摘要
离散元法(DEM)是研究非饱和土力学性质的重要方法,其模拟的可靠性取决于非饱和接触模型细观参数的准确标定。目前,对非饱和接触模型细观参数的标定方法缺乏系统研究。本文提出一种基于柔性边界的标定离散元(DEM)中非饱和接触模型细观参数的方法,对非饱和接触模型细观参数进行系统标定,并通过参数敏感性分析揭示了非饱和接触模型中细观参数与宏观力学性质的相关性。首先,通过正交试验设计对细观参数的取值范围进行优化,分析细观参数对宏观响应的敏感性,结果表明:非饱和土的割线模量E_(50)主要受摩擦系数μ、吸力ψ、杨氏模量E的影响,影响程度为μ>ψ>E;非饱和土的峰值强度Sp主要受吸力ψ、摩擦系数μ的影响,其影响程度为ψ>μ>E。其次,根据敏感性分析结果确定相关宏观响应的显著影响参数,利用基于中心复合试验设计(CCD)的响应面分析方法建立非饱和土宏观力学参数与显著影响参数之间的回归方程。再次,根据回归方程建立非饱和土细观参数的最优化模型,使用MATLAB中的FMINCON函数对其进行求解,获得细观参数的最优解。最后,利用获得的最优参数,模拟不同围压下非饱和土的三轴试验并与试验结果进行对比,验证所标定参数的有效性。该方法可为进一步分析非饱和土的细观力学性质提供基础。
Discrete element method(DEM)is an important method to study the mechanical properties of unsaturated soils.The reliability of numerical simulation depends on the accurate calibration of the mesoscopic parameters of the unsaturated contact model.At present,there is a lack of systematic study on the calibration method of mesoscopic parameters of unsaturated contact model.In this paper,a method of calibrating the mesoscopic parameters of unsaturated contact model in DEM based on flexible boundary was proposed.The mesoscopic parameters of the unsaturated contact model were systematically calibrated,and the correlation between the mesoscopic parameters and the macro response of the unsaturated contact model was revealed through parameter sensitivity analysis.First,the range of mesoscopic parameters was optimized through orthogonal test design,and its sensitivity to macro response was analyzed.The sensitivity analysis results showed that the secant modulus(E_(50))of unsaturated soil was mainly affected by the friction coefficient(μ),suction(ψ),and Young's modulus(E),and the degree of influence wasμ>ψ>E;The peak strength(Sp)of unsaturated soil was mainly affected byψandμ,and the degree of influence wasψ>μ>E.Secondly,according to the results of sensitivity analysis,the significant influence parameters of the relevant macroscopic response were determined,and the regression equation between the macroscopic parameters and the significant mesoscopic parameters of the unsaturated contact model was established by using the response surface analysis method based on the central composite test design(CCD).Thirdly,the most optimized model of mesoscopic parameters of unsaturated soil was established according to the regression equation,and the FMINCON function in MATLAB was used to solve it to obtain the optimal solution of mesoscopic parameters.Finally,the triaxial tests of unsaturated soil under different confining pressures were simulated by using the obtained parameters,which were compared with the laboratory tests to verify the validity of the calibrated parameters.This method provided a basis for further analysis of the mesoscopic mechanical properties of unsaturated soils.
作者
张杰
聂如松
黄茂桐
谭永长
肖玲
ZHANG Jie;NIE Rusong;HUANG Maotong;TAN Yongchang;XIAO Ling(School of Civil Eng.,Central South Univ.,Changsha 410075,China;MOE Key Lab.of Eng.Structures of Heavy Haul Railway,Central South Univ.,Changsha 410075,China)
出处
《工程科学与技术》
EI
CAS
CSCD
北大核心
2023年第6期132-141,共10页
Advanced Engineering Sciences
基金
国家自然科学基金项目(51878666)
中国铁路乌鲁木齐局集团有限公司科技研究开发计划课题(WLMQ–KGHZGS–HRTL–GGB–2020–0032)
省部共建交通工程结构力学行为与系统安全国家重点实验室开发课题(KF2021–01)。
关键词
非饱和土
柔性边界
细观参数标定
三轴试验
离散元
unsaturated soil
flexible boundary
mesoscopic parameter calibration
triaxial test
DEM
