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针对高速铁路路基绿化工程高要求、少维护等特点,提出纤维团粒喷播技术,并详细阐述了其机理及特点.通过在京雄城际铁路路基边坡工程中的应用,归纳总结了该技术施工工艺流程:平整坡面→坡面覆土→铺设铁丝网→喷播基质→养护管理.喷播基质是利用喷播机械将性能优越的基质材料喷附至铁路路基坡面上的.工程应用表明该技术施工快,质量好,养护维修量小,经济性高. 相似文献
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With trajectory data, a complete microscopic and macroscopic picture of traffic flow operations can be obtained. However, trajectory data are difficult to observe over large spatiotemporal regions—particularly in urban contexts—due to practical, technical and financial constraints. The next best thing is to estimate plausible trajectories from whatever data are available. This paper presents a generic data assimilation framework to reconstruct such plausible trajectories on signalized urban arterials using microscopic traffic flow models and data from loops (individual vehicle passages and thus vehicle counts); traffic control data; and (sparse) travel time measurements from whatever source available. The key problem we address is that loops suffer from miss- and over-counts, which result in unbounded errors in vehicle accumulations, rendering trajectory reconstruction highly problematic. Our framework solves this problem in two ways. First, we correct the systematic error in vehicle accumulation by fusing the counts with sparsely available travel times. Second, the proposed framework uses particle filtering and an innovative hierarchical resampling scheme, which effectively integrates over the remaining error distribution, resulting in plausible trajectories. The proposed data assimilation framework is tested and validated using simulated data. Experiments and an extensive sensitivity analysis show that the proposed method is robust to errors both in the model and in the measurements, and provides good estimations for vehicle accumulation and vehicle trajectories with moderate sensor quality. The framework does not impose restrictions on the type of microscopic models used and can be naturally extended to include and estimate additional trajectory attributes such as destination and path, given data are available for assimilation. 相似文献
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根据隧道边仰坡三维坐标测量数据,通过计算边仰坡斜面和投影水平面的法向量,进而计算两面之间夹角的方法,反算边仰坡斜面面积,在类似不规则隧道边仰坡等斜面面积计算中具有广泛的应用价值。 相似文献
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The management of vehicle travel times has been shown to be fundamental to traffic network analysis. To collect travel time measurement, some methods focus solely on isolated links or highway segments, and where two measurement points, at the beginning and at the end of a section, are deemed sufficient to evaluate users' travel time. However, in many cases, transport studies involve networks in which the problem is more complex. This article takes advantage of the plate scanning technique to propose an algorithm that minimizes the required number of registering devices and their location in order to identify vehicles candidates to compute the travel times of a given set of routes (or subroutes). The merits of the proposed method are explained using simple examples and are illustrated by its application to the real network of Ciudad Real. 相似文献
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Optimal sensor placement on freeway corridor is of great interest to transportation authorities. However, current traffic sensors are easily subject to various failures. Therefore, it is necessary to incorporate sensor failure into the optimal sensor placement model. In this article, a two-stage stochastic model is proposed for the purpose of travel time estimation on freeway corridor. To balance the effectiveness and reliability, a stochastic conditional value at risk (CVaR) model is also proposed. Since both models are too complicated, a customized genetic algorithm is developed. Numerical experiments show that considering sensor failure makes a significant performance improvement in the sensor placement pattern. Sensitivity analysis is also applied to investigate the impact of a number of allowable sensors and different traffic sensor failure probability. 相似文献
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中国TBM施工技术进展、挑战及对策 总被引:1,自引:0,他引:1
总结我国近30年来TBM设计与施工技术的发展历程,可归纳为以下5个阶段:1)研发探索和试用阶段;2)以国外施工承包商为主体,采用国外设计制造TBM施工我国隧道工程阶段;3)独立进行TBM招标采购和选型设计,并建立起自主的TBM施工队伍阶段;4)与国外厂家联合设计制造TBM,工程应用和自主施工快速发展阶段;5)实现TBM国产化,面向国内外TBM工程市场自主施工阶段。通过我国不同时期TBM施工的典型工程,介绍我国在复杂地质、大坡度、高海拔、不同直径、不同机型、超长隧洞TBM施工方面取得的经验、技术积累和业绩,展示我国TBM在穿越断层破碎带、软弱变形、岩爆、涌水等不良地质洞段取得的一系列施工新技术,以及最高月进尺1 868 m、平均月进尺超过600 m和掘进作业利用率超过40%的掘进技术水平。分析TBM在极硬岩、大断层破碎带、软弱大变形围岩、强岩爆围岩、涌水突泥洞段、高地热隧洞和超长隧洞工程中施工面临的风险和挑战,并提出一些相应的技术措施和对策,期望这些措施和对策在未来大量实际工程中进一步得到实践验证、优化和改进,不断积累和创新TBM设计与施工新技术。 相似文献
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广东省山区高速公路发展迅速,但诸多挖方边坡在修建过程中就产生了不同程度的病害。这些病害产生的原因包括气候、地质条件和人为因素,给施工工期、造价及安全管理造成较大影响。鉴于塌方病害在广东地区山区高速公路挖方边坡中较为常见,根据破坏方式及影响范围的深度将其划分为浅层溜塌、浅层滑塌和深层滑塌(滑坡)。结合工程建设经验,提出了山区路堑边坡的防治策略,可为类似工程的设计、施工提供借鉴。 相似文献