摘要
地裂缝是西安市典型的城市地质灾害,地下水位的变化是诱发地裂缝活动的重要因素。以西安地铁六号线暗挖段施工降水为研究背景,基于有限元数值模拟计算,分析了地裂缝场地施工降水引起的地表沉降规律和地层应力变化特征。计算结果表明:当地下水位下降时,地表沉降量上盘大于下盘,地裂缝带两侧地表存在差异沉降的现象,最大差异沉降量与地下水位下降深度近似呈直线关系;不同位置处地表的横向沉降呈现出"Z"形的变化特征,差异沉降区随地裂缝位置的变动而变化,且差异沉降量与横向地表位置近似呈二次函数曲线关系;地层竖向应力随着地下水位下降而增大,地裂缝位置处地层应力存在突变现象,上下盘应力影响区与地层深度近似呈三次函数曲线关系;基于分层总和法计算了地下水位下降时地表沉降量的解析解,并与数值模拟结果进行对比,发现两种方法计算结果基本一致,得到了计算地表最大沉降量的经验公式。研究结果可为地裂缝场地地铁隧道及其他地下工程安全施工提供科学指导。
Ground fissure is a typical urban geological disaster in Xi’an city,and the change of groundwater level is an important factor in inducing ground fissure activity. Taking construction precipitation in underground excavation section of Xi’ an Metro Line 6 as the engineering background,based on the finite element numerical simulation,the surface settlement law and strata stress variation characteristics caused by construction precipitation on ground fissure site were analyzed. The research results show that when groundwater level falls,the surface settlement deformation of the hanging wall is greater than that of the footwall,and there is a phenomenon of differential settlement on both sides of the ground fissure zone. The maximum differential settlement is approximately in a linear relationship with the depth of the groundwater level decline. At different positions,the lateral surface settlement curve shows a " Z" shape. The differential settlement area changes with the position of ground fissures,and the curve shows quadratic function between differential settlement and lateral position. In addition,with the groundwater level falling,the vertical stress of the stratum increases with the decrease of the underground water level,and there is a sudden change in the stratum stress at the location of the ground fissure and curve shows cubic polynomial function between stress affected area and depth. Based on the layer-wise summation method,the analytical solution of the surface settlement when the groundwater level falls is calculated. By comparing the calculation results with that of the numerical simulation,it shows a basic consistency,and the empirical formula for calculating the maximum surface settlement is obtained. The research results can provide scientific guidance for the safe construction of underground tunnel and other underground projects on ground fissure sites.
作者
王庆兵
黄强兵
闫钰丰
杨招
胡士伟
雷建
WANG Qingbing;HUANG Qiangbing;YAN Yufeng;YANG Zhao;HU Shiwei;LEI Jian(Beijing Municipal Road&Bridge Group Co,.Ltd,Beijing 100071,China;Department of Geological Engineering,Chang′an University,Xi′an 710054,Shannxi,China;School of Highway,Chang′an University,Xi′an 710054,Shannxi,China)
出处
《地质力学学报》
CSCD
2020年第2期221-231,共11页
Journal of Geomechanics
基金
国家自然科学基金项目(41772274,41372328)
北京市政路桥集团有限公司科研项目(220226180066)。
关键词
施工降水
地裂缝场地
数值模拟
分层总和法
地表沉降
地层应力
construction precipitation
ground fissure site
numerical simulation
layer-wise summation method
surface settlement
stratum stress
