胶东北部海岸带厚覆盖区近地表地层结构分析——基于高密度电阻率法和探地雷达法探测结果

Analysis of Near-surface Strata Structure in the Thick-covered Coastal Zone of Northern Jiaodong Detection Results Based on High-density Electrical Method and Ground Penetrating Radar Method

胶东北部海岸带覆盖区的地表地质露头少,岩体、地层和构造等地质现象难以通过地表露头直接观察。为查清研究区周边海岸带覆盖区浅部地层的分布情况,评价城市地下空间开发的适宜性,应用高密度电阻率法和探地雷达法联合开展近地表地质调查工作。通过调查,初步查明了研究区周边海岸带覆盖区浅部地层岩性、各岩性层的顶底界面埋深及其变化规律。研究区东侧细砂层底界面的平均埋深为23 m,花岗岩顶界面的平均埋深为37 m;研究区西侧粉砂层底界面的埋深为2~2.5 m,细砂层底界面的平均埋深为24 m,花岗岩顶界面的平均埋深为35 m。沉积层的沉积厚度由海向陆逐渐变薄,花岗岩基岩的顶界面埋深由海向陆逐渐变浅。高密度电阻率法与探地雷达法联合探测的各岩性层界面深度与钻孔资料一致,可为探究研究区周边海岸带覆盖区的浅部地层分布情况及城市地下空间开发适宜性评价等工作提供地球物理依据。

As few surface geological outcrops are detected in the coastal zone of north Jiaodong,geological phenomena such as rock mass,strata and structure are difficult to directly observe through surface outcrops.In order to find out the distribution of shallow strata in the coastal zone around study area and evaluate the suitability of urban underground space development,high density resistivity method and ground penetrating radar method are used to carry out near surface geological survey.Through investigation,the shallow strata lithology,the buried depth of each lithology layer at the top and bottom interface and its variation rule in the coastal zone covering study area are preliminarily identified.On the east side of study area,the average buried depth at the bottom of the fine sand layer is 23 m,and the average buried depth at the top of the granite layer is 37 m.On the west side of study area,the buried depth of silt layer bottom is 2~2.5 m,the buried depth of fine sand layer bottom interface is 24 m on average,and the buried depth of granite top interface is 35 m on average.The thickness of the sedimentary layer gradually thinned from sea to land,and the buried depth of the top interface of the granite bedrock gradually shallower from sea to land.The interface depth of each lithologic layer detected by the high-density resistivity method and ground penetrating radar method is consistent with the borehole data,which provides geophysical basis for the shallow strata distribution study in the coastal zone around study area and evaluating the suitability of urban underground space development.