1,721,150 research outputs found
On the use of viscoplasticity to describe time-dependent behaviour of polyethylene geomembranes
No full textThe paper deals with the use of viscoplasticity to simulate the behaviour of polyethylene geomembranes for any numerical simulation
Influence of relative density and stress level on the bearing capacity of sands
No full textA finite element approach is presented to determine the bearing capacity of shallow footings on silica sand deposit
Effects of a single geosynthetic reinforcement on the mechanical behavior of a sand layer
No full textThe effects of the introduction of a single sheet of different types of geoesynthetic materials on the mechanical behavior of a sand layer are studied through precise physical model loading tests performed using circular plates resting on reinforced sand. The results of the plate tests are then used to validate a finite element approach to model the response of the reinforced granular soil below the plate. It is shown that the finite element model can reliably predict the overall behavior of reinforced soil, giving, particularly, an insight on the influence of geosynthetic reinforcement over the volumetric behavior at failure of the surrounding soil and, therefore, on the mechanical response of the composite system
USO INTEGRATO DI PROVE IN SITO PER LA CARATTERIZZAZIONE DEI TERRENI
No full textSicurezza, economia, efficienza ed affidabilità di un’opera di ingegneria geotecnica dipendono in gran parte dall’accuratezza raggiunta nella caratterizzazione dei depositi di terreno con i quali l’opera stessa interagisce. Per tale caratterizzazione sono disponibili approcci di tipo geofisico, prove geotecniche in posto e sondaggi con prove geotecniche di laboratorio. Questi approcci operano su scale diverse: i metodi geofisici sono generalmente impiegati per una caratterizzazione su larga scala, le prove in posto per la ricostruzione del profilo stratigrafico e la stima delle proprietà geomeccaniche, mentre le prove di laboratorio servono per una valutazione del comportamento meccanico in condizioni di tensione e di deformazione controllate. Dopo una breve illustrazione delle principali indagini sismiche, l’intervento discute alcuni aspetti delle prove con piezocono sismico e dilatometro sismico per la caratterizzazione geotecnica dei terreni. Infine, si dà un breve cenno alle raccomandazioni riportate nella bozza finale dell’Eurocode 7 – Geotechnical Design. Part II Ground Investigation and Testing per la conduzione e l’interpretazione delle prove con piezocono e dilatometro
Analysis of behavior of sand surrounding pile tips
No full textA finite element approach is presented to predict the behaviour of dense sand surrounding the pile tip in a fairly large stress range, from low stress levels to very high ones, where particle-breakage occurs. The approach is based on a constitutive model for sand, which is characterized by critical state type yield surfaces and by a non-linear Mohr-Coulomb failure criterion, the latter being defined on the basis of constant volume shear strength and of dilatancy. In addition, the concept of constant relative breakage surfaces, which represent families of curves characterized by constant amounts of particle-crushing, is introduced. It is shown that the model, applied to the analysis of the behaviour of the tip of non-displacement piles in sand, can be utilized to visualize and to predict the distribution of strength, dilatancy and grain-breakage in the soil surrounding the pile base
A Finite Element Approach to the Strength of Granular Soils reinforced with Geosynthetics
No full textSome aspects of an experimental and numerical research concerning the improvement of the mechanical characteristics of sand reinforced with geosynthetics are presented in the paper. In particular, the effects of the introduction of reinforcements on the volumetric behaviour of cohesionless soil are considered and analysed using the finite element method. The finite element model is also applied to the prediction of the bearing capacity of reinforced soil and the results are compared with experimental 1-g model loading tests
Characterization of the Venice lagoon silts from in-situ tests and the performance of a test embankment. Keynote Lecture
No full textTo protect the historic city of Venice against recurrent flooding, a huge project has been undertaken, involving the design and construction of movable gates located at the three lagoon inlets for controlling tidal flow. The selection of the movable gate foundations demands very extensive and low cost geotechnical characterization of the Venice lagoon soils. These are composed of a predominantly silty fraction combined with clay and/or sand forming an erratic interbedding of various types of sediments, whose basic mineralogical characteristics vary narrowly. To this end two typical test sites in the lagoon area - the Malamocco Test Site and the Treporti Test Site – were selected for the mechanical characterization of Venice soils and a site-specific calibration of the most widely used geotechnical investigation tools. The main outcome of the research carried out at the Malamocco Test Site and some preliminary results from the Treporti Test Site are here presented and discussed
A finite element analysis of the tip bearing capacity of bored piles in sand
No full textThe effect of relative density and effective stress level on the behaviour of large diameter bored piles is investigated by a finite element analysis. The elasto-plastic constitutive model adopted in this study is based on a non linear Mohr-Coulomb criterion in which the two main components of shear resistance are considered, namely the ones related to shearing at constant volume and to dilatancy
Numerical modelling of bearing capacity of shallow footings on sand
No full textThe study presents a finite element approach to model punching behaviour under a shallow circular footing on san
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