| With the acceleration of urbanization and infrastructure construction,the demand for cement has increased sharply.As the main raw material of cement production,the demand for limestone has also increased synchronously.However,frequent unreasonable mining activities have destroyed the ecological environment around the mine,sinkhole has become the main geological environment problem faced by mine construction.At present,the research on mine environmental problems mainly focuses on soil erosion and landslide,while the research on sinkhole induced by limestone quarrying is less.With the expansion of quarry mining scale,the prevention and remediation problems of mine-type sinkhole need to be solved urgently,such as the distribution law of karst development in mining area and the main flow path of groundwater,the variation characteristics of groundwater dynamic field during quarrying operation and the prevention and remediation measures of mine-type sinkhole.In this paper,Shangwo quarry in Longmen County,Huizhou City was taken as an example to carry out a comprehensive study on the prevention and remediation of sinkhole disasters in mining areas.Through the research on sinkhole development characteristics,karst detection technology,groundwater dynamic field characteristics,evaluation of sinkhole susceptibility,and sinkhole prevention and remediation measures,a mine-type sinkhole prevention and remediation system was established,which had important guiding significance for the prevention and remediation of sinkhole disasters induced by limestone quarrying.The main achievements of this paper are as follows:Study on sinkhole development characteristics.Through field investigation and data collection,it was analyzed that the main factors of sinkhole development in the study area are karst development degree,Quaternary overburden thickness and structure,quarry drainage,artificial pumping of groundwater and surface water infiltration.The formation mechanism of sinkhole in the study area was analyzed according to the development and distribution law of sinkholes.According to the seepage deformation test,the critical wave velocity of groundwater in the study area is 2.23?4.70 cm/min.The critical wave velocity of groundwater can be used as a criterion for the stability of soil under latent erosion.Study on karst detection technology in mining area.High-density resistivity method,transient electromagnetic method,controlled source audio-frequency magnetotelluric method and wide area electromagnetic method were used to detect the deep structure and development and distribution characteristics of karst around the mining area.Combined with drilling validation,the detection effects of different geophysical methods of practical work were compared,and the detection method suitable for the distribution characteristics of fault structure and karst development in mining area was proposed.The high-density resistivity method has high resolution of detecting shallow karst development area,and the interpretation results basically reflect the law of shallow karst development in the detection area.Wide area electromagnetic method has the advantages of large detection depth,high working efficiency and strong anti-interference ability,which can truly to reflect the change of resistivity of underground rock mass,and has good applicability to the detection of deep structure of mining area.When there is a large area of surface water in the detection area,transient electromagnetic method becomes the preferred method for deep structure detection.Study on characteristics of groundwater dynamic field.Based on the analysis of sinkhole mechanism and the seepage deformation test of undisturbed soil samples,it was pointed out that the change of groundwater-air pressure in karst pipeline system is the main driving force for inducing sinkhole.The monitoring and prediction system of karst groundwater-air pressure was established to grasp the variation characteristics of regional groundwater-air pressure in real time,which is used to analyze the formation mechanism of sinkhole and guide the safe mining of the quarry.Visual Modflow software was used to predict the change of groundwater dynamic field,and the change characteristics of groundwater dynamic field under different mining depths were analyzed,which provided support for the optimization of mine construction and sinkhole prevention scheme and the reduction of the risk of sinkhole.Study on susceptibility evaluation of sinkhole.Nine influencing factors of sinkhole,including karst development degree,rock mass structure characteristics,fault location,soil thickness and structure,annual variation amplitude of groundwater level,position of groundwater from rock surface,fluctuation speed of groundwater level and artificial drainage intensity,were selected as the analysis factors.The analytic hierarchy process(AHP)was used to evaluate the susceptibility of sinkhole.The study area was divided into high,medium and low levels.The high susceptibility area was 4.72 km~2,that of medium susceptibility was0.22 km~2,that of low susceptibility was 0.19 km~2,and that of bare karst was 0.85 km~2.The evaluation results of zoning have a good corresponding relationship with the distribution of sinkhole,and the evaluation results are in line with the actual situation.Study on prevention and remediation of mine-type sinkhole.The prevention and remediation system of mine-type sinkhole was established based on the principle of“external interception and internal plugging”,combined with the monitoring and prediction system of karst groundwater-air pressure and grouting curtain technology,and grouting effect of the curtain was evaluated by comprehensive detection methods(high density resistivity method,verification drilling,water pressure test and groundwater level dynamic monitoring). |
PDF Full Text Request