Deformation properties of sand and gravel were evaluated by cyclic loading (CL) triaxial tests and monotonic loading (ML) triaxial compression tests using small and large triaxial apparatuses. The results were compared with those from other testing methods. The specimens had non-lubricated regular ends. Two types of local gages set on the lateral surface of specimen measured local axial and radial strains. A load cell was located inside the triaxial cell. For a strain range from about 0.0001 % to about 1 %, axial strains measured at the specimen cap in the both ML and CL triaxial tests and damping in the CL triaxial tests tend to be much larger than those measured locally due to bedding errors at the top and bottom ends of specimen. Stiffness values from static CL tests (i.e., very low frequency CL tests) and resonant-column tests (i.e., very high frequency CL tests) were nearly the same, showing that the deformation properties during CL at strains of 0.0001∼ 0.1 % can be obtained only by static CL tests. Stiffness values at strains less than about 0.001 % were practically the same among static ML and CL tests and dynamic CL tests, and between triaxial and torsional shear tests, whereas the dependency of stiffness on strain level is different among them.
The modelling of non-linear stifaffess, based on elastic characteristic moduli for stiff geomaterials, is proposed, on the basis of the results of a large number of triaxial compression tests on sedimentary soft rocks, tuff, weathered granite, cement-treated soils, densely compacted gravels and sands. Axial strains from less than 0·001% to about 1% were measured by using a local gauge, while elastic Young's moduli E sbp e were obtained by applying a series of small unload/reload cycles of axial stress during each monotonic loading test. Strain increments less than about 0·001% were nearly recoverable and strain-rate-independent. For sedimentary soft rocks and cement-treated soils, the elastic Young's moduli E e from laboratory tests using high-quality undisturbed samples were very similar to the equivalent values obtained from field seismic surveys. The dependence of E e on stress state is summarized, and the effects of geomaterial type are analysed. The non-linearity during shear deformation is regarded as being caused by damage to the elastic deformation properties and the occurrence of plastic strains. The effects of cementation and structuration on elastic deformation properties are discussed. A method to estimate the tangent Young's modulus E sub tan /sub of a given geomaterial at a given stress state from the E e value evaluated by field seismic surveys and the non-linear tangent stifaffess model is proposed. L'article prisente une mod6lisation de la rigidité non linéaire basée sur les modules d'élasticité de matériaux rigides, qui repose sur les résultats d'un grand nombre d'essais de compression triaxiale sur des ruches tendres sédimentaires, du tuf, du granit désagrégé, des sols traités au ciment, des graviers fortement tassés et des sables. Un extensomètre local a permis de me-surer des contraintes axiales allant de moins de 0,001% a 1% environ, tandis qu'une série de cycles de décharge/recharge de contraintes axiales pendant chaque essai de charge monotone a permis d'obtenir des modules d'élasticité E e de Young. Les écarts de contrainte de moins de 0,001% étaient presque récupérables et ne dé- pendaient pas du taux de contrainte. Dans le cas des ruches tendres sédimentaires et des sols traités au ciment, les essais de laboratoire sur des échantillons non perturbés de grande qualité ont produit des modules d'élasticité E sub e /sub trés semblables aux valeurs correspondantes fournies par les relevés sismiques sur le terrain. Ľarticle résume la façon dont ľélasticité E e dépend de ľétat de contrainte et analyse les effets du type de matériau. La modélisation suppose que la nonlinéarité du cisaillement est causée par la détérioration de ľéasticité et ľapparition de déformations plastiques. Ľarticle examine les effets de la cimentation et de la structuration sur les propriétés des matériaux. Enfin, il propose une méthode qui permet d'estimer le module tangent de Young E sub tan /sub d'un matériau donné à un état de contrainte donné, à partir de la valeur E e évaluée à ľaide des levés sismiques sur le terrain et du module de rigidité tangentielle non linéaire.
Four types of ground improvement by cement-treatment were used for the Trans-Tokyo Bay Highway project, which is now under way. In the first two methods, either a slurry mixture of sand, cement and sea water with some clay or a mixture of sand and cement in a rather dry state is produced in a vessel. The ‘slurry’ mixture was placed underwater using tremmie pipes, to construct fill embankments. Anti-segregation chemical adhesive was added to the ‘dry’ mixture immediately before placing underwater by using a special large diameter chute. In the other two methods, existing soft clay deposits were mixed in situ to considerable depths with cement slurry having either a high or a low cement content. The strength and deformation characteristics of undisturbed samples were obtained from test fills, and full-scale fill embankments constructed using cement-treated sand and existing soft clay deposits improved by mixing in situ with cement slurry. They were tested by an advanced triaxial testing method. Axial strains for a range less than 0·001% to about 1% were measured locally. The elastic stiffness obtained from triaxial tests using the least disturbed samples was comparable with that from field seismic surveys. Strength and stiffness of these cement-treated soils are similar to those of typical natural sedimentary soft rocks.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.