铁路隧道穿越山区倾斜多煤夹层施工稳定性研究

Research on the stability of inclined multi coal interlayer construction for railway tunnels crossing mountainous areas

文章依托瓮马铁路线南北延长线十标梅家巷1号隧道项目,基于现场地质勘探结果,利用Midas-GTS NX计算软件建立了铁路隧道穿越倾斜多煤夹层三维有限元开挖模型,探究了倾斜煤层不同间距(L=1.0d,1.4d,1.8d和2.2d)对隧道围岩变形规律和隧道衬砌受力特征。研究结果表明:当煤层间距L=1.0d时,隧道拱顶沉降呈扇形向上延展,最大拱顶沉降为22.99 mm,倾斜煤层对围岩变形影响范围呈了“断层式”扩散。当L=1.4d~2.2d时,倾斜煤层对拱顶围岩影响逐渐减小。受到煤层强度影响,围岩的软弱不均造成下伏基岩挤压变形,隧道仰拱最大隆起达到8.41 mm。隧道围岩最大变形值与隆起值均随煤层间距L的增加,呈指数衰减趋势。当L=1.0d时,隧道围岩承受来自沿垂直倾斜煤层方向的压应力,最大压应力为5.31 MPa,而拱顶方向所受压应力反而较小。隧道衬砌压应力随煤层间距的增加而逐渐减小,最大压应力主要分布区域趋近于掌子面。实际施工中应对沿垂直煤层方向的围岩加强监测与加固处理。

This article relies on the Mei Jiaxiang No.1 Tunnel project of the North South Extension Line of the Wengma Railway,and based on the results of on-site geological exploration,uses Midas-GTS NX calculation software to establish a three-dimensional finite element excavation model for railway tunnels crossing inclined multi coal interlayers.It explores the deformation laws of tunnel surrounding rock and the stress characteristics of tunnel lining under different spacing of inclined coal seams(L=1.0d,1.4d,1.8d,and 2.2d).The research results show that:When the coal seam spacing L=1.0d,the settlement of the tunnel arch crown extends upwards in a fan-shaped manner,with a maximum arch crown settlement of 22.99 mm.The influence range of inclined coal seams on the deformation of surrounding rock shows a“fault like”diffusion.When L=1.4d~2.2d,the influence of inclined coal seams on the surrounding rock of the arch gradually decreases.Affected by the strength of the coal seam,the uneven weakness of the surrounding rock causes compression deformation of the underlying bedrock,and the maximum uplift of the tunnel arch reaches 8.41 mm.The maximum deformation value and uplift value of tunnel surrounding rock both show an exponential decay trend with the increase of coal seam spacing L.When L=1.0d,the surrounding rock of the tunnel bears compressive stress from the direction of the inclined coal seam,with a maximum compressive stress of 5.31 MPa,while the compressive stress in the direction of the arch is relatively small.The compressive stress of tunnel lining gradually decreases with the increase of coal seam spacing,and the main distribution area of maximum compressive stress tends to approach the palm face.In actual construction,it is necessary to strengthen monitoring and reinforcement treatment of the surrounding rock along the vertical direction of the coal seam.