Stability Analysis Of Composite Soil Nailing Structures During Construction Period

With the development of urban construction in our country, the area and depth of foundation pits are increasing constantly, and the surrounding environments are also becoming more complicated, these put forward higher requirements for foundation pit supporting technology; soil nailing structure and composite soil nailing structure have been widely used in our country. People used to analyze the stability of foundation pits by safety factor methods based on the limit equilibrium theory. This method fails to consider the variability of practical geotechnical strength, it will bring disadvantages in theory and security risks in practice.In this paper, the reliability method is used to analyze the stability of foundation pit supporting structures, by seeking main failure modes, establishing limit state equations, solving the failure probabilities to evaluate the stability of structures. First, identify main failure modes of the structure system, use MATLAB to simulate failure criterion by Monte Carlo method. There is a certain relationship between different failure modes, so we can get correlation coefficients between various failure modes and the joint failure probability of structural system by the narrow boundary method. Then compare the results with safety factors obtained by FLAC3D or LIZHENG, analyze advantages of reliability method and evaluate the stability of the structure.In this paper, we study the specific working mechanism of soil nails, anchors and piles by analyzing the stress and deformation of composite soil nailing structure, in order to provide basis for the rational design of real structures. We analyze sensitivity of parameters to determine main random factors of the structure system, then put them into main consideration so as to reduce the number of parameters in theoretical analysis. In this way, we can improve calculation efficiency and provide basis for future practical projects.