基于KL展开法的基桩竖向极限承载力可靠度  

Reliability of Vertical Ultimate Bearing Capacity of Foundation Pile Based on KL Expansion

作　　者：谭晓慧[1] 姚玉川 林鑫 董小乐 Tan Xiaohui;Yao Yuchuan;Lin Xin;Dong Xiaole(School of Resources and Environmental Engineering,Hefei University.of Technology,Hefei 230009,P.R.China)

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009

出　　处：《地下空间与工程学报》2023年第4期1250-1258,共9页Chinese Journal of Underground Space and Engineering

基　　金：国家自然科学基金(41972278)。

摘　　要：为研究土体空间变异性对基桩承载特性和可靠度的影响,建立了空间变异土体中竖向基桩的数值计算模型,采用KL一阶可靠性方法进行了基桩在承载能力极限状态下的可靠度分析,验证了根据全局方差相对误差确定级数最优展开项数的合理性,分析了土体不排水抗剪强度Su与弹性模量E的空间变异性对竖向基桩可靠指标的影响规律。结果表明:在数值模拟中应考虑桩土接触面黏聚力强度随着Su随机场离散值的变化而变化;E的空间变异性影响基桩抗力与桩顶位移曲线的形状,但不影响基桩极限承载力及可靠指标的大小;可靠指标随着Su的变异系数及竖直自相关距离的增加而减小;在相同的离散精度条件下,单指数型与平方指数型自相关函数对基桩可靠指标的影响很小,但后者的计算量明显小于前者。To investigate the influence of soil spatial variability on the bearing characteristics and reliability of foundation pile,a numerical model of vertical foundation pile in spatial soils is developed.The KL-FORM is employed to analyze the reliability of foundation pile for the ultimate limit state of bearing capacity,which verifies the feasibility of determining the number of optimal expansion terms according to the global variance relative error.The influence of the spatial variability of soil undrained shear strength Su and elastic modulus E on the reliability index of vertical foundation pile is analyzed.The results show that the cohesive strength of pile-soil interface should be considered as a variable which varies with the discrete value of Su in the numerical simulation;the trend of the foundation pile resistance and pile top displacement curve is affected by the spatial variability of E,while the ultimate bearing capacity and reliability index is constant;the reliability index decreases with Su of coefficient of variation and vertical autocorrelation distance;and when the discrete accuracy is determined,the effect of exponential and square exponential autocorrelation functions on the reliability index is negligible,but the computational cost of the latter is significantly smaller.

关 键 词：空间变异性 随机场理论 基桩 自相关距离 可靠指标 KL展开法 

分 类 号：TU473[建筑科学—结构工程]