高地应力板状软岩隧道大变形控制试验研究

Research on the Large Deformation Controlling of Soft Slate Formation Tunnel with High Ground Stress

研究目的:针对板状高地应力软岩隧道开挖的大变形问题,采用单层初期支护+双层二衬的结构形式进行支护,并进行现场试验,对初期支护、钢拱架以及两层二衬的变形与受力进行了测量,分析该支护结构在控制高地应力软岩隧道大变形方面的效果及该方案的可行性是本文的主要研究目的。研究结论:(1)传统的初期支护方式在控制高地应力软岩隧道的大变形方面效果不佳;(2)板状岩层的走向和岩层的倾角对高地应力软岩隧道开挖后的变形及受力会产生影响,一般来说,在垂直于板状软岩岩层(倾斜线)方向上的挤压力最大;(3)采用双层二衬结构,使初支与围岩一起产生变形而消除围岩的部分压力,第一层二衬起到强而稳定的支护作用并承担绝大部分的围岩压力,使第二层二衬受力很小而起到装饰作用,因此从高地应力软岩长期流变性的角度考虑,双层二衬结构对高地应力软岩隧道建成后的长期稳定性和安全运营具有很好的保障作用;(4)本研究成果可为类似工程的施工提供参考依据。

Research purposes:To solve the problem of large deformation in the excavation of soft slate formation tunnel with high ground stress,the support structure of one primary support+double-second lining is adopted for field test,and the deformation and stress of primary support,steel arch and two-layer second linings are measured.The main research objective of this paper is to analyze the effect of this support structure on controlling large deformation of soft rock tunnel with high ground stress and the feasibility of this scheme.Research conclusions:(1)The traditional primary support method is not effective in controlling large deformation of high ground stress soft rock tunnel.(2)Strike direction and dip angle of strata will have impact on the deformation and stress of soft rock tunnel with high ground stress.Generally,the extrusion pressure perpendicular to the direction of soft slate formation(inclination line)is the largest.(3)The double-second lining structure is adopted to make the primary support and surrounding rocks deform together and eliminate part of the surrounding rock pressure.Then the first second lining plays a strong and stable supporting role and bears most of the surrounding rock pressure,so that the second lining of second layer bears little stress and plays a decorative role.Therefore,according to the perspective of long-term rheological property of high ground stress soft rock,the double-second lining structure has a good guarantee effect on long-term stability and safe operation of high ground stress soft rock tunnel.(4)The research results can provide reference for the construction of similar projects.