软弱围岩隧道超前支护加固形式研究

Research on the Forms of Advanced Support Reinforcement for Tunnels in Weak Surrounding Rocks

以某软弱围岩隧道为背景,通过数值模拟分析不同超前支护加固形式对隧道结构和掌子面稳定性的影响,并对不同的加固形式进行对比分析。分析结果表明:地表注浆加固距离隧道拱顶接近1.2 m时,对隧道拱顶沉降的控制效果显著提升;管棚支护加固区厚度越大,对隧道拱顶沉降的控制效果越好;采用地表注浆加固、管棚支护加固和联合支护时,掌子面的挤出变形趋势基本一致,中部的挤出变形值最大;采用联合支护时,掌子面中部的竖向挤出变形值最小,相比未支护、地表注浆加固和管棚支护加固竖向挤出变形值分别减小了约38.5%、27.3%和9.1%;在同一水平线上,掌子面的横向挤出变形值基本相同,隧道开挖断面距掌子面3 m处,掌子面中部的横向挤出稳定变形值长度较长,而隧道开挖断面距掌子面6 m处,掌子面中部的横向挤出稳定变形值长度较短。相关研究成果可对软弱围岩隧道支护提供借鉴。

Taking a tunnel in weak surrounding rocks as an example,the influence of different advanced support re-inforcement forms on the tunnel structure and excavation face stability were analyzed by numerical simulation.The different reinforcement forms were compared and analyzed.The analysis results indicate that when the distance be-tween the surface grouting reinforcement and the tunnel arch is close to 1.2 m,the control effect on the settlement of the tunnel arch is significantly improved;The thicker the pipe shed support reinforcement area,the better the con-trol effect on tunnel arch settlement;Under the surface grouting reinforcement,pipe shed support reinforcement and combined support,the extrusion deformation trend of the excavation face is basically the same,with the maximum extrusion deformation value in the middle;Under the combined support,the vertical extrusion deformation value in the middle of the excavation face is the smallest,which is reduced by about 38.5%,27.3%,and 9.1%compared with unsupported,surface grouting reinforcement and pipe shed reinforcement respectively;On the same horizontal line,the lateral extrusion deformation value of the excavation face is basically the same.At the place 3 m from the tunnel excavation section to the tunnel face,the length of the lateral extrusion stable deformation value in the middle of the face is longer.While at the place 6 m,the length is shorter.The relevant research results can provide reference for the support of tunnels in weak surrounding rocks.