The intersection is a widely used traffic line structure from the shallow tunnel to the deep roadway,and determining the subsidence hidden danger area of the roof is the key to its stability control.However,applying t...The intersection is a widely used traffic line structure from the shallow tunnel to the deep roadway,and determining the subsidence hidden danger area of the roof is the key to its stability control.However,applying traditional maximum equivalent span beam(MESB)theory to determine deformation range,peak point,and angle influence poses a challenge.Considering the overall structure of the intersection roof,the maximum equivalent triangular plate(METP)theory is proposed,and its geometric parameter calculation formula and deflection calculation formula are obtained.The application of the two theories in 18 models with different intersection angles,roadway types,and surrounding rock lithology is verified by numerical analysis.The results show that:1)The METP structure of the intersection roof established by the simulation results of each model successfully determined the location of the roof’s high displacement zone;2)The area comparison method of the METP theory can be reasonably explained:①The roof subsidence of the intersection decreases with the increase of the intersection angle;②The roof subsidence at the intersection of different roadway types has a rectangular type>arch type>circular type;③The roof subsidence of the intersection with weak surrounding rock is significantly larger than that of the intersection with hard surrounding rock.According to the application results of the two theories,the four advantages of the METP theory are compared and clarified in the basic assumptions,mechanical models,main viewpoints,and mechanism analysis.The large deformation inducement of the intersection roof is then explored.The J 2 peak area of the roof drives the large deformation of the area,the peak point of which is consistent with the center of gravity position of the METP.Furthermore,the change in the range of this peak is consistent with the change law of the METP’s area.Hence,this theory clarifies the large deformation area of the intersection roof,which provides a clear guiding basis for its initial support design,mid-term monitoring,and late local reinforcement.展开更多
To protect passengers, absorb enough kinetic energy and meet the special requirements for trains which are different from the other means of transportation, a method is presented to realize the plastic deformation thr...To protect passengers, absorb enough kinetic energy and meet the special requirements for trains which are different from the other means of transportation, a method is presented to realize the plastic deformation threshold based on three main aspects of train connection structure, crashworthy vehicle structure, energy-absorbing component. In practical engineering, trains need enough strength and stiffness to transfer longitudinal force under the normal operation condition, and have to produce controllable large plastic dcfbrmation to absorb energy shortly under the collision condition. To realize the structural damage threshold of connecting structure in terminal end, two control methods are also proposed which can be divided as the parametric method based on ＇extrusion＇ and ＇cutting＇ theories; the method which can cut the connecting components between coupler-buffer devices and train bodies and separate them away when the damage thresholds of coupler-buffer devices are more than the pre-supposed damage thresholds. The damage thresholds can be realized based on changing the parameters of the number of shearing bolts, material parameters, etc. To realize the collision threshold of energy-absorbing components of trains, a control method is presented based on the ways of setting plastic deformation induced structure, local hole and pre-deformation structure. To realize the threshold of the controllable plastic structure of energy-absorbing vehicles, a control method is proposed for the multi-level longitudinal stiffness of train terminal structures.展开更多
Being the core of the Songpan-Ganze block,Zoig(?) Basin is a favorable zone of oil and gas exploration. And it not only is the important deposition area of the northern Songpan-Garze in the Middle-Late Triassic, but a...Being the core of the Songpan-Ganze block,Zoig(?) Basin is a favorable zone of oil and gas exploration. And it not only is the important deposition area of the northern Songpan-Garze in the Middle-Late Triassic, but also impacts on the formation and evolution of the structural belt.To further understand the Zoig(?) Basin, we reprocessed the 0-20.0 s data of the Tangke-Hezuo deep seismic reflection profiles across the majority展开更多
Health state of shield tunnels is one of the most important parameters for structure maintenance.Usually,the shield tunnel is extremely long in longitude direction and composed by many segments.It is difficult to quan...Health state of shield tunnels is one of the most important parameters for structure maintenance.Usually,the shield tunnel is extremely long in longitude direction and composed by many segments.It is difficult to quantify the relationship between the structure damage state and shield tunnel structure deformation by the model test because of unpredictable effects of different scales between model test and prototype tunnel structure.Here,an in-situ monitoring project was conducted to study the excavation induced shield tunnel structure damage,which could be considered a prototype test on the tunnel deformation.The disaster performance of tunnel leakage,segment crack,segment dislocation and segment block drop-off during longitude deformation and cross-section ovality developments was analyzed.The results indicate that instead of the longitude deformation,the ovality value has the strongest correlation to the rest disease performance,which could be used as the assessment index of the tunnel health.For this tunnel,it is in health state when the ovality is less than 0.5%,and the serious damage could be found when the ovality value is higher than 0.77%.The research results provide valuable reference to shield tunnel health assessment and help complete the standard of shield tunnel construction.展开更多
In the present study,experimental and numerical investigations were carried out to examine the behavior of sandwich panels with honeycomb cores.The high velocity impact tests were carried out using a compressed air gu...In the present study,experimental and numerical investigations were carried out to examine the behavior of sandwich panels with honeycomb cores.The high velocity impact tests were carried out using a compressed air gun.A sharp conical nosed projectile was impacted normally and with some offset distance(20 mm and 40 mm).The deformation,failure mode and energy dissipation characteristics were obtained for both kinds of loading.Moreover,the explicit solver was run in Abaqus to create the finite element model.The numerically obtained test results were compared with the experimental to check the accuracy of the modelling.The numerical result was further employed to obtain strain energy dissipation in each element by externally running user-defined code in Abaqus.Furthermore,the influence of inscribe circle diameter and cell wall and face sheet thickness on the energy dissipation,deformation and failure mode was examined.The result found that ballistic resistance and deformation were higher against offset impact compared to the normal impact loading.Sandwich panel impacted at 40 mm offset distance required 3 m/s and 1.9 m/s more velocity than 0 and 20 mm offset distance.Also,increasing the face sheet and wall thickness had a positive impact on the ballistic resistance in terms of a higher ballistic limit and energy absorption.However,inscribe circle diameter had a negative influence on the ballistic resistance.Also,the geometrical parameters of the sandwich structure had a significant influence on the energy dissipation in the different deformation directions.The energy dissipation in plastic work was highest for circumferential direction,regardless of impact condition followed by tangential,radial and axial directions.展开更多
The Chamba\|Bharmaur syncline located in between Zanskar range in the north and Dhauladhar\|Pirpanjal range in the south , in the Chamba district of Western Himachal Pradesh. The rocks constituting Chamba\|Bharmaur sy...The Chamba\|Bharmaur syncline located in between Zanskar range in the north and Dhauladhar\|Pirpanjal range in the south , in the Chamba district of Western Himachal Pradesh. The rocks constituting Chamba\|Bharmaur syncline belong to Precambrian to Lr. Triassic (Rattan, 1973) and represent the southern extension of the Tethyan facies of the Zanskar Tethys Himalayan sequence (Thakur, 1998). The geological and structural mapping in the Chamba\|Bharmaur syncline reveal that the area comprises of various litho\|units which show imprint of various phases of deformation. Three main phases of deformation DF\-1, DF\-2 and DF\-3 have affected the rocks of the Chamba\|Bharmaur syncline. The earliest recognisable deformational structures of the area are tight isoclinal folds appressed with long drawn out limbs and thickened hinges have experienced buckle shortening of 80%. They have been rendered intrafolial folds in many places; only a few of them show disharmony. The folds initiated in the multilayered sequences are generally controlled in their distribution and wave\|length by more competent members of the sequence.展开更多
The Sangzhi-Shimen synclinorium, which is in the western margin region of the Hunan-Hubei Province and as the southeast part of the middle Yangtze platform, is a second-level tectonics unit in the south of this region...The Sangzhi-Shimen synclinorium, which is in the western margin region of the Hunan-Hubei Province and as the southeast part of the middle Yangtze platform, is a second-level tectonics unit in the south of this region. Along the profile, it can be divided into 5 third-level structure belts. By the comprehensive interpretation of seismic data and magnetotelluric (MT) sounding data, it is found that the surface structure is not in accordance with that of the underground, and this un-coordination can be conducted by many decollement surfaces between the layers. There are three periods of deformation in its geo-history in this region: before the early (Yanshan) stage, during the early Yanshan stage and after the early Yanshan stage, while the main deformation period is during the early (Yanshan) stage. And the mechanism of deformation is the thrust faults in basement, which are controlled by many decollements, in addition to the decollement of the cap-rock.展开更多
目的:回顾性分析脊柱胸椎前凸患者及正常人群术前影像学及超声心动图资料,探讨并分析胸椎前凸与患者心脏结构及功能的关系。方法:收集并分析2013年1月~2023年12月期间胸椎前凸患者和正常人群的影像学及超声心动图资料。根据胸椎角度将...目的:回顾性分析脊柱胸椎前凸患者及正常人群术前影像学及超声心动图资料,探讨并分析胸椎前凸与患者心脏结构及功能的关系。方法:收集并分析2013年1月~2023年12月期间胸椎前凸患者和正常人群的影像学及超声心动图资料。根据胸椎角度将纳入患者分为两组,A组为胸椎前凸(TL)组(T5-T12≤0°),27例;B组为胸椎后凸(TK)减小组(0°<T5-T12≤20°),29例;另设正常TK(20°<T5-T12≤40°)的C组为对照组,29例。收集三组人群术前临床、影像学及超声心动图资料,包括一般资料[性别、年龄、身高、体重、体重指数(BMI)、体表面积(BSA)],X线片影像学资料(胸椎冠、矢状面Cobb角),顶椎区CT影像学资料[脊柱穿透指数(spinal penetration index volume,SPIV)、顶椎区心脏容积比(cardiac volume ratio in apical vertebra region,CVRA)],超声心动图资料[左心室舒张末期内径(LVDd)、右心室舒张末期内径(RVDd)、左心房内径(LAD)、右心房内径(RAD)、右心室流出道(RVOT)、主动脉内径(AO)、升主动脉内径(AAO)、主肺动脉内径(MPA)、舒张末期室间隔厚度(IVST)、左心室后壁厚度(LVPWT)、射血分数(EF)、缩短分数(FS)、每搏输出量(SV)、心脏输出量(CO)、心脏指数(CI)、肺动脉收缩压(SPAP)]。采用SPSS 25.0统计分析软件对三组人群的上述资料进行统计、比较及相关性分析。结果:SPIV与矢状面Cobb角负相关,与冠状面Cobb角无相关性;SPIV与LVDd、RVDd、LAD、RAD、RVOT、AO、AAO、MPA、IVST、LVPWT呈负相关;SPIV与EF、FS、SV、CO、CI、SPAP无相关性;CVRA与矢状面Cobb角负相关,与冠状面Cobb角无相关性;CVRA与RVDd、IVST、LVPWT负相关;CVRA与LVDd、LAD、RAD、RVOT、AO、AAO、MPA之间无相关性;CVRA与EF、FS、SV、CO、CI、SPAP无相关性。结论:SPIV较CVRA更能反映胸椎前凸对心脏结构和功能的影响,胸椎后凸角度的减小可能加剧心脏血管负担。在胸椎前凸患者矫形手术过程中,由于全麻、俯卧位、胸骨及胸廓受压和肌松药物等因素,胸腔和心腔结构及功能参数可能发生显著变化,应特别关注气道阻塞和血流动力学不稳定的风险。展开更多
文章针对高超声速可变形减速器的飞行稳定性预测及回收着陆需求,研究表面结构变形对减速器气动特性的影响效应,重点分析了高度10~50 km、Ma=0.15~4.6关键速域内的静、动态气动特性变化。文章采用求解雷诺平均Navier-Stokes方程(Reynolds...文章针对高超声速可变形减速器的飞行稳定性预测及回收着陆需求,研究表面结构变形对减速器气动特性的影响效应,重点分析了高度10~50 km、Ma=0.15~4.6关键速域内的静、动态气动特性变化。文章采用求解雷诺平均Navier-Stokes方程(Reynolds average Navier-Stokes,RANS)的数值模拟方法,获得了有无表面结构变形减速器的流场和气动参数。定常计算结果表明:变形效应导致飞行器迎风面存在局部的小尺度流动分离,变形后外形的气动阻力增加。结合刚性动网格技术的俯仰强迫振动,计算结果表明:减速器的动态稳定性受到迎风面高压及背风面分离涡结构的共同作用,迎风面的高气动压力载荷占主导作用,使得减速器的动态稳定性增强;背风面的涡结构导致动态稳定性减弱;轴对称分布的表面结构变形整体上增强了减速器的动态稳定性。展开更多
基金Project(52204164)supported by the National Natural Science Foundation of ChinaProject(2021QNRC001)supported by the Young Elite Scientists Sponsorship Program by CAST,China。
文摘The intersection is a widely used traffic line structure from the shallow tunnel to the deep roadway,and determining the subsidence hidden danger area of the roof is the key to its stability control.However,applying traditional maximum equivalent span beam(MESB)theory to determine deformation range,peak point,and angle influence poses a challenge.Considering the overall structure of the intersection roof,the maximum equivalent triangular plate(METP)theory is proposed,and its geometric parameter calculation formula and deflection calculation formula are obtained.The application of the two theories in 18 models with different intersection angles,roadway types,and surrounding rock lithology is verified by numerical analysis.The results show that:1)The METP structure of the intersection roof established by the simulation results of each model successfully determined the location of the roof’s high displacement zone;2)The area comparison method of the METP theory can be reasonably explained:①The roof subsidence of the intersection decreases with the increase of the intersection angle;②The roof subsidence at the intersection of different roadway types has a rectangular type>arch type>circular type;③The roof subsidence of the intersection with weak surrounding rock is significantly larger than that of the intersection with hard surrounding rock.According to the application results of the two theories,the four advantages of the METP theory are compared and clarified in the basic assumptions,mechanical models,main viewpoints,and mechanism analysis.The large deformation inducement of the intersection roof is then explored.The J 2 peak area of the roof drives the large deformation of the area,the peak point of which is consistent with the center of gravity position of the METP.Furthermore,the change in the range of this peak is consistent with the change law of the METP’s area.Hence,this theory clarifies the large deformation area of the intersection roof,which provides a clear guiding basis for its initial support design,mid-term monitoring,and late local reinforcement.
基金Project(2005J002) supported by the Foundation of the Science and Technology Section of the Ministry of Railway of China
文摘To protect passengers, absorb enough kinetic energy and meet the special requirements for trains which are different from the other means of transportation, a method is presented to realize the plastic deformation threshold based on three main aspects of train connection structure, crashworthy vehicle structure, energy-absorbing component. In practical engineering, trains need enough strength and stiffness to transfer longitudinal force under the normal operation condition, and have to produce controllable large plastic dcfbrmation to absorb energy shortly under the collision condition. To realize the structural damage threshold of connecting structure in terminal end, two control methods are also proposed which can be divided as the parametric method based on ＇extrusion＇ and ＇cutting＇ theories; the method which can cut the connecting components between coupler-buffer devices and train bodies and separate them away when the damage thresholds of coupler-buffer devices are more than the pre-supposed damage thresholds. The damage thresholds can be realized based on changing the parameters of the number of shearing bolts, material parameters, etc. To realize the collision threshold of energy-absorbing components of trains, a control method is presented based on the ways of setting plastic deformation induced structure, local hole and pre-deformation structure. To realize the threshold of the controllable plastic structure of energy-absorbing vehicles, a control method is proposed for the multi-level longitudinal stiffness of train terminal structures.
文摘Being the core of the Songpan-Ganze block,Zoig(?) Basin is a favorable zone of oil and gas exploration. And it not only is the important deposition area of the northern Songpan-Garze in the Middle-Late Triassic, but also impacts on the formation and evolution of the structural belt.To further understand the Zoig(?) Basin, we reprocessed the 0-20.0 s data of the Tangke-Hezuo deep seismic reflection profiles across the majority
基金Projects(BK20150337,BK20140845,BK20140844)supported by the Natural Science Foundation of Jiangsu Province,ChinaProject(2015Y04)supported by the Transportation Science and Technology Project of Jiangsu Province,China+1 种基金Project(41504081)supported by the National Natural Science Foundation of ChinaProjects(2014M561567,2016T90416)supported by the China Postdoctoral Science Foundation
文摘Health state of shield tunnels is one of the most important parameters for structure maintenance.Usually,the shield tunnel is extremely long in longitude direction and composed by many segments.It is difficult to quantify the relationship between the structure damage state and shield tunnel structure deformation by the model test because of unpredictable effects of different scales between model test and prototype tunnel structure.Here,an in-situ monitoring project was conducted to study the excavation induced shield tunnel structure damage,which could be considered a prototype test on the tunnel deformation.The disaster performance of tunnel leakage,segment crack,segment dislocation and segment block drop-off during longitude deformation and cross-section ovality developments was analyzed.The results indicate that instead of the longitude deformation,the ovality value has the strongest correlation to the rest disease performance,which could be used as the assessment index of the tunnel health.For this tunnel,it is in health state when the ovality is less than 0.5%,and the serious damage could be found when the ovality value is higher than 0.77%.The research results provide valuable reference to shield tunnel health assessment and help complete the standard of shield tunnel construction.
文摘In the present study,experimental and numerical investigations were carried out to examine the behavior of sandwich panels with honeycomb cores.The high velocity impact tests were carried out using a compressed air gun.A sharp conical nosed projectile was impacted normally and with some offset distance(20 mm and 40 mm).The deformation,failure mode and energy dissipation characteristics were obtained for both kinds of loading.Moreover,the explicit solver was run in Abaqus to create the finite element model.The numerically obtained test results were compared with the experimental to check the accuracy of the modelling.The numerical result was further employed to obtain strain energy dissipation in each element by externally running user-defined code in Abaqus.Furthermore,the influence of inscribe circle diameter and cell wall and face sheet thickness on the energy dissipation,deformation and failure mode was examined.The result found that ballistic resistance and deformation were higher against offset impact compared to the normal impact loading.Sandwich panel impacted at 40 mm offset distance required 3 m/s and 1.9 m/s more velocity than 0 and 20 mm offset distance.Also,increasing the face sheet and wall thickness had a positive impact on the ballistic resistance in terms of a higher ballistic limit and energy absorption.However,inscribe circle diameter had a negative influence on the ballistic resistance.Also,the geometrical parameters of the sandwich structure had a significant influence on the energy dissipation in the different deformation directions.The energy dissipation in plastic work was highest for circumferential direction,regardless of impact condition followed by tangential,radial and axial directions.
文摘The Chamba\|Bharmaur syncline located in between Zanskar range in the north and Dhauladhar\|Pirpanjal range in the south , in the Chamba district of Western Himachal Pradesh. The rocks constituting Chamba\|Bharmaur syncline belong to Precambrian to Lr. Triassic (Rattan, 1973) and represent the southern extension of the Tethyan facies of the Zanskar Tethys Himalayan sequence (Thakur, 1998). The geological and structural mapping in the Chamba\|Bharmaur syncline reveal that the area comprises of various litho\|units which show imprint of various phases of deformation. Three main phases of deformation DF\-1, DF\-2 and DF\-3 have affected the rocks of the Chamba\|Bharmaur syncline. The earliest recognisable deformational structures of the area are tight isoclinal folds appressed with long drawn out limbs and thickened hinges have experienced buckle shortening of 80%. They have been rendered intrafolial folds in many places; only a few of them show disharmony. The folds initiated in the multilayered sequences are generally controlled in their distribution and wave\|length by more competent members of the sequence.
文摘The Sangzhi-Shimen synclinorium, which is in the western margin region of the Hunan-Hubei Province and as the southeast part of the middle Yangtze platform, is a second-level tectonics unit in the south of this region. Along the profile, it can be divided into 5 third-level structure belts. By the comprehensive interpretation of seismic data and magnetotelluric (MT) sounding data, it is found that the surface structure is not in accordance with that of the underground, and this un-coordination can be conducted by many decollement surfaces between the layers. There are three periods of deformation in its geo-history in this region: before the early (Yanshan) stage, during the early Yanshan stage and after the early Yanshan stage, while the main deformation period is during the early (Yanshan) stage. And the mechanism of deformation is the thrust faults in basement, which are controlled by many decollements, in addition to the decollement of the cap-rock.
文摘目的:回顾性分析脊柱胸椎前凸患者及正常人群术前影像学及超声心动图资料,探讨并分析胸椎前凸与患者心脏结构及功能的关系。方法:收集并分析2013年1月~2023年12月期间胸椎前凸患者和正常人群的影像学及超声心动图资料。根据胸椎角度将纳入患者分为两组,A组为胸椎前凸(TL)组(T5-T12≤0°),27例;B组为胸椎后凸(TK)减小组(0°<T5-T12≤20°),29例;另设正常TK(20°<T5-T12≤40°)的C组为对照组,29例。收集三组人群术前临床、影像学及超声心动图资料,包括一般资料[性别、年龄、身高、体重、体重指数(BMI)、体表面积(BSA)],X线片影像学资料(胸椎冠、矢状面Cobb角),顶椎区CT影像学资料[脊柱穿透指数(spinal penetration index volume,SPIV)、顶椎区心脏容积比(cardiac volume ratio in apical vertebra region,CVRA)],超声心动图资料[左心室舒张末期内径(LVDd)、右心室舒张末期内径(RVDd)、左心房内径(LAD)、右心房内径(RAD)、右心室流出道(RVOT)、主动脉内径(AO)、升主动脉内径(AAO)、主肺动脉内径(MPA)、舒张末期室间隔厚度(IVST)、左心室后壁厚度(LVPWT)、射血分数(EF)、缩短分数(FS)、每搏输出量(SV)、心脏输出量(CO)、心脏指数(CI)、肺动脉收缩压(SPAP)]。采用SPSS 25.0统计分析软件对三组人群的上述资料进行统计、比较及相关性分析。结果:SPIV与矢状面Cobb角负相关,与冠状面Cobb角无相关性;SPIV与LVDd、RVDd、LAD、RAD、RVOT、AO、AAO、MPA、IVST、LVPWT呈负相关;SPIV与EF、FS、SV、CO、CI、SPAP无相关性;CVRA与矢状面Cobb角负相关,与冠状面Cobb角无相关性;CVRA与RVDd、IVST、LVPWT负相关;CVRA与LVDd、LAD、RAD、RVOT、AO、AAO、MPA之间无相关性;CVRA与EF、FS、SV、CO、CI、SPAP无相关性。结论:SPIV较CVRA更能反映胸椎前凸对心脏结构和功能的影响,胸椎后凸角度的减小可能加剧心脏血管负担。在胸椎前凸患者矫形手术过程中,由于全麻、俯卧位、胸骨及胸廓受压和肌松药物等因素,胸腔和心腔结构及功能参数可能发生显著变化,应特别关注气道阻塞和血流动力学不稳定的风险。
文摘文章针对高超声速可变形减速器的飞行稳定性预测及回收着陆需求,研究表面结构变形对减速器气动特性的影响效应,重点分析了高度10~50 km、Ma=0.15~4.6关键速域内的静、动态气动特性变化。文章采用求解雷诺平均Navier-Stokes方程(Reynolds average Navier-Stokes,RANS)的数值模拟方法,获得了有无表面结构变形减速器的流场和气动参数。定常计算结果表明:变形效应导致飞行器迎风面存在局部的小尺度流动分离,变形后外形的气动阻力增加。结合刚性动网格技术的俯仰强迫振动,计算结果表明:减速器的动态稳定性受到迎风面高压及背风面分离涡结构的共同作用,迎风面的高气动压力载荷占主导作用,使得减速器的动态稳定性增强;背风面的涡结构导致动态稳定性减弱;轴对称分布的表面结构变形整体上增强了减速器的动态稳定性。
