Both bulk stress(σ_(i i))and stress path(SP)significantly affect the transportation characteristics of deep gas during reservoir pressure depletion.Therefore,the experimental study of horizontal stress unloading on s...Both bulk stress(σ_(i i))and stress path(SP)significantly affect the transportation characteristics of deep gas during reservoir pressure depletion.Therefore,the experimental study of horizontal stress unloading on seepage behavior of gas-bearing coal under constantσi i-constraints is performed.The results show that coal permeability is affected by horizontal stress anisotropy(σ_(H)≠σh),and the contribution of minor horizontal stress to permeability is related to the differential response of horizontal strain.The slippage phenomenon is prominent in deep high-stress regime,especially in low reservoir pressure.σ_(i i)and SP jointly determine the manifestation of slippage effect and the strength of stress sensitivity(γ)of permeability.Deep reservoir implies an incremental percentage of slip-based permeability,and SP weakens the slippage effect by changing the elastic–plastic state of coal.However,γis negatively correlated with slippage effect.From the Walsh model,narrow(low aspect-ratio)fractures within the coal under unloading SP became the main channel for gas seepage,and bring the effective stress coefficient of permeability(χ)less than 1 for both low-stress elastic and high-stress damaged coal.With the raise of the effective stress,the effect of pore-lined clay particles on permeability was enhanced,inducing an increase inχfor highstress elastic coal.展开更多
To investigate the deterioration of mechanical properties in engineering rock masses subjected to fatigue stress,this study conducted laboratory tests, theoretical analysis, and model building to analyze the evolution...To investigate the deterioration of mechanical properties in engineering rock masses subjected to fatigue stress,this study conducted laboratory tests, theoretical analysis, and model building to analyze the evolution of mechanical and rockburst characteristics in gypsum-like rock before and after fatigue loading. The results showedthat the effects of cyclic stress and loading frequency on fatigue damage characteristics of the samples areinterrelated. The effect of fatigue cyclic stress on the mechanical parameters and rockburst parameters of thesamples after fatigue loading is relatively straightforward, while the impact of frequency on the mechanicalproperties of samples after fatigue loading is more complex. The impact of frequency on mechanical propertiesand rockburst parameters varies distinctly under different cyclic stress conditions. A deterioration index model(λ=p+jq) was established for the samples after fatigue loading, and the real part, imaginary part, and jλj of themodel were calculated to plot the function in the complex plane. This model provided insight into the evolution ofmechanical properties and rockburst characteristics in gypsum-like rock before and after fatigue loading withdifferent stress levels and frequencies. By examining the λ curve’s position within the complex plane, the overallvariation in mechanical properties was assessed. Finally, neural network methods were employed to extend andtest the complex plane model, expanding the input factors from discrete data points to continuous definition fieldson the number line, thereby increasing the model's practicality and applicability.展开更多
In this study, we systematically studied the occurrence regularity of in situ stress in the Pingdingshan mine. The critical criterion model of coal-rock destabilization was established based on the theoretical framewo...In this study, we systematically studied the occurrence regularity of in situ stress in the Pingdingshan mine. The critical criterion model of coal-rock destabilization was established based on the theoretical framework of fracture mechanics. Furthermore, we analyzed the coupling destabilization mechanism of in situ stress and gas and studied the influence of the variation between original rock stress and mining-induced stress on the critical criterion. Through field experiments and applications, we established a three-dimensional gas drainage technology system for areas with a large mining height and long work face. Based on our research, a demonstration project was developed for deep mine dynamic disaster control. The technical system included the arrangement and optimization of pre-drainage holes along the coal seam, technology, and optimization of gas drainage through the bottom drainage tunnel and upper corner, gas drainage technology through sieve tubes, and a two plugging with one injection under pressure sealing technology. The implementation of the demonstration project effectively reduced the gas content and pressure of the coal seam in the deep mine, and the project increased the critical strength of the instability and failure of coal and rock.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52304265,52174216,and 52274145)the Natural Science Foundation of Jiangsu Province(No.BK20221121)the State Key Laboratory of Mining Disaster Prevention and Control(Shandong University of Science and Technology)and Ministry of Education(No.JMDPC202301)。
文摘Both bulk stress(σ_(i i))and stress path(SP)significantly affect the transportation characteristics of deep gas during reservoir pressure depletion.Therefore,the experimental study of horizontal stress unloading on seepage behavior of gas-bearing coal under constantσi i-constraints is performed.The results show that coal permeability is affected by horizontal stress anisotropy(σ_(H)≠σh),and the contribution of minor horizontal stress to permeability is related to the differential response of horizontal strain.The slippage phenomenon is prominent in deep high-stress regime,especially in low reservoir pressure.σ_(i i)and SP jointly determine the manifestation of slippage effect and the strength of stress sensitivity(γ)of permeability.Deep reservoir implies an incremental percentage of slip-based permeability,and SP weakens the slippage effect by changing the elastic–plastic state of coal.However,γis negatively correlated with slippage effect.From the Walsh model,narrow(low aspect-ratio)fractures within the coal under unloading SP became the main channel for gas seepage,and bring the effective stress coefficient of permeability(χ)less than 1 for both low-stress elastic and high-stress damaged coal.With the raise of the effective stress,the effect of pore-lined clay particles on permeability was enhanced,inducing an increase inχfor highstress elastic coal.
基金supported by Scientific Research Foundation of State Key Lab of Coal Mine Disaster Dynamics and Control(Project Approval Number:2011DA105287-zd201804)National Natural Science Foundation of China(No.51974104)。
文摘To investigate the deterioration of mechanical properties in engineering rock masses subjected to fatigue stress,this study conducted laboratory tests, theoretical analysis, and model building to analyze the evolution of mechanical and rockburst characteristics in gypsum-like rock before and after fatigue loading. The results showedthat the effects of cyclic stress and loading frequency on fatigue damage characteristics of the samples areinterrelated. The effect of fatigue cyclic stress on the mechanical parameters and rockburst parameters of thesamples after fatigue loading is relatively straightforward, while the impact of frequency on the mechanicalproperties of samples after fatigue loading is more complex. The impact of frequency on mechanical propertiesand rockburst parameters varies distinctly under different cyclic stress conditions. A deterioration index model(λ=p+jq) was established for the samples after fatigue loading, and the real part, imaginary part, and jλj of themodel were calculated to plot the function in the complex plane. This model provided insight into the evolution ofmechanical properties and rockburst characteristics in gypsum-like rock before and after fatigue loading withdifferent stress levels and frequencies. By examining the λ curve’s position within the complex plane, the overallvariation in mechanical properties was assessed. Finally, neural network methods were employed to extend andtest the complex plane model, expanding the input factors from discrete data points to continuous definition fieldson the number line, thereby increasing the model's practicality and applicability.
基金the National Natural Science Foundation of China(Grant No.51874053)the Scientific Research Foundation of State Key Laboratory of Coal Mine Disaster Dynamics and Control(No.2011DA105287-zd201804).
文摘In this study, we systematically studied the occurrence regularity of in situ stress in the Pingdingshan mine. The critical criterion model of coal-rock destabilization was established based on the theoretical framework of fracture mechanics. Furthermore, we analyzed the coupling destabilization mechanism of in situ stress and gas and studied the influence of the variation between original rock stress and mining-induced stress on the critical criterion. Through field experiments and applications, we established a three-dimensional gas drainage technology system for areas with a large mining height and long work face. Based on our research, a demonstration project was developed for deep mine dynamic disaster control. The technical system included the arrangement and optimization of pre-drainage holes along the coal seam, technology, and optimization of gas drainage through the bottom drainage tunnel and upper corner, gas drainage technology through sieve tubes, and a two plugging with one injection under pressure sealing technology. The implementation of the demonstration project effectively reduced the gas content and pressure of the coal seam in the deep mine, and the project increased the critical strength of the instability and failure of coal and rock.
