Experimental and theoretical analysis of the bearing mechanism of the novel underground pipe curtain support system

The existing pipe curtain support systems can effectively control the settlement caused by the construction, but there are problems such as high precision requirements for pipe jacking, complicated connection between pipes and high self-weight, which increase the construction difficulty and period. A novel pipe curtain support system was proposed in this paper, which mainly consisted of the cutting steel pipe, connecting steel plate and section steel (named CSP-SS method). First, the construction steps and applicability of this support system were described in detail. Then, four experiments were conducted to examine the failure mode of this support system and the impacts of stiffening ribs, connecting steel plate thickness, and steel pipe cutting height on the bearing performance. Subsequently, the calculation models of the ultimate capacity and bending stiffness of the pipe curtain were established. Finally, the application process of the calculation model in actual engineering was given. Experimental and theoretical analysis demonstrated that installing stiffening ribs increased the ultimate capacity by 5.88 %, while reducing the pipe cutting height significantly enhanced the flexural stiffness by 38.37 %; in contrast, the thickness of the connecting steel plate had a marginal influence (stiffness reduction less than 7 %). The proposed calculation models for ultimate capacity and flexural stiffness showed good agreement with test results, with average errors of 8.34 % and 9.2 %, respectively, and the theoretical predictions were generally conservative, which is conducive to the safety design of the project.