Fundamental parameters for the stiffness and strength control of artificially cemented sand - A. Viana da Fonseca; Nilo Cesar Consoli; Rodrigo Caberlon Cruz; Karla Salvagni Heineck
The treatment of soils with cement is an attractive technique when the project requires improvement of the local soil for the construction of subgrades for rail tracks, as a support layer for shallow foundations and to prevent sand liquefaction. As reported by Consoli et al. in 2007, a unique dosage methodology has been established based on rational criteria where the voids/cement ratio plays a
fundamental role in the assessment of the target unconfined compressive strength. The present study broadened the research carried out by Consoli et al. in 2007 through quantifying quantifies the influence of voids/cement ratio on the initial shear...
Seismic cross-hole tomography in modeling ISC’2 experimental site - J. M. Carvalho; A. Viana da Fonseca; F. Almeida
The extensive in-situ investigation and characterization of ISC’2 experimental site, located on the campus of the Faculty of Engineering of the University of Porto (FEUP), comprised a geological reconnaissance of the area as well as the application of several geophysical and geotechnical surface and borehole methods, namely seismic P- and S-wave seismic refraction, conventional and tomographic cross-hole, high resolution SH-wave shallow reflection, geoelectrical resistivity imaging, penetration tests and pressure-dilatometer tests. In parallel, a laboratory testing program was carried out on undisturbed samples, including triaxial tests with bender elements and resonant column tests. Broadly, the site is geologically formed by an...
Bottom Ash as a geomaterial: influence of particle morphology on the behavior of granular materials - António Joaquim Pereira Viana da Fonseca; Cristiana Ferreira
Previous studies of mechanical properties of solid residue byproducts such as coal bottom ash have been restricted to small and intermediate shear strains of approximately 0.1-20%, due to the limitations of the standard equipment used (e.g. triaxial and direct shear tests) and to confining pressures up to around 1.5 MPa. The objective of the present research was to study the behavior of coal bottom ash sampled in southern Brazil, ranging from very small to very large shear strains, as well as to high isotropic pressures, to determine its complete behavior. Comparisons are made with results from a granular soil with...
Structural anisotropy by static compaction
Induced anisotropy can be applied to soils in different ways, in natural or in laboratory conditions. The aim of this work was to study the effect of load compaction in a specific remoulded residual soil from granite, especially in terms of its effect on the critical state behaviour and isotropic compression. For that purpose, isotropic compression tests and triaxial compression tests were performed up to high pressures in specimens compacted in two different ways: by moist tamping or by multi-layer heavy static compaction imposed by a load frame. The results indicated that isotropic consolidation to high pressures can minimize the...
A Framework Interpreting Bender Element Tests, Combining Time-Domain and Frequency-Domain Methods - António Joaquim Pereira Viana da Fonseca; Cristiana Ferreira; Martin Fahey
Bender element (BE) testing is a powerful and increasingly common laboratory technique for determining the shear S-wave velocity
of geomaterials. There are several advantages of BE testing, but there is no standard developed for the testing procedures or for the interpretation
of the results. This leads to high degree of uncertainty and subjectivity in the interpretation. In this paper, the authors review the most common
methods for the interpretation of BE tests, discuss some important technical requirements to minimize errors, and propose a practical framework for
BE testing, based on the comparison of different interpretation techniques in order to obtain the most reliable value...