Under external disturbances,the shear mechanical responses and debonding failure mechanisms at anisotropic interfaces of anchoring system composed of multiphase media are inherently difficult to characterize due to th...Under external disturbances,the shear mechanical responses and debonding failure mechanisms at anisotropic interfaces of anchoring system composed of multiphase media are inherently difficult to characterize due to the concealment nature of interfacial interactions.This study establishes an equivalent shear model for a bolt-resin-rock anchoring system and conducts direct shear tests under dynamic normal load(DNL)boundary from both laboratory experiments and discrete element method(DEM)simulations.The research investigates the influence of normal dynamic load amplitude(An)and rock type on shear strength parameters,elucidating the evolutionary characteristics and underlying mechanisms of shear load and normal displacement fluctuations induced by cyclic normal loading,with maximum shear load decreasing by 36.81%to 46.94%as An increases from 10%to 70%when rock type varies from coal to limestone.Through analysis of strain field evolution,the critical impact of rock type on localization of shear failure surface is revealed,with systematic summarization of differentiated wear characteristics,failure modes,and key controlling factors associated with shear failure surface.Mesoscopic investigations enabled by DEM simulations uncover the nonuniform distribution of contact force chains within the material matrix and across the anisotropic interfaces under various DNL boundaries,clarify rock type dependent crack propagation pathways,and quantitatively assess the damage extent of shear failure surface,with the anisotropic interface damage factor increasing from 34.9%to 56.6%as An rises from 10%to 70%,and decreasing from 49.6%to 23.4%as rock type varies from coal to limestone.展开更多
This study investigated the mechanical responses and debonding mechanisms of a bolt-resin-rock composite anchoring sys-tem subjected to cyclic shear loading.A systematic analysis was conducted on the effects of the in...This study investigated the mechanical responses and debonding mechanisms of a bolt-resin-rock composite anchoring sys-tem subjected to cyclic shear loading.A systematic analysis was conducted on the effects of the initial normal load(Fsd),cyclic shear dis-placement amplitude(ud),frequency(f),and rock type on the shear load,normal displacement,shear wear characteristics,and strain field evolution.The experimental results showed that as Fsd increased from 7.5 to 120 kN,both the peak and residual shear loads exhibited in-creasing trends,with increments ranging from 1.98%to 35.25%and from 32.09%to 86.74%,respectively.The maximum shear load of each cycle declined over the cyclic shear cycles,with the rate of decrease slowing and stabilizing,indicating that shear wear primarily oc-curred at the initial cyclic shear stage.During cyclic shearing,the normal displacement decreased spirally with the shear displacement,im-plying continuous shear contraction.The spiral curves display sparse upwards and dense downward trends,with later cycles dominated by dynamic sliding along the pre-existing shear rupture surface,which is particularly evident in coal.The bearing capacity of the anchoring system varies with the rock type and is governed by the coal strength in coal,resin-rock bonding in sandstone#1 and sandstone#2,com-bined resin strength and resin-rock bonding in sandstone#3(sandstone#1,sandstone#2 and sandstone#3,increasing strength order),and resin strength and bolt-resin bonding in limestone.Cyclic shear loading induces anisotropic interfacial degradation,characterized by es-calating strain concentrations and predominant resin-rock interface debonding,with the damage severity modulated by the rock type.展开更多
This study investigates the shear mechanical responses and debonding failure mechanisms of anchoring systems comprising three anisotropic media and two anisotropic interfaces under controlled boundary conditions of co...This study investigates the shear mechanical responses and debonding failure mechanisms of anchoring systems comprising three anisotropic media and two anisotropic interfaces under controlled boundary conditions of constant normal load(F_(s)),constant normal stiffness(K),and shear rate(v).A systematic analysis of shear mechanical properties,the evolution of maximum principal strain field,and damage characteristics along shear failure surface is presented.Results from direct shear tests demonstrate that initial shear slip diminishes with increasing F_(s)and K,attributed to the normal constraint strengthening effect,while an increase in v enhances initial shear slip due to attenuated deformation coordination and stress transfer.As F_(s)increases from 7.5 to 120 kN,K from 0 to 12 MPa/mm,and v from 0.1 to 2 mm/min,the peak shear load increases by 210.32%and 80.16%with rising F_(s)and K,respectively,while decreases by 38.57%with increasing v.Correspondingly,the shear modulus exhibits,respectively,a 135.29%and 177.06%increase with rising F_(s)and K,and a 37.03%decrease with larger v.Initial shear dilation is identified as marking the formation of shear failure surface along anisotropic interfaces,resulting from the combined shear actions at the resin bolt interface,where resin undergoes shear by bolt surface protrusions,and the resin-rock interface,where mutual shear occurs between resin and rock.With increasing F_(s)and K and decreasing v,the location of the shear failure surface shifts from the resin-rock interface to the resin-bolt interface,accompanied by a transition in failure mode from tensile rupture of resin to shear off at the resin surface.展开更多
To enhance the scientific rigor of construction reverse logistics networks,improve the resource utilization rate of construction waste,and mitigate conflicts between corporate profitability and national sustainable de...To enhance the scientific rigor of construction reverse logistics networks,improve the resource utilization rate of construction waste,and mitigate conflicts between corporate profitability and national sustainable development,this study proposes a bi-level optimization model that integrates both global and local optimization.The proposed model incorporates a local optimization module within the framework of global optimization,thereby improving overall network coordination while further enhancing economic and environmental benefits.Analysis demonstrates that the inclusion of local optimization plays a positive role in reducing carbon emissions and alleviating environmental burdens.展开更多
To address the challenges of high input dimensionality,high computational costs,and insufficient prediction accuracy in the safety early warning process of hoisting operations,this study proposes a safety early warnin...To address the challenges of high input dimensionality,high computational costs,and insufficient prediction accuracy in the safety early warning process of hoisting operations,this study proposes a safety early warning model based on Random Forest(RF),Genetic Algorithm(GA),and Support Vector Machine(SVM).First,the RF algorithm is employed to assess the importance of indicators involved in the hoisting safety process,thereby reducing data dimensionality and improving the operational efficiency of the model.Next,the GA is used to optimize the parameters of the SVM to enhance its generalization capability.Finally,an integrated safety early warning model is constructed by combining RF and GA-optimized SVM.Experimental comparisons using randomly selected case data demonstrate that the proposed model offers significant advantages in early warning accuracy.Compared with traditional models,the classification warning accuracy improves by 11%,confirming the feasibility of the model.展开更多
基金support from the National Natural Science Foundation of China(Nos.51504247,52174092,51904290,and 52074259)the Natural Science Foundation of Jiangsu Province,China(No.BK20220157)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.2022YCPY0202)the China University of Mining and Technology(CUMT)Open Sharing Fund for Large-scale Instruments and Equipment(No.DYGX-2025-47)is gratefully acknowledged.
文摘Under external disturbances,the shear mechanical responses and debonding failure mechanisms at anisotropic interfaces of anchoring system composed of multiphase media are inherently difficult to characterize due to the concealment nature of interfacial interactions.This study establishes an equivalent shear model for a bolt-resin-rock anchoring system and conducts direct shear tests under dynamic normal load(DNL)boundary from both laboratory experiments and discrete element method(DEM)simulations.The research investigates the influence of normal dynamic load amplitude(An)and rock type on shear strength parameters,elucidating the evolutionary characteristics and underlying mechanisms of shear load and normal displacement fluctuations induced by cyclic normal loading,with maximum shear load decreasing by 36.81%to 46.94%as An increases from 10%to 70%when rock type varies from coal to limestone.Through analysis of strain field evolution,the critical impact of rock type on localization of shear failure surface is revealed,with systematic summarization of differentiated wear characteristics,failure modes,and key controlling factors associated with shear failure surface.Mesoscopic investigations enabled by DEM simulations uncover the nonuniform distribution of contact force chains within the material matrix and across the anisotropic interfaces under various DNL boundaries,clarify rock type dependent crack propagation pathways,and quantitatively assess the damage extent of shear failure surface,with the anisotropic interface damage factor increasing from 34.9%to 56.6%as An rises from 10%to 70%,and decreasing from 49.6%to 23.4%as rock type varies from coal to limestone.
基金The financial support from the National Natural Science Foundation of China(Nos.52174092,42472338,and 51904290)the Natural Science Foundation of Jiangsu Province,China(No.BK20220157)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.2022YCPY0202)the Open Fund of Key Laboratory of Safety and High-efficiency Coal Mining,Ministry of Education(Anhui University of Science and Technology)(No.JYBSYS202311)。
文摘This study investigated the mechanical responses and debonding mechanisms of a bolt-resin-rock composite anchoring sys-tem subjected to cyclic shear loading.A systematic analysis was conducted on the effects of the initial normal load(Fsd),cyclic shear dis-placement amplitude(ud),frequency(f),and rock type on the shear load,normal displacement,shear wear characteristics,and strain field evolution.The experimental results showed that as Fsd increased from 7.5 to 120 kN,both the peak and residual shear loads exhibited in-creasing trends,with increments ranging from 1.98%to 35.25%and from 32.09%to 86.74%,respectively.The maximum shear load of each cycle declined over the cyclic shear cycles,with the rate of decrease slowing and stabilizing,indicating that shear wear primarily oc-curred at the initial cyclic shear stage.During cyclic shearing,the normal displacement decreased spirally with the shear displacement,im-plying continuous shear contraction.The spiral curves display sparse upwards and dense downward trends,with later cycles dominated by dynamic sliding along the pre-existing shear rupture surface,which is particularly evident in coal.The bearing capacity of the anchoring system varies with the rock type and is governed by the coal strength in coal,resin-rock bonding in sandstone#1 and sandstone#2,com-bined resin strength and resin-rock bonding in sandstone#3(sandstone#1,sandstone#2 and sandstone#3,increasing strength order),and resin strength and bolt-resin bonding in limestone.Cyclic shear loading induces anisotropic interfacial degradation,characterized by es-calating strain concentrations and predominant resin-rock interface debonding,with the damage severity modulated by the rock type.
基金Projects(52174092,42472338,51904290)supported by the National Natural Science Foundation of ChinaProject(BK20220157)supported by the Natural Science Foundation of Jiangsu Province,ChinaProject(2022YCPY0202)supported by the Fundamental Research Funds for the Central Universities,China。
文摘This study investigates the shear mechanical responses and debonding failure mechanisms of anchoring systems comprising three anisotropic media and two anisotropic interfaces under controlled boundary conditions of constant normal load(F_(s)),constant normal stiffness(K),and shear rate(v).A systematic analysis of shear mechanical properties,the evolution of maximum principal strain field,and damage characteristics along shear failure surface is presented.Results from direct shear tests demonstrate that initial shear slip diminishes with increasing F_(s)and K,attributed to the normal constraint strengthening effect,while an increase in v enhances initial shear slip due to attenuated deformation coordination and stress transfer.As F_(s)increases from 7.5 to 120 kN,K from 0 to 12 MPa/mm,and v from 0.1 to 2 mm/min,the peak shear load increases by 210.32%and 80.16%with rising F_(s)and K,respectively,while decreases by 38.57%with increasing v.Correspondingly,the shear modulus exhibits,respectively,a 135.29%and 177.06%increase with rising F_(s)and K,and a 37.03%decrease with larger v.Initial shear dilation is identified as marking the formation of shear failure surface along anisotropic interfaces,resulting from the combined shear actions at the resin bolt interface,where resin undergoes shear by bolt surface protrusions,and the resin-rock interface,where mutual shear occurs between resin and rock.With increasing F_(s)and K and decreasing v,the location of the shear failure surface shifts from the resin-rock interface to the resin-bolt interface,accompanied by a transition in failure mode from tensile rupture of resin to shear off at the resin surface.
文摘To enhance the scientific rigor of construction reverse logistics networks,improve the resource utilization rate of construction waste,and mitigate conflicts between corporate profitability and national sustainable development,this study proposes a bi-level optimization model that integrates both global and local optimization.The proposed model incorporates a local optimization module within the framework of global optimization,thereby improving overall network coordination while further enhancing economic and environmental benefits.Analysis demonstrates that the inclusion of local optimization plays a positive role in reducing carbon emissions and alleviating environmental burdens.
文摘To address the challenges of high input dimensionality,high computational costs,and insufficient prediction accuracy in the safety early warning process of hoisting operations,this study proposes a safety early warning model based on Random Forest(RF),Genetic Algorithm(GA),and Support Vector Machine(SVM).First,the RF algorithm is employed to assess the importance of indicators involved in the hoisting safety process,thereby reducing data dimensionality and improving the operational efficiency of the model.Next,the GA is used to optimize the parameters of the SVM to enhance its generalization capability.Finally,an integrated safety early warning model is constructed by combining RF and GA-optimized SVM.Experimental comparisons using randomly selected case data demonstrate that the proposed model offers significant advantages in early warning accuracy.Compared with traditional models,the classification warning accuracy improves by 11%,confirming the feasibility of the model.
