Journal ArticleDOI
The general and congruent effects of structure in natural soils and weak rocks
S. Leroueil,P. R. Vaughan +1 more
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In this article, the engineering properties of naturally occurring sedimentary and residual deposits which are usually treated in geotechnical engineering as ‘soils’ are reviewed, and it is shown that usually they have characteristics due to bonded structure which are similar to those of porous weak rock.Abstract:
The engineering properties of naturally occurring sedimentary and residual deposits which are usually treated in geotechnical engineering as ‘soils’ are reviewed, and it is shown that usually they have characteristics due to bonded structure which are similar to those of porous weak rock. While this structure can arise from many causes, its effects follow a simple general pattern that involves stiff behaviour followed by yield. This yield can be described in a similar way to that occurring due to overconsolidation, although it is a separate phenomenon. The effects of structure are as important in determining engineering behaviour as are the effects of initial porosity and stress-history, which are the basic concepts of soil mechanics. As it can be described in a general way, it is concluded that structure and its effects should be treated as a further basic concept of equal importance. L'article passe en revue les proprietes des depots sedimentaires et residuels naturels qui sont nor-malement traites comm...read more
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A structured Cam Clay model
M D Liu,John P. Carter +1 more
TL;DR: A theoretical study of the behavior of structured soil is presented in this article, where a new model, referred to as the Structured Cam Clay model, is formulated by introducing the influence of soil structure into the model.
Journal ArticleDOI
Characterization of Cemented Sand in Triaxial Compression
Fernando Schnaid,Fernando Schnaid,Pedro Domingos Marques Prietto,Pedro Domingos Marques Prietto,Nilo Cesar Consoli,Nilo Cesar Consoli +5 more
TL;DR: In this article, an analysis of the stress-strain strength behavior of an artificially cemented sandy soil produced through the addition of portland cement was performed from the interpretation of results from unconfined compression tests, drained triaxial compression tests with local strain measurements, and scanning electron microscopy, in which the influence of both the degree of cementation and the initial mean effective stress was investigated.
Journal ArticleDOI
A constitutive model for structured soils
Michael Kavvadas,Angelo Amorosi +1 more
TL;DR: In this paper, a constitutive model for structured soils is proposed, which describes the engineering effects of structure development and degradation, such as: high intact stiffness and strength, appreciable reduction of stiffness due to de-structuring, and evolution of stress-and structure-induced anisotropy.
Journal ArticleDOI
Micro- and macro-mechanical behaviour of DEM crushable materials
TL;DR: In this article, the authors provide a micro-mechanical commentary on the macroscopic behavior observed in DEM simulations of the compression of individual crushable grains, and of triaxial tests on assemblies of both crushable and uncrushable grains.
Journal ArticleDOI
Compaction‐driven evolution of porosity and permeability in natural mudstones: An experimental study
Abstract: This paper describes a series of experiments designed to investigate the influence of lithology on the compactional loss of porosity and permeability in mudstones. Two intact samples of London Clay with clay fractions of 40% and 67% were compacted to 33 MPa effective stress. Clay fraction, permeability, porosity, pore size distribution, and specific surface area were measured and their evolution was monitored throughout the compaction process. Electron microscopy was combined with mercury porosimetry to trace the collapse of the pore structure with increasing effective stress. In both cases, porosity loss occurred primarily by the collapse of large pores. This process is more obvious in the coarser-grained sample because throughout the compaction process it has a much broader range of pore radii and a much greater mean pore radius. Consistent with the pore size distributions, the permeability of the coarser sample ranges from ∼ 10−10 m s−1 to 10−12 m s−1 while that of the finer-grained sample ranges from ∼4 × 10−12 m s−1 to 5 × 10−14 m s−1 during progressive compaction from 2 to 33 MPa. The compressibility of the finer-grained sample is greater than that of the coarser-grained sample (0.15 as opposed to 0.07). However, in both cases the compressibility is much lower than that inferred for lithologically similar samples compacted over geological timescales. The demonstration that both porosity and lithology (clay fraction) influence the permeability of mudstones should allow the development of more realistic porosity-permeability relationships which take into account lithological variations exhibited by mudstones.
References
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Journal ArticleDOI
On The Yielding of Soils
TL;DR: In this paper, Hvorslev's equation for the shear strength of clay is shown to define a surface in a space of three variables σ, e and τ. The progressive yielding of a sample defines a loading path in this space, and the paths taken by samples in differing tests can be correlated if a boundary energy correction is applied.
Journal ArticleDOI
Stress–strain–strain rate relation for the compressibility of sensitive natural clays
TL;DR: In this paper, four types of oedometer tests (constant rate of strain tests, controlled gradient tests, multiple-stage loading tests and creep tests) were carried out on a variety of Champlain sea clays.
Journal ArticleDOI
Cemented sands under static loading
TL;DR: In this paper, a test program was undertaken to define the nature of the cementation and its effect on behavior of the soils, and a total of 137 laboratory compression and tension load tests were performed on undisturbed samples of naturally and artificially prepared cemented sands.
Journal ArticleDOI
Ninth Laurits Bjerrum Memorial Lecture: "Small is beautiful"—the stiffness of soils at small strains
TL;DR: In this paper, the authors show how field measurements of displacement around foundations and excavations combined with numerical analysis and recent developments in laboratory techniques can be used to estimate the displacement of foundations.
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