Mechanism of Tunnel Water Inflow Caused by Bending Failure of a Waterproof Dike Based on a Circular Thin Plate Mechanical Model北大核心CSCD

Water bursts during tunnel construction endanger construction, and it is therefore necessary to reserve a waterproof dike with the required thickness to avoid water bursts and to take reinforcement of the dike and treatment of the structure liable to trigger a water burst. Using the water burst at K5+398 of the Mingyueshan tunnel of the Shanghai-Chengdu expressway as an example, and considering the type of tunnel section and the upright mudstone of the dike, the waterproof dike at the work face is simplified as a round thin plate. A formula for the calculation of a minimum safety thickness for the critical waterproof dike is deduced by analyzing the force applied on the water-proof dike, and the minimum safety thickness for the water burst section at K5+398 of the Mingyueshan tunnel is cal-culated. The numerical simulation analysis demonstrates the critical thickness of waterproof dike at K5+398 of the Mingyueshan tunnel is 1.4-1.55 m, and the calculated water inflow and water burst basically agree with the actual condition. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Analysis of the Circulation System of a Slurry Shield and the Muck Carrying Ability of a Dredging Pipe北大核心CSCD

The circulation system of a slurry shield is composed of a transportation system and a processing system.For shield construction, correct selection of the circulation system for the slurry shield is directly related to construc-tion speed. Using the Nanjing Yangtze tunnel as an example, the material balance calculation of the circulation sys-tem, sieving effect analysis, and analysis of the muck carrying ability of the dredging pipe are conducted for various strata. The practical results show that above mentioned calculations and analysis method provide a good reference for the proper selection of a slurry separation system and dredge pipe. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Assessing the impact of reduced visibility on traffic crash risk using microscopic data and surrogate safety measures

Due to the difficulty of obtaining accurate real-time visibility and vehicle based traffic data at the same time, there are only few research studies that addressed the impact of reduced visibility on traffic crash risk. This research was conducted based on a new visibility detection system by mounting visibility sensor arrays combined with adaptive learning modules to provide more accurate visibility detections. The vehicle-based detector, Wavetronix SmartSensor HD, was installed at the same place to collect traffic data. Reduced visibility due to fog were selected and analyzed by comparing them with clear cases to identify the differences based on several surrogate measures of safety under different visibility classes. Moreover, vehicles were divided into different types and the vehicles in different lanes were compared in order to identify whether the impact of reduced visibility due to fog on traffic crash risk varies depending on vehicle types and lanes. Log-Inverse Gaussian regression modeling was then applied to explore the relationship between time to collision and visibility together with other traffic parameters. Based on the accurate visibility and traffic data collected by the new visibility and traffic detection system, it was concluded that reduced visibility would significantly increase the traffic crash risk especially rear-end crashes and the impact on crash risk was different for different vehicle types and for different lanes. The results would be helpful to understand the change in traffic crash risk and crash contributing factors under fog conditions. We suggest implementing the algorithms in real-time and augmenting it with ITS measures such as VSL and DMS to reduce crash risk.     

Impact of regional population density on walking behavior

Land use can influence walking (measured by the number of steps) and so the health of people. This paper presents the result of empirical research on the impact of regional population densities (inhabitants per inhabitable area) on the number of steps (all steps, both outdoors and indoors). With data collected from almost 11,000 respondents in 148 Japanese regions, we estimate polynomial regression models, the total number of steps being the dependent variable and densities being the main independent variable. Regional population density significantly affects the number of steps after controlling for individual and household attributes. The estimated population density that maximizes the number of steps is around 11,000?persons/km². Increasing densities, up to levels of around 11,000?inhabitants/km², could increase walking and consequently the health of inhabitants. The population density elasticity of the number of steps is 0.046–0.049 in a simple log linear regression model without a peak.     

PCTC船货舱通风系统设计

PCTC船货舱通风系统的设计是整个PCTC船设计的一个重要组成部分,关系到总体、结构、舾装、轮机和电气等多个专业的设计。近几年来,PCTC船的货舱通风系统的设计也在不断的变化、改进和优化中,本人基于本所目前设计开发的6600UNITS PCTC船型,对这些年来PCTC船货舱通风系统的设计做了一个总结和分析,供相关设计人员参考。     

一种新型尾滑道式船载小艇收放系统可行性研究

作为一种新型的尾滑道式船载小艇收放系统,在回收小艇时,小艇需要以一定的航速冲上尾滑道。回收能否成功除了受制于驾驶员操作水平等主观因素,还与滑道的涉水深度、小艇与母船尾滑道的运动响应等客观条件有关。本文利用切片理论计算了小艇与母船尾滑道的运动响应,并对3级及4级海况下回收小艇的可行性进行了分析。     

新扩建以色列阿什杜德港(ASHDOD)施工关键技术

新扩建的以色列阿什杜德港项目位于地中海开敞海域,受中长周期波浪影响严重,且地质条件复杂,项目主体结构形式多样、施工难度大。通过波浪预报和地质条件分析,提出了多项创新施工技术,克服了开敞海域中长周期波浪对施工的影响,并成功引入到外海碎石桩、深水防波堤、码头桩基等关键分项工程施工中,相关施工经验可供类似项目借鉴。     

自动化散货码头装卸作业存在的问题与对策

针对目前国内已投入运营的自动化散货码头在装卸机械设备配置、功能区域划分、安全管理等方面存在的问题进行分析。提出针对性的解决对策,以进一步提高自动化散货码头的装卸作业效率并确保作业安全。对自动化散货码头的技术发展进行展望,供自动化散货码头建设或升级改造时参考和借鉴。     

港口岸线环境补偿人工沙滩工程理论与实践

依托港口岸线建设环境补偿人工沙滩工程是践行国家生态文明建设战略,实现港、城一体化发展的有益举措。针对人工沙滩建设中的理论和关键技术问题,通过自主研发,取得以下主要创新性成果:1)发展了沙、泥并存下沙滩动力地貌学基础理论;2)形成先进的数值、物理模拟技术;3)提出适用于各种复杂泥沙环境下的人工沙滩设计原则;4)研发了人工沙滩防侵蚀、防泥化的整治与养护措施。研究成果已成功应用于不同复杂泥沙环境下的实际沙滩工程中,实现了良好的经济、社会和生态环境效益,具有广阔的推广应用前景。     

散杂码头设计中节能增效措施的应用

针对码头工程中如何多方位将节能增效措施融入到设计中的问题,以长江江苏段某散杂码头及其堆场的设计为例,在工艺、结构、电气等方面采用多方位比较的方法,工艺采用装船机、取料机和皮带机变频联动系统、旋转式过渡皮带车以及三工位头部伸缩装置等措施,结构方面陆域轨道基础采用新型专利,电气方面采用风光互补路灯及岸电系统等不同的节能增效措施,使项目更经济合理、效益显著。