叶绿泥石水化机理及膨胀特性的分子动力学  

Molecular Dynamics on Hydration Mechanism and Swelling Properties of Pennine

作　　者：张瑞 余飞[1] 佟凯文 黄康 张伟[1,2] 戴张俊 陈善雄[1] ZHANG Rui;YU Fei;TONG Kaiwen;HUANG Kang;ZAHNG Wei;DAI Zhangjun;CHEN Shanxiong(Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,Hubei,China;University of Chinese Academy of Sciences,Beijing 100049)

机构地区：[1]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,武汉430071 [2]中国科学院大学,北京100049

出　　处：《硅酸盐学报》2024年第7期2350-2363,共14页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(42172308);中国科学院青年创新促进会(2022331)。

摘　　要：高铁路基膨胀灾害工程实例发现,部分膨胀是由叶绿泥石水化膨胀引起的,但目前国内外学者对叶绿泥石膨胀特性研究较少,相关机理尚未明确。采用多尺度表征的方法研究了宏观和纳观尺度下叶绿泥石的膨胀特性,运用分子动力学模拟方法研究了叶绿泥石水化机理及动力学响应下的键能变化。结果表明:叶绿泥石具有一定的膨胀潜力。通过不同数量水分子的吸附试验,得到层间域极限数量为32个,吸附位置为硅氧骨干形成的六方空穴,且仅能形成1层饱和水分子层。随着水分子增多,膨胀加剧,直至达到极限,极限状态的晶格常数为a=21.52A,b=18.61A,c=14.54A。水化模型经室温恒压的动力学模拟,发现模拟过程中静电作用能贡献最多,van der Waals作用能次之,键伸缩能最少。随着水化的加剧,水分子之间的相互作用变弱,径向分布函数峰值右移,层间水分子扩散性增强,且表现出靠近滑石层的倾向,水氧与滑石层氢原子形成的氢键键长1.8A,层间水与黏土矿物的径向分布函数峰值右移,同时氢键中的氢原子与受体原子之间的距离增加,氢氧配位数增加,这导致氢键键长增加,键角减小,黏土层开始产生膨胀。Introduction Clay mineral crystals are mostly formed by stacking layers of silicon-oxygen tetrahedral sheets and aluminum–oxygen octahedral sheets.They basically have water absorption and expansion because of their unique layered crystal structure.Clay minerals after hydration and expansion usually cause serious engineering problems,which have a negative impact on engineering construction.They have received extensive research attention.It is generally believed that the hydration expansion of clay minerals is mainly divided into two stages,i.e.,crystal expansion and osmotic expansion.Crystal expansion is caused by the expansion of water molecules into the interlayer of clay minerals.Permeation expansion is due to the lattice substitution of clay minerals,which leads to the imbalance of valence and electricity of the crystal.Massive exchangeable ions are gathered on the surface of the crystal.After these ions are dissociated in water,they will repel each other with negative charge under the action of the diffusion double layer,resulting in expansion.Compared with osmotic expansion,the degree of crystal expansion is small,kaolinite,illite,pennine and other interlayer cation-free clay minerals do not have an expansibility.However,the problem of expansion disaster occurs under the working condition rich in pennine,indicating the research value of pennine hydration expansion.However,the water absorption characteristics,expansion characteristics and hydration mechanism of pennine in nano-scale are not yet clear,and related research needs to be carried out.In this paper,a molecular dynamics study on water absorption of mesophyll pennine was carried out to explain the hydration characteristics of mesophyll pennine nanocrystal structure.The changes of energy,structure and chemical bond of mesophyll pennine in the process of hydration expansion were discussed.Materials and method The ring cutter samples with different pennine contents (i.e.,0%,20%and 100%) were prepared with pennine mixed with quartz.The no-load expansion

关 键 词：叶绿泥石 水化膨胀 分子模拟 径向分布函数 

分 类 号：TU443[建筑科学—岩土工程]