Duration Stability And Control Technology Of Deep Shaft Ingate In Coal Mine

Coal mines have characteristics such as complex geological conditions, large ground pressure and others in deep strata. Because deep shaft connected chambers located at the throat of mine system, large section of chambers is designed and rock was repeatedly disturbed in construction process, deep shaft connected chambers damage occurred, the stability of surrounding rock was seriously affected and the supporting structure safety was decreased. In response to these technical problems, to ensure that the shaft connected chambers stability and security of supporting structure, we use study methods such as theoretical analysis, model test and field measurement. Deep shaft connected chambers rock disturbances mechanism, methods of design, control technology and construction techniques were scientific researched. The main research work and achievements in dissertation is as follows:(1) Triaxial creep test about sandy mudstone in deep formation was done at laborary, variable parameter nonlinear viscoelasto plastic burgers creep constitutive model was established that based on the linear burgers model. It can completely describe creep mechanical behavior of sandy mudstone at low stress level and high stress level while specimen was ruptured. Using the Marquardt algorithm the creep parameters of the model was identified. It can be found that the axial and radial strain parameters about the creep model were different to sandy mudstone under the same stress level. That sandy mudstone had the characteristics of anisotropy creep model parameters should be considered while secondary development of constitutive model in numerical calculation was carried out.(2) Huainan certain mine auxiliary shaft ingate used as the prototype, large three-dimensional numerical model was established. Combined with variable parameter nonlinear creep burgers model in rock creep test of deep stratum, secondary development of user constitutive model in numerical calculation was carried out based on ABAQUS. It was used in three dimensional numerical simulation analysis about deep shaft ingate rock mass duration stability. Numerical computations revealed distribution rule of the ingate rock mass displacement field and stress field and the supporting structure mechanics characteristics. It pointed out that with the time elapsed and staged excavation of ingate, the main stress concentration area shows "duration three zone converting" rules. A set of large deep shaft ingate complete duration numerical analysis methods was established, which can assess the stability of ingate rock mass. The results of numerical analysis were the basis of ingate rock mass deformation control technology and support optimization design.(3) Large three-dimensional physical model test device to deep coal mine shaft ingate was developed. Combined testing system including optical, electrical and electric resistance type sensor was used for the first time. Stress field, displacement field and the loose range variation laws had been got during deep shaft ingate excavation process. The fiber sensor test revealed that the shaft and ingate junction rock mass was significantly influenced by shaft and ingate excavation. The affected range is approximately 300mm, influence range equivalent to in practical engineering is 15m; affected range on both sides of ingate rock mass is about 200mm, influence range equivalent to in practical engineering is 10m. Caused by excavation, the shaft and ingate rock mass stress reduction. Above ingate roof 2 or 3m, rock mass stress drop from the original to 20 or 30 percent. Electrical test system measuring the thickness of the loosen zone is about 200mm-300mm, it uniform to the optical fiber testing results.(4) Numerical calculation and model test revealed the rock mass stability with time evolution of deep shaft ingate. Combined with monitoring results of engineering application, based on the geological condition, the deep shaft ingate construction process and the design of supporting structure, series control technology about the deep shaft ingate rock mass deformation were put forward. From the aspects of charge structure, blasting parameters and the surrounding control blasting technology to realize the control of blasting on the disturbance of rock mass. Between the chamber of underground ingate and two sides of the subsequent tunnel construction was a row of dense deep drilling. It can reduce the disturbance on supporting ingate lining and rock mass from adjacent chamber construction and deformation. Two sides of ingate lining concrete poured at one time. The length is lengthened from 3m to 6 or 8m. Including upper and lower shaft lining, the signal of chamber and a hydraulic pump station and other chamber supporting structure constructed at the same time. It can avoid the subsequent construction disturbance on shaft which was existed before. Classification strategy is proposed to connect shaft lining and ingate chamber supporting structure considering depth, deep vertical shaft ingate main lithology and section size and other factors.(5) The rock mass control technology is successfully applied to some pairs of deep shaft ingate project in Huainan and Huaibei mining. Reinforced steel stress and concrete strain of support structure and section convergence curves variated gradually slow to ingate after 100 days. Ingate rock mass and retaining structure interacted effectively. Chamber deformation was effectively controlled. Deformation can be easily accelerated caused by construction of other chambers near the deep shaft ingae. It will cause serious structural damage sometimes, so real-time monitoring of the internal ingate structure and surface convergence is needed. Wall back grouting and anchor lining structure would be used when necessary to ensure the stability of the deep shaft ingate.With the mining depth increase gradually about coal resources at home and abroad, the application of deep shaft ingate rock mass control technology will be paid more attention and promoted.