Study On Prediction Of Rockburst In Daxiangling Highway Tunnel

The DaxiangLing Tunnel which is constructing,is the controlled major project of highway from Ya'an City to Lugu County. Because of the comparatively complex geological condition which the tunnel is lain in, and is the existence of stress region of upland the rock burst maybe one of the main engineering geological problem of this tunnel. This thesis combines closely with the engineering practice of DaxiangLing Tunnel, chooses the study of rock burst problem as the mainline and make more comprehensive case study for the underground engineering roadblock. Study contents and conclusions acquired in this thesis are mainly included as follows:(1)The engineering geological environmental conditions of study area explicated. Study the regional geology and the regional stability, landform conditions, strata lithology and the engineering geological petrofabric, geological structure and its stress field evolution, the hydrological conditions and such in the study area.(2) The special stress status of rock mass in the project area are ascertained ,and the systematic recognition of developmental distribution rules of ground stress in the whole rock mass of tunnelling works are obtained through field and indoor testing. Research of this thesis has shown the mean direction of maximum principal horizontal stress is N55°W and the preferred orientation of principal horizontal pressure is N63°W.(3) The linear relation is lying in horizontal pressure and geostatic stress with the increase of buried depth of tunnel according to analyzing and calculating the drilling data; and the corresponding equation of linear regression is built in order to calculate the primary stress field of the tunnel.(4) The maximum tangential stress values of tunnel wall is acquired through numerical calculation and 3D-sigma finite element analysis of tunnel excavation.(5) The probability, section and intensity of rock burst emerging possibly during the DaxiangLing Tunnel excavation through applying the two methods such as prediction method of stress-strength ratio and fuzzy comprehensive evaluation on the basis of the foregoing research.