The Research On Limit State Design Method Of The Anchored Wall Under Different Rock And Soil Conditions

Anchored wall in railway is applied widely in the rock segment of general area,but anchor bar on soil is relatively small.However, with the sustained development of civil engineering, the application of anchor bar on soil is more and more, the anchor technology is gradually mature. The design of anchoed wall in the current standard is still using the allowable stress method. The allowable stress design method is a single safety factor design method with the combination of experience,but it can not guarantee the different structures of anchored wall with a consistent level of safety. Limit state design method is different to the allowable stress design method. Limit state design method is the improvement of engineering structure design method according to the shortcoming of ultimate strength design method. Limit state design method not only makes the design of anchored wall more rational and more economy, and it is contributed to the railway design specification of our country in line with international practices. In this paper, the limit state of anchored wall on sand stratum, clay stratum and rock stratum is studied and analyzed.Based on the extensive collection of relevant literature, theory analysis and programming calculation, the limit state design method based on reliability theory of anchor retaining wall in different design conditions is studied and analyzed:(1) The paper determineed the limit state equations and functions of anchored wall with the design and analysis of anchored wall on sand stratum, clay stratum and rock stratum. There are many factors affecting the stability of anchored wall. The single factor sensitivity analysis method is used to determine the main random variables affecting the structure involved in the limit state equations of anchored wall, including the internal friction angle of soil, the height of retaining wall, unit weight of soil, slope gradient, and so on.(2) According to the design method of the current standard, anchored wall on sand stratum, clay stratum and rock stratum was designed separately,and the calculation of the reliability index of the corresponding anchored wall was designed by the Monte Carlo method. The recommended value of the target reliability index of the anchored wall is given.(3) According to the reliability index of the target, The paper choose to use the general separation method to calculate the design conditions of anchored wall including rock stratum, sand stratum and clay stratum. We get the partial coefficients of each limit state design expression, and we compare comprehensive partial coefficients with the general safety factors of current codes. It initially forms the limit state design expression of the anchored wall.