Research On The Mechanism And Prevention Measures Of Large Deformation Of Soft Rock

Soft rock large deformation is a kind of harm of underground tunnel construction geological disaster, especially in complex geological environment grew up under the condition of tunnel construction in soft rock large deformation is often the key affecting the safety of tunnel construction schedule, construction engineering problems. Located in the southern region of sichuan province transition zone of Syria’s big railway park tunnel during construction is faced with the soft rock large deformation problems, this paper combined with the engineering practice to carry out the analysis of the formation mechanism of large deformation of surrounding rock and the prevention and control measures..In identification, on the basis of the tunnel engineering geology conditions, through the indoor experimental research and field engineering tunnel surrounding rock deformation failure mode and the analysis of its characteristics, this paper expounds the formation mechanism of large deformation of surrounding rock of tunnel, how to apply the principles of engineering geological analysis method and the tunnel engineering modern support theory, combined with the method of numerical simulation, studied the paradise of tunnel support reinforcement measures. Research results are as follows:(1) the entrance section of tunnel LeYuan park actual excavation formation lithology revealed as middle Leikoupo Formation limestone, marl, joint surface roughness, a micro Zhang, general rock breaking into pieces. The poor stability, therefore, to determine the grade of surrounding rock is v.(2) through the indoor experimental study on the rock, and paradise import period of some physical and mechanical parameters of surrounding rock tunnel, such as elastic modulus, poisson’s ratio, internal friction Angle, cohesive force, the uniaxial compressive strength and softening coefficient, etc., on the basis of indoor test and the rock compressive strength value of 16.78 MPa and the softening coefficient of 0.43, initially determined paradise import section of rock in soft rock tunnel, to soften rocks after softening action of groundwater.(3) in the previous studies on the basis of large deformation of surrounding rock type and mechanism, in combination with the geological background of the park surrounding rock large deformation, summarized park and large deformation characteristics of surrounding rock deformation failure mode, the paradise of tunnel surrounding rock deformation mechanism is analyzed, and put forward the mechanism of deformation of tunnel surrounding rock large deformation park:the softening effect of groundwater, structure deformation and stress of surrounding rock control type, among them the softening action of groundwater is a paradise of tunnel surrounding rock large deformation is the most important mechanism.(4) by using FLAC～3 d software simulation calculation under the condition of different measures of retaining structure of the deformation of surrounding rock reinforcement effect, concludes that only with flexible shotcrete or of support by rockbolt and shotcrete support measures can effectively restrain the deformation, need to increase the rigidity of the supporting structure, adopting steel arch frame, combining advanced small pipe compound support by rockbolt and shotcrete support measures to restrain the deformation. Paradise import tunnel deformation section were put forward.