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

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.

Key words:soil water retention curve; loess; ground fissure; suction; pore size distribution