特定场地下土工构筑物的几何可靠性分析

Geometric reliability analysis of geotechnical structures at a specific site

针对特定场地下土工构筑物的正常使用极限状态,采用近年发展的几何可靠性方法计算了多种构筑物的可靠度指标。考虑同一场地下的钻孔灌注桩、抗浮锚杆和CFG桩单桩加载变形测试曲线的离散性,各曲线回归参数呈现差异并可作为随机变量,进而探讨了各曲线回归参数间的相关性及联合分布特性。基于这些回归参数的联合发散概率密度等值线,即随机变量刚好达到极限承载能力状态,该几何可靠性算法可在随机变量的原始空间求得土工构筑物的可靠度指标。通过比对该几何可靠度指标与常规的一次可靠性算法成果,验证了该几何可靠性计算技术的可行性。计算表明,几何可靠性评价模型实施简便,易于被工程技术人员接受。

According to the limit state of geotechnical structures at a specific site under normal conditions of use, the reliability index of various structures is calculated by geometric reliability method that developed in recent years. At the same site, considering the discreteness of load-displacement curves of bored piles, anti-floating anchors and single CFG piles, the regression parameters of these curves show differences and can be regarded as random variables. The correlation and joint distribution characteristics of the site-specific regression parameters are discussed. Based on the joint divergence probability density contour(PDC) of these regression parameters, which means the random variables just reach the critical state of limit bearing capacity, the reliability index of geotechnical structures is calculated by the geometric reliability algorithm in the original space of random variables. The feasibility of geometric reliability algorithm is verified by comparing the geometric reliability index with the results calculated by conventional first-order reliability method. The results show that the geometric reliability evaluation model is simple to implement and can be easily accepted by engineers and technicians.