基于有限单元法的隧道抗水压衬砌结构设计

Structure Design of Tunnel Water-pressure Resisting Lining Based on FEM

研究目的:客运专线铁路隧道结构设计中往往会碰到水荷载作用计算难题,考虑抗水压衬砌结构设计仍然是隧道设计与研究热点之一。为检验隧道衬砌结构设计的安全性及防水性,有必要对抗水压衬砌设计结构进行内力计算。研究方法:针对金沙洲隧道特定地质条件和工程设计要求,采用基于有限单元法的荷载结构模型,对按围岩类别设计的3种隧道断面衬砌结构受力进行数值模拟。研究结果:研究得到了衬砌外水压力以及结构内力及分布特征,并验算了衬砌结构的安全系数。通过对计算结果分析验证,选出了各自围岩级别下合适的衬砌结构。研究结论:在全断面封闭排水的衬砌结构设计中,应着重考虑发挥混凝土的抗压性能;在富水区地下水头较大时,采用帷幕注浆法改善堵水圈的渗透系数,可有效降低衬砌的外水压力;选择仰拱外轮廓隅角半径、仰拱与曲边墙的连接处的半径以及仰拱厚度作为控制变量,可以改善衬砌结构受力特征。

Research purposes： During design on railway tunnels for passenger dedicated railway line,the calculation puzzle of water ballasting affect should be considered. So the lining structure design considering water press - resistant remain one hotspot of design and research on for tunnels. For checking security and water resistance of tunnel lining structure design ,it is necessary to verify structure force of tunnel lining design considering water press - resistant. Research methods：According to the specific geological conditions and the project design requirements of Jinshazhou Tunnel, the loading - structure model based on the finite element method is adopted to simulate structural stress of the lining structure for the design on three types of wall rock lining. Research results： Through the numerical simulation, the external water pressure of lining and the stress distribution are got; the safety factor of the lining structure is checked. By analyzing the results of tests, the proper lining structure of corresponding wall rock is selected. Research conclusions： In the design of lining structure with full face latch - up bailing, the resist compression performance of beton must be strongly considered. When the underground head is high in the region with vast groundwater, the external water pressure of lining can be lowed effectively by using drapery injecting plasm which can improve permeability. The feasibility that optimizing lining stress feature by control variance such as radius of invert external corner, radius of joint between invert and curve side wall, thickness of invert is examined and certificated through numerical simulation