Plastic deformation of soft clay under dynamic loading of deep foundation construction in Wuhan

With the rapid development of urban construction, the problems of ground subsidence and plastic deformation of soft clay under dynamic loading of deep foundation construction in Wuhan are urgent to be solved. Considering the issue of long-term ground settlement in the layers of silt and silty clay due to machinery vibration loading and repeated loading as well as the characteristics of structure, thixotropy and small strain of soft clay, the static triaxial test, resonant column test, field shear wave velocity test, ground micro-tremor test and vane shear test are taken to comprehensively analyze the mechanisms of ground subsidence and deformation under the machinery vibration loading and repeated loading. The test results show that the unconsolidated and undrained shear strengths are determined by the cohesive strengths of high-sensitivity silt and silty clay. The resonant frequency of the silt has a positive correlation with shear strain, but the dynamic shear modulus has a negative one. The resonant frequency and dynamic shear modulus of silty clay has a negative correlation with shear strain, but the damping ratio has a positive one. The filed shear wave velocity is determined by the structure, strength and distribution of soil stratum. The resonant frequency of three directions monitored by the ground micro-tremor test is much smaller than that of the resonant columns test. Based on the amplification effect of vibration wave peak acceleration in silt and silty clay, the formula for plastic strain of soft clay is suggested to be modified.