Numerical simulation of groundwater rising due to rainfall at far field in triggering landslide

Abstract

Landslide is a major issue in tropical countries. The intensive rainfall is the main triggering factor for a landslide that causes a loss in lives and properties. Landslide's triggering factors are several such as rain infiltration, earthquake, and human activities and so on. Those factors are very common. In this paper, the effect of rising of groundwater table in triggering landslide with respect to soil type, soil permeability and rain intensity in a regional scale were studied by running coupled seepage-slope analysis using SOILWORKS software. The results indicate that soil slopes with high permeability coefficient are prone to fail during rainstorm due to the high infiltration of rainwater and the quick rise of the groundwater table, which increases the pore-water pressure. The highest rain infiltration occurs during the first rainfall event and declines at the second and third rainfall due to the saturation of soil at the top layer and the development of a perched water table. It was noticed that the negative pore water pressure increased above the groundwater table and reached its max at the crest of the slope due to the absence of wetting front and the movement of voids with the advancement of the groundwater table. Both high and low rainfall intensities have the same effect on the deep groundwater table. Sandy-silt soil slope was highly affected by rainfall infiltration in comparison with Sandy-clay and Silty-clay slope due to the difference in soil suction where it rose up-60 kpa with Sandy-silt slope after 8 hours of the rainfall which allows more rainwater to infiltrate comparing to other soil slopes which rose up to-21 and-17 kpa for Sandy-clay and Silty-clay slopes respectively. The groundwater table rises above the toe level of the slope causing the factor of safety to drop from 1.312 to 0.93 at the end of the third day. The study indicates that the rainfall at far field of the slope could trigger landslide due to the rise of the groundwater table.

Groundwater suitability for irrigated agriculture in Alluvial Bengal delta plain: Areview

“…The study projected area wise annual usable and potential recharge between 183 to 1287 mm and 135 to 1910 mm, respectively. The approximations of net recharge in Bangladesh have increased from 132 mm/yr over a period from 1975 to 1980 to about 190 mm/yr for the period of 2002 to 2007 [47]. Recent past studies confirmed that the ratio of groundwater recharge and abstraction in the country gradually downfall.…”

“…Rain and floodwater are the principal sources of groundwater recharge in Bangladesh. Numbers of studies forecast that vast groundwater-fed irrigation would prolong net recharge in areas where soil properties and surface lithology are good permeable that favor recharge [6], [46], [47]. The study projected area wise annual usable and potential recharge between 183 to 1287 mm and 135 to 1910 mm, respectively.…”

Vertical Capillary Barriers and Wick Drains to Mitigate the Rain-induced Slope Failures: Numerical Analysis

“…The applied rainfall intensity, which was a moderate magnitude, was selected as 25 mm/hr (0.6 m/day). This value was chosen based on prior research studies that have documented rainfall intensities ranging from 10 mm/hr to 200 mm/hr [16], [17], [18].…”