充填型岩溶突水突泥灾害源的核磁共振表征与泥水识别方法

Characterizing and Identifying Types of Water and Mud Inrush Utilizing Magnetic Resonance Sounding for Tunneling Through Karst Areas with Filling Materials

隧道穿越富水岩溶地层时,为预报可能遭遇的突水突泥灾害类型、水量以及突出物信息,需提前探明掌子面前方地层含水量、渗透系数、导水系数等水文地质参数,从而对灾害源进行泥水识别。核磁共振探测(Magnetic Resonance Sounding, MRS)是一种能够直接探明地层水文地质特征的物探方法,基于MRS方法的这一优势,提出一种针对充填型岩溶突水突泥灾害源的核磁共振表征与泥水识别的方法,以期对突水突泥灾害进行预报并加以区分。通过引入Log-Gauss分布函数构建MRS弛豫时间的时空分布函数,用以表征不同灾害所对应的充填物特征;并对掌子面前方电阻率、含水量以及MRS弛豫时间分布进行三维离散,实现了对充填型岩溶突水突泥灾害源的核磁共振表征与建模。在此基础上,正演模拟了不同类型突水突泥灾害源的MRS响应信号,并分析了其响应特征与影响因素。基于灾害源的MRS响应信号特征,利用充填物含水量和MRS弛豫时间的时空分布函数建立了以充填型岩溶突水突泥灾害源的泥水识别因子作为对灾害源进行泥水识别的判据。

Water and mud inrush hazards can occur when tunneling through water-bearing karst strata. To predict these hazards, the distribution of volumetric water content, permeability, and hydraulic conductivity should be observed during tunneling operations. Magnetic resonance sounding（MRS） is a direct geophysical method for investigating these hydrogeological parameters. In this study, an MRS approach was developed for identifying different types of water and mud inrush hazards and characterizing the filling materials that can cause such hazards. Using a Log-Gauss distribution function, an MRS relaxation distribution function was proposed for characterizing different kinds of inrush hazards. These hazard sources were modeled using a 3-D discretization of the resistivity, volumetric water content, and MRS relaxation time distribution. Subsequently, the MRS responses for different inrush hazard types were stimulated and analyzed, and these responses were combined with the volumetric water content and MRS relaxation time to obtain a type factor that provides a direct judgment for characterizing water and mud inrush hazards.