3D Model Construction Technology Of Local Coal Seam To Be Mined Based On Ground Penetrating Radar Wave Response

Unmanned mining of coal has become the development trend of coal mining industry in the future,which is of great significance to ensure the safety of coal mine production and improve production efficiency.Therefore,it is necessary to provide a coal seam model with high accuracy.However,most of the existing coal seam modeling data are mainly borehole data with large data intervals,and the accuracy of coal seam modeling is low.Moreover,the distribution of hidden geological anomalies inside the coal face affects the precision of coal seam modeling,and the coal seam model is difficult to meet the requirements of unmanned mining.The research objective of this thesis is to construct 3D model technology of local coal seam to be mined in response to ground penetrating radar wave.By using joint detection of multi-frequency ground penetrating radar antenna,the 3D spatial distribution of geological anomalies inside coal face and the structure information of coal seam are analyzed and determined,and the 3D morphological distribution of local coal seam to be mined is constructed.It provides high precision coal seam model for coal seam model revision,automatic cutting of shearer and unmanned mining of coal mine.First,the wave equation of electromagnetic wave is deduced in detail,the reflection and transmission characteristics of electromagnetic wave are analyzed,and the propagation loss of electromagnetic wave is expounded.At the same time,it introduces the working principle of ground penetrating radar,data acquisition methods,acquisition types and important parameters,which provides theoretical support for the forward simulation in the following chapters.Second,the forward modeling of the simple geological abnormal body in coal seam is carried out,and the forward modeling results under different shapes,sizes and center frequencies are obtained,and the response characteristics of the geological abnormal body are summarized.At the same time,forward modeling is carried out on the mixed anomalous bodies of gangue and void,coal seam fold and goaf,void and fracture zone,and void and water-rich area.The error value between simulated burial depth and real burial depth is less than 5%.By comparing the reflection phase between the target body and the incident wave,the relative size of the dielectric constant of the coal seam can be judged,which provides a certain basis for the classification of abnormal body.Again,a new method of detecting abnormal bodies in coal face based on multisection and linear interpolation is proposed.The response range of the anomalous body is roughly delineated by using Kirchhoff migration imaging.The imaging depth of each wave anomaly body was determined by multi-section joint analysis,and the exact position coordinates and specific dimensions of the anomaly body were determined by linear interpolation.At the same time,the three-dimensional model of coal seam cavity and fault and the physical test model of cavity were constructed for analysis.The polygon area was used to analyze the detection results,and the area error values were all below 10%.Then,a coal seam structure detection method based on multi-frequency radar fusion is proposed.The sliding window and wavelet transform are used to integrate the detection responses of various frequencies to improve the detection accuracy of the shallow part in the antenna detection area.The echo intensity model of radar wave in coal seam is established,and the interface information between coal,gangue and rock in coal seam is calculated by stratification identification technology.At the same time,the detection error is less than 10%,and the fusion image can identify the internal information of coal seam structure relatively accurately.Finally,using the above research methods,900 MHz and 1500 MHz radar antennas are used to detect coal seam models containing gangue and void in the laboratory.Data fusion method is used to integrate radar data of various frequencies to obtain the internal information of coal seam.At the same time,the geological anomaly location method is used to analyze and determine the profile dimension coordinates of the abnormal bodies in each survey line,and the detection error is controlled within10%.Finally,the three-dimensional surface distribution state of coal seam was constructed by coordinate transformation,data interpolation and surface fitting method in the direction of height.