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西南交通大学学报

西南交通大学学报

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Journal of Southwest Jiaotong University
本刊为全国核心期刊，并被《中国科学引文数据库》和《中国科技论文统计》收录为来源期刊。主要刊登理工类和经济管理等学科的基础理论研究、应用研究、实验研究、学术讨论等方面的学术论文以及科技信息报道。
  • 发文量：3580
  • 被引量：2245
  • H指数：3
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  • 维普期刊影响因子： 1.24
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  • 国内刊号/CN：51-1277/U
    国际刊号/ISSN：0258-2724
  • 发行周期：双月刊
    邮发代号：62-104
  • 主管单位：中华人民共和国教育部
    主办单位：西南交通大学
西南交通大学学报-联系信息
  • 主编：翟婉明
  • 电话：028-66367562 66366845
  • 邮箱：xbz@home.swjtu.edu.cn
  • 地址：四川省成都市高新区西部园区西南交通大学综合楼449,451室
  • 邮编：6111756
西南交通大学学报-获奖情况
  • • 中文版获2010年全国高校科技期刊精品奖
  • • 中文版获2010年四川省高校科技期刊精品奖
  • • 《西南交通大学学报》（中文版）荣获2009年全国高校科技期刊优秀编辑质量奖，学报编辑部有2人获优秀编辑工作者称号，两篇由编辑部老师发表的有关编辑学方面的论著分获优秀编辑学论著一、二等奖
  • • 获全国高校科技期刊优秀编辑出版质量奖
  • • 1999年获四川高校优秀学报、优秀期刊一等奖
  • • 1996年获铁路优秀科技期刊一等奖
  • • 1995年获全国高校学报一等奖，四川省“十佳期刊”
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西南交通大学学报 >2024年第5期
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  • 摘要：为研究盾构斜井管片衬砌与可压缩层联合支护体系中可压缩层参数对管片衬砌力学性能的影响,以神华新街台格庙矿区主斜井工程为依托,建立考虑管片衬砌与可压缩层之间接触效应和管片整环刚度折减效应的数值计算模型,分析有无可压缩层、不同可压缩层刚度及厚度等因素下管片衬砌内力和变形的分布规律和变化情况;采用相似模型试验对上述问题进行了进一步研究,并对有无可压缩层时管片的极限承载力和破坏形式进行了探讨.研究结果表明:可压缩层刚度越大,管片所受围岩压力越大且分布越不均匀,同时使得管片弯矩减小,轴力增大,当可压缩层模量与围岩模量之比在0. 1～0. 5之间变化时更为明显;随着可压缩层厚度的增大,管片所受围岩压力依次按不均匀、均匀、不均匀的趋势变化,当可压缩层厚度与管片厚度之比为1. 7时围岩压力最小,管片轴力则随可压缩层厚度的增大而减小;可压缩层存在与否对管片变形影响甚微,通过自身的挤密吸收围岩压力且促使应力重分布,从而减小并均匀化传递至管片上的荷载,使得管片内力随外荷载的增长更平缓,量值更小且分布更均匀,并使管片的极限承载力提高了40%;有无可压缩层时管片破坏均经历椭变、椭变加剧、裂缝出现和扩展、失稳破坏的过程,且有可压缩层时管片的破坏更严重.%In order to study the influence of the compressible layer parameters on the mechanical properties of the segmental lining in the combined support system of the inclined shaft constructed by shield,a numerical model considering the contact effect between the segmental lining and the compressible layer and the stiffness reduction of the segment ring was established based on the Main Inclined Shaft Project of Shenhua Xinjie Taigemiao Coal Mine Area,and the distribution characteristics and variation laws of the internal force and deformation of the segmental lining are analyzed under different factors such as the presence or absence,the stiffness and the thickness of compressible layer. Similar model tests were carried out to further investigate the above problems. The ultimate bearing capacity and the form of destruction are also discussed. The results show that the greater the compressible layer stiffness,the greater the and the more uneven distribution of the surrounding rock pressure on the segment,at the same time,the bending moment of the segment decreases and the axial force increases. It is more obvious when the ratio of compressible layer modulus to surrounding rock modulus varies from 0. 1 to 0. 5. With the increase of the compressible layer thickness,the surrounding rock pressure on the segment varies according to the trend of uneven to uniform and then again to uneven. When the ratio of the compressible layer thickness to the segment thickness is 1. 7,the pressure of the surrounding rock is the smallest. The axial force decreases with the increase of compressible layer thickness. The existence of compressible layer has little effect on the deformation of segmental lining. The model test results further show that the compressible layer can absorb the surrounding rock pressure and cause stress redistribution through its own compaction,so as to reduce and homogenize the load transferred to the segment,so that the internal force of the segment grows more smoothly with the external load smaller and more evenly distributed;and increased the ultimate bearing capacity of the segments by 40%. In the presence or absence of the compressible layer,the failure of the segment has experienced the processes of elliptic,elliptical exacerbation,the occurrence and expansion of the crack and instability. Moreover,the damage of the segment is more serious when the compressible layer is present. The research results of this paper can provide some reference for the design and construction of similar projects.
  • 摘要：Conventional locomotives and vehicles need to be transported to locomotive and vehicle manufacturing factories for large repair or overhaul from railway bureaus after they have attained a certain traveling mileage or run a certain number of years. Transporting locomotives and vehicles between railway bureaus and manufacturing factories for repair wastes the carrying capacity of railway lines,interferes with railway operation,and extends maintenance time. Besides,the maintenance time of EMUs needs to be minimised because of the high cost of EMUs. In summary,an EMU maintenance base (EMU depot)that combines overhaul and depot repair needs to be investigated. The process design of an EMU depot needs to be compatible with the maintenance of different types of EMUs,and the efficiency of the EMU depot needs to be improved. In order to solve the abovementioned problems, the general layout scheme and choice of land block of the EMU depot are studied. In addition,a scheme of underfloor vehicle-lifting machines for CRH2 and CRH3 EMU level 3 maintenance (depot repair)is studied. Finally,the efficient completion of a successive maintenance scheme for level 4 and 5 maintenance of a vehicle is presented. According to the design scheme presented herein,the combination of the overhaul and depot repair is first realised. In addition,the length of the vehicle- lifting elements of the machine can be adjusted within a range of 17. 375-17. 500 m,which achieves compatibility with the level 3 maintenance of CRH2 and CRH3 EMU. Further, the designed maintenance line is applicable to not only two eight-car EMUs but also a 16-car EMU. Moreover,level 4 and 5 maintenance of a vehicle can be completed within 80 min. With the proposed scheme,the specialisation of every maintenance station and process can be realised. The cross operation among different maintenance groups is avoided. A clean assembly station of car body parts is guaranteed,and maintenance efficiency and quality are improved.%传统列车运行达到一定的走行公里或年限后,机车和车辆需从各铁路局分别送到机车、车辆制造工厂迸行(大)厂修,待修机车车辆在铁路局与机车车辆制造工厂之间往返过程中有占用铁路通过能力、干扰正线运营、检修周期长的弊病,动车组价格昂贵要求停修时间尽量缩短,因此需要研究设计厂修、段修合一的动车组检修基地即动车段.动车段的工艺设计要求兼容不同类型动车组检修,且动车段检修效率要高.为了解决上述问题,研究了厂修、段修合一的动车段总平面布局方案和段址方案,以及CRH2型、CRH3型动车组三级修(段修)的地坑式架车机方案,并研究了四、五级修快速完成1节车检修的流水检修方案.根据研究设计的方案,实现了厂修、段修房屋组合;使CRH2型、CRH3型动车组三级修(段修)地坑式架车机的架车单元在17. 375～17. 500 m范围连续可调,实现了CRH2型、CRH3型三级修兼容,一条检修线检修两组8辆编组的动车组,又能检修16辆固定编组动车组;并实现了四、五级修每80 min完成1节车检修,各检修工位工序专业化检修,避免了各检修专业组间交叉作业,保证车体部件组装工位环境清洁,提高了检修效率和质量.
  • 摘要：为探讨乘客身材特征对地铁客室中乘坐设备功能尺寸设计的影响,运用人机工程学以人为中心的实验和相关分析法展开研究.围绕人的生理结构、心理尺度和乘坐设备的功能属性等因素,结合压力分布实验、虚拟仿真技术和主观评价分析,对人与地铁座椅和扶手之间的功能尺寸配置关系进行了测试与分析.研究结果表明:座椅腰靠纵向外凸圆弧的曲率半径为186 mm、座垫横向内凹圆弧的曲率半径为785 mm时更贴近人体坐姿的生理曲度和满足乘坐的舒适性要求;扶手的吊环高度设置在1 710 mm、横杆高度设置在1 860 mm时能够分别保障不同身材的乘客的使用需求,并能满足适用性、安全性和通行性之间的平衡.%A human-centred experiment and ergonomic correlation-analysis approach was adopted to investigate the impact of passenger body size on the functional dimension design of riding equipment in subway passenger compartments. Subsequently,the relationship between the functional dimension configuration among passengers,subway seats,and handrails was tested and analysed based on human physiological structure,psychological endurance,and functional properties of riding equipment. This was achieved by combining a pressure distribution experiment with virtual simulation technology and subsequent subjective evaluation and analysis. Results demonstrate that when the curvature radius of the backrest outer convex arc measures 186 mm while that of the cushion inner concave arc measures 785 mm,seat surface closely matches the physiological curvature of the body-sitting posture,thereby meeting the requirements of riding comfort. Also,when the height of handrail rings and that of cross rods are set as 1 710 mm and 1 860 mm,respectively,handrail height meets usage requirements of passengers having different bodies sizes as well as that of balance between applicability,safety,and accessibility.
  • 摘要：Semi-closed sound barriers are increasingly used in high-speed railway engineering, however,research on its noise reduction effect in operation is extremely limited. Based on the Shanghai to Kunming passenger line,noise measurement points were respectively arranged on the inner and outer surface of the semi-closed sound barrier,and the opened and closed sides,at different distances. Noise signals during high-speed train passing-by were monitored. Acoustic characteristics in terms of sound pressure level spectrum,sound field distribution,attenuation law,sound insulation and insertion loss were discussed. Results indicate that the reverberation effect caused by multiple reflections increases the noise on the inner surface of the semi-closed sound barrier;at a distance of 7. 5 m from the track centerline ,the sound pressure level of the higher measuring point is larger than that of the lower measuring point ,and the directivity of the noise distribution is not evident for other measuring points at different heights. The sound insulation of the semi-closed sound barrier increases with the increase in frequency and reaches a peak of 26 dB at 1000 Hz;the insertion loss at a distance of 7. 5 m and 25 m from the track centerline is 16. 5 dB(A)and 15. 5 dB(A),respectively.%当前半封闭式声屏障逐渐在高速铁路工程中得到了应用,但其在运营状态下的实际降噪效果研究还极其有限.为此,以沪昆客专杭长段半封闭式声屏障为工程背景,分别在声屏障内、外表面,以及封闭侧和敞开侧不同距离处布置测点,监测高速列车通过时的噪声,并对场点的声压级频谱、声场分布、衰减规律、隔声量和插入损失等声学特性进行讨论.结果表明:多重反射造成的混响效应使得半封闭式声屏障内表面的噪声有所增大;距封闭侧线路中心7. 5 m处,高位测点比低位测点声压级大,而其他位置不同高度测点在垂向的指向性不明显.半封闭式声屏障的隔声量随频率增加而增大,在1 000 Hz处最大约26 dB;距轨道中心线7. 5 m和25 m处的插入损失均值为16. 5 dB(A)和15. 5 dB(A).
  • 摘要：静风效应产生的附加风攻角对大跨度桥梁的颤振性能有着重要的影响,因此研究不同风攻角下主梁的颤振机理有重要意义.以扁平箱梁为研究对象,基于不同攻角下的颤振导数,采用双模态耦合解法掌握了颤振性能,继而通过分析气动阻尼、相位差和气动力幅值的变化研究了颤振机理.研究结果表明:在0°和3°攻角下,非耦合气动力为扁平箱梁断面提供了较大的正阻尼,颤振临界风速较高;在5°攻角下,非耦合气动力产生的正阻尼显著减小,使得耦合气动力产生的负阻尼迅速增加,导致颤振临界风速显著降低;耦合运动相位角增大是大攻角下气动负阻尼增加的主要原因,耦合气动力振幅则对颤振风速没有影响;此颤振机理表明大攻角下扁平箱梁颤振性能的弱化是由耦合效应增大引起,而非扭转运动产生的气动负阻尼引起.%The effect of an additional attack angle induced by aerostatic force on flutter instability of long span bridges is significant,thus the study regarding the flutter mechanisms of a flat box girder under different attack angles is important and necessary. Flutter derivatives have been identified using forced vibration devices and the critical velocities have been calculated based on the bimodal coupled flutter analysis method. Based on this analysis scheme,the roles of aerodynamic damping,phase lag, and modal frequency,which aid to better understand the flutter mechanism of the girder under different attack angles,are intensively analysed. The study results indicate that uncoupled aerodynamic forces provide energy to enhance the stability of the systems that result in a higher critical flutter speed at 0° and 3° compared with the speed at 5° The negative aerodynamic damping induced by the coupled force increases rapidly while the positive damping provided by the non-coupled force decreases significantly at 5° attack angle,which results in the weakened flutter performance. The phase lag of coupled flutter is the primary parameter for increasing the negative damping,and the effect of aerodynamic amplitude is negligible. The mechanism indicates that the weakening flutter performance of a flat box girder at large attack angle is increased primarily owing to coupled motion,not induced by negative damping generated in the torsional flutter.
  • 摘要：为对标准Ⅲc型轨枕进行外形优化及揭示轨枕优化前后道床横向阻力特性,针对Ⅲc型轨枕特定部位增设混凝土加宽(加厚)块,形成3种框架式轨枕,结合道床横向阻力测试实验,分析对比不同道床断面形式下(砟肩宽度300 mm堆高0 m;砟肩宽度500 mm堆高0 m;砟肩宽度500 mm堆高150 m)各框架轨枕与标准Ⅲc型轨枕道床横向阻力数值.研究结果表明:在不同道床断面型式下,各型框架轨枕均能有效增大道床横向阻力,相较于标准Ⅲc型轨枕,A型框架轨枕(轨枕承轨台双翼缘型)可提升道床横向阻力37. 8% ～50. 8%,B型框架轨枕(枕中截面十字型)可提升道床横向阻力25. 5% ～41. 0%,C型框架轨枕(轨枕承轨台下底部加厚型)可提升道床横向阻力13. 3% ～23. 0%.%To optimize the geometry of the Ⅲc mono-block sleeper and reveal the variation characteristics of the ballast bed lateral resistance before and after optimization,three different frame sleepers were designed and fabricated by adding concrete blocks to specific parts of theⅢc mono-block sleeper. Based on the ballast bed lateral resistance test,The frame sleepers and Ⅲc mono-block sleeper were compared for different ballast bed cross-sections (shoulder width 300 mm,shoulder height 0 mm;shoulder width 500 mm,shoulder height 0 mm;shoulder width 500 mm,and shoulder height 150 mm). The study shows that each frame sleeper can effectively increase lateral resistance with different ballast bed cross-sections. Furthermore,compared with the Ⅲc mono-block sleeper,there is 37. 8% - 50. 0% increase in lateral resistance for frame sleeper type A (end-winged sleeper ), 25. 5% -41. 0% increase for frame sleeper type B(middle-winged sleeper),and 13. 3% -23. 0%increase for frame sleeper type C(bumped sleeper ).
  • 摘要：为实现以剪切为主的(剪跨比不大于2. 0)钢筋混凝土剪力墙力-位移全过程计算,在拉压杆模型基础上通过合理化假定提出了考虑变形协调的改进拉压杆模型.模型由对角斜向混凝土压杆、混凝土次斜压杆、混凝土次生斜压杆、水平拉杆、竖向拉杆及墙肢分布筋拉杆等组成,定量确定了模型中对角斜压杆及次斜压杆变形与墙端位移间的关系,建立了各杆件之间的变形协调条件、物理方程和平衡方程等计算式.此外应用该模型分析了轴压比,剪跨比及墙肢分布配筋率三种参数对剪力墙力-位移骨架曲线的影响.研究结果表明:与6片剪力墙试验结果对比,该模型能够较好地模拟剪跨比不大于2. 0、以剪切受力特征为主的钢筋混凝土剪力墙力-位移骨架曲线;当轴压比由0. 1依次增至0. 5时,峰值承载力最大增量为27%;剪跨比由1. 0依次增至2. 0时,峰值承载力最大减少30%;分布配筋率由0. 25%依次增至0. 55%时,峰值承载力最大增量为6%;相比于其余两个参数,配筋率对墙肢承载能力的影响最小.%An improved strut-and-tie model that considers the deformation compatibility for determining the load-deformation relationship for squat walls (shear span ratio smaller than 2. 0 )is proposed. The model originates from the strut-and-tie model,and it includes a diagonal concrete strut, secondary concrete struts, subsidiary concrete struts, horizontal tie, vertical tie, and shear reinforcement ties. A definite equation between the deformation of two types of concrete struts (a diagonal concrete strut and four secondary concrete struts)and the displacement of the squat walls is given. The relationship among compatibility,equilibrium,and constitutive laws in each of the strut and ties was established. In addition,parameter analyses were conducted using the improved strut-and-tie model to study the effect of axial load,aspect ratio,and distribution reinforcement ratio on the skeleton curves of shear walls. The results show that,compared with the test results for six shear walls,the forces and deformations of the predicted members' are in reasonable agreement with test results. During parameter analysis,when the axial load ratio increases from 0. 1 to 0. 5,the maximum growth of load-carrying capacity is 27%. As the aspect ratio of shear walls increases from 1. 0 to 2. 0, the load-carrying capacity decreases 30%. As the distribution reinforcement ratio increases from 0. 25% to 0. 55%,the load-carrying capacity increases only 6%. The effect of the distribution reinforcement ratio on load-carrying capacity is not significant compared with the other two parameters.
  • 摘要：To analyse the effect of impulsive disturbances on neural networks, the dynamical behaviour of these disturbances was examined at the module of the equilibrium point of a class of complex-valued Cohen-Grossberg neural networks with time-varying delays. It was assumed that amplification,self-feedback,and activation functions were defined in a complex number domain. First,the existence and uniqueness of the equilibrium point of the system were analysed by utilising the corresponding property of the M matrix and the theorem of homeomorphism mapping. Second,the globally exponential stability of the module of the equilibrium point of the system was studied by applying the vector Lyapunov function and mathematical induction methods. The corresponding stability criteria were then established. Finally,two numerical examples from simulations were given to illustrate the practicability and correctness of the obtained results. The simulation results revealed that the states of the addressed system can reach equilibrium within 0. 5 s. Other results showed that the greater the delay and impulsive strength and the smaller the amplification,the slower was the state convergence rate.%为了分析脉冲干扰因素对复数域神经网络的影响,研究了一类具有脉冲干扰的变时滞复数域Cohen-Grossberg神经网络的平衡点的动态行为. 在假定放大函数、自反馈函数以及激活函数定义在复数域的情况下,首先,利用M矩阵和同胚映射的相关原理,分析了该系统平衡点的存在性和唯一性;其次,利用向量Lyapunov函数法以及数学归纳法,研究了该系统平衡点的全局模指数稳定性,并建立的稳定性判据;最后,通过两个数值仿真算例验证了所得结论的实用性和正确性. 仿真结果显示系统状态在0. 5 s便可收敛到平衡状态. 研究结果表明:时滞和脉冲干扰强度越大、放大函数越小,则神经元状态的指数收敛速度越慢.
  • 摘要：针对燃气轮机使用过程中由于工作状态突变导致轮机性能估计困难的问题,提出基于残差相似性的渐消无迹卡尔曼滤波(fading unscented Kalman filter with residual similarity,FUKF-RS)算法,实现燃气轮机健康参数的估计.首先,在普通渐消无迹卡尔曼滤波(fading unscented Kalman filter,FUKF)框架下,构造燃气轮机健康参数估值算法,在测量值估计更新过程中,乘以渐消因子来调节前后时刻的权重,通过强制残差正交来估计渐消因子;然后,利用前后估值时刻残差向量的余弦值表征残差阵的相似度,根据其相似度的大小关系确定残差阵的比例;最后,用该比例值代替算法中的遗忘因子,计算残差阵,实现求解的量化取值.研究结果表明:在燃气轮机状态突变条件下,FUKF-RS算法具有突变状态跟踪能力,参数估值精度比FUKF算法提高了3%左右,普通UKF (unscented Kalman filter,UKF)则不具突变状态跟踪能力;在部件性能缓慢变化时,参数的估计曲线比普通FUKF更平滑,估计精度提高了2%左右.%Owing to the difficulty in assessing the performance of a gas turbine during usage,because of sudden changes in its operation state,the use of an fading unscented Kalman filter with residual similarity (FUKF-RS)algorithm for the health parameter estimation of a gas turbine is proposed in this study. At first,under the common fading unscented Kalman filter (FUKF)framework,the health parameter estimation algorithm of the gas turbine was built. The weights before and after estimation were adjusted by multiplying the fading factor with the variance of measured value during the updating process of estimation;the fading factor was estimated by keeping the residual vectors to be orthogonal. Then,the similarity of the residual matrix was represented by the cosine value of the residual vector before and after the estimation,and the proportion of residual matrixes was determined according to the magnitude of the similarity. Finally,the fading factor of the algorithm was substituted by such proportion to calculate the residual matrix and obtain the quantitative parameter required for the calculation. The results show that the FUKF-RS algorithm can trace the sudden change of state of the gas turbine,and its accuracy in parameter estimation is higher by approximately 3% as compared to that of the FUKF algorithm. Additionally, as the component performance changes slowly, the parameter estimation curve will be smoother than that of the common FUKF,and the estimation accuracy will be increased by approximately 2%.
  • 摘要：In order to solve the fatigue problem of orthotropic steel bridge decks,an innovative corrugated steel plate-UHPC (ultra-high performance concrete ) layer composite deck structure is proposed based on the cause of the fatigue problems and the basic approaches used to improve the anti-fatigue performance. First,the major design parameters that significantly impact mechanical properties and the corresponding ranges of the parameter values were determined using parametric analysis. A model based on the BP artificial neural network was developed to determine the optimal design of the innovative structure system. Finally,the fatigue performance of the optimal structure was studied. The results show that the number of geometric discontinuity locations and weld joints are decreased,while the local stiffness of the deck plate is increased. According to the results of the parametric analysis, the height of the corrugated steel plate and the width of the top and bottom horizontal parts of the plate play important roles in structure mechanical characteristics. The proposed optimal design model based on the BP(back propagation)artificial neural network is suitable for the optimal design of innovative structure systems,and the maximum error is 4. 4%. The innovative bridge deck has good fatigue performance,and its fatigue life is over 200 years,which provides a comprehensive solution to the fatigue problem and has good potential for further development and application.%为解决正交异性钢桥面板的疲劳问题,从其根本原因和提高其抗疲劳性能的基本途径出发,提出一种新型波形顶板-UHPC(超高性能混凝土)组合桥面板结构体系.确定影响新型桥面板受力特性的主要参数及其合理取值范围,使用基于BP(back propagation)神经网络的优化设计模型对结构进行优化设计,就所优化的结构尺寸进行疲劳性能测试.研究结果表明:该结构能大幅减少桥面板结构中的几何构型不连续部位数量和焊缝数量,显著提高顶板局部刚度;波形钢板高度、顶部和底部水平段宽度是结构受力性能的重要影响参数;基于BP神经网络的优化设计模型适用于该类桥面板结构的优化设计,最大误差为4. 4%;新的结构体系具有良好的疲劳性能,疲劳寿命超过200 a,为正交异性钢桥面板的疲劳问题提供了较好的综合解决方案.
  • 摘要：为了研究地震破坏下高速铁路连续梁桥发生破坏的可能性,根据地震风险性(risk)为地震危险性(hazard)与易损性(fragility)乘积的定义,基于失效概率法,对高速铁路连续梁桥地震风险评估方法进行了分析.通过条带法建立桥梁地震需求模型,基于可靠度函数获得桥梁地震易损性曲线,拟合得到桥梁易损性概率密度函数;根据桥址处地震危险性资料,推导桥址处地震加速度概率密度函数;通过地震加速度概率密度函数与桥梁结构易损性概率密度函数的数值积分,实现桥梁地震风险概率评估.以一座(32+48+32)m高速铁路连续梁桥为例系统演绎了失效概率法桥梁风险评估的实现过程.研究结果表明:当地震危险性资料缺乏或不足时可以通过地震烈度分布函数及其与地震峰值加速度之间的换算关系,推导和完善地震危险性分析资料;对于高速铁路(32+48+32)m连续梁桥100年设计期间内发生轻微损伤的概率为5. 16%,发生中等损伤的概率为4. 46%,桥梁受到轻微损伤和中等损伤风险概率接近,几乎不可能发生严重损伤和完全破坏.%To study the possibility of destruction of a high-speed railway continuous girder bridge under the influence of seismic damage,a seismic risk assessment of the bridge was conducted. The failure probability method was used,in which seismic risk is defined as the product of seismic hazard and fragility (i. e. ,seismic risk＝seismic hazard×fragility). The bridge seismic demand model was established using the strip coating method. The bridge seismic fragility curve was obtained based on the reliability function,and the probability density function of the bridge fragility was fitted. According to seismic risk data of the bridge site,the probability density function of seismic acceleration of the bridge site was derived. The probability density function of seismic acceleration was numerically integrated with that of the bridge structural vulnerability to accomplish the probability evaluation of the bridge earthquake risk. Taking a (32 +48 +32 ) m high-speed railway continuous girder bridge as an example,the system conducted the bridge risk assessment using the failure probability method. The results show that when earthquake risk data are lacking or insufficient,it is possible to deduce and improve seismic risk analysis data using the conversion relation between the earthquake intensity distribution function and the seismic peak acceleration. For the high-speed railway (32+48+32)m continuous girder bridge,within 100 years of use,the occurrence probability of slight damage is 5. 16% and that of secondary damage is 4. 46%. The probabilities of slight damage and secondary damage risk of the bridge are similar,whereas the probabilities of serious damage and complete destruction are very small,indicating that serious damage and complete destruction are almost impossible.
  • 摘要：The measurement of high-speed railway track irregularities is a complex stochastic process, in which many single-component signals of different frequencies and amplitudes are present. In order to analyse the distribution characteristics of track irregularities in the spatial and frequency domains,the Hilbert-Huang transform was used to extract the energy distribution of track irregularity in the time-frequency domain. Track irregularity data was first decomposed into amplitude-frequency modulated multivariate intrinsic mode functions (IMF)at different scales,based on the data-driven filtering characteristics of multivariate empirical mode decomposition (MEMD). The instantaneous frequency of multivariate IMFs at each scale was then calculated by means of a Hilbert transform,from which the frequency and energy distribution characteristics were analysed. The analysis of the track inspection car indicates that the frequency distribution of track irregularities exhibits a characteristic of quasi-dyadic filter banks and that the frequency bandwidth is narrow at each scale. The energy distribution of the track irregularity and corresponding wavelengths can be determined from MEMD-based scalograms at different scales. In the sample track irregularity data,the energy of the gauge and cross level is mainly distributed in the medium and long wavelength frequencies. The energy of the alignment and profile is concentrated in the wavelengths between 4 and 36 m,and the energy of the twist is distributed in two wavelengths of 4. 9 m and 7. 6 m.%高速铁路轨道不平顺测量值是由许多不同频率、不同幅值的单分量信号叠加而成的复杂随机过程.为分析轨道不平顺在空间域和频率域的分布特性,利用希尔伯特-黄变换方法提取轨道不平顺在时-频域的能量分布,为从幅值和波长两个方面综合评价轨道几何状态提供一种新的分析方法.首先,利用多元经验模态分解基于数据驱动的滤波特性,将轨道不平顺数据同时分解为不同尺度下的幅值-频率调制的多元本征模态函数;然后,通过希尔伯特变换计算各尺度下本征模态函数的瞬时频率,分析各层本征模态函数的频率和能量分布特征.通过对轨道检查车的实测轨道不平顺数据解算与分析表明:轨道不平顺的频率分布呈现出近似二进滤波特性,并且每个尺度下的频率带宽较窄;多元经验模态分解尺度图能确定轨道不平顺在各尺度下的能量分布及对应的波长特征;样本轨道不平顺数据中,轨距和水平不平顺的能量主要分布在中长波波段,轨向和高低的能量主要集中在空间波长4～36 m范围;扭曲的能量分布在波长为4. 9 m和7. 6 m的两个尺度内.
  • 摘要：为建立更加简单的换道决策模型和考虑换道车辆和目标车道车辆间的相互作用,在换道效用和安全间隙选择的传统方法基础上,将社会力跟驰模型与换道模型相结合,提出了一种基于社会力的驾驶员主动换道决策行为模型.首先,以社会力模型中跟驰力作为各车道运行效用函数,构建换道目标车道选择效用模型;其次,考虑换道过程车辆纵向安全性,利用跟驰力搭建换道车辆和目标车道车辆间相互作用效用模型以对安全间隙选择进行约束;最后,对所建立的模型利用 NGSIM(next generation simulation)数据和 MATLAB遗传算法工具箱中genetic algorithm函数对多车道下驾驶员换道决策行为(不换道、向右换道、向左换道)进行标定和验证.研究结果表明:基于社会力的主动换道决策模型能够很好地识别出驾驶员的换道决策行为,最优参数在标定数据中对不换道、向右换道、向左换道的识别率分别达到了93. 44%、93. 14%和90. 77%,验证数据中换道决策行为识别率分别达到了86. 16%、80. 00%和80. 27%;标定和验证的单个识别率都在80. 00%以上,整体识别率分别达到92. 66%和83. 28%.%In order to establish a simpler lane-changing decision-making model and consider the interaction between the lane-changing vehicle and the vehicles of the target lane,on the basis of the traditional methods of lane-changing utility and selection of safety gap,an initiative lane-changing decision-making model for drivers based on the social model by combining the social force following model with the lane-changing model was proposed. First,taking the following force in the social force model as the utility function of each driveway,a lane-changing decision-making utility model for the target lane selection was established. Second,considering the vehicle's longitudinal safety in the lane-changing process,the following force was used to build utility model of interaction between the lane-changing vehicle and the vehicles of the target lane to constrain the selection of safety gap. Finally,the proposed model was calibrated and validated by using next generation simulation (NGSIM)data and genetic algorithm function in MATLAB genetic algorithms toolbox for drivers' lane-changing decision-making behaviours (keeping following,changing to right lane,changing to left lane ). The study results show that the lane-changing decision-making model based on social force could identify accurately the drivers'initiative lane-changing decision-making behaviour. The recognition rates of the optimal parameters in calibration data for drivers' lane-changing decision-making behaviours (keeping following,changing to right lane,changing to left lane)reached 93. 44%,93. 14%,and 90. 77%, respectively,and the recognition rates of the lane-changing decision-making behaviours in calibration data reached 86. 16%,80. 00%,and 80. 27%. Each recognition rate in calibration data and validation data was above 80. 00%,and the overall recognition rates reached 92. 66% and 83. 28%, respectively.
  • 摘要：To enhance slider flying stability and extend the life span of hard-disk drives,a molecular dynamics model for investigating lubricant transfer in the presence of slider lubricant contact was built. The effects of the following parameters on lubricant transfer and lubricant distribution on the disk surface during the operation of the hard-disk drive were analysed:relative velocity between the slider and disk and the range of the air-bearing pressure difference between the high-and low-pressure areas before contact. In addition,lubricant fragments with different lengths were obtained by adjusting the number of beads within a full lubricant molecule. The effect of lubricant fragments on lubricant transfer was also investigated. The simulation results indicate that the amount of lubricant transfer increases with increasing slider-to-disk relative velocity and air-bearing pressure difference;the growth rates of the amount of lubricant transfer are 38. 8% and 6. 7% for unit air-bearing pressure and unit velocity, respectively. Lubricant fragments have little effect on lubricant transfer;the height of lubricant accumulation decreases with increasing relative velocity. The lubricant accumulation height on the disk surface is not affected by the air-bearing pressure difference.%为了提高磁头飞行稳定性,增加硬盘使用寿命,基于分子动力学方法建立了磁头磁盘接触状态下的润滑剂迁移模型.根据硬盘工作时磁头磁盘的相对移动速度及磁头在盘片表面飞行时高、低压区域压力差的范围,采用所建立模型分析了相对移动速度及高、低压区域压力差对润滑剂迁移及在盘片表面分布的影响;此外,通过调节模型中单个润滑剂分子的粒子数得到不同长度的润滑剂分子碎片,并分析润滑剂分子碎片对润滑剂迁移的影响.研究结果表明:磁头磁盘之间的润滑剂转移随着相对移动速度及高、低压区域之间压力差的增大而增大.润滑剂转移量在单位压力及单位速度下的增长率分别约为38. 8%和6. 7%;润滑剂分子碎片对磁头磁盘之间的润滑剂转移影响很小;润滑剂在盘片表面堆积的高度随着磁头磁盘相对移动速度的增加而降低;高、低压区压力差的变化对润滑剂在盘片表面堆积的高度没有影响.
  • 摘要：In order to improve the quality of railway-turnout maintenance procedures and reduce equipment failure,a method for turnout-fault-detection and health-index evaluation based on the support vector domain description (SVDD)technique,is proposed. Through analysis of the switch-equipment mechanism,the turnout power curve was divided into 3 parts,each representing the unlocking,conversion,and locking processes respectively. To this end,characteristic parameters of the switch power curve were extracted. Subsequently,in the feature space,an SVDD-based turnout-fault-detection algorithm and health assessment were proposed. Lastly,the efficiency of the proposed algorithm was verified by comparing simulation results against experimental data. Experimental results demonstrate that the proposed health index possesses an accuracy of 95%,which could prove to be significant in on-site maintenance and guidance applications.%为更加精准地提高现场道岔维护质量,减少设备故障,提出了基于支持向量描述(support vector domain description,SVDD)的道岔转换故障检测和健康指标评估方法.首先,通过对道岔设备的动作机理分析,将道岔功率曲线分为3个动作过程:解锁过程,转换过程,锁闭过程,每一过程分别提取道岔功率曲线相应的特征参数;然后,在此特征空间上,设计了基于SVDD的道岔故障检测算法和健康评估算法,从而实现对道岔设备的健康管理;最后,利用道岔系统数学模型仿真数据和现场采集的道岔真实监测数据,对提出的算法有效性进行验证.实验表明,用本文提出的健康指标检测道岔故障和评估道岔健康状态的准确率达95%以上,对现场道岔维护有很大指导意义.
  • 摘要：为探究铁路大跨T形刚构桥车桥耦合振动特性与动力性能,以宜万铁路马水河大桥为工程背景,建立桥梁空间杆系有限元模型以及包含31个自由度的车辆模型,进行车桥耦合振动计算分析.通过动载试验测试桥梁的自振特性,并测试列车以不同速度通过桥跨和以一定速度在特定位置制动时桥跨结构的动应变、动位移以及加速度等动力响应.依据动载试验与车桥耦合振动计算综合分析马水河大桥的动力性能.研究结果表明:车桥耦合振动计算结果与实测结果吻合较好,桥梁结构动力响应满足规范限值,该桥具有良好的横向、竖向刚度与动力性能;实测桥跨结构及墩顶动力系数最大值为1. 08,桥梁结构受行车及制动的动力作用不明显;列车的动力响应随车速的提高而增大,但均满足规范限值,具有良好的安全性与平稳性.%To study the characteristics of coupled train-bridge vibration and dynamic performance of a long-span T-shaped rigid frame railway bridge,taking the Mashuihe bridge on the Yichang-Wanzhou railway line as an example,a three-dimensional finite element model for coupled train-bridge vibrations was built,and each carriage of a train was modelled by a 31-degrees-of-freedom dynamic system. Field tests were conducted to determine the free vibration characteristics as well as the strain,displacement, and acceleration of the bridge structure under trains moving at different speeds and braking at a specified position from a set speed. Therefore,the dynamic responses of the Mashuihe bridge was studied comprehensively,both numerically and experimentally. The calculated results were in good agreement with the corresponding experimental results. The dynamic responses of the bridge satisfied the requirements of the code,and the bridge exhibited good lateral and vertical stiffness. The dynamic coefficients of the mid-span and the top of the pier was 1. 08,which indicates that the impact of train braking has little effect on the bridge structure. The dynamic responses of the carriages increased with increasing speed,but also satisfied the requirements of the code. The carriages exhibited satisfactory safety and stability.
  • 摘要：为研究跨海桥梁施工过程中围堰周围海床的局部冲刷深度与冲刷坑形态,运用有限差分软件Flow-3D建立了水流作用下哑铃型围堰周围海床冲刷的三维数值模型.对新建模型的精度进行了验证,基于此模型研究了哑铃型围堰周围的流场特征及吃水深度、流速对围堰周围海床局部冲刷深度的影响.研究结果表明:受围堰与钢护筒影响,围堰周围流场特征比较紊乱;随着吃水深度与流速的增加,哑铃型围堰周围海床的冲刷深度逐渐增大,当吃水深度为12. 88 m,流速大小为4 m/s时,围堰周围最大冲刷深度接近8 m,然而与流速相比,吃水深度对哑铃型围堰周围海床冲刷深度的影响相对较小,围堰吃水深度由6. 88 m增加到15. 88 m时,最大冲刷深度增加不超过25%;最大冲刷深度发生在靠近围堰中心线的钢护筒附近;冲刷坑平面形态与围堰形状类似,围堰周围海床冲刷范围受流速影响较大,而受围堰吃水深度影响较小.%To investigate the local scour around a cofferdam,a three-dimensional numerical model for current-induced sediment scour around a dumbbell-shaped steel suspending cofferdam was established. After its validation using previous experimental data,the proposed model was applied to explore the local scour around dumbbell-shaped steel suspending cofferdams under various conditions. The numerical results indicate that the flow field distribution around the cofferdam is very complex owing to the mutual influence of the cofferdam and the steel casings. In addition,the maximum scour depth occurs around the casing adjacent to the centreline of the cofferdam,which increases with increasing current velocity and draught;the scour plain patterns are similar to the shape of the cofferdam. The results of this study can provide new evidence for studies of soil stability,and can also provide a reference for predicting the scour pattern around coastal structures.
  • 摘要：随着车辆的运行,车轮踏面会出现不同程度的磨耗,为研究磨耗状态下车轮与钢轨之间的静态匹配性能,利用轮轨接触几何关系和非赫兹滚动接触理论,计算不同磨耗程度的车轮对轮轨接触几何参数和接触力学特性的影响,并与CHN60钢轨的计算结果进行对比.分析结果表明:轮对横移小于4 mm时,车轮磨耗程度越大,车轮上接触点的横向分布宽度越大,60N钢轨的接触点横向分布宽度明显小于CHN60钢轨,对提高车辆运行稳定性有利;车轮磨耗程度越大,轮轨磨耗指数越大,60N钢轨的轮轨磨耗指数较小,有利于轮轨廓形的保持能力.车轮磨耗程度越大,位于表面滚动接触疲劳区的范围越大,相比CHN60钢轨,60N钢轨位于表面滚动接触疲劳区的情况较少,相同条件下,能够减少轮轨滚动接触疲劳伤损的发生.%Over time,the running of vehicles results in different degrees of wear on the wheel treads. To study the static matching characteristics between the worn wheel and the rail,the wheel-rail contact geometry relationship and non-Hertz rolling contact theory were used to analyse the effects of worn-wheel profiles on the wheel-rail contact geometry parameters and contact behaviour. The results were compared with those of CHN60 rail and analysed. The results indicate that when the lateral displacement of the wheel set is less than 4 mm,the degree of wear on the wheel is greater,and the lateral distribution width of wheel-rail contact points on the wheel is larger. The lateral distribution width of the wheel-rail contact points of 60N rail is significantly less than that of the CHN60 rail, thereby improving the vehicle's running stability. The wheel-rail wear index increases with the degree of wheel wear. The wheel-rail wear index of 60N rail is smaller,which improves the ability to maintain the wheel-rail profile. A greater degree of wheel wear corresponds to a greater surface rolling contact fatigue area. Compared with CHN60 rail,the number of cases located in the area of surface rolling contact fatigue of 60N rail is less,which can reduce the rolling contact fatigue damage under the same conditions.
  • 摘要：In order to improve the maintenance abilities of high speed railway and reduce train delays, an evaluation system is proposed based on actual maintenance plan data. Evaluation of the railway maintenance plan is supposed to identify any weak links and contribute to the safety of the operational environment. In this system,four key maintenance plan factors are identified:power supply,control system equipment,station infrastructure,and signal and communication equipment. The triangular fuzzy number and a fuzzy evaluation method are introduced to build an importance scale matrix for estimating the importance of these four factors in maintenance plans. Delays caused by equipment and infrastructure failures are extracted and combined based on real delayed train data. These factors are also proved to be independent. Factors causing delays and the number of delayed trains are used to quantitatively measure the effects of maintenance plan factors. Finally,maintenance plan data and delayed train data from the China Railway Company are used to verify the feasibility of the method. Results show that implementing a daily HSR maintenance plan has a positive effect on decreasing train delays. The amount of attention focused on the maintenance factors is inversely proportional to the delay situation. Maintenance of control equipment and power supply equipment is weak,which is the primary cause of train delays.%为提升高速铁路施工维修水平,减少列车运行延误,对施工计划的具体内容进行效果评价,能找出检修内容的薄弱环节,从而保证高铁设施设备质量状态及列车安全稳定的运行.以实际施工计划数据为基础,对现场施工计划进行影响因子提取,建立基于供电、控制设备、车站及线路及信号及通信设备等重点检修项目内容的评价体系;引入三角模糊数和模糊评价模型,建立施工项目内容的重要度判别矩阵,判断各因子在天窗施工计划中受到重视的程度;分析实际列车延误数据,提取合并与设备故障相关的延误致因,并证明了合并后因子间的独立性;以施工计划实施后仍产生的各类型设备故障及其导致的延误列车数为指标,评价施工计划项目实施效果;最后,以某铁路局实际天窗施工计划内容、列车延误数据为实例.研究结果表明:施工维修项目重视度与设备故障导致的列车运行延误数量、晚点程度成反比;对控制设备和供电设备的检修较为薄弱,这类设备的故障是列车运行延误和晚点多发源.
  • 摘要：针对高铁以及山区环境下正交频分复用(orthogonal frequency division multiplexing,OFDM)通信系统的信道估计问题,提出一种基于卡尔曼滤波的快时变稀疏信道估计方法.该方法基于快时变信道的基扩展模型(basic expansion model,BEM),应用压缩感知(compressed sensing,CS)理论进行稀疏时延估计,并应用卡尔曼滤波(Kalman filter,KF)技术对BEM系数进行估计,进而获得信道增益.仿真结果表明,在相同信噪比(signal to noise ratio,SNR)条件下,随着归一化多普勒频移(frequency-normalized Doppler shift,FND)增大,新方法的信道估计均方差(mean square error,MSE)性能优于传统方法,如当SNR为20 dB,FND为0. 1时,新方法较传统方法性能提升了4 dB,表明对信道时变性具有更优的鲁棒性;在相同的多普勒频移条件下,随着SNR增加,各方法的均方差均有所改善,新方法改善更明显,如当FND为0. 2时,在信道估计均方差为0. 06的条件下,新方法较传统方法获得了6 dB的信噪比增益,表明对抗信道噪声能力更强.%A fast time-varying sparse channel estimation method based on the Kalman filter is proposed for channel estimation of an orthogonal frequency division multiplexing communication system operating in high-speed railways and mountain areas. Based on the basic expansion model (BEM), compressed sensing (CS)was employed for the estimation of sparse delays,and a Kalman filter (KF) estimator was utilised for estimating the BEM coefficients. The channel gains were then computed easily. The simulation results show that under the same signal-to-ratio (SNR)condition,with the increase in frequency-normalised Doppler shift (FND),the MSE of the new method is superior to that of traditional methods,such as SNR is 20 dB and FND is 0. 1,and a 4 dB performance improvement is achieved. Under the same Doppler shift condition,the same result is obtained as that with the increase in SNR,such as FND is 0. 2 and MSE is 0. 06,and a 6 dB SNR gain is achieved. These results show that the new method is more robust to variation in channel time and stronger against noise compared with traditional methods.
  • 摘要：To study the effect of initial deflection imperfection on the flutter critical dynamic pressure of a cylindrical shallow shell aeroelastic system,an initial deflection was introduced into the aeroelastic equation of cylindrical shallow shells. The differential quadrature method was used to discretize the system,and the flutter critical dynamic pressure of a linear system in supersonic axial flow was analysed using the eigenvalue method. The results showed that the initial deflection imperfection can significantly affect the flutter critical dynamic pressure. Herein,when the circumferential half wave number of the initial deflection equals 1,the critical dynamic pressure parameter of flutter is proportional to the initial deflection imperfection factor. When the circumferential half wave number is less than 4,with the increase in the initial deflection imperfection factor,the critical dynamic pressure of the system tends to decrease. For the small curvature condition,when the circumferential half wave number is greater than 4,the flutter critical dynamic pressure change caused by the increase in the initial deflection imperfection factor is not significant. For the large curvature condition,when the circumferential half wave number is greater than 4,the flutter critical dynamic pressure decreases significantly with the increase in the initial deflection imperfection factor. It was also found that the geometric form of the initial deflection affected the circumferential half wave number of the flutter coupling modes.%为研究初始挠度缺陷对圆柱形扁壳气动弹性系统颤振临界动压的影响,将初始挠度引入圆柱形扁壳气动弹性方程,采用微分求积法进行离散,运用特征值方法分析了线性系统在超声速轴向流中的颤振临界动压.研究结果表明,初始挠度缺陷会显著影响颤振临界动压.在本文计算参数下,当初始挠度周向半波数等于1时,颤振临界动压参数与初始挠度缺陷因子成比例关系;当周向半波数小于4时,随着初始挠度缺陷因子的增加,系统颤振临界动压大都呈现减小趋势;对于小曲率情况,当周向半波数大于4时,初始挠度缺陷因子的增加带来的颤振临界动压变化并不显著;对于大曲率情况,当周向半波数大于4时,随着初始挠度缺陷因子的增加系统颤振临界动压显著减小;初始挠度的形式会影响产生耦合模态颤振的周向半波数.
  • 摘要：为了研究全钢管混凝土框架结构的抗震性能,对一榀单跨3层方钢管混凝土柱-矩形钢管混凝土梁框架结构进行拟静力试验,研究了该结构的滞回性能、延性、承载力与刚度退化、耗能能力等性能指标,并通过有限元模拟,分析了矩形钢管混凝土梁的受力机理.研究结果表明:此类全钢管混凝土框架结构滞回曲线饱满,延性系数大于3,层间位移转角在1/43～1/27之间,层间塑性变形能力随着框架柱长细比及梁柱线刚度比的增加逐渐减小,等效粘滞阻尼系数在0.115 ～0.441之间,强度退化不明显,但刚度退化较为明显;在加载过程中,梁端、柱根部屈服后,随着荷载的增加,中和轴向受压区逐渐移动,极限荷载时混凝土受拉区达到最大.%To study the seismic performance of concrete-filled steel tubular(CFST) frame structure,the quasi-static test on a three-story frame structure consisting of square CFST column and rectangular CFST beam was carried out.The hysteretic behavior,ductility,bearing capacity,stiffness degradation,energy dissipation capacity and other performance indicators were studied,and finite element simulation was used to analyze the mechanical behavior of concrete-filled rectangular steel tubular beams.Results show that the hysteretic curve of concrete-filled steel tubular frame structure is plump.Its ductility coefficient is greater than 3.The inter-story drift ratio falls in the range of 1/43 to 1/27.The inter-story plastic deformation capacity decreases with the increase of slenderness ratio of frame column and the stiffness ratio of the beam and column.The equivalent viscous damping coefficient is within the range of 0.115 to 0.441.The strength degradation is not obvious,but the stiffness degradation is more obvious.With the increase of load,if the beam or column yields,the neutral axis gradually moves to compressive zone;and the tension zone of concrete reaches the maximum area when load reaches the maximum.
  • 摘要：为研究风场特性及矩形断面长宽比等因素对矩形高层建筑脉动风荷载功率谱特性的影响,以矩形断面(宽厚比B/D =2∶1,1∶2)为例,采用刚性模型测压风洞试验的方法,测得了边界层中矩形模型的脉动风荷载时程.参考日本建筑设计建议(AIJ)给出的横风向脉动风荷载谱模型,对试验结果进行拟合,给出了一个简化的矩形高层建筑横风向脉动风荷载功率谱函数表达式.试验结果表明,顺风向脉动风荷载主要由纵向紊流引起,其功率谱密度函数特征与来流紊流基本一致;横风向脉动风荷载的形成机理较为复杂,矩形断面侧边存在复杂的分离流动及再附现象,但其无量纲功率谱密度沿高度基本一致;斯托哈尔数沿高度方向变化较小,当宽厚比分别为2∶1和1∶2时,斯托哈尔数分别约为0.128和0.069 7.%In order to study the effects of wind field characteristics and side ratio of rectangular section on the spectral characteristics of fluctuating wind loads for rectangular high-rise buildings,the pressure fluctuations on a stationary rigid model with cross configurations of 1 ∶ 2 and 2∶ 1 were measured by wind tunnel test for synchronous pressure measurement in simulated atmospheric boundary layer.Referring to the spectral model given by the Architectural Institute of Japan (AIJ),a simplified spectral expression of fluctuating across-wind loading of rectangular high-rise building was proposed by fitting the measured results.The experimental results show that the fluctuating along-wind load is mainly caused by longitudinal turbulence,and the spectrum of fluctuating along-wind load is consistent with those of incident turbulence.The formation mechanism of fluctuating across-wind loads is more complex,and there is vortex shedding,separation or reattachment on the sides of the rectangular prism.The dimensionless power spectral density and the Strouhal numbers are almost constant along the height.The values of Strouhal number are 0.128 and 0.069 7 respectively for the side ratios of 2∶1 and 1:2.
  • 摘要：为深入探索有砟道床阻力演变对桥上无缝线路力学行为的影响,针对路基地段与桥上道床纵、横向阻力开展试验研究.以一座铁路常用双线特大连续梁桥为例,获得了桥上线路阻力分布特征,并提出实际道床在服役过程中存在局部阻力退化现象.在此基础上,建立了可考虑道床阻力非均匀分布与退化效应的桥上无缝线路纵向力学行为分析模型,开展了道床阻力分布及退化对大跨桥上无缝线路力学行为的影响分析.研究结果表明:桥上道床纵向阻力区域分布差异显著,桥跨中部纵向阻力值最大,阻力值为31.8 kN/枕,梁缝附近道床纵向阻力相对较小,阻力值为21.7 kN/枕,阻力退化效应明显;桥上道床横向阻力分布同样表现出一定区域分布特征,但退化效应并不明显,桥跨中部与梁缝处阻力值分别为31.7、25.5 kN/枕;由于受到温度荷载作用下梁体伸缩、列车动荷载作用下桥梁产生振动变位和梁端转角的影响,散休道床始终处于拉伸压缩的动态变化过程中,道床阻力表现出明显的退化特性;考虑道床阻力退化效应时,温度荷载作用下的钢轨伸缩附加力、钢轨位移、梁轨相对位移值有一定衰减,当桥梁温度跨度为140 m时,钢轨纵向附加力最大值减小约11.7％,且衰减率随着温度跨度的增加近似呈线性增长,按现有规范计算方法得到的梁轨相互作用结果偏大.%In order to explore the effect of ballast resistance evolution on the mechanical behavior of the continuously welded rail (CWR) on bridge,tests were conducted for the longitudinal and lateral ballast resistances on bridge and roadbed sections.Taking an example of an extra-large double-line continuous beam bridge commonly used in railway,the track resistance distribution characteristics on bridge were obtained,and the local ballast resistance degradation was discovered in the ballast service.On this basis,the longitudinal mechanics behavior model of CWR on bridge was established,which takes into account the non-uniform distribution and degradation of ballast resistance.The results show that the distribution of ballast longitudinal resistance on bridge shows significant regional distribution characteristics,the maximum longitudinal resistance was 31.8 kN per sleeper at the central span of bridge,and the longitudinal resistance near the beam joint was relatively small,21.7 kN per sleeper,demonstrating obvious ballast resistance degradation.The lateral resistance distribution on bridge also has moderate regional distribution characteristics,the lateral resistance at the central span of bridge was 31.7 kN per sleeper and the lateral resistance near the beam joint was 25.5 kN per sleeper,while the degradation does not obvious.As thermal load leads to beam expansions and the dynamic loads of trains cause bridge vibration displacement and rotation angles at the beam support,the crushed-stone ballast dynamically changes between tension and compression,and the ballast resistance shows obvious degradation characteristics.When there is ballast resistance degradation,the rail longitudinal force,rail displacement and relative displacement between bridge and track under thermal loading has a certain attenuation.Thus,the maximum rail longitudinal additional force with the temperature span of 140 m was reduced by about 11.7％,and the attenuation rate increases linearly with the increase of temperature span.The beam-rail interaction is relatively large if it is calculated according to specifications.
  • 摘要：In order to develop new time integration algorithms,a generalized multi-step explicit integration method (GMEM) was proposed by means of weighting independent variables,accelerations.Firstly,a general integration format was provided based on the acceleration explicit method.Furthermore,the stability,numerical dissipation,numerical dispersion and accuracy were analyzed.Finally,two numerical examples were employed to contrastively analyze three kinds of GMEMs (GMEM1,GMEM2 and GMEM3-2),the HHT-α method and the Newmark method.The results indicate that the GMEM is conditionally stable.The spectral radius is identically equal to 1 in the system without damping.The GMEM of three steps can achieve the highest accuracy of three order.There is not numerical dissipation for the GMEM of three steps in undamped systems.The root mean square error of the GMEM2 is approximately half of that of the Newmark method,and 1.8 times that of the GMEM3-2 approximately.%为了开发新的时间积分算法,通过对独立变量加速度的加权,提出了广义多步显式积分算法(GMEM).首先,在加速度显式法的基础上给出了通用的积分格式;其次,分析了所提算法的稳定性、数值耗散、数值色散和精度;最后,通过2个算例对3个广义多步显式积分算法(GMEM1、GMEM2和GMEM3-2)以及HHT-α法和Newmark法进行了对比分析.分析结果表明:本文所提算法是条件稳定的,在无阻尼系统中谱半径恒等于1;3步广义多步显式法最高具有3阶精度,在无阻尼系统中不存在数值耗散;GMEM2的均方根误差约为Newmark法的1/2,约为GMEM34的1.8倍.
  • 摘要：针对飞机转弯过程中机轮对道面产生显著的附加水平剪切作用,加重柔性道面轮辙病害影响行驶安全问题,基于ABAQUS软件平台建立了连续变温沥青道面温度场与轮辙分析模型.该模型开展了机轮低速地面转弯特性分析,对比了跑道直线段与转弯区轮辙形成规律,提出了适用于转弯区道面变形特征的轮辙评价指标,对交通荷载条件和环境气象条件进行了参数影响分析.研究结果表明:机轮法向侧推力在道面面层底部产生横向拉伸变形,轮载作用位置竖向应力水平低于直线段,与轮辙凹陷深度规律一致;外侧机轮隆起变形幅度增加,内侧机轮隆起变形削弱并与轮迹凹陷盆连为整体;道面综合轮辙深度随转弯速度增加而增加,增幅为50％;轮载累积作用时间随转弯速度增加而缩短,轮迹带下陷变形明显减小,最大降幅达到30％;沥青混凝土面层日间持续高温是道面轮辙初始阶段快速发展的重要条件,表层轮辙敏感温度在30℃附近;通过控制高温时段飞机最低转弯滑行速度有利于降低该区域轮辙变形幅度.%Since the lateral shearing effect of aircraft wheels during low-speed turning may aggravate the rutting defects of flexible pavement and jeopardize the driving safety,a numerical analysis model of flexible pavement structure coupled with a continuous alternating temperature field was established on the ABAQUS platform.In this model,the low speed turning performance of aircraft wheel on the ground was formulated and analyzed,and the laws of rutting formation in straight-line and turning areas of flexible pavement were compared.According to the deformation characteristics of pavement in turning area,a new evaluation index of rutting depth was proposed,whereby parametrical influences of traffic load and meteorological conditions on the rutting formation were analyzed.The results indicate that the transverse thrust of aircraft wheel load will lead to a notable lateral tensile deformation at the bottom of the pavement surface layer.The vertical stress at the loading position in the turning area is smaller than in the straight line area,which is in good accordance with the distribution of rutting depth.As the upheaval deformation at the external side of the outside wheel increases in the turning area,the upheaval deformation at the internal side of the inside wheel decreases and merges with the settlement basin together.The deformation can be reflected by the index of composite rutting depth and it presents a tendency to increase with the aircraft's turning speed,with a maximum amplification of nearly 50％.With the turning speed increasing,the accumulative action time of wheel load shortens,and the rutting depth at wheel marks decreases with a maximum amplitude of 30％.In addition,the continuous high temperature of surface layer of flexible pavement during daytime is a vital environmental reason for the rapid development of rutting formation in the initial stage.The sensitive temperature of rutting formation in the flexible pavement under study is around 30℃.The rutting deformation of the turning area can be remarkably reduced by limiting the minimum taxiing speed in high temperature conditions.
  • 摘要：To analyze load reduction performance of buried pipes reinforced by geogrids,the influence of embedment depth of the uppermost geogrid,length of geogrid,geogrid layers,sand surrounding buried pipes and buried depth of pipes on the deformation and mechanism of pipes was studied through static loading plate tests.The results show that when the length of geogrids changes from 0 to 4D (D denotes the external diameter of pipes),relative density of sand varies from 45％ to 75％ and reinforcement layers change from 0 to 3 or 4,the ultimate bearing capacities of load plate are respectively 1.4,1.6 and 2.52 times the one without reinforcement.Moreover,the hoop strain plays a dominant role in buried pipes,ranging from-1.0％ to 0.5％.Deformation in vertical direction is greater than that in horizontal direction.The optimal load reduction performance of pipes reinforced by geogrids was obtained when the embedment depth of the uppermost geogrid is 0.4B (B is width of loading plate),geogrid length is 4D,and geogrid layers is 3-4.%为了深入分析土工格栅加筋防护对埋地管道的减载性能,采用埋地管道上方地表加载板静载试验,综合对比研究了筋材首层埋深、铺设长度与层数及管周土性质和管道埋深等因素对管道变形和力学性能的影响.研究结果表明:当筋材长度由0增至4D(D为管道外径)、管周土密实度由45％增至75％、加筋层数由0增至3～4层时,管道上方加载板极限承载力相应地分别增加1.40倍、1.60倍和2.52倍;管道以环向应变为主,应变范围在-1.0％～0.5％之间;相同条件下管道垂直径向变形大于水平径向变形,且当筋材首层埋深为0.4B(B为加载板宽)、筋材长度为4D和筋材层数为3～4时,土工格栅加筋减载防护性能最佳.
  • 摘要：针对盾构隧道施工过程中带榫管片易出现裂纹及局部破损的现象,运用ABAQUS中的扩展有限单元法,建立了标准带榫管片的数值模型,并针对管片受力不均、千斤顶加压不同步和千斤顶偏心荷载3种不良施工荷载情况下的12个具体工况,对施工过程中带榫管片裂纹初始开裂位置、扩展方向及裂纹空间分布规律等进行了系统分析.研究结果表明:不良施工荷载是带榫管片产生裂纹的主要因素,荷载大的位置易产生裂纹,千斤顶先接触部位易产生裂纹;带榫管片凸榫端中部较两端易产生裂纹,带榫管片内弧面较外弧面更易产生裂纹;3种不良施工荷载对带榫管片的损害程度由强到弱依次为千斤顶偏心荷载、千斤顶加压不同步和管片受力不均.%To explore the cracking and local damage of tenon segment that easily occurs during the construction of shield-driven tunnels,a model of standard tenon segment was built using the extend finite element method (XFEM) with ABAQUS.The initiation location,propagation direction and distribution of segment cracks were analyzed in a dozen of working conditions including non-uniform jacking forces,asynchronous jacking and eccentric jacking loads.Numerical results indicate that bad construction load is the main cause of cracks.Areas burden with large loads and that the jacks first contact are liable to crack.Cracks are easier to initiate and propagate at the central area of the top surface of segment than at both ends,and at the intrados than at outer surface.Three factors,if sorted in a descending order by their damage severity to a tenon segment,are eccentric jacking loads,asynchronous jacking and non-uniform jacking forces.
  • 摘要：为了提高机车车辆碰撞试验台的驱动能量,提出气囊自增长可变边界,实现了高压气体在约束且不爆破条件下长距离弹射做功.基于控制体积法,利用LS-PrePost和LS-DYNA软件建立环形折叠气囊的弹射模型,在初始压缩和一定压力条件下,研究多节气囊的受压弹射过程和气囊构造特征对气囊弹射行为及能量的影响规律.研究结果表明:环形折叠气囊弹射模型能够反映气囊弹射加速方法的基本特性,气囊弹射加速持续并且稳定;气囊节数与弹射距离、能量输出大小和弹射试验台稳定性有关,气囊节数越多弹射作用距离越大、能量输出效果越显著,3节气囊弹射能量是1节气囊弹射能量的6倍;气囊节数越多气囊端部摆动量越大,但3节气囊弹射端部摆动量不超过7 mm,气囊弹射稳定性良好.%To solve the driving problem with great energy for a train collision testbed,the airbag with a self-growth variable boundary was proposed.The airbag with high-pressure gas can work effectively in a long distance under the condition of constraint and un-blasting.Based on the control volume method,an ejection model of the circlewise folding airbag was built using the simulation software LS-PrePost and LS-DYNA.The influence of the ejection process and structural features of multilevel airbags on the ejection behavior and energy was studied under conditions of initial compression and a certain pressure,respectively.The results show that the ejection model of the circlewise folding airbag can reflect the basic characteristics of the airbag ejection acceleration method,and the airbag ejection acceleration is stable and continuous.The number of airbags has a significant effect on the ejection distance,the output energy,and the stability of the airbag collision testbed.A more number of airbags means a greater ejection distance and more effective energy output.The energy of a three-airbag catapult is 6 times than that of a one-airbag catapult.The more the number of airbags is,the larger the lateral displacement of the airbag ends is.However,the swing displacement of a three-airbag catapult is not more than 7 mm,and hence a good stability can be ensured in the airbag ejection process.
  • 摘要：The divide-and-conquer strategy is adopted to improve the efficiency of 3D reconstruction of a single line drawing and guarantee the convergence of the optimization algorithm for polyhedral objects.First,the single line drawing is divided into a lot of closed polygons,then all closed polygons are grouped according to their connection relationships,and finally all faces represented by the closed polygons in one group are reconstructed into 3D.In this way,a normal global optimization problem is resolved in a step-by-step fashion.Based on this strategy,several local optimization criteria are discussed,and a step resolving algorithm for 3D reconstruction by use of the rotation transformation are proposed.By rotating the child face against its parent face until some local optimization criteria are met,all child faces in the same level can be resolved in 3D space.Utilizing the top-down linkage relationships among faces represented by the loops on the drawing,all the child faces will be reconstructed step by step.Case studies indicate that this method is suitable for 3D reconstruction of multi-face objects and the efficiency can be improved by 20％ compared with typical global optimization methods.%为了提高单幅线图的三维物体识别重建效率,并保证优化算法的收敛性,基于划整为零、分而治之的策略,首先把单幅线图划分为若干封闭线框,然后按其连接关系进行分组,随后针对各组线框所表征的面片进行三维重建计算,把一个整体优化问题转化为若干局部优化计算问题.在此基础上,分析构造了适用于局部优化识别重建的计算准则,提出了基于旋转变换的分步求解方法.通过子面片绕其父面作旋转变换,利用局部优化准则完成同级子面片的重建计算,根据线图中各线框表征的面片之间的级联关系逐级向下传递,实现全部面片三维重建.算例测试表明,本文方法适于多面体的三维重建,且平均计算效率较全局优化方法高出20％.

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