A novel block–particle discrete-element simulation method that matches the double medium of overlying rock(OLR)and loose layer(LSL)in coal mining is developed in this study.This method achieves the collaborative fail...A novel block–particle discrete-element simulation method that matches the double medium of overlying rock(OLR)and loose layer(LSL)in coal mining is developed in this study.This method achieves the collaborative failure characteristics of mining damage under the conduction of double media between the OLR and LSL by combining the self-weight stress loading of the LSL and the breakage morphology of the bedrock top.Based on this,the conduction law of high-strength mining damage in the double medium in a western mining area is simulated and analyzed.The combining effect of the OLR breakage morphology and LSL characteristics on the surface-subsidence characteristics is analyzed and verified based on on-site measurements.The results indicate that the OLR is guided by the“double-control layer and thick-soft rock buffer layer”and shows“grouping subsidence”,whereas the surface forms collaborative subsidence with the thick-soft rock buffer layer.In the ultra-full mining stage,the surface presents an“asymmetric inverted trapezoidal”subsidence trough shape.The simulation results agree well the on-site measurements in terms of the surface-subsidence and bedrock-subsidence coefficients.The proposed simulation method provides a scientific approach for investigating the micro-conduction mechanism of mining damage under the effect of high-strength mining in western mining areas.It will benefit future investigations pertaining to the characteristics of OLR breakage and surface subsidence under conditions such as LSL thickness and proportion.展开更多
In this paper,according to the migration and diffusion law of MICP solution in fracture-pore medium,the migration and diffusion equation of MICP solution in loess fracture-pore medium was derived first.Then,the migrat...In this paper,according to the migration and diffusion law of MICP solution in fracture-pore medium,the migration and diffusion equation of MICP solution in loess fracture-pore medium was derived first.Then,the migration and diffusion test was carried out by using the self-made Mdevice.In the model,the apertures of the fracture of 0.5 mm,1.0 mm and 1.5 mm were selected,and the calcium ion concentrations at different points were measured by atomic absorption method,to obtain the distribution map of calcium ion concentration.According to the test results,the migration speed of calcium ions in the direction along the fracture is less than the diffusion speed of the wet peak,and the vertical fracture direction is faster than the diffusion speed of the wet peak.The distribution range of calcium ion concentration increases first and then decreases with the increase in fracture opening.COMSOL was used to compile the mathematical equation,and the whole process of MICP solution migration and diffusion was numerically simulated.The numerical calculation results are basically consistent with the experimental results,and the derived mathematical equation is reasonable.展开更多
基金support for this work is provided by the National Key R&D Program of China(2023YFC3012101)the National Natural Science Foundation of China(52474161)the Fundamental Research Funds for the Central Universities(2024ZKPYNY01).
文摘A novel block–particle discrete-element simulation method that matches the double medium of overlying rock(OLR)and loose layer(LSL)in coal mining is developed in this study.This method achieves the collaborative failure characteristics of mining damage under the conduction of double media between the OLR and LSL by combining the self-weight stress loading of the LSL and the breakage morphology of the bedrock top.Based on this,the conduction law of high-strength mining damage in the double medium in a western mining area is simulated and analyzed.The combining effect of the OLR breakage morphology and LSL characteristics on the surface-subsidence characteristics is analyzed and verified based on on-site measurements.The results indicate that the OLR is guided by the“double-control layer and thick-soft rock buffer layer”and shows“grouping subsidence”,whereas the surface forms collaborative subsidence with the thick-soft rock buffer layer.In the ultra-full mining stage,the surface presents an“asymmetric inverted trapezoidal”subsidence trough shape.The simulation results agree well the on-site measurements in terms of the surface-subsidence and bedrock-subsidence coefficients.The proposed simulation method provides a scientific approach for investigating the micro-conduction mechanism of mining damage under the effect of high-strength mining in western mining areas.It will benefit future investigations pertaining to the characteristics of OLR breakage and surface subsidence under conditions such as LSL thickness and proportion.
基金support from the Shaanxi Natural Science Basic Research Project(Grant no.2020JM-483)Investigation on the Interfacial Bonding Mechanism of Microbial Mineralization Repair Grout for Cracks in Rammed Earth Heritage(Grant no.2025JC-YBMS-551)the National Natural Science Foundation of China(NSFC)(Grant no.51408464).
文摘In this paper,according to the migration and diffusion law of MICP solution in fracture-pore medium,the migration and diffusion equation of MICP solution in loess fracture-pore medium was derived first.Then,the migration and diffusion test was carried out by using the self-made Mdevice.In the model,the apertures of the fracture of 0.5 mm,1.0 mm and 1.5 mm were selected,and the calcium ion concentrations at different points were measured by atomic absorption method,to obtain the distribution map of calcium ion concentration.According to the test results,the migration speed of calcium ions in the direction along the fracture is less than the diffusion speed of the wet peak,and the vertical fracture direction is faster than the diffusion speed of the wet peak.The distribution range of calcium ion concentration increases first and then decreases with the increase in fracture opening.COMSOL was used to compile the mathematical equation,and the whole process of MICP solution migration and diffusion was numerically simulated.The numerical calculation results are basically consistent with the experimental results,and the derived mathematical equation is reasonable.
