Research For Coalbed Goafs With Geophysical Methods

Coal seam goaf has always been a major factor in the safe mining of coal mines.With the increasing emphasis on coal mine safety production in China,the detection of the location and extent of the goaf has gradually become one of the important tasks of geophysical exploration.In order to achieve accurate detection of coal mine goaf,this comprehensive use of seismic and electrical methods and other methods for comprehensive detection.Firstly,the formation and development process of coal mine goaf are studied,and the geological characteristics of coal seam goaf are summarized.The change of the overlying strata after coal seam mining can be divided into three zones: the fall zone,the fracture zone and the curved zone.The coal seam goaf can be divided into complete goaf,destructive goaf and small coal mine according to the degree of damage.Gob area;according to the time division of formation,it can be divided into ancient goaf,modern gob and modern gob.Secondly,the seismic geological conditions of the mining area are analyzed.The goaf formed after the completion of coal seam mining forms a so-called "three belts" or cavities according to the passage of time.The coal seam mining area was simulated by two-dimensional seismic forward modeling software.The results show that the reaction on the forward time profile is attenuated and nearly disappeared when the coal seam goaf is inflated;when the goaf is filled with water,it is positive.The response of the time profile is the enhancement of the reflected wave energy;when the coal seam goaf collapses,the response on the forward time profile is the displacement or disappearance of the reflected wave in the same phase.And the scale of the reaction on the time profile is slightly larger than the actual range of coal seam formation into the goaf.Thirdly,the forward simulation of coal seam goaf is carried out by using the forward modeling software of electric method,and the variation law is analyzed and summarized.When the goaf is inflated and not filled with water in the hollow goaf,the cross-sectional view shows a high resistance with a small amplitude,but the anomaly is not obvious;when the goaf is a water-filled hollow goaf,the sectional view It is shown as an obvious low-resistance anomaly;when the coal seam goaf is collapsed and not filled,the goaf shows a high-resistance anomaly on the section view;when the coal seam goaf collapses and fills with water,the section shows It is a low resistance abnormality.Finally,based on the example of a mine in Jindong area,on the basis of earnestly grasping the field construction and data interpretation,the law of the reaction of geophysical data in the goaf is summarized.seismic interpretation and comprehensive interpretation are proposed to detect geophysical interpretation methods in goaf.Through the analysis of the application examples,the methods and technical process steps of the integrated geophysical exploration goaf are summarized.It provides a useful reference for the use of integrated geophysical methods to detect goafs.