中国岩溶2023，Vol.42Issue(6)：1331-1338,8.DOI:10.11932/karst20230615
基于高密度电法的城市岩溶地下水通道三维电性成像
Three-dimensional electrical imaging of urban karst groundwater channels based on electrical resistivity tomography
摘要
Abstract
In China,approximately 346.3×104 km2 of the karst rocks are distributed,accounting for about one-third of the country's land area.Karst groundwater channels are common geological phenomena in concealed karst areas.Various karst caves and underground channels widely developed cause the complex groundwater system dominated by pipe flow,which promotes the transport of groundwater,soil,and rocks,resulting in complex geological issues for urban underground space development and utilization in karst areas.In these areas,ground collapse disasters occur from time to time.In geothermal areas,karst groundwater channels are often accompanied by frequent heat exchange,directly affecting the quality of geothermal development.Therefore,conducting exploration of karst underground channels is of great significance for the development of urban underground space and the prevention of geological disasters in karst areas. Due to the high degree of spatial variability of karst channels,it is a challenge for conventional two-dimensional detection methods to complete the geophysical imaging,which in turn results in the difficulty of conventional karst detection.Geophysical exploration is widely used due to its wide applicability,large detection depth,and accuracy.However,different geophysical methods have different advantages in terms of detection depth,resolution and practicality.The Ground Penetrating Radar has the characteristics of high efficiency and high resolution,but it is mainly applied to the exposed and shallow-covered karst due to factors such as limited penetration depth,irregular terrain,and clay content.Electromagnetic and seismic exploration can generate better results in the exploration of buried karst.In addition,microgravity exploration can be used to detect shallow karst caves and fill-type karst caves.Electrical resistivity tomography(ERT)is the most commonly used geophysical method for karst exploration,and has been applied to various karst geological environments,such as cave exploration,the exploration of water-filled karst groundwater channel,the detection of urban underground cavity,and engineering surveys. In this study,3D ERT was used for fine detection of concealed karst underground channels in the urban area.Combining with geophysical numerical simulation and application examples,the effectiveness of 3D on karst underground channels with different filling types was analyzed.The research results show that 3D ERT has a significant improvement in data volume and resolution compared to 2D ERT.3D ERT can more intuitively characterize the three-dimensional electrical structure characteristics of the target body and has advantages in imaging karst groundwater channels.Through the three-dimensional electrical imaging of the karst groundwater channel in Yuanquan village,Wuhan City,the groundwater migration characteristics of the low-temperature hot spring are revealed.The analyses of geophysical prospecting and drilling show that two low-temperature hydrothermal vent groups in this area are directly connected by karst underground channels and connected with north-west fault structures,reflecting a hydrodynamic process.In this process,deep hot water firstly circulates along the fault fracture zone to shallow karst channels,and after its horizontal migration at a certain distance,deep hot water exposes at the surface in the form of spring near the fracture zone,and the contact zone of carbonate rock and schist. In this study,the three-dimensional electrical structure imaging of karst groundwater channel near the hot spring point has been jointly realized by geophysical exploration and drilling,and the trends of fractured fault zone and karst channel have been displayed.Study results show that the low-temperature hydrothermal spring is connected to the karst groundwater system through deep faults.In view of this,it is proposed to carry out systematic geothermal explorationin the area to find out the hydrogeological conditions of hydrothermal spring,the groundwater circulation and heat interaction processes.In addition,the study results may provide support for the temperature increase of the hydrothermal spring and for the development of urban geothermal energy.关键词
三维高密度电法/隐伏岩溶/岩溶地下水通道/三维电性成像Key words
3D ERT/concealed karst/karst groundwater channel/three dimensional electrical imaging分类
天文与地球科学引用本文复制引用
刘道涵,徐俊杰,齐信,邬健强..基于高密度电法的城市岩溶地下水通道三维电性成像[J].中国岩溶,2023,42(6):1331-1338,8.基金项目
本文得到了国家自然科学基金项目(42107485)、国家重点研发计划项目(2020YFC1512400和2018YFC 800804),中国地质调查局项目(DD20221734)的联合资助. （42107485）
