考虑桩底沉渣的基桩竖向承载力目标可靠度  

Target Reliability Index Study of Vertical Bearing Capacity for Piles Considering Toe Debris

作　　者：徐志军[1] 李志谦 原方[1] 范量[1] XU Zhi-jun;LI Zhi-qian;YUAN Fang;FAN Liang(School of Civil Engineering and Architecture,Henan University of Technology,Zhengzhou 450001,China)

机构地区：[1]河南工业大学土木建筑学院,郑州450001

出　　处：《科学技术与工程》2019年第3期189-195,共7页Science Technology and Engineering

基　　金：国家自然科学基金(51608177;51578216);河南工业大学青年骨干教授培育项目(21420004);河南省属高校基本科研业务费专项(2017RCJH02)资助

摘　　要：桩底沉渣厚度超过一定数值后,会影响基桩尤其是端承桩桩端阻力的发挥,进而对承载力可靠度指标和目标可靠度指标造成不利影响。利用全概率计算公式推导出考虑沉渣桩的竖向承载力可靠度指标计算公式,并利用可靠度理论和数理统计方法给出了计算公式中每个参数的计算方法。在此基础上,推导出考虑沉渣桩的承载力目标可靠度指标计算公式。通过实例分析了不同沉渣参数(厚度、压缩模量、黏聚力、内摩擦角和泊松比)条件下,竖向承载力可靠度指标的变化规律。研究了沉渣桩出现概率对考虑沉渣桩的承载力可靠度指标和目标可靠度指标的影响规律。研究表明:沉渣的存在大大降低了沉渣桩的竖向承载力可靠度指标;沉渣厚度和压缩模量对可靠度指标有显著影响,黏聚力、摩擦角和泊松比对可靠度指标影响很小。沉渣桩的出现概率对考虑沉渣桩的承载力可靠度指标和目标可靠度指标有显著影响,尤其当概率值较大时,基础会出现一定的安全隐患。The tip resistance is contingent on the characteristics of toe debris when the thickness of toe debris is larger for piles,which can cause bad results to reliability index and target reliability index.Toemploy the total probability formula the computation formula of reliability index for vertical pile capacity considering the attendance of toe debris piles was derived.Each parameter in above formula is obtained according to reliability theory and mathematical statistics method.Based on case study,the influence regulations of the toe debris parameters(eg.thickness、compression modulus、cohesive strength、internal friction angle and Poisson s ratio)on reliability index of toe debris piles are captured.Then the probability of toe debris piles is taken into account to study the reliability index and target reliability index.The results show that the reliability index of toe debris piles greatly reduces due to the attendance of toe debris.The reliability index of toe debris piles is sensitive to the thickness and compression modulus of toe debris.However,the cohesive strength,internal friction angle and Poisson s ratio of toe debris have less influence on reliability index of toe debris piles.The probability of toe debris piles contributes greatly to the reliability index and target reliability index,especially when the probability of toe debris piles is large,the safety of pile foundation will be threatened.

关 键 词：全概率计算公式 桩底沉渣 可靠度指标 目标可靠度指标 承载力 

分 类 号：TU473.1[建筑科学—结构工程]