The price of uncertainty in pavement infrastructure management planning: An integer programming approach

Currently there is a true dichotomy in the pavement maintenance and rehabilitation (M&R) literature. On the one hand, there are integer programming-based models that assume that parameters are deterministically known. On the other extreme, there are stochastic models, with the most popular class being based on the theory of Markov decision processes that are able to account for various sources of uncertainties observed in the real-world. In this paper, we present an integer programming-based alternative to account for these uncertainties. A critical feature of the proposed models is that they provide – a priori – probabilistic guarantees that the prescribed M&R decisions would result in pavement condition scores that are above their critical service levels, using minimal assumptions regarding the sources of uncertainty. By construction of the models, we can easily determine the additional budget requirements when additional sources of uncertainty are considered, starting from a fully deterministic model. We have coined this additional budget requirement the price of uncertainty to distinguish from previous related work where additional budget requirements were studied due to parameter uncertainties in stochastic models. A numerical case study presents valuable insights into the price of uncertainty and shows that it can be large.     

Potential of a repair system for grouted connections in offshore structures: Development and experimental verification

Grouted connections are intensively used in offshore rigs, platforms as well as jacket and monopile offshore wind turbine structures. Being located in remote offshore conditions, these connections can experience considerable adverse loading during their lifetimes. Degradation was reported inside similar connections, which were installed in the last three decades. Grouting in the offshore sites may often be proven difficult, which eventually leads to reduced load-bearing capacity of connections in the long run. Thus, repair and rehabilitation of such connections should be planned ahead to minimize operational delays and costs. In this study, scaled grouted connections were manufactured using a novel mould, whose integrity were monitored using digital image correlation (DIC). The connections were loaded under static load to visualize the main failure pattern using distributed fibre optic sensors and acoustic emission (AE) analysis. Grouted connections were then repaired using a cementitious injectable grout. The effectiveness of the grout injection was monitored using dye penetration technique. Finally, specimens are reloaded to identify the potential of such repair for grouted connections.     

进口汽车曲轴轴颈磨损的电刷镀修复

进口汽车的曲轴价格昂贵，磨损后在没有配件的情况下可采用电刷镀技术来修复。对于进口汽车来说，产生曲轴磨损的主要原因是：用户对进口汽车的维修使用要求不够了解，添加润滑油时降低了标准，油道被堵塞，轴瓦缺油被烧伤磨轴颈，或维修时未按装置要求操作，使曲轴各道轴颈松紧程度不均，装配过紧处，使曲轴润滑油膜太薄，或无法形成油膜，造成烧伤磨损。在电刷镀时，只要正确执行刷镀工艺就可将曲轴修复。     

既有混凝土桥梁结构病害缺陷分析与处理

本文通过几个地区旧桥运营情况的调查结果,对目前混凝土桥梁结构所存在的主要病害进行了较全面的分析,并提出了相应的处治措施。同时结合井冈山大桥的维修加固工程实例,介绍了各病害处治措施的综合应用情况,取得了较好的加固效果。     

高速公路沥青路面早期车辙病害处治技术方案研究

通过对南方某高速公路早期车辙病害调查和试验分析,发现沥青路面早期车辙与路面材料抗车辙能力差和施工质量控制不严有关,路面车辙仍继续发展,并逐渐向沥青中下面层发展。结合路面车辙产生原因及其特点,铺筑了4个处治方案试验路,并对其使用效果进行了观测。根据观测结果,对路面处治方案使用效果进行了分析评价,并提出了后续全线车辙处治技术方案。     

水泥混凝土路面断板的原因与处治研究

本文对水泥混凝土路面断板进行了分类，并认真分析了各种路面断板的原因，针对断板病害，经过研究提出了一些预防措施和修复处治方案。     

浅谈土工布在路面病害处理中的应用

详细阐述了在公路工程路面病害修补中,采用无纺土工布和玻纤网两种土工合成材料,能有效减缓沥青混凝土面层裂缝的产生,对土工布的特点和施工工艺应用效果进行了分析和研究。     

水下隧道修复方案及安全性分析

文章基于某水下盾构隧道因涌砂招致破坏后进行修复并继续使用的工程实例,详细阐述了套管法修复施工方案的工艺流程,并通过三维有限元模型对套管法修复施工过程进行了安全性分析。结果表明:采用液压振动锤施作外套管时其冲击力对下方既有隧道的影响不大,但需要对该施工过程进行计算校核;隧道变形和应力最大值基本发生在隧道顶部开口处,需要注意加强结构受力分析和止水措施。     

Rehabilitating the Mangrove Resources of Cogtong Bay,Philippines: A Comanagement Perspective

The local management of mangrove resources in Cogtong Bay, Philippines, dates back to the 1940s and 1950s when some families informally designated mangrove areas under their care and management. The 1960s and 1970s saw several exogenous events that led to the progressive denudation of mangrove stands and the decline in fish catch per fishing trip. This article draws attention to the forces that prompted coastal villages and external agents to collaborate with the national and local government units in resource rehabilitation. It also assesses the performance of a coastal resources comanagement project at Cogtong Bay.     

高速公路沥青路面养护与维修方案的选择与设计

描述系统化的高速公路沥青路面养护与维修方案选择和设计的过程和方法,包括数据的需求采集、现有路况的定性定量评价、养护措施的选择、可行养护与维修方案的生成和设计、备选方案的评估等。由于高速公路具有交通量大、社会影响大的特点,文中重点提出在选择维修方案过程中,需预先分析与不同维修方案相关的交通控制策略及施工规划组织,以对不同可行方案进行全面的评估,从中选取最佳的维修养护方案。