摘要
文章采用高密度电阻率法和音频大地电磁法对贵州省威宁县猴场滑坡区进行探测,探究从浅部到深部岩溶及裂缝发育情况、岩溶滑坡体底界面形态及滑坡体结构特征.通过音频大地电磁法划分了滑坡区地层结构,发现滑坡区发育浅部和深部两层岩溶,尤其在灰岩与泥页岩界面处的深部岩溶,加之煤层开采形成的采空区,是触发滑坡的背景条件;通过高密度电阻率法探测出的裂缝及岩溶发育区域,是滑坡体进一步位移拉裂的脆弱区.分析认为,岩溶发育破坏了滑坡体原来的整体性,使岩溶山体劣化成零散块体,是导致滑坡的关键因素之一.
Abstract
The frequent occurrence of landslides in China has done great harm to people's lives and property.In the stability analysis of landslides and the design of treatment scheme,the application of geophysical technologies has become a frontier research field in engineering and environment in terms of interdisciplinary development and application.The Houchang landslide in Weining county,Bijie City,Guizhou Province is a typical karst landslide.The landslide area is dominated by karst peak-cluster depressions or gullies,in which limestone strata are widely distributed,and karst is strongly developed.Since the collapse and landslide in 2006,the scale of tensile cracks in rock mass has gradually increased.In order to explore the causes of collapse,scholars have deduced the collapse process,established the conceptual model of landslide and studied the karst hydrogeological conditions.However,due to the lack of detection data,the structural characteristics of landslides have not been fully understood.In this study,the high-density resistivity method and audio-frequency magnetotelluric method were used to detect the landslide area,and the structural characteristics of landslides were revealed from the development of shallow karst and cracks,and the bottom interface of karst landslide.The stratigraphic structure of landslide area was divided by audio-frequency magnetotelluric method,and the lithologic interface between Qixia-Maokou Formation and Liangshan Formation was defined according to the electrical characteristics of different lithologic strata.Furthermore,the clastic rocks of Liangshan Formation in some areas were divided into shale,carbonaceous shale and coal seam.It is found that there are two layers of karst development:one is the karst fracture zone in the shallow part of the karst mountain,which is filled with mud and other low-resistivity substances,and the development depth of the karst layer gradually increases from northeast to southwest;the other is the deep karst fracture zone at the bottom interface of limestone in Qixia-Maokou Formation,which is mainly developed in the southern part of the landslide mountain,showing low-resistance characteristics.These two layers of karst structures provide a weak layer for landslide regeneration.Cracks and karst development areas have been detected by high-density resistivity method.There are three mountain cracks in the landslide mountain,including one with a large front edge and two secondary cracks at the rear edge.The cracks show the characteristics of"local high-resistance zone in the low-resistance layer on the surface and vertical low-resistance zone in the underground high-resistance rock mass".In addition,some shallow vertical karst fracture zones were detected,which destroyed the integrity of karst mountain.With the development of karst,karst mountain deteriorated into scattered fragments,which may gradually collapse or landslide under some extreme conditions.It is considered that the development of karst,especially the deep karst at the interface between limestone and shale,is one of the key factors leading to landslides.Together with the goaf formed by coal seam mining,karst development is the background condition that may trigger landslides,which in turn can deteriorate karst mountains into scattered blocks and gradually into collapses and landslides.The combination of audio-frequency magnetotelluric method and high-density electrical method can effectively detect the structural characteristics of karst landslides,and can comprehensively obtain the characteristics of karst spatial development,crack location and distribution of landslide bottom interface,which can provide an important basis for in-depth and comprehensive analysis of landslide stability.
基金项目
广西重点研发计划项目(2020AB22013)
广西重点研发项目(桂科AB23026062)
广西壮族自治区地质环境监测站项目(桂自然资函[2021]415)
中国地质科学院岩溶地质研究所基本科研业务费项目(2021007)
国家科技期刊平台
NSTL
万方数据