冻结法在隧道下穿既有建(构)筑物中的应用

采用矿山法在富水复合地层中施工时,传统工法封水效果差,变形较难控制,容易对地面建(构)筑物产生破坏。冻结法具有对环境干扰小、加固效果好、可操作性强等优点。隧道下穿既有建(构)筑物时采用冻结法对地层进行封水及加固处理后将大大减少隧道开挖时对上部建(构)筑物的扰动,确保施工安全。结合深圳轨道交通7号线福邻站工程,介绍和分析了冻结法在下穿施工既有地面建(构)筑物中的应用。     

广州地铁六号线黄花岗至沙河顶暗挖区间下穿内环路技术方案研究

城市轨道交通工程下穿重要交通要道、建(构)筑物是不可避免的,工程自身和周边建(构)筑的安全控制非常困难.文章结合广州地铁六号线黄花岗站至沙河顶站暗挖区间下穿市内环路段工程所遇到的隧道超浅埋、围岩稳定性差、周边建(构)筑物保护难等问题进行了分析,通过采用钢便桥、WSS全断面注浆、大管棚、CD工法等措施,有效解决了超浅埋隧道施工及周边建筑保护中的相关问题.     

盾构直接切削及托换后切削建筑物桩基施工技术

文章以深圳市城市轨道交通9号线鹿丹村站—人民南站—向西村站区间隧道工程为背景,论述两种不同工况下盾构切削建(构)筑物桩基施工技术,施工中通过对总推力、推进速度、刀盘扭矩、土压等参数的控制,不仅顺利地切削和穿越了桩基,而且很好地控制了地表及周边建(构)筑物的沉降,达到了对周边环境影响小、缩短施工周期、降低造价的目的,可为类似工程提供一定借鉴。     

借助既有结构进行天桥吊装对邻近建（构）筑物影响分析

上海金沙江路真北路人行天桥结构分块吊装需设置较多临时支撑及桩基,桩基距离既有地道、车站及区间隧道距离较近。在中环金沙江路地道光过渡段中隔墙上设置临时支撑,借助既有建（构）筑物结构进行吊装施工。对此施工方案进行了数值模拟和分析,以评估其对邻近既有地下建（构）筑物的影响程度。     

深孔注浆技术在地铁暗挖隧道施工中的应用

城市地铁暗挖隧道施工中所面临的难题之一就是水的治理问题,水不仅危及掌子面开挖作业的安全,同样也威胁到地面建(构)筑物的安全。面对富水砂层及软弱破碎层,如何进行掌子面加固及止水是施工的关键。深圳地铁2号线东延线2222标安-侨区间隧道工程中采用TGRM深孔注浆技术成功地完成了富水砂层段的施工以及近距离多次穿越重要管线及建(构)筑物的施工,充分表明在不良地质地段采用深孔超前预注浆加固掌子面及固结止水技术是行之有效的。文章针对此工程实例,阐述了深孔注浆技术的机理和工艺特点,以及在城市暗挖地铁隧道施工中的应用效果。     

支撑体系静音切割拆除工艺的应用与探讨

支撑体系的拆除对工程在建部分和周围建(构)筑物的安全影响较大。以上海轨道交通14号线黄陂南路站西端头井支撑体系拆除为例,为减小对在建工程和周边建(构)筑物的影响,采用静音切割工艺。该工艺实现了无振动切割和钢筋混凝土的逐一研磨分离,具有施工作业速度快、噪声低、无振动、无粉尘废气污染、无需善后加工处理等特点,为后续工作提供了方便,既解决了结构的安全性问题,也解决了施工工期及环保问题。介绍和分析了支撑体系静音切割拆除的施工工艺及施工方法,为类似工程提供借鉴。     

敏感环境下明挖隧道设计方案研究

穿越城市等敏感环境的明挖隧道是一项风险高、难度大的系统工程,需要在充分掌握地质资料、全面分析对周边建(构)筑物影响的基础上,制定出合理的围护结构支护体系和加固工程措施。文章以南宁-崇左城际铁路项目留村工程明挖段为例,通过分析研究地质资料和周边建(构)筑物关系,系统性地介绍了敏感环境下选用围护结构支护体系和加固工程措施的方法和过程,为类似工程建设提供参考。     

上海外滩通道超大直径土压平衡盾构施工技术

针对上海外滩通道圆隧道工程的特点及施工难点,介绍了通过采取隔离桩、土体改良以及控制盾构正面土压力等一系列有效的施工技术措施,使直径14．27m土压平衡盾构顺利下穿外滩万国建筑群及外白渡桥、轨道交通2号线、南京东路人行地道和北京东路人行地道等建（构）筑物,为今后超大直径土压盾构施工提供借鉴。     

盾构下穿建(构)筑物控制沉降注浆技术研究与应用

北京地铁黄村站-义和庄站区间隧道采用盾构法施工,由于下穿建(构)筑物群及12股轨道群,施工中在地面不具备加固条件的情况下采用了隧道内部超前注浆和径向注浆加固措施,即通过盾构机的8个超前注浆孔对刀盘前上方土体进行加固,在盾构机头过后利用管片上的预留注浆孔及时对隧道上方土体进行深孔注浆加固,有效地控制了地面建(构)筑物的最终沉降量.文章对本工程的概况、地层沉降机理、注浆措施及对沉降的控制效果进行了研究和分析.     

大型深沉井在复杂环境中排水下沉的探讨

白龙港WAM/1.1标浦西倒虹井地处复杂环境中，采用沉井法施工。施工中通过采取科学有效的技术措施，将沉井排水下沉至标高-20.18m，并确保了周围重要建（构）筑物的安全。以此工程为例，主要阐述沉井施工过程中的难点、采取的措施和取得的成效，为今后同类工程的施工提供借鉴。     

苏州地铁工程风险评估及处置对策初探

针对苏州地铁工程建设中现有的影响工程风险等级划分的因素、风险等级划分方法及可用的处置方法,提出将工程周边环境现状结构质量和重要性程度,以及车站围护形式作为风险等级划分的重要因素等建议.结合苏州地铁某车站的工程实例,介绍了工程风险评估及处置对策.     

Quantitative analysis of passenger and baggage security screening at airports

The terrorist attacks in the United States in 2001 opened a new era in air transportation. The realization that civil aircraft can be used as powerful weapons of mass destruction by a small group of people has drastically increased the need for security screening procedures to protect civil flights. Serving as the interface between the air and land transportation modes, airports have become the main focus in the implementation of those procedures. The need to more thoroughly screen passengers and baggage, and the consequent increase in processing time, has created the need for more space for security checkpoints and baggage screening inside passenger terminal buildings—space that is costly and very difficult to find in existing buildings. This paper evaluates the impact those measures have had on the planning and operation of airport passenger terminals. Quantification of those impacts is performed with the use of discrete‐event simulation and spreadsheet models.     

Estimation of airport noise impacts on public health. A case study of İzmir Adnan Menderes Airport

The air transport industry is showing rapid growth in line with the call for meeting the requirements of a rising population. Noise mapping is more useful than surveys and measurements to estimate the effects of noise on public health. In this paper, noise levels for the day, evening and night time slices around İzmir Adnan Menderes Airport were calculated by use of the SoundPLAN 7.2 software according to the European Noise Directive, and the “ECAC Doc. 29-Interim” method was applied for the computation of the aircraft noise. Air traffic data of year 2012, technical information about the airport and geographical data including the layers of elevation, residential buildings, auxiliary buildings, hospitals and schools were used as the main inputs for the model developed in the study. The model was found to perform well for the areas closer to the airport. The results of the study suggested that the area at the north side of the airport, where the city center of İzmir is located, is more affected than other areas. The threshold value of 55 dB(A) was found to be exceeded in 0.3% of the land area covered by İzmir City center during the time slice “day”. The results showed that about 2% of the resident population was exposed to noise levels of 55 dB(A) or higher during day-time in İzmir. In addition, it was understood that the number of people who are potentially exposed to high noise levels and threatened by several illness such as hypertension and sleep disturbances is significant in the surrounding area of the airport. It is thought to be important for airport operators to manage the airport capacity based on the flight schedules in order to control the noise exposure level around the airport.     

大跨浅埋公路隧道下穿既有建筑施工的沉降控制

厦门机场下穿34号楼隧道工程,隧顶到建筑结构底3 m,属浅埋大跨下穿既有建筑物连拱隧道工程.论文根据工程类比法,采用CRD法优化隧道施工步骤;借助数值分析方法,分析既有建筑的沉降规律,把握了CRD法重点施工步骤.根据现场实测及数值模拟结果,提出了超前注浆、地面硬化及补偿抬升注浆、洞内全断面帷幕注浆、大管棚超前支护等多种施工辅助措施.实践表明,施工过程中既有建筑结构沉降得到有效控制,最终沉降量小于40 mm.     

Confidence intervals of willingness-to-pay for random coefficient logit models

Random coefficient logit (RCL) models containing random parameters are increasingly used for modelling travel choices. Willingness-to-pay (WTP) measures, such as the value of travel time savings (VTTS) are, in the case of RCL models estimated in preference space, ratios of random parameters. In this paper we apply the Delta method to compute the confidence intervals of such WTP measures, taking into account the variance–covariance matrix of the estimates of the distributional parameters. The same Delta method can be applied when the model is estimated in WTP space. Compared to simulation methods such as proposed by Krinsky and Robb, the Delta method is able to avoid most of the simulations by deriving partly analytical expressions for the standard errors. Examples of such computations are shown for different combinations of random distributions.     

陕北冻土高水位流沙地段管沟开挖方法研究

高水位流沙地段的管沟开挖一直是施工过程中的难点,虽然目前可采用深井抽排降水法、密闭管抽水降水法、明渠抽排降水法、木桩固定沟壁加抽水降水法等方法,但施工工序繁琐,成本高。文中提出应用冻土原理,在一次双侧沉管的基础上,采用二次双侧开挖新方法,将地下高水位的挖沟不利条件变为有利条件,降低了土方开挖量,取消了抽排水措施,提高了施工工效,节约了施工成本。该方法在陕京三线设计1标段榆阳马家峁段AA001-AA005高水位流沙地段工程施工中取得了良好的施工工效与经济效益。     

Required traffic micro‐simulation runs for reliable multivariate performance estimates

Previous methods to calculate the minimum number of traffic micro‐simulation runs do not consider multiple measures of performance simultaneously at an overall confidence level, which can lead to unreliable simulation outputs. This paper describes new methodologies for calculating the minimum number of traffic micro‐simulation runs for multivariate estimates at an overall confidence level. Simultaneous confidence intervals obtained from multiple comparisons in statistical theory such as the Bonferroni inequality and simultaneous confidence interval method are used to estimate multiple measures of performance with allowable errors at an overall confidence level. Measures of performance can be means and standard deviations. Results of numerical analysis based on an example corridor suggest that the proposed methods provide improved means of assessing statistical accuracy of multiple measures of performance. Results also indicate that the minimum number of runs is influenced by not only the sample size issue but also the complexity of the traffic system. Copyright © 2015 John Wiley & Sons, Ltd.     

An integrated measure of accessibility and reliability of mass transit systems

The growth of a city or a metropolis requires well-functioning transit systems to accommodate the ensuing increase in travel demand. As a result, mass transit networks have to develop and expand from simple to complex topological systems over time to meet this demand. Such an evolution in the networks’ structure entails not only a change in network accessibility, but also a change in the level of network reliability on the part of stations and the entire system as well. Network accessibility and reliability are popular measures that have been widely applied to evaluate the resilience and vulnerability of a spatially networked system. However, the use of a single measure, either accessibility or reliability, provides different results, which demand an integrated measure to evaluate the network’s performance comprehensively. In this paper, we propose a set of integrated measures, named ACCREL (Integrated Accessibility and Reliability indicators) that considers both metrics in combination to evaluate a network’s performance and vulnerability. We apply the new measures for hypothetical mass transit system topologies, and a case study of the metro transit system in Seoul follows, highlighting the dynamics of network performance with four evolutionary stages. The main contribution of this study lies in the results from the experiments, which can be used to inform how transport network planning can be prepared to enhance the network functionality, thereby achieving a well-balanced, accessible, and reliable system. Insights on network vulnerability are also drawn for public transportation planners and spatial decision makers.     

Influences of built environment characteristics and individual factors on commuting distance: A multilevel mixture hazard modeling approach

Concerns over transportation energy consumption and green-household gas (GHG) emissions have prompted a growing body of research into the influence of built environment on travel behavior. Studies on the relationship between land use and travel behavior are often at a certain aggregated spatial unit such as traffic analysis zone (TAZ), spatial issues occur among individuals clustered within a zone because of the locational effects. However, recognition of the spatial issues in travel modeling was not sufficiently investigated yet. The object of this study is twofold. First, a multilevel hazard model was applied to accommodate the spatial context in which individuals generate commuting distance. Second, this research provides additional insights into examine the effects of socio-demographics and built environment on commuting distance. Using Washington metropolitan area as the case, the built environment measures were calculated for each TAZ. To estimate the model parameters, the robust maximum likelihood estimation method for a partial function was used, and the model results confirmed the important roles that played by the TAZ and individual level factors in influencing commuting distance. Meanwhile, a comparison among the general multilevel model, single level and multilevel hazard models was conducted. The results suggest that application of the multilevel hazard-based model obtains significant improvements over traditional model. The significant spatial heterogeneity parameter indicates that it is necessary to accommodate the spatial issues in the context of commuting distance. The results are expected to give urban planners a better understanding on how the TAZ and individual level factors influence the commuting distance, and consequently develop targeted countermeasures.     

软弱地层盾构斜穿既有建筑物沉降控制技术

文章以天津地铁九号线盾构穿越蝶桥公寓为背景,研究分析了软弱地层中浅埋盾构斜穿既有建筑物的安全风险和沉降控制措施.施工中由于采用了双液浆和单液浆组合注浆方式,有效地控制了地表沉降.监控量测结果表明,采用的综合措施,效果良好,可供类似工程借鉴.