CAJ | 학술논문

石碑塬滑坡是1920年海原地震触发的大型黄土流滑，认识其破坏特征与发生机制对于黄土边坡长距离液化失稳机制的研究非常重要。对石碑塬黄土滑坡的调查和研究表明，饱和黄土或高含水率黄土具有很高的液化势和流态破坏势，在强震作用下，饱和黄土易发生液化或流滑。对石碑塬滑坡的7组原状黄土样品进行振动三轴剪切试验，并结合其微观特征分析，探讨了循环振动荷载作用下的饱和黄土孔隙水压力-应变增长模型，分析了振动液化过程中液化应力比与黄土粒度组成、土体微观结构参数及饱和度之间的关系。结果表明：黏粒含量越低，振动作用下饱和黄土孔隙水压力响应越快，液化应力比越低；黄土孔隙比越大，孔隙结构分形维数越大，液化应力比越低，振动液化后黄土孔隙分形维数降低，结构较液化之前更为致密；饱和度对黄土粒间胶结物质的赋存状态及黄土结构强度影响很大，同一土体饱和度越高，溶滤于孔隙水中的离子浓度越高，土体粒间接触点（或胶结点）越容易发生断裂，使得黄土结构强度降低，液化应力比降低。
석비원활파시1920년해원지진촉발적대형황토류활，인식기파배특정여발생궤제대우황토변파장거리액화실은궤제적연구비상중요。대석비원황토활파적조사화연구표명，포화황토혹고함수솔황토구유흔고적액화세화류태파배세，재강진작용하，포화황토역발생액화혹류활。대석비원활파적7조원상황토양품진행진동삼축전절시험，병결합기미관특정분석，탐토료순배진동하재작용하적포화황토공극수압력-응변증장모형，분석료진동액화과정중액화응력비여황토립도조성、토체미관결구삼수급포화도지간적관계。결과표명：점립함량월저，진동작용하포화황토공극수압력향응월쾌，액화응력비월저；황토공극비월대，공극결구분형유수월대，액화응력비월저，진동액화후황토공극분형유수강저，결구교액화지전경위치밀；포화도대황토립간효결물질적부존상태급황토결구강도영향흔대，동일토체포화도월고，용려우공극수중적리자농도월고，토체립간접촉점（혹효결점）월용역발생단렬，사득황토결구강도강저，액화응력비강저。
The Shibeiyuan landslide is a typically large loess flow slide which was triggered by Haiyuan earthquake in 1920. Understanding its behavior and mechanism is very important to study liquefied slope failures with long travel distance in the loess area. The in-situ investigation of the Shibeiyuan landslide shows that the saturated loess or the loess with high water content has high liquefaction and destructive potential which could cause liquefaction or flow slide under strong earthquake. The dynamic triaxial shear tests are performed on seven intact soil specimens taken from three places at the landslide. In addition, the scanning electron microscope (SEM) microscopic characteristics of the soil specimens are used to clarify the shear behaviors of these soil specimens. According to the results, the relation between water pore pressure and strain, as well as the relations between liquefied stress ratio and particle size, microstructure parameter, and degree of saturation are analyzed. The analytical results reveal that the liquefied stress ratio decreases and pore pressure response is stronger with the increasing of clay content. Meanwhile, the specimens with greater porosity have greater fractal dimension and less liquefied stress ratio. Moreover, the liquefied specimens are denser and its fractal dimension is greater compared to that before the liquefaction. Additionally, the degree of saturation has great influence on the state of interparticle cement and the microstructure in loess. The saturating process shows that the ionic concentration of the pore water is greater and the rupture of the interparticle contacts is easier when the degree of saturation becomes greater. As a result, the structural strength of the specimens decreases, leading to the decrease of the liquefaction stress ratio.