基于贝叶斯方法的软土深基坑不确定性位移反演分析  

Probabilistic method for displacement back analysis of deep excavations in soft soil based on Bayesian method

作　　者：林东 郑俊杰[2] 薛鹏鹏 李子骞 彭荣华 LIN Dong;ZHENG Junjie;XUE Pengpeng;LI Ziqian;PENG Ronghua(China Railway SiYuan Group Southwest Survey and Design Co.Ltd.,Kunming 650206,P.R.China;Institute of Geotechnical and Underground Engineering,Huazhong University of Science and Technology,Wuhan 430074,P.R.China)

机构地区：[1]中铁四院集团西南勘察设计有限公司,昆明650206 [2]华中科技大学岩土与地下工程研究所,武汉430074

出　　处：《土木与环境工程学报（中英文）》2024年第3期52-60,共9页Journal of Civil and Environmental Engineering

基　　金：中铁第四勘察设计院集团有限公司科研课题(2020K144)。

摘　　要：在深基坑开挖工程中,使用合理的土体力学参数计算地连墙侧移对优化基坑支护方案以及降低工程风险至关重要。然而,受地层分布不均、土工试验误差等因素的影响,土体参数常表现出明显的不确定性,该不确定性降低了地连墙侧移计算结果的可信度。鉴于上述问题,提出一种基于贝叶斯参数更新框架和现场监测数据的软土深基坑土体参数反演方法。该方法采用GA-BP神经网络建立数值分析模型中土体参数与地连墙侧移的隐式函数关系,并结合现场监测数据建立土体参数的贝叶斯反分析模型。采用该方法对某深基坑工程进行分析,验证了方法的可行性。分别采用地连墙的最大侧移值和多点位移值作为指标进行土体力学参数反演,并分别使用更新后的土体参数预测基坑开挖的最终侧移值。研究结果表明:与不更新土体参数相比,更新土体参数后土体参数变异系数变小,得到的结果与后续施工步下的监测结果更吻合;使用多点观测值进行土体参数更新的预测效果显著优于仅使用最大位移值时的效果。In deep foundation excavation projects,using reasonable soil mechanical parameters to calculate the lateral deformation of diaphragm wall is essential to optimize the support design and reduce engineering risks.However,the soil parameters are generally affected by the uneven distribution and geotechnical testing errors,which often show obvious uncertainties and reduce the credibility of the lateral deformation calculated of diaphragm walls.In view of the considerations above,this paper proposes a back analysis method of soil parameters based on Bayesian parameter updating framework and site monitoring data.This method uses GABP neural network to establish the implicit function relationship between the soil parameters and the diaphragm wall lateral displacement in the numerical model,and combines the site monitoring data to establish the Bayesian back analysis model of the soil parameters.This method was used to analyze a deep excavation project,and the feasibility of the method was verified.The maximum lateral displacement and multi-point displacement value of the diaphragm wall were used as indicators to invert the soil mechanical parameters,and the updated soil parameters were used to predict the final lateral displacement.The results show that compared with the non-updating soil parameters,the variation coefficient of soil parameters decreases after updating,and the obtained results fit with the monitoring results better in the subsequent construction steps;the prediction effect of using multi-point observations for soil parameter updating is significantly better than that when only the maximum displacement value is used.

关 键 词：深基坑 土体参数 位移反分析 贝叶斯方法 马尔科夫链蒙特卡罗模拟 

分 类 号：TU753.1[建筑科学—建筑技术科学]