Experimental and numerical studies on vertical stress induced in single head-enlarged CDM columns under static load test

This paper presents a study on behavior of vertical stress profiles in head-enlarged (PF) and conventional CDM columns obtained from field static load test (SLT) and numerical analyses. Results from the numerical SLT on PF and CDM columns installed in ideally elastoplastic soil show that, due to the configuration of the column head, plastic failure points happen around the CDM column at lower load levels than that for the case of the PF column, and the load on PF column is showed to transfer to the soil more pronouncedly than that on the CDM column. The stress distribution and load – settlement curves obtained from the numerical analyses on the instrumented PF columns in general agree well with that obtained from the field tests. The induced stress profiles obtained from both numerical analyses and measured data show that there exists a major peak point of concentrated stress at the bottom of the cone section. This concentrated stress point may make the columns severely cracked and failed and this must be well aware in the design of bearing capacity of the PF columns.