摘要
土体渗蚀是导致堤坝失稳、路基坍塌等岩土工程灾害的重要因素。通过自主改进GDS三轴试验仪,增设颗粒流失收集装置,实时监测粉土质砂在渗蚀过程中的流量变化、细粒流失量及体应变发展,系统研究了水力梯度、围压和细粒含量对渗蚀机理及渗蚀后力学性能的影响。结果表明:渗蚀过程呈现明显的“堵塞-流失”双阶段特征,即渗蚀初期细粒迁移堵塞导致渗透系数降低,随后堵塞颗粒持续流失使渗透系数回升并最终超过初始值;渗透系数增量、细粒流失率及体应变均随水力梯度和细粒含量增加而增大,随围压增加而减小。此外,低水力梯度或高围压条件下,迁移细粒在粗粒间隙的积聚会暂时增强土体初始刚度和强度,但随应变增加此强化效应消失,导致土体强度整体下降。进一步证实了渗蚀引起的孔隙比变化是影响土体变形特性的关键因素,其增幅与最大体缩量呈正相关。研究成果揭示了粉土质砂渗蚀发展规律及其对力学性能的影响机制,可为评估渗蚀引发的工程灾害风险提供理论依据。
Internal erosion of soil is a major factor leading to engineering hazards such as dam instability and roadbed collapse.A modified GDS triaxial apparatus with a particle collection system was developed to monitor the real-time changes in flow rate,fine particle loss,and volumetric strain during the erosion process of silty sand.The effects of hydraulic gradient,confining pressure,and fines content on the erosion mechanism and post-erosion mechanical properties were systematically investigated.Results show that the erosion process exhibits distinct“clogging-loss”dual stages:the permeability coefficient initially decreases due to fine particle migration and clogging,followed by continuous loss of clogged particles leading to a recovery and eventual increase beyond the initial value.The increments in permeability coefficient,fine particle loss rate,and volumetric strain all increase with increasing hydraulic gradient and fines content but decrease with increasing confining pressure.Additionally,under low hydraulic gradient or high confining pressure conditions,the accumulation of migrating fines in the voids between coarse particles temporarily enhances the initial stiffness and strength of the soil.However,this strengthening effect diminishes with increasing strain,resulting in an overall decrease in soil strength.Furthermore,it is confirmed that the void ratio changes induced by erosion are the key factor affecting soil deformation characteristics,with a positive correlation between void ratio increment and maximum volumetric compression.The research results reveal the evolution patterns of internal erosion in silty sand and its effects on mechanical properties,providing theoretical basis for assessing the risk of erosion-induced engineering hazards.
作者
于鹏强
王四军
郭雨茜
赵德斌
刘洋
YU Peng-qiang;WANG Si-jun;GUO Yu-xi;ZHAO De-bin;LIU Yang(School of Future Cities,University of Science and Technology Beijing,Beijing 100083,China;The Second Engineering Company Ltd.of CCCC Third Highway Engineering Co.,Ltd.,Tianjin 301800,China;China Railway 15th Bureau Group Co.,Ltd.,Shanghai 200070,China)
出处
《科学技术与工程》
北大核心
2025年第24期10374-10385,共12页
Science Technology and Engineering
基金
国家自然科学基金(52278327)
北京市自然科学基金(8222020)。
关键词
粉土质砂
渗流内蚀
三轴试验
围压
水力梯度
细粒含量
silty sand
infiltration erosion
triaxial test
confining pressure
hydraulic gradient
fine content
