Search results for "Geotechnical engineering"
showing 10 items of 489 documents
Role of particle characteristics in the compression behaviour of gap-graded sands
2019
Abstract The compression in gap-graded mixtures of sands with combined mineralogy has been investigated in recent research, focusing on the key factors that might imply the occurrence of convergent or non-convergent paths in compression (i.e., transitional or non-transitional behaviour). From previous work, the mineralogy of a matrix composed of larger grains seems to determine the possibility of the occurrence of transitional behaviour. Hence, if there is a strong and stiff matrix made of quartz sand particles, which are either larger than or at least of similar size to the other component, then non-convergent compression paths (i.e., transitional behaviour) are likely to occur. As a furth…
Seismic behavior of structures equipped with variable friction dissipative (VFD) systems
2021
Usually, to mitigate the stresses in framed structures, different strategies are used. Among them, base isolation, viscous/friction/metallic yielding dampers and tuned mass dumpers have been widely investigated. Fluid Viscous Dampers (FVD) probably result the most diffused for the simplicity in the applications. However, these type of dampers request limited interstorey drifts to avoid dangerous effects. Further, they have an elevate cost. On the contrary, friction dampers are not so expensive but request high interstorey drifts to give a significant contribute in the dissipation of energy during an earthquake. In this paper an approach for the energy dissipation by friction, modified with …
Microstructure and shear strength evolution of a lime-treated clay for use in road construction
2020
The results of a comprehensive experimental programme are presented for assessing the long-term microstructural modifications and evaluating the effects of microstructural rearrangement on the stress–strain behaviour of a lime-treated high-plasticity clay for road embankments. The stress–strain behaviour at different lime content and curing time was investigated by means of direct shear tests; microstructural analyses were carried out combining Scanning Electron Microscope observations and Mercury Intrusion Porosimetry tests. The results show that the stress–strain behaviour of treated clay is strongly dilatant with a high peak of strength, which increases with time and lime content. Furthe…
One-dimensional compression and consolidation of shales
2016
This paper presents a comprehensive methodology for analysing the compression and consolidation behaviour of shales. An apparatus was designed to perform oedometric high-pressure tests by applying a maximum vertical total stress of 100 MPa and simultaneously controlling the pore water pressure of the specimen. An analytical method was formulated to analyse the shale consolidation behaviour, which allows information to be gathered on the coefficient of consolidation, stiffness, poroelastic properties, secondary compression and permeability of the tested material as a function of the applied stress conditions. Results obtained on Opalinus Clay shale using the developed methodology are present…
Crop Yield Estimation and Interpretability With Gaussian Processes
2021
This work introduces the use of Gaussian processes (GPs) for the estimation and understanding of crop development and yield using multisensor satellite observations and meteo- rological data. The proposed methodology combines synergistic information on canopy greenness, biomass, soil, and plant water content from optical and microwave sensors with the atmospheric variables typically measured at meteorological stations. A com- posite covariance is used in the GP model to account for varying scales, nonstationary, and nonlinear processes. The GP model reports noticeable gains in terms of accuracy with respect to other machine learning approaches for the estimation of corn, wheat, and soybean …
Analytical solution of kinematic wave time of concentration for overland flow under green-ampt infiltration
2015
In this paper the well-known kinematic wave equation for computing the time of concentration for impervious surfaces has been extended to the case of pervious hillslopes, accounting for infiltration. An analytical solution for the time of concentration for overland flow on a rectangular plane surface is derived using the kinematic wave equation under the Green-Ampt infiltration. The relative time of concentration is defined as the ratio between the time of concentration of an infiltrating plane and the soil sorptivity time scale, depending on the normalized rainfall intensity and a parameter synthesizing the soil and hillslope characteristics. It is shown that for a more complex case (corre…
Exploiting Low-Cost 3D Imagery for the Purposes of Detecting and Analyzing Pavement Distresses
2020
Road pavement conditions have significant impacts on safety, travel times, costs, and environmental effects. It is the responsibility of road agencies to ensure these conditions are kept in an acceptable state. To this end, agencies are tasked with implementing pavement management systems (PMSs) which effectively allocate resources towards maintenance and rehabilitation. These systems, however, require accurate data. Currently, most agencies rely on manual distress surveys and as a result, there is significant research into quick and low-cost pavement distress identification methods. Recent proposals have included the use of structure-from-motion techniques based on datasets from unmanned a…
Microstructural characterization of a 3D-printed soil
2022
Transversal applications of 3D-printing (or Additive Manufacturing) have been recently implemented in the field of Geomechanics. In a 3D-printing process, the printed volume is obtained from successive layering of adjacent soil filaments. In this work, the fabric of an as-printed soil has been carried out by combining Mercury Intrusion Porosimetry (MIP) tests and Scanning Electron Microscope (SEM) observations, with the aim to highlight how the particle arrangements and the orientation and shape of pores are linked to the printing operation. The microstructural analyses showed that macropores are the result of the relative position of the filaments and their initial distortion in quasi-undr…
From Laboratory Mixes Evaluation to Full Scale Test: Fatigue Behavior of Bio-Materials Recycled Asphalt Mixtures
2020
The present paper describes the full-scale accelerated test, carried out on asphalt pavements made up with bio-materials, especially designed to help reusing Reclaimed Asphalt (RA) by re-activating the aged binder. Four pavement sections were evaluated: three pavement sections with innovative bio-materials (bio-recycled asphalt mixtures), and a reference section with a conventional, high modulus asphalt mix (EME2). In this study, fatigue resistance was first evaluated in laboratory, with two-points bending test, and then at full scale under heavy traffic loading, with the IFSTTAR accelerated pavement testing facility. The evolution of bio-materials recycled asphalt mixture characteristics, …
Generalized effective stress concept for saturated active clays
2021
Experimental evidence shows that changes in pore-water chemistry can significantly affect the mechanical behavior of saturated active clays. Despite this evidence, how the chemical composition of the pore water can be considered in effective stress definition is questionable. This paper develops the concept of generalized effective stress for active clays. To this end, physicochemical studies on water–clay mineral interactions are used to clearly define the different types of ions and water present in an active clay. In particular, the presence of both movable and non-movable ions within the liquid water is highlighted. Taking this into account, thermodynamic and geochemistry principles ar…