Research On Anti-seepage Performance Of Grouting Curtain With Expansion Composite Slurry

The seepage problem of earth rock dam is closely related to the investment and safety of water conservancy project.Grouting can properly deal with seepage problems of earth and rockfill dams.The effect of the grouting is also obvious.In hydraulic engineering,cement and chemical pulp are the main impervious grouting materials.Cement slurry has the following advantages,such as,low cost and high strength of stone body.But its shortcomings are also obvious,such as,the problem of poor fluidity,low stone rate and so on.So the effect of grouting is not optimistic.This paper combines the design requirements of impervious grouting.The author develops the expanded composite grouting material through the indoor mix proportion test.Numerical simulation is also used to study the impervious performance of grouting curtain.The main content of this paper includes 4 parts:1)The mechanism of impervious and water plugging of expanded composite slurry is analyzed.The performance characteristics of the ideal impermeable grouting material is understood.The appropriate composition of the composite slurry is selected.This paper studies the performance of cement as the main material,mixed with different proportions of bentonite,fly ash and expansive agent in a certain proportion of water and solid ratio.2)The most suitable mix proportion is selected through physical and mechanical properties,free expansion rate and impermeability test of slurry and stone body.The experimental results show that:The comprehensive performance of expanded composite grouts best with 0.8 water and solid ratio,25%bentonite,30%fly ash and 10%expansive agent.The viscosity of the slurry is 37.14 m Pa·s,the density is 1460 kg/m³,and the 28 day compressive strength of the stone body is 4.32MPa,the free expansion value is0.176mm,the free expansion rate is 0.0704%,and the permeability coefficient is 1.206×10^-8cm/s.It can be concluded that this composite slurry has many advantages over traditional cement slurry through analysis.First of all,the composite slurry has certain expansion property.Later expansion force can counteract the later shrinkage of cement slurry to enhance the effect of seepage prevention;Secondly,the composite slurry mixed with bentonite has good stability.It can reduce the size segregation and bleeding;Moreover,the addition of fly ash to a suitable proportion of expansive agent can improve the fluidity of slurry.It is beneficial for good grouting effect.Finally,it can reduce project cost and save cost with some fly ash instead of cement.3)Numerical simulation of anti-seepage performance of expanded composite grouting curtain is carried out through the construction of the grouting stratum model,using CFD to calculate the theory of fluid mechanics.The dynamic changes and correlations of soil parameters in grouting process are considered during the simulation.Considering the influence of multiple factors on the expansion of slurry size in the hole,we analyze the permeability and permeability coefficient of expanded composite slurry curtain consolidation body（impervious body）.The diffusion range of the expansive slurry is simulated.The seepage control effect of consolidation body（impervious body）after grouting is discussed.4)The expansion compound slurry is injected into the soil.After the slurry is condensed,hardened,and expanded,it is better to wrap around the soil.Thus the consolidation body（anti-seepage body）is formed.The permeability and diffusion range of the stone body formed by expanded slurry and soil are studied.From the analysis and extraction of soil parameters,the permeability test after grouting is verified.The test results are in accordance with the simulation.The research shows that the hydraulic properties of cement slurry are improved by adding expansive agent,fly ash and bentonite in the cement slurry.The permeability coefficient of the consolidation body（anti-seepage body）is reduced greatly after the grouting.The results can be applied to the grouting curtain to achieve better seepage control effect.