Artykuły w czasopismach: „Hollow Cylinder Trosional Shear Tests”

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Silvestri, V. "On the determination of the stress-strain curve of clay from the undrained plane-strain expansion of hollow cylinders: a long-forgotten method". Canadian Geotechnical Journal 35, nr 2 (1.04.1998): 360–63. http://dx.doi.org/10.1139/t97-084.

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This paper presents the method to obtain the shear stress curve of clay from the undrained plane-strain expansion of hollow cylinder triaxial tests. No prior knowledge of the constitutive properties of the material is required. The theory also indicates that when the outer radius of the cylinder is very large compared with the inner radius, the equation used to interpret pressuremeter tests in clay is recovered.Key words: hollow cylinder, expansion tests, clays, plane strain, undrained condition, shear stress curve.

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Wrzesiński, Grzegorz, i Zbigniew Lechowicz. "Testing of Undrained Shear Strength in a Hollow Cylinder Apparatus". Studia Geotechnica et Mechanica 37, nr 2 (1.06.2015): 69–73. http://dx.doi.org/10.1515/sgem-2015-0023.

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Abstract The paper presents the results of tests performed in a Torsional Shear Hollow Cylinder Apparatus on undisturbed cohesive soils. The tests were performed on lightly overconsolidated clay (Cl) and sandy silty clay (sasiCl). The main objective of the tests was to determine the undrained shear strength at different angles of rotation of the principal stress directions. The results of laboratory tests allow assessing the influence of rotation of the principal stress directions on the value of undrained shear strength that should be used during designing structure foundations

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Lade, Poul V., Jungman Nam i Won Pyo Hong. "Shear banding and cross-anisotropic behavior observed in laboratory sand tests with stress rotation". Canadian Geotechnical Journal 45, nr 1 (styczeń 2008): 74–84. http://dx.doi.org/10.1139/t07-078.

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Shear banding in Santa Monica beach sand deposited by dry pluviation in hollow cylinder specimens is studied in 34 drained torsion shear tests with rotation of principal stress directions. The effect of the specimen height on the soil behavior was investigated by testing specimens with heights of 40 and 25 cm. Each test was conducted with the same, constant inside and outside confining pressure, σr, thus tying the value of b = (σ2– σ3)/(σ1 – σ3) to the inclination, β, of the major principal stress. Shear bands can develop freely without significant restraint from the soft rubber membranes. Strain localization and shear banding were observed in the hollow cylinder specimens, and this created failure conditions in plane strain and in tests with higher b-values. The results clearly indicate the influence of the cross-anisotropic fabric on the stress–strain behavior, on the shear band inclination, and on the shape of the failure surface.

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Sãyao, A., i Y. P. Vaid. "Effect of intermediate principal stress on the deformation response of sand". Canadian Geotechnical Journal 33, nr 5 (6.11.1996): 822–28. http://dx.doi.org/10.1139/t96-108-328.

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An experimental investigation of the relevance of the intermediate principal stress (σ2) on the deformation response of a sand is presented. The effects of σ2 are conveniently studied through the nondimensional stress parameter b = (σ2 σ3)/(σ1 σ3). A series of stress path tests was performed on Ottawa sand specimens in a hollow cylinder torsional shear device. The experimental program includes shear loading at different values of b, and special b tests, in which b was continuously varied at different stress directions. It is shown that the b value may have a significant influence on the stressstrain response of sand, depending on the loading conditions. Key words: hollow cylinder tests, generalized stress paths, sand, stressstrain behaviour, intermediate principal stress.

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Yoshimine, Mitsutoshi, Recep Özay, Atila Sezen i Atilla Ansal. "Undrained Plane Strain Shear Tests on Saturated Sand Using a Hollow Cylinder Torsional Shear Apparatus". Soils and Foundations 39, nr 2 (kwiecień 1999): 131–36. http://dx.doi.org/10.3208/sandf.39.2_131.

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Richardson, Ian Reginald, David Neil Chapman i Stephen Brown. "Relating Failure Tests Performed in Hollow Cylinder Apparatus to Inherent Anisotropy". Transportation Research Record: Journal of the Transportation Research Board 1526, nr 1 (styczeń 1996): 149–56. http://dx.doi.org/10.1177/0361198196152600119.

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Described are failure tests performed on a fine-grained Leighton Buzzard sand in the Nottingham hollow cylinder apparatus. These tests were conducted to characterize the inherent anisotropy of the material formed during the sample preparation procedure. An image analysis procedure for determining preferred particle orientation is introduced and its derivation discussed. An attempt is subsequently made to relate the statistically significant preferred orientation to the anisotropic shear strength properties of the Leighton Buzzard sand.

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Vaid, Y. P., A. Sayao, Enhuang Hou i D. Negussey. "Generalized stress-path-dependent soil behaviour with a new hollow cylinder torsional apparatus". Canadian Geotechnical Journal 27, nr 5 (1.10.1990): 601–16. http://dx.doi.org/10.1139/t90-075.

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A new hollow cylinder torsional shear apparatus is described. The apparatus is suitable for investigating soil behaviour under generalized stress paths, including principal stress rotations, characteristic of earthquake and offshore-wave loadings. A new, more rational assessment of stress nonuniformity across the wall of the hollow cylinder specimen is made, and the "no go" regions of the stress space are delineated that limit stress nonuniformity to acceptable levels. Operation of the apparatus and experimental procedures for tests on reconstituted specimens of sand are described. Typical results of drained tests on loose and dense sand are presented to illustrate the capabilities of the apparatus as a general stress-path loading device and to highlight the stress-path dependence of soil behaviour, in particular, the deformation response to principal stress rotations. Key words: hollow cylinder apparatus, generalized stress paths, principal stress rotation, sand, deformations.

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Kumruzzaman, Md, i Jian-Hua Yin. "Influences of principal stress direction and intermediate principal stress on the stress–strain–strength behaviour of completely decomposed granite". Canadian Geotechnical Journal 47, nr 2 (luty 2010): 164–79. http://dx.doi.org/10.1139/t09-079.

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The measurement and study of the stress–strain–strength behaviour of soils in general stress states involving the change of magnitudes and direction of the principal stresses are necessary and important. To investigate the strength behaviour under such conditions, consolidated undrained tests on remoulded hollow cylinder specimens of completely decomposed granite (CDG) were carried out using a hollow cylinder apparatus. Tests were conducted by maintaining a fixed principal stress direction with angle α from the vertical direction together with a fixed value of intermediate principal stress coefficient b. It is observed that the value of the friction angle decreases with an increase in α and the failure surface is anisotropic. There is an increase in friction angle with an increase in b value up to b = 0.25, and the friction angles are almost the same for b > 0.25. In addition, the behaviour of the soil in an undrained simple shear condition was examined. The simple shear condition is very near to the condition of α = 45° and b = 0.25. After having analyzed the test results of all hollow cylinder specimens, it was found that the strength anisotropy is very strong and is dependent on the principal stress direction and intermediate principal stress coefficient.

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Zdravkovic, Lidija, i Richard J. Jardine. "Undrained anisotropy of K0-consolidated silt". Canadian Geotechnical Journal 37, nr 1 (1.02.2000): 178–200. http://dx.doi.org/10.1139/t99-094.

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Direct measurements of the initial shear strength and yielding anisotropy of a dense, K0-consolidated silt are described and interpreted within a bounding-surface framework. The experiments were performed using the Imperial College large hollow cylinder apparatus, in which samples were sheared undrained with a range of orientations, α, of the major principal stress, σ1, following initial K0 consolidation. The interpretation is aided by data from oedometer and triaxial stress path tests. Strongly anisotropic stiffness, yielding, undrained strength, and mobilized angle of shearing resistance, ϕ', characteristics are revealed. The effects of drained and undrained stress changes applied to the samples after K0 consolidation are also described.Key words: anisotropy, hollow cylinder, K0 consolidation, silt, bounding surface.

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Georgiannou, V. N., i A. Tsomokos. "Comparison of two fine sands under torsional loading". Canadian Geotechnical Journal 45, nr 12 (grudzień 2008): 1659–72. http://dx.doi.org/10.1139/t08-083.

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In this paper the behaviour of two “standard research sands”, widely used for experimental purposes, is compared in a torsional hollow cylinder apparatus under monotonic and cyclic loading conditions. Both sands are fine and uniform with D50 = 0.22 and 0.29 mm, respectively. However, their response to undrained monotonic loading at similar void ratios is dramatically different, with the finer sand showing strength reduction after peak and the coarser sand showing continuous increase in strength with torsional shear. The difference in response is mainly attributed to grain angularity and to a lesser degree to their grading. The results of drained torsional hollow cylinder tests show initial contraction followed by dilation. The stress ratio at phase transformation is uniquely defined by both drained and undrained tests for each sand. Cyclic loading instability is manifested by a sudden increase in shear strain and excess pore-water pressure leading to initial liquefaction. The instability initiates across the instability line for the sand showing strength reduction and across the phase transformation line for the sand showing continuous increase in strength with shearing. Both lines are defined under monotonic loading conditions. The liquefaction, stiffness, and damping characteristics of the sands are given in this paper.

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Shahnazari, Habib, Yaser Jafarian, Mohammad A. Tutunchian i Reza Rezvani. "Undrained Cyclic and Monotonic Behavior of Hormuz Calcareous Sand Using Hollow Cylinder Simple Shear Tests". International Journal of Civil Engineering 14, nr 4 (czerwiec 2016): 209–19. http://dx.doi.org/10.1007/s40999-016-0021-6.

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Sivathayalan, S., i Y. P. Vaid. "Influence of generalized initial state and principal stress rotation on the undrained response of sands". Canadian Geotechnical Journal 39, nr 1 (1.02.2002): 63–76. http://dx.doi.org/10.1139/t01-078.

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The dependence of the undrained behaviour of sand on the initial stress state and the orientation of principal stresses with respect to the bedding planes is assessed under generalized loading paths using hollow cylinder torsional shear tests. The undrained tests were carried out using displacement-controlled loading to confidently capture the post-peak strain-softening response. Undrained behaviour of sands under identical initial states is shown to be dependent on the direction of principal stresses, during and prior to undrained shear, in relation to the direction of bedding planes. The minimum undrained strength of the strain-softening sand is found to be highly influenced by the initial stress state (confining stress, direction of principal stresses, and static shear), even though the friction angle mobilized at the instant of minimum strength is unique. A mere rotation of principal stresses at constant deviator stress alone can lead to a strain-softening response that may culminate in limited or unlimited flow deformation. The susceptibility of sand to liquefaction due to stress rotation increases as the direction of the major principal stress approaches the orientation of the bedding plane. The potential for flow deformation is strongly dependent on the direction of the major principal stress in relation to the bedding planes, and the steady state strength is not uniquely related to the void ratio alone.Key words: liquefaction, hollow cylinder torsion test, principal stress direction, static shear, steady state strength, minimum undrained strength.

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Pan, Hua, Guo Xing Chen i Tian Sun. "Experimental Research on Dynamic Poisson’s Ratio of Silty Clay". Advanced Materials Research 168-170 (grudzień 2010): 286–92. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.286.

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Cyclic triaxial and cyclic torsional shear tests were performed on undisturbed marine silty clay by the hollow cylinder apparatus, and the Young’s modulus and shear modulus were obtained respectively. Furthermore, the influence of effective confining pressure and stress ratio on dynamic Poisson’s ratio was investigated on this basis. It was found that the dynamic Poisson’s ratio increases with generalized shear strain, but decreases with increasing effective confining pressure and stress ratio. The effect of effective confining pressure and stress ratio on dynamic Poisson’s ratio was weakened as the generalized shear strain was increasing. The dynamic Poisson’s ratio was about 0.48 when the Poisson’s ratio was increased to 1.8E-2 or so, and the test was terminated. There was no shear dilatation during all tests because the Poisson’s ratios were smaller than 0.5. It indicates that the marine silty clay tested in this paper has a good stability under cyclic loads.

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Wrzesiński, Grzegorz, i Zbigniew Lechowicz. "Influence of the rotation of principal stress directions on undrained shear strength". Annals of Warsaw University of Life Sciences - SGGW. Land Reclamation 45, nr 2 (1.12.2013): 183–92. http://dx.doi.org/10.2478/sggw-2013-0015.

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Abstract Influence of the rotation of principal stress directions on undrained shear strength. The paper presents the results of research on natural cohesive soil carried out in the Hollow Cylinder Apparatus (HCA). The main goal of this study was to determine the values of undrained shear strength at different angle of the rotation of principal stress directions. The research were carried out with anisotropic consolidation and shearing in undrained conditions (CAU) on cohesive soil with overconsolidation ratio (OCR) equals 4 and plasticity index (Ip) about 77%. The results of laboratory tests allow to assess the influence of the rotation of principal stress directions on undrained shear strength

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Mamou, Anna, William Powrie, Jeffrey Priest i Chris Clayton. "The use of the hollow cylinder apparatus to study stress paths relevant to railway track foundations". E3S Web of Conferences 92 (2019): 02013. http://dx.doi.org/10.1051/e3sconf/20199202013.

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This paper presents and discusses results from a series of hollow cylinder tests, carried out to investigate the effects of principal stress rotation on the resilient response of soils in stress paths relevant to railway track foundations. Four sand-clay mixes, typical of the gradation of an in situ railway track foundation, were investigated. The aim of the research was to investigate the magnitudes of shear stress cycles for which the associated cyclic rotations of the principal stress direction may have a significant effect on the long-term stability of a railway track foundations.

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Huang, Bo, Xing Yao Chen, Qing Jing Wang i Dao Sheng Ling. "A New Parameter to Evaluate Liquefaction Resistance of Saturated Sand under Complex Dynamic Stress Paths". Applied Mechanics and Materials 405-408 (wrzesień 2013): 378–85. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.378.

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Foundations are often subjected to complex dynamic stresses which result from ocean wave, vehicle or seismic loads. In this paper, four series of tests under different dynamic stress paths were carried out on Fujian standard sand with hollow cylinder apparatus, to investigate its liquefaction resistance. Test results showed different strength of specimens under different dynamic stress paths, when using the traditional evaluation index: maximum cyclic shear stress. A concept named as load efficiency (E) was proposed in this paper, which is defined as definite integral of dynamic shear stress on time in a single cycle. E is a new parameter to characterize liquefaction resistance of non-cohesive soil, attempting to normalize the effect of different shear modes, in which the shear stresses are constant or change periodically under different dynamic stress paths. Test results showed that in the isotropic consolidation condition, the relationship between E and failure cycle Nf is nearly linear in the dual-log coordinate.

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Suits, L. D., T. C. Sheahan, Nguyen HongNam, Junichi Koseki i Takeshi Sato. "Effect of Specimen Size on Quasi-Elastic Properties of Toyoura Sand in Hollow Cylinder Triaxial and Torsional Shear Tests". Geotechnical Testing Journal 31, nr 2 (2008): 100022. http://dx.doi.org/10.1520/gtj100022.

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Cui, Lan, Qian Sheng, Zhenzhen Niu i Liuming Chang. "Deformation Behavior of Saturated Marine Silt under Principal Stress Rotation as Induced by Wave Loading". Applied Sciences 11, nr 20 (12.10.2021): 9458. http://dx.doi.org/10.3390/app11209458.

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An experimental study aimed at providing insights into the cyclic deformation behavior of saturated marine silt under principal rotation, as induced by wave loading, is presented. Using the GDS hollow cylinder apparatus, a series of undrained tests are performed and the specimens at identical initial states are subjected to combined axial–torsional cyclic loading that imposes different levels of stress rotation. The cumulative generalized shear strain γg is used to describe the deformation of the silt under complex stress paths. The test results show that the cumulative generalized shear strain is significantly dependent on the cyclic stress ratio (CSR) and cyclic loading amplitude ratio δ. The cumulative generalized shear strain increases with the increase in CSR and decreases with the increase in δ. The development trend of γg can be well predicted through the correct Monismith model in the non-liquefaction silt, with a low error that is generally less than 10%.

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Mamou, Anna, Jeffrey A. Priest, Christopher R. I. Clayton i William Powrie. "Behaviour of saturated railway track foundation materials during undrained cyclic loading". Canadian Geotechnical Journal 55, nr 5 (maj 2018): 689–97. http://dx.doi.org/10.1139/cgj-2017-0196.

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This paper presents results of a series of hollow cylinder tests carried out to investigate the undrained behaviour of saturated railway track foundation materials during cyclic loading involving principal stress rotation. Four sand–clay mixes representative of real railway track foundation materials were investigated. It was found that moderate additions of clay (up to ∼14% by weight) increased the cyclic shear stress threshold at which significant excess pore pressures started to accumulate. After the cyclic shear stress threshold had been exceeded, the rate of pore pressure increase with the logarithm of axial strain was greatest for the material having a clay content of 11%. Excess pore pressure generation reduced with increasing intergranular and global void ratio, with the global void ratio being perhaps the more useful indicator because of the reduced amount of scatter and higher correlation of the idealized relationship.

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Tsomokos, A., i V. N. Georgiannou. "Effect of grain shape and angularity on the undrained response of fine sands". Canadian Geotechnical Journal 47, nr 5 (maj 2010): 539–51. http://dx.doi.org/10.1139/t09-121.

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The objective of this paper is to discuss the effect of grain shape and angularity on the undrained behaviour of sands. Four fine to medium (D50 = 0.15–0.29 mm) and uniform sands were examined. These sands have similar and (or) identical grading curves, but differ with respect to the angularity of their grains. Under the electron scanning microscope two sands have rounded grains and the other two have subangular to angular grains. For sands with rounded grains, evidence of undrained behaviour undergoing systematic weakening (shear stress reduction after a transient peak deviator stress) is provided by torsional hollow cylinder tests. However, sands with the same grading curve and void ratio, but angular grains, show stable response with a continuous increase in strength after a transient peak. A small variation in the sand gradation, i.e., D50 = 0.22 ± 0.07 mm, does not appear to alter the pattern of undrained response described earlier, with the angular sand (D50 = 0.15) exhibiting stable response to shear and the rounded sands (D50 = 0.22 and 0.29) having unstable response to shear. The stiffness characteristics of the sands are also presented. Triaxial compression tests were performed to confirm the pattern of response observed under torsional testing.

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Saito, Shunsuke, Fumio Ogawa i Takamoto Itoh. "Fatigue Life Properties of Stainless Steels in Wide Ranged Biaxial Stress States using a Hollow Cylinder Specimen". MATEC Web of Conferences 300 (2019): 09004. http://dx.doi.org/10.1051/matecconf/201930009004.

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Stress controlled multiaxial fatigue tests were carried out using hollow cylinder specimens of type 430 and 316 stainless steels at room temperature. A newly developed fatigue testing machine which can apply push-pull loading and inner pressure to the specimen was used. For inner pressure, oil was put inside of the specimen. 7 types of cyclic loading paths were employed by combining axial and hoop stresses; a Pull, an Inner-pressure, a Push-pull, an Equi-biaxial, a Square-shape, a LT-shape and a LC-shape. Fatigue lives vary depending on the loading path when those were evaluated by the maximum Mises’ equivalent stress range on inner surface of the specimen. The fatigue lives of both the steels showed a similar tendency. However, the following difference was identified. Specifically, differences in fatigue lives of type 430 stainless steel between the uniaxial loading and the multiaxial tests were large, while those of type 316 stainless steel were small. To discuss difference in fatigue life properties between both steels, this study investigates the effect of the shear stress range, mean stress and additional hardening and which leads to evaluate the lives suitably.

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Brosse, A., R. J. Jardine i S. Nishimura. "Undrained stiffness anisotropy from hollow cylinder experiments on four Eocene-to-Jurassic UK stiff clays". Canadian Geotechnical Journal 54, nr 3 (marzec 2017): 313–32. http://dx.doi.org/10.1139/cgj-2015-0320.

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The paper describes the anisotropic undrained stiffness behaviour of four medium-plasticity heavily overconsolidated UK stiff marine clays as revealed through hollow cylinder testing. The experiments contributed to two broader studies on stiff-to-hard London, Gault, Kimmeridge, and Oxford clay strata. They involved static and dynamic testing of multiple high-quality natural specimens sampled at similar depths from inland sites. This paper explores the directional dependency of the clays’ highly nonlinear undrained stiffness characteristics. New data-analysis approaches are outlined that allow the stiffnesses associated with one-dimensional vertical, horizontal, or pure horizontal shear modes to be isolated in complex undrained stress paths. In the presented experiments, loading progressed from in situ stresses to reach ultimate failure at a range of final major principal stress orientation angles α (defined in the vertical plane) while keeping fixed values of the intermediate principal stress ratio, b. The tests reveal strong undrained stiffness anisotropy that can impact significantly on the prediction and understanding of ground deformation patterns in numerous geotechnical engineering applications.

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Ratananikom, Wanwarang, Siam Yimsiri, Fumihiko Fukuda i Suched Likitlersuang. "Failure Surface and Plastic Potential in Deviatoric Plane of Bangkok Clay". Applied Mechanics and Materials 256-259 (grudzień 2012): 256–60. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.256.

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This paper presents an experimental investigation on the failure surface and plastic potential in deviatoric plane of Bangkok Clay. The results of torsional shear hollow cylinder and triaxial tests with various principal stress directions and magnitudes of intermediate principal stress on undisturbed Bangkok Clay specimens are presented. The obtained stress-strain behaviors assert clear evidences of anisotropic characteristics of Bangkok Clay. Both failure surface and plastic potential in deviatoric plane of Bangkok Clay are demonstrated as isotropic and of circular shape (Drucker-Prager type) which implies an associated flow rule. Concerning the behavior of Bangkok Clay found from this study, the discussions on the effects of employed constitutive modeling approach on the resulting numerical analysis are made.

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Reid, D., R. Fanni i A. Fourie. "Assessing the undrained strength cross-anisotropy of three tailings types". Géotechnique Letters 12, nr 1 (marzec 2022): 1–7. http://dx.doi.org/10.1680/jgele.21.00094.

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The cross-anisotropic nature of soil strength has been studied and documented for decades, including the increased propensity for cross-anisotropy in layered materials. However, current engineering practice for tailings storage facilities (TSFs) does not appear to generally include cross-anisotropy considerations in the development of shear strengths. This is despite the very commonly seen layering profile in subaerially deposited tailings. To provide additional data to highlight the strength cross-anisotropy of tailings, high-quality block samples from three TSFs were obtained and trimmed to enable hollow cylinder torsional shear tests to be sheared at principal stress angles of 0 and 45° during undrained shearing. The consolidation procedures were carried out such that the drained rotation of principal stress angle that would precede potential undrained shear events for below-slope tailings was reasonably simulated. The results indicated the significant effects of cross-anisotropy on the undrained strength, instability stress ratio, contractive tendency and brittleness of each of the three tailings types. The magnitude of cross-anisotropy effects seen was generally consistent with previous published data on sands.

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Corte, Marina Bellaver, Erdin Ibraim, Lucas Festugato, Andrea Diambra i Nilo Cesar Consoli. "Stiffness of lightly cemented sand under multiaxial loading". E3S Web of Conferences 92 (2019): 11008. http://dx.doi.org/10.1051/e3sconf/20199211008.

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This paper presents experimental triaxial tests conducted on two lightly cemented sand samples on the set-up conditions of a Hollow Cylinder Torsional Apparatus (HCTA). The laboratory study has been carried out on an angular to sub-angular silica sand reinforced with Portland cement of high early strength. The samples have identical porosity/volumetric cement content ratio, η/Civ, values. The Young's modulus and shear modulus were measured by the application of a series of small unload-reload cycles at different investigation points along the triaxial stress path up to about 50% of the maximum deviatoric stress. At these investigation points, additional series of unload-reload cycles of higher amplitudes were also applied and the stiffness moduli assessed using local instrumentation. While the peak strength seems to be controlled by the density of the sand matrix, as extensive bond cementation damages occur at peak and pre-peak stages, the Young's modulus and shear modulus normalised by the void ratio function show the effect of the cementation ratio with higher values for the sample with higher cementation ratio.

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Cai, Yuanqiang, Qi Sun, Lin Guo, C. Hsein Juang i Jun Wang. "Permanent deformation characteristics of saturated sand under cyclic loading". Canadian Geotechnical Journal 52, nr 6 (czerwiec 2015): 795–807. http://dx.doi.org/10.1139/cgj-2014-0341.

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The loading path involving principal stress rotation (PSR) during shear is an important phenomenon encountered in many field conditions. Typically for traffic loading, both the magnitude and direction of principal stresses may vary with time due to the motion of vehicles, and the stress path can be mimicked by a heart shape in the deviatoric stress space. Conventional triaxial tests are not suitable to recreate this type of stress path in that no torsional shear stress can be applied on the test samples. To overcome this limitation, a series of tests using a hollow cylinder apparatus were conducted on sand to investigate the permanent deformation characteristics under drained conditions with different levels of confining pressure (σc), cyclic vertical stress ratio (CVSR), and cyclic torsional stress ratio (η). The results clearly show an increase in the permanent deformation with η, indicating that the PSR effect on permanent deformation cannot be ignored. Both σc and CVSR were found to also affect permanent deformation, which was more pronounced when PSR was coupled into the test. A five-parameter formulation that accounted for the effect of confining pressure, deviatoric stress, torsional shear stress, and number of loading cycles was subsequently established to analyze the permanent strain. The formulation coefficients were first determined and then used to explain the effects of stress variables on the permanent deformation. Validation studies were performed to address the adequacy of the formulation to predict permanent deformation.

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Yu, H. S., i X. Yuan. "On a class of non-coaxial plasticity models for granular soils". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 462, nr 2067 (14.12.2005): 725–48. http://dx.doi.org/10.1098/rspa.2005.1590.

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The non-coaxiality of the directions of principal stresses and principal plastic strain rates in granular soils under stress rotations has long been observed and recognized in soil tests using both simple shear and hollow cylinder apparatuses. A few constitutive theories have also been proposed in the literature to account for the effect of stress rotations and the subsequent non-coaxial soil behaviour, particularly in the context of shear band analysis. However, the lack of corresponding general numerical methods makes it difficult to investigate the influence of non-coaxial stress–strain behaviour on the results of geotechnical boundary value problems. This paper presents a numerical evaluation of a class of non-coaxial, elastic–plastic models that are developed by combining the conventional plastic potential theory and the double shearing theory. The general non-coaxial constitutive theories are first formulated and then a finite element implementation of the theories is carried out. To evaluate the non-coaxial theories, the problem of simple shear of soils is chosen to investigate the predicted behaviour of soils under simple shear loading conditions where the axes of principal stresses rotate. In particular, the influence of initial stress states and the degree of non-coaxiality are examined. It is found that the numerical results predicted using the non-coaxial model are in general agreement with the experimental observations reported in the literature.

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Guo, Lin, Yuanqiang Cai, Richard J. Jardine, Zhongxuan Yang i Jun Wang. "Undrained behaviour of intact soft clay under cyclic paths that match vehicle loading conditions". Canadian Geotechnical Journal 55, nr 1 (styczeń 2018): 90–106. http://dx.doi.org/10.1139/cgj-2016-0636.

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Vehicle traffic loading appears to contribute significantly to long-term settlement beneath highways, airport runways, and metro lines in China. Wheel loading imposes cycles in both the magnitude and direction of the principal stresses acting on the soils beneath pavement or rail-track structures. Conventional cyclic triaxial (CT) testing, which is not capable of imposing such stress paths, may underestimate how heavy traffic loading affects any underlying soft clay layers. A hollow cylinder apparatus (HCA) can simulate such traffic loading stress paths more accurately, including rotation of the principal stress directions. This paper presents a systematic experimental study of cyclic HCA (CHCA) tests on K0-consolidated saturated soft clay involving cyclic variations in both vertical and torsional shear stresses, along with a parallel programme of CT tests, considering the undrained response of saturated samples of intact soft clay. It is shown that when applied above certain critical cyclic stress ratios, principal stress rotation accelerates excess pore-water pressure and permanent strain development. Corresponding changes are also seen in the resilient modulus and damping ratio trends. The discrepancies between the behaviour of CHCA and equivalent CT tests grow as the cyclic stress ratios increase.

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Zhou, Jian, Jiajia Yan, Changjie Xu i Xiaonan Gong. "Influence of Intermediate Principal Stress on Undrained Behavior of Intact Clay under Pure Principal Stress Rotation". Mathematical Problems in Engineering 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/950143.

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This study presents the accumulations of the excess pore water pressure and the deformation as well as the noncoaxial behavior of intact soft clay subjected to pure principal stress rotation. Series of tests were carried out by using a dynamic hollow cylinder apparatus to highlight the influence of intermediate principal stress parameterb. It was found that the rate of PWP evolution was greatly influenced byb, but the influence was not monotonous. Specimens under the conditionb= 0.75 had the highest accumulation of pore water pressure while under the conditionb= 0 had the strongest resistance to the pore pressure generation. PWP accumulated mainly in the first cycle. The failure of specimens under principal stress rotation was controlled by the strain other than the pore pressure. The shear stiffness decreased more quickly with higherbvalue. The direction of the principal strain increment was strongly dependent on the principal stress increment orientation and less influenced by thebvalue and the number of cycles.

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Chen, Dun, Guoyu Li, Xiaodong Zhao, Wei Ma, Zhiwei Zhou, Yanhu Mu, Zejin Lai i Tuo Chen. "Experimental Study on the Anisotropy and Non-coaxiality of Frozen Standard Sand under Different Principal Stress Directions". Geofluids 2022 (14.05.2022): 1–15. http://dx.doi.org/10.1155/2022/1585324.

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Owing to the limitations of the apparatus, the influence of its principal stress direction on the anisotropic behavior and non-coaxiality of frozen soil has not been fully considered in previous studies. At a temperature of -10°C, a series of hollow cylinder tests for frozen standard sand (FSS) was conducted under different directional angles of major principal stress and mean principal stresses in this study. The experimental results indicate that the stress-strain-strength anisotropy and non-coaxiality of the FSS are highly dependent on the principal stress direction. The stress components of the FSS vary linearly with increasing shear stress at different directional angles of the major principal stress and mean principal stresses. With a linear increase in shear stress, the strain components of the FSS exhibited a nonlinear increasing trend. The FSS strength gradually decreased as the directional angle of the major principal stress and the mean principal stresses in the test range increased. Under the different principal stress directions, the non-coaxiality of the FSS, non-coincidence of the direction of the principal strain increment and the principal stress direction, were observed. The directions of the principal strain increment and principal stress gradually tended to be coaxial as shear stress increased. Although the non-coaxial angle of the FSS increased gradually with an increase in the directional angles of the major principal stress, it did not change with the change in the mean principal stress. The non-coaxial angle of the FSS was observed to be as large as 35° in the early stage of shearing under different mean principal stresses.

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Vargas, Ruben R., Kyohei Ueda i Kazuaki Uemura. "Influence of the relative density and K0 effects in the cyclic response of Ottawa F-65 sand - cyclic Torsional Hollow-Cylinder shear tests for LEAP-ASIA-2019". Soil Dynamics and Earthquake Engineering 133 (czerwiec 2020): 106111. http://dx.doi.org/10.1016/j.soildyn.2020.106111.

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Lekarp, Fredrick, Ian Reginald Richardson i Andrew Dawson. "Influences on Permanent Deformation Behavior of Unbound Granular Materials". Transportation Research Record: Journal of the Transportation Research Board 1547, nr 1 (styczeń 1996): 68–75. http://dx.doi.org/10.1177/0361198196154700110.

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The results of a research program aimed at characterizing the permanent deformation behaviors of different types of unbound aggregates under repeated loading are summarized. Tests were performed in a triaxial or hollow-cylinder apparatus, depending on the grading of the materials. The scope of the research was to assess the relationship between total permanent axial strain and both the number of load applications and the stress level. The test results were used to verify a model recently developed in France in which attempts are made to predict the long-term behaviors of granular materials. The French model is examined with particular reference to its validity on the effect of stress level on permanent deformation of unbound granular materials. The results of the study indicate that the French model is generally successful in predicting the permanent strain for a given number of load applications. For one of the materials, however, the model did not seem to fit the data well. The French model also suggests that the variation in total permanent strain with stress level is related to the static failure line and could be determined by comparing the maximum shear stress ratio with the slope of the estimated failure line. This is discussed and shown to be questionable because it results in either unreasonable failure parameters or a very low level of correlation with the observations. An attempt was made to modify the French model, but that also proved to be unsuccessful. The concept of relating the permanent deformation behavior to the static failure condition of the material is therefore questioned.

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"Comparison of direct shear and hollow cylinder tests on rock joints". International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 29, nr 6 (listopad 1992): 349. http://dx.doi.org/10.1016/0148-9062(92)91699-6.

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Su, Donghua, Jin Li, Sheng Huang, Zaoyuan Li i Xuning Wu. "Novel Method for Characterizing the Mechanical Properties of the Cement Sheath Based on Hollow-Cylinder Specimen and Multiaxial Load Tests". SPE Journal, 1.12.2022, 1–15. http://dx.doi.org/10.2118/214293-pa.

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Summary Mechanical properties such as Young's modulus, Poisson's ratio, and strength are important parameters for evaluating the cement sheath integrity. However, the current triaxial testing methods for the mechanical properties of intact-cylinder cement specimens ignore the “ring” shape of the wellbore cement sheath and its nonuniform 3D stress distribution, which may lead to deviations from the actual mechanical properties of the wellbore cement sheath that can affect the theoretical analysis results. In this study, we designed a hollow-cylinder cement specimen to address the aforementioned conditions and conducted uni, tri, and multiaxial compression tests to analyze the differences in the deformation, damage, and mechanical failure of the hollow- and intact-cylinder cement specimens. It was found that under the same confining pressure, the Young’s modulus of the hollow-cylinder cement specimen with hole pressure was approximately 1.2 times that of the intact-cylinder cement specimen; however, the difference in Poisson’s ratio was not significant. The uniformity of the radial and circumferential stress distributions in the hollow-cylinder cement specimens was the main factor affecting the volumetric strain curves and the damage threshold. Under tri and multiaxial compression conditions, the deviatoric stress of the hollow-cylinder cement specimens was higher than that of the intact-cylinder cement specimens. Compared with the Mohr-Coulomb criterion, the twin-shear unified strength theory can more accurately reflect the relationships between the radial, circumferential, and axial stresses and the strength of the hollow-cylinder cement specimens. Through a failure test of the cement sheath based on a self-developed wellbore simulation device, it was verified that the mechanical properties of the hollow-cylinder cement specimens can better reflect the failure law of the wellbore cement sheath compared with intact-cylinder cement specimens. The findings of this study can contribute to the understanding of the mechanical behavior of wellbore cement sheaths.

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Liu, Xinyu, Xianwei Zhang, Lingwei Kong, Gang Wang i Chengsheng Li. "Multiscale structural characterizations of anisotropic natural granite residual soil". Canadian Geotechnical Journal, 28.02.2023. http://dx.doi.org/10.1139/cgj-2022-0188.

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While the anisotropy of sedimentary soil—particularly the underlying role of soil structure—is well understood, similar knowledge about granite residual soil formed by weathering is scarce. In particular, the evolution of soil structure during the hollow cylinder torsional shear tests (among the most appropriate for studying soil strength anisotropy) remains largely unknown. This study systematically investigates the multiscale structural properties of granite residual soil using stereo microscopy, scanning electron microscopy, energy-dispersive spectrometry, and computed tomography. Furthermore, the structural evolution during hollow cylinder torsional shear tests is traced. Results indicate the strength anisotropy of residual soil is associated with horizontal fissures which cause low shear strength when the soil is sheared with a principal stress direction of 45°. The cementation via Fe is characterized by a uniform distribution. Different evolutionary patterns are observed for soils within the shear band, inside the necking area, and in other regions. It is not always the case that particles are rearranged with their long axis perpendicular to the major principal stress. This study improves the understanding of natural residual soil structure and provides some insights into its anisotropic behavior.

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Fardad Amini, Pedram, i Gang Wang. "Integrated effects of inherent and induced anisotropy on reliquefaction resistance of Toyoura sand with different strain histories". Géotechnique, 6.04.2023, 1–45. http://dx.doi.org/10.1680/jgeot.22.00075.

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Recent earthquakes in New Zealand and Japan showed that preshaking histories significantly affected the reliquefaction resistance of soils. In this study, a series of experimental tests were conducted to elucidate the coupled effects of inherent and induced anisotropy on reliquefaction resistance of Toyoura sand, which have not been studied before. Accordingly, loose and dense Toyoura sands were prepared with two different methods: dry deposition (DD) and moist tamping (MT). The specimens were sheared cyclically using a hollow cylinder torsional shear apparatus (HCTSA) under various cyclic stress ratios (CSR) up to different residual shear strains (γres) and reconsolidated at different states. The experimental results were assessed from various perspectives, including stress-strain relationships, failure mechanisms, liquefaction/reliquefaction resistance, excess pore water pressure (EPWP) generation, and compressibility in conjunction with micromechanical interpretations. It was shown that fabric evolution affects the reliquefaction characteristics of Toyoura sand substantially. Interestingly, a unique correlation exists between EPWP and shear strain accumulation for all tests. An energy-based model was developed to uniquely correlate the dissipated energy with the cyclic resistance based only on residual shear strains, showing a great promise to develop a unified, energy-based criterion for quantifying liquefaction/reliquefaction resistance of soils with different fabrics.

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Fanni, Riccardo, David Reid i Andy Fourie. "Effect of principal stress direction on the instability of sand under the constant shear drained stress path". Géotechnique, 31.08.2022, 1–54. http://dx.doi.org/10.1680/jgeot.22.00062.

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Results of torsional shear hollow cylinder (TSHC) tests carried out on a reconstituted sand maintaining a constant direction of major principal stress relative to the vertical axis (α) and intermediate principal stress ratio (b) during shearing are presented. Tests were undertaken following the constant shear drained (CSD) stress-path, which simulates stress conditions under a rising phreatic surface. The test programme was complemented by undrained TSHC tests to provide further insight on the behaviour of the sand when sheared under a range of α values. Various reconstitution methods (i.e., moist tamped (MT), dry pluviated (DP) and wet pluviated (WP)) were included to examine the effects of fabric on CSD triggering. Only MT and DP specimens could be prepared loose enough to exhibit liquefaction behaviour, hence the focus of this study was on these preparation methods. The programme indicated that the instability stress ratio (ηIL) under the CSD stress paths decreases as α increases, suggesting that cross-anisotropy strongly influences the shearing behaviour of sands under this trigger mechanism. Additionally, the DP sand showed a greater decrease of ηIL with increasing α compared to the MT sand, consistent with other studies examining the effect of fabric and preparation methods on inherent anisotropy. The results of this study suggest that ignoring the effect of cross-anisotropy on the CSD trigger mechanism will lead to unconservative slope stability assessments.

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Prasanna, Rousseau, i Siva Sivathayalan. "Liquefaction of sands subjected to principal stress rotation caused by generalized seismic loading ". Canadian Geotechnical Journal, 8.02.2022. http://dx.doi.org/10.1139/cgj-2021-0035.

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A comprehensive experimental study that quantifies the influence of coupled compression and shear wave loading on liquefaction susceptibility of sands is presented. Such loading leads to complex principal stress rotation, which in turn impacts the potential for liquefaction in soils even if the cyclic loading intensity remains constant. The nature and degree of principal stress rotation caused by coupled loading are significantly influenced by the initial consolidation stress state, and the cyclic shear (ΔS), cyclic normal (ΔN) stress increments, the ratio ∆S⁄∆N, and the phase shift (δ) between the waves. Cyclic hollow cylinder torsional shear tests were carried out on Fraser River sand specimens isotropically consolidated to different 〖σ^'〗_mc and subjected to coupled cyclic loading with representative ∆S⁄∆N. For a given CSR and initial 〖σ^'〗_mc, the liquefaction resistance decreases with increasing s- wave intensity relative to p-wave intensity, which are proxies to stress increments ΔS and ΔN respectively. Liquefaction resistance decreases with an increase in ∆S⁄∆N up to a limiting value of about 2 beyond which increasing ∆S⁄∆N does not significantly influence the cyclic resistance. The finding that cyclic resistance ratio CRR decreases with increasing ΔS⁄ΔN is consistent with the understanding that the cyclic resistance is lower under simple shear loading mode compared to triaxial shear. . This indicates that the K_σ factor can be considered even under generalized coupled loading condition

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Berntsen, Andreas Nicolas, Euripides Papamichos, Xiyang Xie, Gang Li i Ziheng Yao. "Productivity Decline Mechanisms in Gravel Packed Perforations". Rock Mechanics and Rock Engineering, 14.08.2023. http://dx.doi.org/10.1007/s00603-023-03456-3.

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AbstractIn a cased hole gravel pack completion, perforations are packed with proppant to both mechanically support the perforation cavity, and to filter any produced sand before it reaches the surface. Poor perforation packing sometimes occurs in which the perforation is partially or completely unsupported, leading to earlier productivity reduction than in cases of good packing. We investigated productivity reduction and the associated mechanisms in a series of hollow cylinder experiments on outcrop and field cores with varying proppant packing. Packed perforations maintained significantly higher productivity than unsupported perforations by preventing macroscopic shear failure around the cavity and erosion due to sand production. Partial packing may in some instances maintain productivity almost as well as complete packing, but this likely depends on perforation orientation. Compaction tests and numerical simulations suggest that compaction failure is unlikely at the cavity wall in the current experiments, and that proppant-formation interface damage or proppant filtering of produced sand are more probable explanations for the productivity reduction seen in packed perforations.

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