Study On The Mine Multi-wave Scattering Imaging Method And Its Application

Mine seismic wave field has response characteristics to the geological structure of mining face.However,effective reflected waves are difficult to be formed and received under the constraints of the mine complicated receiving conditions and the inhomogeneity of small structures.And multi-directional and multi-type seismic waves will be aliased under full space effect.Scattered waves derived from Huygens-Fresnel principle cover all types of waves,which are more suitable for the detection of mine geological structure than reflected waves.Multi-wave multi-component seismic exploration with wave field separation as the core can make up for the deficiency of single wave detection and is suitable for mine seismic wave field.Therefore,the research of mine multi-wave scattering imaging method is of scientific value and practical significance to improve the detection accuracy of mine geological structure,enrich the theory and application of mine geophysical fine detection method,and perfect the geological support system.Based on the kinematics and dynamics of seismic waves,the scattered-wave imaging method established on the concept of equivalent offset is studied.Considering the polarization characteristics of seismic waves in coal measure strata,the polarization filtering function is constructed by using the method of calculating the instantaneous polarization parameters of adaptive windows.Based on the difference of velocity between the common scattering point gather and the converted wave,the converted wave suppression factor is designed.These can provide a vector wave field separation method for mine scattered-wave signal.In view of the exploration demand of heading and working face,the equivalent offset formula of scattered-wave laneway advanced detection is established by designing the equivalent virtual line perpendicular to the laneway heading direction.The equivalent offset formulas of two-dimensional co-scattering points under single laneway observation and double laneway observation and of three-dimensional co-scattering points under the transmission observation of working face are established.A multi-wave scattering imaging method is proposed with establishing the multi-wave scattering detection models suitable for mine space,synchronously carrying out integration of the separation of the vector wave field and the mapping of the co-scattering point gather.And the method is programmed by a mixture of Visual C++ and MATLAB.The feasibility of mine multi-wave scattering imaging was verified by numerical simulation.(1)The characteristics of scattering wave field and the location of true scattering point of the two-dimensional model of falling pillar,fault,three-dimensional model of falling pillar in working face,and the model of different dip fault in front of rock laneway and the advanced fractured coal seam in coal laneway are classified and contrastively analyzed.The polarization characteristic difference parameters of P waves,S waves and channel waves are verified.The development and interference degree of different types of waves should be considered as a whole when selecting waves for imaging.(2)Comparing and verifying the co-scattering points gathers of different target types of waves after vector wave field separation,it has the advantages of accurate extraction of scattered waves produced by endpoints and true scattering points,high folds and elimination of interference wave.The results of multi-wave scattering imaging are accurate,reliable and can avoid symmetrical illusion.(3)The criteria of setting parameter for mine multi-wave scattering imaging are given by analyzing the main parameters of mapping the multi-wave co-scattering points gathers and separating the wave field.Laboratory and field tests of mine seismic three-component actual wave field based on triaxial velocity and acceleration geophones were carried out.By analyzing the time-frequency domain and polarization parameters of seismic wave field in thin coal seam,the signal characteristics of actual seismic wave field in mine space are revealed,and the field applicability of the two types of geophones is evaluated.These can provide practical application guidance for mine seismic exploration.The actual field detection results of abnormal geological structure in mine laneway and working face show that the mine multi-wave scattering imaging method in this dissertation can complete multi-wave field imaging of P waves,S waves and channel waves.Compared with conventional reflected wave imaging,it has advantages of data redundancy,high folds and more accurate imaging,which provides field application value for ensuring mine safety production.