Failure Mechanism Of Pit Construction Phase Contingency Plans For Research

The deep foundation pit projects get more and more along with the more exploitation and utilization to the city underground space. Because soil property and support form are different, there are all kinds of failure forms appear among support structure. The failure mechanisms of support construction are also very complex. It brings more difficulty to the theory research and the project utilization of foundation pit and affects the more development of deep foundation pit. In the past, most researches only analyze the failure reasons isolated and not considering of the influence of factors come with the construction. It's a dynamic gradual change course in foundation pit construction. The support structure is non-integrity bear force system in foundation pit construction and the force it bearded is changing with the construction of foundation pit and support structure. As a result, the factors that beget failure of foundation pit are also diversifying.Firstly, this paper summarizes the characteristics and reasons caused the engineering accident and the research actuality of foundation pit engineering accident and expatiates comprehensively on construction mechanics theory and the application on soil engineering through the research and analysis to a lot of literature of foundation pit engineering. Then, it analyzes and researches emphatically the pressure model and failure types and failure mechanism of the three support structure forms in common use in foundation pit engineering: cement treated soil column gravity retaining wall, cement treated soil column soil nailing and pile-anchor in construction phase based on the concept of construction mechanics. And then puts forward the emergency response plan of controlling foundation pit engineering accident initiatively in order to avoid bigness engineering accident and insure the foundation pit engineering carrying through safely and favoringly in every construction phase based on the failure mechanism in construction phase. Finally, it summarizes the failure mechanism of construction phase and the emergency response plan of foundation pit based on the construction mechanics and expects and forecasts the development trend of foundation pit in the future. The research production of the paper has better engineering meaning for preventing and reducing engineering accident of deep foundation pit.