高矿化度环境下黏性土对膨润土-砂土复合防渗层抗渗性的影响研究

Research on Influence of Clayed Soil on Impermeability of Bentonite-sand Composite Layers in High Mineralization Environment

以宁夏广泛分布的砂土为研究对象,以黏性土掺量c、盐浓度d、盐的复合比r、膨润土掺量p为因素,渗透系数为考察参数,设计L9(34)正交实验方案和单因素实验方案,实验研究了盐对膨润土-黏性土-砂土复合防渗层抗渗性的影响,揭示了黏性土掺量c、盐浓度d、盐的复合比r、膨润土掺量p等因素对膨润土-黏性土-砂土复合防渗层抗渗性的作用规律和作用机理,为砂土基防渗层设计、施工提供理论依据。实验研究表明:在盐溶液环境中,膨润土的作用效应降低,黏性土的作用效应显著增强,但膨润土仍然是影响砂土基防渗层渗透性最主要的因素;土样的渗透系数随着盐溶液复合比的增大,呈现出先减小,后略微增大的趋势;黏性土使盐对砂土基防渗层的抗渗性影响显著降低,尤其是在高矿化度环境下,作用效应更为显著。

Choosing the sand widely distributed in Ningxia area as research object,the bentonite content,clayed soil content,salt concentration and salts combined ratio as factors,and the permeability coefficient as investigation parameters,the L9（34） orthogonal test plan is designed to study the influence of salt on the impermeability of bentonite-clay-sand composite layer.The rule and mechanism of impermeability is revealed.A theory basis is provided for design and construction of saliferous sand impervious layer.The effect of bentonite is reduced while the effect of clayed soil is increased markedly in salt solution,but bentonite is still the main factor in four vetting factors.The permeability coefficient of soil first decreases,then increases with the salts combined ratio increasing.The clayed soil makes the influence of salt on the impermeability of sandy composite layers become lower,especialy in high mineralization environment.