Study On The Method Of Subsidence Deformation Monitoring In Mining Areas Based On Airborne LiDAR Technology

The surface subsidence caused by coal mining will seriously affect the ecological environment of the subsidence area.The subsidence monitoring is a reliable method to master the law of subsidence.However,the traditional subsidence monitoring method can only obtain the settlement data of a few discrete points along the strike and dip main sections of the working face,and cannot fully reflect the subsidence deformation of the whole working face.In recent years,3D scanning,In SAR,unmanned aerial vehicle photogrammetry and other technologies have been used in subsidence monitoring,but these methods have defects due to terrain,vegetation and other images.UAV-borne LiDAR monitoring technology was used to monitor subsidence deformation in this paper.According to the geological and mining conditions of a working face in Shanxi,an observation line was established,and the settlement data of main section observation line and some checkpoints were obtained by leveling.The airborne LiDAR technology was used for monitoring,and the LiDAR point cloud data of two phases were acquired.A variety of filtering and interpolation algorithms were used to process the point cloud to obtain two phases of DEM superposition to obtain the subsidence deformation basin.By comparing and analyzing the settlement data of probability integral method prediction,UAV photogrammetry and airborne radar,accurate subsidence characteristics of mining in the whole basin are obtained.Through the above research,the following conclusions are obtained:(1)By comparing various filtering algorithms and interpolation algorithms,combined with filtering effect images,subsidence basin effect images and error statistics results,the results show that the improved incremental encrypted triangulation filter method and local polynomial interpolation algorithm are more suitable for airborne LiDAR point cloud data in the mountainous area with vegetation on the surface of the mining area.(2)The accuracy of the airborne LiDAR subsidence monitoring can reach 48 mm,which is about 50%higher than the accuracy of the mining subsidence monitoring using photo surveyor(loaded as camera)technology in the mining face.(3)The accuracy comparison between airborne LiDAR and ground observation station shows that the error in elevation is 54 mm.It can be seen that the accuracy of airborne LiDAR subsidence monitoring in small deformation area is limited,which is lower than In SAR accuracy.Therefore,airborne LiDAR technology is adopted in large deformation area and In SAR is adopted in small deformation area for feasible monitoring method in coal mining subsidence.(4)Airborne LiDAR is obvious in the spatial distribution of the measured subsidence basin complexity,in different locations in the area and the sink difference of different number of local basins,and is expected to reach more than one meter basin sink largest margin,over the expectation of LiDAR measurement precision,of which the main cause of the phenomenon appear should be overburden the complexity of structure and lithology and geomorphology.The difference between the space volume(fill)with more than expected subsidence and the space volume(excavation)with less than expected subsidence is 33% of the total subsided basin volume.The above research is of great significance for the accurate acquisition of the overall characteristics of subsidence basin,the improvement of subsidence prediction method,the reasonable design of working face layout and the protection of surface buildings in subsidence area.