Study On Dynamic Characteristics And Its Anti-pulling System Dynamic Reliability Of Prestressed Anchor Composite Soil Nailing In The Earthquake Process

Prestressed anchor composite soil nailing is comprehensive supporting technology with combination prestressed anchor bolting structure and soil nailing structure.This technology is convenient for construction, economical, reliable, and wide for the applicable conditions, so it is widely used in practical engineering and has a good application prospect. China has a lot of times earthquake disaster and slopes. Prestressed anchor composite soil nailing is an effective anti-seismic retaining structures, but its theoretical research lags far behind its practical application. Now this new type slope supporting technology was used more and more. Therefore, study of prestressed anchor composite soil nailing in the earthquake process has greater practical value. The anti-pulling system dynamic reliability of prestressed anchor composite soil nailing is a time-dependent stochastic process under earthquake action. As research in this area is currently insufficient, the paper is mainly based on the fluctuation characteristics of the earthquake and randomness of the interfacial bond strength to analyze the anti-pulling system dynamic reliability.The main research work of this article are as follows:(1) The influence of fluctuations characteristic for slope supported by prestressed anchor composite soil nailing is analyzed.On the basis of analyzing the interaction of prestressed anchor and soil nail, the three-dimensional finite element analysis model considering the earthquake actionis is established by MIDAS / GTS finite element analysis program for a slope engineering examples. And the results under static conditions, quasi-static and dynamic time history case situation are compared.(2) Study on dynamic Characteristics of slope supported by prestressed anchor composite soil nailing. To analyze acceleration amplification effect of slope supported by composite structure, different seismic intensity is simulated by changing input values of peak acceleration in the model. And to analyze influence of axial force for other soil nailing and prestressed anchor as a result of failure of single soil nail, the analysis results of two models is compared with the axis force in two models.(3) Evaluation method of the anti-pulling system dynamic reliability for prestressed anchor composite soil nailing under earthquake is established. On the basis of dynamic characteristics of slope supported by prestressed anchor composite soil nailing and system reliability basic theory,the evaluation method of overall anti-pulling system dynamic reliability considering the fluctuation characteristics of the earthquake and randomness of the interfacial bond strength is established by Duration FEM. It is able to make an assessment of overall anti-pulling reliability of the design of composite structures under dynamic action. The method is applied to numerical example, and the calculation results were compared with results by traditional the Monte Carlo method.(4) Optimization method of single row of soil nailing is proposed on the basis of the standard value of index of dynamic reliability. Due to the finite element calculation does not consider the exit mechanism,the standard value of dynamic reliability index of soil nailing and anchor is proposed for judgment of failure state in order to ensure the accuracy of the overall anti-pulling reliability of composite structure.The result showed that, the interval evaluated by the method proposed in the paper is reasonable. The result is able to meet the engineering application. Therefore, the method is feasible, simple and practical. And the research conclusions in this paper has good reference and guide for dynamic reliability analysis of other similar project.