Research On Microstructural Stability Influencing Permeability Of The Clay Liner

As backfills being more and more effectively and wide-used waste handling way , trash sieving fluid pollution ground water event along with it is more and more directly endangering human's health. Once divulging occurs, it will be able to create unexpected consequence which will not be retrieved. Therefore, how to enhances guard against-infiltrating performance of the backfill become the core topic of the correlation researches. Based on this, the research of performance mechanism to reduce guards against infiltrate- ing performance is the key problem.No matter uses which liner, the clay liner is an essential part. The bentonite clay hydrated inflation is the essential reason that has against infiltrating ability. In recent years, the bentonite especially applied to the radioactivity dangerous solid waste backfills. The microscopic structure of the clay mineral decides overwhelming majority physical properties. This spot may be confirmed by comparing original and nonperturbation bentonite clay with the air seasoning, grinds bentonite clay that their water power conductivity coefficient differences obtains the confirmation. When the clay has the clay particle has the same nature and uniform continuity distribution, the clay has very good compactness. When the ambient pressure and the clay sensitive density equals, the clay guards against-infiltrating ability will be the best. When bentonite clay and water contact, the kind and concentration of ion ingredient will influence the physicochemical properties of bentonite nearly and will affect its inflation differentiation and guards against-infiltrating performance. The choice flower post crag achievement guards against infiltrates in the level the inert material, is because it distributes widely, is very easy to obtain, even in fills in buries in the field pit excavation process to be able to obtain, the price is inexpensive, and more importantly spend the post crag the use the environment tlothological change to fall the solid waste to the lowest degree, has avoided trash body and water body osmotic pressure between the environment difference, around trash body in the rock water cannot to trash body permeating.Based on the experiments,the present paper elaborated the pH and concentration of the sieving fluid influence the density and the moisture content of the clay liner, and then till to change its microsco- pic structure. From the slight place , the paper explains the reason the change of clay water conducting power, in order to propose the improvement measurement and truly achieve that backfill liner safe, economical and feasible. Meanwhile it provides the certain theory basis for weakening the chemicals influences of sieving fluid on backfill liner performance.The experiment selects granite∶montmorillonite( 70∶30)clay mixture achievement as clay backfill, and the density is1.1g/cm3. Because the average density of the clay is smaller, the penetrating fluid for the ,the salt water, the acid liquor, the lye ,the whole change scope of the average density and the moisture content distinguish not too greatly. But the whole change scope of the deionized water change much more greatly comparing with the others。It is explained that in ion in the penetrating fluid has minished the expansion power of the clay.The experiment indicating that when there is not any ambient pressure inflicted on the liner, in other words,the clay can expanding in the free expansion situation,if the adion is Na+, the bentonite layered crystal may inflate and form three layer-levels; if the adion is Ca²⁺, can only form two layer-levels. Therefore, when the bentonite clay pore water has Ca²⁺ and Na+ and the bentonite clay inflation performance comes under the suppression, the clay expanding performance weaken. The conclusion of the experiment and the classic theory of DDL accords:(1)The hydrated inflation of bentonite is the essential reason for its guard liner performance. As a result of the replacement of the negative charge, which produces the belt negative charge surface. Therefore, when the clay mineral frequently attracts the positive ion in solution, it forms the proliferation DDL. At the same time, the clay mineral surface and the crystal level adsorbs the ion and attracts the massive polar hydrone, and causes the clay mineral volume expansion, and then hydrated dispersers.(2) When there is not any ambient pressure inflicted on the liner, in other words,the clay can expanding in the free expansion situation, if the adion is Na+, the bentonite layered crystal may inflate and form three layer-levels; if the adion is Ca²⁺, can only form two layer-levels. The former inflates well comparing with the latter .This is also the reason that the calcium base bentonite clay performs worse than the sodium base bentonite clay on self-defense ability .(3)The guard-against infiltrating ability of clay is lying on the distributing characters of its microscopic structure. When the clay has the nature same clay particle and uniform continuity distribution, the clay has very good compactness. When the ambient pressure and counteracting ability equal, the guard-against infiltrating ability of the clay liner is the best.