Exploration on nonlinear geo-electrical structures to detect coal mine goafs using three dimensional borehole resistivity imaging discrete approach

摘要

Due to risks caused by goaf collapses in coal mines, it is urgent to detect coal mine goafs to prevent severe accidents. The borehole resistivity exploration techniques have been proven efficient in coal mine goaf detection. However, it is often difficult to accurately identify a goaf using a one dimensional (1D) or two dimensional (2D) geo-electrical model because of the presence of the nonlinearity in the geo-electrical structures. A three dimensional (3D) model can explore the nonlinear characteristics of coal mine goafs. Unfortunately, very limited studies report the 3D geo-electrical models in coal mine goaf detection. To address this issue, this work presents an original 3D borehole resistivity approach using borehole direct current resistivity imaging to detect goaf collapses. The forward and inverse mathematical models were established to support the presented approach. Numerical simulation results demonstrate that the proposed 3D borehole resistivity approach is valid not only for the detection of single-layer goaf but also for double-layered goaf. Hence, this newly proposed 3D approach has practical importance in exploring coal mine goafs.