The Paper describes the findings of plane strain unit cell tests on Leighton Buzzard sand with and without inclusions of aluminium foil, aluminium mesh and a non-woven melt bonded hetrofilament fabric. The results are analysed in terms of boundary stresses and strains and also internal deformation patterns. These data indicate that reinforced earth is a limiting condition where ideally inextensible materials are included in soils to strengthen them and inhibit both internal and boundary deformations. Another limiting condition is where ideally highly extensible materials are included. The composite system is in this case termed ‘plysoil’ as it exhibits some strengthening but more importantly has greater extensibility and smaller losses of post peak strength compared to sand alone or reinforced earth. This alteration to the stress-strain behaviour of the sand is shown to be a consequence of alterations to the internal deformations induced by the presence of the extensible inclusions. From this understanding of the mechanisms operating in reinforced earth and plysoil systems, the optimum conditions for their employment have been clarified. L'étude décrit les découvertes faites à partir d'essais de compression en cellule à déformation plane sur le sable de Leighton Buzzard avec et sans inclusions de feuille d'aluminium, de maille d'aluminium et d'une matière non-tissée à filaments hétérogènes qui est liée à chaud. Les résultats sont analysés sous forme de contraintes et de déformations limites et aussi de déformations internes. Ces données indiquent que la terre armée est une condition limite là où des matières idéalement inextensibles sont inclues dans des sols afin de les renforcer et d'empêcher les déformations internes et limites. Une autre condition limite est le cas où des matières idéalement extensibles sont indues. Le système composé est dans ce cas appelé sol manié parce qu'il montre une certaine résistance plus importante, a une extensibilité plus considérable et de plus faibles pertes de résistance maximum que le sable seul ou la terre armée. Ce changement du comportement contrainte-déformation du sable est la conséquence du changement des déformations internes produites par la présence des inclusions extensibles. A partir de cette compréhension des mécanismes se produisant dans les systèmes de terre armée et de sol manié, les conditions optimums pour leur emploi ont été clarifiées.

The deformation characteristics of sand and other granular materials under hydrostatic compression are studied in the conventional triaxial apparatus using 4 × 4 in. (10 × 10 cm) specimens. Modifications have been made for measuring small axial strains and free end platens were used. The errors in testing have been estimated and their effect was evaluated. Different kinds of granular materials were tested to study the effect of the physical properties of the material on its deformational behavior.The results showed that the total deformation of a mass of sand subjected to a hydrostatic compression is generally not recoverable, and can be divided into elastic (recoverable) and sliding (irrecoverable) components. It has also been found out that for a dense specimen of sand most of the total deformation is recoverable, since the sliding component of deformation represents only a small fraction of the total deformation. The results also showed that for the very dense specimen axial and radial strains were nearly equal which implies that the material behaves isotropically. On the other hand for a loose specimen the sliding component of deformation becomes large and thus the total deformation of the specimen cannot be considered completely elastic. Furthermore axial and radial strains of the loose specimen were not equal.

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