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Session 5 – 6 SOIL INVESTIGATION

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SOIL INVESTIGATION AND LABORATORY TESTS

• SOIL INVESTIGATION• LABORATORY TESTINGS• EMPIRICAL CORRELATIONS

– CPT AND N-SPT VALUE– BETWEEN SOIL PARAMETER

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SOIL INVESTIGATION

• PURPOSE– To describe the soil condition and its stratification.– To get the soil sample for laboratory testing

• undisturbed sample• disturbed sample

– To find out the ground water level– To get the soil properties directly– In-situ Test

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SOIL INVESTIGATION

• STAGES– Site Inspection– Initial Investigation

• Cone Penetration Test (Sondir)– Advance Investigation (detail)

• Boring and sampling • Standard Penetration Test • Pressuremeter• Dilatometer

– Additional Investigation

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SOIL INVESTIGATION

• DEPTH OF SOIL INVESTIGATION– Shallow Foundation : 3 x Foundation width (min. 9m)– Raft Foundation : 2 x Foundation width– Pile Foundation : 2 x Pile width (measured from pile tip)– Pile + Raft Foundation : 2 x building width– Retaining Earth Structure : 0.7 x cutting width or 1 x cutting height (take

the biggest)– Soil Embankment : 2 x embankment width

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SOIL INVESTIGATION

• NO. OF SOIL INVESTIGATION– Initial Investigation :

• Normal Soil : every 100 to 200 m• Soft Soil : every 50 to 100 m

– Detail Investigation :• Square structure : every 15 to 25 m• Strip structure : every 25 to 50 m

– At the important side of the structure, the number of soil investigation can be increased

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BORING INVESTIGATION

• AUGER BORING• WASH BORING• CORE DRILLING• TEST PIT

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BORING INVESTIGATION

• AUGER BORING (PENGEBORAN MANUAL)– Carried out by pushing and rotating the auger into soil– Limited application, only suitable for shallow foundation– Not suitable for boring under ground water table– Simple, easy to operate and minimum disturbance to soil

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BORING INVESTIGATION

• WASH BORING (PENGEBORAN BILAS )– Use rotary bore machine– Soil dig and washed by water circulation– Can not used for soil identification– Less suitable for rock boring– Suitable for all type of soil– Very suitable for soft soil– Disturbance to soil structure is minimum

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BORING INVESTIGATION

• CORE DRILLING (PENGEBORAN INTI)– Use rotary bore machine– Single tube without water circulation– Double or triple tube with water circulation– Can use for rock– Can identify soil directly– Not suitable for boring of soft soil– Can make a disturbance soil structure

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BORING INVESTIGATION

• TEST PIT– Carried by excavated soil manually– For shallow depth– Difficult to apply to soil with high water level– Very simple and relative cheap– Identification can be done directly by visual.– Large number of soil sample

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SAMPLING METHOD

• UNDISTURBED SOIL SAMPLING (CONTOH TANAH TAK TERGANGGU)– Sampling Technique

• Sensitive and soft to very soft clay or silt thin wall tube + piston• Soft to medium stiff clay or silt shelby thin wall tube sampler• Hard to very hard clay or silt thick wall tube sampler or Denison

or Pitcher samplers

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THIN WALL and PISTON SAMPLER

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THICK WALL and DENISON SAMPLER

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SOIL SAMPLER TUBE (ASTM D1587)

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• UNDISTURBED SOIL SAMPLE (CONTOH TANAH TAK TERGANGGU )– Storage Technique/Sample treatment

• The tube shall be covered by paraffin candle• Storage at cool place and at vertical position• Shall be labeled to facilitate soil identification• The tube shall be folded by foam during transportation• The laboratory tests shall be carried out as soon as possible

SAMPLING METHOD

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SAMPLING METHOD

• DISTURBED SOIL SAMPLE (CONTOH TANAH TERGANGGU )– Sampling Technique and Sample Treatment

• Can get from core drilling or SPT tube • Shall be folded by plastic and storage at cool place• Shall be labeled to facilitate soil identification

– Usually use for fill material

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• BASIC AND SIMPLE INSITU TEST– Standard Penetration Test (SPT)– Cone Penetration Test (CPT)

• INSITU TEST for DIRECT MECHANICAL PROPERTIES OF SOIL– Field vane shear test Soil Strength– Pressuremeter Test/Lateral Load Test (LLT) Soil Deformation– Flat Dilatometer Test Soil Deformation– Plate Bearing Test Strength and Deformation of Soil

INSITU TEST (UJI LAPANGAN)

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• PRINCIPLE OF WORKCarried out by punching the standard tube to bore hole using free fall 63.5 kg hammer from 760mm height. The number of blows required for spoon penetration of three 150mm. The number of blow counted at the last of 300mm penetration.

• RULES– Dimension of SPT tube according to ASTM D1586– The hammer type is conventional or automatic

STANDARD PENETRATION TEST (SPT)

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• ADVANTAGES– Could be used to identify soil types visually– Could be used to get qualitative soil properties by empirical

correlation• LIMITATION

– The soil strength profile can not be measured continuously– The high accuracy is needed during investigation in case of weight

and falling height of hammer

STANDARD PENETRATION TEST (SPT)

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SPT HAMMER

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DIMENSION OF SPT TUBE

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EXAMPLE OF BORING LOG AND SPT

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SPT EXECUTION

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• TYPE OF PENETROMETER AND PRINCIPLE OF WORK– Mechanical friction-cone penetrometer

by pushing a cone with projection area 10 cm2 and 60o angle and standard velocity 20 mm per-second.

2 measurement parameters each 20 cm of depth:• Cone Resistance (qc)• Local Friction (fs)

– Electric friction-cone penetrometermeasure the cone pressure and continuously friction with better accuracy level

CONE PENETRATION TEST (CPT)

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CONE PENETRATION TEST (CPT)

• ADVANTAGES– Continuous Soil strength profile– Give fast description of soil– Simple

• LIMITATIONS– Bad accuracy for soil with some stones– Mechanical friction-cone penetrometer is less sensitive when

applied in very soft clay

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CPT CONE SIZE (ASTM D 3441)

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ELECTRIC FRICTION-CONE PENETROMETER TIP

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EXAMPLE OF CPT GRAPH

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FIELD VANE SHEAR TEST (FVT)

• Measure undrained shear strength of soil• Suitable for very soft clay to medium stiff clay• Principle of equipment operation : vane pushed and rotated• The vane shear equation :

• Correlation between vane shear and shear strength of soil

H3D1x

2HDx

10

Ts2

6

fv

fvu s.s

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FIELD VANE SHEAR TEST (FVT)

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PRESSUREMETER TEST (PMT)

• Measure the strength and deformation of soil• Recommended use for the soil which need elastic settlement prediction• Equipment mechanism : expanding the rubber cylinder of water by using

air pressure

Soil Types Limit Pressure (kN/m2) EM/pl

Soft clay 50 – 300 10

Firm clay 300 – 800 10

Stiff clay 600 – 2,500 15

Loose silty sand 100 – 500 5

Silt 200 – 1,500 8

Sand and gravel 1,200 – 5,000 7

Till (Tanah liat berbatu) 1,000 – 5,000 8

Old fill 400 – 1,000 12

Recent fill 50 – 300 12

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PRESSUREMETER TEST (PMT)

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DILATOMETER TEST (DMT)

• Have similar purpose and equipment mechanism with Pressuremeter

• The difference is in the pressure direction :– DMT one direction– PMT radial

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DILATOMETER TEST (DMT)

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PLATE LOAD TEST

• Measure strength and deformation of soil• Use to determine bearing capacity of soil and its settlement especially for

shallow foundation• Work mechanism : push the circle/square plate at the certain depth with

load of 2 – 3x design load until rupture• Loading influence : 1.5 – 2x plate width• Relationship to undrained shear strength:

Su = (qu - t.H)/Nc

qu = rupture load t = unit weight of soil H = thickness of soil on the sample surface Nc = bearing capacity factor

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• Purpose:– Ground water elevation– Seepage behaviour

• Method:– Ground water elevation

• Observation at bore hole• Observation at observation

well (standpipe)• Measure using piezometer

– Seepage behaviour• Seepage test at bore hole• Pump test at bore hole• Large scale of pump test

GROUND WATER INVESTIGATION

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PIEZOMETER

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PUMPING TEST

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LABORATORY TESTS

• Soil Index (, , e, GS etc.)– Measurement of soil volume and mass– Sieve analysis test– Atterberg test

• Shear Strength (c, )– Triaxial Test (UU, CU, CD)– Direct Shear– Unconfined Compression Test

• Compresibility (Cc, Cv)Consolidation test

• Permeability (k)– Constant Head– Falling Head

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EMPIRICAL CORRELATION

• N-SPT value

Sandy Soil Clayey or Silty SoilN-SPT Value Relative Density N-SPT Value Consistency

0 – 4 Very loose 0 – 2 Very soft

4 – 10 Loose 2 – 4 Soft

10 – 30 Medium 4 – 8 Medium stiff

30 – 50 Dense 8 – 15 Stiff

> 50 Very dense 15 – 30 Very stiff

> 30 Hard

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EMPIRICAL CORRELATION• CPT value

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• Between soil properties– Cc = 0.009 (LL – 10)– C = qu/2– C = (19 – 23) CBR (C in kN/m2)

EMPIRICAL CORRELATION