Study on measuring methods for three-dimensional morphology of coal mining subsidence ground fissures and accuracy evaluation

Coal mining induces the development of ground fissures,and quantitative description of the three-dimensional morphology of ground fissures has important scientific significance.In order to obtain the three-dimensional morphology information of the coal mining subsidence ground fissures,and to compare with the traditional steel ruler measurement method,three new methods for determining the morphology of ground fissures were studied and used in this paper,namely,three-dimensional laser scanning method,three-dimensional laser scanning combined with perfusion gypsum slurry method,and ground penetrating radar scanning method.In addition,their measurement accuracy and technical characteristics were studied by experimental application.These results show that the traditional steel ruler measurement method can obtain fissure width,length and depth,but it cannot establish the three-dimensional model of fissures,and cannot obtain other three-dimensional information such as volume and surface area.The three measurement methods proposed in this paper are feasible and can obtain three-dimensional models of fissures.Their technical features are:The three-dimensional laser scanning fissure measurement method can obtain the three-dimensional morphology digital model,but the deep information of the fissure is difficult to detect.In the 10 cm step height ground fissure detection test,the depth,area,and volume of ground fissures obtained by the three-dimensional laser scanning method were 47%,59%,and 77% smaller than those of the perfusion gypsum slurry method,respectively.Three-dimensional laser scanning combined with perfusion gypsum slurry method can completely obtain three-dimensional morphology information such as fissure width,depth,length,volume and area.Among them,the deviation of the measured fissure width and depth were lower than 13% and 25% compared with those of the steel ruler measurement method,and the accuracy were higher.However,the detection operation is destructive.The ground penetrating radar scanning method,although complicated to operate,can obtain the three-dimensional morphology digital model of fissures,and is suitable for the small-fissure observation in the field and the fissure morphology model acquisition in the indoor simulation experiment.This study provides a variety of detection methods for the acquisition of ground fissure morphology information,which has certain significance for the ecological treatment of coal mining subsidence areas,and provides new detection technology support for the research work of ground fissures.