Environmental Dredging And Its Control Research

Abstract: When the polluted water body has been controlled effectively in the out source, it is necessary to control the inner source of river and lake water body by the environmental dredging engineering measurement. The purpose of the environmental dredging is to remove the polluted bottom mud in the river and lake. The significant advantage of the environment dredging different to conventional dredging is to take the creating condition for the restoration and regeneration of the hydrophilic biogeocenose into consideration. Carrying out the environmental dredging according to water environment treatment and ecologic restoration planning, and creating the condition that makes for the ecologic recovering by means of environmental dredging.The excavating control is the first step among the four steps of excavating, lift-up, horizontal transportation and treatment, the research shall be mainly aimed at two respects: improvement of excavation accuracy and prevent the suspension material from diffusing. Since the start of development in environmental dredging domestically is rather later, there is certain disparity in the study and development of these two respects with the international level. From the point of view of economy and practicality analysis, processing the technical modification for the existing middle and small scaled routine environmental dredging equipment in order to meet with the requirement of the environmental dredging is national current major developing heading. In this text the two respects of improving the excavation accuracy and prevent the suspension material from diffusion will be specially studied based on the cutter suction dredger as the mother ship which used commonly in our nation.The vertical positioning of the dredge can be done by water conversion calculation positioning or use the method of RTK-GPS positioning. Even the excavating accuracy can be meet with the requirement under applicable condition by the water conversion calculation positioning, but the excavation accuracy will be influenced in case of narrow, closed or storm water area. The application of RTK-GPS positioning method shall not only realize the same accuracy as the water conversion calculation, but also get over application limitation from the water conversion calculation positioning with the system applicability enhanced. The excavating accuracy alsodepends on the dredging equipment, construction process parameter (such as thetraverse movement and speed of the reamer, the flow rate of the slurry pump), soiletc. But the excavating accuracy will be reach up to the target of≤10cm with thestudied control system in this text.The range of the diffusion quantity depends on the soil type, process parameter (theexcavating head rotation speed, grain depth of the cut, the flowrate of the slurrypump etc.), excavating head stance and the location of suction inlet etc. The studyis carried out in the aspects of sediment settlement characteristic, cutter headguard, diffusion mechanism, traverse shift direction and suction inlet location etc.The target of diffusion range≤5m with fine grain remove rate >95% can be realizedby adding the cutter head guard, control the process parameter, set up double suctioninlet.Research Achievements:1．Zhang Qingbo, Xiao Yong, Dai Chengli , Zhang Jingming, Shanghai Waigaoqiao Port Area Land Formation and Foundation Treatment. Port and Waterway Engineering, 2002 issued 10, 45～472．Zhang Qingbo, Research on Foundation Base Rehabilitation Scheme of Yunnan Erhai Sea Lakefront Ecological Restoration Project, Port and Waterway Engineering, 2002 issued 10, 50-523．Zhang Qingbo, Lu Xinhua, Zhou Hai, Environmental Dredging and Ecological Restoration, 2004, CHINA DREDGING ASSOCIATION Technical Exchange Paper Corpus.4．Zhang Qingbo, Land Formation Engineering Quality Control for Shanghai International Shipping Center Yangshan Deepwater Port First Phase Project , China Communication Press, Paper Corpus of First-Phase Yangsan Deepwater Port of Shanghai International Shipping Center, 306-3125．Zhang Qingbo, Lu Xinhua, Zhou Hai, Ecological Restoration Studies on Natural Wetland, the Proceeding of Eighteenth World Dredging Conference of the World Dredging Association CommitteeIntroduction of the Author: Zhang Qingbo, male, birth on 1972, graduated from Hehai University in the year 1994, major in port and sea-route engineering and took a bachelor' s degree in engineering.