Skempton Theory

Q. The ultimate bearing capacity of a square footing on surface of a saturated clay having unconfined compression strength of 50 $kN/m^2$ (using skempton's equation) is

1. $250kN/m^2$
2. $180kN/m^2$
3. $150kN/m^2$
4. $125kN/m^2$

Q. A strip footing having 1.5m width founded at a depth of 3 m below ground level in a clay soil having $c=20kN/m^2,\varphi =0^{\circ }andunitweight\gamma =20kN/m^3$ What is the net ultimate bearing capcity using Skempton's analysis ?

1. $30kN/m^2$
2. $60kN/m^2$
3. $100kN/m^2$
4. $140kN/m^2$

Q. A rectangular footing $1m\times 2m$ is placed at a depth of 2 m in a saturated clay having an unconfined compressive strength of $100kN/m^2$. According to Skempton, the net ultimate bearing capacity is

1. $420kN/m^2$
2. $412.5kN/m^2$
3. $385kN/m^2$
4. $350kN/m^2$

Q. A rectangular footing $L\times B$ is to be placed at a depth D below ground level such that $\frac{D}{B}<2.5$ . The factor $N_c$ to be used in deciding of the allowable bearing capacity for the footing as given by Skempton is calculated using the equation
(where, $N_{CR}=N_C$ for rectangular footing,
$N_{CS}=N_C$ at surface )

1. $N_{CR}=1.4N_{CS}$
2. $N_{CR}=(1+0.2\frac{D}{B})N_{Cs}$
3. $N_{CR}=(1+0.2\frac{B}{L})N_{Cs}$
4. $N_{CR}=(1+0.2\frac{B}{L})(1+0.2\frac{D}{B})N_{Cs}$

Q. A bridge of $40\times 10m$ is to be founded on the river bed at a depth of 6 meters. The soil is clay having shear strength of $15tonnes/m^2$. The wall cohesive on the sides of pier could be taken as half of shear strength and the saturated density of 2 gm/cc. The rectangular pier is expected to carry a total load of 25, 000 tonnes including its own weight. If the depth of water in river is 5 meters, the factor of safety of pier against shear failure based on skempton’s approach is

1. 2
2. 3
3. 2.5
4. 2.7