Characterization of a Karst Site using Electrical Resistivity Tomography and Seismic Full Waveform Inversion
Characterization of a Karst Site using Electrical Resistivity Tomography and Seismic Full Waveform Inversion
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使用电阻率层析成像和地震全波形反演表征喀斯特场地
DOI：
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
K. C. Davis
中科院分区：
文献类型：
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作者：
M. Kiernan;D. Jackson;J. Montgomery;J. Anderson;Brannon W. McDonald;K. C. Davis
岩溶地质的特点是存在天坑和空洞，这可能会对现有的基础设施构成重大风险。在活跃的采石场附近经常可以观察到天坑的形成，那里的降水操作会改变区域地下水流动模式，导致地面下沉和空洞形成增加。在这些地区，识别可能容易形成天坑的位置需要有能力绘制岩石内的溶解特征图。传统的岩土勘探本身并不能很好地适应这项工作，因为它们只提供离散点的地下信息，因此可能会遗漏岩石中的空隙。地球物理方法提供了一种方法来产生岩石表面的连续剖面和可能的空洞位置，但在岩溶地质中解释这些测试的结果可能是具有挑战性的。这项研究使用了阿拉巴马州中部州际公路沿线以前有天坑活动的地点的2D电阻率和地震勘测。该地点毗邻一个石灰石采石场。利用二维偶极子-偶极子阵列和强梯度阵列采集了电阻率数据。利用全波形反演(FWI)技术对地震数据进行处理。然后将从地球物理调查中解释的地下剖面与以前现场调查中的钻孔数据进行比较。地球物理调查的结果发现，在基岩深度变化和确定可能的天坑特征方面，与钻孔数据一致。考虑了与每种调查类型有关的潜在限制和误差来源。
Karst geology is characterized by the presence of sinkholes and voids, which may pose significant risk to existing infrastructure. Sinkhole formation is often observed near active quarries, where dewatering operations can alter regional groundwater flow patterns leading to subsidence and increased void formation. In these areas, identifying locations which may be susceptible to sinkhole formation requires an ability to map dissolution features within the rock. Traditional geotechnical explorations alone are not well-suited to this effort as they only provide subsurface information at discrete points and therefore may miss voids within the rock. Geophysical methods offer a means to produce continuous profiles of the rock surface and possible locations for voids but interpreting the results of these tests in karstic geology can be challenging. This study uses 2D electrical resistivity and seismic surveys at a site with previous sinkhole activity along an interstate in central Alabama. The site is adjacent to a limestone quarry. Resistivity data is collected using 2D dipole-dipole and strong-gradient arrays. The seismic data is processed using a full waveform inversion (FWI) technique. Subsurface profiles interpreted from the geophysical surveys are then compared to borehole data from previous site investigations. Results from the geophysical surveys are found to be consistent with borehole data regarding variation of bedrock depth and identification of possible sinkhole features. Potential limitations and sources of error pertaining to each survey type are considered.