Subway Deep Pit Steel Brace Force Analysis Of The Factors

With the development of the subway construction in Beijing, the deep foundation pits become deeper and larger, moreover more and more deep foundation pits are near the downtown district. According to this phenomenon, a economic and effective supporting mode is used widely. This supporting mode combines the caisson pile and the steel bracing. Now controlling deform of the deep foundation pit is still a based-problem. How to control the deformation of the deep foundation pit effectively is the target purchased by both of the designing company and the construction company. For this combined supporting mode, the steel bracing force can affect the stability of steel bracing directly. So that is to say the stability of the deep foundation pit with this combined supporting mode can equivalent the stability of the steel bracing itself.Because there are some problems existing in some standards to the ultimate bearing capacity of the steel pipe, in this dissertation the main factors of the steel bracing force are discussed, and focus on the factors such as excavation, applying prestress, the mode of the junctions, the self-weight of the steel pile and the temperature of the environment. Also the course of the excavation is simulated through the analytic method and three-dimensional finite element analysis method. From this, the conclusions such as the reasonable value of the prestress, the effect of the self-weight to the steel bracing force, can be obtained by comparing the numerical solution and the finite element solution. At the same time, the method how to erase the effect created by the polytropic temperature of the environment can be obtained. The analytical method and corresponding conclusions gained have more important theoretical meaning and practical values in the design and construction of deep foundation pit.