滨海城市地质结构电阻率法三维模拟与应用

3D simulations of geological structures in coastal cities using a electrical resistivity method

在我国滨海城市地下工程建设中,精准定位断层、孤石及其他不良地质体是亟待解决的技术问题之一。基于滨海城市地质特点,针对高密度电阻率法开展了三维数值模拟研究,获得了覆盖层电性和厚度对高密度电阻率探测的影响结果,以及探测目标体大小和埋深发生变化时的直流电场特征。研究结果表明:覆盖层与探测目标的电阻率的差异大小是决定覆盖层影响的主要因素,对于低阻断层破碎带,覆盖层电阻率越高,破碎带的响应越突出。在中高阻覆盖条件下,孤石埋深越浅越容易获得揭露,尺寸越大其高阻特征越突出。在青岛市地铁5号线勘查中,高密度电阻率法在断裂破碎带和孤石探测中显示出关键作用,验证了方法的应用效果。研究成果可为滨海城市工程勘查方法选择和工作参数确定提供依据。

For the underground construction of coastal cities in China,there is an urgent need to accurately position unfavorable geobodies such as faults and boulders.Based on the geological characteristics of coastal cities,this study conducted 3D numerical simulations using a high-density resistivity method,determining the effects of the electrical properties and thickness of the overburden on the survey results,as well as the DC electric field characteristics varying with the sizes and burial depths of detection targets.The results show that the resistivity difference between the overburden and the targets serves as a critical factor in determining the influence of the overburden.For low-resistivity fracture zones,a higher resistivity of the overburden signifies more prominent responses from the fracture zone.Under middle-to high-resistivity overburden conditions,shallowly buried boulders can be easily found,and larger boulders exhibit more significant high-resistivity characteristics.In the exploration along the Qingdao metro line 5,the high-density resistivity method played a vital role in exploring fracture zones and boulders,verifying the effective application effects of the method.The results of this study provide a basis for selecting engineering exploration methods and determining operating parameters in coastal cities.