Hydrodynamic Characteristics Of Porous And Water-Enriched Sandstone Aquifer During Disturbed Process

Water hazards usually are serious when vertical shaft construction and underground miningreveal mesozoic porous and water-enriched sandstone which widely distributed in westernmining area in China. Water hazards management becomes a key technical challenges becausethe hazards increase project costs, delay the construction period and affect production. Aimed atthe prevention and control of water hazards challenges in vertical shaft construction, by theoryanalysis, experimental in the lab, numerical modeling calculation, this thesis deeply studies thehydrodynamic characteristics of porous and water-enriched sandstone aquifer during disturbedprocess. The following results are obtained.This thesis are studied the seepage characteristics of different viscosity fluid (groundwaterand chemical grout) under the natural state using the method of natural electric field and artificialelectric field combining by water injection and the grouting test of weakly consolidatedsandstone model. The water level rise height and flow velocity under the condition of the test areattained according to primary field potential and exciting current. The natural potential lineardecrease with increase of model unsaturated thickness as the water injection according to theresponse of natural potential. The natural potential began to fall and exciting current jumpindicates that the chemical grout seepage reach monitoring point, chemical grout filling effect isjudged by changes in apparent resistivity. The average diffusion speed and radius increasedapproximately by the square root with the permeability coefficient in different permeabilitymedia under the same conditions.The correlativity of mechanical properties and anti-permeability of porous sandstone isdiscussesed, the expression of ratio of critical anti-permeability strength and peak strength isproposed, based on characteristics of permeability evolution and its coupling with stress andstrain before peak pressure during complete stress-strain path. The relational expression ofpermeability coefficient and the volume strain in pore seepage phase in damage process isestablished on the basis of Kozeny-Carman formula and mass conservation equation of porousmedia. The relationship between permeability coefficient and the volume strain is described bydouble porosity/dual permeability model in the plastic deformation stage which fracture seepageis mainly.Hydrodynamic field response law of porous sandstone aquifer during vertical shaftexcavation by physical simulation experiment and numerical modeling analysis is that thehydraulic pressure isobaric surface is a horizontal plane in the beginning, afterwards, becomes toreverse cone-shape and reverse truncated-cone with the increase of excavation depth under single seepage conditions. The law of hydraulic pressure drop changes with excavation depth anddistance from the center of the well is obtained. There is a phenomenon that the aquifer havehorizontal, vertical and three dimensional seepage area in excavation. The change rule of waterinflow, and the relationship between water inflow and permeability coefficient, excavation radius,hydraulic pressure drop in vertical shaft bottom, thickness of the aquifer, model length arein-depth researched. The fluid-mechanical interaction module in FLAC3D with changeablepermeability coefficient is adopted to simulate the seepage field-strain field of sandstone aquiferin vertical shaft excavation, and variation characteristics of permeability of surrounding rock isgained. Hydraulic pressure distribution in aquifer and vertical shaft water inflow change ruleunder considering and not considering fluid-mechanical coupling effect at different excavationdepth are comparative studied.The calculate formula of vertical shaft water inflow is established by multivariate nonlinearfitting analysis based on the results of numerical calculation. The water inflow expected value ofmain shaft, auxiliary shaft and air shaft of Wen jiapo coalmine using the established formula ismore in line with and closer to the the the actual value compared with the calculated value byunder pressure-without the pressure formula.