任意各向异性三维直流电阻率巷道超前探测的并行Monte Carlo方法研究

Water inrush and flood accidents in tunnel are most dangerous geological disaster in coal mine and karst area, advanced detection of water-bearing structures in the front of tunnel face is the key problem needed to be resolved．Due to its high resolution and sensitivity to the low resistivity body, the direct current (DC) resistivity method is widely used in the advanced detection with several empirical prediction models available．However, only simple subsurface structure is presently considered in physical experiment or numerical modeling, it is very uncertain whether the developed prediction models are accurate and reliable for the actual complicate subsurface structures with arbitrary size and distribution of anomalous body. Moreover, anisotropic resistivity effect has not been considered so far for the advanced detection in tunnel, which may cause a terrible uncertainty. Monte Carlo (MC) method is used to solve any problem having a probabilistic interpretation relying on repeated random sampling. In this study, a prediction model will be developed for the advanced detection under the condition of arbitrary resistivity anisotropy, on the base of three-dimensional (3D) DC anisotropic resistivity modeling using finite elements (FE) on unstructured grids. We use parallel Monte Carlo method for the design of huge number of random complicated 3D models with anisotropy and carry out 3D resistivity FE modeling for these random models. The statistics results of the prediction for advanced detection in tunnel are analyzed to evaluate accuracy and reliability for different prediction models and its anisotropic effect. Our study provides a new way of quantitative analysis for the advanced detection in tunnel.

突水、透水事故是煤矿生产和岩溶地区交通隧道施工中极具危害的地质灾害，巷(隧)道掌子面前方含水构造超前探测是亟需解决的关键问题。直流电阻率法以其对低阻体反映敏感、分辨率高等优点在该领域得到广泛应用，并形成多种经验预测模型。然而实际地下结构复杂，异常大小不定且任意分布，目前由简单物理实验或数值模拟获得的预测公式不确定性较大。特别地，可能存在的电阻率各向异性使得这种不确定性更加难测，而迄今未见有各向异性情况下的超前探测研究。Monte Carlo(MC)方法用随机化思想解决非确定性问题。本项目基于任意各向异性电阻率三维非结构有限元数值模拟，建立各向异性条件下的超前探预测模型。引入MC方法随机生成大量各向异性三维复杂模型，进行有限元数值模拟并行计算，由各预测公式估计掌子面前方异常体距离，对估计结果统计处理，获得各预测模型准确度、可靠性及各向异性影响，为隧道超前探测准确性和可靠性定量化研究提供新途径

突水、透水事故是煤矿生产和岩溶地区交通隧道施工中极具危害的地质灾害，巷(隧)道掌子面前方含水构造超前探测是亟需解决的关键问题。直流电阻率法以其对低阻体反映敏感、分辨率高等优点在该领域得到广泛应用，并形成多种经验预测模型。然而实际地下结构复杂，异常大小不定且任意分布，目前由简单物理实验或数值模拟获得的预测公式不确定性较大。特别地，可能存在的电阻率各向异性使得这种不确定性更加难测，而迄今未见有各向异性情况下的超前探测研究。本项目实现了任意各向异性电阻率三维非结构有限元数值模拟，国际上第一次建立起各向异性条件下巷道超前探预测模型及其准确性、可靠性的定量评价。各向同性和各向异性条件下的超前探数学预测模型对比表明，如果不考虑各向异性的影响，各向同性预测模型的结果将夸大了掌子面前方低阻含水断层的距离，造成实际巷道采掘过程中极大的透水危险。Monte Carlo方法用随机化思想解决非确定性问题，本研究引入Monte Carlo方法随机生成大量各向异性三维复杂模型，进行有限元数值模拟并行计算，由各预测公式估计掌子面前方异常体距离，对估计结果统计处理，获得各预测模型准确度、可靠性的定量评价，结果表明我们提出的预测模型准确度、可靠性是最好的。同时，关于掌子面前方低阻含水断层大小、各向异性大小对超前探测影响规律的讨论，显示了Monte Carlo方法应用于超前探测有非常重要的实际意义。本研究顺利完成了项目预定的各项目标任务，并取得一些对实际巷道采掘过程中突水灾害风险控制具有指导意义的成果。