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基于临界状态理论的砾石土边坡降雨条件下的失稳机制试验研究
Alternative TitleExperimental Study on Failure Mechanism of Gravelly Soil Slope on Precipitation Condition Based on Critical State Theory
Language中文
廖丽萍
Thesis Advisor何思明 ; 邹代华
2013
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name博士
Degree Discipline岩土工程
Keyword砾石土边坡 失稳机制 滑坡 泥石流 临界孔隙比 临界状态线
Abstract降雨条件下,震区砾石土边坡易失稳诱发滑坡、泥石流等地质灾害。在砾石土边坡失稳过程中,土体由相对稳定状态逐渐过渡到临界状态。目前关于砾石土边坡失稳的研究,无论是室内模型实验还是野外定点观测,对降雨条件下砾石土天然孔隙比(干密度)、应力应变特征、临界状态的认识不足,制约了研究的进一步深入。由于土体的应力应变特征、干密度和孔隙比的变化规律及其临界状态缺乏充分的试验数据支撑,多数关于边坡失稳及其转化成泥石流的研究成果均是采用三轴试验的结果来定性解释,因此,基于临界状态土力学的砾石土边坡失稳机制等方面的研究基本上还处于空白状态。 论文通过采用土体工程性质测试、野外原位观测、室内模型实验、理论分析等研究方法,取得了以下研究成果: 1) 总结了砾石土的力学性质、砾石土边坡降雨条件下的破坏类型和活动特征;围绕次生地质灾害的形成条件,基于发育特征、分布规律、演化趋势,提出震区潜在泥石流、不稳定边坡的野外识别诊断技术,为都汶公路潜在次生地质灾害的识别与诊断提供理论基础。 2) 选取初始干密度、初始质量含水率、坡度、降雨强度、物质颗粒级配(不同的粘粒含量)这5 个因素,系统地开展了单一变量与多变量人工水槽模型实验及原位试验,通过分析砾石土边坡失稳与泥石流启动的现象与土体颗粒级配变化规律,研究在降雨入渗条件下边坡失稳过程中土体孔隙比的变化路径,探讨不同工况条件下滑坡从变形到失稳过程中的土体孔隙比的变化规律。 3) 通过固结排水三轴试验,分析和研究了原始级配与变级配砾石土的临界状态即临界孔隙比,提出了描述砾石土临界状态变化规律的数学表达式。 4) 基于临界状态土力学理论与野外观测数据,根据临近破坏时砾石土边坡土体的状态(用孔隙比e与平均有效应力p'表征)在临界状态线(即ec-ln p'关系曲线)的相对位置来判断单一变量试验与多变量试验中土体的力学性状。 5) 总结归纳了基于临界状态的砾石土边坡的失稳机制,提出其相关影响因子的定量指标。
Other AbstractLandslide and debris flow in seismic area are readily to motivate in gravel soil slope when it suffers heavy precipitation. The nature of slope failure in gravel soil can contributed to evolved process from relatively steady condition to critical state. As for the current explanation for the gravel soil failure, it is obvious that the severe shortage of understanding in natural soil void ratio or dry density, the relationship between stress and strain, the critical state, all of which collected from indoor testing or field experiments, have hitherto prevented scientists from further investigation. Owing to insufficiency of serious field testing data, most precedent works more or less got through a qualitative approach of indoor triaxial test, instead of checking up the changes of stress and strain characteristic during experiments, and the variation of density and soil void ratio. As a consequence, it leads to a poor interpretation of failure mechanism of gravel soil slope. Based on above review, this dissertation is to make a systematic research on the gravel soil slope failure by principals of critical soil mechanism. By triaxial testing, field observations, model experiments, numerical simulation and theory analysis, following scientific discoveries were made: 1) An extensive scientific investigation on mechanical properties, failure types and activity features of gravel soil slope was presented systematically. According to formation conditions, development characteristics, distribution rules and evolution trend of potential debris flow and landslide, the discrimination method for potential debris flow and landslide was attained. 2) A series artificial flume experiments involving with five factors including initial dry density, initial mass moisture, slope, rain intensity and grain composition(the different clay content) were carried out. The variation laws of void ratio in these experiments were explored by analyzing failure phenomena, motivation of debris flow and variation laws of grain composition. 3) Through consolidation shear drained tests, the critical void ratios of gravel soil with the natural, variable grain composition were studied, the formulas of critical state line were attained. 4) The relative positions of soil state were determined based on critical state line( line) and data of field observations, then the mechanical properties of gravel soil were attained. 5) The failure mechanism of gravel soil based on critical state soil mechanics was investigated on, and quantitative index influencing failure mechanism were explored.
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/7048
Collection山地灾害与地表过程重点实验室
Recommended Citation
GB/T 7714
廖丽萍. 基于临界状态理论的砾石土边坡降雨条件下的失稳机制试验研究[D]. 北京. 中国科学院研究生院,2013.
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