Abstract
Evaluation of slope stability under water level fluctuations is an important topic in the Three Gorges Reservoir (TGR) in China. However, most of the previous studies regarded slope soil as isotropic material, or only considered the influence of anisotropy ratio (kr = kx/ky) but ignored the anisotropy direction (α). Meanwhile, the pore pressure–stress coupling was rarely considered in the previous numerical simulations. In the present study, the SIGMA/W and SLOPE/W modules in Geo-studio are utilized to carry out the numerical simulation of Caipo slope under the drawdown of the reservoir water level, and the anisotropy ratio (kr) as well as the anisotropy direction (α) of two kinds of soils (clay and sand) are included. Results show that the anisotropy ratio kr and anisotropy direction α decrease the infiltration capacity of the soil, which increases the infiltration line hysteretic elevation (ILHE) as well as maximum horizontal displacement (MHD), and reduces the minimum safety factor (MSF). The slope toe firstly fails with the drawdown of water level. The influence of reservoir water level drop on seepage, deformation, and stability of the sand slope is less than that of the clay slope. For the sandy soil slope, it is not only necessary to consider the influence of kr, but also the influence of α. For the soil slope, we can only consider α in order to simplify calculation.
Highlights
With the rapid development of China’s economy, large amounts of hydropower stations have been built, which provides a great guarantee for China’s clean energy production, and the ThreeGorges Project is the typical one
This section carries out the discussion based on the classification of sandy soil and clay soil slopes
The infiltration line, x-displacement, and safety factors of the 25th day with kr = 10 are displayed to illustrate the influence of anisotropy direction α on seepage, deformation, and stability of the Caipo slope, and those of the 25th day with α = 45◦ are displayed to show the impact of the anisotropy ratio kr
Summary
With the rapid development of China’s economy, large amounts of hydropower stations have been built, which provides a great guarantee for China’s clean energy production, and the ThreeGorges Project is the typical one. Since the completion of the Three Gorges Reservoir (TGR) in 2003, landslide disasters in the reservoir area have occurred continuously under the cycle of reservoir water level fluctuations, as is shown in Figure 1a [1,2]. The TGR began to impound water in June 2003, and the elevation of water level was 135 m, which was maintained until October 2006, and the number of landslides was the largest in this period. Water 2020, 12, 201 reservoir water level fluctuated between 145 m and 165 m, and the number of landslides in this period. Water 2020, 11, x FOR PEER REVIEW was more concentrated. From October 2008 to December 2015, the reservoir water level stabilized. October water level fluctuated between 145 m and. 175reservoir m, and the number of landslides decreased significantly landslides in this was moreoccasionally.
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