关键词: 富水软土地区, UBIT工法, 束合管幕, 预应力, 暗挖

Abstract: 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.

Key words: waterrich soft soil area, underground bundle composite pipe integrated by transverse prestressing method, bundled pipe curtain, prestress, underground excavation