IMHE OpenIR  > 山地灾害与地表过程重点实验室
泥石流源地土体力学性质的时空变化
Alternative Titlehe temporal and spatial variation of mechanical properties of debris flow particles in source
Language中文
苟万春
Thesis Advisor李泳
2016
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Name硕士
Degree Discipline岩土工程
Keyword标度参数 强度指标 渗透系数 孔隙水压力 随机崩塌
Other Abstract

通常泥石流源地土体发生非均匀崩塌破坏,坡面失稳过程涉及到渗透作用、孔隙水压力涨落、强度变化和坡面崩塌等过程。影响斜坡稳定性的因素很多,其中颗粒组成是影响土体破坏的重要因子之一。因此,本文从颗粒分布的角度来系统分析土体破坏活动相关的过程与破坏特征。基于土体颗粒组成的标度分布,以Mohr-Coulomb准则:τ=c+(σ-pw)tanφ(c为粘聚力,σ为法向应力,pw孔隙水压力,φ为内摩察角)为理论基础,结合土体颗分实验、室内强度实验、渗透实验和水槽实验,系统研究了土体颗粒组成的非均匀性,标度参数对强度参数、渗透指标的影响,土体破坏特征和孔隙水压力的演化特征及土体破坏活动与孔隙水压力变化的关系。在确定c、φ的分布特征及pw的时空变化后,分析抗剪强度τ的变化特征,从而揭示泥石流源地土体坡面活动的机理。主要取得了以下主要认识与结论:(1) 天然土体的标度参数(μ,Dc)服从Weibull分布:f(x;λ,k)=(k/λ)(x/λ)k-1exp(-(x/λ)k),Weibull分布参数(λ,k)随着坡度α增加而指数式减小:(λ,k)=(aλ,ak)exp((b λ,b k)α)。(2)土体粘聚力c、内摩擦角φ分别与μ、Dc存在幂函数关系:φ=AφDc-β, c=Acμa,因此,c~Weibull(λμaAc,kμ/a),φ~Weibull(λDcβAφ,kDc/β)。联合具体数据及τf=c+σtanφ,得出τf~Weibull(λ,k),具体的分布参数发生了改变。因此,土体非均匀分布决定了强度非均匀分布特征。 (3)渗透系数K与标度参数μ间有对数式关系,K随着μ的增加而减小。这表明土体渗透性主要取决于细颗粒组成,且具有随机性。(4)土体内部渗透性能的随机性导致孔压随机涨落,孔压随机涨落引起抗剪强度非均匀分布,促使坡体非均匀变形和随机破坏。整个坡面活动表现为随机崩塌,这可能是形成野外泥石流非稳定阵流现象的一种原因。

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Based on scale distribution and Mohr-Coulomb theory: τ=c+(σ-pw)tanφ (c is the cohesion , σ is the normal stress , pw is the pore water pressure , φ is the internal friction angle of soil ) , combined with grain size analysis , interior strength test , penetration test and sink test ,we systematically studied the effects of scaling parameters of the heterogeneous soil on the intensity parameter and permeability coefficient. In addition, the characteristics of soil failure and the evolution features of pore pressure and the relationship between the soil failure and pore pressure pore variation have been revealed in this paper. After determination of the distribution of c and φ and the temporal and spatial variation of pw, we analyzed the change characteristics of the shearing strength, thus revealed the mechanism of the source soil slope debris flow activities. There are some conclusions as follows:(1) The scale of natural soil parameters (μ, Dc) obeys Weibull distribution: f(x;λ,k)=(k/λ)(x/λ)k-1exp(-(x/λ)k), and (λ, k) exponentially decrease with the increase of slop α: (λ,k)=(aλ,ak)exp((b λ,b k)α) (2) Cohesion(c) and internal friction angle(φ) of soil have the power function relation with μ and Dc respectively: φ=AφDc-β, c=Acμa; and c~Weibull(λμaAc,kμ/a), φ~Weibull(λDcβAφ,kDc/β).So we can get the distribution of τf:τf~Weibull(λ,k) . Therefore, the scaling distribution of the heterogeneous soil determines the strength distribution of the soil.(3) Permeability coefficient K and the scale parameters with logarithmic relationship between μ, K decreases with the increase of μ, this shows that the permeability of soil mainly depends on fine particles, and randomness.The internal soil permeability cause pore pressure random fluctuation, the randomness of random pore pressure fluctuation causes non-uniform distribution of shear strength, prompting the non-uniform deformation of slope body and random destruction. The entire slope activity characterized by random collapse, which could be a reason for non-stationary surge of debris flow. 

Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/18862
Collection山地灾害与地表过程重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
苟万春. 泥石流源地土体力学性质的时空变化[D]. 北京. 中国科学院大学,2016.
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