Load carrying capacity of encased stone column in compacted pond ash bed

Abstract

The purpose of this work is to assess the suitability of reinforcing technique to improve the load carrying capacity of pond ash deposits through several laboratory model tests. In the 1st stage uniaxial compressive strength (UCS) tests were done on encased stone column (ESC) with varying slenderness ratio and relative density of compacted stone mass. It is found that load carrying capacity of stone column is directly proportional to the relative density (RD) of stone mass and inversely proportional to the slenderness ratio. In the 2nd series of test UCS test was conducted on ESC of slenderness ratio 2 and 3 reinforced with horizontal strip (HS) reinforcement made of galvanized iron (GI) and PVC mesh. In this case RD of stone mass and spacing between the strips (d, 0.5d, 0.25d, where d is the diameter of SC) was taken as variables. Circular GI strip placed at a spacing of 0.25d with RD 90% enhance the load carrying capacity by 11.44 times over the ESC. In the 3rd stage of experiment load test was conducted on pond ash bed reinforced with SC and ESC which is again strengthened with horizontal GI and PVC strip placed at different positions. Full encasement of SC reduces the bulging diameter and it carries more load than ordinary SC, embedded in pond ash bed. Further ESC reinforced with HS carry much higher load than the other configurations of reinforcement tried in this test. Further, the experimental results are compared with finite element analysis results using the software package PLAXIS and it is found that the ultimate load carrying capacity of stone columns for various reinforcement combinations are in good agreement with each other.