ONE-DIMENSIONAL CONSOLIDATION TESTS OF CREEP DEFORMATION AND SECONDARY CONSOLIDATION CHARACTERISTICS OF SOFT SOILS IN SHANGHAI AREA

Based on a series of one-dimensional consolidation tests, the characteristics of creep deformation and secondary consolidation of Shanghai undisturbed soft soils were studied for different load ratios, different load velocity and overload pre-pressure. The test results showed that, creep deformation increased along with the increase of stress level and load velocity. For a constant stress level, the creep deformation decreased with the increase of load ratios. The creep deformation presented non-line characteristic and transferred from visco-elasticity to visco-plasticity while stress increased. When load ratios were high, the transformation was obviously. The parameter of Metchell one-dimensional model could be gotten by simulating experimental data and the curves tally with experimental data.It could be drawn from the analysis of testing data that for normally consolidated soils, the coefficient of secondary consolidation Ca wasn't affected by stress level and load ratios obviously, but it was related to load velocity closely. When the load velocity increased, Ca increased rapidly and then decreased slightly with stress rising. In addition, surcharge preloading can decrease the value of Ca and thereby is propitious for reducing the construction settlement.