The 3rd Badong International Geohazards Symposium (BIGS2021)

48 / 2021-11-14 23:00:32

The non-darcian flow seepage law in slip zone of Huangtupo landslide

permeability experiments; hydraulic conductivity; pore size distribution; FEG-SEM; seepage

In the reservoir area, the extensive spatial distribution of the slip zone makes the soil of the sliding zone experience different hydraulic gradient with the rise and fall of the water level. Therefore, under different hydraulic gradients, whether there is a certain law of seepage in slip zone needs to be further explored. The main objective of this study is to explore the seepage law of the soil in the  Huangtupo landslide zone. We conducted constant-head permeability experiments under 13 hydraulic gradients on the remodeled samples of 5 dry densities, and obtained the threshold hydraulic gradient (i₀), the critical hydraulic gradient (i_cr,) and the non-Darcy seepage law of the seepage gradient and hydraulic conductivity (Ks). The results show that with the increase of density, the i₀ has two obvious stages, and the i_cr tends to be stable. Furthermore, The mercury intrusion experiment (MIP) indicates that the change in permeability coefficient is closely related to the pore size distribution (PSD) of the sample. As the structure becomes denser, the pores of 0.01-1um increase, and the pores of 1um-400um decrease. Although the experiments show that the permeability of the sliding zone soil is low, the FEG-SEM scanning results show that the internal structure of the sliding zone soil has changed from that before seepage, and seepage has a certain influence on the change of the structure. The different density of slip zone soil is affected by seepage to different degrees, which is the reason for the anisotropy of the spatial structure of slip zone soil.