昆明湖沼相软土地区基坑卸荷对地铁隧道的影响与保护措施  

Impact of foundation pit unloading on subway tunnels and protection measures in Kunming lake lacustrine soft soil area

作　　者：李霖 刘利先[1] 丁昊玉 LI Lin;LIU Lixian;DING Haoyu(School of Construction Engineering,Kunming University of Science and Technology,Kunming Yunnan 650500,China)

机构地区：[1]昆明理工大学建筑工程学院,云南昆明650500

出　　处：《工业安全与环保》2025年第3期55-61,共7页Industrial Safety and Environmental Protection

基　　金：上海交通建设总承包有限公司科研项目(KKF0202306265)。

摘　　要：为研究昆明湖沼相软土地区基坑卸荷对下卧既有隧道的影响,以昆明某地铁区段上方基坑开挖为工程背景,建立有限元模型,对隧道上方基坑开挖卸荷进行动态模拟,分析基坑卸荷过程中既有隧道结构位移和内力的变化规律,并探究不同保护措施的控制效果,结果表明:基坑卸荷完成后,隧道竖向位移远大于水平位移,施工过程中应重点关注隧道拱顶处的竖向位移;隧道变形呈现出水平收缩、竖向拉伸的“竖鸭蛋”形;隧道拱腰处轴力以及拱顶、拱腰、拱底处的弯矩受基坑卸荷影响较大,拱顶、拱底处轴力以及拱肩、拱脚处弯矩受基坑卸荷影响较小;基坑卸荷过程中,拱顶处位移最大且受力状态最差,施工中需加强监测;对于采取的保护措施,堆载和土体加固都能有效控制隧道的位移、变形及附加内力,堆载和土体加固的综合保护措施控制效果最好,土体加固措施控制效果明显优于堆载;不同卸荷比下各保护措施控制效果不同,实际工程可根据最大卸荷比选择合适的保护措施。To study the impact of excavation unloading in a soft soil region with a marshland-like subsoil on an exis-ting tunnel beneath it,a finite element model was established based on the engineering background of an excavation above a subway section in Kunming.A dynamic simulation was performed to analyze the displacement and internal force changes in the tunnel structure during the excavation unloading process and to explore the control effects of dif-ferent protection measures.The results show that:after the excavation unloading is completed,the vertical displace-ment of the tunnel is much greater than the horizontal displacement.During construction,particular attention should be paid to the vertical displacement at the tunnel crown.The tunnel deformation shows a"vertical egg shape"with hor-izontal contraction and vertical stretching.The axial force at the tunnel arch waist,as well as the bending moments at the crown,arch waist,and arch bottom,are significantly affected by the excavation unloading.The axial force at the arch crown and arch bottom,and the bending moments at the arch shoulder and arch foot,are less affected by the ex-cavation unloading.During the excavation unloading process,the displacement at the crown is the largest,and the stress state is the worst,requiring enhanced monitoring during construction.For the adopted protective measures,both surcharge loading and soil reinforcement effectively control the tunnel's displacement,deformation,and additional in-ternal forces.The combined protective measure of surcharge loading and soil reinforcement provides the best control effect,with soil reinforcement clearly outperforming surcharge loading.The control effects of different protection me-asures vary under different unloading ratios,and in actual engineering,the appropriate protection measure should be selected based on the maximum unloading ratio.

关 键 词：隧道 基坑卸荷 变化规律 数值模拟 堆载 土体加固 

分 类 号：U231[交通运输工程—道路与铁道工程] TU753[建筑科学—建筑技术科学]