241 research outputs found
Centrifuge modelling of the effects of root geometry on transpiration-induced suction and stability of vegetated slopes
Experimental study on the coefficient of restitution of grain against block interfaces for natural and engineered materials
The coefficient of restitution (COR) is an important input parameter in the numerical
simulation of granular flows, as it governs the travel distance, the lateral spreading and the
design of barriers. In this study, a new custom-built micro-mechanical impact loading
apparatus is presented along with impact experiments on engineered and natural materials.
The COR and energy loss of various grains and base block combinations are studied,
including fairly regular shaped Leighton Buzzard sand (LBS) grains as a natural soil and
granite/rubber as base blocks, apart from the use of engineered materials for the grains
(chrome steel balls, glass balls) and blocks (stainless steel, brass). The repeatability of the
new micro-mechanical impact loading apparatus was checked by impacting chrome steel
balls on stainless steel block. In all the test combinations, the higher and lower values of the
COR are found for granite block (ranging between 0.75-0.95) and rubber block (ranging
between 0.37-0.44) combinations, respectively. For the tested grain-block combinations,
lower values of COR were observed for impacts between materials of low values of
composite Young’s modulus. However, within the narrow range of composite surface
roughness of the tested grain-block interfaces no particular trend was observed in the COR
values. Compared to glass balls and chrome steel balls, greater scatter in the COR values is
observed for natural sand grains. This is due to the variation of the elastic and morphological
characteristics among individual LBS grains
Correlating hydrologic reinforcement of vegetated soil with plant traits during establishment of woody perennials
Research on dynamic creep strain and settlement prediction under the subway vibration loading
Wave Propagation and Elasticity in Granular Soils:A Numerical Approach for a Micromechanical Perspective
Coriolis-induced instabilities in centrifuge modeling of granular flow
Granular flows are typically studied in laboratory flumes based on common similarity scaling, which create stress fields that only roughly approximate field conditions. The geotechnical centrifuge produces stress conditions that are closer to those observed in the field, but steady conditions can be hardly achieved. Moreover, secondary effects induced by the apparent Coriolis acceleration, which can either dilate or compress the flow, often obscure scaling. This work aims at studying a set of numerical experiments where the effects of the Coriolis acceleration are measured and analyzed. Three flow states are observed: dense, dilute, and unstable. It is found that flows generated under the influence of dilative Coriolis accelerations are likely to become unstable. Nevertheless, a steady dense flow can still be obtained if a large centrifuge is used. A parametric group is proposed to predict the insurgence of instabilities; this parameter can guide experimental designs and could help to avoid damage to the experimental apparatus and model instrumentation
Effects of root dehydration on biomechanical properties of woody roots of <i>Ulex europaeus</i>
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