Stabilty reliability analysis of composite soil nailing structures with prestressed anchors
HUI Chen-yi1, 2, ZHU Yan-peng1, 2, YE Shuai-hua1, 2
1. Key Laboratory of Disaster Mitigation in Civil Engineering of Gansu Province,Lanzhou University of Technology, Lanzhou 730050, China; 2. Western Engineering Research Center of Disaster Mitigation in Civil Engineering of Ministry of Education, Lanzhou University of Technology, Lanzhou 730050, China
摘要 针对预应力锚杆复合土钉支护结构的稳定可靠性分析问题,以极限平衡理论为基础,建立了基坑稳定性分析安全系数求解公式和可靠性分析功能函数。以土体力学参数为作为随机变量,应用 Monte Carlo 重要抽样法计算了基坑稳定性可靠度指标和失效概率,通过工程实例进行了分析。分析表明：该稳定性计算公式计算的安全系数符合工程要求并且通过可靠性分析,因而使用该方法对复合土钉支护结构稳定性计算是有效的;基坑可靠性分析中,可靠度指标和失效概率Pf受土体黏聚力、内摩擦角与摩阻力的变异系数的影响较大,前者随变异系数的增大而减小,后者随变异系数的增大而增大;对于土体力学参数分布选型参数c采用对数分布,φ、qsik采用正态分布对可靠度计算分析比较合理。
Abstract：For the problem of reliability analysis of stability of composite soil-nailing supporting structures with prestressed anchors, based on the limit equilibrium theory, the safety coefficient formulas and reliability analysis functions for foundation pits are established. Then taking the mechanical parameters of soils as random variables, the stability reliability index and failure probability of foundation pits are calculated using the Monte Carlo importance sampling method. A project example is used for analysis. The results show that the formula for the stability calculation accords with the demands of engineering and the reliability analysis, so its use for calculating the stability of composite soil-nailing structures is effective. In the reliability analysis of the foundation pit, the reliability index and the failure probability are greatly influenced by the cohesive force, internal friction angle of soils and friction resistance of coefficient of variation. The former decreases with the increasing coefficient of variation, while the latter increases with the increasing coefficient of variation. For the selection of distribution of mechanical parameters of soils, the cohesive force of parameters takes logarithmic distribution, and the angle of internal friction and the friction resistance adopt normal distribution. The reliability of the calculation and analysis is quite reasonable.
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