Study On Controlling The Surrounding Rock Deformation Of Tunnel By Long Bolt

Study on controlling the surrounding rock deformation of tunnel by long bolt and controlling the deformation by numerical simulation has real values in engineering applications. The main purpose of anchor settings and other reinforcement methods is to strengthen the weak levels of sheer rock performance, delay or inhibit the dislocation between layers to improve the structure stability and security. However, there are still three questions in support engineering processes:First, if the supporting structure of the safety factor is too large, will resulting in waste of resources and the money; Second, if the supporting structure of the safety factor is too small, would not achieve good supporting effect and security; Third, lack of relevant research data and no law to provide reference for technical support increasing the difficulties in support engineering process. Thus, the study of this paper is important.This paper described in detail both in anchorage design method and the finite element method, based on that, designed comparison of the condition controlling by long bolt and described the process facilities of long bolt in detail. Also discussed the selection of the mechanical model in tunnel support simulation, use the large general-purpose finite element analysis software ANSYS to simulation of the deformation in controlling the surrounding rock deformation of tunnel by long bolt.This method is based on rock mechanics, analysis the internal force and deformation by surrounding rock-structure model, and can obtain the stress state of rock after excavation and the deformation hole surrounding and the bolt axial force, which can determine the parameters of bolting choice is reasonable and the rock excavation in the tunnel is stable, and ensure the tunnel and underground construction are safety. This paper established the vertical section of the tunnel model based on the actual engineering project survey, simulates and analysis the bolt length. Three conditions of simulation results were compared, there bolt lengths are 4m,6m and 8m.Numerical simulation the three conditions by ANSYS, maximum deformation of the vault controlling by 274m bolts is 28.02cm, maximum deformation of the vault controlling by 276m bolts is 24cm, maximum deformation of the vault controlling by 188m bolts is 18.33cm, controlling by 18.8m bolt is the most effective method; simulation also shown, when the bolts are arrangement horizontally, some bolt's axial force variation of a single peak. Meanwhile, at different levels of depth and rock, simulating the effect of the supporting of three conditions, and the supporting effect of 8m bolt is better than the supporting effect of 4m and 6m anchor bolt.Through theoretical research and comparative analysis of simulation data, arrangement the bolt for the specific terrain and mechanical properties of surrounding rock, for soft rock tunnel reinforcement, long bolt is better than the ordinary bolt, and the reference data for the actual support engineering and further research in future is valuable for practical engineering applications.