Research On Surrounding Rock Stability And Supporting Of TBM Excavated Coal Mine Roadway In Deep Strata

Tunnel boring machine (TBM) had been widely used in various fileds like traffic, Hydraulicien, urban railroad transportation and etc, accompany with emerging of relative theories and key technologies. Due to the complex ground condition of shaft coal mines, the practices and researches of applying TBM at shaft coal mines barely been conducted both in China and abroad. The paper conducted researches on surrounding rock stability and supporting technology of TBM excavated roadway at shaft coal mines. The research results have theoretical significance and practical value to excavating shaft coal mine roadway in deep rock strata safely, rapidly and efficiently and promoting technological revolution on roadway driving at shaft coal mines.The paper takes the 1413A methane drainage bleeder at Zhangji coal mine as study case, and studied key technological issues on roadway surrounding rock stability of hard rock strata in coal-bearing formations according to the ground characteristics such as thick overburden of roadway, complex ground stress distribution, uneven distribution of fracture development and high penetration rate. Through uniaxial compress testing, triaxial compressive testing and triaxial cyclic loading and unloading testings, mechanical behavior of quartz sandstone had been studied, which are:peak strength is related to confine stress and stress path, the rock specimen got higher peak strength under higher confine stress and the strength of rock specimen; in cyclic loading and unloading test is lower than that in triaxial compressive testing due to accumulated damage; the microscomic fracture development causes brittle failure of sandstone.In this paper, testing data of triaxial cyclic loading and unloading test had been fitted by multi linetype. Conducted statistical method, chose the best strength envelop which is power function Mohr strength envelope by comparing determination coefficient. Strength principle and constitutive model were also established on base of power function strength envelope. On the base of analytical mechanical solution of circular roadway, elastic and plastic analytical solution of circular roadway under asymmetry ground stress field had been developed by perturbation method. The solution raised accuracy of calculation and a calculation example was made. The calculation results indicated that the stress magnitude have a more significant on plastic zone range than support stress level. Shape of plastic zone is mainly influenced by lateral pressure coefficient.On the base of results of triaxial cyclic loading and unloading test, customized development of FLAC3D had been conducted. Power function Mohr model had been established, and takes advantage of it, development of stress field, displacement field and plastic zone had been studied. Moreover, compared results of customized and Mohr model, the conclusion is:the stresses filed of roadway surrounding rock calculated by two models are similar. However, customized model generated larger plastic zone and displacement which are closer to in-situ measurement value.Conducted large scale in-situ test:drilled a couple of boreholes around the roadway for installing optical fiber, electrical resistance sensors and acoustic CT devices; got distribution of stress filed, geoelectic filed and acoustic velocity filed. Time-space effect of the influence of TBM excavation to surrounding rock disturbance and stress filed and displacement filed development is also been studied. Measurement data also been used as basis of supporting design feasibility.According to features of TBM excavated rock roadway, the paper deeply analyzed applicability of various supporting patterns, studied mechanics characteristic of supporting structures during TBM excavating period and optimized design parameters base on computer simulation results. In-situ monitoring indicates that:surrounding rock is stable, the supporting pattern is chosen due to low cost, convenient and fast construction.Through above-mentioned researches, technology system of TBM excavated hard rock roadway stability and supporting theory had been established. The research works were conducted at the same time of design and construction of TBM excavated roadway, therefore, research of this paper had played a significant role in feasibility study and supporting design. Moreover, the research result, along with construction experience, were accepted and applied in later similar projects.