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生活垃圾由于组成成分的多样性及分层填埋,其孔隙呈不均匀分布,并且水平向多于竖向。填埋体中的渗流存在明显的优先流效应,各向异性显著并受上覆压力等因素影响。基于Poiseuille方程,根据上覆压力作用下生活垃圾孔隙形状、孔隙尺寸分布及孔隙排列方向分布特征,提出了基于优先流及各向异性的饱和渗流模型。揭示了新鲜生活垃圾分布变化规律,0~200 k Pa,大孔隙逐渐消失,平均孔隙直径与可排水孔隙率呈指数下降,孔隙排列角度逐渐水平向倾斜。采用新建饱和渗流模型进行分析计算,确定采用可排水孔隙率可比总孔隙率更好地模拟垃圾孔隙渗流特性。渗流由大孔隙优先流主导,0~600 k Pa内计算获得新鲜垃圾水平向饱和渗透系数变化范围为10~(-2)~10~(-5)cm/s。给出了渗流各向异性值的计算公式,渗流各向异性值大体随上覆压力增加而增大,并与初始孔隙排列角度相关;0~600 k Pa内计算得新鲜垃圾渗流各向异性值变化范围为1~10。
Due to the diversity of composition and the stratified landfill, the domestic garbage has uneven pore distribution and more horizontal than vertical. The seepage flow in landfill has obvious preferential flow effect, anisotropy is significant and affected by overburden pressure and other factors. Based on the Poiseuille equation, the saturated flow model based on the preferential flow and the anisotropy is proposed according to the pore shape, pore size distribution and pore distribution direction of the refuse under overlying pressure. The distribution of fresh household garbage was revealed. The macropores disappeared gradually when the pore size was 0 ~ 200 kPa. The average pore diameter and drainage porosity decreased exponentially, and the angle of pore arrangement was gradually inclined horizontally. The new saturated seepage model was used to analyze and calculate, and it was determined that the drainage porosity could be used to simulate the seepage characteristics of trash pores better than the total porosity. The seepage flow is dominated by the macropore preferential flow, and the horizontal saturation permeability coefficient of fresh garbage calculated from 0 to 600 kPa ranges from 10 -2 to 10 -5 cm / s. The calculation formula of seepage anisotropy value is given. The seepage anisotropy value generally increases with the increase of overburden pressure and is related to the initial pore arrangement angle. The seepage anisotropy value of fresh landfill calculated from 0 ~ 600 kPa The variation range is 1 ~ 10.