Layered double hydroxides (LDHs) can shield polymeric materials from UV light, which allows reducing material aging and erosion damage of bituminous pavement under physical and chemical action. In this study, the physicochemical properties, aging resistance, and erosion resistance to the aqueous solution of LDHs modified bitumen mastic (BM) were characterized by Fourier-transform infrared spectroscopy, basic physical tests, viscosity tests, a dynamic shear rheometer, and a bending beam rheometer. The results show that few chemical reactions occurred between LDHs and BM, indicating that a physical mechanism underlay the modification of BM by LDHs. Moreover, LDHs could increase the flow activation energy of BM by 0.12%, increase the high failure temperature from 69.07 °C to 71.07 °C, and decrease the low failure temperature from −10.50 °C to −12.39 °C. Therefore, LDHs could slightly reduce the temperature sensitivity of BM, while slightly enhancing the high and low-temperature rheological properties of BM. Compared with short-term aging and long-term aging, LDHs could significantly improve the UV aging resistance of BM. The above results are consistent with previous studies of LDHs-modified bitumen. Furthermore, water and pH 3 acidic solutions had the greatest degree of erosion to BM, and LDHs could improve the resistance to aqueous solutions. Overall, this study can help to investigate the effects of various environmental factors on the performance of LDHs modified bitumen pavements during long-term use.

针对长大隧道内轨道养护维修困难、基础上拱变形、病害整治难度大的问题,在弹性长枕式无砟轨道的基础上优化,提出了隧道内长枕式无砟轨道,通过扣件和枕下垫板组成的双调高系统进行垂向调高;基于有限元法和车辆-轨道耦合动力学理论,对其进行受力状态和参数分析.结果 表明:隧道内长枕式无砟轨道可通过更换枕下垫板实现向下80 mm的调整量,列车通过时,安全性与平顺性能够满足要求;为保证轨道结构刚度合理,建议枕下垫板刚度取值在60～140 kN/mm之间.

针对我国西南地区地形变化多端、地质复杂多样等特点,分析总结西南地区铁路轨道工程建设面临的关键问题,包括短路基频繁过渡导致轨道结构无法成段铺设、线下基础易变形导致轨道变形超限、高烈度地震区分布广泛等.针对线下基础频繁多变和变形不易控制问题,设计了单元分块式无砟轨道技术方案;针对线下基础上拱影响运营安全且无法预测,研发了高承轨台无砟轨道及配套打磨技术和装备,并开展上线试验验证;针对特殊大跨度桥梁线形控制困难问题,研发了聚氨酯固化道床技术和轨道线形施工控制技术;针对高烈度地震区无砟轨道与线下基础之间的薄弱环节,提出无砟轨道加强技术方案.上述西南地区铁路轨道设计创新技术已在沪昆、云桂高铁等项目得到应用和验证,效果良好.

Fuel oil leaked onto asphalt pavement will damage the asphalt layer by dissolving the binder, softening the mixture and finally resulting in distress such as raveling and pitting. In the meantime, the skid resistance, high temperature stability and water stability deteriorate dramatically. Silicone resin is a fog sealing material for asphalt pavement. It forms a three-dimensional network structure with -Si-O- chains and therefore shows strong hydrophobicity and chemical stability. This paper looks into the effect of silicone resin on the fuel oil corrosion resistance of asphalt mixture. The contact angle, Cantabro test, water stability test, wheel tracking test and three-point bending test were used to investigate the road performance and the corrosion resistance under diesel and gasoline. It was found that, compared with diesel, the contact angle between gasoline and asphalt is smaller, indicating better compatibility. The gasoline corrosion decreases the properties of asphalt mixture more than that of diesel, which indicates that the compatibility is related to the corrosion effect. The results also show that silicone resin can effectively improve the adhesion, strength, water stability and high- and low-temperature performance of asphalt mixture before and after fuel oil erosion, and the improving effect on asphalt mixture after oil erosion is better.

During the service period, asphalt materials are affected by various natural factors, including heat, ultraviolet light, oxygen and moisture, etc., resulting in the reduction of pavement performance, the increase of pavement distress and shortening of service life. This study aims to investigate the aging performance of asphalt under multiple aging conditions of heat, UV and aqueous solution. Thermal-oxygen aging, UV aging and hydrostatic erosion tests were carried out sequentially on asphalt. The rheological properties, chemical structure and element composition of asphalt were characterized before and after aging, and the effect mechanism of multiple conditions was discussed. The results show that the multiple conditions of heat and UV can increase the rutting resistance and weaken the cracking resistance of asphalt. However, the effect degree of UV decreases gradually with the deepening of aging degree. Additionally, the effect of water on the physicochemical properties is less than that of UV; however, water can increase the sensitivity of physicochemical properties to UV. In summary, this study explored the short-term cycling effect of heat, light and water on asphalt and provided an idea for simulation test of asphalt under multiple aging condition.

为探索和加快研究落实铁路轨道工程数字化,在宁淮高铁轨道工程设计中进行了BIM技术应用,基于专用轨道BIM设计软件进行了快速建模和设计成果交付.基于创建的轨道模型,实现了轨道工程与线下基础之间的接口检查及优化、轨道工程数量自动统计、轨道工程二维图纸输出和无砟轨道关键施工数据提取等应用,在保证BIM设计效率的同时取得了满意效果,交付成果满足轨道设计和铁路行业BIM相关标准要求.铁路轨道工程BIM技术应用方法具有普遍适用性,可在高速铁路、城际铁路、客货共线铁路以及城市轨道交通等轨道设计中推广使用.

针对复杂艰险山区隧道内无砟轨道调整量小、基础变形病害整治难度大的问题,提出一种高度可调、主动适应基础变形的新型弹性长枕式无砟轨道.该轨道调高系统由"扣件+承轨台+枕下垫板"组成,可实现垂向-106～46 mm的调整量,适用于隧道基础变形过大地段.通过建立新型弹性长枕式无砟轨道力学模型,分析该轨道结构在不同调高状态下的受力与变形.结果表明:为满足轨道结构调高的要求,并兼具减振降噪,建议新型弹性长枕式无砟轨道的橡胶套靴弹性模量取9 MPa;该新型弹性长枕式无砟轨道在不同调高状态下钢轨位移及各部件受力均小于其限值.

本文针对既有CRTSⅢ型板式无砟轨道能否满足400 km/h及以上速度列车正常运行的问题,基于有限元方法建立了CRTSⅢ型板式无砟轨道的车辆-轨道耦合动力学模型,分析了列车以400～600 km/h速度正常通过桥梁与路基基础直线地段时车辆与轨道的动力特性,并参考《高速铁路工程动态验收技术规范》的规定限值,对各项动力性能指标进行评判.研究结果表明:(1)CRTSⅢ型板式无砟轨道结构与技术标准满足400 km/h+高速列车的正常运行条件,随着列车速度的增大,轮重减载率有较明显的增大;(2)列车舒适性与平稳性均处于较优状态,无砟轨道各动力性能指标均未超过最大允许值;(3)相较于桥梁基础,路基基础上的列车轮重减载率较小,轨道板垂向位移偏大,为确保400 km/h及以上速度列车的长期运营安全,路基基础刚度不宜过低.

研究目的:为有效解决隧道内无砟轨道上拱病害,基于双块式无砟轨道,提出一种大调整量新型高承轨台无砟轨道.通过ANSYS和LS-DYNA有限元软件建立精细化的静、动力学有限元模型,研究不同工况下新型高承轨台无砟轨道的受力特性,并与双块式无砟轨道对比分析.研究结论:(1)在列车静荷载和基础上拱变形作用下,新型高承轨台无砟轨道的受力变形和双块式无砟轨道无太大区别,轨道结构最大应力和位移均满足普通无砟轨道设计要求;(2)通过打磨轨枕块实现轨道结构垂向-50～0 mm的向下大调整量,满足结构最大应力和位移限值要求;(3)在列车动荷载作用下,新型高承轨台无砟轨道与双块式无砟轨道的各项动力响应指标均相差不大;新型无砟轨道打磨前后的轨道结构动力响应无明显区别,基础上拱后通过打磨轨枕块调整轨道结构,对高速列车行车的安全性和稳定性有显著提升;(4)针对隧道内无砟轨道上拱问题,本研究可为隧道内无砟轨道的设计和施工提供借鉴和参考.

为分析DTⅢ型扣件系统e型弹条在钢轨波磨条件下的疲劳损伤及其疲劳类型,首先建立包含e型弹条在内的扣件系统局部有限元模型,然后建立车辆-轨道耦合动力学模型,获取单个转向架通过时的钢轨垂向位移时程曲线,以此作为边界条件输入至有限元模型中,获取e型弹条的应变、应力时程变化规律,最后采用相应的疲劳理论对e型弹条疲劳损伤及其疲劳类型展开分析.研究结果表明:e型弹条在钢轨波磨条件下的疲劳损伤最大位置在弹条后拱与跟端相接处;曲线波磨条件下弹条疲劳损伤大于直线波磨,与实际运营情况相符;弹条疲劳寿命大于转变寿命,其疲劳类型为应力疲劳.

针对复杂艰险山区隧道线下基础变形病害整治难度大且现有轨道结构垂向调整量小的问题,提出了垂向调高系统由调高扣件+高承轨台结构+板下CA砂浆灌浆袋组成的高承轨台框架板式无砟轨道,基于有限元理论建立了相应的静动力学模型,明确了该型无砟轨道的静动力学性能.结果表明:为保证轨道结构的工作性能,建议板下袋装CA砂浆的弹性模量取200～300 MPa,板中空洞长度为2000 mm;当列车高速运行在高承轨台框架板式无砟轨道上时其安全性和平顺性均能得到满足.

线下基础上拱是隧道内无砟轨道线路常见病害之一,基础变形过大会破坏无砟轨道结构整体性,危害列车安全平稳运行.为快速适应隧道内轨下基础形变,结合弹性支承块式无砟轨道与框架板式无砟轨道优点,提出具有立体式调节系统的新型活动承轨台框架板式无砟轨道.基于有限元法分析不同结构参数对轨道结构力学的影响,验证大调整量下CA砂浆灌浆袋、承轨台高度的安全性能,根据计算结果,建议橡胶套靴下部刚度取450kN/mm,CA砂浆弹性模量取250～300MPa.通过动力学计算验证160、200、250 km/h速度下列车运行安全平稳性,表明列车横垂向振动加速度、轮轨横向力、轮重减载率、脱轨系数标均低于规范限值.研究成果对隧道内大调整量无砟轨道改良提供新参考方向.

本文基于车辆-轨道耦合动力学理论,建立了考虑柔性车体的高速列车-轨道耦合动力学模型,对比分析了轨道几何不平顺波长变化对典型高速动车组动力学性能的影响规律,探讨了400 km/h行车速度条件下高速铁路轨道几何不平顺的敏感波长.结果表明:(1)400 km/h高速铁路轨道几何不平顺敏感波长主要存在两个范围,短波范围的敏感波长主要与动车组车体的柔性模态有关,中长波范围的敏感波长主要与动车组车辆系统的刚体模态有关;(2)由于悬挂参数的差异,不同型号高速动车组对应的轨道几何不平顺敏感波长存在明显差异,在制定线路养护维修标准时,应考虑整条线路上所有运营的动车组型号;(3)不同类型轨道几何不平顺的敏感波长也存在差异,应针对不同的轨道几何不平顺类型制定相应的敏感波长管理标准.

针对复杂艰险山区铁路隧道内区段较为严重且整治难度较大的基础变形病害,提出了一种隧道内新型组合轨枕块式无砟轨道,能充分适应轨道下部基础的变形,并基于有限元法对该结构的不同参数进行了力学分析.结果 表明:为保证钢轨垂横向位移及轨道结构各部分所受拉应力值较小,建议组合式轨枕块的长宽高分别为830,276,140 mm;凹槽的深度宽度分别为80,970 mm;凸出高度为60 mm;为保证结构的整体性,建议组合式轨枕块选取聚氨酯材料;列车在新型组合轨枕式无砟轨道上运行时,其安全性与平顺性均满足要求.

为解决复合轨枕道床横向阻力不足的问题,基于复合轨枕材料和结构,提出横向阻力增强方案.采用3D扫描技术生成道砟颗粒模板库,构建轨枕-道床离散元三维模型,模拟分析了各种纹理复合轨枕对道床横向阻力的分担规律及其增强效果,并从细观层面分析了轨枕与道砟颗粒相互作用机理.结果 表明:与普通条形复合轨枕相比,A1型,A2型,A3型,A4型,A5型纹理复合轨枕道床横向阻力可分别提高9.3％～11.4％,17.8％～23.6％,27.4％～32.0％,16.6％～21.8％,17.7％～21.2％;在复合轨枕与道砟接触表面设置纹理可增强轨枕表面与道砟颗粒之间的咬合,有效增大轨枕底面与道砟颗粒接触数目及轨枕侧面与道砟颗粒间平均接触力,提高枕底及枕侧阻力.

The combination of immune checkpoint inhibitors (ICI) and thoracic radiotherapy (TRT) has shown significant clinical activity for non-small cell lung cancer (NSCLC) patients in preclinical and clinical study. However, the available adverse effect (AEs) data of combination treatment were based on a small subset of data from prospective clinical trials or retrospective studies. Thus, we conducted this systematic review to determine the complete toxicity profile of combination treatment. An electronic literature search was performed in database and conference proceedings for prospective clinical trials of combining ICI and TRT for NSCLC patients. The systemic analysis was conducted to determine the toxicity profile of ICI and TRT in NSCLC patients. The difference of AEs between PD-1 and PD-L1 inhibitors and the toxicity profile of sequential and concurrent ICI and TRT was further analyzed using the Review Manager and Stata version 12.0. 9 clinical trials enrolled 815 NSCLC patients were eligible for analysis. The incidence of all-grade AEs was 88.7%, high-grade AEs (grade≥3) was 21.2%. The most frequent all-grade AE was fatigue (30.4%), and pneumonitis occurred with the incidence of 21%. Pneumonitis was the most common high-grade AE and grade 5 AE with the incidence of 3.4% and 0.9% respectively. Notably, the toxicity profile and the incidence of high-grade pneumonitis was similar between PD-1 and PD-L1 inhibitors (22.2% vs 29.8%, P = 0.38; 4.6% vs 3.3%, P = 0.44), and concurrent and sequential ICI and RT (23.9% vs 21.5%, P = 0.81; 6.1% vs 3.1%, P = 0.21). Most AEs of combination treatment are tolerable, and pneumonitis deserves utmost attention as the most common high-grade AE. The toxicity profiles were similar in patients receiving PD-1 or PD-L1 with TRT, and were also similar in patients receiving concurrent or sequential treatment. This comprehensive analysis could lay a foundation to accelerate the development of combining ICI and TRT treatment, to achieve the goal of maximizing the benefits and minimizing toxicities.

Asphalt pavement will be damaged under the action of asphalt aging and moisture damage. Water solution erosion degree is closely related to the aging of asphalt and degradation of the adhesive strength between asphalt and aggregate. In view of this, this paper investigated the effect of water solution erosion on rheological, cohesion and adhesion properties of virgin and aged asphalt. The experiment was performed by immersing asphalt into five different water solutions (includes distilled water, acid solution, alkali solution, sodium chloride solution and sodium sulfate solution) for different time, which was considered to be fully reflect the real service condition within an asphalt pavement in different areas. The rheological properties were evaluated by dynamic shear rheometer (DSR), the cohesion and adhesion properties based on the surface free energy test were got by sessile drop method. Meanwhile, the relationships between asphalt rheological, cohesion and adhesion properties with aqueous solute and water solution erosion time were studied. The effects of water solution erosion on virgin asphalt and its PAV aged asphalt were compared. It was observed that water solution erosion resulted in the increased of asphalt elastic component and stiffness, decreased of asphalt fatigue life and the cohesive force and adhesion to aggregates. This trend was reduced to some extent with the presence of acid, alkali, and salt solutes. Under the action of water solution erosion, PAV aged asphalt showed a worse resistance to water solution erosion. And unlike heat-aging and ultraviolet-aging, the development trends of rheological, cohesion and adhesion properties of asphalt were more complex and variable with the change of asphalt surface component. (C) 2020 Elsevier Ltd. All rights reserved.

针对莫斯科至喀山高铁所具有的高速、宽轨距、严寒、高温差且采用客货混运的特点,论述了该项目轨道系统的设计理念,介绍了无砟轨道系统选型、轨道与车辆系统耦合动力学分析、高速道岔系统的研制及CRTSⅢ型板式无砟轨道板最优化配置等创新设计成果.

研究目的:钢枕具有100％可再生、可循环利用的优势,适用于不同速度、轴重、轨距的线路;设计和应用灵活,能够降低桥隧建筑结构高度;钢枕安装和运输方便,在“一带一路”国家中均有大量应用.由于钢枕结构和材质原因,其道床阻力较低,限制了钢枕应用范围的扩大.本文通过采用加肋和设置橡胶垫方式来提高钢枕道床横向阻力,进行不同条件下道床横向阻力试验研究.研究结论:(1)普通钢枕道床横向阻力为Ⅲc型混凝土轨枕的51.9％ ～ 62.4％,远低于普通铁路无缝线路设计要求,需要进行加强;(2)钢枕枕底、肩部及枕心道床横向阻力分担依次为52.8％ ～74.7％、11.3％ ～37.4％、9.9％ ～ 14.0％;(3)肋板可显著提升钢枕道床横向阻力,其作用优于砟肩堆高和加宽,且横向阻力随肋板数目增加而提高;(4)橡胶垫复合钢枕道床横向阻力均高于普通钢枕,大凸型增加比例为3.0％ ～5.9％,小凸型增加比例为22.2％ ～25.5％;(5)本研究成果可为扩大钢枕应用范围提供参考.

在有砟轨道结构中,轨枕是其重要的组成部件.如今出现了以玻璃纤维、聚氨酯、废旧塑料、树脂等复合材料为原料制成的新型轨枕.复合轨枕与传统轨枕相比,具有质量轻、设计灵活、安装方便、耐腐蚀性好、环境友好等优势,有巨大发展潜力和市场.然而,由于设计、生产工艺、成本等因素限制,复合轨枕面临许多问题而未被广泛应用.对复合轨枕目前面临的主要问题,如性能指标不足、横向阻力低、价格高昂等进行梳理和总结,并从材料、结构、设计标准等方面探讨解决方法,进一步促进复合轨枕安全性和可靠性提升,促进我国铁路绿色发展.