Study On Support Technology And Ground Pressure Behavior Of Deep Soft Rock Tunnel

After mining in depth, the surrounding rock's deformation of soft rock tunnel become prominent, the surrounding rock is cracked seriously and the control to the stability of the surrounding rock is also difficulty particularly. In view of this, the support problems of deep soft rock tunnel had been as the research object in this paper. By the field survey and measure, destruction causes and styles of deep soft rock tunnel were analyzed and the cause and mechanism of floor heave was discussed. The strong age characteristic of the surrounding rock's deformation of deep soft rock tunnel was concluded. Based on measured data, methods were used to eliminate the centimeter-level system errors from the model and observation process. So, the measure precision was improved largely.Based on calastrophe theory, the mutation features of the surrounding rock's deformation and mechanics properties in engineering were analyzed. The concept of the critical depth was put forward after mining into depth. The stable criterion was obtained through the stability analysis the surrounding rock by this theory. Set pair analysis method was firstly adopted to evaluate on the surrounding rock quality about uncertain surrounding rock system and the set pair analysis model was also established.Based on chaos theory, the characters of non-linear dynamic of the surrounding rock's deformation process were discussed. The chaotic attractor dimension D and the largest Lyapunov index (E_max) were put forward to determine whether the deformation process of roadway is chaotic and the degree of chaos. On basis of the measured data of the tunnel displacement time series, the state space of the chaotic time series of tunnel displacement was reconstructed. The calculation method of chaotic attractor dimension D , the largest Lyapunov index (E_max) and the imbedding dimension was offered. The chaotic time series model to predict the surrounding rock's deformation of deep soft rock tunnel was established. The relative stability period of the surrounding rock's deformation was obtained. By numerical modeling method, the distribution laws of stress and displacement of deep soft rock after excavation were analyzed. The developing tendency of the surrounding rock's deformation was concluded. Based on plastic soften rockmass model, the nonlinear mechanical model of tunnel surrounding rock-support system was established. The analytical solution of the stress and plastic zone, elastic zone and crushing zone of tunnel surrounding rock. Based on the results of Mindlin, the calculation method of shearing stress and axial force of full-grouted bolt were obtained. The bonding mechanism of between full-grouted bolt and slurry, between slurry and surrounding rock were discussed.The feasibility using steel fiber concrete as a substitute for plain concrete in deep tunnel support under dynamic load was studied. Compared test of steel fiber concrete under static, dynamic and static-and-dynamical combination load were carried out. The optimal influence of fiber volume ratio fitting to support deep soft rock tunnel was obtained.On basis of laws of the surrounding rock's deformation and destruction, the reasonable support styles fitting to shallow tunnels and deep ones were put forward respectively. After numerical modeling and theoretical analysis, support parameters were optimized. The concrete measures to control and prevent floor heave were put forward. The industrial test results indicated that the applied support scheme was better, not only steel fiber concrete could control he surrounding rock's deformation, but also it could reduce working procedure and advance work efficiency greatly.