Shao Huai Expressway Xuefeng Mountain Tunnel Rock Burst Prediction Of Large Deformation

The Xuefeng mountain highway tunnel, which is to be constructed, is the most deep-lying and longest tunnel in our country. Its geological conditions are more complex, the problems of rockburst and large deformation maybe its main problems of engineering geology. In this paper, the problems are elaborated in detail through this typical deep-lying highway tunnel research. The contents are discussed and main conclusions have been attained as follows:(1) The environmental conditions of engineering geology are discussed in detail.(2) Making use of some measure methods of field and indoor, the geostress status in the engineering rockmass has been ascertained and the systematic recognition of the geostress field in the area has been attained: The direction of a l in the area is N50?~86?W, and the included angle between the direction of o , and the horizontal surface is 25-45?on the whole.(3)Through the research of two-dimensional FEM for numerical analysis, the spread law of the geostress in the tunnel has been attained: 〢bout the surface of the mountainside, the direction of o , is parallel with the surface, but in the mountain the direction of o , is horizontal mainly. ㏕he spread of geostrss can be divided into twobands-------the equable geostress band and the effected band of epigentic-suefacereformation. 〢round fracture in the equable geostress band, there are geostress varied phenomena; there are local high geostress bands in the effected band , especially at the position of apparent landform chance .(4)Through rock mechanics experiment and the study fruit of Er Lang mountain highway tunnel, the mechanism research of rockburst is also discussed in detail, and the mechanism model of rockburst in established elementarily.(5)On base of the forgoing study and the research of tree-dimensional FEM for analysis, the predicting of rockburst in the tunnel has been given by using of two effective measures of forecasting-geological and complex forecast method and o 9 /Rb juding method. The result is that the probability of high tensity rockburst in the tunnel is non-existent and the probability of lowgrade and moderate tensity rockburst in the tunnel is existent.(6)The predicting of large deformation in the tunnel has been given by using of two effective measures of forecasting-geological and complex forecast method and tangential strain predicting method. The result is that the probability of large deformation in this tunnel is non-existent.