Laboratory experiments on rainfall-induced flowslide from pore pressure and moisture content measurements

Abstract

Abstract. During or immediately after rainfall many slope failures have been observed. The slope failure occurred due to rainfall infiltration that rapidly increase the pore pressure and trigger the slope failure. Numerous studies have been conducted to investigate the rainfall-induced slope failure, but the mechanism of slope failure is still not well clarified. To investigate mechanism of rainfall-induced slope failure laboratory experiments have been conducted in flume. The slope was prepared with sandy soil in flume with constant inclination of 45°, because most of rainfall-induced slope failure occurred in sandy soil and on steep slope. The hydrological parameters such as pore pressure and moisture content were measured with piezometers and advanced Imko TDRs respectively. The slope failure occurred due to increase in moisture content and rise in pore pressure. During the flowslide type of slope failure the sudden increase in pore pressure was observed. The higher moisture content and pore pressure was at the toe of the slope. The pore pressure was higher at the toe of the slope and smaller at the upper part of the slope. After the saturation the run-off was observed at the toe of the slope that erodes the toe and forming the gullies from toe to upper part of the slope. In the case antecedent moisture conditions the moisture content and the pore pressure increased quickly and producing the surface runoff at the horizontal part of the slope. The slope having less density suffer from flowslide type of the failure, however in dense slope no major failure was occurred even at higher rainfall intensity. The antecedent moisture accompanied with high rainfall intensity also not favors the initiation of flowslide in case of dense slope. The flowslide type of failure can be avoided by controlling the density of soil slope. Knowing such parameters that controls the large mass movement helpful in developing the early warning system for flowslide type of failure.

Analysis of Geotechnical-Assisted 2-D Electrical Resistivity Tomography Monitoring of Slope Instability in Residual Soil of Weathered Granitic Basement

“…Changes in water conditions and slope geometry are the main factors that induce slope instability (Tang et al, 2018) in the presence of discontinuities such as faults, fractures, and beddings which are precursors to landslide (Chalupa et al, 2018). Since, the world is experiencing heavy and extreme rainfall events because of global climate change (Kirschbaum et al, 2020), the continuous precipitation during typhoon increases slope instability around mountains which has led to severe mudflows and landslide events (Baum et al, 2010;Pradhan and Lee, 2010;Epada et al, 2012;Jeong et al, 2014;Chien et al, 2015;Hakro and Harahap, 2015;Baharuddin et al, 2016;Sidle and Bogaard, 2016;Jeong et al, 2017;Kumar and Rathee, 2017;Soto et al, 2017;Tomás et al, 2018;Kirschbaum et al, 2020). A majority of these landslides have caused a considerable loss of lives and properties (Choi and Cheung, 2013;Askarinejad et al, 2018).…”

Geomorphological characteristics of slope failures in northeast Viti Levu island, Fiji, triggered by Tropical Cyclone Winston in February 2016

“…). While granular soils tend to respond quickly to intense rainfall of short duration (Au ; Hakro & Harahap ), the typically clay‐dominated Fiji soils have been particularly sensitive to prolonged rainfall (Crozier et al . ; Bronders ; Greenbaum et al .…”

Response of Groundwater and Soil Displacement at Slope of Electric Transmission Tower Due to Rainfall Events

“…Moreover, the is none of the research prove that water table rise significantly and trigger shallow failure and most of the landslide occurs above the groundwater table that usually one to three meters from the surface. [12]. Hence, for these study areas, the possibility of landslide occurrence due to an increment of the groundwater table was not expected.…”

“…For fine-grained soil such as at all studied locations, slope failure might not occur during or immediately after prolonged rainfall. However, the possibility of landslide occurrence might be some time after the end of rainfall, as explained in [12].…”