Question

Q2. Assume a rigid strip footing is constructed on a normally consolidated clay layer under a uniformly distributed vertical load. The depth of footing is zero and the water table is a few metres below the surface ground. The average shear strength parameters of the clay layer are:

• At the beginning of loading: f_u = 0, c_u = 50 kPa
• Long time after loading:, f’ = 25° and c’ = 0 kPa

Will the bearing capacity of this footing change, if the water table rises to the ground surface? Briefly explain.

Note: No calculation is required. Assume the ground and the base of footing are horizontal.

Answer 1

*change in moisture content of the soil effect the bearing of the soil

*From the research it is observed that if the water table is at a depth less than width of the footing from the bottom of the bottom of the footing will reduce the bearing capacity.

*If the soil is completely submerged it's ability to withstand the load changes. This results in decrease in the bearing capacity of the soil. In this case submerged unit weight of soil is considered for calculation of bearing capacity and this unit weight is less than the dry unit weight or bulk unit weight.

*Water table corrections are used to find bearing capacity of the soil when water table is above the footing or just below the base of the footing.