Settlement Calculation of Composite Foundation Reinforced with Stone Columns

Abstract

An axial compression was generated in a stone column under vertical loads on its top, and was often accompanied by a radial expansion against the surrounding soil near the top portion of the column. Considering this deformation characteristic of the stone column, an analytical solution for the settlement of the composite foundations reinforced with stone columns was presented. The load sharing between the column and the soil and the distribution of column-soil interfacial shear stresses was also incorporated into the solution. From the present solution, the vertical settlement and lateral bulging of the column under any applied loads can be evaluated at any depth. The validity of the solution was verified through the comparison with the measurement data and other existing analytical solutions. The influences of stress-concentration ratio, internal friction angle and cohesion of the surrounding soil, and the elastic modulus of the column on the deformations of the stone column were discussed. The load acting on the top of the column had a great influence on its deformations. Thereby, the accurate determination of the load distribution between columns and the surrounding soil was vital for analyses of settlement of composite foundations reinforced with stone columns during the design. The increase of the internal friction angle of the soil, the cohesion of the soil, and the modulus of the column had reduction effects on column settlements and bulging.