中文摘要：

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）,

英文摘要：

In the deposition process, the calcareous sand, mostly retaining tiny pores of the protozoan skeleton, shows hierarchical porosity, irregular shape, high angular edge, low strength and fragile, cemented property of particles. Therefore calcareous sand are different from general terrestrial and marine sediments in its engineering properties especially the permeability due to the hierarchical porosity and highly-irregular shape. In this study, the double-ring permeation experiments are carried out to analyze the effect of density and particle size on the permeability of calcareous sand. Test results show that the seepage rate of calcareous sand increases gradually and then stabilizes within a range of small fluctuation. The permeability coefficient of calcareous sand is negatively correlated with the nonuniformity coefficient C_u. As the inflection points of particle-size distribution curve become smaller than effective diameter d_（10） appear near the weight-accumulative 4% percent diameter d_4 of soil, the ratio of d_4 to constrained diameter d_（60） is adopted to analyze the relationship between the dry density and the permeability of calcareous sand. An exponential function is fitted between permeability coefficient with dry density ρ_d and compaction degree δ. The fitting exponential function of the calcareous sand permeability coefficient is K=4.75e~（2d_4/d_（60）~n/lgC_u/δ）orK=4.74e~（3.374d_4/d_（60）~n/lgC_u/ρ_d）. If the values of C_u≤5, 5C_u≤10,10C_u≤20 and C_u≥20 are recommended, the corresponding values of n are 2, 5, 4, 3, respectively.