路基膨胀土胀缩等级的模糊评判

Fuzzy judgment about the grade of shrink and expansion for the expansive soil in the subgrade

膨胀土胀缩等级评判是膨胀土地区工程建设的重要工作。本文在分析了现有膨胀土胀缩等级评判方法与标准的基础上,提出了模糊评判模型,涉及到的评判指标包括三项间接反映土的胀缩性能指标,液限、塑性指数Ip 、缩限ws;四项直接相关指标,自由膨胀率Fs,膨胀率Pc,50 kPa 压力下的膨胀率ep50 、胀缩总率eps。特殊情况下允许减少若干评判指标,但间接指标不得少于二项,直接指标不得少于二项,在缺乏间接指标时,直接指标不得少于三项。根据理论分析和大量实测资料建立了每个指标的权重。评判模型已编写了实用的计算机软件,经计算分析和工程检验。

The swell shrink grade judgment of expansive soil is an important work for engineering construction in the expansive soil area. Based on the analysis of the existing swell shrink grade judgment methods and standards, this paper presents a fuzzy judgment model, including three performance indexes indirectly reflecting the expansion and shrink of soil such as liquid limit, plasticity index I p and shrink limit, and four direct relative indexes such as free expansion ratio F s, swell shrink ratio P c, swell shrink ratio e p50 under the pressure of 50 kPa and swell shrink total ratio e ps . The number of judgment indexes can be reduced under special condition, but that of indirect indexes should not be less than two, or that of direct indexes should not be less than three in shortage of indircet indexes. According to the theoretical analysis and experimental data, the weight of each index is established. The useful computer software of the judgment model has been programmed, and the method in the paper is proved credible through the calculation analysis and engineering test.