Study Of Interbedded Slope Moisture-Heat Coupling Behavior And Slope Stability In Extreme Climates

Landslide is a common nature disaster, with the occurrence frequency of global climate warming and extreme weather, number of landslide is increasing, scholars already had great acheivements in study landslide. Interbedded soil is distributed broadly in Guangxi province due to different depositional time. The soil properties between each layers are unlike, that makes interbedded slope different from homogeneous slope whether in sensitivity to extreme climate or stability under heavy rainfall condition. However, there are not enough research achievements on the project. Therefore it is quite significant to work on it.In this paper, achievements are laid out below.Firstly, datas of extreme climate occurrence frequency of Nanning city that appears in the last 30 years are performed statistical and mainly study on extreme heat、drought and precipitation.Secondly, temperature and humidity field of typical Nanning clay and fine sand interbedded slope are analyzed by the method of numerical simulation considering soil moisture-heat coupling theory. There comes to the conclusions about slope soil moisture-heat coupling behavior and temperature-humidity filed changing law under different combination of extreme climates. Results show that comparing to deep soil, the temperature-humidity field of soil surface is easily effected by dramatic climate change. A long time climate like arid have great effect on deep soil. The soil temperature field is changing after different rainfall intensity. To the middle of the slope, the vol. water content of the deep soil will increase during the evaporation. The reason is that the pore water will permeate downward during the evaporation time. This phenomenon will disappear in arid climate.Thirdly, Slope factor of safety is various under different combination of climates. Rainstorm has the greatest impact on the slope stability, and the slope factor of safety is increasing apparently under evaporation. In short term high temperature evaporation, interbedded slope is more stabilize than homogeneous slope. But in long term evaporation, homogeneous slope is safer.Then,4 different factors were carried out to analyze their effects on the slope seepage and stability under extreme precipitation condition. It turns out that the early the peak of rainfall intensity appears the slope become more instability in the first beginning. Slope stability is less affected by different rainfall patterns in the later period. The middle layer of poor permeability mudstone is working as water-resisting layer. The thicker the middle layer is, less water would infiltrate into the inner slope. And the soaking and softening affection to the slope surface layer of siltstone are more significant. The existence of slope surface cracks lower the slope factor of safety, location of the most dangerous slip surface is inside the crack zone. The smaller the fissure distance is, the slope is more instable in the first beginning of precipitation. The slope safety of factor changes less in the later period of precipitation. Rainfall infiltration has less effect on the soil pore water pressure of the mudstone and siltstone interbed slope. Safety of factor is decreasing with the longer precipitation time and thicker of the middle siltstone layer, but it decreases far more less than the siltstone and mudstone interbed slope.Finally, the effects of prestressed lattice beam and anchor structure to slope stability are discussed. Results show that lattice beam and anchor structure is effective in slope displacement constraint and improving slope factor of safety.