Monitoring And Finite Element Analysis Of A Deep Foundation Pit In Hengshui

In recent years, with the development of the social progress, science and technology, the planar shape and support of the foundation pit engineering are becoming more and more complex, and the attention degree is becoming more and more important. Although after three decades of rapid development, the pit has accumulated a wealth of experience, but this experience only can provide some lessons, not be simply copied, because of soil conditions vary widely in different regions. The foundation pit in Hengshui are monitored and finite element analysis, which can effective control of pit deformation. So the pile is economical and safely and gain experience for the future of other similar projects in the region.This paper is aiming for a specific project examples deep pit in Hengshui City, by using Midas / GTS finite element software, established a three-dimensional finite element model of a joint action of soil and supporting structures to analyze the horizontal displacement of envelope pile wall and internal force and deformation of envelope pile wall and internal force and deformation of the support system and subsidence of soil outside and uplift bottom of the pit under the different conditions. And the simulated and monitored values analyzed. Finally using single factor analysis method, focuses on aspects of constitutive relation of soil, soil modulus, pile wall embedded depth and stiffness support stiffness respectivel by changing the three-dimensional finite element model. The main conclusions are as follows:1. The value of the horizontal displacement of pile foundation pit wall which has one support will be deepened with pile wall depth increases,.The displacement of envelope pile wall near the corners of the pit significantly smaller than other places, the displacement of the upper part of the support region of the envelope pile wall significantly smaller than the displacement of the lower part of the envelope pile wall. We can take advantage of that the corners effect is obvious characteristics in design of the foundation pit engineering to project cost savings.2.Subsidence global deformation tendency of soil outside the excavation is representative parabola layout form, and the maximum position is on 0.6 times depth from excavation wall, and the range of excavation on land subsidence is 2~2.5 times of excavation depth.3. Finite element analysis showed that with the value in the lateral support of foundation pit pile wall is mainly affected by the bottom of the excavation of soil modulus, bulk modulus of the soil from top soil pile foundation pit wall of the lateral value little effect.4. With the top of the pile wall enclosure supporting lateral support stiffness increases with the decrease, the bottom level of the lateral stiffness of the basic unsupported, support stiffness of the envelope of the horizontal displacement of the pile wall scope for a double excavation depth.5. In ensuring the safety of the situation pit,continuing to increase the depth of envelope pile wall influence the horizontal displacement little,but influence the uplift of pit deeply. With the stiffness of envelope pile wall meet safety requirements and the increase in stiffness, the reducing about the horizontal displacement of envelope pile wall becomes smaller.The above analysis results indicate that only the depth of pile and the stiffness of pile wall and envelope support in apposite proportion, can they play their role plently.So the foundation pit is further optimized.