自适应瞬变电磁波场反变换方法及其在隧道超前预报中的应用  

A self-adaptive inverse wavefield of transient electromagnetic method and its application in advanced forecast in tunnels

作　　者：王刚[1,2] 郑新 张书博 范克睿 WANG Gang;ZHENG Xin;ZHANG Shubo;FAN Kerui(Shandong Provincial Key Laboratory of Civil Engineering Disaster Prevention and Mitigation,Shandong University of Science and Technology,Qingdao 266590,China;School of Civil Engineering,Fujian University of Technology,Fuzhou 350118,China)

机构地区：[1]山东科技大学山东省土木工程防灾减灾重点实验室,山东青岛266590 [2]福建工程学院土木工程学院,福建福州350118

出　　处：《山东科技大学学报（自然科学版）》2023年第2期1-12,共12页Journal of Shandong University of Science and Technology(Natural Science)

基　　金：国家自然科学基金项目(52079077);山东省自然科学基金青年基金项目(ZR2022QE242)。

摘　　要：瞬变电磁法(TEM)是一种感知地下含水体,圈定隧道含水区范围的有效方法。从瞬变电磁信号中准确提取虚拟波场是刻画含水区形态边界的关键。为提取准确可靠的虚拟波场,需要解决核函数动态范围大、波场反变换方程高度病态和实现自适应求解等问题。本研究基于精细积分方法,结合缩短波场反变换数值积分区间的经验公式,提出优化的自适应波场反变换方法。结果表明,在对均匀半空间的数值模型计算中,对正演数据的拟合误差低于0.5%;在对H型地电断面的数值模型计算中,提取的虚拟波场具有合理准确的运动学特征;在对全空间HKH型模型的数值计算中,提取的虚拟波场突出不同深度的含水层边界,在整个观测时间段拟合程度高;对于隧道实测数据,虚拟反射波在富水区边界和电性界面附近响应明显,拟合误差低于5%,虚拟波场记录圈定的含水区与视电阻率分布规律相互印证且与钻井试验吻合,证实了该方法的有效性和可靠性。The transient electromagnetic method(TEM)is an effective method to detect and highlight water-bearing zones of tunnels.Accurate extraction of the pseudo-wavefield from the TEM signals is the key to characterizing the structure and boundary of water-bearing zones.To provide accurate and reliable pseudo-wavefield,the pseudo-wavefield extraction should tackle the large dynamic range of the kernel function,ill-posed inverse transform function,and self-adaptive solving.In this paper,an optimized self-adaptive method based on the precise integral method was proposed,which combined with the empirical formula to shorten the solving interval of the inverse wavefield transform.In the calculations of the half-space numerical model,the error of fitting with the forward data was less than 0.5%.In the calculations of the type-H geoelectric model,the extracted pseudo-wavefield had reasonable kinematical characteristics.In the calculations of the whole-space type-HKH model,the extracted pseudo-wavefield highlighted the boundary of the water-bearing zones of different depths and fitted well over the whole observation period.For the field data measured in a constructing tunnel,the pseudo reflective waves had apparent responses around the water rich boundary and the electrical interfaces,with a fitting error of less than 5%.The water-bearing zones highlighted by the pseudo-wavefield and the distribution laws of the apparent resistivity corroborated each other and were consistent with the results of the drilling test,verifying the effectiveness and reliability of the proposed method.

关 键 词：瞬变电磁法 波场反变换 自适应 超前预报 

分 类 号：U452.1[建筑科学—桥梁与隧道工程]