Use of deep cement mixing to reduce settlements at bridge approaches

Differential settlements between a bridge and the backfill behind the abutment have been a major problem in the construction of expressway embankments over a soft clay foundation. Deep cement mixing (DCM) columns with varying lengths were used to reduce such differential settlements along the Fu-Xia Expressway, Fujian Province, China. The performance and the feasibility of the DCM method were investigated in a trial embankment constructed prior to the actual construction This paper presents the results of the instrumentation including total settlements, multipoint settlements, soil pressures on both the DCM columns and soil surface, pore-water pressures, and lateral movements obtained from in situ monitoring. The strength of the soil cement from laboratory mix tests and from in situ quality control tests on DCM columns is presented in the paper. Study results indicate that DCM columns with varying lengths were a simple and effective method to reduce the total and differential settlements from a soft clay foundation at a bridge approach.