Effects of Formation of Voids on the Behavior of Prestressed Reinforced Granular Beds overlying Weak soil: Fid-Bau Portal

Effects of Formation of Voids on the Behavior of Prestressed Reinforced Granular Beds overlying Weak soil

Shivashankar, R. / Jayamohan, J.

In this paper the results of finite element analyses carried out to investigate the effects of formation of voids on the behavior of a square footing of size 'B' resting on a prestressed reinforced granular bed (PRGB) overlying weak soil are presented. The parameters varied are magnitude of prestress, thickness of granular bed (H), depth of void below the footing (y) and eccentricity of the void (x). The diameter of the void is taken as equal to 0.6 times the width of footing for all the cases. It is observed that when the thickness of granular bed is equal to B, the reduction factor varies with the cube of (y/B) and when the thickness of granular bed is equal to 2B, the reduction factor varies with the square of (y/B). When the void is located at a depth more than twice the width of footing, from the base of footing, its effect is observed to be negligible. Based on the results of finite element analyses obtained, the following conclusions are made on the behaviour of prestressed reinforced granular beds overlying weak soils with voids: (1) The presence of void in soil causes a considerable reduction in bearing capacity. (2) It is observed that prestressing the reinforcement can decrease the reduction in bearing capacity of Reinforced Granular Beds overlying weak soil with voids. (3) The presence of void has only a negligible effect when it is at a depth of more than 2B from the base of footing. (4) It is observed that when the thickness of granular bed is equal to B, the reduction factor varies with the cube of (y/B) and when the thickness of granular bed is equal to 2B, the reduction factor varies with the square of (y/B). (5) The reduction factor decreases with eccentricity of the void.