Macroscopic And Microscopic Mechanical Parameter Calibration Study Of Fractured Surrounding Rock In Cavern

With the economic development of socity, the development and utilization of underground resources and underground space is becoming more frequent. At the same time,the depth and extent of development is increasing. Types of underground engineering are inevitably encounter the stability problems of fissured surrounding rocks. Fissured surrounding rock is a special particle aggrcgate.It is a type of intermittent media between the continuous medium and granular media Its special particle spatial structure makes its engineering properties show strong nonlinearity, spatial variability, environment dependent, time variability and heterogeneity. Current research is generally from experiments constitutive relationship and numerical calculation.This article shows the analysis of several problems on studies of fractured surrounding rock engineering properties from the perspective of numerical experiments.VWe selected UDEC as numerical analysis software platform. Relying the reborn temple retrofit engineering of Mountain Jiuhua in Nanjing, we launched on the macroscopic and microscopic mechanical parameter calibration studies of fissured surrounding rock. The following results was achieved:We expounded the history studies and current situation in terms of fractured surrounding rock at home and abroad, including describing the theoretical research from classical mechanics to the modern process of fracture damage mechanics, analysing of the various theoretical and numerical simulation methods in a simulated fractured rock mass stress and crack propagation aspects of the advantages and disadvantages,and summarizing on the crack propagation test results and methods of fractured surrounding rock in recent years.Use based on the theory of particle flow numerical model was established UDEC software and test results were compared, the results are similar between the two. Verified UDEC software as a mesoscopic simulation method in fractured rock macro-micro simulation parameter calibration have a greater advantage.Microscopic parameters and macroscopic parameters is not a simple relationship between the sum is part of the whole and the dialectical relationship. Overall mechanical behavior beyond the part of the mechanical behavior, with a significant enhancement and amplification, a variety of factors which both independent and related. Where the coefficient of friction, contact radius multiplier, the elastic modulus of the material mechanical behavior is comprehensive and elastic modulus increases, will cause an increase in the number of cracks, sharp reduction in energy intensity is not changed regularly. Contact radius multiplier increase will make the material strength and deformation properties are improved, and energy were increased crack. Increase in the coefficient of friction will cause the increase of strength and deformation properties, cracks, and little change in energy, but the friction can increase significantly. Micro strength of relatively independent, causing only increase the strength of the macro, has no effect on the deformation.UDEC software and 3DEC-Voronoi microscopic parameters, which are relatively complicated work, often can get twice the result with half the effort based on known some regularity understanding. In general, the numerical test can follow these recommendations: ①The block deformation parameters can be reference laboratory sample results or define GSI as the upper limit of surrounding rockmass which is obtained by Hoek-Brown parameter system, and because of of size effect, the latter is much better, such as in the wall rock or category Ⅲ, the block GSI=60; ②In the process of debugging the macro deformation parameters of specimen, block and structural surface adopt elastic model, and the fixed block parameters is constant, just the structure stiffness condition changes. The stiffness of structural surface is proportional with the macroscopic elastic modulus, stiffness ratio Kp/Ks and Poisson’s ratio also is proportional; ③The lower residual strength of structure surface means brittle characteristics of strengthening rock specimen.