Stability of loess high-fill slope based on monitored soil moisture changes

Abstract

This paper aims to assess the influence of moisture content changes during rainfall on the stability of loess high-fill slopes by taking a loess high-fill slope in Lanzhou City as an example. First, according to the moisture content monitoring data collected from a slope online monitoring system, direct shear tests were performed on soil samples of different moisture content to determine the relationship between the shear strength parameters and moisture content. Next, a coupled hydro-mechanical model with soil shear strength related to moisture content was established and used to analyze 16 working conditions with various rainfall intensities and durations for two cases: shear strength parameters from the site exploration report and those from this study. Finally, the results from the two cases were compared regarding the changes in stresses and displacements after rainfall infiltration to analyze the influence of moisture content on the stability of loess high-fill slopes. The conclusions are as follows: (1) Segmental relationship equations of cohesion and angle of internal friction were established for loess with various moisture content. (2) Under the conditions of different rainfall intensities, significant differences were observed in the trends of slope stress and displacement changes. (3) The slope displacement occurred in the shallow soil layer within about 12.5 m from the slope top, and the plastic strain concentrated in the soil layer within about 6 m from the slope top. (4) The results of slope stability analyses based on moisture content monitoring data are more in line with the observed.