Study On Ecological Anti-seepage Technology For Artificial Lakes

In order to create a system of urban landscapes,artificial lakes of various sizes have been built.Its ecosystem generally has poor self-regulation ability and needs special ecological environment design.The anti-seepage treatment design is its key point.Conventional anti-seepage treatments include structural types such as curtains,sill walls,hard rafts,paving and geomembrane,but there are deficiencies in ecological requirements.Therefore,this paper proposes an ecological anti-seepage technology suitable for artificial lakes.Microorganisms represented by Sporosarcina pasteurii(SPP)can deposit a large amount of calcium carbonate by metabolism,block pores and reduce leakage.Microorganisms themselves are derived from nature,and microbial grouting is more environmentally friendly than traditional anti-seepage techniques.Microbial metabolic deposition of calcium carbonate(MICP)has made great progress as an ecological geotechnical anti-seepage method.Through comparison,the SPP strain suitable for laboratory culture was selected and successfully cultured and preserved in the laboratory.The optimal conditions for cultivating SPP were obtained by strain culture experiment:expansion factor was 10 times and constant temperature was 30 ?.The pH of the medium was maintained at 6.2.The cultured strain and the culture solution were perfused with a 50 ml sand column through a grouting pump to carry out a small-scale sand column test.As the concentration of the bacterial liquid increased,the activity of the bacterial liquid was significantly improved.The concentration of the bacteria solution was 5?10,the concentration of Ca2+source was 1mol/L,and the concentration of urea was 2mol/L.The maximum compressive strength of the sand column was 22.06MPa,and the minimum value of the permeability coefficient was 2.12×10-5cm/s.The sand column that is infused more than 2 times can be cemented into a complete sand column.When the saturation is 0,the curing effect is better.The sample at room temperature or immersion curing is more resistant to compressive strength and penetration than the sample dried and cured.Low,the maximum compressive strength is 2.87 MPa,and the minimum permeability coefficient is 1.54X10-4 cm/s.The soil samples with different properties were selected for the one-dimensional and two-dimensional diffusion simulation tests of the microbial slurry.Under the maximum grouting pressure of 0.2 MPa,the diffusion distance of the sand was 1.8 m or more,and the diffusion distance of the loess was 60 cm.The permeability coefficient of the soil samples is less than 1.0×10-5 cm/s.Taking the second phase project of Tuancheng Lake as an example,the ecological anti?seepage design with microbial grouting as the core was carried out,and three-dimensional seepage analysis was carried out.The results show that after the ecological anti-seepage,the total leakage of Tuancheng Lake is reduced to 1%before treatment,and the maximum hydraulic gradient is less than 3,which meets the requirements of anti-seepage.At the same time,the daily leakage can reach 1439m3.Meet the ecological storage requirements of the surrounding ecological environment.The water ecological environment impact assessment system was established by:fuzzy analytic hierarchy process to evaluate the ecological environment impact of the ecological anti-seepage system.Combined with the weights of various indicators,the comprehensive evaluation scores of different anti-seepage methods on water ecological environment were calculated.The composite geomembrane,concrete anti-seepage,clay anti-seepage and ecological anti-seepage scores were 58.0,57.5,65.8 and 72.7,respectively.The impact of the system on the aquatic ecosystem is less than other methods of seepage prevention.The above research proves that the ecological anti-seepage technology based on microbial grouting can be used for the anti-seepage of the bank slope of artificial lakes.On the basis of meeting the anti-seepage requirements,the anti-seepage measures are minimized to the ecological environment.Influence to achieve a balance between anti-seepage and ecological protection.