不同温度下高岭石变形及破坏机理的分子动力学模拟  

Molecular dynamics simulation of deformation and failure mechanism of kaolinite at different temperatures

作　　者：何满潮[1] 韩宗芳 杨华[1,2] He Manchao;Han Zongfang;Yang Hua(State Key Laboratory for GeoMechanics and Deep Underground Engineering,Beijing 100083,China;School of Mechanic and Civil Engineering,China University of Mining and Technology,Beijing 100083,China)

机构地区：[1]深部岩土力学与地下工程国家重点实验室,北京100083 [2]中国矿业大学(北京)力学与建筑工程学院,北京100083

出　　处：《矿业科学学报》2019年第1期8-16,共9页Journal of Mining Science and Technology

基　　金：国家重点研发计划(2016YFC0600901)

摘　　要：在不同温度条件下,运用分子动力学方法对高岭石OA、OB、OC三个方向进行单轴拉伸模拟,从微观角度还原高岭石变形及破坏的过程,研究了高岭石在不同温度下的微观结构变化、拉伸过程中的变形机理以及拉伸力学性能的温度效应。结果表明,弛豫后的高岭石随着温度升高产生热膨胀;沿OA和OB方向的拉伸,一旦裂纹形核出现,裂纹将会快速扩展,从而导致应力急剧下降,OC方向在拉伸过程中会出现整层分离的现象,构型将随着氢键作用的消失而发生破坏。高岭石力学性能对温度具有很强的依赖性:抗拉强度、杨氏模量与温度呈负相关关系;随温度升高,拉伸极限应变和残余强度呈降低的趋势,强度衰减系数呈增加的趋势,OC方向受温度影响最大,OB方向次之,OA方向最小。Uniaxial tensile simulations were carried out in OA,OB and OC directions of kaolinite at different temperatures by using molecular dynamics simulations.The deformation and failure processes of kaolinite were studied at the atomistic scale.The change of microstructure,deformation mechanism and temperature effect of tensile mechanical properties of kaolinite at different temperatures were also analyzed.This work would be helpful to understand the mechanisms of large deformation and failure of soft rock.The results indicated that the increasing of temperature results in the thermal expansion of kaolinite after relaxation.Once the crack nucleation appears,it propagates very quickly and leads to a sharp decrease in stress along OA and OB loading directions.The layer separation occurs during loading along OC direction,while the structure could fail since the hydrogen bonds are broken.The mechanical properties of kaolinite have a strong dependence on temperature.There is a negative correlation between tensile strength,Young’s modulus and temperature.With the increase of temperature,the tensile ultimate strain and residual strength tend to decrease,and the strength attenuation coefficient tend to increase.In addition,OC direction is the most affected by the temperature,followed by OB direction,and OA direction is the least affected.

关 键 词：高岭石 分子动力学 力学性能 变形机理 温度效应 

分 类 号：TD313[矿业工程—矿井建设]