Deformation Characteristics Of Foundation Pit In Sandy Soil

Since the reform and opening up, China’s economy has developed rapidly, and the scale of the urbanization construction has been increasingly expanding. Relying on their unique geographical advantages and comfortable living environment, coastal cities become the first choice for people to gather. However, the concentration leads to a growing shortage of urban space. Making full use of underground space to improve the urban infrastructure construction in the city has become an essential part of the city development. And a lot of complex and deep foundation pit engineerings have emerged in this process. As an important feature of coastal cities in engineering geology, sandy soil base condition is common in those areas. Researching on the deformation of the sandy soil foundation engineerings is of great value for the construction of coastal cities in the future.This paper is based on engineering examples in Haikou of TianLi three-star hotel and serviced apartments and offices foundation pit engineering, HeXin Square foundation pit engineering and MeiHe community foundation pit engineering. In the course of their construction, the foundation pits are monitored in site, and the deformation characteristics of sandy soil foundation pit are summed up. Three-dimensional finite element is established of the building envelope in MeiHe community foundation pit, and the simulation results are compared with the results of the monitoring. Research and the main results obtained in this paper are as follows:(1) This paper summarizes the deformation characteristics of foundation pit engineering summed up by predecessors. In sandy soil foundation pit, the deformation caused by excavation of foundation pit mainly contain the deformation and displacement of the supporting structure, the settlement and displacement of the soil behind the supporting structure, the rebound and uplift of the soil in the bottom of the foundation pit and the change of groundwater level.(2) In sandy soil foundation pit retained by row piles retaining structure, the top horizontal displacement of retaining structure has the characteristics with the largest value in the mid-span and the smallest value in two ends. The vertical displacement changes little and the main sphere of influence to surrounding environment lies in1.5times the excavation depth away from the edge of the foundation pit.(3) In sandy soil foundation pit of slop excavation, the horizontal displacement variation in top of the slope is uniform. The vertical displacement change evidently and the main sphere of influence to surrounding environment lies in2times the excavation depth away from the edge of the foundation pit. (4) The integral three-dimensional model of the building envelope in MeiHe Cell foundation pit is established, and it turns out that the simulative deformation characteristics and the measured deformation characteristics are similar.