【摘要】 塌陷已成为岩溶区最主要的地质灾害。本文以广东省高要市蛟塘镇塱下村岩溶塌陷区为例,结合钻探资料,应用高密度电阻率成像法与微动谱比法联合探测塌陷区背景地质结构和构造。通过区内外14个已知钻孔旁的微动测量,建立了微动特征频率与覆盖层厚度的数学关系,并应用于塌陷区覆盖层厚度的估算。高密度电阻率成像反映出岩土电阻率在水平方向和垂直方向上的变化,揭示了地下地质结构;微动谱比法揭示了探测场地的基岩起伏形态,结合地层岩性推断了古河道的存在并确定了其边界及延伸方向,与高密度电阻率成像法联合进行地质解译,推断了基岩内断层发育的空间位置、走向等特征。综合该两类物探技术探测成果和钻探资料表明,塌陷位于古河道内,并沿古河道方向发育,其方向与区域北东向构造走向方位一致。更多还原

【Abstract】 Collapses have become one of the most important geological hazards in karst areas. This paper takes a karst collapse area in Langxia village,Jiaotang town,Gaoyao City,Guangdong Province as an example to present probing geological conditions for such hazard using high-density resistivity imaging and microtremor spectral ratio methods combing with borehole data. In terms of measurements nearby 14 boreholes,we established the mathematical relationship between characteristic frequency of microtremors and cover thickness,which was used to calculate thickness of the cover in the collapse area. Profiles of high-density resistivity imaging reflect the variations of resistivity of rock and soil in horizontal and vertical directions,permitting to delineate the geological structure in the subsurface. In combination with lithology,the measurement of microtremors helps reveal the relief of bedrock in the study area,allowing us to infer existence of the ancient channel including its boundary and extension. Combining the results of two methods,we have deduced the spatial position and the trend of faults in the bedrock. Integrating the geophysical prospecting and borehole data suggests that the collapse is located in the paleochannel,which developed along its course,with a direction consistent with NE trending structure in this region.更多还原