Centrifuge Model Studies of the Seismic Response of Reinforced Soil Slopes

Nova-Roessig, Lili; Sitar, Nicholas

doi:10.1061/(asce)1090-0241(2006)132:3(388)

Cited by 88 publications

(27 citation statements)

References 13 publications

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“…However, neither of these materials is a perfect analogue to the mechanical behaviour of real roots (see Liang et al (2014)) and, to the best of the present authors' knowledge, testing under fully dynamic ground motions representative of real earthquake shaking has not previously been conducted. Again, this is in contrast to other potential methods of seismic slope reinforcement which have been investigated using dynamic centrifuge testing, including for geosynthetics (Nova-Roessig & Sitar, 2006) and piles (Al-Defae & Knappett, 2014).…”

Section: Introductionmentioning

confidence: 97%

Modelling the seismic performance of rooted slopes from individual root–soil interaction to global slope behaviour

Liang¹,

Knappett²,

Duckett³

2015

Géotechnique

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Modelling the seismic performance of rooted slopes from individual root-soil interaction to global slope behaviour T. LIANG Ã , J. A. KNAPPETT Ã and N. DUCKETT † Many natural and man-made slopes are planted with vegetation, and it is known that this can increase the stability of slopes under static conditions. There is anecdotal evidence that vegetated slopes also perform better than fallow slopes during earthquakes. However, the study of the dynamic behaviour of slopes planted with species having dichotomous ('woody') roots is relatively rare owing to the extreme expense and difficulty involved in conducting full-scale dynamic testing on shrubs and trees. In this paper, dynamic centrifuge testing and supporting numerical modelling have been conducted to study this problem. In the centrifuge modelling, ABS plastic rods are used to simulate repeatably the mechanical properties of real roots. The numerical modelling work consisted of two parts. First, a computationally-efficient beam-on-non-linear-Winkler-foundation (BNWF) model using existing p-y formulations from piling engineering was employed to produce a macro-element describing the individual root and soil interaction both pre-and post-failure. By adding contributions from the different root analogues of different diameters, smeared continuum properties were derived that could be included in a fully dynamic, plane-strain continuum, finite-element model in a straightforward way. The BNWF approach was validated against large direct shear tests having stress conditions simulating those in the centrifuge at different potential slip plane depths. The conversion to smeared properties for global time-history analysis of the slope was validated by comparing the continuum finite-element results with the centrifuge test data in terms of both the dynamic response and permanent deformations at the crest, and these demonstrated good agreement. Owing to the simplicity of the BNWF approach and its ability to consider variable root geometries and properties, along with variation of soil properties with depth, it is suggested that the validated approach described will be useful in linking individual root-soil interaction characteristics (root strength and stiffness, diameter variation, root spacing and so on) to global slope behaviour.KEYWORDS: centrifuge modelling; earthquakes; finite-element modelling; numerical modelling; slopes; vegetation INTRODUCTION Vegetation (grasses, shrubs and trees), as an effective and environmentally friendly approach to improving slope stability, improves slope stability mainly through direct mechanical reinforcement of soil and by modifying groundwater conditions by means of evapotranspiration. The net effect of both of these mechanisms is an increase in shear strength within a defined zone around the roots, although only the mechanical effect is present at all times; the hydrological effects potentially disappear following heavy rain. In terms of the direct mechanical effect, many studies have been performed to quantify the increase in soil ...

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Section: Introductionmentioning

confidence: 97%

Modelling the seismic performance of rooted slopes from individual root–soil interaction to global slope behaviour

Liang¹,

Knappett²,

Duckett³

2015

Géotechnique

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“…Physical modelling using reduced scale models is often preferred by the researchers because of several advantages like reasonably large size models, facility to embed instrumentation and ability to carry out tests under controlled conditions. Researchers have successfully used shaking table tests [1][2][3][4] and centrifuge tests [5,6] to understand the influence of various parameters on the seismic performance of reinforced soil slopes or walls. The test results generally showed that the permanent displacements increased with increasing input motion amplitude and decreased with increasing reinforcement stiffness, density, and decreasing slope angle.…”

Section: Introductionmentioning

confidence: 99%

Seismic Response of Soil Slopes in Shaking Table Tests: Effect of Type and Quantity of Reinforcement

Srilatha

Latha

Puttappa³

2016

Int. J. of Geosynth. and Ground Eng.

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To study the effect of reinforcement type and quantity on the response of model slopes in this study, a series of shaking table tests were carried out on model slopes reinforced with different quantities of geotextile and geogrid. Model slopes were constructed to an angle of 45°using poorly graded sand. Acceleration of base shaking and shaking frequency were varied in different tests. The response of model soil slopes is compared in terms of the acceleration amplifications and horizontal displacements of the slope measured at different elevations. Results from these model tests revealed that the acceleration amplifications were slightly lesser in case of geogrid reinforced slopes because of higher interfacial friction of cohesionless soil with the geogrid. Acceleration amplifications were not affected by varying the quantity of reinforcement. However, horizontal displacements reduced drastically with the inclusion of reinforcement. Though the difference was not substantial, geotextile reinforced slopes were more effective in reducing the deformations compared to geogrid reinforced slopes. With the increase in the quantity of reinforcement, deformations decreased linearly, until reinforcement saturation occurred, beyond which the rate of decrease of deformations was less.

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“…Zornberg et al [15] used centrifuge modeling as a tool for analyzing the behavior of reinforced soil slopes. NovaRoessig and Sitar [16] studied the dynamic behaviour of soil slopes reinforced with geosynthetics and metal grids, with focus on the failure mechanism and amount of deformations under seismic loading. Katz and Aharonov [17] investigated the type of slope failure and frequency magnitude relations of landslides.…”

Section: Introductionmentioning

confidence: 99%

Distinct element method analyses of idealized bonded-granulate cut slope

Jiang

Murakami

2012

Granular Matter

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This paper presents a numerical study of idealized bonded-granulate cut slope subject to sudden strength reduction. A 2-D Distinct Element Method (DEM) has been used to carry out a simulation of full-process slope failure with focus on very-rapid and extremely-rapid landslide process. The numerical results show that during the landslide process: (1) the soil moves either in a rather random/chaotic way (diffuse failure) or in different curved shear bands (localized failure). The soil close to slope surface moves along downward slope while the soil close to the slope toe moves significantly in the horizontal direction. The landslide experiences very rapid flow most of the time, with its maximum velocity increaseing obviously with time at first to its peak value, then decreasing gradually to zero. (2) The soil close to slope undergo a repeated loading and unloading process, and an evident rotation of principal stresses. Their stress state may arrive slightly over the peak strength envelope as a result of extremely rapid flow. (3) There is little grain-size effect for the grains at low velocity, but an evident grain-size effect for the grains at high velocity, with large-size grains tending to move fast. (4) The post-failure inclination is much smaller than the peak/residual internal friction angle of the material.

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Centrifuge Model Studies of the Seismic Response of Reinforced Soil Slopes

Cited by 88 publications

References 13 publications

Modelling the seismic performance of rooted slopes from individual root–soil interaction to global slope behaviour

Modelling the seismic performance of rooted slopes from individual root–soil interaction to global slope behaviour

Seismic Response of Soil Slopes in Shaking Table Tests: Effect of Type and Quantity of Reinforcement

Distinct element method analyses of idealized bonded-granulate cut slope

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