Analysis Of Stability And Mechanical Deformation Of Xufu Garden Foundation Pit With Pile-anchor Retaining Structure

With the development of city construction, the number of the foundation pit engineering becomes larger and larger. Foundation pit supporting structure is often used as a temporary structure and the safety reservation is little compared with permanent structure. But the foundation pit engineering is generally located in the city and there are various buildings, pipelines, roads around. It will cause a heavy loss of life and property in the case of a possible accident. Therefore, it is particularly important to guarantee the safety of the excavation and avoid the engineering accident. This paper takes Dongguan City Xufu Garden foundation pit project as the background, considering the construction process of the excavation, the force and displacement of each condition are calculated firstly by the Lizheng software. Reinforcement calculation is done according to the internal force value. And the overall stability, anti overturning stability and anti uplift stability of the foundation pit has been checked.We mainly do the research based on three modules of finite element software GeoStudio : first of all, the construction process of Xufu Garden foundation is simulated in the SIGMA/W module. The deformation and stress-strain characteristics of foundation pit and retaining structure in the excavation process is analyzed. Secondly, dynamic response of the foundation in horizontal earthquake is analyzed in the QUAKE/W module. 11 records are set from the slope top to pile bottom and the variation of the displacement, velocity, acceleration is analyzed. Finally, in the SLOPE/W module, The safety factor of the excavation process is calculated and the effect of soil parameters is explored. Then the safety coefficient of excavation in horizontal earthquake of 0.05 g is calculated with quasi-static method. The impact of the soil nail length change on the safety coefficient is analyzed. And based on the dynamic stress in the QUAKE/W module, the time curve of safety factor of foundation pit is obtained.Through the numerical simulation of the construction process of foundation pit, it is found that the shape of horizontal displacement curve of retaining piles which is moving towards the inside pit is "small at both ends and big in the middle ". The horizontal displacement of pile top is reduced by about 1.5mm with each growth of 50 kN locking force of the anchor. In practical engineering, engineer should choose the appropriate locking force based on the control displacement value required. Through the analysis of stress and strain of soil, it is found that soil near the pit corner and pile bottom come into the plastic state easily. In order to reduce the range of plastic zone and the hidden danger, planners should ensure depth enough of the retaining piles, and pay attention to reinforcing and monitoring the soil in passive area when design the same type of supporting. Analysis of Lizheng software and finite element software shows, this Engineering design meets the use requirements. The process and results of simulation in this paper also provide valuable reference for rational design of the similar problems.