分子动力学模拟中的钠基蒙脱石尺寸参数选取及其影响

蒙脱石作为主要的亲水性黏土矿物,因其特殊性质对岩土体工程性质有重要影响.分子动力学模拟为深入探究蒙脱石特性提供了有效手段,而分子模型的尺寸直接影响其模拟结果.基于LAMMPS软件及Paracloud超算云平台,从蒙脱石晶胞的力学特征的角度,通过分子动力学模拟研究了不同尺寸效应对蒙脱石性质的影响规律.研究结果表明:当晶胞形态不变时,蒙脱石晶胞的体积模量、剪切模量及弹性模量都在扩大2倍时达到最小值;当扩胞倍数相同时,蒙脱石晶胞在晶体延伸方向上的扩展尺寸对其力学性质影响较大,而在晶体堆叠方向上的扩展尺寸影响较小;蒙脱石的剪切模量、泊松比、弹性模量等受晶胞尺寸的影响较大,而体积模量则受晶胞形态的影响较大.

Selection of Dimension Parameters of Montmorillonite and Its Influence in Molecular Dynamics Simulation

As the main hydrophilic clay mineral, montmorillonite has an important influence on rock and soil mass because of its special properties. Molecular dynamics simulation provides an effective means for us to deeply explore the properties of montmorillonite, while the size of the molecular model directly affects the results. Based on Paracloud and LAMMPS software, the influence law of size effect on the properties of montmorillonite was studied through molecular dynamics simulation .The results show that (1)The volume modulus, shear modulus and elastic modulus of montmorillonite reach the minimum value when montmorillonite are expanded by 2 times.(2)The expansion size in the extension direction of montmorillonite had a great influence on the mechanical properties, but the expansion size in the stacking direction had a small influence. (3)The shear modulus, poisson"s ratio and elastic modulus of montmorilonite are greatly affected by cell size, while the volume modulus are greatly affected by cell shape.