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黄土是中国西部常见的一种天然建筑材料,受形成环境影响,其物理力学性质在空间上表现出显著的差异性,研究典型黄土的物理力学性质,对区域工程建设具有一定借鉴意义。以陕西泾阳南塬典型斜坡中Q_2黄土为研究对象,通过激光粒度分析、土常规试验、X射线衍射试验、渗透试验、三轴试验及环剪试验等方法,系统地研究了泾阳南塬Q_2黄土的物理力学特性。研究结果表明:泾阳南塬Q_2黄土具有一定的大孔隙结构,粒组成分以细粒组为主;天然含水率、密度及孔隙比随埋深呈规律性变化;黄土中原生矿物及次生矿物含量分别占到50%和47%;塑限为(15.4±1.2)%,液限为(26.8±0.7)%;渗透性较低,具有各向异性,有效渗透系数为3.455×10~(-4) cm/s;含水率对黄土的应力-应变关系、抗剪强度参数及破坏模式具有显著影响,塑限可视为黄土脆性与塑性变形的界限值;残余强度受剪切速率及法向应力影响较大,残余强度参数随剪切速率的增大而降低,与法向应力无关。
Loess is a kind of natural building material which is common in western China. Due to its influence on environment, the physical and mechanical properties of the loess show significant differences in space. Studying the physical and mechanical properties of typical loess has certain reference value for regional engineering construction. Taking Q_2 loess in typical slopes of Jingyang South Plateau in Shaanxi Province as the research object, the effects of grain size, soil routine test, X-ray diffraction test, infiltration test, triaxial test and ring shear test on the Q_2 loess in Jingyang South Plateau The physical and mechanical properties. The results show that: the Q_2 loess in Jingyang South Plateau has some macropore structure, and the grain composition is dominated by fine-grained group; the natural water content, density and porosity ratio change regularly with the burial depth; the primary and secondary minerals (15.4 ± 1.2)% and the liquid limit of (26.8 ± 0.7)% respectively. The permeability is low and anisotropic with the effective permeability coefficient of 3.455 × 10 ~ (- 4) cm / s. Moisture content has a significant effect on the stress-strain relationship, shear strength parameters and failure mode of loess. Plastic limit can be regarded as the limit value of loess brittleness and plastic deformation. The residual strength is affected by the shear rate and normal direction The influence of stress is larger, and the residual strength parameter decreases with the increase of shear rate, which has nothing to do with the normal stress.