摘要
本文在回顾了滤层保砂性设计的几种方法后,提出了广级配砂砾滤层保砂性的设计计算式。式中对滤料和被保护土除仍用D_(15)和d_(85)作为特征粒径外,还考虑了两者不均匀系数的作用。在采用不同的安全系数F_s时,该计算式除适用于保护广级配的砂砾(F_s=1.5)、低、无塑性的黄土(F_s=3)和粉砂(F_s=4.5)之外,在加倍取用安全系数时,还适用于“砂俘走”型或欠密实砂砾,及施工条件恶劣或过薄的滤层。本文的设计方法不仅与14组室内试验结果比较吻合,而且与80座工程共140组反滤层运行资料的分析结果也相当一致。
After reviewing a few design methods of sand gravel filters, a new design method of filter using broad graded materials is proposed in the paper. In the formula D_(15) and d_(85) are still used as control grain size, the writer also considered the effect of non-uniform coefficient of soils. Using various safety coefficients (F_s) the formula is suited not only to broad graded sand gravel(F_s=1.5)and low plastic loess (F_s=3) and silty sand (F_s=4.5),but also is suited to suffusion or loose sand gravel and bad construction conditions in the use of double safety coefficient. The design method not only agrees relatively with 14 sets laboratory test results, but also agrees relatively with 140 sets of 80 projects analyrsis results from field operation condition.
