Negative Poisson ratio(NPR)steel is a new material with high strength and toughness.This study conducted tensile tests at elevated temperatures to investigate the mechanical properties of NPR steel at high temperature...Negative Poisson ratio(NPR)steel is a new material with high strength and toughness.This study conducted tensile tests at elevated temperatures to investigate the mechanical properties of NPR steel at high temperatures.The stress−strain curve,ultimate strength,yield strength,modulus of elasticity,elongation after fracture,and percentage reduction of area of NPR steel bars were measured at 9 different temperatures ranging from 20 to 800℃.The experimental results indicate that high-temperature environments significantly affect the mechanical properties of NPR steel.However,compared to other types of steel,NPR steel exhibits better resistance to deformation.When the test temperature is below 700℃,NPR steel exhibits a ductile fracture characteristic,while at 800℃,it exhibits a brittle fracture characteristic.Finally,based on the experimental findings,a constitutive model suitable for NPR steel at high temperatures is proposed.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
为进一步研究1 G NPR锚索加锚岩体的稳定性,以砂岩为研究对象,设计制作了试验1 G NPR锚索,分别对有侧限、无侧限约束条件下的无锚、普通锚索加锚、1 G NPR锚索加锚的岩石试件进行单轴试验及声发射试验研究。结果表明:在有侧限、无侧限2...为进一步研究1 G NPR锚索加锚岩体的稳定性,以砂岩为研究对象,设计制作了试验1 G NPR锚索,分别对有侧限、无侧限约束条件下的无锚、普通锚索加锚、1 G NPR锚索加锚的岩石试件进行单轴试验及声发射试验研究。结果表明:在有侧限、无侧限2种约束条件下,1 G NPR锚索加锚岩体单轴抗压强度相较于无锚提高至少20%、相较于普通锚索加锚提高9%以上;破坏特征方面,无锚试件是以张拉破坏为主的拉剪破坏且破坏后的碎散程度高。1 G NPR锚索加锚岩体主要以剪切破坏为主,1 G NPR锚索支护范围内的岩石形态较为完整,整体的碎散程度较低;从声发射角度来看,1 G NPR锚索的累积振铃计数仅为无锚的1/3。相较于无锚岩石试件的前期平缓增加,而在破坏瞬间产生大量的声发射振铃计数,1 G NPR锚索加锚岩石试件的前期呈现阶段增加趋势,在破坏瞬间声发射振铃计数并不会发生爆发式的突增现象。1 G NPR锚索提高了砂岩试件的峰值强度,同时,在峰后阶段,1 GNPR锚索通过多次结构滑移,释放了锚固岩体积累的能量,延缓了裂缝的开展与贯通,破坏后的试件碎散程度更低。展开更多
本研究旨在挖掘烟草抗南方根结线虫病程相关基因非表达子NPR1(non-expressor of PR genes)家族成员,并明确其功能。基于拟南芥AtNPR1家族成员蛋白序列,利用生物信息学方法鉴定分析烟草NtNPR1基因家族成员及其特征。通过qRT-PCR检测南方...本研究旨在挖掘烟草抗南方根结线虫病程相关基因非表达子NPR1(non-expressor of PR genes)家族成员,并明确其功能。基于拟南芥AtNPR1家族成员蛋白序列,利用生物信息学方法鉴定分析烟草NtNPR1基因家族成员及其特征。通过qRT-PCR检测南方根结线虫侵染后抗病(NC95)、感病(长脖黄)烟草品种Nt-NPR1家族重要候选抗性基因的相对表达量,采用LC-MS/MS方法对2个品种烟草根系内源水杨酸含量进行检测。结果表明,从普通烟草基因组中共鉴定到12个NtNPR1基因,这些基因被分为3个亚组,同一亚组中NtNPR1家族成员蛋白结构、保守基序的长度和位置都极为相似。编码氨基酸长度范围为462~588,均为亲水性蛋白,均位于细胞核。南方根结线虫侵染抗、感烟草品种后,根系中水杨酸含量、NtNPR1基因家族成员表达量在抗病品种中均升高,在感病品种中则降低,其中NtNPR6的变化最为明显。综上,NPR1基因与烟草南方根结线虫抗性密切相关,NtNPR6基因可作为烟草响应南方根结线虫胁迫的重要基因。展开更多
A study was conducted to analyze the deformation mechanism of strongly weathered quartz schist in the Daliangshan Tunnel,located in the western Transverse Mountain area.A large deformation problem was experienced duri...A study was conducted to analyze the deformation mechanism of strongly weathered quartz schist in the Daliangshan Tunnel,located in the western Transverse Mountain area.A large deformation problem was experienced during the tunnel construction.To mitigate this problem,a support system was designed incorporating negative Poisson ratio(NPR)anchor cables with negative Poisson ratio effect.Physical model experiments,field experiments,and numerical simulation experiments were conducted to investigate the compensation mechanical behavior of NPR anchor cables.The large deformations of soft rocks in the Daliangshan Tunnel are caused by a high ground stress,a high degree of joint fracture development,and a high degree of surrounding rock fragmentation.A compensation mechanics support system combining long and short NPR anchor cables was suggested to provide sufficient counter-support force(approximately 350 kN)for the surrounding rock inside the tunnel.Comparing the NPR anchor cable support system with the original support system used in the Daliangshan tunnel showed that an NPR anchor cable support system,combining cables of 6.3 m and 10.3 m in length,effectively prevented convergence of surrounding rock deformation,and the integrated settlement convergence value remained below 300 mm.This study provides an effective scientific basis for resolving large deformation problems in deeply buried soft rocks in western transverse mountain areas.展开更多
基金Projects(41702320,52104125)supported by the National Natural Science Foundation of ChinaProject(ZR2021MD005)+2 种基金supported by the Natural Science Foundation of Shandong Province,ChinaProject(TMduracon2022002)supported by the Engineering Research Center of Marine Environmental Concrete Technology,Ministry of Education,China。
文摘Negative Poisson ratio(NPR)steel is a new material with high strength and toughness.This study conducted tensile tests at elevated temperatures to investigate the mechanical properties of NPR steel at high temperatures.The stress−strain curve,ultimate strength,yield strength,modulus of elasticity,elongation after fracture,and percentage reduction of area of NPR steel bars were measured at 9 different temperatures ranging from 20 to 800℃.The experimental results indicate that high-temperature environments significantly affect the mechanical properties of NPR steel.However,compared to other types of steel,NPR steel exhibits better resistance to deformation.When the test temperature is below 700℃,NPR steel exhibits a ductile fracture characteristic,while at 800℃,it exhibits a brittle fracture characteristic.Finally,based on the experimental findings,a constitutive model suitable for NPR steel at high temperatures is proposed.
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.
文摘为进一步研究1 G NPR锚索加锚岩体的稳定性,以砂岩为研究对象,设计制作了试验1 G NPR锚索,分别对有侧限、无侧限约束条件下的无锚、普通锚索加锚、1 G NPR锚索加锚的岩石试件进行单轴试验及声发射试验研究。结果表明:在有侧限、无侧限2种约束条件下,1 G NPR锚索加锚岩体单轴抗压强度相较于无锚提高至少20%、相较于普通锚索加锚提高9%以上;破坏特征方面,无锚试件是以张拉破坏为主的拉剪破坏且破坏后的碎散程度高。1 G NPR锚索加锚岩体主要以剪切破坏为主,1 G NPR锚索支护范围内的岩石形态较为完整,整体的碎散程度较低;从声发射角度来看,1 G NPR锚索的累积振铃计数仅为无锚的1/3。相较于无锚岩石试件的前期平缓增加,而在破坏瞬间产生大量的声发射振铃计数,1 G NPR锚索加锚岩石试件的前期呈现阶段增加趋势,在破坏瞬间声发射振铃计数并不会发生爆发式的突增现象。1 G NPR锚索提高了砂岩试件的峰值强度,同时,在峰后阶段,1 GNPR锚索通过多次结构滑移,释放了锚固岩体积累的能量,延缓了裂缝的开展与贯通,破坏后的试件碎散程度更低。
文摘本研究旨在挖掘烟草抗南方根结线虫病程相关基因非表达子NPR1(non-expressor of PR genes)家族成员,并明确其功能。基于拟南芥AtNPR1家族成员蛋白序列,利用生物信息学方法鉴定分析烟草NtNPR1基因家族成员及其特征。通过qRT-PCR检测南方根结线虫侵染后抗病(NC95)、感病(长脖黄)烟草品种Nt-NPR1家族重要候选抗性基因的相对表达量,采用LC-MS/MS方法对2个品种烟草根系内源水杨酸含量进行检测。结果表明,从普通烟草基因组中共鉴定到12个NtNPR1基因,这些基因被分为3个亚组,同一亚组中NtNPR1家族成员蛋白结构、保守基序的长度和位置都极为相似。编码氨基酸长度范围为462~588,均为亲水性蛋白,均位于细胞核。南方根结线虫侵染抗、感烟草品种后,根系中水杨酸含量、NtNPR1基因家族成员表达量在抗病品种中均升高,在感病品种中则降低,其中NtNPR6的变化最为明显。综上,NPR1基因与烟草南方根结线虫抗性密切相关,NtNPR6基因可作为烟草响应南方根结线虫胁迫的重要基因。
基金Project(41941018)supported by the National Natural Science Foundation of China for the Special Project FundingProject(22-JKCF-08)supported by the Study on in-situ Stress Database and 3D in-situ Stress Inversion Technology of Highway Tunnel in Shanxi Province,China+1 种基金Project(2022-JKKJ-6)supported by the Study on Disaster Mechanism and NPR Anchor Cable Prevention and Control of Coal Mining Caving Subsidence in Operating Tunnel in Mountainous Area,ChinaProject(BBJ2024032)supported by the Fundamental Research Funds for the Central Universities(PhD Top Innovative Talents Fund of CUMTB),China。
文摘A study was conducted to analyze the deformation mechanism of strongly weathered quartz schist in the Daliangshan Tunnel,located in the western Transverse Mountain area.A large deformation problem was experienced during the tunnel construction.To mitigate this problem,a support system was designed incorporating negative Poisson ratio(NPR)anchor cables with negative Poisson ratio effect.Physical model experiments,field experiments,and numerical simulation experiments were conducted to investigate the compensation mechanical behavior of NPR anchor cables.The large deformations of soft rocks in the Daliangshan Tunnel are caused by a high ground stress,a high degree of joint fracture development,and a high degree of surrounding rock fragmentation.A compensation mechanics support system combining long and short NPR anchor cables was suggested to provide sufficient counter-support force(approximately 350 kN)for the surrounding rock inside the tunnel.Comparing the NPR anchor cable support system with the original support system used in the Daliangshan tunnel showed that an NPR anchor cable support system,combining cables of 6.3 m and 10.3 m in length,effectively prevented convergence of surrounding rock deformation,and the integrated settlement convergence value remained below 300 mm.This study provides an effective scientific basis for resolving large deformation problems in deeply buried soft rocks in western transverse mountain areas.
