A Study on Behaviour of Cohession Less Soil with Square Plate

Many studies on the distribution of contact pressure have been made when a flexible or rigid footing is founded on soil. Many investigators have proposed bearing capacity theories assuming the footing to be rigid. But all theories have been based on the assumption that the footing will always be in contact with the soil. In this paper numerical analysis is carried out to separate foundations with partial contact with soil form those with full contact. The factors determining the contact of footing with the soil are plan dimensions, thickness and elastic properties of the material of the footing, modulus of sub grade reaction of the soil supporting it, the column to footing width ratio and eccentricity of loading. Multiple linear regression analysis is carried out to develop an equation for critical relative rigidity (CRR) in terms of the other parameters influencing it. Based on the equation, a single chart has been developed to find CRR for various combinations of the parameters influencing it. The conventional method of finding bending moment says that the maximum bending moment is independent of the relative rigidity of the footing (i. e. thickness of the footing and the modulus of sub grade reaction of the soil supporting it). But ANSYS 12.0 results show that bending moment depends on relative rigidity of footing also. Experimental work have been conducted to verify the values of maximum bending moment given by ANSYS. The results derived from the tests that are performed at the laboratory are typically a specific problem and they are difficult to extend, and to develop to field problems due to the different material or the geometric parameters used.