Detection Of Structure In Deep Coal Mine And Study On Random Aperture Grouting Model In Fracture

The dissertation, aiming at serving coal mine production safety and toward the goal of prevention of the Ocdovician water inrush from deep mine floor, closely focuses on the pivotal keys of exploration and prevention. From the application of composite geophysical prospecting in detecting blind aquifer structure, the ratio test of grouting material and its percolation law in fractured rock are deeply studied and explored in this dissertation. The following is the main research contents and results.(1) In accordance with the existing hydrogeological data and based on the dynamic and kinematic principles of seismic wave, three-dimensional seismic prospecting is carried out on the ground in large area. With the preliminary earthquake field test, the reasonable layout of data acquisition system is confirmed. Subsequently, through a series of seismic corrections and by analyses of time profile, bedding and horizontal slices, the occurrence and spatial distribution of fault structures are ultimately proved up and explained.(2) In contact with three dimensional seismic prospecting results on the interpretation of fault water channel, the transient electromagnetic method, grounded on the secondary scattering principle of low resistivity to high frequency electromagnetic field, is developed for detecting abnormal rich water area within 80m range of roadway floor. According to local conditions, the coplanar dipole loop device is selected. It is found that the hydraulic connection between small fault and deep low resistivity body have greatly influence on the response curve, the slop of which make a greater flexure. Furthermore, the apparent resistivity value is stable and reliable by utilizing the calculation of Bz. Finally, based on the time-depth conversion model and inversion performance, the section maps and horizontal slices of apparent resistivity of floor are accomplished, which further verified the abnormal water rich area.(3) The analysis and study, in regard to consistency, stone rate, bleeding, uniaxial compressive strength and other physical mechanical properties for different ratios of cement slurry, cement-sodium silicate slurry, cement-fly ash slurry and fine cement slurry, are implemented with the consideration of different amount of water reducer. From experimental study, it is shown that the bleeding of cement-sodium silicate slurry is lower than single cement slurry and well stability than it. Cement-fly ash slurry holds the low bleeding and good fluidity, which achieves the best performance ratio in the case that the water-cement ratio is 0.8, the mass of fly ash is 40% to 45% and the amount of water reducer is not more than 1.0%. Furthermore, the fluidity of fine cement slurry has the significant improvement with the increase of water reducer, and that its strength also develops obvious enhancement in conjunction with the increase of water reducer and the decrease of water-cement ratio. Finally, the results of the cementation test between different slurries and coal blocks demonstrat that the strength of mechanical vibration is higher than that of manual vibration under certain conditions, but for fine cement the strength is not very distinct.(4) On the ground of three-dimensional constitutive model of Binghamian materials and incompressible viscous Navier-Stokes simultaneous equations, the Bingham flow equation is derived and its flow discharge formula is also given in a two-dimensional smooth and inclined single fracture. Based on the fractal theory of multifractional Brownian motion, four groups of fracture surfaces of different regularization dimensions are constructed, and then, the corresponding random apertures are obtained by the transform of height function data, all of which more realistically reflects the asymptotic self-similarity of aperture distribution of natural fracture surface.(5) From the numerical simulation of Binghamian material percolation in a single random aperture fracture, it is presented that pressure contours show twists and turns spreading over time, which reflects the distinct anisotropic characteristic. The distribution of closed area has a tendency that is from dot-like scatter to focused plane with the regularization dimensions tending to reduce, and its spatial location has obvious influence on the pressure and grouting time. As the development of percolation, there appears a tend that the node pressure is from monotonically rapid increase to stepwise stable, and the more the node approaching the percolation border, the shorter the grouting time used in the case of reaching to steady pressure. Moreover, there has a power relationship between the node pressure and grouting time. In view of this rule, empirical equations of different parameters are also obtained by curves fitting.(6) Based on the equivalent continuous medium grouting theory, the finite element method is used to simulate cement-sodium silicate slurry multi-drilling holes grouting in the intensive fractures sandstone of roof at a new sump of the East one drift, which reflects the law of isotropic permeability.