Abstract：Abstract ： Research purposes ： Muzhailing tunnel of Lanzhou - Chongqing railway is located in the western part of Qinling Mountain, its geological conditions are very complex. There is a squeezing fault of f in the Dazhangou inclined shaft，and the strata are consist of slate，sandston and carbonaceous slate. The measured geostress results showed that this location is in a very high level of geostress state， the maximum horizontal principal geostress is nearly vertical to Dazhangou inclined shaft and the measured horizontal lateral pressure coefficient is 3. 79. Soft rock crushing， high geostress state, high horizontal lateral pressure coefficient and other factors led to the poor stability for the shaft. The construction process was simulated by FLAC3D to predict the deformation rules and mechanical rules. The simulation results would be useful to determine the construction parameters and in - situ monitoring for the tunnel in squeezing fault. Research conclusions:( 1 ) Combined with rock lithology conditions， geostress conditions， supporting structure and dynamic construction，deformation characteristics of the shaft，the large lateral deformation was caused by the interaction of high horizontal lateral pressure coefficient and poor geological conditions and other factors，but the main reasons of the large lateral deformation were recognized as uneven vertical and horizontal loads, extreme adverse load conditions of support structure. (2) Due to the interaction of primary lining and surrounding rock, the reinforced zone of surrounding rock was obviously enhanced and the original stress relaxation problems had been alleviated. Longitudinal tensile stress zone was occurred in the working face because there were not support measures. (3) The final stability of surrounding rock was reached by longer time because of the interaction of support structure and surrounding rock under the high initial geostress condition. In the final stable state, the surrounding rock was in a high compresives stress state. (4) The compresives stress of the primary lining in the arch part was 215.00 MPa, in an extremely high compressive stress state. But there was large tensile stress appeared in the side wall of primary lining. The primary lining was in a dangerous stress state. ( 5 ) The research results can be referenced to determine the construction parameters and in - situ monitoring for the tunnel in squeezing fault.
2016, Vol. 33 
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