Dynamic Response Analysis Of The Tunnel Through Fault Zone And Its Optimization For Grouting Scheme Under Blasting Excavation

With the large-scale construction of tunnel engineering in our country, it is often seen that the tunnel crosses the poor and complex geological, such as the fault zone. Subjected to the blasting load, the blasting vibration effect of surrounding rock will be inevitably generated with varying degrees of damage and failure. Moreover, the characteristic of large deformation and strong vibration, which seriously affects the schedule and the safety under the tunnel construction, will be produced in the fault rocks. Therefore, the study on the construction mechanical behavior of tunnel rock affected by fault zone during excavation with blasting method has become one of the hottest issues in tunnel engineering. To analyze the above subject, the Kuiba Road Tunnel is taken as engineering background in this paper. Then, a research project, which is related to the impact of the tunnel crosses fault zone under blasting excavation and the optimization scheme of grouting, is systematically analyzed on the basis of existing research results.First of all, the formation mechanism of fault zone and its influence on stability of the tunnel site under construction were analyzed. And on this basis, a brief overview of the control principle of rock blasting was introduced. Therefore, it provides a theoretical basis for the dynamic response analysis of the tunnel through fault zone under blasting excavation.And then, based on the theory related to blasting and engineering experience, the blasting scheme was designed. By comparing with the theoretical assembly dose, it was verified that the design scheme of blasting was reasonable. In order to simulate the effect of blasting loads, according to semi-theoretical and semi-empirical formula, a function of blasting load could be constructed by constantly revised to meet the basic characteristics of shock wave, and eventually was added to the finite element model.In this paper, a three-dimensional numerical simulation for a tunnel crosses fault zone under blasting excavation process was conducted by means of the finite element software ANSYS/LS-DYNA. The influence of different fault dips and locations on the dynamic mechanical response of the surrounding rock was analyzed, and the most unfavorable position and working condition of the fault tunnel under blasting construction were put forward. Furthermore, the influence area of blasting vibration could be obtained. And also, a safe distance between the side wall of tunnel and the fault zone was made suggestions. In short, these conclusions could provide the basis for the study of the fault tunnel stability, and provide reference for the design and safety construction of similar project in future.Owing to the mechanical properties of fault rock in Kuiba Road Tunnel, different grouting reinforcement schemes were put forward to obtain the optimal grouting scope to meet the requirement of engineering construction. By the means of comparing the numerical simulation results, it was verified that pre-grouting treatment could effectively control the dynamic response distribution of the tunnel affected by fault zone, and was provided reference for the optimization design of grouting scheme of similar project.This thesis is on the forefront of academic research. Using advanced numerical methods and analytical means, the study for the dynamic response characteristics of the tunnel affected by fault zone and the optimal grouting scheme was carried out. The work done has a high engineering application value, and provides an effective means to systematically analyze the influence of tunnel with the fault zone during the period of blasting excavation.