干湿-冻融循环下黄土力学特性及损伤机制研究  

Mechanical properties and damage mechanism of loess under dry-wet freeze-thaw cycle

作　　者：郅彬[1] 王尚杰 ZHI Bin;WANG Shang-jie(College of Architecture and Civil Engineering,Xi’an University of Science and Technology,Xi’an,Shaanxi 710054,China)

机构地区：[1]西安科技大学建筑与土木工程学院,陕西西安710054

出　　处：《岩土力学》2024年第4期1092-1102,共11页Rock and Soil Mechanics

基　　金：西安市岩土与地下工程重点实验室开放基金(No.XKLGUEKF21-03)。

摘　　要：为深入研究干湿-冻融循环对原状黄土力学特性的影响及细观损伤演化规律,通过不同次数干湿-冻融循环条件下的固结排水三轴剪切试验(consolidation drainage triaxial sheartest,CD)和核磁共振试验,从宏-细观角度分析其应力-应变曲线及强度指标变化规律和细观孔隙的损伤变化规律。在此基础之上,假定黄土微元强度分布服从复合函数,建立了黄土的损伤统计本构模型,并验证其适用性。研究结果表明:土体的应力-应变曲线表现为应变软化,并且随着循环次数的增大软化程度逐渐减弱。偏应力峰值随循环次数减小并逐渐趋于稳定,在循环2次时其衰减程度最大,不同围压下分别衰减了17.6%、23.2%、24.5%和18.1%。土体内胶结块在循环作用下发生破损,使得内部孔隙面积逐渐增大,主要为小孔隙向中大孔隙的转变,随着循环次数的增大,内部结构逐渐趋于稳定。The study aimed to investigate the influence of dry-wet freeze-thaw cycles on the mechanical properties of undisturbed loess and evolution of microscopic damage.In order to analyse the stress-strain curves and chang law of strengch index and mesoscopic damage of pores from a macro and meso perspective,the research employed consolidation drainage triaxial shear tests(CD)and nuclear magnetic resonance tests under varying dry-wet freeze-thaw cycle durations.On this basis,the strength distribution of loess was assumed to follow a composite function,a statistical damage constitutive model of loess was established and its applicability was verified.The key findings and observations are summarized as follows.The stress-strain curve of the soil exhibited strain softening,with the degree of softening gradually decreasing with an increase in the number of cycles.The peak value of deviatoric stress decreased with the number of cycles and tended to be stable gradually,and the attenuation degree was most significant at the second cycle,decreasing by 17.6%,23.2%,24.5%and 18.1%respectively under different confining pressures.The circulation action led to damage to the cemented block in the soil,resulting in a gradual increase in internal pore area,primarily due to the transformation of small pores into large pores.With an increase in the number of cycles,the internal structure of the soil gradually became more stable.

关 键 词：干湿-冻融循环 黄土 力学特性 细观损伤 损伤统计本构模型 

分 类 号：TU411.3[建筑科学—岩土工程]