广州南沙厚覆盖区近地表地层结构分析:基于二维地球物理多方法探测结果  

Near surface stratigraphic structure analysis in Nansha of Guangzhou thick overburden area:based on multi method results of 2D geophysics exploration

作　　者：陈松 陈长敬 罗士新 刘圣博 赵信文 曾敏 西永在[2] CHEN Song;CHEN Changjing;LUO Shixin;LIU Shengbo;ZHAO Xinwen;ZENG Min;XI Yongzai(Wuhan Center(Central South China Innovation Center for Geosciences),CGS,Wuhan 430205,Hubei,China;Ministry of Natural Resources,Institute of Geophysical and Geochemical Exploration,CAGS,Langfang 065000,Hebei,China)

机构地区：[1]中国地质调查局武汉地质调查中心(中南地质科技创新中心),湖北武汉430205 [2]中国地质科学院地球物理地球化学勘查研究所,河北廊坊065000

出　　处：《地质通报》2023年第1期168-179,共12页Geological Bulletin of China

基　　金：国家重点研发计划项目《地下水源智能可靠勘测关键技术及装备研发》(编号:2020YFC1512401);国家自然科学基金项目《基于钻孔的地下水环境垂直结构分层探测与地层信息快速提取技术》(批准号:42107485);中国地质调查局项目《广州多要素城市地质调查》(编号:DD20190291)。

摘　　要：广州南沙地区的第四系覆盖层埋深、隐伏构造分布、下伏岩性特征直接影响该区重大基础工程建设。因地层结构成像地球物理方法适用性各不相同,基于该区域已有的工作基础,优选了高密度电法、微动、音频大地电磁测深(AMT)3种方法,辨识地层分布特征。基于各方法的采集参数试验、数据处理原理及处理步骤,以及探测南沙新区重点开发地区下的地下空间试验,总结了适合于探测该区域地下空间的3种物探手段。①高密度电法可较准确地分辨覆盖层与基岩分界面,反演的覆盖层深度与多处钻孔资料较吻合,可用多条剖面控制研究区的覆盖层厚度空间分布特征;②AMT探测深度大,在试验中有效探测深度达500 m,横向分辨率高,反演的电阻率断面可确定深部断裂和隐伏岩体分布;③微动探测抗干扰能力强,对特殊场地背景可进行无损探测,解译的视S波速度分层结构,剖面反映的分层效果好。结合剖面内的钻孔资料,采用高密度电法、微动、AMT探测,可从电阻率、横波速度多参数准确地辨识地下空间地层结构特征,为城市地下空间开发提供基础资料。The buried depth of Quaternary overburden,the distribution of concealed structures and the underlying rock characteristics directly affect the major infrastructure construction in Nansha,Guangzhou.Compared with the previous work methods mainly relying on drilling to find out the near surface stratum structure,this paper uses nondestructive geophysical methods to detect the near surface stratum distribution characteristics,which is more environmentally friendly,green and convenient.The applicability of geophysical methods for stratigraphic structure imaging is different,based on the existing work foundation in this area,in this paper,three methods of high density resistivity method,microtremor and audio magnetotelluric sounding(AMT)are optimized to identify the characteristics of stratigraphic distribution.Based on the acquisition parameter test,data processing principle and processing steps of each method,as well as the underground space test in the key development area of Nansha new area,the experience of three geophysical exploration methods suitable for detecting the underground space in this area is summarized.①High density resistivity method can accurately distinguish the interface between overburden and bedrock,and the inversion overburden depth is consistent with the data of many boreholes.Multiple profiles can be used to control the spatial distribution characteristics of the thickness of overburden in the whole survey area.②AMT has a large detection depth,in this paper,the effective detection depth is up to 500 meters and the lateral resolution is high.Inversion of resistivity section can determine the distribution of deep faults and concealed rock mass.③Microtremor detection has strong anti-interference ability,it can be used for nondestructive detection of special site background.The interpreted apparent S-wave velocity layered structure has good layered effect of profile response.Combined with the borehole data in the profile,using high density electrical method,microtremor and AMT detection,the

关 键 词：高密度电法 音频大地电磁 微动 城市地下空间结构 成像 地质调查工程 

分 类 号：P631[天文地球—地质矿产勘探]