Underground Morphological Detection of Ground Fissures in Collapsible Loess Area Based on Three-Dimensional Laser Scanning Technology

Abstract

Underground coal mining inevitably causes ground fissures, especially permanent cracks that cannot be closed at the boundary of the working face. Studying the underground three-dimensional morphology of the permanent cracks allows one to accurately constrain the formation and development of the ground fissures. This information will contribute to reducing mine disasters and is also a prerequisites to avoid environmental pollution. We selected the Zhangjiamao coal mine (China), which is situated in a collapsible loess area, as a case study for deciphering the formation of permanent cracks. After injecting gypsum slurry into the mine, a three-dimensional model of the ground fissures is obtained by three-dimensional (3D) laser scanner technology that records the 3D underground morphology. Integrating the geological context of a collapsible loess area, the characteristics and main processes of the ground fissure development are constrained: (1) The width of the ground fissure decreases to 0 with increasing depth and is strongly affected by the soil composition. (2) Along the vertical extension direction, the ground fissures are generally inclined to the inner-side of the working face, but the direction remains uncertain at different depths. (3) The transverse propagation direction of the ground fissure becomes more complex with increasing depth. (4) Under the influence of soil texture and water, loose soil fills the bottom of the ground fissure, thus affecting the underground 3D morphology.

Features extraction of point clouds based on Otsu’s algorithm

“…, N) as an example, a neighborhood algorithm is used to establish the topological relationship between the current point q x and its neighboring points q xr . For the neighborhood of each point, the covariance matrix C is constructed as shown in equation (1). Upon solving for the eigenvalues of C, denoted as λ 0 , λ 1 , λ 2 , and assuming λ 0 < λ 1 < λ 2 , the curvature ρ of the point cloud is calculated as shown in equation ( 2) [23]…”

“…The three-dimensional laser scanning technology has achieved substantial application in various fields due to its operational simplicity, rapid data acquisition capabilities, and high accuracy [1][2][3]. It utilizes the principle of laser ranging to represent the surface information of the target object in the form of a 3D point cloud, which generally includes the three-dimensional spatial coordinates of the object's surface, reflectivity information, and texture information, etc [4].…”

Polyurethane Exothermic Polymerization and Phase Change Material Thermal Delay Matching: An Approach to Reducing Fire Risks in Mining Polymer Materials

“…With the increase of coal mining depth, the formation of high-risk areas and fissure zones in coal mines is increasing, which seriously affects the safety of coal mine production. − Conventional inorganic filling materials tend to dilute under the influence of sudden water and they are also difficult to set. − Polyurethane (PU) filling materials are typically used in coal mines for filling protection and ensuring the safety of supports because they have the benefits of huge foaming volume, quick foaming speed, and strong pressure resistance.…”

Research on the Applicability of DInSAR, Stacking-InSAR and SBAS-InSAR for Mining Region Subsidence Detection in the Datong Coalfield

“…DIn-SAR, as an emerging Earth observation method, can measure surface deformation induced by underground mining activities with large spatial coverage, low cost, high accuracy, and all-weather observation capabilities [18]. It helps to locate and monitor underground mining subsidence in a wide area with low cost and high efficiency that conventional geophysical techniques, such as leveling [19], three-dimensional laser scanning [20], and the global navigation satellite system (GNSS) [21], are unlikely to do that [22]. However, the application of conventional DInSAR is mainly limited by spatiotemporal incoherence and atmospheric phase screening [23][24][25].…”