基于可靠性分析的基坑土钉支护稳定性

土钉支护结构的稳定性取决于土钉与土体结构的相互作用过程。其相互作用过程的特征,一方面是具体包含了众多影响因素,如土体性质、土钉倾角、长度、支护深度等;另一不可忽略的重要方面是各种影响因素在具体开挖设计中的组合方式及其理论分析模型。因此,在理论分析模型方面,应用Sarma所提出的扰动力概念与条分法相结合,建立了考虑条间作用力影响的土钉支护结构稳定分析极限状态方程;在开挖支护设计方面,运用可靠度理论分析了各项设计参数(随机变量)及其组合方式对安全系数与可靠度影响的敏感性,以及安全系数与可靠度的相互关系。结合工程实例展示了理论分析模型的构成及其分析应用。

Evaluation on stability of trench strengthened with soil nail based on reliability analysis

The stability of soil nail structure was determined by the interaction between soil nail and soil mass.On the one hand,the characteristic of the interaction was influenced by many factors(maybe called as random variables in the mathematics),such as the properties of soil mass,length and inclination of soil nail,the strengthened depth and so on;on the other hand,the compound mode of those influencing factors in the design and the difference of theoretical model should not be ignored,So,a state equation of limit equilibrium,which was applied to stability analysis of soil nail structure,was set up considering the influence of inter-slice force and combining the idea of disturbance force of Sarma with slice method.In the design of timbering of excavation,the reliability theory was used to analyze not only the sensitivity of random variables,including index of reliability and safety factor,but also the relationship between them.The theoretical model and its application were shown in a practical project.