钙质砂的渗透特性及其影响因素探讨

发布时间：2018-05-15 19:57

本文选题：钙质砂 + 双环渗透试验　；参考：《岩土力学》2017年10期

【摘要】：钙质砂在沉积过程中大多保持着原生生物骨架中的细小孔隙,多孔隙且含内孔隙、形状不规则、强度低易破碎、颗粒棱角度高、会胶结等特殊性质。其工程力学性质较一般陆相、海相沉积物有较大的差异,尤其多孔性和形状高度不规则性致使其渗透性与其他岩土介质差异明显。针对钙质砂的渗透特性开展现场多组双环渗透试验,分析密实度和颗粒级配对钙质砂渗透性的影响。现场渗透试验显示,钙质砂中的渗流速度先缓慢增大再趋于稳定,最后稳定在小幅度波动范围内;钙质砂的渗透系数K与不均匀系数C_u呈负相关关系;由于颗粒分析曲线上小于有效粒径d_(10)的曲线拐点多出现在小于某粒径土重累计百分含量为4%对应的粒径d_4附近,以新变量d_4与限制粒径d_(60)之比d_4/d_(60)分析其与钙质砂渗透性的关系,并经指数函数拟合得一定干密度ρ_d和压实度δ下的钙质砂的渗透系数关系式K=4.75e~(2d_4/d_(60)~n/lgC_u/δ)或K=4.74e~(3.374d_4/d_(60)~n/lgC_u/ρ_d),根据C_u≤5、5C_u≤10、10C_u≤20和C_u≥20的取值,n分别取值2、5、4、3。
[Abstract]:In the process of deposition, the calcareous sand mostly maintains small pores in the primary biological skeleton, many pores and inner pores, irregular shape, low strength and low breakage, high angle of grain prism, and cementation, etc. its engineering mechanical properties are more different than those of general continental facies and marine sediments, especially the heterogeneity and the irregular shape of the shape. The permeability of the calcareous sand has been tested by multi group double ring permeability test, and the effect of density and particle size on the permeability of calcareous sand is analyzed. The seepage test in the field shows that the seepage velocity in the calcareous sand increases slowly first and then tends to stability, and finally is stable in the range of small amplitude fluctuation. The permeability coefficient K of calcareous sand is negatively correlated with the inhomogeneity coefficient C_u; the curve inflexion of less than the effective particle size d_ (10) appears near the particle size d_4 which is less than the cumulative percentage of a particle size of 4%, and the ratio of the new variable d_4 to the restricted particle diameter d_ (60) is analyzed by d_4/d_ (60), and the permeability of calcareous sand is analyzed. The relationship is fitted by exponential function, and the coefficient of permeability coefficient K=4.75e~ (2d_4/d_ (60) ~n/lgC_u/ delta) or K=4.74e~ (3.374d_4/d_ (60) ~n/lgC_u/ Rho _d) under certain dry density p _d and degree of compaction is obtained, and the values are obtained respectively according to the values of C_u < < 5,5C_u < 10,10C_u < 20 > and C_u > 20.

【作者单位】：中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室;广西大学土木建筑工程学院;广西大学海洋学院;
【基金】：国家自然科学基金面上项目(No.41572304,No.41372313) 中科院科技先导专项A类子课题(No.XDA13010301)~~
【分类号】：TU441

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