Experimental Study On Permeability Characteristics Of Cemented Sand And Gravel

Cemented sand and gravel has been widely used in water conservancy projects in recent years.From the initial use in cemented sand and gravel cofferdams to later development to be widely used in cemented sand and gravel dams,the application range and potential of cemented sand and gravel materials have been greatly increased.Development,with the rapid development of cemented sand-gravel dams,theoretical research on the properties of cemented sand and gravel materials has become more and more important.In recent years,many experts and scholars have carried out comprehensive research on the physical and mechanical properties of cemented sand and gravel.Exploration,lack of systematic research on penetration.Combining the mix ratio to study the permeability and structural characteristics of cemented sand and gravel,and summarize the rules between them,it is necessary to predict the permeability parameters of actual engineering,evaluate the safety of seepage,and expand the practical use of cemented sand and gravel in engineering.It has very important theoretical significance and practical value.For the permeability of cemented sand and gravel,the permeability coefficient is an important parameter,because the permeability coefficient is only related to the nature of the material’s skeleton,and the skeleton properties of the cemented sand and gravel material intuitively depend on the pore distribution,and it depends on the source.To the material mix ratio.In view of the close correlation between the permeability coefficient of the cemented sand and gravel material and the pore distribution and mix ratio,this paper will systematically study the three together.The specific content is as follows:（1）Through the indoor penetration test of cemented sand and gravel under different mixing ratios,the influence of cement dosage,fly ash dosage,water-binder ratio,sand ratio and age on the permeability coefficient is analyzed,and the glue The average value of the optimal water-binder ratio of the condensed sand and gravel in the selected mix ratio is 1.05,and the average value of the optimal sand ratio is 0.228.The influence degree of the permeability coefficient of each factor is sorted by the analysis of variance method,and it is concluded that cement>sand ratio>Water-binder ratio>Fly ash.（2）The NMR test was carried out on the cemented sand and gravel test blocks,and the corresponding porosity and T₂spectrum curves of the test blocks with different mix ratios were obtained,and the changes of porosity and pore size distribution under different mix ratios were analyzed;The pore distribution characteristics of cemented sand and gravel were studied on the surface level.（3）The introduction of fractal theory,combined with the T₂spectrum curve to describe the complexity of the internal pores of the cemented sand and gravel and expressed it with fractal dimensions,combined with the permeability coefficient and porosity obtained from the test,and the method of regression analysis The correlation analysis between internal pore distribution characteristics and permeability coefficient shows that there is a pairwise linear correlation between permeability coefficient,porosity and fractal dimension.