双电层理论与高庙子膨润土的体变特征

黏性土中土体颗粒（矿物颗粒）带有负电荷，周围存在电场。在静电引力与布朗运动（热运动）作用下，紧邻土体颗粒表面处静电引力最强，水化离子和极性分子牢牢地被吸附在颗粒表面附近形成固定层。由固定层向外，静电引力逐渐减小，水化离子和极性分子的活动性逐渐增大，形成扩散层。固定层和扩散层中的阳离子（反离子层）与土粒表面负电荷共同构成双电层。根据双电层理论，当给定两个黏土片层之间的距离时，渗透压力可以由两个片层中轴线处的离子浓度来求取。同样，对于给定的渗透压力和中轴线处的离子浓度，便可以确定两个片层之间的距离。采用渗析法吸力控制技术与压汞仪法（MIP）微观结构试验手段，研究了低吸力范围内、自由膨胀条件下高压实高庙子膨润土的土水特性与体变特征，同时采用双电层理论估算了高庙子膨润土水化过程中的自由膨胀量，并将估算值与试验实测值进行了对比分析。在使用孔率计法试验结果求取试样孔隙比时考虑了压汞仪出力能力影响，采用线性延伸方法估算了残余孔隙量。研究结果显示，低吸力范围内，由双电层理论，估算的高压实高庙子膨润土的自由体积膨胀量与试验数据吻合较好，但随着吸力的进一步减小，两者之间的误差有增大的趋势，文中对出现这一偏差的原因进行了分析探讨。

Diffuse double layer theory and volume change behavior of densely compacted Gaomiaozi bentonite

In clayey soil, soil particles generally possess negative ions, and form an electronic field nearby the particles. With the function of electronic attraction force and Brown (thermal) movement force, electronic attraction force is much stronger nearby the surface of soil particles, ions and polar molecules are closely attracted to particles surface that forms a close layer around the particle. Outside this layer, the electronic attraction force decreases as the distance increase from the surface of the particle, and they form a dissipative layer. Ions in the dissipative layer and negative ions in the soil particles surface form diffuse double layer. Based on diffuse double layer theory, when the distance between two clay planets is known, the seepage force can calculate using the ion concentration at the middle plane between two planets. In the same way, the ion concentration at the middle plane between two planets is known, the distance between two planets can be calculated. The soil water characteristics of densely compacted Gaomiaozi bentonite has been obtained using osmotic and vapor phase techniques under free swelling conditions. At the same time, the volume change behavior of Gaomiaozi bentonite under unconfined conditions has been calculated using diffuse double layer theory. Comparison between calculated results and test data has also made. Results show that there is a good consistence between calculated results and testing records for the volume change of densely compacted Gaomiaozi bentonite under low suction.