考虑循环荷载下颗粒破碎的宕渣路基渗透系数预测
Prediction of permeability coefficients for slag embankments considering particle fragmentation subjected to cyclic loading
张玲 1陈昀灏 1徐林荣 2彭文哲1
作者信息
- 1. 湖南大学 土木工程学院,湖南 长沙 410082
- 2. 中南大学 土木工程学院,湖南 长沙 410075;高速铁路建造技术国家工程研究中心,湖南 长沙 410075
- 折叠
摘要
本文旨在揭示循环荷载作用下中-强风化泥岩宕渣破碎行为与渗透特性的内在机理.利用PFC 6.03D进行循环三轴数值模拟,借助内置Fish语言监测不同循环加载次数下宕渣试样级配、破碎率、孔隙率的动态演化规律.通过对不同加载次数下的土体级配曲线形态的分析,给出一种能描述土类多种连续级配形态的负指数型级配表达式,并讨论了其普适性.以级配方程为枢纽,构建了综合考虑颗粒组构、孔隙特征影响的渗流路径的迂曲度模型.同时,以迂曲度为修正系数,对斯托克斯孔隙流渗透系数公式进行修正.由此实现了考虑循环荷载作用下颗粒破碎的中-强风化泥岩宕渣路基渗透系数预测.研究结果表明:位点深度加深,修正潜在破碎势B*p明显降低,而修正相对破碎势B*r与位点深度并无明显关联,B*r变化趋势可分为迅速增长、缓慢增长、收敛3个阶段;孔隙率变化呈现类似规律.所提出的负指数级配方程对4种典型级配(凹形、S形、类直线形、凸形)均具有良好适用性.修正迂曲度略大于仅考虑单一颗粒形态的迂曲度,复杂的颗粒形态使得流域内流线更加曲折,引起整体迂曲度增大.渗透系数k敛随B*r增长呈抛物线状衰减,且位点越浅,k衰减愈明显;存在临界加载振次使各位点k值收敛.本研究可为中-强风化泥岩宕渣路基服役状态评估提供新思路.
Abstract
This investigation was aimed at revealing the intrinsic mechanism between the slag(referring specifically to the medium-strongly weathered mudstone)crushing behavior caused by cyclic loading and its permeability characteristics.The simulation of cyclic triaxial tests was conducted through PFC 6.03D.The built-in Fish language was utilized to monitor the dynamic evolution of particle gradation,crushing rate,and porosity of slag subjected to various loading cycles.A negative exponential continuous gradation equation to describe various continuous gradation of soils was proposed by analyzing the gradation characteristics of slag under different loading cycles,and its universality was discussed.Taking the gradation equation as a pivot,a seepage tortuosity Γ model that comprehensively integrated the effects of particle grouping,and pore characteristics was constructed and based on which the Stokes pore flow permeability coefficient formula was modified.This enabled the prediction of permeability coefficients of slag(medium-strongly weathered mudstone)embankments considering particle fragmentation subjected to cyclic loading.The outcomes are as follows.As the depth of the site deepens,the modified potential breakage potential B*p decreases significantly,while the modified relative breakage rate B*r is not significantly correlated with the depth,and the tendencies of B*r can be divided into three stages:rapid growth,slow growth,and convergence stage.The porosity demonstrates similar patterns.The negative exponential continuous grading equation has great applicability to four typical gradations(concave,S-shaped,linear-like,and convex).The modified tortuosity is slightly larger than that considering the single granular shape.The complex granular shape makes the flow lines more tortuous in the region,causing the overall tortuosity to increase.The permeability coefficient k decays parabolically with B*r growth,and the shallower the locus,the more pronounced the k decay.There is a critical loading cycle making it converge at each site.The investigation can provide new insights for assessing the service performance of the slag(medium-strongly weathered mudstone)embankment.
关键词
循环荷载/宕渣路基/颗粒破碎/迂曲度/渗透系数Key words
cyclic loading/slag embankment/particle fragmentation/tortuosity/permeability coefficient引用本文复制引用
基金项目
国家重点研发计划(SQ2022YFB2300030-06)
国家自然科学基金资助项目(U2268213)
国家自然科学基金资助项目(52378340)
国家自然科学基金资助项目(52078205)
国家自然科学基金资助项目(42172322)
岩土力学与工程国家重点实验室开放基金资助项目(SKLGME022016)
湖南省研究生科研创新一般项目(QL20230104)
出版年
2024
国家科技期刊平台
NSTL
万方数据