基于渐近法的城市近接地下空间有限土体土压力计算方法研究  

Study of the earth pressure for the limited soil adjacent to underground space in urban areas based on the asymptotic method

作　　者：陈桥枫 雷升祥[1,2] 赵伟 肖清华 李聪明[1] CHEN Qiaofeng;LEI Shengxiang;ZHAO Wei;XIAO Qinghua;LI Congming(Key Laboratory Transportation Tunnel Engineering,Ministry of Education,Southwest Jiaotong University,Chengdu 610031,China;China Railway Construction Co.,Ltd.,Beijing 100855,China;China Railway 18th Bureau Group Co.,Ltd.,Tianjin 300222,China)

机构地区：[1]西南交通大学交通隧道工程教育部重点实验室,四川成都610031 [2]中国铁建股份有限公司,北京100855 [3]中铁十八局集团有限公司,天津300222

出　　处：《铁道科学与工程学报》2022年第10期3025-3034,共10页Journal of Railway Science and Engineering

基　　金：国家重点研发计划资助项目(2018YFC0808700);四川省高校工程研究中心开放基金资助项目(SC-FBHT2022-05)。

摘　　要：地下工程拓建施工中,对基坑变形有较严格的控制要求,遇到有限土体宽度时,经典土压力的计算方法无法同时在安全和经济上满足工程需要。针对严格限制基坑变形情况下有限土体土压力的计算问题,以砂土地层为例,基于太沙基拱效应原理,考虑墙−土的切向摩阻力,通过建立水平薄层单元平衡微分方程,求解无水平位移有限土体的土压力。考虑支护变形和土压力的相互作用,针对限定水平位移条件下非极限状态时的有限土体,采用渐进法原理给出其土压力的计算过程,同时,根据基坑支护水平位移的控制指标,推导支护结构初始断面确定的方法。详细探究墙−土间摩擦角、有限土体宽度、支护结构变形量、地面超载、地下水等对有限土体土压力产生影响。研究结果表明:墙−土间摩阻力是有限土体发生土拱效应的重要前提;有限土体土压力随深度的增加呈非线性增加,但增加幅度逐渐降低,并趋于收敛;饱和静水场状态下,土拱效应弱化,土压力增大,且随着深度的继续增加,饱和土的土压力愈大于非饱和土的土压力。研究方法及结论可为拓建工程基坑支护的土压力计算提供新的思路和方法,也为城市地下空间拓建提供一定参考。In the extension construction of underground engineering,there is a strict control requirement for the deformation of excavation.When the width of soil is limited,the classical earth pressure calculation method cannot meet the needs of engineering safety and economy at the same time.To address the calculation problem of limited soil pressure under the condition of strictly limiting the deformation of excavation,the sandy soil layers were taken as the example,and the differential equilibrium equation of the horizontal thin-layer element was established to solve the limited soil pressure without lateral displacement based on the principle of Terzaghi arch effect and considering the tangential friction between wall and soil.Considering interaction between the deformation of support and earth pressure,for limited soil with the constraint condition of the horizontal displacement under non-limit equilibrium state,the asymptotic method was introduced to provide a process of the earth pressure calculation.Meanwhile,according to the control index of horizontal displacement of excavation,the method of determining the initial section of support structure was deduced.The friction angle between wall and soil,the width of limited soil,the deformation of support structure,the ground overload,underground water and others have significant impact on the soil pressure for limited soil.The results show that the friction resistance between wall and soil is an important prerequisite for the soil arching effect of limited soil.The soil pressure increases nonlinearly with the increase of depth,but the increasing amplitude gradually decreases and tends to convergence value.Under saturated hydrostatic condition,soil arching effect is weakened,and soil pressure is increased.With the depth increasing,the soil pressure of saturated soil is greater than that of unsaturated soil.The research methods and conclusions can provide a new idea and method for earth pressure calculation of the extension construction in the foundation pit engineering a

关 键 词：城市地下空间 有限土体 土拱效应 渐近法 土压力 

分 类 号：TU4[建筑科学—土工工程]