考虑卸荷变形模量的坑底回弹变形计算方法  

Calculation methods for rebound deformation of foundation pit bottom considering unloading deformation modulus

作　　者：陈晓 董建华[2] 董和平 汤小林 田文通[2] CHEN Xiao;DONG Jianhua;DONG Heping;TANG Xiaolin;TIAN Wentong(Gansu Construction Investment Civil Engineering Construction Group Co., Ltd., Lanzhou 730050, Gansu, China;College of Civil Engineering, Lanzhou University of Technology, Lanzhou 730050, Gansu, China)

机构地区：[1]甘肃建投土木工程建设集团有限责任公司,甘肃兰州730050 [2]兰州理工大学土木工程学院,甘肃兰州730050

出　　处：《地震工程学报》2021年第5期1134-1141,共8页China Earthquake Engineering Journal

基　　金：甘肃建设科技攻关项目(JK2018-40,JK2019-08)。

摘　　要：针对基坑开挖卸荷导致坑底土体回弹变形问题,考虑开挖卸荷过程中土体弹性模量随着卸荷应力路径变化的特征,推导在卸荷应力路径作用下土体变形模量的计算公式,考虑基坑的开挖为地表以下基坑开挖面处应力的变化,基于Mindlin应力解计算矩形基坑开挖卸荷引起的坑底土体附加应力,采用分层总和法计算基坑开挖引起的坑底土体的回弹变形,结合已有文献中的工程实例,采用该方法计算开挖引起的坑底隆起变形,并与实际监测数据对比分析表明,该方法能够有效预测基坑开挖引起的坑底隆起变形,能够作为基坑开挖坑底隆起变形的一种有效预测方法。Aiming at the rebound deformation of soil at the bottom of foundation pits caused by excavation unloading,the characteristics of soil elastic modulus changing with the unloading stress path during excavation was first considered,then the calculation formula of soil deformation modulus under unloading stress path was derived.Considering the change of stress at the excavation surface of foundation pit below the ground surface,based on the Mindlin stress solution,the additional stress of soil at the bottom of rectangular foundation pit caused by excavation unloading was calculated.The rebound deformation of the soil at the bottom of foundation pit caused by excavation was calculated by the layer-wise summation method.Combined with some engineering examples in the existing literature,the heave deformation of pit bottom caused by excavation was calculated by this calculation method,then the calculation results were compared with the actual monitoring data.The results showed that the proposed method can effectively predict the heave deformation of pit bottom caused by excavation,thus it can be used as an effective prediction method in this field.

关 键 词：卸荷模量 MINDLIN 坑底隆起变形 分层总和法 

分 类 号：TU448[建筑科学—岩土工程]