To study the impact of upwarp deformation in the ballastless track on the jumping behavior of the high-speed vehicle, utilizing UM and ANSYS joint simulation, a vertical vibration model of high-speed vehicle on CRTS II slab ballastless track was developed based on the non-Hertz wheel–rail contact model of virtual penetration theory. By using the single-wave cosine curve simulating the characteristics of upwarp deformation in the track slab, we calculated the whole process of wheel jumping. This allowed us to analyze how the amplitude and wavelength of the track slab upward deformation influence the vibration response of the vehicle–track system. Our findings indicate that when a wheel passes through the arch section of the track slab, the entire wheel jumping process consists of distinct stages: “wheel–rail bonding, wheel–rail separation, wheel–rail impact (one or more times), and wheel–rail bonding.” As the amplitude of upwarp deformation increases and the wavelength decreases, significant changes occur in several parameters, including the vertical force between the wheel and rail, wheel unloading rate, wheel jump height, frequency, duration, and vertical displacement of the rail. Additionally, when the wavelength is between 2 and 6[Formula: see text]m and the amplitude is 8[Formula: see text]mm, the vertical force between the wheel and rail becomes zero, the wheel load reduction rate is one, and the wheel jumps. When the wavelength is less than 3[Formula: see text]m, the wheel jump height exceeds the flange height, increasing the risk of derailment. Meanwhile, during the first wheel–rail impact, the wheel–rail vertical force and the rail vertical displacement reach their maximum, potentially impacting rail service performance negatively. Finally, compared to the amplitude of the track slab camber deformation, its wavelength has a greater impact on the entire process of wheel jumping. It is recommended that attention be paid to the change in the wavelength of the track slab camber during the maintenance and repair of the ballastless track.

针对西部铁路轨道基础不均匀沉降、路基冻胀及活动断裂带等特殊地段,采用ABAQUS有限元软件,建立聚氨酯固化道床轨道与双块式无砟轨道的计算模型,计算并分析在不均匀沉降、上拱及断层这3种基础变形作用下聚氨酯固化道床轨道和双块式无砟轨道这2种轨道结构的变形规律,同时,对比分析这2种轨道结构的维修特性.研究结果表明:相对于双块式无砟轨道,聚氨酯固化道床轨道对3种基础变形的跟随性更强,离缝现象出现的概率偏小,同时,离缝值也更小;对于工程及环境条件恶劣的西部铁路的维修作业,聚氨酯固化道床轨道具有更好的适应性.

基于货物列车-轨道-桥梁系统(FTTB系统)空间振动计算模型,将横风作用转化为构架蛇行波,建立横风作用下FTTB系统空间振动计算模型;根据列车脱轨能量随机分析方法,提出横风作用下重载铁路桥上列车脱轨全过程计算方法及列车脱轨预警原理;实现不同风速、车速下桥上列车脱轨全过程计算,分析横风对列车脱轨全过程的影响.结果表明:车速60～80 km/h、风速20.7～28.4 m/s时,车轮悬浮量均达到25 mm,列车脱轨;随着风速及车速的增大,脱轨系数、轮重减载率、转向架与钢轨横向相对位移、梁跨跨中及墩顶横向位移均增大明显;考虑安全系数1.25,得到不同车速、风速下转向架与钢轨横向相对位移预警阈值.上述结论可为研发横风作用下桥上列车脱轨预警装置提供理论依据和基础数据.

Aiming at the existing heavy‐haul railway, bridges hardly meet the transportation requirements. Based on the spatial vibration calculation model of the freight train–track–bridge (FTTB) system, the FTTB spatial vibration model under the condition of auxiliary steel beam reinforcement is established. Besides, according to the random analysis method of train derailment energy, coming up with an evaluation method of auxiliary steel beam reinforcement is based on safety and dynamic response, which is used to discuss the train safety and the change law of FTTB system vibration response. The results show that the derailment resistance of the FTTB system is increased by 22.6% after the auxiliary steel beam is reinforced. Compared with the previous speed (115.56 km/h), the speed is 132.73 km/h after the auxiliary steel beam reinforcement; at the same time, the allowable limit speed increases from 92.49 km/h to 106.18 km/h. In addition, the reinforcement of the auxiliary steel beam can not only effectively reduce the lateral vibration response of the FTTB system under the action of empty wagon but also effectively decline the vertical vibration response of the FTTB system under the action of the loaded wagon, which can meet the stability requirement for running at the speed of 90 km/h. In summary, the reinforcement of auxiliary steel beams can improve the running safety of trains, reduce the vibration response of the FTTB system, and meet the requirements of operation stability.

为研究提速及高速列车跳轨脱轨机理,提出跳轨车轮位移及轮轨力的基本特征,强调考虑轮轨冲击作用的必要性.在具体计算时,应包含3种完全不同的动力学控制方程,分别是轮轨密贴时的方程、轮轨分离时的方程和轮轨冲击时的方程.研究结果表明:本文方法从本质上揭示了列车车轮跳轨全过程,能够描述车轮跳轨的主要信息;速度越大,车轮跳轨高度越高,跳轨持续时间越长;是否考虑轮轨冲击作用,对于车体加速度、钢轨速度、钢轨加速度、轨枕速度及轨枕加速度等车-轨系统振动响应影响较大.

为研究客运列车因曲线超速引起的脱轨规律,基于列车-轨道系统空间振动计算模型,建立客运列车-曲线轨道系统空间振动计算模型.基于该模型,根据列车脱轨能量随机分析方法,提出客运列车曲线超速引起的脱轨全过程计算方法,计算不同曲线半径、外轨超高下列车超速引起的脱轨全过程,分析轮轨接触状态及其相对位置.研究结果表明:据脱轨系数和轮重减载率难以判定客运列车超速时是否脱轨;脱轨车辆位于编组前部,在脱轨前及时预警十分必要;随着曲线半径、外轨超高增大,列车脱轨速度随之增大,脱轨瞬间转向架与钢轨横向相对位移也随之增大;并考虑安全系数1.25,得到转向架与钢轨横向相对位移最大为60.2 mm,这可为研发客运列车曲线超速脱轨报警装置提供参考.

根据重载铁路货物列车-轨道系统(FTT系统)横向振动稳定性分析方法,提出基于货物列车抗脱轨安全度的重载铁路轨道结构强化措施评价方法,分析并量化提高钢轨等级、采用Ⅲ型轨枕、强化扣件及道床等轨道强化措施对货物列车抗脱轨安全度的影响.研究结果表明:与提高钢轨等级相比,采用Ⅲ型轨枕对列车抗脱轨能力、临界车速及容许极限车速的影响更大;强化扣件或道床均可大幅度提高列车抗脱轨能力、临界车速及容许极限车速,但当扣件和道床的横向刚度分别大于120 MN/m和15 MN/m时,货物列车抗脱轨安全度提升幅度较小;上述轨道强化措施均能改善行车平稳性,但强化道床对行车平稳性影响较小.轨道强化措施具有提高货物列车抗脱轨安全度的功能,且本文提出的评价方法能够反映列车抗脱轨信息,可为轨道强化措施的评价和制定提供参考.

为研究无缝线路钢轨鼓胀引起的脱轨规律,以"单波形"钢轨鼓胀为例,建立无缝线路钢轨鼓胀状态下货物列车-轨道系统空间振动计算模型;按照列车脱轨能量随机分析方法,提出无缝线路钢轨鼓胀引起的货物列车脱轨全过程计算方法,计算脱轨全过程,分析鼓胀状态对轮轨几何接触状态和相对位置的影响.研究结果表明:鼓胀波长一定时脱轨系数和轮重减载率随鼓胀幅值增大而增大,鼓胀幅值一定时脱轨系数和轮重减载率随鼓胀波长减小而增大,但脱轨系数和轮重减载率对脱轨缺乏控制作用;转向架与钢轨横向相对位移随鼓胀波长的减小或幅值的增大而增大,得到考虑工况下的最大值为72.6 mm.上述结果可为研发具有实时判别脱轨功能的检测装置提供基础数据.

国内刚性悬挂供电网线的使用,对受电弓弓网动态匹配性能及缓冲吸震性能提出了更高的要求.但国内各厂家受电弓使用性能差异大,部分项目受电弓使用过程中出现了较多的问题,导致受电弓使用故障率较高,各地铁公司对受电弓使用维护成本较大,部分地铁公司对既有项目使用的受电弓提出了换型要求.现以国内某地铁项目为例,从受电弓技术参数、机械接口和电连接接口、电气性能及限界等方面,对所替换受电弓如何保证能够适用于既有项目进行了剖析.

基于有限单元法及混凝土塑性损伤模型,建立路基上单元板式无砟轨道静力分析模型,研究路基冻胀—融化—沉降循环作用下,无砟轨道结构的受力和变形特性及伤损演化规律.研究结果表明:在路基冻胀—融化—沉降循环作用下,轨道板和底座板在冻胀过程中逐渐形成塑性损伤,且轨道板的塑性损伤早于底座板的塑性损伤;在融化回落及沉降阶段,轨道板的损伤状态相对稳定,而底座板在距其端部1/3位置处逐渐形成第二塑性区;在路基冻胀—融化—沉降循环作用下,将不可避免地引起轨道不平顺,轨道不平顺幅值呈增加—减小—反向增加的变化趋势;当路基回落至初始状态时,轨道结构存在部分残余变形;底座板与基床表层间的离缝呈张开—闭合—张开的循环性变化规律.该研究可为高速铁路无砟轨道养护维修提供参考.

针对路基上CRTS Ⅰ和CRTSⅡ型板式无砟轨道的结构特点,分别建立了相应的有限元模型,研究了路基不均匀沉降作用下不同板式无砟轨道受力与变形的传递规律及其影响.分析结果表明:路基不均匀沉降发生后,上部轨道结构的垂向变形具有一定跟随性,变形与沉降曲线相近但不完全重合;底座板伸缩缝的存在对轨道结构的受力和变形有较大影响,在20 mm/20 m沉降条件下,CRTS Ⅰ、CRTSⅡ型板的垂向位移分别达沉降幅值的90％和60％,相对CRTS Ⅰ型板而言,沉降对CRTSⅡ型板的垂向位移影响较小,但后者更易形成较大范围的离缝,离缝长度达6.52m,为CRTS Ⅰ型板离缝长度的1.92倍;当沉降幅值位于底座板中心时,离缝主要集中在伸缩缝、沉降端部和沉降中心,但当沉降幅值位于伸缩缝处时,离缝主要集中在伸缩缝两侧和沉降端部;沉降波长或幅值改变时,会导致最大离缝位置出现偏移;在路基不均匀沉降作用下,CRTS Ⅰ型板的底座板纵向最大拉应力均大于轨道板的纵向最大拉应力,而CRTSⅡ型板的情形则相反;从混凝土强度考虑,CRTS Ⅰ型板沉降控制标准应以底座板的拉应力控制为主,而CRTSⅡ型板应以轨道板和底座板的拉应力综合控制.

为研究高速铁路无砟轨道扣件系统中的弹条部件断裂原因,以WJ-7型扣件为研究对象,建立扣件系统有限元实体模型,分析扣件安装、车轮多边形磨耗及曲线线型等3种条件下的扣件弹条力学特征.研究结果表明:预紧力到24 kN时扣件安装到位,即使无其他荷载作用,弹条本身就已存在相当大的应力值,过拧将继续增大应力值;车轮多边形磨耗阶数的提高会增大弹条应力值,3阶磨耗时应力增量36 MPa,较无磨耗增大5倍,疲劳寿命较无磨耗状态降低95％;曲线半径减小和车速提高将增大弹条应力,降低其疲劳寿命,其中半径影响更显著,半径4000 m时弹条寿命2万次,较8000 m减少98％以上.本文可为扣件的养护维修提供参考.

为研究大范围的双块式无砟轨道离缝对高速行车安全性的影响及其伤损等级评定,基于列车脱轨能量随机分析理论,提出一种无砟轨道典型病害的动力影响评估方法.建立含离缝的高速列车-双块式无砟轨道系统损伤模型,分析不同程度的离缝和车速对此系统横向振动稳定性及其振动响应的影响.研究结果表明:离缝条件下的列车抗脱轨系数随着车速提高而逐渐下降,当车速350 km/h和脱空长度5 m时,抗脱轨系数1.908,列车安全运行有保障;离缝宽度和长度增加引起车轨系统振动响应增加;车速300 km/h及以下,离缝长度不超过5.0 m,宽度在1.0～2.0 mm时,伤损评定Ⅰ级,维修标准建议Ⅰ级;离缝宽度在2.0 mm以上,伤损评定Ⅱ级,维修标准建议Ⅱ级.上述机理和数据可为双块式无砟轨道离缝维修标准制定提供参考.

According to the structural damage characteristics of ballastless track of high-speed railway by investigation, a novel method for evaluating the influence of ballastless track of high-speed railway is presented. The dynamic model of ballastless track with damage property is established based on train-track spatial vibration system. The calculated and in situ tested results were compared to certify the model and computation program. Taking the track slab imperfections occurred in a tunnel along the real high-speed railway as an example, the influence of vibration responses of the train-track system with slab imperfections under different conditions is calculated and analyzed in comparison with normal slab. In addition, the maintenance effect on the repaired track structure is evaluated by considering the operate safety and comfort of high-speed train. It is concluded that large amplitude of slab arch imperfection results in higher acceleration of slab and car body. Therefore, train operation speed should be controlled in accordance with the safety standard such as wheel load reduction rate and derailment coefficient. In the case of low amplitude of slab arch imperfection, train operation speed should be controlled in accordance with the comfort standard such as Sperling index. The specific operation velocities were given correspondingly. Therefore, the mechanism and conclusions above can forecast intuitively in the field of track maintenance. The paper proposes a practical and valuable method for evaluating double-block ballastless track of highspeed railway.

In order to study the influence of slab-upwarp on the running stability of train and the performance of ballastless track structure, a damage model of double-block ballastless track and high-speed train system with slab-upwarp was established, and the calculation program of the model was compiled and verified by FORTRAN. Then, the spatial vibration response of four types of double-block ballastless track with slab-upwarp under high-speed train was calculated on the basis of the analysis theory of spatial vibration of high-speed train and ballastless track system, respectively. The influence law of different type of slab-upwarp, track irregularity amplitude and speed on the dynamic response of the system was analyzed and compared, and the damage ratings of the slab-upwarp was also analyzed. It is shown that the dynamic responses of the system with different type of slab-upwarp increase with the growth of running speed and track irregularity amplitude. The system response of slab-upwarp considering both complex track irregularity and void is the largest at the same speed, while that of slab-upwarp only considering vertical track irregularity is the lowest. For example, the maximum value of vehicle vertical acceleration, wheel-rail force, and derailment coefficient and wheel load reduction rate induced by the 1st type of slab-upwarp (A=11 mm, v=300 km/h) is 0.918 m/s2,100.740 kN, 0.305, 0.255, respectively; while those due to the 4th type of slab-upwarp are order of 2.037m/s2, 185.219 kN, 12.503, 1.727. The mechanism and data above should be provided a reference of damage rating for slab-upwarp.

To explore the influence of gap on deformation and deterioration stress of track structure, a finite element model of CRTS-I slab ballastless track with gap is established by ABAQUS on the basis of plastic damage constitutive relation of concrete. The effects of different sizes and different positions of gap on displacement and stress of the track structure are calculated and analysed. The influence law of gap on deformation and deterioration stress is drawn by comparison with the calculation of normal track structure. The results show that increasing gap size sharply increases vertical displacement of both rails and slab and also seriously deteriorates transversal and longitudinal stress on the track slab to a great extent. Moreover, the effect of gap at slab centre on deteriorated stress and deformation is less than that of gap at slab end. The study can obviously provide theoretical reference for the maintenance standard.

For the determination of the reasonable range of track stiffness to prevent the freight train derailment,the analysis method for the lateral vibration stability of freight train-track(FTT)system was proposed based on the train-track spatial vibration calculation model and the random energy anal-ysis method for the train derailment.The anti-derailment capacity,the lateral vibration stability and the corresponding vibration response in FTT system on the multiple combination of the fastener and ballast bed lateral stiffnesses were analyzed.Results show that the anti-derailment capacity,critical speed and allowable limit speeds of the FTT system are significantly increased with the increase of the fastener and ballast bed lateral stiffnesses;while the fastener and ballast bed lateral stiffnesses, respectively,increase to 90 MN/m and 10 MN/m,the increased amplitudes decrease.Meanwhile, when the fastener and ballast bed lateral stiffnesses,respectively,increase from 120 MN/m to 150 MN/m,and from 15 MN/m to 20 MN/m,the anti-derailment capacity,critical and allowable limit speeds of the FTT system are increased by only 3 .9% 1 .8% and 1 .8%,respectively.Moreover, increasing the lateral stiffnesses of the fastener and the ballast bed contributes to reducing the lateral displacement of the track structure.In conclusion,considering the rigorous market competition of heavy-haul railway,it is suggested that the fasteners lateral stiffness and the ballast bed lateral stiff-ness should be from 90 MN/m to 120 MN/m and from 10 MN/m to 15 MN/m,respectively.

Considering the general structure characteristics of bridges in heavy haul railway, the freight train-track-bridge(FTTB) system spatial vibration calculation model was established. Meanwhile, based on the random energy analysis theory of train derailment, the analysis method of lateral vibration stability of FTTB system was proposed. Through a calculation example, the lateral vibration stability and the corresponding vibration response of FTTB system before and after the reinforcement of the circular pier were calculated. The results show that the anti-derailment capacity of FTTB system increases by 50％ after the circular pier reinforcement in the calculation example. Before and after the circular pier reinforcement, the lateral vibration critical speed of FTTB system is 134.45 km/h and 156.99 km/h, and the admissible limit speed is 107.56 km/h and 125.59 km/h, respectively. After the reinforcement, the operation stability of freight train is guaranteed when the freight train passes over the bridge with speed of 80 km/h. Moreover, the lateral displacements of the bridge mid-span and the top of the pier are reduced by 54.5％ and 83.8％, respectively, comparedwith those before the reinforcement. In conclusion, this method reflects not only the freight train derailment information but also the spatial vibration characteristic of FTTB system. It can provide more comprehensive and scientific evaluation for the derailment precautions of the freight train.

The expression of sodium voltage-gated channel alpha subunit 2 (SCN2A) is closely related to the development of epilepsy. This study investigated regulatory element of the SCN2A gene involved in epilepsy. An intractable epilepsy cell model was constructed using hippocampal primary neurons and the SH-SY5Y cell line. SCN2A protein and gene expression in cells as well as the level of lactic acid dehydrogenase (LDH) in the cell culture supernatants was detected. Potential regulatory factors of SCN2A and its upstream regulatory elements were identified using the dual-luciferase reporter assay. Finally, the role of the hypothetical transcription factor in epilepsy was examined by using its small interfering RNA (siRNA). Results found that levels of LDH and expression of the hypothetical transcription factor, Forkhead box D3 (FOXD3), was both increased in the model cells, whereas that of SCN2A was decreased. The results of dual-luciferase reporter assays revealed that an upstream region of SCN2A gene spanning from nucleotides -1617 to -1470 was a transcription factor binding region and a trans-acting factor role of FOXD3 was identified in the core region (GGCAAAATTAT). Then the FOXD3 binding site was further verified by the chromatin immunoprecipitation (ChIP) assay and electrophoretic mobility shift assay (EMSA). After SH-SY5Y cells were transfected with FOXD3 siRNA, the release of LDH into culture supernatants and the LDH expression levels in cells were significantly decreased. SCN2A expression in model cells was increased by knockdown of FOXD3. Therefore, this study demonstrated that FOXD3 is a trans-acting factor of SCN2A, and this mechanism may play a role in cell injury after epilepsy.

On the basis of the freight train-ballasted and ballastless track system spatial vibration calculation model,using the random energy analysis method of train derailment,the whole train derailment course for the ballasted and ballastless track was calculated respectively.The lateral vibration ultimate resistance working on two train-track systems and the corresponding dynamic responses was obtained.Meanwhile,the freight train running safety and the spatial vibration characteristics for ballasted and ballastless train-track system were analyzed.The results show that compared with the ballasted track,the anti-derailment ability of ballastless track is improved by 45.9％,and the car body vertical Sperling stability index,the wheelset lateral force and the wheel-rail vertical force are reduced by 73.5％,22.1％ and 27.3％,respectively,when the train speed is 90 km/h.Moreover,the lateral displacement and acceleration of all the ballastless track components are much smaller than those of the ballasted track,while the rail vertical displacement of the ballastless track is larger.However,as the vertical displacement of ballastless track is taken by fastenings,the vertical displacement transferred from rail to roadbed slab is attenuated by 75.3％ on this account.The vertical acceleration of ballastless track is larger than that of ballasted track,the vibration and noise have more influence on the surrounding buildings.The ballastless track is recommended to be adopted in priority for the heavy-haul railway line design,but the vibration and noise reduction measurements should be taken on both sides of the track line.