非饱和黄土侧限压缩和湿陷试验的宏微观离散元特性分析  

Macro-microscopical Discrete Element Characteristics of Confined Compression and Wetting Test for Unsaturated Loess

作　　者：陈宝[1,2] 柳超凡 邓荣升 周一鸣 CHEN Bao;LIU Chaofan;DENG Rongsheng;ZHOU Yiming(College of Civil Eng.,Tongji Univ.,Shanghai 200092,China;Key Lab.of Geotechnical and Underground Eng.of Ministry of Education,Tongji Univ.,Shanghai 200092,China)

机构地区：[1]同济大学土木工程学院,上海200092 [2]同济大学岩土及地下工程教育部重点实验室,上海200092

出　　处：《工程科学与技术》2024年第5期212-220,共9页Advanced Engineering Sciences

基　　金：国网河南省电力公司科技项目(5217L0230008)。

摘　　要：为了深入探讨非饱和黄土在侧限压缩和快速增湿作用下的宏微观特性,本文采用颗粒流方法对黄土的力学特性开展了3维离散元仿真模拟分析。采用软胶结模型模拟了颗粒间的化学胶结作用,并考虑了颗粒间的范德华力和毛细力作用,着重分析了微观参数的变化规律。结果表明:软胶结接触模型能够准确地复现非饱和黄土侧限压缩和快速增湿试验中的力学响应行为。微观力学配位数随着竖向压力的增加而不断加速增长,同时颗粒间接触力与接触力矩均随含水率的增加呈现逐渐减小的趋势,而对于饱和试样则出现增长的情况。颗粒间的剪切破坏和拉破坏随着竖向压力的增加而逐渐增加,在大约100kPa达到最大值。随着含水率的增加,剪切破坏逐渐占据主导;此外,随着竖向压力的逐渐增加,应变能、滑动耗能与阻尼耗能逐渐增加,应变能数值远大于滑动耗能与阻尼耗能;应变能的增速随着竖向压力的增加逐渐加快,直至200kPa附近达到最大,含水率越大应变能终值越低;滑动耗能与阻尼耗能的终值均在小范围内波动。A three-dimensional discrete element simulation analysis is conducted using the particle flow method to explore unsaturated loess's macroscopic and microscopic characteristics under the effects of confined compression and rapid wetting.A soft cementation model accounts for the chemical cementation between particles,and inter-particle van der Waals and capillary forces are introduced.The study focuses on the variations in microscopic parameters by selecting suitable contact model parameters.The results showed that the soft cementation contact model accurately reproduces the mechanical properties of unsaturated loess during lateral compression and rapid humidification tests;the micromechanical coordination number increases with an increase in vertical pressure,whereas the inter-particle contact force and contact moment gradually decreases with an increase in water content.However,saturated specimens exhibited an inverse increase.In addition,the proportion of the damage state contact between particles increases with vertical pressure.As vertical pressure gradually grows,strain energy,sliding energy,and damping energy also rise,with strain energy significantly exceeding both sliding and damping energy values.The growth rate of strain energy accelerates with an increase in vertical pressure,peaking at approximately 200 kPa.In addition,strain energy grows gradually with an increase in vertical pressure until it reaches a maximum of around 200 kPa;higher water content correlates with lower final values of strain energy,while the final values of sliding energy and damping energy fluctuate within a small range.

关 键 词：黄土 离散单元 侧限压缩试验 湿陷试验 微观分析 

分 类 号：TU43[建筑科学—岩土工程]