基于磁场梯度张量缩并的岩石断层剪切滑移监测方法

现有的岩石断层剪切滑移监测方法不易直接测量沿剪切滑移方向的变形,仪器布设较繁琐,且无法监测岩石断层剪切滑移的中后期变形。基于磁场定位理论,采用磁性物质制作磁性智能石头,在岩石断层两侧的岩体分别布设磁性智能石头和磁传感探头,构建岩石断层剪切滑移大变形监测系统。基于磁场梯度张量缩并定位对磁性智能石头进行跟踪,实现岩石断层剪切滑移的中后期大变形监测。根据磁传感探头的精度和地球磁场梯度的影响,通过三维磁感应强度和磁场梯度的分析,其有效监测距离最大值为35 m,理论误差随着变形值与监测距离的比值、断层厚度与监测距离的比值的增大而增大。在岩石断层剪切滑移大变形监测的模拟试验中,在断层厚度为0.5~1.0 m、监测距离为5 m的情况下,变形监测的相对误差最大约为2%,可为磁测在岩石断层剪切滑移大变形监测的进一步研究和应用提供参考。

Deformation Monitoring for Rock Fault Shear Sliding Using Magnetic Gradient Tensor Contraction

The existing deformation sensors for rock fault shear sliding cannot directly measure the shear sliding deformation along the sliding surface. The arrangement of equipment is not convenient for the internal deformation monitoring and the deformation monitoring cannot be realized by the present technology during middle and later periods of sliding. Based on the magnetic localization theory, the magnetic smart rock is fabricated with magnetic material, andmagnetic smart rock and magnetic probe are embedded at two sides of rock fault respectively. So the large deformation monitoring system is established. The localization by magnetic gradient tensor contraction is used to track the motion of magnetic smart rock in order to realize the large deformation monitoring. With regard to the precision of magnetic probe and influence of earth magnetic gradient, the effective monitoring distance can reach 35 meters by the analysis of magnetic strength and magnetic gradient, and the theoretical error increases when ratio of deformation to monitoring distance or ratio of fault’s thickness to monitoring distance increases. In the simulation experiment, the maximum relative error is about 2% with the fault’s thickness ranged from 0.5 m to 1.0 m and monitoring distance of 5 m, which can be used as reference in the further study and practical engineering monitoring.