1,721,114 research outputs found
Evaluation of the response of a geosynthetics reinforced structure to a debris flow impact
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Residual strength parameters from a slope instability.
Full text linkThe study attempts to determine the in situ shear strength parameters of a stiff clay from a back analys1s of a well documented landslide. The relatively small extension of the instability, as well as the homogeneity of the clay formation and the defined slip surface, allows a consistent evaluation of shear strength parameters. The study is also supported by ring shear tests, and microscopic analysis performed on undisturbed thin sections, by means of scanning electron microscopy. The results of back analysis are in good agreement with laboratory tests and microscopy observations
A simple method to evaluate the pullout resistance of extruded geogrids embedded in a compacted granular soil
No full textPullout tests are necessary in order to study the interaction behaviour between soil and geosynthetics in the anchorage zone; hence, the resulting properties have direct implications on the design of reinforced soil structures. Several experimental studies showed the influence of different parameters (reinforcement stiffness, geometry and length, applied vertical effective stress, and geotechnical properties of soil) on the peak and on residual pullout resistance. On the basis of the results of the tests carried out by Moraci and Recalcati [2005. Factors affecting the pullout behaviour of extruded geogrids embedded in a compacted granular soil. Geotextiles and Geomembranes, submitted for publication], a new theoretical method was developed to determine the peak and the residual pullout resistance of extruded geogrids embedded in a compacted granular soil. The method is capable of evaluating both the bearing and the frictional components of pullout resistance, taking into account the reinforcement extensibility and geometry as well as the non-linearity of the failure envelope of backfill soil. The comparison between theoretical and experimental results was favourable, thus confirming the suitability of the proposed approach. © Elsevier Ltd. All rights reserved
Corrigendum to "A simple method to evaluate the pullout resistance of extruded geogrids embedded in a compacted granular soil". [Geotextiles and Geomembranes 24 (2006) 116-128] (DOI:10.1016/j.geotexmem.2005.11.001)
No full textChanges in natural clay microstructure due to laboratory weathering
No full textPart of the research to characterize the soils involved in shallow landslides is described in the paper. The studied landslides were the slide-flows occurred in September 2000 in the Jonian side of Calabria (Italy). In particular, the results of micro-structural investigations performed on natural clay specimens taken from samples near detachment zones are shown. The comparison of the results between the investigation on intact and artificially weathered specimens showed the wide micro-structural changes due to weathering cycle
The design of geotextile filters for granular soils
No full textThe use of geotextile filters is very common in geotechnical and in environmental engineering. In these structures the flow conditions (steady and unsteady flow, parallel or normal flow to filter, high or low hydraulic gradients) and the boundary conditions (vertical effective stresses, continuity of contact between the filter and the base soil) can be very different. In all applications the functions of filter are to prevent the movement of fine particles of base soil and to avoid the development of excessive pore water pressure on interface between base soil and filter. The main filter functions are retaining the base soil: pore size distribution and filtration opening size must be lower than fixed limits (retention criterion); being more permeable than base soil: pore size distribution and filtration opening size must be higher than fixed limits (permeability criterion). The available design criteria are often the result of theoretical and experimental analyses carried out in laboratory under experimental conditions different respect to the field conditions. Moreover, the design criteria do not consider the different flow conditions and the boundary conditions. In this paper, on the base of the current knowledge and trends in geotextile filter design and research a new procedure for the design of geotextile filter is show
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