Effect of Underreamed Pervious Concrete Columns on Load-Carrying Capacity of Loose Cohesionless Soils

Abstract

Weak confinement governs the bulging failure of granular columns. Pervious concrete columns have granular columns like drainage with stiffness of concrete column are thus independent of the confinement from the weak surrounding soil can be treated as an alternative solution. Moreover, it is well established that under-reaming bulb enhances the bearing resistance to the pile shaft. Therefore, the present experimental and analytical study investigates circular pervious concrete column (CPCC) and under-reamed pervious concrete column (UPCC) in improving the bearing capacity of loose pond ash fill. CPCC and UPCC are constructed in a model pond ash fill subjected to vertical loading. The load-carrying capacity, settlement failure mechanism, and consolidation parameters were examined. Theoretical analysis for evaluating the load-carrying improvement factor (LCF) with nondimensional parametric variation of area replacement ratio (Ra), underreamed bulb ratio (Br), and length ratio of the column (RL) was also done. Efficacy of CPCC was also numerically studied (Plaxis 3D). Experimental results show that the vertical settlement is reduced by 52.8% with CPCC and UPCC. UPCC renders higher load-carrying capacity than CPCC. Both CPCC and UPCC undergo deformation at depth of 4D during failure. For the same area replacement ratio (Ra), the experimental and theoretically computed values are found in good agreement. The rate of consolidation is reduced from 53 to 23 days by using CPCC signifying its drainage potential.