Geotecnical & Soil Interpretation

8/8/2019 Geotecnical & Soil Interpretation

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TABLE ( 1 ): MINIMUM REQUIRED NUMBER AND DEPTH OF BOREHOLESMEASURED FROM FOUNDATION LEVEL

No. of Storeys

Area of Story

(m2)

Total No. of Boreholes

MinimumDepth of

Two-Thirdsof Boreholes

(m)

MinimumDepth of

One-Thirdof Boreholes

(m)

Minimum Required Lab. Tests

Granular

Soil

Cohesive

Soil

Rock

3

< 200 2 3 6

Gradation,Field

Density if

possible,Direct

Shear Testif possible,

or TriaxialTest if

possible,Standard

Penetration

Gradation,Moisturecontent,Atterberg

Limits, UCSTest,

SPT Test

UCSTest,pointLoad,RQD

200-600 3

5 8601-800 4

801-1000 5

1001-1200 6

> 1200 Special Study

4

< 200 2

6 9

AboveMentionedTests Plus

TheTriaxialTest if

ibl

200-600 3

601-800 4

801-1000 5

1001-1200 6


5

< 200 2

7 11

200-600 3

601-800 4801-1000 5

1001-1200 6


6

< 200 2

8 12

200-600 3

601-800 4

801-1000 5

1001-1200 6

1200



Penetration possible1200 S i l St d

ALLOWABLE BEARING PRESSURE IN SAND BASED ON SETTLEMENT OF 1 in (25.4 mm),

TERZAGHI & PECK, 1948

350

400

450

500

550

600

650

700

750

800

E B E A R I N G P R E S S U R E , q n e t ( a l l ) ( K P a )

N=40

N=45

N=50

N=55

N=60

qnet (all)=35(N'-3)((B+0.3)/(2B))2

;for B>or=1.22m(4 ft)

If 0<N<10 Loose;

10<N<30 Medium;

30<N<50 Dense;

50<N Very Dense



ALLOWABLE BEARING PRESSURE IN SAND BASED ON SETTLEMENT(for 1 in or 25.4 mm)

CONSIDERATION(MEYEROHF, 1956)

300

350

400

450

500

550

600

650

700

750

800

WA

B L E B E A R I N G P R E S S U R E , q n e t ( a l l ) ( K P a )

N=60

N=55

N=45

N=40

N=35

N=50

qnet (all)=12N';for B<or=1.22m(4 ft)

qnet (all)=8N'((3.28B+1)/(3.28B))

2

for B>1.22m(4 ft)

If 0<N<10 Loose;

10<N<30 Medium;

30<N<50 Dense;

50<N Very Dense



CLASSIFICATION OF SOILS AND SOIL-AGGREGATE MIXTURES BY AASHTO CLASSIFICATION S YSTEM

General Classification

Granular Materials

35% or Less Passing the No. 200 (0.075 mm)

Silt-Clay Materials

More than 35% Passing the No. 200

A-1 A-2 A-7

Group Classification A-1-a A-1-b A-3 A-2-4 A-2-5 A-2-6 A-2-7 A-4 A-5 A-6

A-7-5

A-7-6

Sieve Analysis: % Passing2.00 mm (No.10) 50 max - - - - - - - - - -

0.425 mm (No.40) 30 max 50 max 51 min - - - - - - - -

0.075 mm (No.200) 15 max 25 max 10 max 35 max 35 max 35 max 35 max 36 min 36 min 36 min 36 min

Characteristics of Fraction Passing 0.425 mm (No.40)

Liquid Limit - - 40 max 41 min 40 max 41 min 40 max 41 min 40 max 41 min

Plasticity Index 6 max NP 10 max 10 max 11 min 11 min 10 max 10 max 11 min 11 min 1

Usual Types of Significant

Constituent Materials

Stone Fragments,

Gravel & Sand

Fine

Sand

Silty or Clayey Gravel & Sand Silty Soils Clayey Soils

General Ratings as

Subgrade

Excellent to Good Fair to Poor

(1) Plasticity Index of A-7-5 subgroup is equal to or less than (LL – 30). Plasticity Index of A-7-6 subgroup is greater than (LL – 30)

Group Index=(F-35)[0.2+0.005(LL-40)]+0.01(F-15)(PI-10) ; Where

F=Percentage of soil passing No.200 sieve, LL= Liquid limit, PI= Plasticity index

If the computed GI is 0 or –ve then it should be reported as (0)

Classification of a soil is reported as; A-2-6 (5)

Created by Dr. M. AL-SMADI 41162231.doc: 10/1/2010

Soil

Group

Group

Index

4

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Geotecnical & Soil Interpretation