Numerical Simulation Study On Abnormal Influence Characteristics Of Resistivity Advance Detection In Tunnel And Borehole And Multi-directional Stereo Detection Effect

As coal seam mining gradually develops deeper,coal mine safety is of great importance.Conducting in-depth research on three-dimensional numerical simulation of resistivity advanced detection in tunnel and borehole is beneficial for the precise positioning of anomalous bodies and obtaining three-dimensional spatial anomaly information.In this paper,the adaptive unstructured finite element method based on dual-weighted posteriori error estimation is applied to the three-dimensional numerical simulation study of resistivity advanced detection in tunnel and borehole.The applicability and accuracy of this method in advanced detection simulation are verified through an infinitely large vertical plate model.Based on previous research,this paper focuses on the numerical simulation study of the underground resistivity advanced detection in tunnel and borehole of abnormal influence characteristics and multi-directional stereo detection effects.Firstly,the resistivity advanced detection in tunnel is conducted by simulating the distance and resistivity of anomalous bodies,verifying that the extreme value position of the abnormal curves is linearly related to the position of anomalous bodies.Then,the effects of side anomalous bodies,tunnel size,and multi-layer strata are numerically simulated in the advanced detection.It is shown these parameters cause different degrees of influence on resistivity advanced detection in tunnel,but not overshadowing the response characteristics of the tunnel’s forward abnormalities.To reduce these abnormal effects,this paper proposes resistivity advanced detection in borehole using pole-pole array and pole-dipole array to numerically simulate in different aspects and compare the results with advanced detection in tunnel.The results are as follows.Resistivity advanced detection in borehole is more directly and accurately reflecting the actual position of anomalous bodies ahead of the tunnel without relying on empirical formulas or graphical methods.The characteristics of apparent resistivity anomaly curves change with the resistivity,distance and thickness of anomalous bodies.The pole-dipole array can also obtain stronger abnormal responses than the pole-pole array.In layered strata,the overall trend of the abnormal curve is greatly influenced by the resistivity of the strata outside the source layer.The influence of anomalous bodies orientation,tunnel cavity and anomalous bodies at side on resistivity advanced detection in borehole is relatively small.In fact,the abnormal curves of the resistivity advanced detection in tunnel can only infer the distance of anomalous bodies.The number of boreholes in tunnel are limited.In order to obtain more spatial information of anomalous bodies for accurate advanced detection,this paper studies a data acquisition method for multi-directional stereo three-dimensional advanced detection in borehole.The detection effect of this method is explored by Inexact Gauss-Newton three-dimensional inversion with a single anomalous body,two anomalous bodies and an inclined plate model.The position,shape and size of anomalous bodies are accurately reflected with good inversion effect.This preliminary result indicates that the multi-directional stereo three-dimensional advanced detection method in borehole is feasible in theory,and further research needs to be carried out in conjunction with actual work.