The micro-mechanism controlling compressibility of saturated clay under high pressure: status and thoughts.

Based on the summary and analysis of the theories and models which were adequate to interpret the compressibility of saturated clay under low stress, such as diffuse double layer theory and nonparallel plate model, it was found that these theory or model failed to describe the bilinear shape of compression curves under high pressure. In order to facilitate a qualitative description of the complete compression process of clay, the total pore volume was classified into three different structural levels, which were called macropore, micropore and interlayer pore respectively. Under high pressure, apart from the expulsion of the free water enmeshed inside the aggregates and particles, the organized water molecules that adsorbed on the crystals were also be squeezed out layer by layer. And when two surfaces or particles approached closer to a few nanometers, continuum theories of attractive van der Waals and repulsive double-layer forces often failed to describe these interactions; other Non-DLVO forces came into play. Therefore, a new thought of study on the compressibility of saturated clay under high to has been proposed in the last part of this paper. By describing the specific arrangement of water molecules around the clay miner with the lattice density functional theory and conducting steered molecular dynamics simulation, the constitutive relation of saturated clay under high pressure could be constructed on the basis of molecular scale. [ABSTRACT FROM AUTHOR]