A rectangular footing of size 10 x 20 ft is founded at a depth of 6 ft below the ground level in a cohesive soil (0 = 0) which fails by general shear. Given: ysal =114 lb/ft3, c = 945 lb/ft2. The water table is close to the ground surface.

Determine q , q and qna by

(a) Terzaghi’s method, and

(b) Skempton’s method. Use Fv = 3.

**Solution**

**(a) Terzaghi’s method**

**(b) Skempton’s method**

From Eqs. (12.22a) and (12.22d) we may write

Note: Terzaghi’s and Skempton’s values are in close agreement for cohesive soils

Rectangular footing considered to support the column loading as shown below

a. Proportion footing

b. Design the rectangular footing

qall=150kpa

Use c_25

S_300

Dl=500

Ll=200