Undrained dynamic-loading ring-shear apparatus and its application to landslide dynamics

Sassa, Kyoji; Fukuoka, Hiroshi; Wang, Gonghui; Ishikawa, Naohide

doi:10.1007/s10346-003-0004-y

Cited by 258 publications

(140 citation statements)

References 13 publications

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“…As a result, the shear resistance may drastically decrease, leading to slope instability. Sassa et al (2004) noted that the process of grain crashing that occurs in weathered pumice and tuŠ during strong shaking may be an additional factor that would determine the high velocity and long run-out distance of the landslides.…”

Section: Discussion On the Causes Of Catastrophic Landslidesmentioning

confidence: 99%

Geotechnical Aspects of the Sumatra Earthquake of September 30, 2009, Indonesia

Gratchev

Irsyam

Towhata

et al. 2011

Soils and Foundations

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This paper reports and discusses the results of aˆeld survey conducted by a joint scientiˆc group from Japan and Indonesia to assess the geotechnical aspects of the Sumatra earthquake (Mw＝7.6) of September 30, 2009. The studied area included the Padang and Pariaman cities, where a number of buildings collapsed as a result of strong shaking, and a mountainous part of the Pariaman district, a place where massive landslides buried several villages, claiming more than 400 human lives. The main objective of the survey was to investigate the causes and mechanisms of catastrophic landslides; however, other geotechnical problems such as lateral spread and liquefaction were also addressed. Field observations indicated that the catastrophic landslides occurred on relatively gentle slopes, then mobilized into debris ‰ows, and traveled several hundred meters from their points of origin. The failure surfaces developed along the boundary of highly weathered pumice tuŠ with more intact and less weathered bedrock. Data from a portable cone penetration test showed that the sliding material was rather weak, having SPT N-values in the range of 5-10. The results of theˆeld survey suggested that the main cause of slope instability was high pore-water pressures that generated in the soil mass during the earthquake.

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Section: Discussion On the Causes Of Catastrophic Landslidesmentioning

confidence: 99%

Geotechnical Aspects of the Sumatra Earthquake of September 30, 2009, Indonesia

Gratchev

Irsyam

Towhata

et al. 2011

Soils and Foundations

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show abstract

“…Because of such rapid dynamic loading, the saturated slope failed under undrained conditions. With reference to dynamic-loading ring-shear tests on saturated volcanoclastic deposits, Sassa et al (2004) demonstrated that only a slight additional shear stress was required to cause failure under undrained conditions. Owing to the difficulty in quantifying all the variable requirements in this case-history, soil stability back-analyses should lead to a better prediction of the required dynamic load for slope failure.…”

Section: Discussionmentioning

confidence: 99%

“…Liquefaction takes place in soils with loose meta-stable structure so long as grain crushing and the resulting volume reduction takes place under the given overburden pressure. Sassa et al (2004) described a dynamic-loading ring-shear apparatus that can simulate the formation of shear zones including long and rapid shear displacements that occur in highvelocity or earthquake-induced landslides, under undrained loading conditions. Iverson et al (1997) indicated that most landslides that mobilize to form debris flows are triggered by increased pore-water pressures associated with rainfall, snowmelt, or groundwater inflow from adjacent areas.…”

Section: Introductionmentioning

confidence: 99%

Rockfall-induced impact force causing a debris flow on a volcanoclastic soil slope: a case study in southern Italy

Budetta

2010

Nat. Hazards Earth Syst. Sci.

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Abstract. On 10 January 2003, a rockfall of approximately 10 m 3 affected a cliff some 25 m high located along the northern slopes of Mt. St. Angelo (Nocera Inferiore, province of Salerno) in the southern Italian region of Campania. The impact of boulders on the lower sector of the slope, along which detrital-pyroclastic soils outcrop, triggered a small channelled debris flow of about 500 m 3 . Fortunately, no damage nor victims resulted from the landslide. Several marks of the impacts were observed at the cliff toe and outside the collapsed area, and the volumes of some fallen boulders were subsequently measured. By means of in-situ surveys, it was possible to reconstruct the cliff's geo-structural layout in detail. A rockfall back-analysis was subsequently performed along seven critical profiles of the entire slope (surface area of about 4000 m 2 ). The results of this numerical modelling using the lumped-mass method were then used to map the kinetic iso-energy curves. In the triggering area of the debris flow, for a falling boulder of 1 m 3 , the mean kinetic energy was estimated at 120 kJ, this value being equivalent to an impact force, on an inclined surface, of some 800 kN. After landing, due to the locally high slope gradient (about 45 • ), and low angle of trajectory at impact (about 23 • ), some boulders slid down the slope as far as the endpoints. The maximum depth of penetration into the ground by a sliding block was estimated at about 16 cm. Very likely, owing to the high impact force of boulders on the saturated soil slope outcropping at the cliff base, the debris flow was triggered under undrained loading conditions. Initial failure was characterized by a translational slide involving a limited, almost elliptical area where the pyroclastic cover shows greater thickness in comparison with the surrounding areas.

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“…The continuously varying shear area leads to inconstant and heterogeneous normal stress in soil (Dai et al 1998). The ring shear method, therefore, is adopted to measure the shear strength of sliding zone soil as a large shear displacement is allowed while the shear area and the normal stress can be maintained constant during the test (American Society for Testing and Materials 1964; Sassa et al 2004;Yang et al 2001). To estimate the residual shear strength of the landslide slip surface.…”

Section: Methodsmentioning

confidence: 99%

“…In the last decade, the role that sliding zone soil, as well as its liquefaction, plays in the development and occurrence of large landslides have been increasingly stressed (Wang et al 2002(Wang et al , 2007Hu et al 2009;Sassa et al 2004;Zhang et al 2011a;Rozos et al 2011Rozos et al , 2013Mohamed et al 2013). More importantly, similarly to that observed by Hu et al (2009) during ring shear tests on soil of the Yigong long-distance landslide, obvious liquefaction of shear strips are observed in the sample S01.…”

Section: Liquefaction Of the Sliding Zone Soilmentioning

confidence: 99%

Reactivation mechanism of ancient giant landslides in the tectonically active zone: a case study in Southwest China

et al. 2015

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The reactivation mechanism and stability of ancient landslides are the major concerns in the tectonically active zone. A detailed case study has been conducted to examine the reactivation mechanism of ancient landslides in Southwest China by investigating the reactivation process, shear strength and stability. Field investigation suggests that the reactivation of ancient giant slides, such as the Luosiwan slide, is attributed to the cumulative effect of adverse geological, structural condition and intensive artificial processes. However, long-term observation has shown that the ancient giant landslides usually remain stable in the remote area in spite of such adverse conditions. Ring shear tests also indicate high peak shear strength of the sliding zone soils. However, the shear strength decreases significantly once displacement occurs at the toe of giant landslide due to engineering construction. The construction process could be considered as the critical triggering factor for the reactivation of ancient giant landslide, which exerts sudden changes in the forces acting on the slope. Both longterm adverse geological evolution and sudden change in the strength lead to the reactivation of giant landslide. This study also suggests that liquefaction plays an important role in the failure behavior of reactivated ancient landslide. An effective drainage system has to be set up during engineering construction so as to reduce the probability of reactivation of ancient landslides.

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Undrained dynamic-loading ring-shear apparatus and its application to landslide dynamics

Cited by 258 publications

References 13 publications

Geotechnical Aspects of the Sumatra Earthquake of September 30, 2009, Indonesia

Geotechnical Aspects of the Sumatra Earthquake of September 30, 2009, Indonesia

Rockfall-induced impact force causing a debris flow on a volcanoclastic soil slope: a case study in southern Italy

Reactivation mechanism of ancient giant landslides in the tectonically active zone: a case study in Southwest China

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