The Development of Dewatering Predictions of the Velenje Coalmine

Abstract

Abstract:The complex hydro-geological situation, particularly in terms of groundwater, has been a constant threat to the mining carried out at the Velenje colliery since its inception. Of particular interest to the authors are the difficulties presented to the colliery by the adjacent sand aquifers, as the water pressure within these sands directly impacts mining safety, and the aquifers themselves are most directly affected by dewatering. In order to monitor water levels and estimate dewatering at the Velenje wells, multi-layered modelling using 3D Finite Difference Method (FDM) has already been carried out. However, FDM is not optimal due to its greater dependence on cell size than on water flow. In 2017 in Velenje, a series of wells will be terminated as a result of mining and mining-induced subsidence, leading to dewatering and danger of flooding. As part of a plan to address this by replacing dewatering structures, a series of drive-in filters will be implemented around the entry and exit point tunnels of a longwall face. Because FDM seems to be inadequate for purposes of optimising this process, the Finite Elements Method (FEM) was applied in this case. Based on such an application of FEM, a prediction of the optimisation of drive-in filters was carried out by the authors.

A Novel Caving Model of Overburden Strata Movement Induced by Coal Mining

“…Additionally, the most significant changes of hydraulic properties occur during the period of maximum subsidence. Increases of one or two orders of magnitude in permeability and a moderate increase in storativity from before and after subsidence are often reported, along with typical increases of an order of magnitude in the inner subsidence and two in the marginal tensional zone [5,6,46].…”

“…As the shields (hydraulic supports) move, the mine roof behind them continues to cantilever and caves into the mine void, which experiences the process of elastic deformation, plastic deformation, and failure [16,20], producing two types of tensile fractures at the surface over the panel: static tensile fracture above the side of a panel and dynamic tensile fractures that follow behind the advancing face [16,17]. The dynamic tensile fractures close as a result of compressional stress after the advance of the face, and static tensile fractures remain open for several months after mining [17], Currently, a variety of methods, ranging from analytical methods and field experiments to numerical and physical simulation, have been used that mainly focus on the mining-induced effects on the movement of overburden strata, the generation of fractures, and subsidence [2,13,29,30,[45][46][47]. However, very few detailed studies of the caving mechanism of overburden strata have been reported.…”

“…The redistribution of the overburden stress regime caused by longwall mining brings about general increases in fracture porosity and permeability owing to the development of fractures, joints, and bedding separations, resulting in the disruption of the natural groundwater flow system to a great extent [12,15,16,44]. Currently, a variety of methods, ranging from analytical methods and field experiments to numerical and physical simulation, have been used that mainly focus on the mining-induced effects on the movement of overburden strata, the generation of fractures, and subsidence [2,13,29,30,[45][46][47]. However, very few detailed studies of the caving mechanism of overburden strata have been reported.…”

Thermal conductivity of rocks and geothermal water

“…We are interested in how long the water will retain the constant temperature without any impact of the cold return water inflow (random data) [4][5][6][7]: Volume-specific heat capacity of the deposit is derived as follows:…”

Finite-Difference Numerical Simulation of Dewatering System in a Large Deep Foundation Pit at Taunsa Barrage, Pakistan

“…Wang et al [23] applied a three-dimensional finite-difference forward analysis approach to verify the feasibility of a dewatering scheme for a large deep foundation pit. In further studies, researchers used different techniques for dewatering of foundation pits in various regions of the world [24][25][26][27][28][29][30][31].…”