The failure of thick-walled hollow cylinders of isotropic rock

Hoskins, E.R.

doi:10.1016/0148-9062(69)90030-8

Cited by 67 publications

(21 citation statements)

References 15 publications

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“…As concerns the first purpose, the combination of internal pressure, external pressure and axial load allows to subject samples to truly threedimensional state of stress also called polyaxial (σ 1 > σ 2 > σ 3 > 0) and to study their mechanical behaviour under a wide variety of stress paths (Hoskins 1969;Alsayed 2002). In low permeability materials, the use of hollow cylinder samples has the advantage to reduce the drainage path compared to experiments on standard full cylinder specimens and consequently to speed up the equalisation of pore water pressures during sample resaturation and consolidation (Monfared et al 2011).…”

Section: Hollow Cylinder Testingmentioning

confidence: 99%

Hollow Cylinder Simulation Experiments of Galleries in Boom Clay Formation

2013

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The rights are held by Springer-Verlag Wien.The final publication is available at http://link.springer.com. Abstract: In the context of nuclear waste disposal in clay formations, laboratory experiments were performed to study at reduced scale the Excavation Damaged Zone (EDZ) induced by the construction of galleries in the Boom Clay formation. For this purpose, thick-walled hollow cylindrical samples were subjected (after recovery of in-situ stress conditions) to a decrease of the inner confining pressure aiming at mimicking a gallery excavation. X-Ray computed Tomography (XRCT) scans of the specimens were carried out through the testing cell before and after the mechanical unloading and allowed to quantify the displacements undergone by the clay as a result of the mechanical unloading. The deformation of the hollow cylinders and the inferred extent of the damaged zone around the central hole are found to depend on the orientation of the specimen with respect to the bedding planes and show a great similarity with in-situ observations around galleries and boreholes at Mol URL in the Boom Clay formation. In the experiments performed on samples cored parallel to the bedding, the damaged zone is not symmetrical with respect to the hole axis and extends more in the direction parallel to the bedding. So it is for the radial convergence of the hole walls which is larger in the direction parallel to bedding than in the perpendicular one. On the contrary, a test on a sample cored perpendicularly to the bedding did not show any ovalisation of the central hole after the mechanical unloading. These observations confirm the significance of the pre-existing planes of weakness (bedding planes) in Boom Clay and the need for a correct consideration of the related mechanical anisotropy.

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Section: Hollow Cylinder Testingmentioning

confidence: 99%

Hollow Cylinder Simulation Experiments of Galleries in Boom Clay Formation

2013

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“…2); this group includes the detailed results of A. N. Stavrogin [9]; 2) all other data, i.e., ~ # +l(l~ol ~I); here the most representative experimental data are those in [18,27] (Fig. 3).…”

Section: 3mentioning

confidence: 98%

“…Most real rocks cannot be regarded as ideally brittle materials: the value of a2 influences the strength standard, or else the type of stress state indicates an interrelation between the areas T, Tz2, and T23, determining the attainment of the strength limit. To construct the surface it is necessary to carry out loading by a triaxial state of stress, which is only possible in equipment of special design [18,27].…”

Section: 3mentioning

confidence: 99%

Two problems in rock mechanics arising out of the working of deep ore or coal deposits

Shemyakin¹

1975

Soviet Mining Science

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Research of the stress-strain state of extensive rock masses, including that in the neighborhood of systems of underground workings, is becoming important as deep coal and ore deposits are being opened up, deep mines being planned and constructed, and systems for mining at great depths being created.This research is being done by geophysicists, mechanical engineers, and mining engineers, both in order to refine our basic ideas on the state of stress of the earth's crust and for practical purposes associated with mining at great depths. Depths have already been reached at which the stresses in the undisturbed rock are comparable with its strength (we arbitrarily call such depths "great").At these depths such dangerous phenomena as shock bumps are more frequent and more hazardous; here we must reexamine the question of the "optimim" technology (e.g., work with continuous stowing).We can distinguish two main groups of problems in rock mechanics, the first of which involves assessing the initial state of the rock (before disturbance by human agency), estimating its stresses and principal displacements; the second involves strength calculations on the structural elements of systems of workings (development and main workings and the influence of extraction operations).

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“…1). L'éprouvette peut ainsi être chargée simultanément par une pression extérieure, une pres sion intérieure et une force axiale (HOSKINS, 1969) voire également par un gradient de température entre les parois internes et externes du tube (JOHNSON et GANGI, 1980), etc. En ce qui concerne la géométrie des tubes épais, et notamment le rapport du rayon extérieur de l'éprou vette sur le rayon de la cavité (r0/ri), l'étude expéri mentale de ROBERTSON (1955) indique qu'il existe un seuil dont la valeur est 3 environ.…”

Section: Les Tubes éPais (Ou « Cylindres Creux »)unclassified

Quelques réflexions sur les biais d’observation lors des essais sur les modèles réduits de forage

Santarelli¹

1992

Rev. Fr. Geotech.

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Quelques réflexions sur les biais d'observation lors des essais sur les modèles réduits de forageSome thoughts about biassed observations during the testing of small scale models of wellbores AbstractThis paper presents some thoughts about the bias and the reality of the obser vations which can be made during the testing of small scale wellbores. After an introduction which explains the importance of such tests in an industrial envi ronment, it lists the different geometries used. A systemetic study of the tes ting machines and of the testing conditions highlights the potential areas where bias may occur during the observations. A series of illustrative examples are given in the fields of scale effects and failure modes.* 64018 Pau Cedex. N° 59 REVUE FRANÇAISE DE GÉOTECHNIQUE

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The failure of thick-walled hollow cylinders of isotropic rock

Cited by 67 publications

References 15 publications

Hollow Cylinder Simulation Experiments of Galleries in Boom Clay Formation

Hollow Cylinder Simulation Experiments of Galleries in Boom Clay Formation

Two problems in rock mechanics arising out of the working of deep ore or coal deposits

Quelques réflexions sur les biais d’observation lors des essais sur les modèles réduits de forage

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