| The groundwater flow and solute transport in rock mass is influenced by the fault structure and structure fracture that are formed under the tectonic movement.The distribution of structural fracture caused that rock mass shows strong heterogeneity,while the development and characteristics of large fault tectonic significant impact on the groundwater flow and solute transport.In this paper,taking 3720m of the first mining region of Pulang copper mine as an example survey the filed then arrange and analyze the date in room.Generalise the development and distribution regularity of fault tectonic and structure fracture in the rasearched region and calculate the average permeability coefficient of bedrock using the date that obtained by hydrogeological drill pumping test.We combine the characteristics of structure distribution and average permeability coefficient of the bedrock,use HYDROGEN program to generate the inhomogeneous seepage coefficient field in the study area,use the program MODFLOW to simulate the groundwater flow field in the study area.we analyze the situation caused by structural fracture in heterogeneous rock mass and fault structure,use MT3DMS software to simulate the migration of pollution plume in different locations in the study area.In the condition of other modeling settings data unchanged,We change the water transfer characteristics of some fault structures in the study area,that is to say,to change the permeability coefficient of fault structure.We simulate and analyze the characteristics of groundwater flow and solute transport in a heterogeneous rock mass near the fault structure and the variation of fault structure.Through the research and analysis,the following conclusions are obtained:(1)Faults and tectonic fissures of the rock mass affected by tectonic stress are developed in the study area.And only Heishuitang fracture is water-conducted fault,for the rest of the large fault structures are water-blocked faults.The trend of tectonic fractures is mainly from the northeast to the northwest,and the rock mass shows strong heterogeneity.The main direction of permeability coefficient is consistent with the trend of the tectonic fracture.(2)There is a tendency that the underground water flow is concentrated to the strong permeable aquifer in the heterogeneous rock mass formed by the development of structural fractures.Along the flow direction,the flow evacuates at the front end of the weakly permeable rock mass,while concentrate at the rear end of it.The fault structures,as water-blocked faults,obstruct the groundwater flow along the main direction of water flow.Near the water-blocked faults,the water head lines are dense.Water-conducted faults are favorable for the flowing of the groundwater.(3)The potential pollution sources migrate along the direction of water flow,whether in the faults or in the goaves.The water-blocked fault has a delayed effect for the solute migration,and the solute diffusion is slower in the flow direction.Relative to permeable stratum,plume diffusion range increases in vertical flow direction.In front of the contaminant plumes,trailing phenomenon is obvious.In water-conducted fault the solute migrate rapidly.Along the flow direction,the solute can migrate a long distance.(4)The water-conducted fault formed the dominant flow channel.When the solute reaches the dominant flow channel,it passes through the relatively strong permeable layer quickly.In the dominant flow channel,the water flow is large,the dilution effect is strong and the peak concentration of solute is relatively low.A relatively weak permeable layer is formed by the water-blocked faults.After entering into the weak permeable layer,the solute will take a the long time to passes through the weak permeable layer.Moreover,there is less water in the crevice,and the dilution effect is weak,so the peak concentration of solute in the weak permeable layer is relatively large.The weak permeable layer has a cumulative effect on solute. |
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