Research On Classification And Evaluation Of Epimetamorphic Wall Rock In Southeast Guizhou Tunnel

Classification of wall rock is always an important topic of the tunnel and underground engineerings. Because of different engineering geological conditions, the adaption of classification of wall rocks has been severely focused and queried. Thus, it is important for certain engineering circumstance to study classification of wall rock systemtically.It is analysed for epimetamorphic rock in southeast of Guizhou by field investigations and laboratory tests in this paper, including the physical-mechanical properties, destructional forms and main influencing factors of wall rock. And it is discussed to classify the wall rock dynamically in construction of tunnels. All researches will be not only profit for safety construction of XiaRong high way, but also useful for similar projects. The main results are as follow:(1) Judging from the investigation of landform, lithology and geologic body, it was concluded that the geological structures of tunnel site are relatively simple, and the geologic activities were not strong. The indoor tests of the basic physical-mechanical parameter for epimetamorphic is performed. It is mainly soft or relatively hard rock. It is investigated that the environmental engineering issues, on the basis of the construction site.(2) The types of deformation and failure of wall rock were analysed by observing work face of tunnel. In this region, wall rock are influenced by solid of rock and structural plane. There are some failure types of wall rock, such as block, bend the drum, arched top, collapse, relaxation and collapse.(3) By the geological prediction test, the typical radar reflectogram of geological phenomenon was obtained including the whole wall rock, fault zone, water-rich zone, fracture zone, etc.(4) According to the features and stability factors on wall rock, it can be confirmed that the basic classification factors are hardness degree of rock and integrated degree of rock mass. Modified factors are ground water and syntagmatic relations between the orientation of discontinuity and the axis of tunnel. Relevant relationship of respective index were analyzed. It is feasible to determine and evaluate the classification of wall rock in tunnel excavation by the geological forecast test and BQ method together.(5) It is obtained the convergence level of the range of epimetamorphic rock by monitore and measuration in the construction and post-analysis, which provide a standard to determine the degree of the wall rock.(6) The classification of wall rock was done by grey relational theory. Compared with the geological forest test and BQ method,the results of classification by grey relational theory are the same about 85%. It shows that the grey relational theory is feasible for the classification. But it is simple and efficient to utilize the advanced prediction test and BQ method together in determining the grade of wall rock on the basis of the feedback information.