突涌水地质灾害是隧道修建面临的主要威胁,隧道掌子面前方赋存的突水灾害源——含水构造的三维定位已经成为亟待解决的关键难题。针对上述难题,提出了直流电阻率法三维反演成像超前探测方法。首先,建立了直流电阻率法超前探测三维全空间立体观测方式,针对测线附近的旁侧干扰严重这一关键问题,提出了干扰识别与去除方法,实现了掌子面前方三维有效信息的测量。综合线性反演方法和非线性反演方法的优点,提出了改进遗传算法与最小二乘法相结合的混合反演成像方法,既摆脱了对初始模型的依赖,又保证了反演进化效率。然后,重点对断层、裂隙、溶洞等典型的含水构造进行了系统的反演数值试验,获得了典型含水构造的三维成像特征和相应的地质解释依据,为实现由观测数据到三维成像再到地质模型的映射奠定了基础。最后,将直流电阻率法超前探测三维反演成像方法应用到模型试验和实际工程中,实现了含水地质构造的较准确三维定位,证明该方法具有良好的推广应用价值。
The water inrush hazards have become one of the major threats in tunnel construction, and the 3D localization of water inrush hazard sources (water-bearing structure) in front of the tunnel face has become a key problem to be solved urgently. For the above problem, the method of direct current (DC) resistivity 3D inversion tomography advanced detection is proposed. Firstly, 3D whole space stereoscopic observation mode of DC resistivity advanced detection is established. Due to serious flanking interference near survey line, an interference recognition and removal method is proposed, which realizes the measurement of 3D effective information in front of the tunnel face. By analyzing the advantages of linear and nonlinear inversion methods, a joint inversion tomography method which combines the improved genetic algorithms (GA) and the least-squares method is proposed. By use of this method, the dependence on the initial model is eliminated, while the efficiency of inversion is guaranteed. Then, numerical experiments for inversion tomography focusing on the faults, fractures and karst caves and other typical water-bearing structures are carried out systematically. And, the 3D tomography characteristics and geological interpretation criterion about typical water-bearing structures are analyzed and gained. An inversion map from observed data to 3D tomography and then to geological model is realized. Finally, the proposed method is applied in model tests and practical projects. Accurate 3D localization about water-bearing structures is realized, and it proves that this method has good application prospect.