Multi-scale Simulation Study On The Progressive Failure Mechanism Of Tunnel Surrounding Rock Mass Containing Weak Interlayer

The collapse of tunnel surrounding rock is the most common disaster in the process of tunnel construction,which not only causes the interruption of tunnel construction and operation,but also leads to the loss of life and property.A large number of tunnel engineering practice shows that the soft interlayer has a decisive influence on the stability of tunnel surrounding rock and construction safety.Therefore,it is very important to study the collapse mechanism of tunnel surrounding rock with weak interlayer for tunnel design and construction.Many researchers have done a lot of research,but the research is not comprehensive and in-depth.The most common grade of highway tunnel(with weak interlayer),V(mean)of surrounding rock as research object,simulation of the mechanism with weak interlayer tunnel progressive collapse of the multi-scale simulation study using experimental and numerical model of the tunnel,the research contents and results are as follows:(1)Analysis of the causes of a large number of highway tunnel collapse accident,the influence of soft interlayer on the stability of tunnel surrounding rock is large,and the research status is summarized;(2)According to the continuum and non continuum calculation principle and their respective advantages,this paper presents a simulation method of multiscale continuum and non continuum coupling based on FLAC and PFC program as a platform,using the method of multiscale numerical simulation analysis of the tongluoshan tunnel,through the Kirsch formula to verify the accuracy of the method and the rationality,and analysis of the damage area and the displacement of tunnel surrounding rock,the range of non continuum model derived coupling;(3)The V-grade(mean)rock highway tunnel as the research object,the preparation of similar material with a variety of rock material,the development of the physical model test system of tunnel surrounding rock,this paper presents a test system combined with non-contact full field strain measurement technique and pressure sensors,and use it to carry out the destruction of the surrounding rock of the tunnel test study the V-grade surrounding rock during the tunnel excavation of the progressive failure pattern and mechanism;(4)According to the similarity ratio of the model test,the similar material of thefourth grade rock and weak interlayer is prepared.Based on the test system,the progressive failure mode and mechanism of tunnel surrounding rock with weak interlayer are studied;(5)The IV(with weak interlayer),V(mean)tunnel model test as the background,using FLAC-PFC multi scale numerical simulation of two-dimensional,obtains the variation law of surrounding rock in shape,displacement and damage area,the results and the model test of tunnel is roughly the same,a comprehensive analysis of tunnel surrounding rock with weak interlayer progressive mechanical characteristics and morphology destruction,and gives the design and construction of tunnel with weak interlayer method is suggested.