Observation and Numerical Simulation of Debris Flow Induced by Deep-Seated Rapid Landslide

Uchida, Tatsuo; Nishiguchi, Yuki; Matsumoto, Naoki; Sakurai, Wataru

doi:10.1007/978-3-319-53485-5_47

Cited by 3 publications

(4 citation statements)

References 8 publications

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“…We don't have any information about number of debris flow surges in Koslanda. However a number of disaster reports in Japan showed several debris flow surges occurred in a single event [e.g., Nishiguchi et al, 2011 ;Uchida et al, 2017]. From these evidences and results of the simulation, in Koslanda, multi debris flow surges might occur and the flow path of later debris flow surge might be affected by the topographic change due to deposition of the first debris flow surge, However, by calculation using simulation software, it was confirmed that we could estimate to some extent that it was not able to be estimated only by field survey.…”

Section: Resultsmentioning

confidence: 99%

“…In this disaster, it is thought that fluidized landslide sediment became debris flow. Previous studies showed that runout processes, such as travel distance of debris flow, erosion and deposition patterns, of landslide incurred debris flow has been described by a debris flow simulation [e.g., Egashira et al, 1998 ;Nishiguchi et al, 2011 ;Uchida et al, 2017]. We tried to describe the debris flow processes by using the one-dimensional debris flow numerical simulation program, Kanako-LS.…”

Section: Strategy Of Numerical Simulationmentioning

confidence: 99%

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Disaster Report of Koslanda Landslide in Sri Lanka on October 29, 2014

Handa

Hara

Okawara

et al. 2019

IJECE

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The Sri Lankan annual rainfall pattern is greatly influenced by the two monsoon seasons in the year, and it is divided into four periods. From December to February (the northeast monsoon period : Maha), a monsoon blows from the northeast and brings rain to the east side of the island. From March to April (the inter-monsoon period), showers and thunderstorms occur frequently around the southwestern area with the northing of the equatorial depression. From May to September (the southwestern monsoon period : Yala), there is rainfall on an average of 1,000-3,500 mm per year in the southwestern part. The central highlands also have almost the same amount of rainfall caused by monsoon. From October to November (the inter-monsoon period), there is rain throughout the island by outbreak of a cyclone. Under the influence of such a climate, sediment disasters occur in an average on approximately 50 places per year on the mountainous area in Sri Lanka (from data of National Building Research Organisation : NBRO) On 29 th October, 2014, a landslide disaster occurred in Koslanda, Badulla District, Uva Province (Fig. 1), central part of the Sri Lanka. Koslanda is located in the south end mountainous area on the central part of Sri Lanka (c.f. Situation Report of Disaster Management Centre (2016)). In Koslanda, there is a wet season from December to February under the influence of the northeast monsoon. Sediment disasters such as landslides and debris flows mostly occur during this period. Three of the authors (Mr. Handa, Mr. Hara and Mr. Okawara) were dispatched to Sri Lanka for "Technical Cooperation for Landslide Mitigation Project", and conducted an aerial survey with Mr. Shimano : JICA Sri Lanka Office and officers of Disaster Management Centre (DMC) and NBRO, Ministry of Disaster

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Section: Resultsmentioning

confidence: 99%

Section: Strategy Of Numerical Simulationmentioning

confidence: 99%

Disaster Report of Koslanda Landslide in Sri Lanka on October 29, 2014

Handa

Hara

Okawara

et al. 2019

IJECE

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“…where P is the Rouse number, w 0 is the settling velocity (cm), κ is the von Kármán constant (0.41), u * is the friction velocity (= √ gRI ), R is the hydraulic radius (m), I is the energy gradient, d is the particle size (cm), ν is the coefficient of kinematic viscosity (cm 2 s −1 ), and s is the weight per unit volume of sediment in water (= ρ s ρ −1 f − 1). The Rouse number determining the threshold condition of suspension in debris flow (ranging from 0.116 to 0.813) is smaller than the threshold of suspended sediment in fluvial channels due to the shading effect by boulders inside of the flow (Nishiguchi, 2014;Sakai et al, 2019). By assuming that R was the average flow height of monitored surges (1.07 m; Table 3), I was the local channel gradient (= sin 16 • ), ρ s = 2650 (kg m −3 ), ρ f = 1000 (kg m −3 ), and ν = 0.01 (cm 2 s −1 ), the particle sizes that provide P = 0.11 and 0.813 were 0.07 and 3.0 cm, respectively.…”

Section: Pore Water Pressure In Debris Flowmentioning

confidence: 91%

Field monitoring of pore water pressure in fully and partly saturated debris flows at Ohya landslide scar, Japan

Oya,

Imaizumi,

Takayama

2024

Earth Surf. Dynam.

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Abstract. The characteristics of debris flows (e.g., mobility, sediment concentration, erosion, and deposition of sediment) are dependent on the pore water pressure in the flows. Therefore, understanding the magnitude of pore water pressure in debris flows is essential for improving debris flow mitigation measures. Notably, the pore water pressure in a partly saturated flow, which contains an unsaturated layer in its upper part, has not been previously understood due to a lack of data. The monitoring performed in Ohya landslide scar, central Japan, allowed us to obtain the data on the pore water pressure in fully and partly saturated flows during four debris flow events. In some partly and fully saturated debris flows, the pore water pressure at the channel bed exceeded the hydrostatic pressure of clean water. The depth gradient of the pore water pressure in the lower part of the flow, monitored using water pressure sensors at multiple depths, was generally higher than the depth-averaged gradient of the pore water pressure from the channel bed to the surface of the flow. The low gradient of the pore water pressure in the upper part of partly saturated debris flows may be affected by the low hydrostatic pressure due to unsaturation of the flow. Bagnold number, Savage number, and friction number indicated that frictional force dominated in the partly saturated debris flows. Excess pore water pressure was observed in the lower part of partly saturated surges. The excess pore water pressure may have been generated by the contraction of interstitial water and have been maintained due to low hydraulic diffusivity in debris flows. The pore water pressure at the channel bed of fully saturated flow was generally similar to the hydrostatic pressure of clean water, while some saturated surges portrayed higher pore water pressure than the hydrostatic pressure. The travel distance of debris flows, investigated by the structure-from-motion technique using uncrewed aerial vehicle (UAV-SfM) and the monitoring of time-lapse cameras, was long during a rainfall event with high intensity even though the pore water pressure in the flow was not significantly high. We conclude that the excess pore water pressure is present in many debris flow surges and an important mechanism in debris flow surge behaviors.

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“…Numerical simulation is a novel approach for simulating landslides, and numerous scholars have employed this method to conduct landslide simulation experiments and compare the results with on-site tests [11][12][13]. Arbanas [14] utilized the strength reduction method to perform a numerical analysis on slopes, aiming to determine the shape of the fracture zone.…”

Section: Introductionmentioning

confidence: 99%

Modeling Rainfall Impact on Slope Stability: Computational Insights into Displacement and Stress Dynamics

Zong,

Zhang,

Liu

et al. 2024

Water

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The susceptibility of loess slopes to collapses, landslides, and sinkholes is a global concern. Rainfall is a key factor exacerbating these issues and affecting slope stability. In regions experiencing significant infrastructure and urban growth, understanding and mitigating rainfall effects on loess landslides is crucial. ADINA numerical software 9 was utilized to explore rain-induced erosion’s influence on landslide dynamics. The simulations were based on local rainfall trends. The rainfall intensities examined were as follows: 200 mm/day, 300 mm/day, and 400 mm/day. The results indicate a pronounced impact of rainfall intensity on both the movement and stress levels within the slope. Higher rainfall intensities lead to increased movement and a wider stress impact area at the base of the slope. It was observed that surface movement is minimal at the slope crest but increases towards the bottom, with the greatest movement seen at the slope’s base.

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Observation and Numerical Simulation of Debris Flow Induced by Deep-Seated Rapid Landslide

Cited by 3 publications

References 8 publications

Disaster Report of Koslanda Landslide in Sri Lanka on October 29, 2014

Disaster Report of Koslanda Landslide in Sri Lanka on October 29, 2014

Field monitoring of pore water pressure in fully and partly saturated debris flows at Ohya landslide scar, Japan

Modeling Rainfall Impact on Slope Stability: Computational Insights into Displacement and Stress Dynamics

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