软岩大变形发生的边界条件及对策探讨

The Discussion of Boundary Condition for Large Deformation of Soft Rockmass and Its Control Countermeasures

研究目的:软岩大变形是长期困扰隧道施工的难题。以往研究多以强度应力比作为大变形预判和潜势分级的依据,但存在相当大的局限性和误判、漏判的可能性。本文从地壳运动出发,以区域地质条件中的地应力场、地层岩性、地质构造为主要支撑点,通过对大量典型隧道大变形地质条件的分析,定性地提出大变形发生的边界条件,并论证了通过试验段确定大变形支护参数的思想。研究结论:(1)大变形是人为改变内营力,导致地壳结构改变、地壳内部物质变位的构造运动;(2)大变形发生的边界条件主要有:最大主应力近于水平,薄层极软岩(R <5 MPa)占比较大,以及适宜的构造条件;(3)大变形隧道的支护参数应在施工中考虑地质条件、工艺工法及施工组织等因素,通过开展试验段确定;(4)本研究成果适用于软岩隧道大变形的预判和工程处理。

Research purposes： For a long time the large deformation of soft rockmass is a difficult problem in tunnel construction. In the past, the strength - stress ratio was often used as the basis of prejudging large deformation and potential classification, but there are the considerable limitations and the possibility of misjudgement and omission. Based on the crustal movement and the regional geological condition such as crustal stress field, formation lithology and geological structure, this paper analyzed the geological condition of large deformation of typical tunnels, proposed the boundary conditions for the occurrence of large deformation qualitatively, and demonstrated the idea of determining large deformation support parameters through test section. Research conclusions： （1） Large deformation was a tectonic movement that artificially changes the internal force, causing the crustal structure changing and the alteration of material in the earth ~ crust ; （2） The close to the horizontal maximum principal stress, very thin layer of soft rock （ R 〈 5 MPa ） and suitable tectonic condition were the main boundary conditions of larger deformation; （3） Factors such as geological conditions, process and construction organization should be considered in construction, and then determined the tunnel support parameters of large deformation by carrying out the test; （4） The research results can be applied to the prediction and engineering treatment for the large deformation of soft rockmass tunnel.