Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show. Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.

1. 1
Geotechnical Engineering–II [CE-321]
BSc Civil Engineering – 5th Semester
by
Dr. Muhammad Irfan
Assistant Professor
Civil Engg. Dept. – UET Lahore
Email: mirfan1@msn.com
Lecture Handouts: https://groups.google.com/d/forum/geotech-ii_2015session
Lecture # 20
17-Nov-2017

2. 2
Case I
Groundwater table is located
at a distance D above the
bottom of the foundation.
Case-I
 BNNDcNq qfcult 5.0
1. Modify γDf term as
γ(Df – D) + γsub.D
2. Modify 0.5γBNγ term as
0.5γsubBNγ
Where,
γsub = γsat - γw
EFFECT OF GROUNDWATER TABLE
ON BEARING CAPACITY

3. 3
Case II
Groundwater table is located
at the foundation base.
 BNNDcNq qfcult 5.0
1. No change to γDf term.
2. Modify 0.5γBNγ term as
0.5γsubBNγ
Where,
γsub = γsat - γw
Case-II
EFFECT OF GROUNDWATER TABLE
ON BEARING CAPACITY

4. 4
Case III
Groundwater table is located
at a depth D below the
foundation base.
 BNNDcNq qfcult 5.0
1. No change to γDf term.
2. Use γav in the third term;
γav = γ (for D > B)
γav = 1/B [γD + γsub (B – D)] (for D ≤ B)
γsub = γsat - γw
Case-III
EFFECT OF GROUNDWATER TABLE
ON BEARING CAPACITY

5. 5
Practice Problem #5
Compute the factor of safety
against a bearing capacity failure
for the square spread footing
shown in figure with the
groundwater table at Position A.
Some time after construction, the
water table rises to Position B.
Compute the new factor of safety
against bearing capacity failure

6. 8
Terzaghi (1943) developed the theory for continuous/strip
foundations (simplest, 2D problem).
 BNNDNcq qfcult '5.0'' 
Contribution of:
Shear
strength
Surcharge
Soil self-
weight
 sBNNDsNcq qfccult '5.0'' 
General form of Terzaghi’s Bearing Capacity Theory
sc and sγ → shape factors
TERZAGHI’S BEARING CAPACITY THEORY

7. 9
 BNNDNcq qfcult '5.0'' 
TERZAGHI’S BEARING CAPACITY THEORY

8. 10
Practice Problem #6

9. 12
GENERAL BEARING CAPACITY
EQUATION

10. 13
GENERAL BEARING CAPACITY EQUATION

11. 14
Practice Problem #7

12. 16
Practice Problem #8

13. 18
CONCLUDED
REFERENCE MATERIAL
Foundation Analysis and Design (5th Edition)
Joseph E. Bowles
Chapter #4
Principles of Geotechnical Engineering (7th Edition)
Braja M. Das
Chapter #16