Reliability Analysis Of Soil-nailing Wall And Related Research

With the development of society, the increasingly tense urban land, the number of foundation pit engineering gradually increases. Because of its economic, safe and convenience, soil nailing gradually becomes the main form of foundation pit. However, due to the uncertainty soil, the existing safety factor method of soil nailing design theory often can not guarantee the accuracy of the calculation. By the addition of the concept of a random variable, reliability analysis proposes a reliability index and uses the statistical probability of failure to express the foundation pit security, which is a good solution to the traditional safety factor method.At first, based on Double broken line method of the soil nailing, this paper analyzed the external and internal stability of the simplified method calculation mode, and established functions of reliability research. By comparing the advantages and disadvantages of several kinds of reliability analysis method, JC method is chosen as the basic method of the reliability analysis of soil nailing wall. And then this paper compiled and verified the JC method of reliability analysis program using Matlab software.In this study bootstrapping is used to characterize the uncertainty or variation of sample statistics. It is especially useful for model parameters with an unknown distribution and small sample size. Bootstrap method is also useful for estimating the uncertainty of soil parameters and determines distribution types and their mean and standard deviation of a random variable.In view of the Soil nailing wall instance, this paper analyses of the deformation monitoring data, then the reliability is calculated and analyzed. Under the same calculation model, when the safety factor method can not get the satisfactory result, the reliability index calculation is better for judging the safety of the supporting structure. Through the detailed analysis and calculation of each parameter’s influence on reliability index obtained:For three random variables γ,c and φ, the sensitive coefficient of φ is biggest, the sensitive coefficient of Y is the minimum; As the increase of the cohesive force’s and internal friction Angle’s mean, the reliability index of anti-slide stability, anti-capsize stability and internal stability calculation appear increases with the increase of the average trend; As the length of soiling nail and soil nailing wall height increases, the reliability index of the anti-slide stability and anti-capsize stability linearly increases and decreases, respectively. Finally, Study to solve the value of vehicle load in retaining and protecting for foundation excavation design. Based on the equivalent of horizontal resultant caused by the load on the retaining pile, according to the Boussinesq solution and the corner method in the theory of elasticity, the horizontal stress caused by the concentrated load and uniform load can be calculated; then the horizontal stress can be calculated by the finite element method with ABAQUS. Through the comparative and analysis, put forward the value of equivalent uniform load for the foundation pit support design on vehicle load.