小净距大跨度公路隧道安全风险管理与施工技术

小净距大跨度隧道风险影响因素复杂、施工期风险较大,需要开展有效的安全风险管理.通过对各类小净距大跨度隧道施工安全事故的分析统计,并结合现场施工实践,建立了安全风险评价指标体系,提出了施工阶段风险管理理念.文章引入ANP方法综合分析风险指标体系各指标间的相互关系,计算出各指标的整体权重,评价出施工中的主要风险源,并针对其制定了有效的施工控制措施.广安翠屏山隧道工程实践证明,实行安全风险管理可提高施工期安全水平,保证工程的顺利推进以至完工.其理论和方法可为同类工程所借鉴.     

山岭隧道洞身段震害规律与地震风险模糊综合评价分析

隧道洞身段长度因占隧道整个长度的比重较大,发生地震损坏的风险不容忽视。文章通过建立地震风险模糊综合评价模型,对山岭隧道洞身段地震风险进行了分析;收集整理了汶川地震中四川省境内59座山岭隧道震害资料,归纳出了影响隧道洞身段地震反应的10个主要因素,即埋深、施工情况、支护结构及强度、断面大小及形状、地震烈度、地震波传播方向、震中距、隧道长度、断层与软弱破碎带、围岩质量,并总结了与震害的关系;采用层次分析法计算地震风险因素的权重,选取梯形和语意隶属函数,应用模糊数学和加权平均法进行了模糊综合运算。通过将模糊综合评价模型应用于龙洞子隧道的工程实践,得出了洞身段地震风险级别为极高的结论;通过汶川地震中的实际震害也验证了该模型的正确性。     

岩溶地区隧道涌水风险的可拓评价模型及应用

岩溶地区隧道发生涌水灾害的风险大。文章基于可拓理论建立了岩溶区隧道涌水风险的可拓评估模型。在该模型中,首先建立岩溶区隧道涌水风险的多指标评估体系,并对评价指标做无量纲化处理;然后基于岩溶隧道涌水的评价指标的量测值建立待评物元;采用综合赋权法为各评价指标分配权重,其中指标的客观权重采用基于量测值的关联函数法确定,而主观权重采用基于专家知识的模糊层次分析法确定;最后推求待评隧道的物元关于涌水风险等级的关联函数值,通过最大关联度原则确定该隧道的涌水风险等级。同时,通过计算涌水风险等级的变量特征值来判断该风险等级偏向相邻等级的趋势。采用文章建立的风险可拓评价模型对某岩溶区隧道某里程段进行涌水风险评估,其评价结果与实际观测结果具有较好的吻合性,验证了该可拓评价模型的可靠性。     

公路隧道衬砌病害等级的模糊综合评价方法

文章结合工程实例,将AHP-Fuzzy算法应用于公路隧道的模糊综合评价,对模糊综合评价过程中指标集的建立、权重及隶属函数的确定方法、模糊算子的选取作了详细的阐述,建立了多层次模糊综合评价模型.并利用该评价模型对六甲洞隧道进行了健康状态综合评价,为公路隧道的模糊综合评价提供参考.     

浅埋暗挖大跨度隧道机电系统安全性模糊评价

文章以某浅埋暗挖大跨度隧道为例,基于隧道机电设备本身状况、运营管理体制、运营环境三方面考虑,利用AHP层次分析法与模糊数学理论,构建隧道机电系统的安全评价指标体系,并通过建立模糊评价矩阵,进行影响因素权重的计算,得到各个评价指标的权重分配,证明了该评价体系的有效性,为类似工程的安全性评价提供参考与借鉴。     

高速公路隧道系统交通安全评价模型研究

依据国内外现有的研究成果及现行的隧道设计规范,分析研究高速公路隧道交通安全影响因素;选取合理的评价指标,结合专家意见,运用层次分析法计算确定各指标权重,建立评价指标体系;依托某高速公路石古嶂隧道工程实例,对评价方法进行应用及验证。     

地铁联络通道冻结法施工安全风险评价

为评价地铁联络通道冻结法施工安全风险,文章依据相关文献并结合已有工程经验和类似工程记录,识别出联络通道冻结法施工四个阶段的主要风险要素,建立了评价指标体系,提出了一种基于层次分析法(AHP)、模糊综合评价法(FCE)和贝叶斯网络法(BN)的联络通道冻结法施工安全评价方法。首先采用层次分析法计算各风险事件的相对权重,采用风险经济损失值描述风险事件的影响后果,采用贝叶斯网络计算风险事件的概率等级分数;然后结合风险经济损失值和概率等级分数,并采用梯形隶属函数来计算风险事件对风险水平的隶属度,将风险事件的权重与风险事件对风险水平的隶属度进行模糊综合运算,可得出联络通道冻结法施工的总体风险水平;最后以兰州轨道交通1号线为例进行实例研究,得到该工程总体风险等级为低风险,评价结果基本能反应实际情况。     

公路隧道穿越断层塌方预测多级模糊综合评判

针对隧道穿越断层破碎带施工中塌方事故的预测,文章较系统地总结了隧道穿越断层中塌方事故的影响因素,并确定了主要影响因素;然后根据因素的层次性、模糊性,引入多级模糊评判方法、层次分析方法(AHP)等理论,建立了断层塌方预测的二级模糊综合评判模型和方法,以及指标权重及隶属函数的确定方法;通过工程实例对评判模型进行了验证分析,结果与实际情况较为吻合,说明隧道穿越断层破碎带塌方预测的多级模糊综合评判指标体系是有效的.     

基于熵权-云模型的隧道围岩分级方法研究

针对隧道围岩分级中的模糊性和随机性,文章将隧道围岩分级体系作为一个模糊系统,选取6个参数作为评价指标,基于熵权法和云模型提出了隧道围岩分级方法。利用正态正向云发生器生成了各评价指标隶属各围岩等级的云模型,并结合熵权法计算出客观权重值,得到了待评样本的综合确定度,从而确定隧道围岩等级。熵权-云模型将评价指标与围岩等级间的模糊性和随机性有机结合,实现了评价指标由定性描述到定量数值的转化,克服了传统隧道围岩分级方法固定评价模式的缺陷。最后,利用熵权-云模型对祥和隧道的5个洞段进行了围岩分级,分级结果与模糊层次分析等方法的结果相符,表明了该方法在隧道围岩分级中的可行性和可靠性,为隧道围岩分级提供了新思路。     

基于AHP的地铁隧道防排水型式设计及应用研究

对地铁隧道防排水型式进行合理的评价及选择,是减少运营期间隧道渗漏水的有效途径。以往对隧道防排水型式的选择基本上都是采用隧道涌水量这一单一因素进行评价和分析,尚缺乏对排水型式的综合评价系统研究。文章在已有地铁隧道防排水设计研究的基础上,提出基于AHP法的地铁隧道防排水型式判断系统,建立层次分析评价数学模型,确定影响地铁隧道防排水影响因素的层次指标权重,根据建立的防排水型隧道的判断准则及标准,实现防排水型式选择的定量化。工程实例表明,建立的模糊综合评价方法与实际情况相符。由于影响因素的隶属度和权值依赖于评估或经验,其推广应用还需进一步研究并结合实体工程进行验证。     

Dynamic control and traffic performance in a freeway corridor: a simulation study

This paper describes simulation studies that were conducted to assess the performance of a freeway corridor control system. The system combines an advanced traffic management system with a motorist information system that provides route guidance to individual drivers. It has a hierarchical structure: The corridor level control acts in a supervisory capacity dynamically allocating traffic among alternative corridor facilities, including freeways, frontage roads, and signalized arterials. The local level control then selects control parameters for the individual facilities based on the predicted usage at the corridor level. A user specified performance function is optimized in the process. Both recurrent and nonrecurrent congestion scenarios were simulated using the SCOT model as a test bed. It is shown that, in most cases, significant benefits in performance can be obtained when the system operates as designed.     

Characterization of driving patterns and development of a driving cycle in a military area

This study develops a gradient-sensitive driving cycle for vehicles in military areas with paved and unpaved roads over steep and undulating terrain. The methodology develops the driving cycle using micro-trips extracted from real-world data taking into account factors that affect fuel consumption. The accuracy of cycle depended on the root mean square error and information value.     

Competition and disruption in a dynamic urban supply chain

Rapid changes and complexities in business environments have stressed the importance of interactions between partners and competitors, leading supply chains to become the most important element of contemporary business environments. There is a concomitant need for foresight in describing supply chain performance in all operating environments, including those involving punctuated disruptions. Furthermore, the urban metropolis is now widely recognized to be an environment which is especially vulnerable to supply chain disruptions and for which integrated supply chain decisions can produce very substantial net benefits. Accordingly, this paper presents a dynamic supply chain network model formulated as a differential variational inequality; the model is fashioned to allow consideration of supply chain disruption threats to producers, freight carriers, and retail enterprises. The DVI is solved using a fixed-point algorithm, and a simple numerical example, introduced to illustrate how the impacts of supply chain disruptions may be quantified, is presented.     

Vehicle electrification in a developing country: Status and issue,from a well-to-wheel perspective

The increase of public attention, scientific research and political interest in environmental problems associated with transportation has provided the motivation for re-invention of electric vehicles. However the usage of grid-dependent EVs with a high-carbon electricity grid might produce more damage to the environment. This study aims to provide an environmental impact comparison of ICEVs, HEVs and EVs during their usage cycle, by modeling their energy consumption (electricity or fuel) and the supply chains of the supplied energy, (well-to-wheel) based on a life cycle assessment. The results show that running EVs with the existing mixed sources of electrical energy produce larger impacts on the environment 60% of the time; when compared to HEVs. When compared to ICEVs, EVs produce a larger environmental impact on 7 out of 15 environmental impact categories. Overall the environmental impacts of EVs are substantial based on the well-to-wheel analysis. It will continue to be so if no change is made to the methods of electricity generation in the near future. Given that the environmental profile of EVs is linked with the existing national electricity generation mix, the national electricity supply must be made cleaner before the electrification of the urban transport system.     

盾构隧道的爆破施工监测与安全防护

城市地铁盾构穿越上软下硬地层施工中,通常采取爆破方案对基岩进行处理.文章针对施工现场地处深圳市5A级主要大型主题乐园欢乐谷内的盾构工程,对在建构筑物和已建成构筑物的安全防护提出了一些关于爆破施工中地上、地下安全防护与监测的思路和解决办法.     

Traffic rationing and pricing in a linear monocentric city

This paper presents a simple spatial equilibrium model for a linear monocentric city to investigate the effects of rationing and pricing on morning commuters' travel cost and modal choice behavior in each location. Under rationing and pricing, every day in the morning peak hour, each commuter is classified as either “free” or “rationed”. “Free” commuters are allowed to use the highway without paying the toll, whereas “rationed” commuters can avoid the toll only if they travel by transit. Each day, a fraction of commuters are rationed in their free use of the highway, and the rationing fractions are determined systematically so that everyone is equally rationed in a given period. It is found that Pareto‐improving rationing and pricing scheme might be obtained as a combination of the rationing degree and the toll associated with rationing. Extension to the rationing and pricing scheme with cordon and park‐and‐ride service has been made. Cordon and park‐and‐ride might help in improving the efficiency of rationing and pricing strategy although remains its Pareto‐improving property. Copyright © 2012 John Wiley & Sons, Ltd.     

Development of a signal-head-free intersection control logic in a fully connected and autonomous vehicle environment

Establishment of effective cooperation between vehicles and transportation infrastructure improves travel reliability in urban transportation networks. Lack of collaboration, however, exacerbates congestion due mainly to frequent stops at signalized intersections. It is beneficial to develop a control logic that collects basic safety message from approaching connected and autonomous vehicles and guarantees efficient intersection operations with safe and incident free vehicle maneuvers. In this paper, a signal-head-free intersection control logic is formulated into a dynamic programming model that aims to maximize the intersection throughput. A stochastic look-ahead technique is proposed based on Monte Carlo tree search algorithm to determine the near-optimal actions (i.e., acceleration rates) over time to prevent movement conflicts. Our numerical results confirm that the proposed technique can solve the problem efficiently and addresses the consequences of existing traffic signals. The proposed approach, while completely avoids incidents at intersections, significantly reduces travel time (ranging between 59.4% and 83.7% when compared to fixed-time and fully-actuated control strategies) at intersections under various demand patterns.     

Adding a new station and a road link to a road–rail network in the presence of modal competition

In this paper we study the problem of locating a new station on an existing rail corridor and a new junction on an existing road network, and connecting them with a new road segment under a budget constraint. We consider three objective functions and the corresponding optimization problems, which are modeled by means of mixed integer non-linear programs. For small instances, the models can be solved directly by a standard solver. For large instances, an enumerative algorithm based on a discretization of the problem is proposed. Computational experiments show that the latter approach yields high quality solutions within short computing times.     

复杂环境下浅埋隧道的爆破震动监测与控制技术

深圳地铁5号线和7号线在太安站—怡景站区间为浅埋暗挖隧道,地表建筑物密集,按规范规定必须在爆破施工的同时进行震动监测,以保证施工环境的安全.文章选取了有代表性的监测断面,对其监测数据进行了分析,得出了沿隧道径向和法向的震动规律:径向上,在掌子面(0测点)两侧对称的测点的震动速度规律反映为成洞区大于开挖区;法向上,以掌子面(0测点)为中心,往两个方向呈现震速下降的趋势,而且近似线性下降.分析结果表明,采用密集减震孔和竹节的减震方法能够起到明显的减震效果,径向的减震效果比法向的要好.