Unloading Features Research Of Surrounding Rock For TBM Construction Of Deep Inclined Shaft With Abundant Water

Due to the reduction of shallow mineral reserves, the government pays more attention to deep mining, especially to the research of deep coal resources and mining. Along with the extension of coal mining in depth, we require higher techniques for inclined shaft mining. And compared with traditional construction method, TBM method boasts its features in safety, progress, quality and yields. It will be the inevitable leading trend for deep coal resources exploitation to introduce the technology of TBM in the construction of long inclined shaft. It will also be a revolution for coal mining technology in our country, being of great significance in social, economic, practical areas to the safety and efficiency of coal mining. TBM method is an innovative subject in coal mine construction field for deep inclined shaft with abundant water, which is featured by comprehensive and complex technology. In addition, due to the effect of unloading and groundwater seepage from excavation, it becomes more complex for the mechanical properties of surrounding rock during the TBM construction of inclined well. The Paper pays attention to solving the urgent mechanical problem of surrounding rock of the grotto for TBM deep well construction with rich water and great slope steepness. Based on the subject of national key research project development plan 973 “TBM rock breaking mechanism and evaluation methodology of excavation for deep compound stratum “(2014CB046903), it contains TBM inclined shaft project of a mining area as the background and main study object to study the unloading effect and mechanical characteristic of TBM inclined shaft surrounding rock stress under the impact of groundwater seepage. It takes the way by combining the tests, theories and numeric analysis as the research method. Its main research contents are as follows:① The paper confirms the mechanics parameters of TBM engineering research through mechanics test of the surrounding rock, and derive the rock unloading constitutive model by introducing damage variable based on Hoek Brown- criterion. At the same time, we take advantage of related information of Taige Temple TBM project,such as mechanical parameters of surrounding rock. Using the numerical software FLAC3 D and mathematical statistics software SPSS, we conduct the inverse analysis of unloading parameters to work out the variation rules between rock unloading rate and elastic modulus of surrounding rock.② First, this study uses the theory that the geometry size of the cavity will affect the gradient of the inclined shaft then infers the theory solution of the inclined shaft surrounding rock stress and displacement based on the complex function theory. Besides, this research have come up with another theory solution of the inclined shaft surrounding rock stress and displacement based on the polar coordinate system by converting the stress boundary conditions. Thus get the coefficient of deformation, stress and stress concentration coefficient of the cavity vault and haunch. Finally, this thesis has put the result of these two theory solutions onto the TMB inclined shaft project and compared it with the result of stress and displacement got by numeric analysis. It proves that the theory solutions are reasonable and this study also discusses the principle that the inclined shaft stress and displacement are various according to the gradient of the inclined shaft and the coefficient of lateral stress.③ Using the finite difference software FLAC3 D, we establish a numerical model of TBM construction to analyze unloading simulation method of excavation and the TBM construction process of dynamic simulation based on the unloading function and stress release function written by FISH language. And we also conduct a numerical analysis of both unloading and non-unloading conditions to study the displacement, stress and plastic field distribution by comparison the two conditions.④ Considering the groundwater seepage, the three-dimensional fluid-structure coupling numerical simulation research of inclined shaft TBM construction is performed based on the fluid-structure coupling numerical calculation theory. In addition, we study the influence of gradient in condition of rich water and analyze influence of seepage control factors(underground water level, porosity and permeability)on Contrast analysis of slope peace hole wall rock mechanical behavior characteristics, study the effect of water under the condition of slope, and respectively analyze seepage control factors(underground water level, porosity and permeability) of the changes on TBM surrounding rock deformation, stress, distribution of plastic zone and seepage field by comparative analysis of the mechanical behavior characteristics of inclined shaft and adit surrounding rock.⑤ The paper conducts the numerical analysis of the TBM dynamic construction of inclined shaft with abundant water considering the unloading effect and fluid-structure coupling effect, studying the evolution rule of surrounding rock deformation, mechanical stress, plastic zone, unloading zone as well as seepage field distribution along with the construction progress. We also conduct the research of influence of lateral pressure coefficient, slope gradient, cavity diameter, grouting time, supporting stress ratio of the excavation side on the stability of surrounding rock. Based on the analysis of these factors, we work out the dynamic and static rule of TBM evacuation covering displacement of surrounding rock, mechanical stress and plastic stress distribution and unloading distribution. Along with the research result of influence factors of surrounding rock stability, we carry on optimization study on conventional control measures for TBM excavation rate, segment supporting time and bolting deformation.⑥ Conduct the secondary development of FLAC3 D taking VB.NET as the platform. And combine the two-dimensional computation theory of inclined well to integrate the three-dimensional numerical simulation and theoretical calculation, establishing the surrounding rock stability analysis software integration system of TBM excavation. In addition, it gives an simple instruction to the system as well as the engineering case application.