Triaxial Test Study On Wet Deformation Of Coarse Grain

Earth-rock dam has become one of the most popular dam types at home and abroad due to its good terrain adaptability and economy.With the development of dam construction technology for earth-rock dams,the height of dam construction is constantly being refreshed.The increase of dam height enhances the regulation and control capability of the reservoir,but the lower safety margin of materials will also bring certain potential safety hazards.Earth-rock dams will crack due to wetting deformation during initial impoundment and rainfall.This is because the coarse grains used as dam materials are soaked by water,which leads to the reduction of particle strength,particle breakage,sliding,structural adjustment,etc.,and further causes dam settlement deformation and even dam cracking.Wet deformation and crushing properties of coarse aggregates are especially important for predicting dam deformation.In this paper,an improved large-scale triaxial test system is used to carry out wetting tests on limestone in Dalian,and further study the wetting deformation of coarse aggregate in rockfill dam.Through the "single-wire method" test,the stress-strain relationship and axial variation relationship of wetting samples under different confining pressures and different stress levels are studied,and the wetting deformation properties of coarse grains are further studied.Through screening the samples before and after wetting test,the particle size distribution is determined,and the particle breakage under different wetting stress conditions is studied.Through indoor wetting test research on coarse particles,the basis is provided for future engineering practice.Analysis of the wetting test results of coarse grains shows that:(1)there is a linear relationship between the specimen volume strain and the axial strain during the wetting test;(2)there is a linear relationship between the wetting volume strain and the confining pressure;and(3)the wetting volume strain firstly increases and then decreases with the increase of the stress level,and there is a maximum wetting volume change,and the stress level corresponding to the maximum wetting volume change is the critical stress level.(4)Particle breakage during humidification is related to confining pressure and stress level.This paper,through the research on indoor wetting test of limestone in Dalian,the wetting test method is improved,the relationship between wetting volume strain and confining pressure and stress level is analyzed,the calculation formula of wetting volume strain based on critical stress level is proposed,and the critical stress level is studied.The law between particle breakage and confining pressure and stress level is analyzed.