Study On Consolidation And Permeability Of Quartz Sandstone Weathering Layer In Sijiaying

Located in the river basin of luan river,the sijiaying iron mine is affected by river alluviation.The quaternary aquifer is rich.The lower alluvium is weathering layer,which is relatively waterproof,making it a barrier between the quaternary aquifer and the underlying bedrock fissure aquifer.Due to underground mining,bedrock fracture water is released,pore water at the bottom of the weathering layer of quartz sandstone is basically in a state of no pressure,and the difference between the top and bottom of the weathering layer is increased.The effective stress changes.The study of compressibility permeability and seepage stability of weathering strata is guiding significance for the prevention and treatment of quaternary water resources and mine water.The regolith of quartz sandstone in Sijiaying area was surveyed in situ,and the undisturbed samples were taken from the regolith.The compressibility was evaluated by compression test,the compressibility index,compression modulus,early consolidation pressure and other parameters are calculated,and the compressibility influencing factors are analyzed.The permeability of weathered soil was analyzed and evaluated by conventional variable head permeability test,and seepage test and seepage deformation test of weathered soil after water release from bedrock cracks are simulated by self-made simulated soil column.The weathered soil of quartz sandstone belongs to silty sand,sand grain structure and medium compressibility soil,and its compressibility is greatly affected by its own sand grain structure,natural moisture content and porosity.The permeability of weathered quartz sandstone soil is similar to that of sandy soil.Simulated soil column infiltration experiments,weathered soil layer of gravel at the bottom of the hydrophobic early test result in weathered layer at the bottom of the interpretation of the water,the actual thickness of water-resisting layer decreases,and measured the permeability coefficient is higher than the saturated seepage,due to the weathering layer at the bottom of the interpretation of the water,the change of effective stress compressed soil weathering,late test,the state of unsaturated soils sample permeability coefficient is smaller than the permeability coefficient of saturated condition.The seepage deformation of weathered residual soil of quartz sandstone under a certain limit state has a critical hydraulic gradient of 74.6,and the maximum hydraulic gradient of weathered layer is less than 30 under the condition of "top off" of bedrock fissure water,which is not enough to cause seepage failure of weathered soil.Figure31;Table33;Reference 63.