| When a deep and long tunnel in complicated difficult mountainous area passes through a fault fracture zone,the tunnel construction will affect the stability of the tunnel surrounding rock,and the phenomenon of loose deformation,collapse,water inrush,etc.of the formation may easily occur,which may cause the tunnel to be unstable and even affect on the surface buildings,with some disasters,such as large deformation of structures.At present,the construction technology of large and deep long tunnels that safely and quickly traverses the strata in complicated difficult mountainous areas of faults and fractures is not yet mature.Therefore,in order to make the tunnel pass through complex strata safely and quickly,it is of great practical significance to carry out research on the geological hazards problems that are prone to occur when the tunnel passes through the fault fractured zone of the complicated mountainous areas.In view of the above problems,this paper takes the Emeishan-Hanyuan Expressway Shuangqiao Village Tunnel as the engineering support of the thesis,and takes the large buried deep tunnel through the fault fractured zone as the research obj ect.First,the law of change of the rocks surrounding tunnel,reasonable selection of excavation methods,and optimization of construction parameters are analyzed when the large buried deep tunnel in the complicated mountainous area passes through the fault fractured zone,and then targeted stratum grouting reinforcement measures are put forward.At the same time,a comparative analysis with the actual monitoring data of the tunnel through the fault fractured zone is made.The main research work of this article is as follows:(1)In this paper,the basic theories and equations such as the strength criterion are first studied,and then this paper is based on the geological structure and stratigraphic parameters of the Shuangqiao Village Tunnel.The FLAC3D software is used to establish a numerical model for calculation.And this paper simulates different excavation methods to pass through the fault fracture zone.Some analysises that different excavation methods such as the full-face method,the upper and lower steps method and the reserved core soil method have influences on plastic zone,displacement field and stress field of the surrounding rock when the deep and long tunnels pass through the fault fractured zone in complicated difficult mountainous areas.Reveal the impact of different construction methods on the surrounding rock of the tunnel.(2)This paper is based on the selected excavation methods,using numerical simulation software to optimize different excavation footage,The comparative analysis of the variation laws of the plastic zone,displacement field and stress field of the surrounding rock of the tunnel under different excavation footage reveals that the impact of excavation footage on the stability of the tunnel during excavation construction.The results of the study show that the excavation footage is not as small as possible.There is a reasonable excavation method for the excavation method.Excavation footage is too small,but the growing number of disturbances will increase the influence of tunnel excavation on the surrounding rock,and the necessity of advance grouting reinforcement of the surrounding rock of the tunnel vault is obtained based on the numerical simulation calculation results.(3)According to the evaluation of the impact on the tunnel construction,aiming at the development of the plastic zone of the surrounding rock of the tunnel vault and excessive deformation when the tunnel passes through the fault fractured zone,a targeted advance grouting reinforcement design is proposed,which is compared with the measured monitoring data.The comparative analysis verifies the feasibility and accuracy of the numerical simulation,and the monitoring data proves that the design effect of the advance grouting reinforcement of the tunnel vault is significant,which can effectively ensure the safety and rapid construction of the tunnel. |
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