Newmark sliding block model for pile-reinforced slopes under earthquake loading

Aldefae, Asad H.; Knappett, Jonathan

doi:10.1016/j.soildyn.2015.04.013

Cited by 24 publications

(12 citation statements)

References 21 publications

(37 reference statements)

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“…This can be interpreted as a result of the rapid mobilisation of root-soil interaction due to the initial soil slip under dynamic loading. Al-Defae & Knappett (2015) have demonstrated that, for the case of large vertical piles reinforcing slopes to significant depths, the full lateral restraint of the piles is mobilised within 2% of the pile diameter; applying this analogously to the root analogues here would suggest very rapid mobilisation due to the small root diameters. After the first two motions, relatively smaller reductions (in total 14%) were observed, which indicates that the additional resistive force of the root is largely constant after the initial rapid increase.…”

Section: (B)mentioning

confidence: 74%

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: (B)mentioning

confidence: 74%

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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“…Here, non-associative flow was modelled by adjusting the value of ' = ' mob used in the analyses from the actual value for the true non-associative behaviour to an equivalent associative value   as suggested in [20] and previously used for other seismic limit analysis problems (e.g. [21], [22]), given by:…”

Section: Influence Of Non-associativitymentioning

confidence: 99%

“…When a ground motion is large enough to push the mobilised yield surface to the capping yield surface the soil will dilate to the maximum (capping) condition and any further increase in ground acceleration and seismically induced shear stress will not further change the shape of yield surface. Compared to recent previous sliding block models ([13], [22]) which considered strong ground motions with peak accelerations large enough to easily exceed the peak strength, the use of ' mob here extends the range of applicability to smaller ground motions, a feature which will be useful in the later validation against centrifuge data.…”

Section: Mobilised Friction Angle Accounting For Pre-peak Deformationsmentioning

confidence: 99%

Newmark sliding block model for predicting the seismic performance of vegetated slopes

Liang¹,

Knappett²

2017

Soil Dynamics and Earthquake Engineering

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“…Kumar A. [9], Luo C. [10] and Al-Defae A. H. [11] perform a study on seismic performance of pile foundation, finding that the bridge seismic performance not only touches upon bridge structure but it relates to boundary condition. Since dynamic is a key matter for bridge seismic research, the river bed scour weakens seismic capacity of pile foundation and changes structural dynamic performance as well, consequently further swaying seismic response.…”

Section: Introductionmentioning

confidence: 99%

An Evaluation on Bridge Bearing Capacity under Scour and Re-occurrence of Strong Earthquake

2019

Teh. vjesn.

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Plagued by frequent calamities, Bridge No.3 encountered magnitude-8 earthquake on May 12, 2008 and several years later its pile foundation was intensively scoured. The smallest scour depth was 4.5 meters and the largest scour depth was 9.2 meters. Considering intense scour and re-occurrence of strong earthquake, the Chinese existing standard and seismic response analysis are used to study bearing capacity and seismic performance of pier and pile foundation of Bridge No.3 before and after scour. It is proved by calculation that the bridge is stable before scour and can hardly bear strong earthquake and intense scour after scour, therefore consolidation is required. The study result may serve as an important reference for the bridge affected by serious scour and strong earthquake.

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Newmark sliding block model for pile-reinforced slopes under earthquake loading

Cited by 24 publications

References 21 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

Newmark sliding block model for predicting the seismic performance of vegetated slopes

An Evaluation on Bridge Bearing Capacity under Scour and Re-occurrence of Strong Earthquake

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