The Subway Deep Foundation Pit Construction Safety Control Dynamic Index System Research

The research of safety index system about subway station deep foundation pit is one of the key subject in the construction of the subway. Confirm early warning value of deep foundation pit deformation control has significant value. The article background for research is 12 subway stations deep foundation pit in a city on southeast coastal of China. Take a research on early warning and then apply it in geological similar regions, such as Fuzhou. And the result was used to guide the information construction of Fuzhou subway. The primary content includes several parts as follows:(1) Summarizes the deformation character of foundation pit. The influence factors and calculation methods of deformation about foundation pit was Analyzed. Failure mechanism and safety criteria about retaining structure and surrounding environment was introduced.(2) Foundation pit safety index system contains the main evaluation index and secondary evaluation index. The main characteristic parameters judgment of foundation pit safety state was the horizontal deformation of retaining structure. Analyze the design horizontal distortion warning value of retaining structure. Collect the warning value of retaining structure subway from different areas and different vocations. The horizontal deformation of retaining structure about 12 subway station foundation pit in a city on southeast of China was statistical analyzed. Obtained the early warning index under 95% safety guarantee. And then explore the relationship between design warning value and measured value.(3) Through engineering analogy, the statistical results guiding the construction of Fuzhou subway. A subway deep foundation pit in Fuzhou was numerically simulated and deformation was analysis by the finite element software ABAQUS. Through the strength reduction method to analysis the foundation strength reserve.(4) Due to lack of material, unable to statistics the retaining structure of foundation pit accident history the biggest side (alert value).Through the numerical simulation, reduce the soil strength, simulation when the environment around the foundation pit was destroyed, the biggest horizontal distortion of retaining structure, and alert value was preliminary discussed.