Study On The Safety Evaluation Of The Pit Edge Load And Over Excavation To The Retaining Structure And Surrounding Environment

With a large number of city high-rise building construction, There are many pit edge load and over excavation phenomena on the influence of construction site and construction schedule,it puts forward the new challenge for foundation pit design.To the deep foundation pit excavation design theory is a new challenge, so for improved design calculation theory, improve the level of structure design is an urgent need.The problems in the construction is complicated, the pit edge load and over excavation is a common phenomenon in the urban deep foundation pit engineering, not only affects the construction progress, but also brought serious losses to the country and the people. For the common phenomena in these two kinds of construction.Using the finite element analysis software MIDAS/GTS combining with the actual soil layer information to analyze.This paper focuses on the following three points on the excavation of the existing problems:(1) Six common support structures and their application fieldsIn the second chapter,the advantages and disadvantages of each kind of supporting structures summarized.After comparison decide to use the combined support type.(2) Simulation and analysis of the pile edge under different kind of loadThe simulation of the pit internal force distribution and deformation law under five different combinations of deposit load. When the right deposit load is increased, the displacement and bending moment of pile at the right level is also to increase,At the same time, the settlement difference between the two sides of foundation pit is increasing,In order to make a preliminary preliminary judgment, whether the safety of the foundation pit and the different effects of the load. The influence of the structure and the surrounding under the pit edge load is also obtained.(3) Simulation analysis of different thickness of the pitThe simulation for the construction area soil conditions and the pile-anchor structure, simulate the influence of the foundation pit in different over excavation thickness to determine a reasonable excavation thickness under the support in the area.The influence of different thickness on the retaining structure and the geological condition of the pit is analyzed.Through the finite element simulation research accumulation of the material will produce a pile load, it has great influence on the deformation of the pile and the settlement of the surface, in the main area at a distance of about 0-20 meters; The increase of the thickness inevitably lead to horizontal displacement of the pile is increase, the surface settlement is also obvious.At the same time to determine a more reasonable over excavation thickness under the support in the area.