In situ geomechanics of crystalline and sedimentary rocks; Part IX, Prediction of fault slip in a brittle crust under multiaxial loading conditions

AbstractSome of the current concrete damage plasticity models in the literature employ a single damage variable for both the tension and compression regimes, while a few more advanced models employ two damage variables. Models with a single variable have an inherent difficulty in accounting for the damage accrued due to tensile and compressive actions in appropriately different manners, and their mutual dependencies. In the current models that adopt two damage variables, the independence of these damage variables during cyclic loading results in the failure to capture the effects of tensile damage on the compressive behavior of concrete and vice-versa. This study presents a cyclic model established by extending an existing monotonic constitutive model. The model describes the cyclic behavior of concrete under multiaxial loading conditions and considers the influence of tensile/compressive damage on the compressive/tensile response. The proposed model, dubbed the enhanced concrete damage plasticity model (ECDPM), is an extension of an existing model that combines the theories of classical plasticity and continuum damage mechanics. Unlike most prior studies on models in the same category, the performance of the proposed ECDPM is evaluated using experimental data on concrete specimens at the material level obtained under cyclic multiaxial loading conditions including uniaxial tension and confined compression. The performance of the model is observed to be satisfactory. Furthermore, the superiority of ECDPM over three previously proposed constitutive models is demonstrated through comparisons with the results of a uniaxial tension-compression test and a virtual test.

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Discrete element analysis of the punching behaviour of a secured drapery system: from laboratory characterization to idealized in situ conditions

Acta Geotechnica ◽

10.1007/s11440-020-01119-z ◽

2021 ◽

Author(s):

Antonio Pol ◽

Fabio Gabrieli ◽

Lorenzo Brezzi

Keyword(s):

Mechanical Response ◽

Steel Wire ◽

Discrete Element ◽

Wire Mesh ◽

Steel Plates ◽

Loading Conditions ◽

Element Analysis ◽

In Situ Conditions ◽

Wire Meshes

AbstractIn this work, the mechanical response of a steel wire mesh panel against a punching load is studied starting from laboratory test conditions and extending the results to field applications. Wire meshes anchored with bolts and steel plates are extensively used in rockfall protection and slope stabilization. Their performances are evaluated through laboratory tests, but the mechanical constraints, the geometry and the loading conditions may strongly differ from the in situ conditions leading to incorrect estimations of the strength of the mesh. In this work, the discrete element method is used to simulate a wire mesh. After validation of the numerical mesh model against experimental data, the punching behaviour of an anchored mesh panel is investigated in order to obtain a more realistic characterization of the mesh mechanical response in field conditions. The dimension of the punching element, its position, the anchor plate size and the anchor spacing are varied, providing analytical relationships able to predict the panel response in different loading conditions. Furthermore, the mesh panel aspect ratio is analysed showing the existence of an optimal value. The results of this study can provide useful information to practitioners for designing secured drapery systems, as well as for the assessment of their safety conditions.

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In situ monitoring of dislocation, twinning, and detwinning modes in an extruded magnesium alloy under cyclic loading conditions

Materials Science and Engineering A ◽

10.1016/j.msea.2021.140860 ◽

2021 ◽

Vol 806 ◽

pp. 140860

Author(s):

Di Xie ◽

Zongyang Lyu ◽

Yuan Li ◽

Peter K. Liaw ◽

Huck Beng Chew ◽

...

Keyword(s):

Magnesium Alloy ◽

Cyclic Loading ◽

In Situ Monitoring ◽

Loading Conditions

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A Road Section near Guy's Hill, Jamaica

Geological Magazine ◽

10.1017/s0016756800073933 ◽

1942 ◽

Vol 79 (4) ◽

pp. 241-252 ◽

Cited By ~ 3

Author(s):

C. A. Matley ◽

Frank Raw

Keyword(s):

Sedimentary Rocks ◽

Plutonic Rock ◽

Igneous Rocks ◽

The Road ◽

Road Section ◽

Igneous Intrusions ◽

Microscope Slides

The rocks exposed along the road between Linstead and Guy's Hill, Jamaica, were described by Dr. C. T. Trechmann in this magazine in 1936 (pp. 259–260). The chief object of his account was to prove that the igneous rocks there were intrusions later than the associated Cretaceous and Tertiary limestones, which, according to him, had been metamorphosed into hornfelses, some of which, he stated later (1937, p. 561), he knew to have an “igneous” appearance under the microscope, “which tends to support my contention that in Jamaica we have sedimentaries altered in situ into rocks that would ordinarily be classified as igneous.” Dissent from his descriptions and interpretations was expressed by C. A. M. (Matley, 1937, pp. 501–3), the criticisms being mainly based on an examination of Trechmann's own microscope slides by F. R. A visit to Jamaica by C. A. M. in 1939 allowed him to study this road and to collect a suite of rocks for petrological examination. The results show that Trechmann's interpretation cannot be sustained. There is no granodiorite or other plutonic rock present, no metamorphism hornfelsing the sedimentary rocks, and no igneous intrusions into the Tertiary limestones.

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In Situ Forces in the Anteromedial and Posterolateral Bundles of the Anterior Cruciate Ligament under Simulated Functional Loading Conditions

The American Journal of Sports Medicine ◽

10.1177/0363546509350110 ◽

2010 ◽

Vol 38 (3) ◽

pp. 558-563 ◽

Cited By ~ 39

Author(s):

Jia-Lin Wu ◽

Jong Keun Seon ◽

Hemanth R. Gadikota ◽

Ali Hosseini ◽

Karen M. Sutton ◽

...

Keyword(s):

Anterior Cruciate Ligament ◽

Cruciate Ligament ◽

Loading Conditions ◽

Anterior Cruciate ◽

Functional Loading

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Late Mesozoic—Cenozoic clay mineral successions of southern Iran and their palaeoclimatic implications

Clay Minerals ◽

10.1180/0009855054020165 ◽

2005 ◽

Vol 40 (2) ◽

pp. 191-203 ◽

Cited By ~ 15

Author(s):

F. Khormali ◽

A. Abtahi ◽

H. R. Owliaie

Keyword(s):

Electron Microscopy ◽

Upper Cretaceous ◽

Sedimentary Rocks ◽

X Ray Diffraction ◽

Humid Climate ◽

X Ray ◽

Late Mesozoic ◽

Southern Iran ◽

Transmission Electron

AbstractClay minerals of calcareous sedimentary rocks of southern Iran, part of the old Tethys area, were investigated in order to determine their origin and distribution, and to reconstruct the palaeoclimate of the area. Chemical analysis, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and thin-section studies were performed on the 16 major sedimentary rocks of the Fars and Kuhgiluyeh Boyerahmad Provinces.Kaolinite, smectite, chlorite, illite, palygorskite and illite-smectite interstratified minerals were detected in the rocks studied. The results revealed that detrital input is possibly the main source of kaolinite, smectite, chlorite and illite, whilein situneoformation during the Tertiary shallow saline and alkaline environment could be the dominant cause of palygorskite occurrences in the sedimentary rocks.The presence of a large amount of kaolinite in the Lower Cretaceous sediments and the absence or rare occurrence of chlorite, smectite, palygorskite and illite are in accordance with the warm and humid climate of that period. Smaller amounts of kaolinite and the occurrence of smectite in Upper Cretaceous sediments indicate the gradual shift from warm and humid to more seasonal climate. The occurrence of palygorskite and smectite and the disappearance of kaolinite in the late Palaeocene sediments indicate the increase in aridity which has probably continued to the present time.

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A critical look at the Wallace-Bott hypothesis in fault-slip analysis

BSGF - Earth Sciences Bulletin ◽

10.2113/gssgfbull.184.4-5.299 ◽

2013 ◽

Vol 184 (4-5) ◽

pp. 299-306 ◽

Cited By ~ 25

Author(s):

Richard J. Lisle

Keyword(s):

Shear Stress ◽

Maximum Shear Stress ◽

Fault Slip ◽

Shear Stresses ◽

Homogeneous State ◽

Slip Direction ◽

Fault Surface ◽

State Of Stress ◽

Simultaneous Movement

AbstractThe assumption is widely made that slip on faults occurs in the direction of maximum resolved shear stress, an assumption known as the Wallace-Bott hypothesis. This assumption is used to theoretically predict slip directions from known in situ stresses, and also as the basis of palaeostress inversion from fault-slip data. This paper examines different situations in relation to the appropriateness of this assumption. Firstly, it is shown that the magnitude of the shear stress resolved within a plane is a function with a poorly defined maximum direction, so that shear stress values greater than 90% of the maximum occur within a wide angular range (± 26°) degrees. The situation of simultaneous movement on pairs of faults requires slip on each fault to be parallel to their mutual line of intersection. However, the resolved shear stresses arising from a homogeneous state of stress do not accord with such a slip arrangement except in the case of pairs of perpendicular faults. Where fault surfaces are non-planar, the directions of resolved shear stress in general give, according to the Wallace-Bott hypothesis, a set of slip directions of rigid fault blocks, which is generally kinematically incompatible. Finally, a simple model of a corrugated fault suggests that any anisotropy of the shear strength of the fault such as that arising from fault surface topography, can lead to a significant angular difference between the directions of maximum shear stress and the slip direction.These findings have relevance to the design of procedures used to estimate palaeostresses and the amount of data required for this type of analysis.

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