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.     

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。     

独柱墩桥梁结构安全验算及处理方案探讨

针对近年来发生的多起独住墩桥梁倾覆事件和各地普遍存在的支座脱空等问题,结合工程实例开展了独住墩桥梁受力探讨。首先对比了交通部征求意见的抗倾覆验算方案,对主要存在以上问题的曲线桥梁分析了梁体扭转、支座脱空的原因,并根据计算结果提出相应的加固措施,在实际加固处理工程中取得了良好的效果,可为其他类似工程提供参考。     

高铁沿线地下水位动态变化引发的成层弱透水层固结研究

采用Laplace变换和传递矩阵法推导高铁沿线地下水位动态变化引发的成层弱透水层固结变形的解析解,通过与ABAQUS数值计算结果对比验证解析解的正确性。利用解析解对某高速铁路沿线成层弱透水层的固结性状进行研究,计算地下水位动态变化下土层的固结变形量、变形速率和超静孔隙水压力随时间的变化,并分析土层压缩模量和渗透系数对土层固结变形的影响。研究结果表明:随着地下水位降低,土层中孔隙水压力逐渐降低,土层固结变形量和变形速率逐渐增加;当地下水位保持稳定后,土层固结变形速率逐渐降低,但土层仍持续较长时间的固结过程;土层压缩模量越大,土层系统总沉降量和沉降速率越小;土层渗透系数越大,土层总沉降量越大,水位稳定后土层系统完成固结的时间越短。