KCl溶液对红黏土骨架结构与抗剪强度影响的试验研究

Experimental study on the effects of KCl solution on the skeleton structure and shear strength of red clay

为深入探究KCl溶液引起红黏土力学性质发生改变的原因,对不同浓度(0.00,0.01,0.10,0.30、0.50、1.00 mol/L)KCl溶液污染后的红黏土开展了热分析试验、渗透试验和直剪试验,得出红黏土结合水失重温度区间和结合水含量、渗透性及抗剪强度的变化规律。结果表明:随着KCl溶液浓度的增加,红黏土中含量增多,由于红黏土颗粒表面负电荷紧密吸附着阳离子,引起红黏土颗粒表面Zate电位增加,使得固定层中对扩散层中排斥作用变大,扩散层厚度变厚,导致土中弱结合水的失重温度区间减小,强结合水的失重温度区间增大;红黏土孔隙溶液中随着KCl溶液浓度的增加,引起红黏土颗粒表面负电荷与KCl溶液中的K+相互作用,导致结合水含量增加,且主要改变弱结合水含量;随着红黏土中结合水含量增加,土中黏滞阻力变大,导致红黏土渗透性变弱和抗剪强度降低。本研究结果可为改良红黏土工程性质提供参考依据。

Thermal analysis test,permeability test and direct shear test of Guilin red clay contaminated with KCl solution of different concentrations(0.00,0.01,0.10,0.30,0.50,1.00 mol/L)are carried out to explore the reasons for the change of mechanical properties of Guilin red clay caused by KCl solution.The variation rules of bound water weight loss temperature interval,bound water content,permeability and shear strength of Guilin red clay are obtained as well.The results show that the content of K in red clay increases with the increase of KCl solution concentration.The zate potential on the surface of red clay particles increases because of the close adsorption of cations on its surface,which increases the repulsion of K in the fixed layer to K in the diffusion layer and the thickness of the diffusion layer,resulting in the decrease of the weight loss temperature interval of weakly bound water and the increase of the weight loss temperature interval of strong bound water;with the increase of KCl solution concentration,the negative charge on the surface of red clay particles interacts with K in KCl solution,resulting in the increase of bound water,which mainly changes the content of weakly bound water;the viscosity resistance in red clay increases with the increase of bound water,resulting in the decreases of permeability and shear strength of red clay.The results can provide a reference for improving the engineering properties of red clay.