Selection And Application Research On Shear Strength Index Of Soft Soil For Ultra Deep Foundation Pit In Wuhan

Taking the Zhonghai International Building ultra deep foundation pit in Wuhan Yangtze River I terrace as an object, the shear strength index of soft soil is obtained by using static pressure sampler, combining indoor soil test which include direct shear test (qq), consolidated quick shear test (cq), triaxial consolidated undrained test (cu) and triaxial unconsolidated undrained test (uu), and using the principle of mathematical statistics and comparing with qq shear strength index obtained by core tube. Meanwhile, a simulation analysis of Zhonghai International Building ultra deep foundation pit is carried out by 3D finite element software Midas GTS to study the variation of horizontal displacements of diaphragm wall and earth pressures of stratum mainly, and it is compared with measured data. It is found that using static pressure sampler for the perturbations of stratum is smaller than that of core tube. The shear strength index obtained by the static pressure sampler is more reliable. When selecting core tube shear strength index, the horizontal displacement of diaphragm wall and earth pressure of stratum are more closer to the measured data, cq index is followed. Proposal to select cu index for the first level excavation, and select cq index for the second and the third level excavations.