Study On The Large Deformation And Controlling Technology Of Faultin Tunnel

In the Qiandiao No.3 tunnels of Yakang Expressway, there are two groups of extremely developed tectonic joints in the rock body, and the local rock is cut into blocks, which leads to rock stability of the surrounding rock of tunnel, there are off the block and the phenomenon of slip.Therefore, in such rock mass tunnel construction, the surrounding rock stress,deformation and failure mode will be very complex, once the construction method or process is unreasonable, may cause tunnel collapse or even cause major engineering accidents.In this paper, based on the important and difficult problems in the tunnel construction of the tunnel,which is caused by the large deformation of the surrounding rock, the authors use the method of literature research, theoretical analysis, numerical simulation and field measurement to study the tunnel crossing the fractured rock mass And the mechanics behavior of the fault, the catastrophic mode and its control technology of the interface between the fault zone and the normal zone, the main research work and achievements are as follows:1.Based on the literature review and the actual engineering of Qiandiao No.3 tunnel of Yakang Expressway, the excavation method of tunnel construction in broken rock mass is studied.2.Three kinds of excavation methods, such as ring - reserved core soil method, step method and full - section method, are used to study tunneling through fractured rock mass using theoretical analysis and numerical simulation method.The results show that the maximum horizontal displacements of the three methods are 11.97cm, 9.33cm and 37.20cm,respectively. It can be seen that the horizontal displacement of the step method is the smallest,which is close to the annular reservation core soil method. 30.92cm, 37.98cm, 59.94cm,respectively, while the maximum uplift was 23.67cm, 25.30cm and 31.68cm, respectively. It is obvious that the maximum settlement and uplift values of the ring-shaped reserve core soil method are the least, and the step method and the ring-reserved core soil method have advantages and disadvantages without considering the unfavorable effects such as gushing water. On the deformation of the surrounding rock, the annular reservation core soil method as a whole is slightly superior, but the step method construction progress is fast.3. When the intact rock-fragmentation interface gradually rises from the center of the tunnel to the right shoulder of the tunnel, the deformation of the whole tunnel and the deformation of the lining are more serious than that of the tunnel. Special damage characteristics.In the semi-intact-semi-fragmentation rock mass, the deformation of the tunnel is large, the large deformation area is near the fracture zone, and the intact rock mass is deformed by the crushing rock mass.4.The results show that the catastrophic mode of the tunnel in semi-complete-semi-fragmentation rock mass changes with the relative position of the interface, and the main failure rules are as follows:(1) Wedge extrusion damageDuring the process from the interface to the tunnel interface, the wedge shape is formed in the intact rock mass. The right side of the tunnel is crushed by the fractured rock mass,resulting in a gradual increase of the stress concentration in the wedge body. The rock mass is more prone to instability, resulting in the collapse of the overlying fractured rock mass. In this process, the lining structure is squeezed by the fractured rock mass, and it is prone to local cracking and even falling out, which may lead to destabilization of the tunnel.(2) wedge fracture tipThe wedge formed in the intact rock mass is the most "sharp" in the case of the tunnel profile and the approximate interface tangent, and is prone to fracture under the action of the crushed rock mass, resulting in the wedge body tip and the nearby fractured rock mass Collapse. This catastrophe model is the most unfavorable situation facing the tunnel, in the construction should pay close attention to scientific and rational means to strengthen.(3) Fracture of rock bridgeThe wedge formed in the intact rock mass is the most "sharp" in the case of the tunnel profile and the approximate interface tangent, and is prone to fracture under the action of the crushed rock mass, resulting in the wedge body tip and the nearby fractured rock mass Collapse. This catastrophe model is the most unfavorable situation facing the tunnel, in the construction should pay close attention to scientific and rational means to strengthen.5. According to the results of tunnel fragmentation stability analysis and the catastrophic characteristics and potential catastrophic modes of the surrounding rock of the fault zone tunnel, combined with the large deformation of tunnel surrounding rock and its construction survey data, and the long and irregular oblique fault, gushing water and broken surrounding rock Depth analysis of large-scale deformation of surrounding rock in complex geology, it is proposed to strengthen the tunnel by adding temporary support and combined with grouting small pipe to strengthen the support of additional tunneling and additional tunneling The control method and parameters of large deformation control of surrounding rock can effectively control the deformation of surrounding rock, which can provide a reliable reference for on-site construction.