土石混合体大型三轴剪切力学特性的颗粒级配效应  

Particle Size Distribution Effect on Large-scale Triaxial Shear Mechanical Properties of Soil-rock Mixture

作　　者：张超 俞缙[2] 朱东平[3] 龚晶汉 李哲涵 ZHANG Chao;YU Jin;ZHU Dong-ping;GONG Jing-han;LI Zhe-han(Hunan Provincial Key Laboratory of Geotechnical Engineering for Stability Control and Health Monitoring,Hunan University of Science and Technology,Xiangtan 411201,Hunan,China;Fujian Research Center for Tunneling and Urban Underground Space Engineering,Huaqiao University,Xiamen 361021,Fujian,China;China Railway No.5 Engineering Group Co.Ltd.,Changsha 410021,Hunan,China;College of Civil Engineering,Central South University,Changsha 410075,Hunan,China)

机构地区：[1]湖南科技大学岩土工程稳定控制与健康监测湖南省重点实验室,湖南湘潭411201 [2]华侨大学福建省隧道与城市地下空间工程技术研究中心,福建厦门361021 [3]中铁五局集团有限公司,湖南长沙410021 [4]中南大学土木工程学院,湖南长沙410075

出　　处：《中国公路学报》2024年第10期61-72,共12页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(42077254);中国博士后科学基金项目(2023MD744275);岩土工程稳定控制与健康监测湖南省重点实验室开放基金项目(E22308)。

摘　　要：土石混合体作为特殊的岩土材料日益受到重视,合理设定级配参数(不均匀系数C_(u)和曲率系数C_(c))对保障高填路堤安全至关重要。为了研究土石混合体剪切力学特性的颗粒级配效应,首先制备A组(C_(c)定值,C_(u)变化)和B组(C_(u)定值,C_(c)变化)土石混合填料,开展了大型三轴压缩试验,分析级配参数对土石混合体偏应力强度σ_(f)、初始变形模量E_(i)、黏聚力c及内摩擦角φ的影响;然后结合Janbu经验公式探讨参数K、n和极限偏应力强度(σ_(1)-σ_(3))_(ult)分别与级配参数之间的关系,提出考虑级配特征和应力状态影响的邓肯-张模型参数确定方法,建立改进邓肯-张模型;最后探讨级配参数对土石混合体粒组结构及其空间分布特征的影响,提出3种基质-块石运动概化模型。结果表明:σ_(f)-C_(u)关系曲线呈单峰型,峰值后强度降幅随围压的增大而增大,σ_(f)-C_(c)关系曲线呈似线性增大,但随围压的增大逐渐转为凸型非线性增大;E_(i)-C_(u)关系曲线呈峰谷交错型,但随围压的增大逐渐转为单峰型,E_(i)-C_(c)关系曲线呈似线性增大,其曲线平均变化率随围压的增大而增大;c-C_(u)关系曲线初期保持水平但随后递增,c-C_(c)关系曲线呈单谷型且在C_(c)=1.74时取得最小值;φ-C_(u)关系曲线呈单峰型且在C_(u)=10.0时取得峰值,φ-C_(c)关系曲线呈凸型非线性且在C_(c)=1.74处曲率最大。改进邓肯-张模型能够有效预测考虑级配特征和应力状态影响的土石混合体大型三轴剪切变形破坏过程。基质-块石运动概化模型能够有效阐释密实-骨架结构特征变化引起的土石混合体大型三轴剪切力学特性。Soil-rock mixtures are special geotechnical materials that have recently attracted considerable attention.It is very important to establish reasonable grading parameters(coefficient of nonuniformity C_(u)and coefficient of curvature C_(c))to ensure the safety of high-fill embankments.To study the effect of particle size distribution on the shear mechanical properties of soil-rock mixtures,two groups of soil-rock mixture fillers were prepared.Group A had a constant value of C_(c)and a varying C_(u),whereas group B had a constant value of C_(u)and a varying C_(c).Large-scale triaxial compression tests were then performed to analyze the influence of the grading parameters on the deviatoric stress strengthσ_(f),initial deformation modulus E_(i),cohesion c,and internal friction angleφ.Subsequently,the relationships between parameters K and n,ultimate deviatoric stress intensity(σ_(1)-σ_(3))_(ult),and grading parameters were analyzed in conjunction with the Janbu empirical formula.Additionally,parameter determination methods for the Duncan-Chang model considering the influence of grading characteristics and stress state were proposed,and an improved Duncan-Chang model was established.Finally,the effects of the grading parameters on the particle structure and spatial distribution characteristics of the soil-rock mixture were determined,and three generalized models of matrix rock mass movement were proposed.The results show that theσ_(f)-C_(u)relationship curve exhibits a single peak,and the strength reduction after the peak value increases with increasing confining pressure.Theσ_(f)-C_(c)relationship curve displays a linear increase,but gradually becomes convex and non-linear with an increase in the confining pressure.The E_(i)-C_(u)relationship curve exhibits a peak-valley alternating type,but gradually transitions to a single peak type with an increase in confining pressure.The E_(i)-C_(c)relationship curve shows a linear increase,with the average rate of change increasing in conjunction with the increase in con

关 键 词：路基工程 土石混合体 大型三轴试验 级配效应 本构模型 

分 类 号：U416.1[交通运输工程—道路与铁道工程]