移动式线路动态加载试验车的研制

通过分析国内外移动式线路动态加载试验车(装置)技术水平和现状,提出我国研制移动式线路动态加载试验车的目的和意义。介绍我国移动式线路动态加载试验车的主要功能和技术参数,并与国外同类设备进行比较,提出先进性、实用性、经济性研制原则。     

分布式光纤传感技术在岩溶段桩基检测中的应用研究

分布式光纤传感技术近年来广泛应用于土木工程领域,该技术具有分布式测量、耐久性好、施工方便等优点。本文将此技术应用于岩溶区灌注桩检测,研究岩溶区灌注桩荷载传递规律和桩身附近溶洞存在位置,通过钢筋应力计测量结果验证了光纤传感技术在岩溶区灌注桩检测中应用的可行性。结果表明,该技术可实现岩溶区灌注桩完整性的分布式检测功能,并能判断桩身周围溶洞存在位置区间。相对于钢筋应力计、应变片等传统的检测方法,分布式光纤传感技术具有更高的检测精度和更广的测量范围。     

动荷载作用下钢结构涂装的累积损伤机理与量化模型

为研究动荷载作用下公路钢桥涂装层与基体间的协同变形和破坏机制,开发了钢结构涂装层试件的动荷载试验系统,研究了疲劳荷载作用下涂层的破坏模式、附着力、弹性厚度、应变等随循环加载次数的发展规律。结合涂层破坏模式和发展规律,构建了涂层疲劳累积损伤度的计算模型,提出了基于损伤度的涂层破坏分级方法,并结合试验结果进行了验证。结果表明:疲劳荷载将引起涂层的附着力下降、弹性厚度降低和应变松弛,进而导致涂层出现附着破坏、内聚破坏及其组合。涂层附着损伤度是涂层损伤的主要因素,且随加载次数持续增大,当加载次数较大时内聚损伤贡献突出。试验涂装体系在22万次应力循环后附着损伤度最大为0.34,内聚损伤度最大为0.27,总损伤度达0.61,属于严重损伤。提出的损伤度模型及破坏分级方法与试验规律吻合良好,可应用于公路钢桥涂装层受动荷载作用下的寿命预测。     

Low-cycle fatigue assessment of offshore mooring chains under service loading

The integrity of mooring chains is essential to the safety of a range of offshore platforms. However, mooring line failures are occurring earlier than their design lives, with a high number of these failures occurring due to fatigue. Early in the fatigue life of the component fatigue initiation processes occur, where the fatigue hotspot is sensitive to the mean load and there is plastic strain accumulation from the multiaxial stress-strain responses of the material, leading to cyclic plastic damage accumulation. The traditional SN approach suggested by mooring standards does not consider these effects, and it is proposed that this lack of consideration under low-cycle fatigue conditions is the reason for the current non-conservative fatigue assessments of mooring chains. This paper aims to develop a fatigue approach based on a critical plane multiaxial fatigue criterion for mooring chains that can consider the damage-induced by the cyclic plasticity and the mean load effect, to investigate the importance of incorporating low-cycle fatigue into the mooring chain life prediction. To develop the critical plane approach, the multiaxial stress-strain states are extracted for the critical plane at the fatigue hotspot from a finite element model of a mooring chain. This is then correlated with a fatigue life prediction provided by conventional fatigue design data. It uses a simulation of an FPSO as a case study to demonstrate the importance of low cycle fatigue, which shows that the mean load effect is significant in reducing the fatigue life for mooring chain applications, while the effect of fatigue damage-induced cyclic plasticity is limited. The fatigue damage accumulation predicted by the critical plane approach is significantly higher than that of the traditional SN approach and should be accounted for in mooring line design.     

气垫船导管组合结构设计初探

随着气垫船向大型化发展,作为气垫船结构设计重要组成部分的导管组合结构设计越来越受到重视。文中结合国内已有的典型大中小型导管组合结构的设计参数,从导管组合结构的材料、结构型式以及传力方式等方面进行分析,总结其设计特点,并结合相关规范要求,对导管组合结构设计载荷进行分析。     

重载交通对公路路面使用寿命的影响

目前,车辆超载超限运输现象相当普遍,对公路的破坏相当严重,主要表现为大大降低了道路的服务水平、缩短了道路的使用寿命。从标准轴载的当量作用次数入手,通过对公路车辆超载问题的研究,可知超载是引起路面使用寿命缩短的主要原因。     

Simplified analysis for estimation of the behavior of a submerged floating tunnel in waves and experimental verification

To achieve rational design in waves for a submerged floating tunnel which has emerged as a new offshore transportation infrastructure, it's necessary to understand its hydrodynamic behavior. For simple but accurate estimation of hydrodynamic forces, a theoretical method is proposed and the tests with physical models in a wave flume were carried out for verification. Morison's equation was used to estimate wave loads composed of inertia force and drag force. Forces calculated by applying the linear wave theory to Morison's equation coincided well with those measured by the tests. The test results showed that mooring systems played a significant role in the movement of the submerged floating tunnel in waves. A pendulum model could be used to describe the motion of the submerged floating tunnel with a single vertical mooring. Based on the verified relations, a simple slack condition which causes the submerged floating tunnel to be unstable was also proposed. The simplified approach proposed by this study proved to be useful in designing the submerged floating tunnel in the initial stage.     

Dynamic airspace sectorisation for flight-centric operations

Today’s air traffic operations follow the paradigm of ‘flow follows structure’, which already limits the operational efficiency and punctuality of current air traffic movements. Therefore, we introduce the dynamic airspace sectorisation and consequently change this paradigm to the more appropriate approach of ‘structure follows flow’. The dynamic airspace sectorisation allows an efficient allocation of scarce resources considering operational, economic and ecological constraints in both nominal and variable air traffic conditions. Our approach clusters traffic patterns and uses evolutionary algorithms for optimisation of the airspace, focusing on high capacity utilisation through flexible use of airspace, appropriate distribution of task load for air traffic controllers and fast adaptation to changed operational constraints. We thereby offer a solution for handling non-convex airspace boundaries and provide a proof of concept using current operational airspace structures and enabling a flight-centric air traffic management. We are confident that our developed dynamic airspace sectorisation significantly contributes to the challenges of future airspace by providing appropriate structures for future 4D aircraft trajectories taking into account various operational aspects of air traffic such as temporally restricted areas, limited capacities, zones of convective weather or urban air mobility. Dynamic sectorisation is a key enabling technology in the achievement of the ambitious goals of Single European Sky and Flightpath 2050 through a reduction in coordination efforts, efficient resource allocation, reduced aircraft emissions, fewer detours, and minimisation of air traffic delays.     

新型防爆地震仪在瓦斯隧道超前地质预报中的应用

为提高瓦斯隧道地震波反射法超前地质预报现场作业的安全性及可操作性，介绍一种新型防爆地震仪的主机结构、主板设计、本安电源及远程控制等核心技术，同时介绍检波器气囊耦合技术；最后采用36道防爆地震仪和高精度三分量地震检波器气囊耦合装置，在重庆渝北至四川广安高速公路华蓥山隧道进口右线K24+314掌子面处进行超前探测试验，其采集的地震记录质量高，气囊耦合方式现场操作方便快捷。经过与传统的国外TSP仪器及钢管锚固剂耦合方式对比分析，充分说明采用国内的矿用防爆地震仪及其配套研制的检波器气囊耦合装置完全适用于各类瓦斯隧道地震波反射法超前地质预报工作，且能使地震波反射法实现本质安全。     

高速公路路堤基底承载力计算方法分析

基于高速公路路基基底应力的三种计算方法，即比例荷载法、等效荷载法、三维数值分析软件FLAC3D，对高速公路路堤基底承载边进行计算。通过计算结果的对比分析，归纳了路基基底应力随着路堤高度和基底软土厚度变化的分布规律，并提出了路基基底应力的计算公式，可作为路基基底承载力或软基清淤的量化评定，避免人为地判断地基处理合格性。