宁夏滨河粉土路基在循环荷载下的变形特性  

Deformation Characteristics of Silt Subgrade under Cyclic Loading in Ningxia Binhe District

作　　者：马文国 张刚[2,3] 封少博 杨有贞 MA Wenguo;ZHANG Gang;FENG Shaobo;YANG Youzhen(School of Physics and Electronic-Electrical Engineering,Ningxia University,Yinchuan 750021,China;Institute of Solid Mechanics,Ningxia University,Yinchuan 750021,China;Academic Journal Center,Ningxia University,Yinchuan 750021,China;College of Life Sciences,Yulin University,Yulin 719000,China)

机构地区：[1]宁夏大学物理与电子电气工程学院,宁夏银川750021 [2]宁夏大学固体力学研究所,宁夏银川750021 [3]宁夏大学学术期刊中心,宁夏银川750021 [4]榆林学院生命科学学院,陕西榆林719000

出　　处：《宁夏工程技术》2023年第1期37-43,共7页Ningxia Engineering Technology

基　　金：宁夏自然科学基金项目(2021AAC03095);国家自然科学基金项目(51768059);宁夏高等学校自然科学项目(NGY2017044)。

摘　　要：为了揭示宁夏滨河粉土路基在交通载荷下的变形机理,采用动三轴试验对宁夏滨河粉土重塑样本进行了逐级加载和循环荷载两种双向剪切工况下路基变形特性的研究,分析了路基粉土土样的破坏形式、滞回特性、骨干曲线、动弹性模量及阻尼比、滞回曲线面积和超静孔隙水压力变化的特点。结果表明:试样的破坏形式既有拉伸破坏也有压缩破坏,固结压力对土样破坏形式有着显著的影响;滞回曲线随循环应变的增加从封闭状态逐渐发展到不封闭的状态,直至土样出现大应变破坏;逐级加载下的骨干曲线随着动应力持续增大,应变迅速增大时骨干曲线的斜率开始减小,逐渐趋于水平状态;动弹性模量在弹塑性阶段随应变增大而大幅度地减小,在大应变时动弹性模量变化趋于平缓;阻尼比随动应变的增加在弹塑性阶段逐渐增大,在大应变时阻尼比变化趋于稳定;滞回曲线面积随着应变的增加呈近似于指数增长;孔压与应变的增长都是随着振次的增大而不断增长的,未出现类似黄土的结构崩溃式破坏,也不出现黄土试样在应变达到5%时孔压接近于固结压力的“初始液化”现象,滨河粉土的“初始液化”现象均出现在应变大于10%以后。In order to reveal the deformation mechanism of silt subgrade under traffic loading in Ningxia Binhe District,the deformation characteristics of roadbed under two kinds of two-way shear conditions,namely step-by-step loading and cyclic loading,were studied by using dynamic triaxial test on silt remodeling samples from Ningxia Binhe District,and the characteristics of damage form,hysteresis characteristics,backbone curve,dynamic elastic modulus and damping ratio,hysteresis curve area and super-static pore water pressure change of the samples were analyzed.The results show that the damage forms include both tensile type and compressive type,and the consolidation pressure has a significant influence on the damage forms.The hysteresis curve gradually develops from a closed state to an open state with the increase of cyclic strain until the soil samples are damaged by large strain.The backbone curve under the step-by-step loading continues to increase with the dynamic stress,and the slope of the backbone curve starts to decrease when the strain increases rapidly and gradually tends to a horizontal state.The dynamic modulus of elasticity decreases significantly with the increase of strain in the elastic-plastic stage,and the change of dynamic modulus of elasticity tends to be flat at large strain.The damping ratio increases gradually with the increase of dynamic strain in the elasticplastic stage,and the change of damping ratio tends to be stable at large strain.The area of hysteresis curve increases exponentially with the increase of strain.The growth of pore pressure and strain are increasing with the increase of vibrations,and there is no structural collapse damage similar to that of loess,nor is there the phenomenon of initial liquefaction of loess samples where the pore pressure is close to the consolidation pressure when the strain reaches 5%.The initial liquefaction of the silt samples occurs after the strain is greater than 10%.

关 键 词：滨河粉土 逐级加载 循环加载 滞回特性 骨干曲线 动弹性模量 阻尼比 超静孔隙水压力 

分 类 号：TU435[建筑科学—岩土工程]