了解蒙脱石在拉伸状态下的力学行为在地球科学、岩土力学等领域至关重要，但现有理论和方法难以在小间距范围内预测其水化力学性质及关键机理。通过编写施加应力-计算应变Perl语言脚本，进行不同水化量蒙脱石拉伸应力下的分子动力学计算模拟与应力-应变分析，确定其不同应力阶段的力学特性、相互作用机制和微观结构演化。结果表明：蒙脱石内层水化对极限应力和拉伸模量的弱化效应明显，且在水化初期弱化幅度会更大；体积水化膨胀主要源于晶格长度c的线性增长。Z方向的拉伸模量远小于平面内，即应力对表面Z方向的力学行为影响最大，达到极限拉应力后，会出现整层分离的破坏现象；内层是大部分形变的主要原因，并且支配着蒙脱石的拉伸力学性能；Z方向拉应力主要造成晶格长度c和晶格角β的增大，而在X和Y方向拉应力下主要发生β的减小和增大。层电荷密度越高，结合水膜越密实，形成的氢键数目越多，体积和晶格长度c越小，抗拉力学性能也越强。

Knowing the mechanical behavior of montmorillonite under tensile stress is crucial in earth sciences and geomechanics. However, existing theories and methods are difficult to predict its hydration mechanical properties and inner mechanism within the small layer-spacing. In this paper, through the stress-strain script, tensile molecular dynamics simulation and stress-strain analysis are conducted on montmorillonilte with different hydration amounts to determine the mechanical properties, interaction mechanism and microstructure evolution. It is found that the weakening effect of interlayer hydration on the ultimate stress and tensile modulus is obvious, and the weakening effect is larger in the early stage of hydration; the volume expansion with hydration results from the linear increase in lattice length c. The Z direction tensile modulus is much smaller than the in-plane, that is, the stress has the greatest influence on the mechanical behavior of surface Z direction; after reaching the ultimate tensile stress, the layer separation failure occurs; besides, the interlayer is the main cause of deformation and dominates the tensile mechanical properties of montmorillonite; the tensile stress in the Z direction causes the increase of lattice length c and lattice angle β, while in the X and Y directions, it is mainly the decrease and increase of β. The higher the layer charge density, the denser the bound-water film, the more hydrogen bonds formed, the smaller the volume and lattice length c, and the stronger the tensile mechanical properties.

TU443

国家自然科学基金（11672108）；国际（地区）合作与交流项目（11911530692）