Research On Optimal Design Of Mix Ratio Of Hydraulic Asphalt Concrete Considering Fine Aggregate Ratio

Hydraulic asphalt concrete is widely used in anti-seepage parts of hydraulic engineering because of its excellent anti-seepage and adaptability to deformation.At present,most of the water conservancy projects under construction in my country are located in the western region with high altitude,high seismic intensity,and alpine climate.In iew of the complex dam construction conditions in the western region,the hydraulic asphalt concrete mix design theory based on the semi-empirical single-factor method will face difficulties.The small pressure has the disadvantages of subjectivity and difficulty in considering the interaction between components.At the same time,it is difficult to obtain a th eoretical m ix ratio scheme that takes into account various needs,so it cannot meet the efficient and accurate m ix ratio design requirements of the current asphalt concrete anti-seepage engineering.T herefore,there is a realistic demand for engineering construction to carry out research on the material mix ratio design of the anti-seepage body of asphalt concrete core wall dam.In this paper,taking the impermeable material of the asphalt concrete core wall dam core wall as the research object,and explores the research on the optimal design of hydraulic asphalt concrete mix ratio considering the fine aggregate ratio through indoor experiments and multiobjective particle swarm optimization algorithm(MOPSO).The main research content and results are as follows:(1)Due to the different composition effects of coarse and fine aggregates in asphalt mixture,the mathematical models of coarse aggregate and fine aggregate gradation were studied respectively,and a new aggregate gradation curve was obtained through synthetic gradation design,and the new gradation was verified by comparative experiments design pros and cons.The results show that the process of step-by-step filling of coarse aggregate follows the cyclical process of accidental interference-inevitable interference-new round of filling.There is a critical value in the amount of secondary aggregate added.At this time,the aggregate and the parent body are in equilibrium,but the optimal skeleton does not correspond to the maximum density of the aggregate.Compared with Ding Purong’s formula,the new grading curve has more large-size aggregates(9.5-19mm),and less medium-sized aggregates(2.36-9.5mm).In the range of fine aggregate ratio of 30-60%,the porosity and flow value indexes of the test group are slightly better than those of the control group,and the stability index is increased by 11.3%on average compared with the control group.The design of the new aggregate gradation curve provides a new way to seek hydraulic asphalt concrete with better performance.(2)Based on the response surface method,the mix ratio design research is carried out,and the prediction model of the performance index related to the mix ratio parameters is established.Combined with the technical requirements of the performance index,the mix ratio space is constructed,and the mix ratio test data is graphed.In addition,the redesign of aggregate gradation and the introduction of fine aggregate ratio parameters reflect the idea of gradually refining the design of each component of the mix ratio,and it is also an improvement on the design method of the mix ratio.The mix ratio space can directly provide mix ratio parameters for small and medium-sized asphalt concrete core dams,and narrow the range of mix ratio parameters for mix ratio tests in large-scale projects.(3)Based on MOPSO,carbon emissions and economic costs are used as the objective function to optimize the mix ratio.After optimization,the linear weighted sum method is used to screen the optimal mix ratio in different directions,which avoids the blindness of single-objective and single-parameter optimization methods.Among the three parameters of the mix ratio,the filler concentration has the greatest impact on the carbon emission and economic cost of asphalt concrete,followed by the cement-bone ratio,and the fine aggregate ratio has the least influence.MOPSO iterative optimization,the Pareto optimal solution is obtained,which can be used for designers to choose mix ratio schemes according to different needs.