Study On Resource Utilization Technology And Application Of Ecological Revetment Block Prepared From Dongting Lake Sludge

In recent ten years,the harm caused by sediment deposition in Dongting Lake has become more and more prominent.The lake area dredging treatment has become a major strategic measure for ecological water control in Hunan.At the same time,with the proposal of strategic policies such as "beautiful Dongting" and "harmonious Dongting",it is urgent to build ecological embankment and Wetland Demonstration Area.Therefore,in view of the shortcomings of the existing traditional sludge disposal methods,such as resource waste and secondary pollution,a new resource reuse method of preparing ecological revetment blocks with silted sediment is proposed.The specific research ideas are as follows:firstly,combined with the hydrogeology and engineering geology of Dongting Lake area,the implementation process of preparing ecological revetment blocks from Dongting lake sludge is proposed,and the ecological revetment blocks are selected and designed and suitable vegetation is screened;Secondly,the sinterability of Dongting lake sludge is evaluated,and a new method to determine the optimal sintering conditions of sludge with different properties is proposed;Finally,the research results are tested on typical embankments in Dongting Lake area.The main research contents and conclusions of this paper are as follows:(1)This paper compares and analyzes the recycling methods of Dongting lake sludge from the aspects of economy,environmental protection and convenience,puts forward the recycling path of preparing ecological revetment blocks from Dongting lake sludge,and designs its preparation process,appearance,suitable materials and vegetation.The key steps in the process of preparing ecological revetment blocks from sludge include sludge sampling and analysis,sinterability evaluation,lightweight aggregate sintering and ecological revetment block pouring;According to the relevant embankment specifications and combined with the hydrological and geological characteristics of Dongting Lake area,it is determined that the ecological revetment block is a hexagon with a side length of 10 cm,and a cylindrical planting area with an inner diameter of 10 cm is set in the middle.(2)Based on the orthogonal test results of sludge sintering conditions optimization,a rapid method for determining the optimal sintering conditions of sludge with different properties in water area with multi-objective ideal points is proposed.Taking four sintering conditions(preheating time,preheating temperature,sintering time and sintering temperature)as independent variables and the five most important properties of lightweight aggregate as dependent variables,a sintering condition optimization model based on multi-objective ideal point method is constructed,and the feasibility of the model is demonstrated by experiments.The results show that under the conditions of preheating time of 20 min,preheating temperature of 410℃,sintering time of 5 min and sintering temperature of 1112 ℃,the sintered lightweight aggregate has excellent properties,with porosity of 23.31%,expansion rate of-5.75%,bulk density of 1.28 g/cm3,compressive strength of 20.35 MPa and 1H water absorption of 14.33%.(3)Based on the orthogonal test results of the mix proportion of ecological revetment blocks,the optimal mix proportion of ecological revetment blocks is calculated,and the steps and processes of preparing ecological revetment blocks are determined.The three factor and three-level orthogonal test of water cement ratio,particle size of lightweight aggregate and target void ratio is established.After optimizing and analyzing the test results,the optimal mix ratio of ecological revetment block made of lightweight aggregate sintered from Dongting lake sludge is obtained:the water cement ratio is 0.27,the particle size of lightweight aggregate is 15 mm and the target void ratio is 25%;At the same time,combined with the previous research,the preparation process of ecological revetment block is determined.(4)The research results of this paper are applied to the typical embankment in Dongting Lake area to carry out demonstration research,and the process flow of preparing and laying ecological revetment blocks is established.At the same time,the feasibility of the application of ecological revetment blocks is verified by evaluating the stability and comprehensive effect of the embankment in the demonstration section.Field application shows that compared with ordinary concrete blocks,using ecological revetment blocks for revetment can save about 40%of the cost;It can improve the ecological environment of the city and both sides of the embankment and improve water resources.At the same time,the stability of the embankment is analyzed in combination with the field survey data.Using ecological revetment blocks for revetment can improve the stability of the embankment by 5%,and the revetment effect is good.The research results will provide a theoretical basis for scientifically guiding the preparation of ecological revetment blocks from Dongting lake sludge,and can also provide reference and guidance for the resource utilization of sludge in domestic and foreign waters,which has a wide application prospect.