CFG桩处治软土地基效果分析

针对公路软土地基CFG桩加固问题,文章依托实际工程,根据施工现场地质情况确定CFG桩软基加固施工参数,制定了加固方案,并在完工后进行静载试验和沉降监测分析。结果表明,地基承载力满足设计要求,路基水平位移和工后沉降逐步达到稳定,说明路基稳定性良好,达到了预期的加固效果。     

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。     

过湿复杂土环境下软土复合地基稳定性研究

文章以广西南宁某生态湿地公园湖心岛球场建设为背景,采用Plaxis 3D有限元软件建立复合地基三维固结模型,模拟分析了软土地基的沉降变形及安全性,对比研究了换填级配碎石垫层对软土地基稳定性的影响。结果表明：固结后各填筑阶段沉降整体增加了1～2 cm,应增加施工过程的排水措施;设置级配碎石垫层可以改善地基承载能力,降低工后沉降;软土地基的安全系数随着施工进程逐渐降低,为增强地基的稳定性应提高软土层的粘聚力。     

软基真空预压工后残余沉降量空间分布预测分析

工后残余沉降量是真空预压法处理软土地基的主要控制标准之一。然而受到土体非均质性的影响,填海工程中软基的工后残余沉降量往往表现出很大的空间变异性。文章对广州某填海工程试验区内软基的工后残余沉降量进行了分析,采用条件随机场预测了整个空间区域内工后残余沉降量的空间分布图,并据此计算出了工后残余沉降量超过允许值的概率分布图。根据该分布图,指出了真空预压需要延长加荷时间的区域,为真空预压卸荷方案设计提供了指导意见。     

堆载预压处理吹填砂软土地基的固结度分析

固结度是评价大面积吹填砂软土地基处理效果的一个重要指标。文章结合珠江某港口大面积吹砂与排水板堆载预压联合地基处理工程实践,从应变与应力两个方面分析了固结度的计算方法以及存在的问题,为类似工程中的固结度计算提供参考。     

浅论上三高速公路上虞段的软基处理

结合上三高速公路上虞段的软基处理中的实践,介绍、分析工程地质特征、软基处理的分类和作用,对解决软土地基的稳定性问题和减少工后沉降的治理措施提出具体方法.     

京沪高速公路改扩建软土路基处理技术及有限元分析

结合京沪高速公路改扩建工程,提出了浅层软基清淤换填、深层软基水泥搅拌桩复合地基和素混凝土桩复合地基为主的软基处理技术方案,并采用有限元方法计算分析改扩建软土路基的滑动稳定系数、工后沉降等,保障了改扩建工程软基处理技术的可靠性与合理性,为类似改扩建软基处理提出技术借鉴与经验。     

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.     

高速公路过渡段软土地基处理数值模拟研究

为研究水泥搅拌桩与塑料排水板处理的软土路基过渡段间差异沉降的影响因素,文章通过FLAC3D软件建立数值模型并进行计算分析,讨论填土高度、软土深度和水泥搅拌桩桩间距对软土路基过渡段差异沉降的影响,所得结论如下:(1)采取水泥搅拌桩和塑料排水板处理的两个软土路基段之间的沉降差异较为明显,水泥搅拌桩加固区域的工后沉降明显大于塑料排水板区域;(2)随着填土高度、软土深度和水泥搅拌桩桩间距的增大,水泥搅拌桩区域和塑料排水板区域的工后沉降均逐渐增大.过渡段的差异沉降值也在逐渐增大,水泥搅拌桩是否打穿软土地层对于地基加固效果有很大影响,同时增大桩间距会减弱水泥搅拌桩复合地基的加固效果。     

申苏浙皖高速公路薄壁筒桩处理软基施工技术

申苏浙皖高速公路(浙江段)部分软基路段设计采用薄壁筒桩处理方式,对减小软土地基高路堤桥头跳车效果十分明显,达到了减小路基工后沉降的目的.     

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.     

超载预压塑料排水板加固软土地基试验研究

文章以我国东部沿海某新建机场地基处理工程为背景,通过动态监测加固地基的地表沉降、差异沉降、分层沉降、侧向变形、地下水位及孔隙水压力,探讨超载预压塑料排水板加固软土地基的变形规律及效果,为类似工程的优化设计和安全施工提供科学依据。     

全断面富水砂层浅埋盾构隧道下穿平房群施工参数研究

盾构在富水砂层中掘进时,容易出现喷涌、地表沉降大、流砂等现象,给掘进施工带来很多问题和困难,尤其是在全断面富水砂层中掘进时,如何控制盾构施工参数显得极其重要。文章结合广州地铁21号线水西站—长平站盾构区间隧道工程实例,考虑了工程实践中盾构穿越全断面富水砂层且下穿薄弱基础的水西村民房建筑的情况,进行了盾构施工措施及试验段掘进参数分析,确定了盾构下穿水西村民房建筑的施工参数。监测结果表明:参数实际控制值与分析拟定值接近,地表沉降可以控制在5 mm内,房屋沉降可以控制在10 mm内,验证了参数选取的正确性。盾构在全断面富水砂层中下穿平房群时,实际土舱压力高于静止土压力,同步注浆量不低于1.6倍的理论值,提高土压力和推力可以有效降低平房群的沉降值。     

Effects of demurrage and detention regimes on dry-port-based inland container transport

Increase of congestion at container deep seaports and shortage of capacity has led inland transport systems worldwide to rely more and more on inland terminals, and on the use of high capacity modes of transport to generate economies of scale and reduce negative effects of trucking. In this setting, planning the transport of maritime containers between a deep seaport and a final inland destination must also consider due dates and soft time windows, the latter known as Demurrage and Detention (D&D). In this paper, we formalize the concept of D&D, model the multimodal planning problem, and assess the impact of different D&D regimes on the emerging inland transport systems. By means of an experimental framework, we compare different D&D policies and provide managerial insights. The experiments highlight the effects of existing D&D regimes on transport efficiency and provide guidelines for their choice in practice. D&D are shown to have a twofold effect: first to limit consolidation opportunities and force the use of trucks as buffer, and second to push containers to dwell unnecessarily at the seaports.     

沉降速率法在软基沉降分析中的应用

文章结合国内沿海某机场飞行区扩建项目软基处理工程实例，对比分析了双曲线法、三点法、Asaoka法和沉降速率法的主固结沉降量推算结果，指出了沉降速率法的优势，并应用沉降速率法准确的进行了沉降预测和卸载时间预测。     

Hybrid predictive control for real-time optimization of public transport systems’ operations based on evolutionary multi-objective optimization

A hybrid predictive control formulation based on evolutionary multi-objective optimization to optimize real-time operations of public transport systems is presented. The state space model includes bus position, expected load and arrival time at stops. The system is based on discrete events, and the possible operator control actions are: holding vehicles at stations and skipping some stations. The controller (operator) pursues the minimization of a dynamic objective function to generate better operational decisions under uncertain demand at bus stops. In this work, a multi-objective approach is conducted to include different goals in the optimization process that could be opposite. In this case, the optimization was defined in terms of two objectives: waiting time minimization on one side, and impact of the strategies on the other. A genetic algorithm method is proposed to solve the multi-objective dynamic problem. From the conducted experiments considering a single bus line corridor, we found that the two objectives are opposite but with a certain degree of overlapping, in the sense that in all cases both objectives significantly improve the level of service with respect to the open-loop scenario by regularizing the headways. On average, the observed trade-off validates the proposed multi-objective methodology for the studied system, allowing dynamically finding the pseudo-optimal Pareto front and making real-time decisions based on different optimization criteria reflected in the proposed objective function compounds.     

Analysis on Ground Surface Deformation and Influence of Construction Parameters Caused by Two Different Shield Machines in Double-tube Tunnelling北大核心CSCD

Based on a shield-driven running tunnel project of Hangzhou Metro Line 2, this paper carries out field measuring of the ground surface deformation caused by two different shield machines in double-tube tunnelling in soft soil areas, obtains the laws of the surface deformation caused by shield-driven double-tube tunnelling and verifies the applicability of the modified Peck formula to double-tube tunnelling. The results show that in soft soil areas the impacts on ground surface deformation caused by different shield construction parameters in the previously and subsequently excavated tunnels are different, while the surface deformation changes sharply before and after the shield machine passing through the cutting face, and a rebound phenomenon occurs when the shield tail passes through the cutting face due to the influence of the grouting; The cutterhead torque of the shield machine in soft soil areas can be composed of five calculation factors, and the calculation results are in good agreement with the measured values. The larger the opening rate of the shield cutterhead is, the larger the average torque value will be, the higher the percentage of large ground loss rate will be, and the larger the maximum ground surface settlement will be; The ratio of cutterhead torque T to mucking volume per ring Q is used as the control parameter for analyzing the ground surface settlement, and a certain positive correlation between the ratio and the surface settlement value is determined, the smaller the cutterhead opening rate is, the more accurate the fitting results will be. © 2022, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

路基沉降变形预测方法及应用实例分析

对路基沉降变形的计算和预测方法中的双曲线预测模型及原理进行介绍,结合浙江某高速公路路基沉降变形预测的实例进行分析,实测数据与相对应的预测曲线吻合度较好,客观地反映了路基沉降的动态发展情况。