超浅埋小间距隧道穿越既有公路变形规律模拟研究

Simulation Study on the Deformation Law of a Shallow-Buried Tunnel with Small Spacing that Passes Under an Existing Highway

针对下穿既有公路的某超浅埋小间距隧道工程，对人口段的穿越施工过程进行了仿真模拟研究。研究结果表明，浅埋区左、右线隧道整体有左移的趋势，右线最大水平偏移量是左线的6—8倍左右；地表沉降由右洞拱顶地表向左洞延伸形成一沉降槽，右隧道拱顶地表沉降量最大；对存在偏压的浅埋小间距隧道，衬砌结构采用不对称几何形状设计比较有效；从中隔墙到偏压山体与地表交界处形成了明显的剪切带，应为施工期加强支护和监控重点区域。文中所给出的穿越里程段的偏压小间距隧道的变形规律、应力分布及中隔墙和衬砌支护结构的变形特征，以及既有公路路面的沉降规律等，对该工程的安全顺利施工和类似工程的设计与施工均有一定的积极作用。

The construction process of a portal section of a tunnel was simulated based on an existing shallow-buried tunnel with small spa move to the left, with cing that passes under a highway. The research resuhs show that： the left and right tubes tended to the maximum borizontal offset of the right tube being 6 to 8 times greater than that of the left tube; the ground seltlement extended toward the left tube from the crown of the right tube and a settlement trough was formed, with the maximum ground settlement oceurri geometric structure was most effective for a ng sh at the crown of the right tube; a lining design featuring an asymmetrical allow-buried tunnel with small spacing; and a shear zone was formed fi＇om the center pillar to the boundary of the massif and ground, therefore support and monitoring should be strengthened in this area. The obtained deformation law, stress distribution, and deformation characteristics of the center pillar and lining support structure, as well as the settlement law of the existing highway surface, will ensure the safe and smooth construction of the project.