富水软土地区束合管幕(UBIT)暗挖新工法的设计与工程实践

Design and Engineering Practice of a New Mining Method Using Underground Bundle Composite Pipe Integrated by Transverse Pre-Stressing in Water-rich Soft Soil Area

为解决富水软土地区无临时支撑、无土体加固、全断面挖土、超前支护与永久结构合一的暗挖建设难题,以上海市轨道交通武定路站1号出入口工程为背景,提出一种束合管幕暗挖新工法,即通过横向张拉预应力筋,将纵向顶进的离散的、小断面方钢管束合成可横向受力的整体结构。结合该工法结构型式特点,针对性地介绍了刚性板-弹簧单元耦合的接缝模型、C-T型锁扣构造、标准管与可满足接缝承受负弯矩的角部工具管构造、“双直并列”的横向预应力筋布置等设计关键技术,并通过开展抗剪、压弯节点试验与1/4结构足尺试验研究,揭示了束合管幕的受力性能重点在于接缝的承载性能与预应力筋的作用。工程实践及现场监测数据表明,应用情况良好,进一步验证了设计方案的安全性与适用性。

In this paper,the No.1 entrance and exit project of Wuding road station of Shanghai rail transit is taken as an example to solve the construction problems of the full-face mining method without temporary support and soil reinforcement,and with integration of advance support and permanent structure in water-rich soft soil areas.A new mining method with bundled pipe curtains is proposed,which can also be referred to as the UBIT(underground bundle composite pipe integrated by transverse pre-stressing)method,that is,by transversely tensioning the pre-stressed tendons,the discrete and small-section square steel pipes pushed in longitudinally are bundled into an integral structure.Combined with the structural characteristics of this method,the joint model using rigid plate-spring element coupling,the C-T type lock,the standard pipe,and the corner tool pipe that can meet the negative bending moment of the joint,the layout method of transverse pre-stressed tendon are introduced.And through the research of shearing,bending joint test,and 1/4 structure full-scale test,it is revealed that the performance of the bundled pipe curtain lies in the bearing performance of the joint and the effect of the pre-stressed tendon.Engineering practice and on-site monitoring data show that the application is in good condition,which further verifies the safety and applicability of the design scheme.