两种高速公路软土路基处理方法的应用分析

软土地基的复杂性、试验技术的准确度以及固结理论在设计计算中还存在一些问题。并且,各种软土地基的处理方法也都有一定的适用性和局限性。因此对软基的处理需因地制宜地采取相应的处理措施。结合工程实例,对袋装砂井加土工布和水泥粉喷桩两种处理方法的应用效果进行分析。     

浅谈钢带增强波纹管在吹填土地基的应用

人工吹沙填海形成的陆域属于欠固结的砂性地基,土质以中粗砂为主,地基具有地下水位高、地下水腐蚀性强、砂基含水率大、沉降未稳定等特点,采用何种适应性强、便于施工、耐久性好且兼具经济性的排水管道方案是吹填形成陆域基础设施建设的难题之一。文章以钦州保税港区一期雨水管道工程为实例,介绍了钢带增强波纹管使用于在吹填土地基的特点,为该种管材在类似地质环境条件中的推广应用提供参考。     

某港口饱和软土地基加固效果分析

文章以某港口软土地基加固工程为例,介绍采用塑料排水板＋吹填砂堆载预压加固处理方法,通过现场的监测资料、加固前后的室内试验和原位测试资料的分析对比,结果表明软土地基的加固效果显著。为同类工程的设计和施工提供参考。     

孔隙水压力观测在强夯法地基处理中的应用

文章通过对A码头地基处理工程强夯过程中超静孔隙水压力随夯击次数、深度、距离的变化规律及在各土层中的增长与消散规律的研究,确定强夯次数、夯点布置、加固影响深度等强夯参数,计算地基固结情况,确定两遍强夯的间隔时间,分析孔隙水压力观测在地基处理工程中的应用。     

以固结排水法确定砂井间距的分析方法

文章结合工程实例,分析了砂井间距对软基固结度的影响,提出了以固结排水法确定砂井间距的分析方法。该分析方法是根据具体的工况条件和软土的变形特性进行工后沉降分析,得到满足软基工后沉降要求所需的固结度后,再根据软土的固结特性和工期要求分析确定砂井间距。实例分析结果表明,该方法确定的砂井间距是合理的,取得了较好的技术经济效果。     

软弱吹填土地区管沟埋设技术分析

文章基于对钦州保税港吹填土地基地质情况的深入调查,阐述了管道开挖与回填的主要技术问题,并通过对比分析当前各种管沟埋设方案的优缺点,针对未经地基处理的地段开挖埋管,提出采用钢板桩+振动水密法综合处治的新思路,为吹填土地区或高水位软土砂基管道开挖埋设方案的选择提供技术参考。     

地铁荷载作用下水泥土应变监测模型试验研究

在软粘土地区修建地铁等工程中,采用水泥土加固法可有效提高地基强度,减小地基沉降,因而其得到了广泛应用。在施工过程中,由于扰动影响使得复合土体存在初始固结度,在循环荷载作用下其应变发展规律会存在一定差异,进而影响其长期变形。文章通过室内GDS动三轴试验对水泥土进行了动力测试,分析了水泥掺入比和初始固结度对其应变发展的影响。综合已有研究和试验结果,建立了考虑掺入比和初始固结度的应变发展模型。试验结果表明:初始固结度低的试样,应变发展速率越快;当初始固结度较低时,掺入比小的水泥土应变发展速率较快;水泥土应变发展呈非破坏型,不同固结度下水泥土的动应变与循环次数的对数lg N之间近似呈线性关系。     

塑料排水板在沿海区域软土地基处理中的应用

文章针对广西沿海区域软土地基的工程特性,分析了在沿海区域公路工程中使用塑料排水板处理软基工程的设计要点与计算要点,介绍了塑料排水板的施工工艺与质量保障措施,并结合工程实例对该软土地基内的孔隙水压力、地表沉降进行监测,评析塑料排水板的处理效果,为类似地基处理工程应用提供依据.     

考虑施工扰动影响下地铁工后沉降及孔压变化数值分析

目前,地铁施工引起的地基土变形和孔压变化已受到广泛重视。文章依据Henkel提出的三向应力条件下的超孔隙水压力理论,求得隧道起拱线处初始超孔隙水压力,通过MIDAS-GTS建立三维有限元模型,对杭州地铁工后固结进行数值模拟,分析了受施工扰动影响的工后不同时间段内地基土沉降和孔压分布规律。结果表明:施工完成后,土体中的超孔压分布呈左右对称分布,且孔压的消散程度与地基土固结度基本一致;固结沉降主要发生在盾构掘进初期,最大值出现在地表处;固结度越高,由地铁运行所引起的孔压变化量越小。     

广西水运工程地基承载力检测方法探讨

广西沿海工程地基多为清淤吹填砂和回填开山土形成,常用的检测方法是标准贯入试验和浅层载荷板试验。文章分析了标准贯入试验的影响因素并验证经验公式的适用性,探讨了浅层平板载荷试验的压板尺寸和反力平台的影响,研究适用于广西水运工程的地基承载力检测方法。     

A Lagrangian relaxation based heuristic for the consolidation problem of airfreight forwarders

International air cargo is an operation-intensive industry, involving complex procedures and many players. As an important player, airfreight forwarders need to consolidate the collected goods skillfully in order to satisfy the requirements of the shippers and, at the same time minimize the expense charged by the airlines. However, the air cargo rate structure is very complicated, making the consolidation a difficult mixed-integer programming problem for the airfreight forwarder. In this paper, the consolidation problem is first transformed into a well-known set covering problem by treating a feasible consolidated shipment as a set. Lagrangian Relaxation is used as the backbone to develop a recursive heuristic algorithm. Based on the numerical experiment, the heuristic algorithm generates solutions very close to optimality. In particular, a sensitivity analysis is performed with respect to the degree of concavity. The results suggest that the solution algorithm can be used as a core module of the decision support system for air cargo consolidation.     

大跨径连续梁临时固结设计探讨

临时固结是连续梁桥设计施工的关键,文章针对大跨径宽箱连续梁进行了临时固结设计,并通过计算分析,验证了该临时固结设计方案满足该类型桥梁的施工要求,为类似桥梁的临时固结设计提供了思路。     

大跨浅埋隧道极软岩富水界面综合施工技术

针对大跨浅埋隧道极软岩富水界面段施工,传统处理方法多为帷幕注浆固结,但此种工法存在施工周期长、工程造价高等缺点。兰渝铁路咀头隧道在此地质施工时,针对隧道埋深浅的特点,采用地表高压旋喷加固,结合洞内分部开挖、φ89钢管锁脚配合强支护参数等综合措施,达到了快速、安全、经济施工,对类似工程的施工有一定的借鉴和参考价值。     

Combining pickups and deliveries in vehicle routing – An assessment of carbon emission effects

This paper studies the effect on carbon emissions of consolidation of shipments on trucks. New positioning and communication technologies, as well as decision support systems for vehicle routing, enable better utilization of vehicle capacity, reduced travel distance, and thereby carbon emission reductions. We present a novel carbon emission analysis method that determines the emission savings obtained by an individual transport provider, who receives customer orders for outbound deliveries as well as pickup orders from supply locations. The transport provider can improve vehicle utilization by performing pickups and deliveries jointly instead of using separate trucks. In our model we assume that the transport provider minimizes costs by use of a tool that calculates detailed vehicle routing plans, i.e., an assignment of each transport order to a specific vehicle in the fleet, and the sequence of customer visit for each vehicle. We compare a basic set-up, in which pickups and deliveries are segregated and performed with separate vehicles, with two consolidation set-ups where pickups and deliveries may be mixed more or less freely on a single vehicle. By allowing mixing, the average vehicle load will increase and the total driven distance will decrease. To compare carbon emissions for the three set-ups, we use a carbon assessment method that uses the distance driven and the average load factor. An increase in the load factor can reduce part of the emission savings from consolidation. We find that emission savings are relatively large in case of small vehicles and for delivery and pickup locations that are relatively far from the depot. However, if a truck visits many demand and supply locations before returning to the depot, we observe negligible carbon emission decreases or even emission increases for consolidation set-ups, meaning that in such cases investing in consolidation through joint pickups and deliveries may not be effective. The results of our study will be useful for transport users and providers, policymakers, as well as vehicle routing technology vendors.     

悬浇连续梁墩梁临时固结技术的验算与应用

广西靖西至那坡高速公路百大特大桥采取临时固结的方式进行预埋粗钢筋锚固施工,文章结合该工程实例,通过建立简支双悬臂结构在四种荷载工况下的计算模型,分析了悬臂浇注连续箱梁施工临时固结的最不利荷载工况,以及在此工况下临时支座的受力情况,并对临时支座及临时锚筋进行了相应的结构计算。     

超深搅拌桩施工技术及应用

详细介绍了上海轨道交通9号线二期工程源深路中间风井施工中超深搅拌桩加接钻杆的施工技术、工艺及监测结果。应用60m超深搅拌桩进行土体加固取得成功，从而在地基加固工程中的应用越来越广泛，是一种很有推广前景的施工工艺。     

A dynamic empty equipment and crew allocation model for long-haul networks

This research develops a realistic and efficient operational model to optimize empty equipment and crew movements in long-haul trucking networks with consolidation, where returning drivers home within a reasonable amount of time is an important issue. The problem can be stated as follows. On a network of consolidation centers, demand is expressed as a set of trailer-loads that need to be moved between each pair of consolidation centers in each time period and the objective is to optimize trailer, tractor and driver movements while ensuring that drivers return home within a pre-determined period of time. In this paper, a dynamic integer programming model is developed and an efficient approximate solution method is proposed, which involves column generation and branch-and-bound. The algorithm switches from a combination of network and primal simplex to dual simplex to overcome the degeneracy problem, which is very common for dynamic networks. This novel approach enables solving large problems with many intervals. We solved problems with up to 30 nodes and 48 periods successfully by using real data provided by a less-than-truckload company, and by generating statistical forecasts based on the real data.     

Traffic consolidation in East Asian container ports: A network flow analysis

The proliferation of hub-and-spoke operations in maritime container transportation has resulted in the widespread consolidation of traffic flows. Utilising liner shipping network configurations, this paper assesses the impact of freight traffic consolidation in the container port industry by exploring the spatial pattern of traffic flow movements and identifying the variety of roles that container ports play within this context. On the basis of the network concept, the spatial inequality of freight traffic consolidation is determined by the density and direction of all meaningful connections (i.e. significant flows) identified by applying Multiple Linkage Analysis (MLA) to an initial traffic flow matrix.The effectiveness of the chosen methodology is tested empirically using a sample comprising the 18 major container ports in East Asia, together with another 21 important container ports located on the East–West trading route. Based on this sample network, the spatial structure of traffic flow consolidation reveals the nature and structure of hub-and-spoke operations within a port system, the relative hub-dependence of ports, the variety of roles which individual ports play within the overall structure of inter-port interactions and the hierarchical configuration of the port industry structure. The paper concludes that MLA offers new insights into the distributional inequality of traffic flows, the spatial and economic interactions between ports and the extent to which hinterlands overlap. Furthermore, the analysis clearly shows that inter-port relationships can no longer be evaluated as isolated phenomena; any change in a specific port’s competitiveness will directly impact upon the structure of the whole maritime transportation system. Port authorities and terminal operators will need, therefore, to carefully analyse and disentangle specific inter-port relationships in order to provide the most appropriate basis for their decision making.     

桥梁检测与加固技术

近年来，随着桥梁建设事业的飞速发展，桥梁结构的使用荷载日益增大，大批既有桥梁结构也进入了老化期，桥梁检测与加固由此越发显得重要。 多年来，西部交通建设科技项目管理中心进行了大量桥梁检测评定与加固技术的研究，所取得的系列成果及积累的经验表明：公路旧桥检测评定与加固技术的研究及推广不仅对规范公路旧桥加固改造市场、提升旧桥加固技术水平和质量品质是十分必要的，而且具有可观的经济效益和社会效应。本篇针对西部地区在桥梁检测与加固技术研究方面取得的部分成果进行介绍，以期推广应用。