Granulometric composition research of mine rocks as a material for backfilling the mined-out area in coal mines

Underground mining has a significant influence on ground movement, which induces serious environmental disturbances on land. Movements of the rock strata can be the cause of changes in the hydrogeological regimes of groundwater. As a result, the risk of flooding of the longwalls goaf increases. The specific phenomenon of the Ukrainian Donbas is the flooding of the underground roadway system at the result of the closure of the mines. Water saturation of rocks leads to a decrease in its strength. The result is repeated subsidence. The activation of the ground movement processes over the longwall goaf due to their flooding has not been studied enough. In this paper, for the geological conditions of thin coal seams typical for the Ukrainian Donbas, ground movement evolution caused by flooding of longwalls goaf was studied. Ansys code was used to analyze the evolution of surface displacement in different hydrogeological conditions. As a result of numerical simulation, it was found that full flooding of the longwall goaf leads to an increase in surface subsidence by 22.4%, while the length of the trough increase by 1.3%. Maximal inclination increases by 34.4%, and maximal curvature – by 74%. This contributes to a significant increase in hazards for surface infrastructure located on the edges of the subsidence trough. The control of the negative impact on surface infrastructure objects, water and agro-industrial objects can be ensured by a timely prediction of ground movement and the implementation of surface controlling methods to prevent critical surface deformations.

Section: Resultsmentioning

confidence: 99%

Numerical simulation of the surface subsidence evolution caused by the flooding of the longwall goaf during excavation of thin coal seams

Sakhno,

Petrenko

et al. 2023

“…In previous works, the influence of mine waste rock dumps on environmental components [17][18][19], the rational placement of dumps taking into account the migration of pollutants [20,21], the stability of slopes of bulk waste rock dumps [22][23][24][25], the sources of mine waste rock formation on the surface [26][27][28] have been studied. In addition, concepts and strategies for large-scale processing of mine waste rock dumps and tailings have been developed [29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Influence of waste rock dump placement on the geomechanical state of underground mine workings

Petlovanyi

Sai

Malashkevych

et al. 2023

Self Cite

This paper is devoted to assessing the influence of waste rock surface dumps on the geomechanical state of underground mine workings. The conditions of the Pivdenno-Bilozerskyi high-grade iron ore field are chosen as the research object. To study the influence of dump placement and the depth of mine working on the mass stress state on the contour of sublevel drifts, a numerical modeling methodology based on the SolidWorks software package has been developed. This methodology involves the substantiation of the elements and properties of the geomechanical model, as well as the calculation scheme. Polynomial patterns of changing stress value in the hanging wall drift sides have been determined in the depth intervals of 440–740 m depending on the distance of the dump to the geometric center of the stope chamber. It has been revealed that the degree of the waste rock dump influence on the stress state gradually decreases with depth. It has been found that the maximum degree of the waste rock dump influence is observed on the upper horizons. When the waste rock dump is located above the geometric center of the future stope chamber that the stress value on the contour of the hanging wall drift can increase up to 10% compared to the absence of a dump on the earth’s surface. The research results are important for designing stable parameters for supporting sublevel drifts in difficult conditions of occurrence of the hanging wall rocks.

“…In this technique, the former entry is artificially retained as the tailgate for the next mining panel by using pigsties, concrete blocks, paste-like backfill material, high-water packing material, and other fill materials [2]. Many coal mines of China, Poland, Russia, Ukraine use a pillarless mining [3], [4], [5], [6]. Many scientists believe that it is necessary urgent to implement and popularize the pillarless mining technology with reasonable economy and high safety (figure 1).…”

Section: Introductionmentioning

confidence: 99%

Stress environment around head entries with pillarless gobside entry retaining through numerical simulation incorporating the two type of filling wall

Sakhno

Kamenets

2022

Longwall mining is the most productive system for underground extraction of coal. Many coal mines use a pillarless mining. Reserving a gateroad for the usage of next panel mining is a popular gob-side entry retaining. Thus, the conventional entry retaining method requires an installation of filling walls. The mechanical properties of filling materials largely determine the quality of job-side entry retaining. Stress field evolution study around head entries when main roof console length increase with two variants of filling wall. Ansys code was used to analyze the stress evolution law under different mining conditions. As a result of numerical simulation, it was found that in the case of gob-side entry retaining, the localization of maximum stresses in surrounding rock is determined by the length console of the main roof, which hanging on the border with the gob, and the filling walls deformation module. Potential location of roof cutting, stress gradient and extremum stress in the main roof define the stability of entries. Main roof console length and filling material parameters control can help to the formation of a stable structure around the entry to meet the requirements of the next working face.