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
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
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
The spatial relationship between structural planes and principal stresses significantly affects the mechanical properties of deep hard rock.This paper examines the effect of the loading angle under true triaxial compr...The spatial relationship between structural planes and principal stresses significantly affects the mechanical properties of deep hard rock.This paper examines the effect of the loading angle under true triaxial compression.While previous studies focused on the angleβbetween the maximum principal stress and the structural plane,the role of angleω,between the intermediate principal stress and the structural plane,is often overlooked.Utilizing artificially prefabricated granite specimens with a single non-penetrating structural plane,we set the loading angleβto range from 0°to 90°across seven groups,and assignedωvalues of 0°and 90°in two separate groups.The results show that the peak strength is negatively correlated withβup to 45°,beyond which it tends to stabilize.The angleωexerts a strengthening effect on the peak strength.Deformation mainly occurs post-peak,with the strain values ε_(1) and ε_(3) reaching levels 2−3 times higher than those in intact rock.The structural plane significantly influences failure mode whenω=0°,while failure localizes near the σ_(3) surface of the specimens whenω=90°.The findings enhance data on structural plane rocks under triaxial compression and inform theoretical research,excavation,and support design of rock structures.展开更多
Gypsum rocks are highly susceptible to mechanical deterioration under the coupled effects of wet-dry(W-D)cycles and flow rates,which significantly influence the stability of underground excavations.Despite extensive r...Gypsum rocks are highly susceptible to mechanical deterioration under the coupled effects of wet-dry(W-D)cycles and flow rates,which significantly influence the stability of underground excavations.Despite extensive research on the effects of W-D cycles,the coupling influence of flow rates and W-D cycles on gypsum rocks remains poorly understood.This study investigates the mechanical behavior and deterioration mechanisms of gypsum rocks subjected to varying W-D cycles and flow rate conditions.Axial compression tests,along with nuclear magnetic resonance(NMR)techniques,were employed to analyze the stress-strain response and microstructural changes.Based on the disturbed state concept(DSC)theory,a W-D deterioration model and a DSC-based constitutive model were developed to describe the degradation trends and mechanical responses of gypsum rocks under different conditions.The results demonstrate that key mechanical indices,elastic modulus,cohesion,uniaxial compressive strength(UCS),and internal friction angle,exhibit logarithmic declines with increasing W-D cycles,with higher flow rates accelerating the deterioration process.The theoretical models accurately capture the nonlinear compaction behavior,peak stress,and post-peak response of gypsum specimens.This study provides valuable insights for predicting the mechanical behavior of gypsum rocks and improving the stability assessments of underground structures under complex environmental conditions.展开更多
Analyzing the fatigue damage characteristics of hot dry rock(HDR)affected by seawater thermal shock cycles is required for the efficient exploitation of HDR and the conservation of freshwater resources.Mechanical and ...Analyzing the fatigue damage characteristics of hot dry rock(HDR)affected by seawater thermal shock cycles is required for the efficient exploitation of HDR and the conservation of freshwater resources.Mechanical and acoustic emission(AE)monitoring tests were conducted during the triaxial compression of HDR at different confining pressures,temperatures,and numbers of seawater thermal shocks to investigate the seawater damage of HDR.The test results indicated an increase in the cumulative AE counts with increasing temperature and number of seawater thermal shocks,and a decrease in AE counts with increasing confining pressure.The effect of the number of seawater thermal shocks was significant.The AE counts were 276% higher at 15 than at 0 seawater thermal shocks.The b-value increased with the number of thermal shocks and stabilized after 5 shocks.Most of the damage was small fractures,which reduced the rock’s damage resistance.The AE time series under HDR triaxial compression exhibited multifractal features.High energy AE events dominated the damage mechanism of HDR,indicating shear damage to the HDR.Therefore,this study can provide a reference for seawater as a heat transfer fluid in the design of geothermal energy resource extraction.展开更多
This study proposed a new and more flexible S-shaped rock damage evolution model from a phenomenological perspective based on an improved Logistic function to describe the characteristics of the rock strain softening ...This study proposed a new and more flexible S-shaped rock damage evolution model from a phenomenological perspective based on an improved Logistic function to describe the characteristics of the rock strain softening and damage process.Simultaneously,it established a constitutive model capable of describing the entire process of rock pre-peak compaction and post-peak strain softening deformation,considering the nonlinear effects of the initial compaction stage of rocks,combined with damage mechanics theory and effective medium theory.In addition,this research verified the rationality of the constructed damage constitutive model using results from uniaxial and conventional triaxial compression tests on Miluo granite,yellow sandstone,mudstone,and glutenite.The results indicate that based on the improved Logistic function,the theoretical damage model accurately describes the entire evolution of damage characteristics during rock compression deformation,from maintenance through gradual onset,accelerated development to deceleration and termination,in a simple and unified expression.At the same time,the constructed constitutive model can accurately simulate the stress-strain process of different rock types under uniaxial and conventional triaxial compression,and the theoretical model curve closely aligns with experimental data.Compared to existing constitutive models,the proposed model has significant advantages.The damage model parameters a,r and β have clear physical meanings and interact competitively,where the three parameters collectively determine the shape of the theoretical stress−strain curve.展开更多
The stress gradient of surrounding rock and reasonable prestress of support are the keys to ensuring the stability of roadways.The elastic-plastic analytical solution for surrounding rock was derived based on unified ...The stress gradient of surrounding rock and reasonable prestress of support are the keys to ensuring the stability of roadways.The elastic-plastic analytical solution for surrounding rock was derived based on unified strength theory.A model for solving the stress gradient of the surrounding rock with the intermediate principal stress parameter b was established.The correctness and applicability of the solution for the stress gradient in the roadway surrounding rock was verified via multiple methods.Furthermore,the laws of stress,displacement,and the plastic zone of the surrounding rock with different b values and prestresses were revealed.As b increases,the stress gradient in the plastic zone increases,and the displacement and plastic zone radius decrease.As the prestress increases,the peak stress shifts toward the sidewalls,and the stress and stress gradient increments decrease.In addition,the displacement increment and plastic zone increment were proposed to characterize the support effect.The balance point of the plastic zone area appears before that of the displacement zone.The relationship between the stress gradient compensation coefficient and the prestress is obtained.This study provides a research method and idea for determining the reasonable prestress of support in roadways.展开更多
Aiming at the problem of deep surrounding rock instability induced by roadway excavation or mining disturbance,the true triaxial loading system was used to conduct graded cyclic maximum principal stress σ_(1) and int...Aiming at the problem of deep surrounding rock instability induced by roadway excavation or mining disturbance,the true triaxial loading system was used to conduct graded cyclic maximum principal stress σ_(1) and intermediate principal stress σ_(2) tests on sandstone to simulate the effect of mining stress in actual underground engineering.The influences of each principal stress cycle on the mechanical properties,acoustic emission(AE)characteristics,and fracture characteristics of sandstone were analyzed.The damage characteristics of sandstone under true triaxial cyclic loading were studied.Furthermore,the damage constitutive model of rock mass under true triaxial cyclic loading was established based on AE cumulative ringing count.The quantitative investigation was conducted on cumulative-damage changes in circulating sandstone,which elucidated the mechanism of damage deterioration in sandstone subjected to true triaxial cyclic loading.The results show that the influence of the graded cycleσ_(1) on limit maximum principal strain ɛ_(1max) and limit minimum principal strainɛ_(3max) was significantly greater than that of the limit intermediate principal strain ɛ_(2max).Graded cycleσ_(2) had a greater impact onɛ_(2max) and a smaller impact onɛ_(3max).The elasticity modulus of sandstone decreased exponentially with the increased cyclic load amplitude,while the Poisson ratio increased linearly.b of AE showed a trend of increasing,decreasing,slightly fluctuating,and finally decreasing during cyclingσ_(1).b showed a trend of slight fluctuation,large fluctuation,and finally increase during cyclingσ_(2).Sandstone specimens experienced mainly tensile failure,tensile-shear composite failure,and mainly shear failure with increased initialσ_(2) orσ_(3).This was determined by analyzing the rise angle-average frequency of the AE parameter,corresponding to the rock specimens from splitting failure to shear failure.Besides,the mechanical damage behavior of sandstone under true triaxial cyclic loading could be well described by the established constitutive model.At the same time,it was found that the sandstone damage variable decreased with increasedσ_(2) during cyclingσ_(1).The damage variable decreased first and then increased with increasedσ_(3) during cyclingσ_(2).展开更多
The special columnar jointed structure endows rocks with significant anisotropy,accurately grasping the strength and deformation properties of a columnar jointed rock mass(CJRM)under complex geological conditions is c...The special columnar jointed structure endows rocks with significant anisotropy,accurately grasping the strength and deformation properties of a columnar jointed rock mass(CJRM)under complex geological conditions is crucial for related engineering safety.Combined with the irregular jointed networks observed in the field,artificial irregular CJRM(ICJRM)samples with various inclination angles were prepared for triaxial tests.The results showed that the increase in confining pressure can enhance the ability of the ICJRM to resist deformation and failure,and reduce the deformation and strength anisotropic degrees.Considering the field stress situation,the engineering parts with an inclination angle of 30°−45°need to be taken seriously.Four typical failure modes were identified,and the sample with an inclination angle of 15°showed the same failure behavior as the field CJRM.Traditional and improved joint factor methods were used to establish empirical relationships for predicting the strength and deformation of CJRM under triaxial stress.Since the improved joint factor method can reflect the unique structure of CJRM,the predictive ability of the empirical relationship based on the improved method is better than that based on the traditional joint factor method.展开更多
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(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(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.
基金Projects(51979268,52279117,52309146)supported by the National Natural Science Foundation of ChinaProject(SKLGME-JBGS2401)supported by the Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,China。
文摘The spatial relationship between structural planes and principal stresses significantly affects the mechanical properties of deep hard rock.This paper examines the effect of the loading angle under true triaxial compression.While previous studies focused on the angleβbetween the maximum principal stress and the structural plane,the role of angleω,between the intermediate principal stress and the structural plane,is often overlooked.Utilizing artificially prefabricated granite specimens with a single non-penetrating structural plane,we set the loading angleβto range from 0°to 90°across seven groups,and assignedωvalues of 0°and 90°in two separate groups.The results show that the peak strength is negatively correlated withβup to 45°,beyond which it tends to stabilize.The angleωexerts a strengthening effect on the peak strength.Deformation mainly occurs post-peak,with the strain values ε_(1) and ε_(3) reaching levels 2−3 times higher than those in intact rock.The structural plane significantly influences failure mode whenω=0°,while failure localizes near the σ_(3) surface of the specimens whenω=90°.The findings enhance data on structural plane rocks under triaxial compression and inform theoretical research,excavation,and support design of rock structures.
基金Projects(52378392,52478390)supported by the National Natural Science Foundation of ChinaProject(2024J08213)supported by the Natural Science Foundation of Fujian Province,China+1 种基金Project(00387088)supported by the“Foal Eagle Program”Youth Top-notch Talent Project of Fujian Province,ChinaProject(GY-Z23072)supported by the Scientific Research Foundation of Fujian University of Technology,China。
文摘Gypsum rocks are highly susceptible to mechanical deterioration under the coupled effects of wet-dry(W-D)cycles and flow rates,which significantly influence the stability of underground excavations.Despite extensive research on the effects of W-D cycles,the coupling influence of flow rates and W-D cycles on gypsum rocks remains poorly understood.This study investigates the mechanical behavior and deterioration mechanisms of gypsum rocks subjected to varying W-D cycles and flow rate conditions.Axial compression tests,along with nuclear magnetic resonance(NMR)techniques,were employed to analyze the stress-strain response and microstructural changes.Based on the disturbed state concept(DSC)theory,a W-D deterioration model and a DSC-based constitutive model were developed to describe the degradation trends and mechanical responses of gypsum rocks under different conditions.The results demonstrate that key mechanical indices,elastic modulus,cohesion,uniaxial compressive strength(UCS),and internal friction angle,exhibit logarithmic declines with increasing W-D cycles,with higher flow rates accelerating the deterioration process.The theoretical models accurately capture the nonlinear compaction behavior,peak stress,and post-peak response of gypsum specimens.This study provides valuable insights for predicting the mechanical behavior of gypsum rocks and improving the stability assessments of underground structures under complex environmental conditions.
基金Projects(2024ZD1003903,2024ZD1003906)supported by the National Science and Technology Major ProjectProjects(U22A20166,52304097)supported by the National Natural Science Foundation of China+1 种基金Project(DUSE202301)supported by the Open Foundation of Key Laboratory of Deep Earth Science and Engineering(Sichuan University),Ministry of Education,ChinaProjects(2025A1515010049,2023A1515012654)supported by the Guangdong Basic and Applied Basic Research Foundation,China。
文摘Analyzing the fatigue damage characteristics of hot dry rock(HDR)affected by seawater thermal shock cycles is required for the efficient exploitation of HDR and the conservation of freshwater resources.Mechanical and acoustic emission(AE)monitoring tests were conducted during the triaxial compression of HDR at different confining pressures,temperatures,and numbers of seawater thermal shocks to investigate the seawater damage of HDR.The test results indicated an increase in the cumulative AE counts with increasing temperature and number of seawater thermal shocks,and a decrease in AE counts with increasing confining pressure.The effect of the number of seawater thermal shocks was significant.The AE counts were 276% higher at 15 than at 0 seawater thermal shocks.The b-value increased with the number of thermal shocks and stabilized after 5 shocks.Most of the damage was small fractures,which reduced the rock’s damage resistance.The AE time series under HDR triaxial compression exhibited multifractal features.High energy AE events dominated the damage mechanism of HDR,indicating shear damage to the HDR.Therefore,this study can provide a reference for seawater as a heat transfer fluid in the design of geothermal energy resource extraction.
基金Project(52074299)supported by the National Natural Science Foundation of ChinaProjects(2023JCCXSB02,BBJ2024083)supported by the Fundamental Research Funds for the Central Universities,China。
文摘This study proposed a new and more flexible S-shaped rock damage evolution model from a phenomenological perspective based on an improved Logistic function to describe the characteristics of the rock strain softening and damage process.Simultaneously,it established a constitutive model capable of describing the entire process of rock pre-peak compaction and post-peak strain softening deformation,considering the nonlinear effects of the initial compaction stage of rocks,combined with damage mechanics theory and effective medium theory.In addition,this research verified the rationality of the constructed damage constitutive model using results from uniaxial and conventional triaxial compression tests on Miluo granite,yellow sandstone,mudstone,and glutenite.The results indicate that based on the improved Logistic function,the theoretical damage model accurately describes the entire evolution of damage characteristics during rock compression deformation,from maintenance through gradual onset,accelerated development to deceleration and termination,in a simple and unified expression.At the same time,the constructed constitutive model can accurately simulate the stress-strain process of different rock types under uniaxial and conventional triaxial compression,and the theoretical model curve closely aligns with experimental data.Compared to existing constitutive models,the proposed model has significant advantages.The damage model parameters a,r and β have clear physical meanings and interact competitively,where the three parameters collectively determine the shape of the theoretical stress−strain curve.
基金Project(52274130)supported by the National Natural Science Foundation of ChinaProject(ZR2024ZD22)supported by the Major Basic Research Project of the Shandong Provincial Natural Science Foundation,China+2 种基金Project(2023375)supported by the Guizhou University Research and Innovation Team,ChinaProject(Leading Fund(2023)09)supported by the Natural Science Research Fund of Guizhou University,ChinaProject(JYBSYS2021101)supported by the Open Fund of Key Laboratory of Safe and Effective Coal Mining,Ministry of Education,China。
文摘The stress gradient of surrounding rock and reasonable prestress of support are the keys to ensuring the stability of roadways.The elastic-plastic analytical solution for surrounding rock was derived based on unified strength theory.A model for solving the stress gradient of the surrounding rock with the intermediate principal stress parameter b was established.The correctness and applicability of the solution for the stress gradient in the roadway surrounding rock was verified via multiple methods.Furthermore,the laws of stress,displacement,and the plastic zone of the surrounding rock with different b values and prestresses were revealed.As b increases,the stress gradient in the plastic zone increases,and the displacement and plastic zone radius decrease.As the prestress increases,the peak stress shifts toward the sidewalls,and the stress and stress gradient increments decrease.In addition,the displacement increment and plastic zone increment were proposed to characterize the support effect.The balance point of the plastic zone area appears before that of the displacement zone.The relationship between the stress gradient compensation coefficient and the prestress is obtained.This study provides a research method and idea for determining the reasonable prestress of support in roadways.
基金Project(2022m07020007)supported by the Key Research and Development Projects of Anhui Province,ChinaProjects(52174102,52074006,51404011,51874002,51974009)supported by the National Natural Science Foundation of China+1 种基金Project(2024cx1017)supported by the Graduate Innovation Fund of Anhui University of Science and Technology,ChinaProject(2024AH040067)supported by the Natural Science Research Project of Anhui Educational Committee,China。
文摘Aiming at the problem of deep surrounding rock instability induced by roadway excavation or mining disturbance,the true triaxial loading system was used to conduct graded cyclic maximum principal stress σ_(1) and intermediate principal stress σ_(2) tests on sandstone to simulate the effect of mining stress in actual underground engineering.The influences of each principal stress cycle on the mechanical properties,acoustic emission(AE)characteristics,and fracture characteristics of sandstone were analyzed.The damage characteristics of sandstone under true triaxial cyclic loading were studied.Furthermore,the damage constitutive model of rock mass under true triaxial cyclic loading was established based on AE cumulative ringing count.The quantitative investigation was conducted on cumulative-damage changes in circulating sandstone,which elucidated the mechanism of damage deterioration in sandstone subjected to true triaxial cyclic loading.The results show that the influence of the graded cycleσ_(1) on limit maximum principal strain ɛ_(1max) and limit minimum principal strainɛ_(3max) was significantly greater than that of the limit intermediate principal strain ɛ_(2max).Graded cycleσ_(2) had a greater impact onɛ_(2max) and a smaller impact onɛ_(3max).The elasticity modulus of sandstone decreased exponentially with the increased cyclic load amplitude,while the Poisson ratio increased linearly.b of AE showed a trend of increasing,decreasing,slightly fluctuating,and finally decreasing during cyclingσ_(1).b showed a trend of slight fluctuation,large fluctuation,and finally increase during cyclingσ_(2).Sandstone specimens experienced mainly tensile failure,tensile-shear composite failure,and mainly shear failure with increased initialσ_(2) orσ_(3).This was determined by analyzing the rise angle-average frequency of the AE parameter,corresponding to the rock specimens from splitting failure to shear failure.Besides,the mechanical damage behavior of sandstone under true triaxial cyclic loading could be well described by the established constitutive model.At the same time,it was found that the sandstone damage variable decreased with increasedσ_(2) during cyclingσ_(1).The damage variable decreased first and then increased with increasedσ_(3) during cyclingσ_(2).
基金Projects(42307192,41831278)supported by the National Natural Science Foundation of ChinaProject(CKWV20231175/KY)supported by the CRSRI Open Research Program,China。
文摘The special columnar jointed structure endows rocks with significant anisotropy,accurately grasping the strength and deformation properties of a columnar jointed rock mass(CJRM)under complex geological conditions is crucial for related engineering safety.Combined with the irregular jointed networks observed in the field,artificial irregular CJRM(ICJRM)samples with various inclination angles were prepared for triaxial tests.The results showed that the increase in confining pressure can enhance the ability of the ICJRM to resist deformation and failure,and reduce the deformation and strength anisotropic degrees.Considering the field stress situation,the engineering parts with an inclination angle of 30°−45°need to be taken seriously.Four typical failure modes were identified,and the sample with an inclination angle of 15°showed the same failure behavior as the field CJRM.Traditional and improved joint factor methods were used to establish empirical relationships for predicting the strength and deformation of CJRM under triaxial stress.Since the improved joint factor method can reflect the unique structure of CJRM,the predictive ability of the empirical relationship based on the improved method is better than that based on the traditional joint factor method.
