Development and application of an integrated traffic simulation and multi-driving simulators

Professional virtual reality experiment tools, including driving simulators and traffic simulators, have their strengths and weaknesses. The integration of the two simulators will enhance the ability of both traffic modeling and driving simulation and present a new area of applications. This paper develops, implements, and validates an experimental platform that integrated a traffic simulator with multiple driving simulators (TSMDS). As a connected multi-user framework that allows multiple drivers who are simultaneously handling many driving simulators, it not only allows driver behavior experiments to be more accurate, controlled, and versatile but also simulates special driving behavior or multi-vehicle interactions under more realistic traffic flow environments. To validate the performance of TSMDS, 27 drivers were recruited to attend the lane changing experiments at a recurring on-ramp bottleneck and left-turn experiments at a two-phase signalized intersection in Shanghai. Both experiments required several drivers to drive the TSMDS and fulfill several complicated lane changing/crossing behaviors through their interaction. The results show that both the participants’ response and lane changing/crossing data that were obtained from the experiment are consistent with the field observation, which confirms the validity of the integrated platform.     

覆土不锈钢波纹板涵管的土—结构相互作用研究

覆土不锈钢波纹板涵(管)结构属于柔性结构,回填土与不锈钢波纹板结构之间具有很好的协同工作性。本文通过将土-结构相互作用分解为法向和切向行为,建立了覆土不锈钢波纹板涵的有限元模型,并考虑了不同摩擦系数的影响。研究结果表明,回填土与不锈钢波纹板之间的摩擦系数对不锈钢波纹板受到的法向和切向土压力均有影响;随着回填土厚度的增加,不锈钢波纹板涵受到的法向土压力将会逐渐趋于均匀分布。     

岛礁地形抛石护岸稳定性试验研究

岛礁地形是一种特殊的海岸形式,国内外学者对波浪在岛礁地形上的传播变形研究较多,但对于岛礁地形上的护岸工程研究较少,缺乏对关键设计参数的研究。以马尔代夫机场岛护岸工程为例,通过比例尺为1:10的波浪水槽物理模型试验,分析研究了3种不同岸坡宽度、4种不同水深和波浪组合工况下的护面块石稳定性。结果表明,前沿岸坡宽度,即护岸坡脚至礁缘之间的距离是影响抛石护岸稳定性的重要因素。在同样水深、波况及护岸块石质量条件下,护面块石的失稳率随岸坡宽度的增加而减小。进一步分析发现,为保障护岸安全,抛石护岸外坡坡脚宜布置于波浪破碎点之后,且与破碎点之间距离不应小于浅水波长的26%,即0.26T$ \sqrt{g h_{\mathrm{e}}}$。     

朱圩子立交桥面铺装病害分析及养护技术研究

对朱圩予互通立交原桥面铺装病害类型及成因进行调查分析,提出了相应的养护方案并从施工难易程度、可操作性等各方面进行对比分析,确定可行方案及相关技术要求,同时分析了沥青混合料添加抗车辙剂前后的压实特性,通过汉堡轮辙试验对其高温稳定性及水稳定性能进行对比验证。     

新型40 m级测量船动力系统设计优化

针对40 m级测量船功能需求的提高,对新建40 m级测量船的动力系统进行优化,采用技术成熟的滑差齿轮箱驱动螺旋桨的推进方式取代可调螺距螺旋桨推进方式,使新建船在作业航区、测量作业能力等方面有较明显的提升,且船舶的灵活性和安全性得到进一步提高,满足了近海测量作业的实际需求。     

添加剂对微表处混合料抗车辙性能改善效果的研究

近年来，微表处在广泛用于整幅罩面的同时越来越多地用于车辙修复。微表处车辙修复的主要破坏机制是高温稳定性不足。以改善乳化沥青残留物和微表处混合料高温稳定性为目标，通过乳化沥青蒸发残留物软化点和60℃布氏粘度试验、微表处混合料RLWT车辙试验等，对不同添加剂的改性效果和改性效果变化规律进行了评价，为车辙填充微表处混合料添加剂的选择提供参考依据。     

Study on mechanism of thermal spalling in concrete exposed to elevated temperatures

This paper presents a review of explosive spalling of concrete at elevated temperatures. The affecting factors, mechanisms and current theoretical and experimental studies are summarized. Using a numerical model proposed by the authors, numerical simulations were performed to investigate the effects of the thermally cracking process considering the effects of heterogeneity of the material properties on the spalling in concrete exposed to a transient thermal load. The investigations showed that the thermal cracking is the key factor causing the corner and surface spalling, and suggested that a coupling of thermal cracking and pore pressure is the main cause of explosive spalling and uncertainty of explosive spalling. The explosive spalling induced by elevated temperatures is a complex nonlinear problem, which can be understood only through establishing a methodology using behavioral aspects for both material science and mechanics.     

浇筑密实度和均匀度对结构混凝土耐久性的影响

为建立浇筑期结构混凝土耐久性质量控制方法,采用振动分层法,研究了混凝土浇筑密实度、浇筑均匀度对其渗透性的影响,建立了混凝土浇筑密实度和浇筑均匀度的量化控制方法——电阻率稳定区间法.结果表明:混凝土浇筑密实度和浇筑均匀度均决定于材料流动性和振捣时间;相比混凝土抗压强度,混凝土渗透性对浇筑密实度和浇筑均匀度更为敏感.通过计算量化判定电阻率稳定区间(SRER),并以其起点为判别点,可以保证混凝土浇筑密实度和浇筑均匀度处于综合最优状态,优化混凝土孔隙结构,显著提升混凝土抗渗透性能.     

煤层瓦斯压力及压力梯度影响因素的分析

由于煤层瓦斯压力的影响因素多且复杂,通过建立理论模型,得出了煤层瓦斯压力与煤层埋深、煤岩弹性模量、泊松比、温度梯度和地应力梯度等影响因素的关系式,并结合数值分析,对煤层瓦斯压力与其相关影响因素的关系进行了分析。通过分析得出,煤层瓦斯压力随着煤层埋深的增加而变大,在同一煤层埋藏深度,煤层瓦斯压力随弹性模量、泊松比、温度梯度的增加而降低,随地应力梯度的增加而增大。同时,煤层瓦斯压力梯度随煤岩弹性模量和泊松比的增大而增大,当煤岩弹性模量和泊松比较小时,煤层瓦斯压力梯度的变化率较小,当煤岩弹性模量和泊松比较大时,煤层瓦斯压力梯度的变化速率迅速增加。煤层瓦斯压力梯度随温度梯度和地应力梯度的增大而增大,基本呈线性变化。     

基于抗车辙性能的微表处混合料设计方法探讨

现行的微表处混合料设计方法主要针对薄层罩面工况,由WTAT实验得到的容许最小乳化沥青用量偏大,对抗车辙性能考虑不周。采用RLWT实验方法,研究发现微表处混合料在乳化沥青用量较低时其抗车辙性能对乳化沥青用量的变化不敏感,而当乳化沥青用量不断增大超过某一界限值UCEC（Upper Critical Emulsion Content）后,混合料抗车辙性能迅速下降。据此提出以（UCEC-0．2）作为容许最大乳化沥青用量,以油膜厚度不变原则对Ⅵ能T实验结果换算得到容许最小乳化沥青用量的微表处车辙填充混合料设计方法。