共检索到 4

Rainfall-induced debris slides are a major geological hazard in the Himalayan region, where slopes often comprise heterogeneous debris-a complex mixture of rock and soil. The complex nature makes traditional soil or rock testing methods inadequate for assessing such debris's engineering behaviour and failure mechanisms. Alternatively, reduced-scale flume experiments may aid in understanding the failure process of debris slopes. Here, we present findings from reduced-scale laboratory flume experiments performed under varying slope angles (ranging from shallow to steep), initial volumetric water contents (ranging from dry to wet), and rainfall intensities (ranging from light to heavy) using debris materials with a median grain size (D50) 20.7 mm sampled from a rainfall-induced debris slide site in the Himalayas. Hydrological variables, including volumetric water content and matric suction, were monitored using sensors, while slope displacement was tracked indirectly, and rainfall was monitored using rain gauges. The entire failure process was captured via video recording, and index and shear strength tests were performed to characterize the debris material. Our results reveal that the failure of debris slopes is not driven by sudden increases in pore water pressure but by the loss of unsaturated shear strength due to reduced matric suction and a decreased frictional strength from reduced particle contact between grains during rainfall. We also find that the saturation of debris slope by rainfall was quick irrespective of the slope angles and initial moisture contents, revealing the proneness of debris slopes to rainfall-induced failures. These findings provide critical insights into the stability of debris materials and have important implications for improving risk assessment and mitigation strategies for rainfall-induced debris slides in the Himalayas and similar regions worldwide.

期刊论文 2025-06-05 DOI: 10.1016/j.enggeo.2025.108051 ISSN: 0013-7952

Fine grains migration is a primary cause of landslides and debris flows. This study investigates the effect of fine-grain migration on slope failure through flume experiments, focusing on the spatiotemporal characteristics and mechanisms of slope stability. A series of artificial rainfall flume experiments with varying rainfall intensities and slopes were conducted using soil samples collected from Wei Jia Gully. The experiments monitored pore-water pressure, grain migration, and failure sequences. Grain-size distribution parameters (mu and Dc) were analyzed to understand the migration path and accumulation of fine grains. The experiments reveal that fine-grain migration significantly alters soil structure, leading to random blockage and interconnection of internal pore channels. These changes result in fluctuating pore-water pressure distributions and uneven fine-grain accumulation, critical factors in slope stability. Slope failures occur randomly and intermittently, influenced by fine-grain content in runoff and resulting pore-water pressure variations. This study highlights that fine-grain migration plays a vital role in slope stability, with significant implications for predicting and mitigating slope failures. The stochastic nature of fine-grain migration and its impact on soil properties should be incorporated into predictive models to enhance their accuracy and reliability.

期刊论文 2024-10-05 DOI: 10.1007/s11629-024-8833-3 ISSN: 1672-6316

IntroductionsA large-scale flume experiment was performed to evaluate the mechanism of landslide occurrence due to rainfall using weathered granite sand. The dimensions of the flume were 9 m (length), 1 m (width), and 1 m (depth). The weathered granite sand from the actual landslide site at Da Nang City, Vietnam was used. The pore water pressure was measured by a pore-water pressure transducer at two depths (middle and bottom) to determine the process of rainwater infiltration into the soil. The surface deformation was measured with extensometers at three positions of the slope. The deformation of the entire slope was determined by the 160 cylindrical-shaped makers evenly spaced in the slope and three cameras.ResultsThe results showed that the rainfall infiltrated into the slope process, increasing from negative pore water pressure to approximately 0. The maximum shear strain contour has been plotted in total and in time increments. The shear band was detected from the time increments maximum shear strain contour. The localization in the shear band formed just before failure.ConclusionsTo the best of our knowledge, this is the largest scale laboratory test ever conducted to calculate the shear band. Moreover, it was found that the failure occurred when the sand was in an unsaturated phase. Failure does not seem to depend on the increase in pore water pressure but on the maximum shear strain. This feature can be used to explain the phenomenon of landslides that occur even when the groundwater level does not increase but large deformation occurs.

期刊论文 2024-07-02 DOI: 10.1186/s40677-024-00280-x

Slope revegetation by seeding works with herbaceous plants is widely employed to prevent road embankment from erosion damage. The Percentage of Vegetational Cover (PVC) is used as an indicator for the quality evaluation of the seeding works. However, the PVC is usually measured manually through visual inspection, and the measurement results of the same subject might not be constant. In the present study, RGB image analysis is applied to objectively measure the PVC to overcome this situation. Then, laboratory flume experiments are conducted to investigate the capability of the PVC obtained by RGB image analysis to predict the decrease of sediment erosion against concentrated flow. Two herbaceous plant species, Centipede Grass and White Clover, are employed in the experiments. The findings of the experiments are as follows: Declining trends of the sediment erosion are observed as the PVC increases or plant growth period becomes longer, and the trends are more correlated with the PVC with RGB image analysis than with plant growth period. The results indicate that RGB image analysis can be a useful and inexpensive tool for inspection of the seeding works with herbaceous plants.

期刊论文 2024-01-01 DOI: 10.1007/978-981-99-9223-2_3 ISSN: 2366-2557
  • 首页
  • 1
  • 末页
  • 跳转
当前展示1-4条  共4条,1页