地裂缝区黄土和充填土持水曲线的测试与计算

Measurement and Calculation of Water Retention Curves of Loess and Filling About Ground Fissure

摘要:

为评价地裂缝区域黄土和充填土持水性能差异及微观机理，实测了两者持水曲线，根据微观结构计算了持水曲线和进气值，根据孔隙分布分析了实测持水曲线的特征.研究结果表明,实测的黄土持水曲线在低吸力段位于充填土之上并在高吸力段接近重合，曲线均存在滞回性；基于孔隙分布计算得到的持水曲线与实测曲线形状相似，并能反映一定的滞后现象；实测和Schubert理论所得进气值分别接近于本文公式所得进气值的下限和上限，而由计算持水曲线间接所得进气值位于上、下限之间；黄土大孔隙体积较充填土多而微小孔隙分布相近是两者持水曲线产生差异的原因；双孔隙结构是导致持水曲线中间存在平缓段的微观原因.

Abstract:

In order to evaluate the water retention capacity of loess and filling about ground fissure and investigate the soil water retention curves (SWRCs) from the micro point of view, the SWRCs of the two soils were measured, and the SWRCs and the air entry values of two soils were calculated based on micro structure. In addition, the characteristic of SWRCs were analyzed from pore size distribution (PSD). The research results indicate that the SWRC of loess lies above that of the filling at low suction range and almost coincides with it at high suction range, and both curves show hysteresis phenomena. The calculated SWRCs based on PSD are similar to the measured in shape and also show hysteresis characteristic. For each soil, the air entry value of the measured SWRC and that calculated by Schubert’s theory are respectively close to the lower limit and the upper limit of calculated value by the proposed formula based on particle arrangement while the air entry value of the calculated SWRC lie between the lower limit and the upper limit. The main reason for the difference of SWRCs between the loess and the filling is that the loess has more macro pores and similar distribution of small pores compared with the filling. The middle flat section in SWRC is founded to be caused by the dual porosity structure.