摘要
淮南市八公山区原肥皂厂近些年出现大规模的岩溶塌陷地质灾害,为了查明该调查区地下溶洞、裂隙管道等不良地质体的发育位置,笔者采用高密度电测深法、音频大地电磁法和地震折射法对塌陷区进行野外实验研究,研究结果显示:受滨河浅滩第四系淤泥低阻覆盖层的影响,高密度电测深法和音频大地电磁法测量的视电阻率值偏小,普遍小于200Ω·m,对低阻异常体识别度很低,很难通过视电阻值大小来准确判定基岩与低阻异常体之间的相对空间位置,相比之下,地震折射法受低阻覆盖层的影响较小,覆盖层与基岩之间纵波速度相差很大,实验得出,河床淤泥层纵波速度小于1000 m/s,第四系含砂黏土层纵波速度在1000～2200 m/s之间,基岩纵波速度大于3000 m/s,基岩与覆盖层之间的溶蚀层位纵波速度介于2200～3000 m/s之间.研究结果表明,在滨河浅滩第四系淤泥层等低阻覆盖层的影响下,高密度电测深法和音频大地电磁法测量的视电阻率值偏小,仅仅依靠视电阻率值来判定基岩与低阻异常体之间的相对空间位置不够严谨,在此基础上采用地震折射法,利用基岩、低阻覆盖层与溶蚀层之间的纵波速度差异,能够更加准确的划分并圈定覆盖层、溶蚀层和基岩面的空间位置.
In recent years,large-scale karst collapse occurred in the original soap factory of Bagongshan District,Huainan City.In order to find out the developmental position of underground karst caves and fractured pipeline in this investigation area,the author adopts high density resistivity method,audio magnetotellurics method and seismic refraction survey to conduct field experiments in the collapse area.The results show that the apparent resistivity measured by high density resistivity method and audio magnetotellurics method is small,generally less than 200Ω·m,under the influence of low resistance overburden of Quaternary alluvium in riverside shoal.The resolution capability of low resistivity anomalous body is very low,it is difficult to accurately determine the relative spatial position between bedrock and low resistance anomalous body by apparent resistivity value.In contrast,seismic refraction survey is less affected by low resistance overburden.The compressional velocity differs greatly between the overburden and the bedrock.The experiments show that the compressional velocity of apparent resistivity measured by high density resistivity method and audio magnetotellurics method is small under the influence of low resistance overburden such as Quaternary alluvium of riverside shoal.It is not rigorous enough to judge the relative space position between bedrock and low resistivity anomalous body only by apparent resistivity value.It is more accurate to divide and delineate their space position by the difference of compressional velocity among overburden,corrosion layer and bedrock on the basis of adopting seismic refraction survey.
作者
张伟
甘伏平
魏巍
管振德
刘伟
邬健强
ZHANG Wei;GAN Fu-ping;WEI Wei;GUAN Zhen-de;LIU Wei;WU Jian-qiang(Institute of Karst Geology,Chinese Academy of Geological Sciences,Guangxi Guilin 541004,China;Karst Dynamics Laboratory,ML R and GZAR,Guangxi Guilin 541004,China)
出处
《地球物理学进展》
CSCD
北大核心
2019年第2期832-839,共8页
Progress in Geophysics
基金
中国地质调查局地质调查项目(DD20160254
DD20190266)
中国地质科学院院控基金项目(YYWF201640)联合资助
关键词
岩溶塌陷
地质灾害
滨河浅滩
第四系淤泥层
Karst collapse
Comprehensive geophysical method
Riverside shoal
Quaternary alluvium
