Meso-structure evolution of the sliding zone under seepage conditions

Abstract

Periodic fluctuations of reservoir water level lead to the variations in seepage stress inside landslide bodies. Dynamic seepage pressures can lead to deterioration in the structure and strength of the slide zone, which affects the stability of the landslide. To identify the effect of seepage on the pore structure of the slip zone, the seepage tests were performed. First, a seepage test apparatus was developed and combined with CT scanning technology to obtain the meso-structure of the sliding zone under different seepage conditions. Then, the changes in the structural parameters of the slip zone soils were quantified by Avizo software. Finally, the mechanism of the meso-structural evolution of the sliding zone under seepage was analyzed. The results show that the permeability coefficient of the sliding zone decreases exponentially with time, and a higher seepage pressure will lead to a smaller permeability coefficient of the sliding zone. Statistical data show that the apparent porosity of sliding zone soil decreases from 5% to 1%. The proportion of pores with an equivalent spherical diameter of less than 80 μm increases with seepage time, while the proportion of pores with an equivalent spherical diameter greater than 80 μm decreases with seepage time. The above results indicate that the large pores in the slip zone soils are filled with small particles during the seepage.Hence, the seepage channels become elongated and curved, and the effective connectivity of the pores is weakened.

Keywords

• seepage
• sliding zone
• meso-structure
• pore
• huangtupo landslide