青藏铁路多年冻土区水害类型及防治措施

研究目的：针对青藏铁路多年冻土区的主要水害类型，结合青藏铁路（二期）工程设计实例和施工现场情况，提出了病害处理原则和防治措施。 研究方法：首先从理论上对冻土及多年冻土进行了阐述，然后联系青藏铁路（二期）工程，从路基工程、涵洞工程、桥梁工程3个方面出现的各种水害类型分析入手，得出结果。 研究结果：路基工程、涵洞工程、桥梁工程3个方面出现的各种水害类型各有不同，但对青藏铁路今后的运营都将产生不同程度的影响，因此必须采取相应的防治措施。 研究结论：多年冻土地区铁路工程设计施工的原则应针对多年冻土各种不同的地质特征，进行科学的分析，做出具体的处理措施，保证青藏铁路建设工程的经济合理性、安全性和可靠性。运营期对路基、涵洞、隧道和桥梁等铁路工程建筑物采取合理防护，从而确保青藏铁路建设工程的质量及正常运营，从根本上抑制变形、裂缝等水害的发生和发展。     

地质雷达在公路隧道超前地质预报中的应用

介绍地质雷达的工作原理和使用方法,论述利用地质雷达对隧道掌子面进行超前地质预报时参数的选取及注意事项,并结合实际工程总结出围岩不良地质体在地质雷达图像中的显现特征,得出相关结论。     

钻孔穿越岩溶裂隙带地层漏浆处理方案探讨

针对霍永高速公路汾河特大桥桩基施工过程中出现的漏浆现象,通过采用水泥、红泥球和片石3种堵漏方法进行试验,提出了3种不同堵漏方法及相应的适用范围,并取得了良好的施工效果,可为类似桩基堵漏施工提供借鉴。     

Real-time merging traffic control for throughput maximization at motorway work zones

Work zones on motorways necessitate the drop of one or more lanes which may lead to significant reduction of traffic flow capacity and efficiency, traffic flow disruptions, congestion creation, and increased accident risk. Real-time traffic control by use of green–red traffic signals at the motorway mainstream is proposed in order to achieve safer merging of vehicles entering the work zone and, at the same time, maximize throughput and reduce travel delays. A significant issue that had been neglected in previous research is the investigation of the impact of distance between the merge area and the traffic lights so as to achieve, in combination with the employed real-time traffic control strategy, the most efficient merging of vehicles. The control strategy applied for real-time signal operation is based on an ALINEA-like proportional–integral (PI-type) feedback regulator. In order to achieve maximum performance of the control strategy, some calibration of the regulator’s parameters may be necessary. The calibration is first conducted manually, via a typical trial-and-error procedure. In an additional investigation, the recently proposed learning/adaptive fine-tuning (AFT) algorithm is employed in order to automatically fine-tune the regulator parameters. Experiments conducted with a microscopic simulator for a hypothetical work zone infrastructure, demonstrate the potential high benefits of the control scheme.     

Effectiveness of graphic-aided portable changeable message signs in reducing vehicle speeds in highway work zones

Portable changeable message signs (PCMSs) have been employed in highway work zones as a temporary traffic control device for decades in the United States. Results of previous research showed that the traditional text-based PCMS had several limitations, such as having a short range of legibility and being difficult to read by elderly and non-English-speaking drivers. A few simulation studies indicated that using graphic-aided PCMSs could likely overcome these limitations. This paper presents the results of field experiments that were conducted to determine the effectiveness of graphic-aided PCMS in reducing vehicle speeds in the upstream of highway work zones. In field experiment Phase I, a full-matrix PCMS was programmed to display a work zone graphic and a flagger graphic, which were similar to the W21-1 sign and W20-7 sign, respectively, specified by the Manual on Uniform Traffic Control Devices. In field experiment Phase II, the PCMS was programmed to display two alternative work zone graphics along with the original work zone graphic. 1115 and 1600 valid vehicle speed data were collected during field experiments Phase I and Phase II, respectively. The results of data analysis suggested that graphic-aided PCMSs reduced mean vehicle speeds between 13% and 17% in the upstream of a work zone. This study provided valuable knowledge to government agencies and the transportation industry on how to regulate and implement graphic-aided PCMS in highway work zones.     

“潮汐式”可变航道方案研究与可行性分析

为提高航道整体通航效率,借鉴道路交通中的先进经验,提出“潮汐式”可变航道的概念.建立一种新型的双向航道分道通航模式,在高峰时段为重交通方向向左扩展航道,同时满足两侧通航需求.提出可变航道实施的方案,分析了可变航道实施的关键技术,即动态时间和动态空间的确定,并指出了这两个参数的进一步研究方向.以长江口深水航道为例,通过两种不同的设计船型对可变航道实施的可行性进行了验证.结果表明,可变航道具有广阔的研究和应用前景.初步研究了可变航道的实施和管理方案,为可变航道未来的实施发展奠定了基础.     

A Local Transboundary Approach to the Governance of Mediterranean Coastal Borderlands

Abstract

Coastal borderlands are subjected to particular socioeconomic, political and environmental dynamics in Europe and worldwide. The presence of the international boundary in these areas poses challenges in the process of Integrated Coastal Zone Management (ICZM). The aim of this paper is to explore the existence, characteristics and the role that local cross-border cooperation plays in transboundary coastal zone management as well as the resulting potentialities of local endogenous development for improving the management and governance of the tourism sector, coastal development, fisheries and marine protected areas in the Albera Marítima (Northwestern Mediterranean). The applied methods included document review, statistical information and semi-structured interviews. The research shows that local agents are not capable of developing a stable cross-border network due to persisting lack of trust, weak joint strategic vision and high competitiveness in sectors like fishery and tourism. Based on particularly interesting initiatives occurred in Albera Marítima and other successful experiences in Mediterranean coastal borderlands, a proposal has been made to implement several measures, including a transboundary integrated coastal plan, the joint observatory of fishery resources and a scientific network platform. For the aforementioned issues, the study contributes to the ICZM literature by providing a new perspective on local transboundary cooperation.     

Altruism,selfishness and coastal resources

Abstract

The basis for coastal zone management in the United States is established in legislation. In comparison, Canadian federal and provincial governments have adopted a piecemeal approach for managing a variety of concerns examined here: water quality, ecological protection, public access, aesthetics, natural hazards, and water dependency. As a result of this approach, which is characterized by a minimum of federal, provincial, and interjurisdictional coordination, the British Columbia coastal zone is showing signs of stress. For example, major shellfish harvesting areas are being lost to water pollution; ecologically sensitive habitats are being consumed by urban, commercial, and industrial expansion; recreation and tourism opportunities are being impaired by clear cutting and other inappropriate developments; and infrastructure is allowed in flood and erosion‐prone areas. Recommendations to improve the approach to coastal management in British Columbia include a variety of innovations. New federal and provincial policies, legislation, institutions, and experimentation with local and regional integrated resource planning are required to better govern the coastal zone. Increased support for existing agencies, public involvement, and access to information as well as more common use of environmental impact studies are needed to justify proposed coastal developments.     

长江口北槽深水航道整治工程贮泥坑抛泥过程监测分析*

对北槽航道维护使用的3#贮泥坑抛泥流失率进行现场监测和分析研究。监测内容包括应用多波束地形测量仪测 得贮泥坑抛吹泥前后的准确容积变化,采用表层取样法测量贮泥坑抛泥后的表层泥沙密度及采用柱状采样器测量贮泥坑不 同深度的泥沙密度,综合容积变化和密度结果可以得到实际入坑泥沙量,结合实际抛泥量计算出贮泥坑的抛泥流失率。监 测结果表明该贮泥坑的抛泥流失率达到76%。同步监测的流速结果表明贮泥坑周边动力强、流速快,流速快是造成该贮泥 坑抛泥流失率大的主要原因。建议该坑向附近动力弱的坝田掩护区移动以减少该贮泥坑泥沙流失率。     

Collision avoidance analysis for transition taper length

Transition taper length plays a vitally important role in work zone safety operations because too short a transition taper length will result in higher accident risks and too long a transition taper length could increase traffic delay. This paper evaluates transition taper length under various traffic conditions and road geometries using collision avoidance analysis. The longitudinal distances for lane changing and emergency stopping manoeuvres are respectively calculated using collision avoidance analysis. The higher value between the longitudinal lane changing distance and emergency stopping distance is considered as the expected transition taper length. The comparison of transition taper lengths from the collision avoidance analysis and current empirical transition taper formulae shows that the collision avoidance analysis has the capability of evaluating transition taper lengths. This paper also contributes to providing theoretical supports for these empirical formulae.