. The core logs of

all the fourteen boreholes are detailed and given in the annex-V of this

report.

3.2.2.1 Layer-I: Light to Dark Brown Clay (0.00 to 3.45 m)

The top layer of the ground as indicated in all boreholes and test pits

indicate there is almost uniformly clay layer. This top layer which may be

normally excavated during the site clearing of the project has weak bearing

capacity.

3.2.2.2 Layer-II: Dark to Light Brown Silty CLAY Soil (3.45 to 6.45 m)

The clay layer has continued deep to the ground with a change on the color

and obviously on the density and the bearing capacity following

consolidation due to the over burden pressure. In this range a silty soil

behavior has encountered.

3.2.2.3 Layer-III: Brown Silty CLAY (6.45 to 9.45m)

There is still a silty clay layer in this deep depth. Checking starting from the

top most layer up to this depth, one can see that the ground is still a clay

layer with a limited variation between pure clay and silty clay. Furthermore,

such a pronounced variation in bearing capacity is not anticipated.

3.2.2.4 Layer IV: Light Brown Silty CLAY (9.45 to 13m)

In this range with a similar fashion there is no any change except the color of

the soil, it is still a silty clay soil. Regardless of the bearing capacity increase

due to overburden pressure (depth dependent), the bearing capacity is

expected to have more or less similar to the previous layers.




3.2.2.5 Layer IV: Silty Clay with Some Sand (13m to 20m)

The end of the test pits has some fluctuations ranging between 15m to 20m,

where most of them are greater than 15m. In this range, there was a change

of the soil property to have some behavior of sand. Moreover, the bearing

capacity here is relatively higher than the one above, not only due to over

pressure but also due to the change of the soil type to silty sand.

3.2.3 STANDARD PENETRATION TEST (SPT) (ASTM D1586)

Standard penetration tests were being done during the process of core

drilling. The Standard Penetration Test (SPT) was carried out using a

standard split-barrel sampler in accordance with BS1377:Part9:1990. The

test was conducted to determine the design N-values that were used to

determine the allowable bearing capacity using the empirical relationships

evolved by Terzaghi & Peck (1948) and Meyerhof (1956). The test was also

used to provide an indication of the density and consistency of the subsurface

soils . By means of the split spoon sampler and a hammer, Standard

Penetration Tests were conducted at intervals of 2.0m depth in the borehole

where possible and at points where a change in the soil profile was

realized.SPT test results are considered refusal when more than 51 blows are

required to penetrate 15cm. SPT blows were done at various depths in all

the fourteen boreholes. In each case the standard 63.5kg hammer is dropped

from 76cm to penetrate the ground at certain number of blows. The average

numbers of blows from the Standard Penetration Tests (SPT) conducted in the

borehole are as shown in the tables below. Furthermore, the results of the SPT

result are used in the computation of the bearing capacity at the borehole

locations.




Table 3.4: Measured and adjusted SPT N-Values for the project

BH No Depth (m) SPT N-Value for 300mm penetration

Adjusted N Values

Design Value

BH-01

2.15-2.45 33 31.07

30.78

4.15-4.45 50 39.58

6.15-6.45 32 23.39

8.15-8.45 50 31.93

10.15-10.45 46 27.94

BH-02

7.15-7.45 10 6.84

22.27

7.65-7.95 18 11.91

9.15-9.45 49 29.78

10.65-10.95 48 28.38

12.15-12.45 50 27.94

16.65-16.95 50 23.89

15.15-15.45 50 24.7

16.65-16.95 50 23.89

18-18.15 50 23.08

BH-03

3.15-3.45 46 36.6

30.24

5.15-5.45 50 35.8

7.00-7.30 50 34.62

9.00-9.30 50 30.39

11.00-11.30 50 29.16

13.00-13.30 50 26.73

15.00-15.15 50 25.11

17.15-17.45 50 23.49

BH-04

1.65-1.95 34 35.93

24.41

3.15-3.45 34 27.05

4.65-4.95 14 10.5

15.15-15.45 50 24.7

16.65-16.95 50 23.89

BH-05

1.65-1.95 41 43.33

29.23

3.15-3.45 34 27.05

4.65-4.95 27 20.26

6.15-6.45 50 36.55

7.65-7.95 47 31.1

9.15-9.45 50 30.39

10.65-10.80 50 29.97

12.15-12.45 50 27.94

13.65-13.95 50 26.32

15.15-15.45 50 24.7

16.65-16.95 50 23.89

BH-06 2.15-2.45 36 33.89

23.02 3.15-3.45 42

33.42




5.15-5.45 22 15.75

6.15-6.45 20 14.62

8.15-8.45 40 25.54

9.15-9.45 40 24.31

10.15-10.45 26 15.79

12.15-12.45 36 20.12

15.15-15.45 50 24.7

17.15-17.45 50 23.49

18.15-18.45 50 22.68

20.00 50 21.87

BH-07

2.15-2.45 25.33 23.85

27.21

3.45-3.75 29.33 22.27

5.15-5.45 42.66 30.54

7.15-7.45 50 34.24

9.15-9.45 50 30.39

11.15-11.45 50 29.16

12.45-12.75 50 27.54

14.15-14.45 50 25.92

15.45-15.75 50 24.7

17.15-17.45 50 23.49

BH-08

3.45-3.75 38 28.85

29.59

4.65-4.95 48 36.02

6.15-6.45 50 36.55

8.15-8.45 42 26.82

9.15-9.45 50 30.39

11.15-11.45 50 29.16

12.15-12.45 50 27.94

14.15-14.45 50 25.92

15.15-15.45 50 24.7

BH-09

2.15-2.45 24.66 23.22

25.41 3.45-3.75 28.66 21.76

5.15-5.45 44.66 31.97

15.45-15.75 50 24.7

BH-10

2.15-2.45 4 3.76

3.45-3.75 15.33 11.64

5.45-5.75 27 18.77

7.15-7.45 50 34.24

9.15-9.45 50 30.39




11.45-11.75 50 28.75

22.72 13.45-11.75 50 28.75

15.15-15.45 50 24.7

17.15-17.45 50 23.49

BH-11

1.65-1.95 21 22.19

27.85

3.15-3.45 24 19.09

4.65-4.95 34 25.51

6.15-6.45 50 36.55

7.65-7.95 50 33.08

9.15-9.45 50 30.39

10.65-10.95 50 29.56

12.15-12.45 50 27.94

13.65-13.95 50 26.32

BH-12

1.65-1.95 30 31.71

30.46

3.15-3.45 50 39.79

4.65-4.95 41 30.76

6.15-6.45 50 36.55

7.65-7.95 50 33.08

9.00-9.15 50 30.78

10.65-10.95 50 29.56

12.15-12.45 50 27.94

13.65-13.95 50 26.32

15.15-15.45 50 24.7

16.65-16.95 50 23.89

BH-13

3.45-3.75 38 28.85

22.00

5.15-5.45 25.33 18.13

6.45-6.75 24.66 17.64

8.15-8.45 50 31.93

9.45-9.75 48 28.81

11.15-11.45 30.66 17.88

12.45-12.75 20.66 11.37

14.15-14.45 42 21.77

15.45-15.75 40.66 20.09

17.15-17.45 50 23.49

BH-15

2.15-2.45 50 47.08

29.58

11.15-11.45 50 29.16

12.15-12.45 50 27.94

14.15-14.45 50 25.92

15.15-15.45 50 24.7

18.15-18.45 50 22.68

Refusal Values (SPT N> 50)




3.2.4 GROUND WATER LEVEL MEASUREMENT (ASTM D6000)

The ground water level measurement is done parallel or during the core

drilling process. In all the fourteen boreholes no ground water was encounter

within the coring depths. However, we have checked in a glance that there is

under ground water being used in the compound for different activities.

3.3 LABORATORY TESTS

Both disturbed and undisturbedsamples were collected from each of the

boreholes and the following different laboratory tests were conducted.

3.3.1 BULK UNIT WEIGHT ()

The bulk unit of all the test pits was done in the laboratory. As per the test

result, the bulk unit weight of underlain soil at the selected points ranged

from 1650 to 1970 Kg/m3.The summary of bulk unit weight of soil is

attached in the annex-IVof this report.

3.3.2 SPECIFIC GRAVITY (GS) (ASTM D854 – 14)

The specific gravity of the soil sample taken from all boreholes were

conducted in the laboratory .As per the test result, the specific gravity of

underlain soil at the selected points ranged from 2.47 to 2.72 and summary

of results are attached in the annex IV of this report.

3.3.3 WATER CONTENT DETERMINATION (%) (A5TM D 2974-87)

The percentage of water within the soil sample was determined in all the

boreholes . Summary of Test results are attached in the annex-IV of this

report.




3.3.4 SIEVE ANALYSIS (ASTM C136 / C136M – 14)

Sieve analysis test were conducted for all the samples taken from boreholes.

The test result inducate that most of the samples are fine grained soils.

Summary of Test results is attached at the annex-IV of this report.

3.3.5 CHEMICAL TEST OF SOIL

Chemical test of soil (chloride content, sulphate content, organic contents and

PH value) for every boreholes were conducted. The test result inducate that

the proposed expansion project area is free and clear of any chemical

contaminations. Summary of Test results is attached at the annex-IV of this

report.

3.3.6 ATTERBERG LIMIT TESTS (ASTM D4318 - 17E1)

The atterberg limit tests were conducted samples taken from boreholes. The

fine grained soils of silty clay and clay soil within this section had Liquid Limit

values ranging from 46.3% to 70.3% and Plasticity index values ranging

from 13.9% to 27.3%. Summary of Test results is attached at the annex-IV

of this report.

3.3.7 UNCONFINED COMPRESSION STRENGTH TEST (UCS TEST) (ASTM D2166

The UCS test is commonly used for the shear strength determination of fine

grained and cohesive soils where it’s mandatory to set up an undisturbed soil

sample. The test result indicate that the UCS of underlain soil at the selected

points ranged from 165.25 to 349.6 KN/m2and summary of results is

attached at the annex-IV of this report.

3.3.8 DIRECT SHEAR STRENGTH TEST (DSST) (ASTM D3080 / D3080M – 11)

Direct shear strength test is recommended for granular soils (none-cohesive

soils). From the sieve analysis and the atterberg tests it was also seen that

there were limited samples where they are convenient for direct shear




strength test. As per the test result, the Cohesion (KN/m2) and Angle of

Internal friction (Degrees) values of underlain soil at the selected points

ranged from 13 to 28(KN/m2) and 5.5 to 25 (Degrees) respectively .

Summary of Test results is attached at the annex-IV of this report.

3.4 BEARING CAPACITY OF SOIL

3.4.1 BEARING CAPACITY OF SOILS BASED ON LABORATORY RESULT

The bearing capacity of soil at the selected points in each borehole is

computed as per Terzaghi formulation. The table 3.5 below indicate

summary of bearing capacities soil at different depths. Since most of the BHs

has bearing capacities at different two points hence one can get a clear

image of the bearing capacity at a preferred depth. Since the laboratory

parametres are deterimned exact width can be determined by the designer.

The width figures (Df=B) used to determine the bearing capacity presented

below are allowable bearing capacity at specified depths.

Furthermore effective depth of each borehole is determined considering the

difference of original ground level (OGL) and design (finished) surface level

of the port at each borehole location. It is due to the fact that, there is high

cut and fill, some borehole locations are excavated even upto 20m and fill

more than 5m.

From the table below; majority of the boreholes indicates that the bearing

capacity is above 300Kpa at about 3m depth (shallow foundation) which is

economical. As depth increase the higher bearing capacity, however

construction cost also increases. Therefore based on the soil property and soil

type of the project maximam of 3.5m is recommended economic depth,

however based on the superstructure load the designer can decide the depth.




Table 3.5: Bearing Capacity of Selected depths

BH

Dep

th (

m)

fro

m

OG

L(s

am

ple

taken

)

To

tal exc

avate

d

Dep

th (

m)

Eff

ecti

ve

exca

vate

d d

ep

th

(fro

m f

inis

hed

level)

(m

)

Dep

th (

m)

aft

er

fin

ish

ed

lev

el

(sam

ple

ta

ke

n)

Reco

mm

en

ded

Desig

n d

ep

th (

m)

C ϕ γsat Df =B Nc Nq Ny σall

[ID]

KP

a

Deg

ree

KN

/m3

[m] [-] [-] [-] KPa

1 8-845 15 5.3

above 26 20 18.46 above 14.83 6.40 4.66

1 10-10.45 0.3-0.75

3 23 20 18.34 3.00 14.83 6.40 4.66 299.4

2 5.5-5.85 18

tested BH depth

totally removed

above

19 21 18.81 15.81 7.07 5.43

investi

gate

du

rin

g

co

nstr

ucti

on

2 10.5-10.95

above 21 21 18.71 --- 15.81 7.07 5.43

3 11-11.30 17 12.6

6.6-6.9 3 23 21 18.34 3.00 15.81 7.07 5.43 327.1

3 12-12.45 7.6-8.05 22 21 18.74 15.81 7.07 5.43

4 6-6.45

17 10.3

above 25 20 18.33 14.83 6.40 4.66

4 8.10-8.45 1.4-1.85

2.5 27 21 18.31 2.50 15.81 7.07 5.43 326.0

4 12-12.45 5.3-5.75 28 20 18.29 14.83 6.40 4.66

5 7.50-8.00

18 15.80

5.3-5.8 3.00 143 0 18.64 3.00 5.14 1.00 0.00 336.0

5 10.50-10.95

8.3-8.75

21 18 18.81 13.10 5.26 3.42

5 15.00-15.45

12.8-13.25

24 19 18.67 13.93 5.80 3.99

6

8.00-

8.30

17 22.40

5.40 3.50 20 12 18.8 3.50 9.28 2.97 1.26 156.8

6

11.70-

12.00

17.1-

17.4 19 15 19.7

10.98 3.94 2.11

6

15.70-

16.00

21.1-

21.4 20 12 18.9

9.28 2.97 1.26

7 9.00-9.45

17 15.50

7.5-7.95

3 27 19 18.71 3.00 13.93 5.80 3.99 301.4

7 10.50-10.95

9-9.45 25 19 18.36 13.93 5.80 3.99

7 13.50-13.95

12.0-12.45

22 22 18.73 16.88 7.82 6.32

8

11.35-

11.65 20

tested BH depth

totally removed

above

13 8

18.50 7.53 2.06 0.58

investi

gate

du

rin

g

co

nstr

ucti

on

8 12.45-12.80

above 15 5.5 16.50 --- 6.65 1.64 0.32




9 7-7.45 16 14

5-5.45 3.5 16 20 18.36 3.50 14.83 6.40 4.66 279.8

9 15-15.45 13-

13.45 21 19 18.47 13.93 5.80 3.99

10 6.45-6.75

19 16.00

3.45-3.75

3 149 0 17.92 3.00 5.40 1.00 0.00 367.3

10 10.50-10.95

7.5-7.95

26 22 18.10 16.88 7.82 6.32

10 17.25-17.55

14.25-14.55

24 22 17.98 16.88 7.82 6.32

11 7-7.15

15 11.85

3.85-4 3 23 21 17.98 3.00 15.81 7.07 5.43 323.8

11 12-12.30 8.85-9.15

26 20 18.24 14.83 6.40 4.66

11 13.50-13.95

10.35-10.80

24 23 18.21 18.05 8.66 7.35

12 7.50-7.95

17 17

7.50-7.95

3.5 20 19 18.55 3.50 13.93 5.80 3.99 280.8

12 10.50-10.95

10.50-10.95

27 19 18.69 13.93 5.80 3.99

12 13.50-13.80

13.50-13.80

28 21 18.70 15.81 7.07 5.43

13 12.70-13.00

20 15.2

7.9-8.2 3 21 21 18.23 3.00 15.81 7.07 5.43 312.4

13 15-15.45 10.2-10.65

10 23 21 18.47 15.81 7.07 5.43

15

1.50-

1.95

20 16.20

above 83 0 18.30 5.41 1.00 0.00

15

6.00-

6.30 2.2-2.5 2.50 28 23

18.80 2.50 18.05 8.66 7.35 400.8

15

12.00-

12.45

8.2-

8.65 25 25

18.80 20.72 10.66 9.94




3.4.2 BEARING CAPACITY OF SOILS BASED ON FIELD SPT N- VALUES

Foundation recommendation refers to fixing the bearing layer and depth

from the OGL, allowable pressure on the bearing layer and type of

foundation to be adopted safely and economically. The main factors to be

considered while selecting a foundation are the load to be transmitted to the

foundation and the subsurface condition of the soil.

SPT tests are the dominant methods to determine the allowable bearing

capacities of the foundations since it is easy to compute the bearing capacity

of the ground at different depths. However, in this investigation sample was

collect and put it in to Direct Shear Strength Test (DSST) at only selected

depth on each borehole hence it is difficult to compute the bearing capacity

of the ground at different depths using results of laboratory tests.

SPT values will therefore be used to compute the bearing capacity of the soil

layers below the foundation as an alternative to the values computed using

the laboratory tests. Allowable bearing capacity for the selected layer is

based on correlation of the relative compaction of the in-situ ground as

indicated from SPT and after all the necessary adjustments are made to

determine the actual SPT values

In order to determine the bearing capacity soil ,it is necessary to know the

load from the super structure. The maximum pressures the soils are capable

of resisting were estimated from the field SPT N-values using empirical

relations. For purposes of computing the soil’s bearing Capacity, the

maximum allowable settlement in cohesive soils is 25mm;

After adjusting the N-Values, design N-values are chosen from consecutive

depths where the test is performed. The design N-Values are taken as the

average of adjusted N-values which are found in between ½ B above and

2B below the proposed footing depths where B is the width of the




foundation. The data record from all boreholes was used to compute the

allowable bearing capacity of the geotechnical layer.

The bearing capacity for an footing can be calculated from the SPT N-values

using Meyerhof’s equation as follows (Bowles, 1997):

qall=N/F2*(1+F3/B)2*1/Kd………………………B>F4

Where

qall= Allowable bearing capacity for settlement limited to 25 mm.

The following allowable bearing pressures are computed for isolated

footings placed at a depth of 2.5m below the natural ground level. However,

the SPT tests are done at various depth deeper than 2.5m.However; the

ground condition in most boreholes starting from 0.00m to the end is quite

similar and the SPT reading at 6.45m to 8m with obvious understanding of

the effect of the depth can be considered for that of 2.5m. Foundation widths

are varied from 2.0m to 4.5m. A maximum settlement limit of 25mm is taken

in to account for the allowable bearing capacity computation.

Table 3.6: Allowable bearing pressure (kPa) based on SPT at depth of 2.5m

Footing Width (m) 2 2.5 3 3.5 4 4.5

Design N-Value (Minimum is considered here)

22 22 22 22 22 22

Kd-calculated 1.41 1.33 1.27 1.23 1.2 1.18

Kd-designed 1.33 1.33 1.27 1.23 1.2 1.18

Allowable bearing pressure

343.91 345.82 349.34 351.39 353.1 353.54

From the above analysis, it is revealed that the allowable bearing pressure

computed using bearing capacity equations from SPT test results at a depth

of 2.5m and width ranging from 2 to 4.5mvaries from 343.91kPa to

353.54kPa. The bearing capacity equation is calculated considering 25mm

settlement as the maximum threshold.




3.4.3 SETTLEMENT ANALYSIS

Settlement is another criterion for evaluating the performance of structure

because excessive settlements will result in poor performance of the structure.

Various codes set the limiting settlement for the type of structure and

foundation. The proposed foundation should hence meet this limit. Though

different types of settlement are there, the major ones are immediate and

consolidation settlements.

These two settlements depend on a number of parameters as well as type of

soils.

As discussed in different portions of this project, the sub surface condition at

the depth of each of the test pits is week ground where it is dominated with

clay soils. In this project, the consolidation settlements are anticipated to

happen, if the conditions of the soil is not given a due attention during design

and construction.

3.5 RETAINING STRUCTURES

In sections where there are high cut and high fill, which are more expected

as there is a varies topography on the project area, retaining structures of

different types which mostly are dependent on the height and behavior of

the ground to be retained are anticipated to be used.

The following retaining walls are among the common ones that are

recommended for this specific project considering the behavior of the ground

form both the laboratory and field tests summarized in this report.

Masonry Retaining wall (if the height to be retained is preferable less

than 4.5m)

Cantilever retaining walls (if the height to be retained is more than 4.5m)




CHAPTER–4

LOCATION AND TESTING OF CONSTRUCTION MATERIALS

4.1 GENERAL

Basic objective of construction material investigations is to identify the

potential sources of construction materials along the project vicinity, to yield

adequate quantity of materials which are suitable for various pavement

layers viz. embankment, sub grade, sub base, base, concerte ,etc.

Suitable material sources have been identified along the project vicinity by

local enquiry. Besides ,consultant has carried out tests on selected material

sources to find their suitability for use. Sufficient material sources have been

identified to verify availability of materials within economical leads.

The information on the materials sources were summarized with the following

objectives:

Identification of source locations indicating places and the status of

sources whether in operation or new sources.

Identification of requirements for pavements, embankment works, cross

drainage and other works.

Testing and evaluation of materials for use in works

Material specification and characteristics.

The Consultants has identified rock quarries for various pavement layers such

for crushed subbase,stablized base course ,concrete pavement works and

borrow sources for earth work , embankment or capping layer. Large quantity

of borrow source is available near to modjo green logistics Hub. The samples




were tested in the laboratory to evaluate their suitability for construction.

Location of various quarries and borrow sources are given in table below.

Potential sources of construction materials were investigated through the

following activities:

A Desktop study: The information that was studied includes

geological maps, geological reports and topographical maps.

Discussion with Contractor on the going project of the port:

communication with the contractor represntative of the on going

project port was enquired about the existence of potential

sources of construction material.

Enquired local people: Local people on the vicinity of the

project were enquired about the existence of potential sources

of construction material.

Field investigation: All potential sources were investigated,

inspected and evaluated.

Laboratory tests: labortory tests were conducted on the

identified construction material source to assess the suitablity of

material quality and to compare with the specifications

requirement.

In general prior to locating construction material sources the following factors

were considered:

Performance of the material to be used for construction;

Accessibility;

Quantity and Quality;

Type and thickness of overburden materials;




Availability of ample space for erecting crusher and stockpiling

;and

Environmental and social aspects

Taking into account these factors the following potential sources of

construction material were identified.

4.2 GRAVEL BORROW SOURCE INVESTIGATION

The investigation of borrow materials which can be used for the construction

of earth work , embankment or capping layer is conducted in the project

vicincity. Normally natural granular materials have shown inconsistency

proprties even in the single source which as a result of frequent change in

weathering and extreme variability of geological and tectonic processes that

are responsible for their present state of occurrences.

The natural gravel sources investigations was carried out from January to

February 2019. Overburden thickness, suitability of extraction, sufficiency

and the impacts to local settlement were considered during selection of

potential borrow source. As per the investigation,only one(1) large quantity

of borrow source was identified around Modjo green logistics hub ,which is

located 1.5km far from the main gate at melmel village and the source is

sufficent for the construction works . Pit excavated and samples were

recovered from sources for laboratory testing. The locations and description

of the borrow source is indicated in the table 4.1 below.

Table 4.1: Description of borrow source

SN GPS Location Offset/

Distance

Estimated

quantity

(m3)

Type of Material and

status

BP1 0514801,

0946849

Melmele

kebele

1.5 from

the main

gate

≈1,300,000 Slightily weatherd

gravel material

Existing source




The recovered sample from source was delivered to the laboratory for

testing. Tests are being carried out on these samples to determine the

physical and mechanical properties of the soil which can be used to classify it

as suitable for earth work ,embankment and cappinglayer. The sample is

tested in accordance with several appropriate standards shown in table 4.2

below.

Table 4.2: The tests to be carried out on natural gravel source samples

Test No. Name of Test Standard Test

Method

Sample Status

1 Liquid Limit AASHTO T-89 Disturbed

2 Plastic Limit AASHTO T-90 Disturbed

3 Linear shrinkage BS 1377: Part 2:

1990

Disturbed

4 Sieve analysis AASHTO T-27 Disturbed

5 Maximum Dry Density

(MDD)

AASHTO T-180 Disturbed

6 California Bearing Ratio (CBR) and CBR-swell

AASHTO T-193 Disturbed

In order to assess the suitability of the materials tested as selected fill and as

embankment fill, the test results obtained were compared with the

requirements of specifications as given in table 4.3 below.

Table 4.3: Summary of test result of Natural gravel sources

Station (location) CBR value (%)

LL (%)

PI (%) LS (%) CBR-Swell (%)

Melmele(1.5km far from the main gate)

25 NP NP NP 0.1

Material Requirement for

capping layer or fill

≥15 <45 <12 6.0 <1.5




As per test results ,the identified borrow source is granular material and

suitable for selected capping layer and embankment fill. Besides ,it may

require proper verification on borrow site during construction time to check it

consistency and satisfy project specification.

Figure4.1: Natural gravel source at Melmele kebele




4.3 ROCK QUARRY SOURCES

Investigation of quarry sources that will use for crushed subbase,stablized

base course and concrete pavement works have been undertaken in the

Modjo logistics green hub project.

Potential quarry sources for aggregate to use in construction of crushed

subbase,stablized base course , concrete pavement works and other

structures are available only at two places, in the nearby vicinities of the

project area within reasonable haulages and samples were collected for

laboratory testing. Overburden thickness, suitability of extraction, sufficiency

and the impacts to local settlement were considered during selection of the

quarry.

The recovered samples were delivered to the laboratory for testing. Tests

are being carried out on these samples to determine the physical and

mechanical properties of the rock which can be used to classify it as suitable

for intended pourpose. The samples were being tested in accordance with

several appropriate standards shown in table 4.4 below.

Table 4.4 Tests to be carried out on the rock sample

Test No. Name of the test Standard test method

1 Aggregate Crushing Value (ACV) test BS 812, Part 110: 1990

2 10% Fines Value (TFV) test BS 812, Part 111: 1990

3 Aggregate Impact Value BS 812, Part 110: 1990

4 Sodium sulphate soundness AASHTO T104

5 Water absorption ASTM D6473

6 Los Angeles Abrasion Value ASTM C131-89

Summary description of potential rock quarry source is presented table

below.




Table 4.5: Summary of Rock Quarry source

SN Station GPS Estimated quantity(m3)

Type of material

Remarks

Q1 Within the project compound

516383, 949052

160,000.0 granite/ Ignimbrite rock

Existing quarry soucre and acceptable for crushed aggregate

Q2 11.8 Km towards Debrezeit

0643652, 102494

1,000,000.0

Basaltic rock

Existing quarry soucre and acceptable for crushed aggregate

Figure4.2: Rock quarry source within the compound (Q1)




Figure 4.3: Rock quarry Source 11.8Km towards Debrezeit (Q2)

Aggregate Crushing Value (ACV), Aggregate Impact Value , 10% Fines

Value (TFV) test ,Sodium sulphate soundness, Water absorption and Los

Angeles Abrasion Value tests were conducted on the samples to assess their

suitability. The test results on rock sample are compiled in the table 4.6

below. The rock samples test result were compared with corresponding

requirements for crushed aggregates in table 4.6 below.




Table 4.6: Test result and requirements for rock aggregate

Parameters Specification

Test result

Quarry (Q1) Quarry (Q2)

Aggregate Crushing Value Max 29% 26 13.0

Aggregate Impact Value Max 25% 19 12.82

Los Angeles Abrasion (LAA) Max 30% 21 18.00

Sodium Sulphate Soundness Min 10% 1.29 2.38

Water absorption 5.99 1.10

Bulk specifc gravity 2.16 2.38

Appernt specifc gravity 2.48 2.44

Four days soakedCBR CBR>80% 83% 95%

As per the test results, the both rock quarry sources are comply the

requirment for crushed subbase, stablized base course and for concrete

pavement works in accordance with specification however, high water

absorption result at quarry source one(Q1) needs to be recheck during

construction stage.

4.4 NATURAL SAND SOURCES

Investigation of natural sand sources for concrete pavement works has been

undertaken in the Modjo logistics green hub vicincity. Potential sand sources

to use in construction of concrete pavement works and other structures are

available only at two places, the first source is located 150km far from

modjo town towards Hawassa (around langano) area called seva and the

second source is located 15km far from the project area on the way to

zeway. The samples from both sources were collected for laboratory testing

to assess its suitability for use as fine aggregate for concrete.

The quality test such as Clay lumps & friable particles, gradation, organic

impurity, specific gravity, water absorption, Soundness, mortar strength and

sand equivalent were conducted on the collected samples .The quality of the




sand sample was assessed with respect to AASHTO M6 specifications for fine

aggregates for use in concrete.

The natural sand from Sand (S1) offset 150km fromModjo, has organic colour

No 02, the soundness loss of 9%, the clay content is 1.26%, sand equivalent

92% and water absorption 2.15%. The gradation is with the allowable limit

enveolpe. From the test results, the sand has fulfilled the requirement and thus

it is suitable for construction of concrete works. However tarnsportation

(haulage) cost makes it uneconomical.

The natural sand from Sand (S2) offset 15km from Modjo has organic colour

No 02, the soundness loss of 12%, the clay content is 13.9%, sand equivalent

74% and water absorption 4.4% and the gradation is finer than the

allowable limit . From the test results, the sand has not fulfill most of the

requirement thus it is not suitable for construction concrete works. Therefore it

require thoroughly washed to minimized clay content but this may not be

economical due to high clay content.

Generally for concrete pavement works and other structures works, significant

amount of sand will be required however the identified natural sand source

may be deficient to satisfy the actual project demand for all concrete

pavement works and other structures works. In view of this prevailing

conditions, it is recommended that use of crusher run sand (material passing

the 4.75mm sieve from the crusher site) shall be the most likely solution to

avoid facing such problems for all concrete works. Since the parent rocks

satisfy all quality requirements, the crusher run sand as its by-product will

surely satisfy the required quality requirements.




0

20

40

60

80

100

120

0.1 1 10

% o

f p

assi

ng

Sieve Size mm

sieve analysis of natural sand

Min

Max

S1

S2

Figure 4.4: sieve analysis of natural sand sources

Table 4.7: Test result and requirements for natural sand source

Parameters Specification

Test result

Sand (S1) (offset

150km fromModjo)

Sand (S2) (offset

15km fromModjo)

Organic impurity Max No 3 2.0 2.0

Sodium sulphate soundness (%) Max 10% 9.0 12.0

Clay lumps & friable particles Max 3% 1.26 13.9

Water Absorption Max 2% 2.15 4.4

Sand Equivalent Min 75 92.0 74.0

Bulk specifc gravity 1.89 1.78

Appernt specifc gravity 1.97 1.80




4.5 WATER SOURCES FOR CONSTRUCTION

Water is required for compaction, concrete and mortar works, therefore, trial

was made to locate all perennial and seasonal rivers that drain to the project

vicincity. As per the investigation it has observed a scarcity of natural water

sources in the project area thus to overcome water shortage especially for

the compaction works and it is recommended to produced water from under

ground within the compound .Besides , we have checked in a glance that

there is under ground water being used in the compound for different

activities.

Althogh the ground water is drinkable and need of testing; however for the

purpose of the report, sample was collected from the ground water, and

laboratory quality test was conducted. Based on the test result this groud

water is clear and qualified for the intended purpose. The testresult is

attached in the annex.




CHAPTER–5

CONCLUSIONS AND RECOMMENDATIONS

5.1 CONCLUSION

Test pit excavations and sampling, dynamic cone penetration tests, borehole

drilling and sampling, assessment of construction materials and sampling were

conducting during field investigation stage. Samples from test pit, borehole

and construction materials were also collected and delivered to laboratory

for further laboratory tests. Laboratory test result were analysised

conclusions and recommendations were aslo drawn based on field and

laboratory test result analysis.

Due to the coverage of accumulated of waste/spoiled material on the

expansion project (waste material from existing construction) and due to high

cut section mainly on north side of the project; test pit excavation and DCP

test wasn’t carried out during design stage.

Based on the test pit (sub grade laboratory test) and DCP test results, above

85% of the project area is unsuitable for pavement foundation.

The project area is located in active seismic zone are (Zone-4) and it is also

in the vicinity of the Rift valley. This area hence needs attention in case there

is a plan for the construction of high raised building and other important

cases like machine foundations where the draw serious attention during the

foundation design.

The bearing capacity results attached in this report are just at different

depths where our foundation may not be placed there. Therefore, the

bearing capacity at different depths (where the designer needs) can be

computed using the SPT results attached in the Logs.




The sub surface condition at the depth of each of the test pits is week ground

where it is dominated with clay soils. In this project, the consolidation

settlements are anticipated to happen, if the conditions of the soil is not given

a due attention during design and construction.

The subsurface formation of the test pit log and the 14 boreholes

investigation dominately indicates that the area is covered with thick

formation of clay to silty clay soil.

Enough amount of borrow and quarry sources were identified at the vicnity

of the project area, which can satisfy the needed amount and quality of the

project area.

Two sand sources were identified; however one of them is qualified but

150km far which is uneconomical to use it due to haulage distance; the other

source is 15km far but very fine and unqualified for the intended purpose.

5.2 RECOMMENDATIONS

From the above conclusion, one can recommend the following main points

regarding of the soil and material investigation.

Due to the coverage of accumulated of waste/spoiled material on the

expansion project (waste material from existing construction) and due to

high cut section mainly on north side of the project; test pit excavation

and DCP test wasn’t carried out during design stage, thus it is

recommended to conduct the test during construction after clearing the

waste material and excavation of the cut section.

For unsuitable soil locations, the best recommended option of mitigation

of problems is excavation and replacement options. The depth and

extent of this replacement method is as indicated in chapter 2. The

removed material should be replaced by a suitable, non-expansive and




impermeable material, the material requiremant for eath work and

capping layer is indicated in chapter four.

From the discusions and conclusion given above, it can be seen that the

ground almost uniformly CLAY and Silty CLAY. For the actual project site, the

following general recommendations of geotechnical based are important.

In case shallow foundations are selected as foundation option,

provided that there are only light structures, the construction need to

be facilitated in the dry season to avoid the effect of the volume

change of the CLAY soils.

Shallow foundations (Isolated and Mat Foundations) for light structures

and Pile foundation for heavy structures (if any) are recommended on

this site

Retaining structures (where their type depends on the actual height of

the section to be retained) are recommended in sections of high fill and

high cut.

Considering the significance amount of needed for the project and the

economic haulage distance of natural sand, it is recommended that use of

crusher run sand (material passing the 4.75mm sieve from the crusher site)

shall be the most likely solution to avoid facing such problems for all concrete

and masonry works

Documents

Annex 1 Final Soil Material Investigation Report