稳态渗流条件下盾构隧道松动土压力计算模型研究  

Calculation Model for Loosening Earth Pressure of a Shield Tunnel Based on the Influence of Steady Seepage

作　　者：王将 袁大军[1] 金大龙 牛紫龙 张兵[3] Wang Jiang;Yuan Dajun;Jin Dalong;Niu Zilong;Zhang Bing(Key Laboratory of Urban Underground Engineering of Education of Ministry,Beijing Jiaotong University,Beijing 100044,China;Shantou Suai Channel Construction Investment Development Co.,Ltd.,Shantou 515071,China;State Key Laboratory of Shield Machine and Boring Technology,China Railway Tunnel Group Co.,Ltd.,Zhengzhou 450001,China)

机构地区：[1]北京交通大学城市地下工程教育部重点实验室,北京100044 [2]汕头市苏埃通道建设投资发展有限公司,汕头515071 [3]中铁隧道集团有限公司盾构及掘进技术国家重点实验室,郑州450001

出　　处：《天津大学学报（自然科学与工程技术版）》2019年第A01期92-98,共7页Journal of Tianjin University：Science and Technology

基　　金：中央高校基本科研业务费专项资金资助项目(2018YJS106);国家重点基础研究发展计划(973计划)资助项目(2015CB057800);国家自然科学基金资助项目(51678037);国家自然科学基金联合基金资助项目(U1834208)

摘　　要：越江海或地下水丰富的盾构隧道在长期使用过程中渗水情况时有发生,由此引起的渗流场对隧道顶部荷载的影响是不容忽视的,但现有的松动土压力计算理论很少考虑渗流效应,对此提出了稳态渗流条件下的盾构隧道松动土压力计算模型.考虑盾构隧道处于稳态渗流状态,基于复变函数的映射变换,推导了隧道覆土内的孔隙水压力与渗流力表达式;引入小主应力轴旋转理论,得出了相应的侧压力系数计算公式;基于太沙基土拱效应分析模型,在渗流作用与主应力轴旋转效应分析的基础上,采用极限平衡法建立了竖向应力的微分方程,给出了盾构隧道顶部的有效松动土压力解析解答,分析了关键参数对计算结果的影响,并与有限差分软件FLAC的模拟结果进行了对比验证.研究结果表明:渗透系数相对值越大,隧道拱顶的有效松动土压力越大,但渗透系数相对值增大到一定程度后,该值的变化对于土拱效应影响很小;管片内侧水头恒定时,隧道拱顶的有效松动土压力随着渗流量的增加而减少;地表水头高度越大,隧道顶部的有效松动土压力越小;地表水头高度一定时,管片内侧水头高度的增加会削弱隧道顶部土拱效应;拱顶土体的位移越大,土拱效应越强;本文模型计算结果与FLAC模拟结果吻合良好,验证了本文模型的有效性.Water seepage occurs occasionally in the undersea shield tunnels or high groundwater level shield tunnels after long-term use. The influence of the seepage field on the tunnel top load cannot be ignored under any circumstanc.Seepage effects are rarely considered in the existing theory of loosening earth pressure.Therefore,this study proposes an analytical model to evaluate the loosening earth pressure,considering the seepage effects.The shield tunnel is in a steady seepage state;therefore,the pore pressure and seepage force around the tunnel are determined based on the conformal mapping of complex variable methods.According to the effects of the principal stress axes rotation,the lateral pressure coefficient of calculation model is obtained.Based on Terzaghi’s assumption,an analytical solution of effective vertical stress is deduced using the limit equilibrium method.Seepage and principal stress axes rotation are analyzed to obtain the analytical solution.The analytical model is verified via a parametric analysis and using a FLAC numerical model.The result show that when the relative permeability between the soil and lining is high,the effective stress acting on the tunnel is high;permeability coefficient variations have negligible influence on the effective loosening earth pressure when it goes beyond a certain value.The effective loosening earth pressure decreases with the increasing tunnel seepage rate;a higher surface water head leads to lower effective loosening earth pressure at the top of the tunnel.The effect of arching will be weakened with increase in the head height inside the segment;further,larger displacement of soil mass strengthens the arching effect.The theoretical results are consistent with the numerical results.

关 键 词：盾构隧道 松动土压力 渗流 主应力轴旋转 

分 类 号：TU432[建筑科学—岩土工程]