Monitoring and analysis of soft foundation pit with braced structure of bored cast-in-place pile

The project is located in Changning District in Shanghai which is surrounded by lots of buildings. On the condition of silt clay, the retaining structure of foundation excavation is bored cast-in-place pile with interior bracing. The building settlement is related to the distance to foundation pit, the type of foundation, the soil parameter in foundation embedment and the water table out the pit. The maximum sedimentation occurs at the close building with concave curves within the duration of foundation construction, not reaching the bottom of foundation. The settling curve is converted from concave to convex, and formed straight ultimately. Dewatering plays an important role on the security of building pit construction, especially on the aspect of deformation of soil mass which recovers partly as water table recovers in post-construction period. The function of concrete bracing develops sufficiently, the first row of which is more powerful than the second. Deformation of retaining structure and soil mass are extremely small that the retaining structure controls the deformation of the foundation pit well.