A Full Coupled Thermal–Hydraulic–Chemical Model for Heterogeneity Rock Damage and Its Application in Predicting Water Inrush

Abstract

A coupled thermal–hydraulic–chemical (THC) model was carried out in this paper to study the influence of rock heterogeneity and the coupling effect of temperature, groundwater, and hydrochemistry on rock damage. Firstly, the hydrochemical and hydraulic erosion equations were established. The equations of the coupled THC model were established by combining the hydrochemical and hydraulic erosion equations, the flow equations, and the heat transfer equations. Weibull distribution was adopted to govern the heterogeneity of initial rock porosity distribution. Secondly, the influence of the hydrochemistry, the temperature and the initial porosity heterogeneity on porosity and fluid velocity change was studied. Then the rock damage rule changed with time at different pH values and temperature was studied. Finally, an actual deep coal mine model was established to apply the THC model to predict water inrush. Results indicate that: (1) The average porosity and average fluid velocity approximately show linear growth and exponential growth with time, respectively, and their growth rates increase with decreasing pH value and increasing temperature in a certain acidity and temperature range. (2) The increase of initial porosity heterogeneity has little influence on porosity change, but it can increase the fluid velocity growth rate. The porosity heterogeneity and fluid velocity heterogeneity approximately show exponential growth with increasing time, and the rock heterogeneity growth contributes to form cracks. The increase of temperature and decrease of pH value have little influence on the porosity heterogeneity, but they can increase the growth rate of the fluid velocity heterogeneity. (3) The rock damage shows linear growth with time, and its growth rate increases with decreasing pH value and increasing temperature in a certain acidity range and temperature range. (4) The increase of rock heterogeneity can increase the possibility of water inrush.

Study on overburden failure characteristics in deep thick loose seam and thick coal seam mining

“…The mining simulation of the working face is carried out according to the established numerical model for thick and loose thick coal seams. With reference to the measured rock mechanics parameters in the Zhaolou coal mine, the mechanical parameters of the top and bottom rock layers in the model coal seam are determined (Liu et al 2019). The simulation data of the working surface propulsion distance at 50 m, 60 m, 70 m, 80 m, 90 m, and 100 m is extracted (Goryunov et al 1993).…”

Analysis on Treatment Effect of Mine Tunnel Construction Spring in Karst Area

“…Relevant scholars [4][5][6] have carried out relevant studies on the mechanism of crack propagation in the rock mass, carried out corresponding numerical simulation analysis based on the research results, and achieved good results. e relevant results can provide an important reference for karst treatment.…”

Coupled thermal–hydraulic–mechanical–chemical modeling for permeability evolution of rocks through fracture generation and subsequent sealing

“…Although several coupled THMC models employing the damage theory include chemical phenomena between the rock mass and the fluid driven by the fracture generation [28,29], they cannot consider the important process of pressure solution. Liu et al [28] proposed a coupled THMC model taking into account the interaction between the chemical and damage componentsthe change in rock damage due to the change in the reaction rate of chemical erosion, and the change in the concentration of the fluidized solids from hydraulic and chemical erosion due to the change in the rock porosity brought about by the damage. Fan et al [29] presented a coupled THMC process for acid fracturing within rock masses by considering the chemical reactions between the minerals and the acid enhanced by the increase in reaction sites due to the fracture initiation/propagation.…”