摘要
对于软黏土或残积土中的深基坑支护开挖,开挖后的地面沉降与基底隆起和挡墙变形密切相关,且受墙后地下水变化的影响显著。提出一种基于最新开发的简化对数回归模型的可靠性分析方法预测地面最大沉降,采用考虑土体空间变异性的方差缩减技术实现一阶可靠性方法(FORM),探讨了地面沉降超过既定阈值的概率,验证了方差缩减技术的高效性。通过分析关于空间平均及关键设计参数的影响发现,土体空间变异性会导致较高的破坏概率,挡墙的系统刚度、地面沉降阈值的大小、土体特性的变化系数以及地下水下降深度也对可靠性指标!有不同程度的影响,忽略其影响会导致不可靠的设计,较大的特征长度会导致较低的破坏概率和较高的!,同时考虑cu/σ′v和E50/cu的空间变异性会比单独考虑其中一项对!影响更大。
For braced excavations in deep deposits of soft clays or residual soils,the ground surface settlement behind the excavation is correlated with the extent of basal heave as well as the wall deflections and is also affected by the magnitude of the groundwater drawdown behind the retaining system.Reliability analysis based on a recently developed simplified logarithm regression model for estimation of the maximum ground surface settlement is presented.The first-order reliability method implemented with a variance reduction technique while considering soil spatial variability is employed to investigate the probability that certain ground surface settlement threshold is exceeded.This paper presents the effects of spatial averaging and the influence of several key design parameters including the stiffness of the wall system,the magnitude of the threshold ground surface settlement,the coefficient of variation of the soil properties,and the magnitude of the groundwater drawdown on the ground surface settlement.It is concluded that soil spatial variability results in a higher probability of failure(i.e.,a lower reliability index),without considering it would result in an unreliable design.A larger characteristic length results in a lower probability of failure and a higher reliability index.When the spatial variability of both the cu/σ′vand E50/cuare considered,the influence on!is more significant.
作者
章润红
GOH Anthony
周廷强
仉文岗
ZHANG Runhong;GOH Anthony;ZHOU Tingqiang;ZHANG Wengang(School of Civil Engineering,Chongqing University,Chongqing 400045,P.R.China;Key Laboratory of New Technology for Construction of Cities in Mountain Area of Ministry of Education,Chongqing University,Chongqing 400045,P.R.China;School of Civil and Environmental Engineering,Nanyang Technological University,Singapore 639798;School of Civil Engineering,Chongqing Three Gorges University,Chongqing 404130,P.R.China)
出处
《土木与环境工程学报（中英文）》
CSCD
北大核心
2021年第1期54-63,共10页
Journal of Civil and Environmental Engineering
基金
National Natural Science Foundation of China(No.52078086)
Program of Distinguished Young Scholars,Natural Science Foundation of Chongqing,China(No.cstc 2020jcyj-jq0087)
Chongqing Construction Science and Technology Plan Project(No.2019-0045).
关键词
地面沉降
基坑支护开挖
降水
空间变异性
方差缩减
ground surface settlement
braced excavation
groundwater drawdown
spatial reliability
variance reduction
