基于三维电测量的复杂地质构造识别及参数估计方法

COMPLEX GEOLOGICAL STRUCTURE INDENTIFICATION AND PARAMETER ESTIMATION METHOD BASED ON 3D RESISTIVITY MEASUREMENT

在实际工程中,地质体通常呈现复杂的三维空间分布,基于二维介质假设的传统高密度电法难以准确反映其空间位置及走势,三维高密度电法能更好处理此类问题,但长期以来由于数据采集与处理难度大,其应用受到限制。为研究三维高密度电法在空间形态复杂的不良地质体勘探中的应用效果,比较其与二维电法的差异,本文首先研究三维高密度电法的工作原理及数据处理方法,然后通过现场试验进行应用研究,利用二维及三维高密度电法对福建寿宁银矿采空区进行勘探,并利用三维激光扫描对结果进行验证。成功实现了复杂地形条件下240道电极的三维电法数据采集,并引入基于光滑约束的最小二乘法完成三维电法数据的反演。研究结果表明,三维激光扫描能精确获取采空区的形态及走势,为电法结果提供可靠的验证;三维高密度电法能准确反映浅层电阻异常体的位置及走势,相比于二维高密度电法,其反演结果收敛,排除了深层的干扰信息,降低了多解性。

Geologic body usually presents complex three-dimensional spatial distribution in actual engineering.Traditional high-density resistivity method based on the assumption of two-dimensional medium may not be able to accurately reflect its spatial position and trend,while three-dimensional high-density resistivity method can handle such problems perfectly.But it is restricted in application due to the difficulty in data acquisition and processing.This paper attempts to study the effect of three dimensional high-density resistivity method in the exploration of unfavorable geologic bodies with complex spatial form and compare the difference from two-dimensional resistivity method.This paper firstly studies the principle and data processing method of three-dimensional high-density resistivity method,and then carries out the application research through the field test which is based on the goaf in Fujian Shouning.Both two-dimensional and three-dimensional high-density resistivity methods are used in the exploration.The results are verified by three-dimensional laser scanning.It successfully realizes the threedimensional resistivity data acquisition of 240 electrodes in complex terrain,introduces the least square method based on the smooth constraint technique and finished the inversion of three-dimensional resistivity data.The research results show that three-dimensional laser scanning can accurately acquire goaf form and trend,which verifies the results of the resistivity method reliably.The three-dimensional high-density resistivity method can accurately reflect the location and trend of abnormal resistance.Compared with the two-dimensional high-density resistivity method,its inversion converges,which eliminates the deep interference information and reduces multiplicity of solution.