Detailed Recognition of Seismogenic Structures Activated during Underground Coal Mining: A Case Study from Bobrek Mine, Poland

Abstract

In rock mass disturbed by mining activity, distortions in the stress balance may lead to seismic energy being emitted in reactivated seismogenic structures. One way of increasing the imaging resolution of these seismically active structures is through relocation, which itself can be achieved using the cloud collapsing method. This method partially eliminates perturbations in the location of seismic energy sources concerning the actual positions of these sources. It enables events to be grouped into spatially ordered structures that may correspond to actual tectonic structures, such as fractures, fissures, or faults. We present the results of applying the collapsing method in mining seismology using a cloud of located events recorded during mining activity at one of the coalfaces in the Bobrek hard coal mine. The relocation procedure was applied to all the foci of events recorded during mining activity on face 3/503 between April 2009 and July 2010. In the relocated point cloud, two types of the linear structure responsible for generating events are automatically distinguished using the HDBSCAN algorithm: structures directly related to mining activity and structures associated with local tectonics. The location of the separated structures of the first type corresponds to the range of coalface 3/503 and the shafts delimiting earlier mined seams 507 and 509 located below. The isolated structures of the second type, with almost vertical orientation, are associated with existing zones of discontinuity that become seismically active as a result of mining activity. The identified structures lie near the biggest events recorded, which is evidence that these structures may correspond to real discontinuity zones.

Induced Seismicity and Detailed Fracture Mapping as Tools for Evaluating HDR Reservoir Volume

“…The distribution of sources after collapsing may reflect the real distribution of the hypocenters not affected by location error. The collapsing procedure exhibited an ability to delineate seismic structures in volcanic seismicity [2], mining seismicity [41], and induced seismicity from geothermal reservoirs [21].…”

Processing Laser Point Cloud in Fully Mechanized Mining Face Based on DGCNN

“…The national robotics engineering center of the United States can successfully draw a high-precision, three-dimensional map of underground roadways using the point cloud data obtained by a three-dimensional laser scanner and then propose an intelligent mining mode based on the three-dimensional map [4]. Using three-dimensional point cloud data to describe and draw the whole FMMF can accurately and intuitively reflect the spatial position relationship between the coal wall and fully mechanized mining equipment [5][6][7][8]. This can provide the direction information of a scraper conveyor so as to adjust the displacement of the hydraulic support in a timely manner.…”