疏浚吹填工程推行项目经理责任承包制管理模式的探讨

阐述了传统管理模式的生存条件及其弊端,对疏浚吹填工程推行项目经理责任承包制管理模式进行了探讨.     

Effect of Channel Changes in the St. Clair River During the Present Century

Periodic man-made changes in the outlet of Lake Huron through the St. Clair River date back to the middle of the last century. These artificial channel changes have been well documented during the present century. They consist of dredging for commercial gravel removal in the upper river during 1908–25 and uncompensated navigation improvements for the 7.6-m (25-ft) and 8.2-m (27-ft) projects completed in 1933 and 1962, respectively. The total effect of these changes on the levels of Lakes Michigan and Huron (hydraulically one lake) and on the upper St. Clair River profile was determined with dynamic flow models. The ultimate effect of the above dredging was a permanent lowering of the Lake Michigan-Huron levels 0.27 m (0.89 ft), which represents a tremendous loss of freshwater resource [32 km³ (7.7 mi³)].     

挖沙船的变频节能改造分析

挖沙船上主电机在采用变频调速以前,多用星三角起动或自耦减压起动方式。这种启动方式起动电流较大,导致所选用的柴油发电机的容量过大。采用变频调速以后,可以减小电动机的起动电流,降低柴油发电机的容量,减少前期投资,给企业带来可观的经济效益。     

Environmental studies on impacts of dredging

The coastal zone acts as a major interface between the ocean and continents. Harbours located in this zone face grave problems from sedimentation, which is a global issue for most of the harbours of the world. Dredging which counter acts sedimentation, brings about innumerable environmental impacts — both positive and negative. As a case study, this paper reports the impacts of dredging conducted at Cochin harbour which is the second largest port along the west coast of India; this port is a nodal center in trade and commerce connecting south east Asia to European sector. The harbour operation mainly depends on maintenance form of dredging bringing about impacts which have both direct and indirect effects in the long term. The important parameters selected for this study are salinity, current, extinction coefficient, turbidity, nutrients, chlorophyll and bottom fauna. An assessment is made on both positive and negative impacts which indicate rise in turbidity, changes in nutrient content and biota. The current practice on dredging is conducive to harbour operations, regulating the material made available to the near shore areas and highlights the possible venues for utilization of spoil for reclamation of land and wetland development. A flow chart identifies the areas vulnerable to impacts arising out of dredging and its consequential environmental issues.     

牵引式管道清淤机器人无线通讯系统设计

简述了一种新型排水管道清淤机器人无线通信系统的结构,提出了一种基于ZigBee技术的无线通信策略。针对排水管道管壁对信号的屏蔽效果,通信系统采用星型网络拓扑结构,在井口设置一个路由器节点,转发地面控制器与清淤机器人的指令数据,确保信号稳定传输。设计了地面控制台的电路原理图;制定了系统控制指令传输协议。实验测试结果表明,系统数据传输稳定,满足工作环境的需求。     

Healthy Port Futures: Rethinking Sediments for Rivermouth Landscapes

Throughout the Great Lakes, port cities are often located on the rivermouth and where rivermouths once sorted, shaped, and moved the riverine sediment into the lake. Their current use as industrial navigation channels requires cyclical mechanical maintenance dredging. Past sediment management practices have either placed the riverine sediment nearshore in confined disposal facilities (CDFs) or out in deeper open water. Both practices remove the sediment from the nearshore system, preventing its potential use in coastal protection, habitat creation, wave attenuation, and sediment nourishment. However, novel rivermouth wetlands can draw from both strategies of containment (as in a CDF) and cost-efficiency of non-containment (open lake disposal) to allow for the processing and use of sediment. This article will describe one such attempt, conducted by the Great Lakes Protection Fund-supported Healthy Port Futures project. Through a collaborative design-research process, Healthy Port Futures used a range of tools to generate, speculate, model, visualize, and test wetland forms under a range of social, ecological, and hydrological conditions. This project, understood colloquially as “the Crescent,” proposed a semi-circular, partially open-cell wetland design as a response to the complexity of rivermouth conditions. Throughout this design-research process, the project sought to acknowledge uncertainty, assess risk, and explore a range of outcomes in order to redefine the public expectations around wetland creation and restoration, and reimagine innovation along the Great Lakes coast.     

Stabilized Dredged Material. I: Parametric Study

This study presents the results of a treatability study for dredged material (DM) stabilization using 20 combinations of pozzolanic agents (lime, cement kiln dust, high alkali and slag cements, and fly ash). The DM consisted of CH/OH soil excavated from the U.S. Army Corps of Engineers Craney Island confined disposal facility in Hampton Roads, Virginia, having an in situ moisture content of approximately 130% and void ratio of 3.35. Mix designs were prepared for each stabilized DM (SDM) blend using a 3-day mellowing period for the SDM blends to become compactable. Typical maximum dry unit weights were on the order of 11.9–12.9?kN/m3 (76–82?lb/ft3), for total dry pozzolan doses to wet DM between 5 and 95%, the upper dosing limit being unconstrained for potential use of the SDM blends as fill. Unconfined compression strength (UCS) testing of the SDM blends using DM with an initial MC of 132.5% was completed in accordance with ASTM D1632 and ASTM D1633 for curing times of 7, 28, and 180 days. The 28-day cured specimens had UCS values up to 800 kPa (115 psi). Leaching analyses of the various SDM blends for Resource Conservation and Recovery Act metals using toxicity characteristic leaching procedure and deionized water solutions for extended durations and contact times illustrated that the SDM blends were nonhazardous and virtually identical to the raw DM. Overall, the use of industrial by-products in SDM blends suggests that it may be possible to undertake large-scale fill construction that is sustainable, cost-effective, and environmentally protective of human health and the environment.     

Stabilized Dredged Material. III: Mineralogical Perspective

The prior two papers in this series reported on the geoenvironmental and geomechanical properties of 20 stabilized dredged material (SDM) blends using dredged material (DM) from the U.S. Army Corps of Engineers Craney Island confined disposal facility. The pozzolans included lime, cement kiln dust (CKD), class F fly ash, and two cements (portland and slag cement). This paper reports on the mineralogical evolution of the SDM blends over a 6-month curing period using techniques new to mainstream geotechnical engineering: X-ray diffraction (XRD) with Rietveld quantification analysis which allows direct quantitative mineralogical comparisons between soil samples. Despite being classified as a high plasticity clay-organic clay (CH/OH soil), XRD showed that the DM contained no montmorillonite, illite or kaolinite, and was thus mineralogically unreactive. The quartz, feldspar, and mica contents were numerically tracked and were shown to remain stable 6 months after blending. The chlorite (in DM) content decreased over time and with the fly ash served as the sources of soluble silica and alumina for pozzolanic reactions especially in the lime-based SDM blends. Lime in the lime-based blends persisted in significant quantities (3%) as unreacted portlandite [Ca(OH)2] even at 6 months curing, indicating that the solubility of silica in the DM was the limiting factor for strength development. New (ettringite and hydrocalumite) mineral formation was quantified. CKD provided high early strength (7 and 28 days) when used in combination with small amounts of lime that provided prolonged pH buffering; CKD alone or in combination with fly ash did not maintain elevated pH (>10.8) over 6 months. Overall, the unconfined compressive strength, pH, and mineralogy results at 6 months were substantially different compared to the standard curing time of 28 days, confirming similar findings of previous long-term stabilization-solidification studies.     

挖泥船泥浆管道输送工况点的在线动态优化方法

分析挖泥船泥浆管道输送系统的构成、特性以及边界约束条件。提出一种以比能耗为优化目标的泥浆管道输送工况点在线动态优化方法。既克服以产量最大化为优化目标时能耗过高、效率偏低的弊病,又很好地解决现有离线静态优化方法不适合应用到泥浆管道输送过程中进行工况点连续优化的问题。提出的工况点在线优化方法以实时检测的系统过程参数为基础,利用模糊决策方法进行工况点优化,不依赖于对系统设备特性的准确描述,特别适合于疏浚施工过程中土质和系统特性不断发生变化的场合应用。在浙江临海疏浚施工现场对所提出的方法和传统的手动疏浚作业方法进行对比试验,试验结果证明了该优化方法的有效性,不但提高了疏浚产量,而且减少了泥浆流速和浓度的波动,降低比能耗,提高泥浆管道输送系统的效率。     

多功能射流挖泥船研究

阐述一种新研制挖泥船的三个主要功能。提出了该系统的设计理论及计算方法,并在菲律宾共和国的宾加水库进行了现场试验,试验结果与设计计算数值基本吻合。该设计理论及方法可用于工程设计。