Accurate prediction of rockburst intensity levels is crucial for ensuring the safety of deep hard rock engineering construction.This paper introduced an expert system for rockburst intensity level prediction that empl...Accurate prediction of rockburst intensity levels is crucial for ensuring the safety of deep hard rock engineering construction.This paper introduced an expert system for rockburst intensity level prediction that employs machine learning algorithms as the basis for its inference rules.The system comprises four modules:a database,a repository,an inference engine,and an interpreter.A database containing 1114 rockburst cases was used to construct 357 datasets that serve as the repository for the expert system.Additionally,19 types of machine learning algorithms were used to establish 6783 micro-models to construct cognitive rules within the inference engine.By integrating probability theory and marginal analysis,a fuzzy scoring method based on the SoftMax function was developed and applied to the interpreter for rockburst intensity level prediction,effectively restoring the continuity of rockburst characteristics.The research results indicate that ensemble algorithms based on decision trees are more effective in capturing the characteristics of rockburst.Key factors for accurate prediction of rockburst intensity include uniaxial compressive strength,elastic energy index,the maximum principal stress,tangential stress,and their composite indicators.The accuracy of the proposed rockburst intensity level prediction expert system was verified using 20 engineering rockburst cases,with predictions aligning closely with the actual rockburst intensity levels.展开更多
椎间盘由髓核、纤维环和软骨终板组成,对维持脊柱正常生理功能至关重要。椎间盘退变(intervertebral disc degeneration,IDD)是导致腰背痛等脊柱退行性疾病的主要病理基础,给人们的健康状况造成极大的困扰。然而目前对IDD的分子机制仍...椎间盘由髓核、纤维环和软骨终板组成,对维持脊柱正常生理功能至关重要。椎间盘退变(intervertebral disc degeneration,IDD)是导致腰背痛等脊柱退行性疾病的主要病理基础,给人们的健康状况造成极大的困扰。然而目前对IDD的分子机制仍然缺乏清晰的了解,导致缺乏有效的靶向干预措施。RAS同源家族成员A(RAS homolog family member A,RhoA)/Rho相关蛋白激酶(Rho-associated protein kinase,ROCK)信号通路是调节细胞收缩、迁移和生长的经典通路。其被激活后可参与调控细胞骨架重塑、细胞外基质代谢、生物钟节律、细胞表型改变、细胞衰老及死亡等环节,进而影响IDD的病理进程。深入探究RhoA/ROCK信号通路在IDD中的作用,不仅能揭示疾病发生的分子生物学机制,也有望为研发靶向该通路的治疗策略提供理论依据。展开更多
The development of metallic mineral resources generates a significant amount of solid waste,such as tailings and waste rock.Cemented tailings and waste-rock backfill(CTWB)is an effective method for managing and dispos...The development of metallic mineral resources generates a significant amount of solid waste,such as tailings and waste rock.Cemented tailings and waste-rock backfill(CTWB)is an effective method for managing and disposing of this mining waste.This study employs a macro-meso-micro testing method to investigate the effects of the waste rock grading index(WGI)and loading rate(LR)on the uniaxial compressive strength(UCS),pore structure,and micromorphology of CTWB materials.Pore structures were analyzed using scanning electron microscopy(SEM)and mercury intrusion porosimetry(MIP).The particles(pores)and cracks analysis system(PCAS)software was used to quantitatively characterize the multi-scale micropores in the SEM images.The key findings indicate that the macroscopic results(UCS)of CTWB materials correspond to the microscopic results(pore structure and micromorphology).Changes in porosity largely depend on the conditions of waste rock grading index and loading rate.The inclusion of waste rock initially increases and then decreases the UCS,while porosity first decreases and then increases,with a critical waste rock grading index of 0.6.As the loading rate increases,UCS initially rises and then falls,while porosity gradually increases.Based on MIP and SEM results,at waste rock grading index 0.6,the most probable pore diameters,total pore area(TPA),pore number(PN),maximum pore area(MPA),and area probability distribution index(APDI)are minimized,while average pore form factor(APF)and fractal dimension of pore porosity distribution(FDPD)are maximized,indicating the most compact pore structure.At a loading rate of 12.0 mm/min,the most probable pore diameters,TPA,PN,MPA,APF,and APDI reach their maximum values,while FDPD reaches its minimum value.Finally,the mechanism of CTWB materials during compression is analyzed,based on the quantitative results of UCS and porosity.The research findings play a crucial role in ensuring the successful application of CTWB materials in deep metal mines.展开更多
This study analyzed the interaction between sequentially installed combined support systems and the surrounding rock.Six distinct forms of elastic-brittle-plastic rock masses with reinforcement were analyzed,along wit...This study analyzed the interaction between sequentially installed combined support systems and the surrounding rock.Six distinct forms of elastic-brittle-plastic rock masses with reinforcement were analyzed,along with the critical displacements that governed their transition behaviors.Virtual support pressure was introduced to assess the spatial influence of the tunnel face.It was determined by integrating the longitudinal displacement profile with the proposed ground characteristic curve solutions under various ground conditions.Considering the timing of support installation,the support-rock interaction was divided into three phases.A method was presented to determine the evolution of this interaction based on critical displacements.An analytical approach was further proposed to describe the complete process of support system-rock interaction using displacement coordination.The analytical results are validated against numerical simulations and field measurements,and the method's advantages are demonstrated through comparisons with existing models and the convergence-confinement approach.Finally,the effects of surrounding rock and support parameters are examined.The results indicate that residual cohesion,the friction angle of reinforced ground,and reinforcement thickness strongly influence tunnel behavior.Additionally,increasing the stiffness or advancing the installation of secondary support substantially raises secondary support pressure.展开更多
To investigate the long-term stability of soft-hard interbedded rock masses with initial damage induced by earthquakes and periodic drying and wetting,this study prepared samples with different initial damage through ...To investigate the long-term stability of soft-hard interbedded rock masses with initial damage induced by earthquakes and periodic drying and wetting,this study prepared samples with different initial damage through cyclic loading and unloading(CLU)experiments followed by cyclic drying and wetting(CDW)experiments,and finally conducted creep experiments.The study analyzed the effects of initial damage on creep mechanical behavior,crack evolution,and explored failure precursor information,revealing the damage failure mechanisms.The results show that the structural characteristics of the rock mass control its macroscopic failure mode.Initial damage promotes microcrack development,influences the fracture mode,and increases the proportion of high-frequency(200−280 kHz)acoustic emission events during creep.Meanwhile,initial damage exacerbates creep characteristics,increasing the creep rate,shortening total creep failure time,and reducing long-term strength.The damage failure is attributed to:the generation of internal cracks and pores in the rock caused by CLU;mineral hydrolysis and expansion-contraction due to CDW,resulting in weakened intergranular cementation;and full development of cracks and pores under creep stress.Additionally,the deformation difference coefficient and the coefficient of variation of RA/AF values can serve as precursor indicators for creep failure.展开更多
Aiming at the problem of dynamic instability of hard-brittle jointed rock surrounding in deep tunnel/roadway engineering,combining with the support concepts of"coupling rigidity with flexibility"and"ove...Aiming at the problem of dynamic instability of hard-brittle jointed rock surrounding in deep tunnel/roadway engineering,combining with the support concepts of"coupling rigidity with flexibility"and"overcoming rigidity by flexibility",the prevention and control method with"rigid-flexible coupling(R-F-C)"was put forward.Through numerical simulation calculation,the impact damage process,acoustic emission(AE)evolution characteristics,and element stress/displacement evolution characteristics of unsupported surrounding rock structure model,rigid supporting surrounding rock structure model,and"R-F-C"supporting surrounding rock structure model under horizontal bidirectional impact loading were compared and analyzed.Based on the theory of stress wave propagation,the dynamic instability catastrophe mechanism of three kinds of supporting structure models induced by horizontal bidirectional impact loading was revealed.Based on the Mohr-Coulomb strength theory,the stress discrimination methods of dynamic catastrophe of surrounding rock induced by horizontal bidirectional impact loading under three kinds of supporting structures were proposed.Combined with the above numerical simulation study,the explosion impact physical and mechanical test of"R-F-C"surrounding rock supporting plate structure was further designed and carried out.Finally,combined with the"conceptual model of ball-cliff potential energy instability",the energy driving theory and energy transformation mechanism of impact-induced rockburst under three kinds of supporting structures were discussed deeply.The research results provided a scientific basis for further promoting the effective application of"R-F-C"supporting structure in the prevention and control of dynamic instability of deep tunnel/roadway surrounding rock.展开更多
The stability of the roof in coal mining is crucial for ensuring safe extraction.Studying the mechanical behavior of rock beams under various conditions is essential for improving coal mining safety.However,research o...The stability of the roof in coal mining is crucial for ensuring safe extraction.Studying the mechanical behavior of rock beams under various conditions is essential for improving coal mining safety.However,research on the dynamic response of rock beams under sudden unloading remains limited.This study utilized a self-developed bidirectional loading and unilateral unloading test system to simulate how sudden lower strata subsidence induces the fracture of upper hard rock beams.Bottom unloading experiments were performed on rock beams with varying thicknesses and spans.The experiments recorded surface crack development and internal damage evolution using high speed photography and acoustic emission monitoring.The results show that rock beams experience multiple stress reductions after unloading,with the largest reduction occurring in the first stage.Flexural deformation was observed,becoming more pronounced as the thickness-span ratio decreased.Greater thickness increased shear cracks and crack expansion angles,while larger spans promoted tensile cracks,arched crack formation,and notable rock spalling.Acoustic emission analysis showed that signal count and energy increased with thickness and span.Finally,discrete element numerical simulations revealed the critical controlling role of harder rock strata in rock beam failure:when the harder strata are at the top,cracks are sharp,and shear failure is more likely;when they are at the bottom,the overall failure range expands,and cracks tend to form arches.These findings improve the understanding of dynamic rock beam fracture under sudden unloading and offer theoretical guidance for roof stability control in deep mining.展开更多
To review the rockburst proneness(or tendency)criteria of rock materials and compare the judgment accuracy of them,twenty criteria were summarized,and their judgment accuracy was evaluated and compared based on the la...To review the rockburst proneness(or tendency)criteria of rock materials and compare the judgment accuracy of them,twenty criteria were summarized,and their judgment accuracy was evaluated and compared based on the laboratory tests on fourteen types of rocks.This study begins firstly by introducing the twenty rockburst proneness criteria,and their origins,definitions,calculation methods and grading standards were summarized in detail.Subsequently,to evaluate and compare the judgment accuracy of the twenty criteria,a series of laboratory tests were carried out on fourteen types of rocks,and the rockburst proneness judgment results of the twenty criteria for the fourteen types of rocks were obtained accordingly.Moreover,to provide a unified basis for the judgment accuracy evaluation of above criteria,a classification standard(obtained according to the actual failure results and phenomena of rock specimen)of rockburst proneness in laboratory tests was introduced.The judgment results of the twenty criteria were compared with the judgment results of this classification standard.The results show that the judgment results of the criterion based on residual elastic energy(REE)index are completely consistent with the actual rockburst proneness,and the other criteria have some inconsistent situations more or less.Moreover,the REE index is based on the linear energy storage law and defined in form of a difference value and considered the whole failure process,and these superior characteristics ensure its accuracy.It is believed that the criterion based on REE index is comparatively more accurate and scientific than other criteria,and it can be recommended to be applied to judge the rockburst proneness of rock materials.展开更多
目的探究毛兰素(Erianin)在特应性皮炎(atopic dermatitis,AD)中的作用及其在高迁移率族蛋白1(high mobility group box-1,HMGB1)/晚期糖基化终末产物受体(receptor for advanced glycation end products,RAGE)-Ras同源基因家族成员A(Ra...目的探究毛兰素(Erianin)在特应性皮炎(atopic dermatitis,AD)中的作用及其在高迁移率族蛋白1(high mobility group box-1,HMGB1)/晚期糖基化终末产物受体(receptor for advanced glycation end products,RAGE)-Ras同源基因家族成员A(Ras homolog gene family member A,RhoA)/Rho关联含卷曲螺旋结合蛋白激酶1(recombinant Rho associated coiled coil containing protein kinase 1,ROCK1)信号通路中的调控机制。方法1-氯-2,4-二硝基苯(1-Chloro-2,4-dinitrobenzene,DNCB)诱导BALB/c小鼠作为AD的模型,测量小鼠的皮肤厚度、脾和淋巴结的重量。甲苯胺蓝和HE染色检测小鼠的背部皮肤和耳朵的病理改变;ELISA检测炎症因子水平;肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)刺激HaCaT细胞建立AD体外模型;采用流式细胞术检测细胞活性氧(reactive oxygen species,ROS);免疫荧光法检测线粒体活性氧(mitochondrion reactive oxygen species,mtROS);TUNEL检测细胞凋亡情况;免疫蛋白印迹法检测HMGB1、RAGE、RhoA、ROCK1蛋白表达情况。结果在体内实验中毛兰素抑制皮肤厚度的增加,减轻脾和淋巴结重量,改善炎症细胞的浸润和肥大细胞脱颗粒,降低炎症因子水平(P<0.05)。在体外实验中,毛兰素减少TNF-α诱导的HaCaT细胞ROS、mtROS的产生(P<0.01)。毛兰素治疗后HMGB1、RAGE、RhoA及ROCK1的蛋白表达量下降(P<0.01);使用RAGE特异性阻断剂(TFA)处理r-HMGB1刺激的HaCaT细胞后,HMGB1的表达没有发生变化,RAGE、RhoA及ROCK1表达减少(P<0.01);在Rho激酶抑制剂Y-27632+r-HMGB1组中,除RAGE的表达没有降低,其余结果与TFA+r-HMGB1组相近。结论毛兰素可能通过调节HMGB1/RAGE-RhoA/ROCK1信号通路缓解特应性皮炎。展开更多
Composite rock layers are widely present in mining and tunnel construction projects,and are prone to dynamic tensile failure along bedding planes under dynamic disturbances.To ensure engineering safety,it is necessary...Composite rock layers are widely present in mining and tunnel construction projects,and are prone to dynamic tensile failure along bedding planes under dynamic disturbances.To ensure engineering safety,it is necessary to conduct research on the dynamic tensile characteristics under different working conditions.Considering the difficulty of on-site sampling,composite rock samples were prepared with cement mortar,and dynamic Brazilian splitting tests were carried out using split Hopkinson pressure bar(SHPB)equipment,a high-speed camera,and PFC^(2D)numerical software to explore their dynamic tensile properties under dynamic disturbance under different strength ratios and other factors.The results show that the dynamic tensile strength of samples exhibits a rising trend with the strength ratio and strain rate growth.As the incident angle increases from 0°to 90°,the stress contour deflects transform from center-splitting failure to tension-shear combined failure and back again.The influence of the incident order in different lithology rocks on the dynamic tensile strength of composite samples is controlled by strain rate,and when the strain rate increases to 400 s^(-1),the difference in strength due to the sequence of incident stress waves is within 5%.Based on PFC^(2D),the strength ratio of composite samples has a certain influence on the distribution of microfractures.With strength ratios equaling 1.5 or 2.0,the cracks are mainly concentrated on the softer material side,while a large number of cracks are distributed on both sides of the bedding plane with a strength ratio equal to 1.2.展开更多
The shear performance of bolts plays a crucial role in controlling rock mass stability,and the roughness of the joint surface is one of the main factors affecting the mechanical properties of anchored joints.The 2nd g...The shear performance of bolts plays a crucial role in controlling rock mass stability,and the roughness of the joint surface is one of the main factors affecting the mechanical properties of anchored joints.The 2nd generation of negative Poisson ratio(2G-NPR)bolt is a new independently developed material characterized by high strength and toughness.However,the influence of joint surface roughness on its anchorage shear performance remains unexplored.This study involves preparing regular saw-tooth jointed rock masses and conducting laboratory shear comparison tests on unbolted samples,2G-NPR bolts,and Q235 steel anchors.A three-dimensional finite element method,developed by the author,was employed for numerical simulations to analyze the influence of saw-tooth angles on the shear resistance of anchored bolts.The findings show that the anchorage of bolts enhances the shear strength and deformation of saw-tooth rock joints.The 2G-NPR bolts demonstrate superior performance in shear strength and deformation enhancement compared to Q235 steel anchors,including improved toughening and crack-arresting effects.Furthermore,the improvement of the shear strength and displacement of the bolt decreases with the increase of the joint saw-tooth angle.These findings provide a valuable test basis for the engineering application of 2G-NPR bolts in rock mass stabilization.展开更多
In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefo...In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefore,in this study,based on the stepped failure mode of bedding jointed rock slopes,considering the influence of the upper rock mass on the lower stepped sliding mass,the improved failure model for analyzing the interaction force(F_(AB))between two regions is constructed,and the safety factors(F_(S))of two regions and whole region are derived.In addition,this paper proposes a method to determine the existence of F_(AB) using their respective acceleration values(a_(A) and a_(B))when regions A and B are unstable.The influences of key parameters on two regions and the whole region are analyzed.The results show that the variation of the F_(AB) and F_(S) of two regions can be obtained accurately based on the improved failure model.The accuracy of the improved failure model is verified by comparative analysis.The research results can explain the interaction mechanism of two regions and the natural phenomenon of slope failure caused by the development of cracks.展开更多
基金Project(42077244)supported by the National Natural Science Foundation of ChinaProject(2020-05)supported by the Open Research Fund of Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization,China。
文摘Accurate prediction of rockburst intensity levels is crucial for ensuring the safety of deep hard rock engineering construction.This paper introduced an expert system for rockburst intensity level prediction that employs machine learning algorithms as the basis for its inference rules.The system comprises four modules:a database,a repository,an inference engine,and an interpreter.A database containing 1114 rockburst cases was used to construct 357 datasets that serve as the repository for the expert system.Additionally,19 types of machine learning algorithms were used to establish 6783 micro-models to construct cognitive rules within the inference engine.By integrating probability theory and marginal analysis,a fuzzy scoring method based on the SoftMax function was developed and applied to the interpreter for rockburst intensity level prediction,effectively restoring the continuity of rockburst characteristics.The research results indicate that ensemble algorithms based on decision trees are more effective in capturing the characteristics of rockburst.Key factors for accurate prediction of rockburst intensity include uniaxial compressive strength,elastic energy index,the maximum principal stress,tangential stress,and their composite indicators.The accuracy of the proposed rockburst intensity level prediction expert system was verified using 20 engineering rockburst cases,with predictions aligning closely with the actual rockburst intensity levels.
文摘椎间盘由髓核、纤维环和软骨终板组成,对维持脊柱正常生理功能至关重要。椎间盘退变(intervertebral disc degeneration,IDD)是导致腰背痛等脊柱退行性疾病的主要病理基础,给人们的健康状况造成极大的困扰。然而目前对IDD的分子机制仍然缺乏清晰的了解,导致缺乏有效的靶向干预措施。RAS同源家族成员A(RAS homolog family member A,RhoA)/Rho相关蛋白激酶(Rho-associated protein kinase,ROCK)信号通路是调节细胞收缩、迁移和生长的经典通路。其被激活后可参与调控细胞骨架重塑、细胞外基质代谢、生物钟节律、细胞表型改变、细胞衰老及死亡等环节,进而影响IDD的病理进程。深入探究RhoA/ROCK信号通路在IDD中的作用,不仅能揭示疾病发生的分子生物学机制,也有望为研发靶向该通路的治疗策略提供理论依据。
基金Project(2022YFC2904103)supported by the National Key Research and Development Program of ChinaProjects(52374112,52274108)supported by the National Natural Science Foundation of China+1 种基金Projects(BX20220036,BX20230041)supported by the Postdoctoral Innovation Talents Support Program,ChinaProject(2232080)supported by the Beijing Natural Science Foundation,China。
文摘The development of metallic mineral resources generates a significant amount of solid waste,such as tailings and waste rock.Cemented tailings and waste-rock backfill(CTWB)is an effective method for managing and disposing of this mining waste.This study employs a macro-meso-micro testing method to investigate the effects of the waste rock grading index(WGI)and loading rate(LR)on the uniaxial compressive strength(UCS),pore structure,and micromorphology of CTWB materials.Pore structures were analyzed using scanning electron microscopy(SEM)and mercury intrusion porosimetry(MIP).The particles(pores)and cracks analysis system(PCAS)software was used to quantitatively characterize the multi-scale micropores in the SEM images.The key findings indicate that the macroscopic results(UCS)of CTWB materials correspond to the microscopic results(pore structure and micromorphology).Changes in porosity largely depend on the conditions of waste rock grading index and loading rate.The inclusion of waste rock initially increases and then decreases the UCS,while porosity first decreases and then increases,with a critical waste rock grading index of 0.6.As the loading rate increases,UCS initially rises and then falls,while porosity gradually increases.Based on MIP and SEM results,at waste rock grading index 0.6,the most probable pore diameters,total pore area(TPA),pore number(PN),maximum pore area(MPA),and area probability distribution index(APDI)are minimized,while average pore form factor(APF)and fractal dimension of pore porosity distribution(FDPD)are maximized,indicating the most compact pore structure.At a loading rate of 12.0 mm/min,the most probable pore diameters,TPA,PN,MPA,APF,and APDI reach their maximum values,while FDPD reaches its minimum value.Finally,the mechanism of CTWB materials during compression is analyzed,based on the quantitative results of UCS and porosity.The research findings play a crucial role in ensuring the successful application of CTWB materials in deep metal mines.
基金Projects(52578456,52208382)supported by the National Natural Science Foundation of ChinaProject(SKLGP2023K015)supported by the Opening Fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology),China。
文摘This study analyzed the interaction between sequentially installed combined support systems and the surrounding rock.Six distinct forms of elastic-brittle-plastic rock masses with reinforcement were analyzed,along with the critical displacements that governed their transition behaviors.Virtual support pressure was introduced to assess the spatial influence of the tunnel face.It was determined by integrating the longitudinal displacement profile with the proposed ground characteristic curve solutions under various ground conditions.Considering the timing of support installation,the support-rock interaction was divided into three phases.A method was presented to determine the evolution of this interaction based on critical displacements.An analytical approach was further proposed to describe the complete process of support system-rock interaction using displacement coordination.The analytical results are validated against numerical simulations and field measurements,and the method's advantages are demonstrated through comparisons with existing models and the convergence-confinement approach.Finally,the effects of surrounding rock and support parameters are examined.The results indicate that residual cohesion,the friction angle of reinforced ground,and reinforcement thickness strongly influence tunnel behavior.Additionally,increasing the stiffness or advancing the installation of secondary support substantially raises secondary support pressure.
基金Project(U22A20603)supported by the National Natural Science Foundation of ChinaProject(2023YFC3008300)supported by the National Key Research and Development Program of China。
文摘To investigate the long-term stability of soft-hard interbedded rock masses with initial damage induced by earthquakes and periodic drying and wetting,this study prepared samples with different initial damage through cyclic loading and unloading(CLU)experiments followed by cyclic drying and wetting(CDW)experiments,and finally conducted creep experiments.The study analyzed the effects of initial damage on creep mechanical behavior,crack evolution,and explored failure precursor information,revealing the damage failure mechanisms.The results show that the structural characteristics of the rock mass control its macroscopic failure mode.Initial damage promotes microcrack development,influences the fracture mode,and increases the proportion of high-frequency(200−280 kHz)acoustic emission events during creep.Meanwhile,initial damage exacerbates creep characteristics,increasing the creep rate,shortening total creep failure time,and reducing long-term strength.The damage failure is attributed to:the generation of internal cracks and pores in the rock caused by CLU;mineral hydrolysis and expansion-contraction due to CDW,resulting in weakened intergranular cementation;and full development of cracks and pores under creep stress.Additionally,the deformation difference coefficient and the coefficient of variation of RA/AF values can serve as precursor indicators for creep failure.
基金Project(2023AH051167)supported by the Natural Science Research Project of Anhui Educational Committee,ChinaProject(AHBP2024B-04)supported by the Foundation of Anhui Engineering Research Center of New Explosive Materials and Blasting Technology,China+1 种基金Project(GXZDSYS2023103)supported by the Open Fund for Anhui Key Laboratory of Mining Construction Engineering,ChinaProjects(52274071,52404155)supported by the National Natural Science Foundation of China。
文摘Aiming at the problem of dynamic instability of hard-brittle jointed rock surrounding in deep tunnel/roadway engineering,combining with the support concepts of"coupling rigidity with flexibility"and"overcoming rigidity by flexibility",the prevention and control method with"rigid-flexible coupling(R-F-C)"was put forward.Through numerical simulation calculation,the impact damage process,acoustic emission(AE)evolution characteristics,and element stress/displacement evolution characteristics of unsupported surrounding rock structure model,rigid supporting surrounding rock structure model,and"R-F-C"supporting surrounding rock structure model under horizontal bidirectional impact loading were compared and analyzed.Based on the theory of stress wave propagation,the dynamic instability catastrophe mechanism of three kinds of supporting structure models induced by horizontal bidirectional impact loading was revealed.Based on the Mohr-Coulomb strength theory,the stress discrimination methods of dynamic catastrophe of surrounding rock induced by horizontal bidirectional impact loading under three kinds of supporting structures were proposed.Combined with the above numerical simulation study,the explosion impact physical and mechanical test of"R-F-C"surrounding rock supporting plate structure was further designed and carried out.Finally,combined with the"conceptual model of ball-cliff potential energy instability",the energy driving theory and energy transformation mechanism of impact-induced rockburst under three kinds of supporting structures were discussed deeply.The research results provided a scientific basis for further promoting the effective application of"R-F-C"supporting structure in the prevention and control of dynamic instability of deep tunnel/roadway surrounding rock.
基金Project(TD20240003)supported by the Ordos Science&Technology Plan,ChinaProjects(52174096,52304110)supported by the National Natural Science Foundation of China。
文摘The stability of the roof in coal mining is crucial for ensuring safe extraction.Studying the mechanical behavior of rock beams under various conditions is essential for improving coal mining safety.However,research on the dynamic response of rock beams under sudden unloading remains limited.This study utilized a self-developed bidirectional loading and unilateral unloading test system to simulate how sudden lower strata subsidence induces the fracture of upper hard rock beams.Bottom unloading experiments were performed on rock beams with varying thicknesses and spans.The experiments recorded surface crack development and internal damage evolution using high speed photography and acoustic emission monitoring.The results show that rock beams experience multiple stress reductions after unloading,with the largest reduction occurring in the first stage.Flexural deformation was observed,becoming more pronounced as the thickness-span ratio decreased.Greater thickness increased shear cracks and crack expansion angles,while larger spans promoted tensile cracks,arched crack formation,and notable rock spalling.Acoustic emission analysis showed that signal count and energy increased with thickness and span.Finally,discrete element numerical simulations revealed the critical controlling role of harder rock strata in rock beam failure:when the harder strata are at the top,cracks are sharp,and shear failure is more likely;when they are at the bottom,the overall failure range expands,and cracks tend to form arches.These findings improve the understanding of dynamic rock beam fracture under sudden unloading and offer theoretical guidance for roof stability control in deep mining.
基金Project(41877272)supported by the National Natural Science Foundation of ChinaProject(2020zzts715)supported by the Fundamental Research Funds for the Central Universities of Central South University,ChinaProject(2242020R10023)supported by the Fundamental Research Funds for the Central Universities of Southeast University,China。
文摘To review the rockburst proneness(or tendency)criteria of rock materials and compare the judgment accuracy of them,twenty criteria were summarized,and their judgment accuracy was evaluated and compared based on the laboratory tests on fourteen types of rocks.This study begins firstly by introducing the twenty rockburst proneness criteria,and their origins,definitions,calculation methods and grading standards were summarized in detail.Subsequently,to evaluate and compare the judgment accuracy of the twenty criteria,a series of laboratory tests were carried out on fourteen types of rocks,and the rockburst proneness judgment results of the twenty criteria for the fourteen types of rocks were obtained accordingly.Moreover,to provide a unified basis for the judgment accuracy evaluation of above criteria,a classification standard(obtained according to the actual failure results and phenomena of rock specimen)of rockburst proneness in laboratory tests was introduced.The judgment results of the twenty criteria were compared with the judgment results of this classification standard.The results show that the judgment results of the criterion based on residual elastic energy(REE)index are completely consistent with the actual rockburst proneness,and the other criteria have some inconsistent situations more or less.Moreover,the REE index is based on the linear energy storage law and defined in form of a difference value and considered the whole failure process,and these superior characteristics ensure its accuracy.It is believed that the criterion based on REE index is comparatively more accurate and scientific than other criteria,and it can be recommended to be applied to judge the rockburst proneness of rock materials.
文摘目的探究毛兰素(Erianin)在特应性皮炎(atopic dermatitis,AD)中的作用及其在高迁移率族蛋白1(high mobility group box-1,HMGB1)/晚期糖基化终末产物受体(receptor for advanced glycation end products,RAGE)-Ras同源基因家族成员A(Ras homolog gene family member A,RhoA)/Rho关联含卷曲螺旋结合蛋白激酶1(recombinant Rho associated coiled coil containing protein kinase 1,ROCK1)信号通路中的调控机制。方法1-氯-2,4-二硝基苯(1-Chloro-2,4-dinitrobenzene,DNCB)诱导BALB/c小鼠作为AD的模型,测量小鼠的皮肤厚度、脾和淋巴结的重量。甲苯胺蓝和HE染色检测小鼠的背部皮肤和耳朵的病理改变;ELISA检测炎症因子水平;肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)刺激HaCaT细胞建立AD体外模型;采用流式细胞术检测细胞活性氧(reactive oxygen species,ROS);免疫荧光法检测线粒体活性氧(mitochondrion reactive oxygen species,mtROS);TUNEL检测细胞凋亡情况;免疫蛋白印迹法检测HMGB1、RAGE、RhoA、ROCK1蛋白表达情况。结果在体内实验中毛兰素抑制皮肤厚度的增加,减轻脾和淋巴结重量,改善炎症细胞的浸润和肥大细胞脱颗粒,降低炎症因子水平(P<0.05)。在体外实验中,毛兰素减少TNF-α诱导的HaCaT细胞ROS、mtROS的产生(P<0.01)。毛兰素治疗后HMGB1、RAGE、RhoA及ROCK1的蛋白表达量下降(P<0.01);使用RAGE特异性阻断剂(TFA)处理r-HMGB1刺激的HaCaT细胞后,HMGB1的表达没有发生变化,RAGE、RhoA及ROCK1表达减少(P<0.01);在Rho激酶抑制剂Y-27632+r-HMGB1组中,除RAGE的表达没有降低,其余结果与TFA+r-HMGB1组相近。结论毛兰素可能通过调节HMGB1/RAGE-RhoA/ROCK1信号通路缓解特应性皮炎。
基金Project(242102320036)supported by the Science and the Technology Development Plant of Henan Province,ChinaProject(52278367)supported by the National Natural Science Foundation of China。
文摘Composite rock layers are widely present in mining and tunnel construction projects,and are prone to dynamic tensile failure along bedding planes under dynamic disturbances.To ensure engineering safety,it is necessary to conduct research on the dynamic tensile characteristics under different working conditions.Considering the difficulty of on-site sampling,composite rock samples were prepared with cement mortar,and dynamic Brazilian splitting tests were carried out using split Hopkinson pressure bar(SHPB)equipment,a high-speed camera,and PFC^(2D)numerical software to explore their dynamic tensile properties under dynamic disturbance under different strength ratios and other factors.The results show that the dynamic tensile strength of samples exhibits a rising trend with the strength ratio and strain rate growth.As the incident angle increases from 0°to 90°,the stress contour deflects transform from center-splitting failure to tension-shear combined failure and back again.The influence of the incident order in different lithology rocks on the dynamic tensile strength of composite samples is controlled by strain rate,and when the strain rate increases to 400 s^(-1),the difference in strength due to the sequence of incident stress waves is within 5%.Based on PFC^(2D),the strength ratio of composite samples has a certain influence on the distribution of microfractures.With strength ratios equaling 1.5 or 2.0,the cracks are mainly concentrated on the softer material side,while a large number of cracks are distributed on both sides of the bedding plane with a strength ratio equal to 1.2.
基金Project(GZB202405561)supported by the Postdoctoral Fellowship Program of China Postdoctoral Science FoundationProject(42377154)supported by the National Natural Science Foundation of China。
文摘The shear performance of bolts plays a crucial role in controlling rock mass stability,and the roughness of the joint surface is one of the main factors affecting the mechanical properties of anchored joints.The 2nd generation of negative Poisson ratio(2G-NPR)bolt is a new independently developed material characterized by high strength and toughness.However,the influence of joint surface roughness on its anchorage shear performance remains unexplored.This study involves preparing regular saw-tooth jointed rock masses and conducting laboratory shear comparison tests on unbolted samples,2G-NPR bolts,and Q235 steel anchors.A three-dimensional finite element method,developed by the author,was employed for numerical simulations to analyze the influence of saw-tooth angles on the shear resistance of anchored bolts.The findings show that the anchorage of bolts enhances the shear strength and deformation of saw-tooth rock joints.The 2G-NPR bolts demonstrate superior performance in shear strength and deformation enhancement compared to Q235 steel anchors,including improved toughening and crack-arresting effects.Furthermore,the improvement of the shear strength and displacement of the bolt decreases with the increase of the joint saw-tooth angle.These findings provide a valuable test basis for the engineering application of 2G-NPR bolts in rock mass stabilization.
基金Projects(52208369,52309138,52108320)supported by the National Natural Science Foundation of ChinaProjects(2023NSFSC0284,2025ZNSFSC0409)supported by the Sichuan Science and Technology Program,ChinaProject(U22468214)supported by the Joint Fund Project for Railway Basic Research by the National Natural Science Foundation of China and China State Railway Group Co.,Ltd.
文摘In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefore,in this study,based on the stepped failure mode of bedding jointed rock slopes,considering the influence of the upper rock mass on the lower stepped sliding mass,the improved failure model for analyzing the interaction force(F_(AB))between two regions is constructed,and the safety factors(F_(S))of two regions and whole region are derived.In addition,this paper proposes a method to determine the existence of F_(AB) using their respective acceleration values(a_(A) and a_(B))when regions A and B are unstable.The influences of key parameters on two regions and the whole region are analyzed.The results show that the variation of the F_(AB) and F_(S) of two regions can be obtained accurately based on the improved failure model.The accuracy of the improved failure model is verified by comparative analysis.The research results can explain the interaction mechanism of two regions and the natural phenomenon of slope failure caused by the development of cracks.
