饱和黏土平均粒间应力的确定方法

A method for determining average intergranular stresses in saturated clays

粒间作用力是控制土体强度和压缩特性的重要参量,但由于黏土中矿物颗粒与孔隙水间存在复杂的物理化学作用,其粒间应力及其变化规律一直无法确定。对泥浆重塑样在不同水化学条件下进行了一系列黏土一维侧限压缩试验,探讨不同浓度的NaCl溶液对饱和黏土压缩过程的影响,并确定土中粒间应力的大小及其变化规律。结果表明:同一级固结应力作用下,随替换溶液浓度的增加渗透固结变形量增大;对于相同浓度的孔隙溶液,固结应力越大,相应的渗透固结变形量越小。根据太沙基有效应力原理,提出了一种利用渗透固结变形来计算平均粒间应力的方法,在此基础上确立了粒间应力(或广义渗透压力)相对变化量与浓度和孔隙比之间的定量关系。该研究提供了一种简单有效的确定饱和黏土粒间应力的方法,为今后校正和验证多场耦合下土本构理论模型奠定基础。

The shear strength and compressibility of soils are largely controlled by intergranular interactions.For clayey soils,however,the intergranular stresses remain elusive experimentally due to the complex physicochemical interactions between the clay minerals and pore water.To explore the effect of Na Cl solution with different concentration on clay compression and to determine the intergranular stresses,a series of oedometer experiments was performed on the remolded samples prepared from a slurry mud.It is shown that at the same vertical stress,the deformation during osmotic consolidation increases with pore water concentration,and at the same concentration,the deformation during osmotic consolidation decreases as the vertical stress increases.Based on Terzaghi’s effective stress principle,the average intergranular stress is calculated based on the osmosis-induced deformation,and the dependence of intergranular stress(or the generalized osmotic pressure)variation on the pore water concentration and void ratio(i.e.,dry density)is determined.This paper provides a simple and yet effective approach to determine the intergranular stresses for clayey soils,which is helpful in calibrating the constitutive model of soils with multiple coupled physicochemical processes.