Статті в журналах: "Stress-Dilatancy Relation"

1

Xiao, Yang, and Chandrakant S. Desai. "General Stress–Dilatancy Relation for Granular Soils." Journal of Geotechnical and Geoenvironmental Engineering 142, no. 4 (April 2016): 02816001. http://dx.doi.org/10.1061/(asce)gt.1943-5606.0001473.

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2

Gutierrez, Marte, and Jianfeng Wang. "Non-coaxial version of Rowe’s stress-dilatancy relation." Granular Matter 11, no. 2 (January 23, 2009): 129–37. http://dx.doi.org/10.1007/s10035-008-0124-0.

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3

Wong, Colin L. Y. "A normalizing relation for granular materials." Canadian Geotechnical Journal 27, no. 1 (February 1, 1990): 68–78. http://dx.doi.org/10.1139/t90-007.

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It is hypothesized that a normalized shear stress – strain curve for granular materials can be obtained by accounting fully for the effects of volume change. In this sense, volume change behavior is a factor that controls the shear stress – strain behavior of a granular material. This hypothesis is applied to Rowe's stress-dilatancy theory to include slip, rolling, rearrangement, and crushing strains, and a theoretical normalizing relation is obtained. The relation is demonstrated to be reasonably correct for the published test data utilized in this study. Differing fabrics of a granular material at the same void ratio can be corrected for by the normalizing relation. The hypothesis is also applied to simple shear behavior and an empirical normalizing relation is obtained.On the basis of the success of the normalizing relation, it is suggested that the volume change rate at 4% axial strain may be, in relation to shear behavior, a more appropriate characterizing parameter than void ratio. However, owing to the long-standing use and acceptance of void ratio, the concept of a reference void ratio, determined by specific sample preparation and testing procedures, is introduced as a characterizing parameter for granular materials. Key words: volume change, dilatancy, normalization, fabric, stress, strain, deformation, sand, granular material.

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4

Tafili, Merita, Carlos Grandas Tavera, Theodoros Triantafyllidis, and Torsten Wichtmann. "On the Dilatancy of Fine-Grained Soils." Geotechnics 1, no. 1 (August 31, 2021): 192–215. http://dx.doi.org/10.3390/geotechnics1010010.

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A new evaluation method for the dilatancy of fine-grained soils based on monotonic and cyclic undrained triaxial tests has been established using two elasticity approaches: isotropic and transverse isotropic hypoelasticity. The evaluation of two clays, Kaolin and Lower Rhine Clay, with the new method also shows that the dilatancy of fine-grained soils is dependent on the stress ratio, the void ratio, and the straining direction along with the intrinsic material parameters. Similar to sand, we can observe a Phase Transformation Line beyond which further shearing induces a volume increase. A generalization of the Taylor dilatancy rule from direct shear to multiaxial space is established, and an extension accounting for the behaviour of soft soils is proposed. We formulate a simple hypoplastic constitutive relation with a modified flow rule that reproduces the observed dilatant as well as contractant behaviour. Some simulations of monotonic as well as cyclic tests prove the accurate performance of the proposed dilatancy relation.

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5

Wan, R. G., and P. J. Guo. "Effect of microstructure on undrained behaviour of sands." Canadian Geotechnical Journal 38, no. 1 (February 1, 2001): 16–28. http://dx.doi.org/10.1139/t00-088.

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This paper presents a mathematical modelling of the effects of initial fabric on the mechanical behaviour of sand. A stress-dilatancy model that incorporates microstructural aspects of sand is hereby obtained while writing energy conservation for an ensemble of particles over a representative elementary volume at micro- and macro-scales. The resulting stress-dilatancy model, when used within an elastoplastic framework, successfully reproduces certain aspects of sand behaviour that are reflective of its microstructure under both drained and undrained conditions. The role of microstructure in relation to the characterization of steady, quasi-steady, and phase-transformation states is discussed within the framework of the model. Numerical simulations obtained from the proposed model are generally very consistent with experimental observations and provide insightful information.Key words: sand, liquefaction, fabric, dilatancy, constitutive laws, granular materials, plasticity.

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6

Marone, Chris. "A note on the stress-dilatancy relation for simulated fault gouge." Pure and Applied Geophysics PAGEOPH 137, no. 4 (1991): 409–19. http://dx.doi.org/10.1007/bf00879042.

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7

Dai, Bing, Guoyan Zhao, Longjun Dong, and Chen Yang. "Mechanical Characteristics for Rocks under Different Paths and Unloading Rates under Confining Pressures." Shock and Vibration 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/578748.

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To investigate mechanical characteristics of rocks under different unloading conditions, triaxial tests are carried out with initial confining pressures of 10, 20, and 30 MPa and unloading rates of 0.05~1 MPa/s in three stress paths. Results show that the increment of axial strain is far less than that of the lateral strain. The unloading rates of confining pressures have less influence on variation of strain and lateral increment in path I. The variation of axial increment strain in the same time is slightly larger than the variation of lateral increment; D-value is influenced by unloading rates of confining pressures in path II. The variation of axial strain increment decreases firstly and then increases with the variation of confining pressures. The relation decreases and then increases with unloading rates increases in path III. The dilatancy angle decreases with initial confining pressures increases. The vary rates of dilatancy angle from initial point of dilatancy angle to peak point of dilatancy angle increase with the unloading rates of confining pressures. In the same rates, the vary rates of dilatancy angle from the initial point of the dilatancy angle to peak point of the dilatancy angle in path I are greater than those in path II.

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8

Szypcio, Zenon. "Relation between the Friction Angle of Sand at Triaxial Compression and Triaxial Extension and Plane Strain Conditions." Geosciences 10, no. 1 (January 14, 2020): 29. http://dx.doi.org/10.3390/geosciences10010029.

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The strength of sand is usually characterized by the maximum value of the secant friction angle. The friction angle is a function of deformation mode, density, and stress level and is strongly correlated with dilatancy at failure. Most often, the friction angle is evaluated from results of conventional compression tests, and correlation between the friction angle of sand at triaxial compression and triaxial extension and plane strain conditions is a vital problem of soil mechanics. These correlations can be obtained from laboratory test results. The failure criteria for sand presented in literature also give the possibility of finding correlations between friction angles for different deformation modes. The general stress-dilatancy relationship obtained from the frictional state concept, with some additional assumptions, gives the possibility of finding theoretical relationships between the friction angle of sand at triaxial compression and triaxial extension and plane strain conditions. The theoretically obtained relationships presented in the paper are fully consistent with theoretical and experimental findings of soil mechanics.

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9

Iai, Susumu. "A New Look at the Stress Dilatancy Relation in Cam-Clay Model." Soils and Foundations 34, no. 2 (June 1994): 1–12. http://dx.doi.org/10.3208/sandf1972.34.2_1.

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10

Bartelt, Perry, and Othmar Buser. "The relation between dilatancy, effective stress and dispersive pressure in granular avalanches." Acta Geotechnica 11, no. 3 (May 21, 2016): 549–57. http://dx.doi.org/10.1007/s11440-016-0463-7.

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11

Alonso-Marroquin, Fernando, Hans Muhlhaus, and Hans Herrmann. "Micromechanical investigation of soil plasticity using a discrete model of polygonal particles." Theoretical and Applied Mechanics 35, no. 1-3 (2008): 11–28. http://dx.doi.org/10.2298/tam0803011a.

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The mechanical behavior of soils has been traditionally described using continuum-mechanics-based models. These are empirical relations based on laboratory tests of soil specimens. The investigation of the soils at the grain scale using discrete element models has become possible in recent years. These models have provided valuable understanding of many micromechanical aspects of soil deformation. The aim of this work is to draw together these two approaches in the investigation of the plastic deformation of non-cohesive soils. A simple discrete element model has been used to evaluate the effect of anisotropy, force chains, and sliding contacts on different aspects of soil plasticity: dilatancy, shear bands, ratcheting etc. The discussion of these aspects raises important questions such as the width of shear bands, the origin of the stress-dilatancy relation, and the existence of a purely elastic regime in the deformation of granular materials.

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12

Li, F. Z., and J. Pan. "Plane-Strain Crack-Tip Fields for Pressure-Sensitive Dilatant Materials." Journal of Applied Mechanics 57, no. 1 (March 1, 1990): 40–49. http://dx.doi.org/10.1115/1.2888321.

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Plane-strain crack-tip stress and strain fields are presented for materials exhibiting pressure-sensitive yielding and plastic volumetric deformation. The yield criterion is described by a linear combination of the effective stress and the hydrostatic stress, and the plastic dilatancy is introduced by the normality flow rule. The material hardening is assumed to follow a power-law relation. For small pressure sensitivity, the plane-strain mode I singular fields are found in a separable form similar to the HRR fields (Hutchinson, 1968a, b; Rice and Rosengren, 1968). The angular distributions of the fields depend on the material-hardening exponent and the pressure-sensitivity parameter. The low-hardening solutions for different degrees of pressure sensitivity are found to agree remarkably with the corresponding perfectly-plastic solutions. An important aspect of the effects of pressure-sensitive yielding and plastic dilatancy on the crack-tip fields is the lowering of the hydrostatic stress and the effective stress directly ahead of the crack tip, which may contribute to the experimentally-observed enhancement of fracture toughness in some ceramic and polymeric composite materials.

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13

ZHANG, J., and R. SALGADO. "Stress–dilatancy relation for Mohr–Coulomb soils following a non-associated flow rule." Géotechnique 60, no. 3 (March 2010): 223–26. http://dx.doi.org/10.1680/geot.8.t.039.

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14

Hirata, Momoko, Jun Muto, and Hiroyuki Nagahama. "Experimental analysis on Rowe’s stress-dilatancy relation and frictional instability of fault gouges." Episodes 37, no. 4 (December 1, 2014): 303–7. http://dx.doi.org/10.18814/epiiugs/2014/v37i4/010.

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15

Tun Tun, Win, Tomotaka Sato, Hirotaka Saito, and Yuji Kohgo. "Mechanical properties and stress–dilatancy relationships of unsaturated soil under various cyclic loading conditions." Acta Geotechnica 15, no. 7 (December 26, 2019): 1799–813. http://dx.doi.org/10.1007/s11440-019-00908-5.

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AbstractMost studies investigating the effect of cyclic loading on soil properties have been conducted for saturated soils. Embankments such as fill dams, roads and railways are usually constructed by unsaturated geo-materials and retained under unsaturated conditions during their in-service periods. Then when the stabilities of the embankments against dynamic motions such as earthquakes and traffic loads are evaluated, it is necessary to account for the cyclic properties of unsaturated soils. However, there are few studies investigating mechanical properties of unsaturated soils under cyclic loadings. There are two objectives in this paper. One objective is to investigate cyclic properties of an unsaturated silt under various cyclic loading conditions, while the other is to investigate the stress–dilatancy relationships; the relation of plastic strain increment ratio, − dεvp/dγp, versus stress ratio, q/p′; and to derive the plastic potential function of the unsaturated silt. Cyclic triaxial compression tests under various loading conditions were performed using the unsaturated silt. The material used is an artificial silty soil named DL clay. It was found from the series of the tests that the stiffness of the soil increased with an increase in suction and the number of cyclic loadings. The total volume reductions in the specimens decreased with an increase in suction. When the numbers of cyclic loadings and suction increased, the dilation also increased. Each unique stress–dilatancy relationship could be found in both loading and unloading processes. The relationships were similar to those of saturated soils under cyclic loadings. A unique plastic potential function could also be derived from the stress–dilatancy relationships.

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16

Tahir, Muhammad, and Adeel Ahmad. "Impact of pseudoplaticity and dilatancy of fluid on peristaltic flow and heat transfer: Reiner-Philippoff fluid model." Advances in Mechanical Engineering 12, no. 12 (December 2020): 168781402098118. http://dx.doi.org/10.1177/1687814020981184.

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The objective of this article is to investigate the impact of pseudoplaticity and dilatancy of fluid on peristaltic flow and heat transfer of non-Newtonian fluid in a non-uniform asymmetric channel. The mathematical-model incorporates the non-linear implicit stress deformation relation using the classical Reiner-Philippoff viscosity model, which is one of the very few non-Newtonian models exhibiting all the pseudoplastic, dilatant and Newtonian behaviors. The governing equations for the peristaltic flow and heat transfer of Reiner-Philippoff fluid are modeled using the low Reynolds-number and long wavelength approximation. Results of the study are presented graphically to discuss the impact of pseudoplaticity and dilatancy of fluid on the velocity, pressure gradient, bolus movement and temperature profile. The article is concluded with key observations that by increasing the value of the Reiner-Philippoff fluid parameter the velocity of fluid increase at the center of the channel and decreases near the boundaries of the channel. Effects of the shear stress parameter are opposite on pseudoplastic and dilatants fluid. By increasing the value of the shear stress parameter the velocity of the pseudoplastic fluid increases near the center of the channel, whereas the velocity of dilatants fluid decreases.

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17

Yildiz, Anil, Frank Graf, and Sarah M. Springman. "Volume change behavior of root-permeated soils under partially saturated conditions." E3S Web of Conferences 195 (2020): 01007. http://dx.doi.org/10.1051/e3sconf/202019501007.

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Vegetation, particularly roots, serves different functions in relation to increased shear strength under saturated and partially saturated conditions. Quantification of mechanical contribution of roots due to their tensile strength, and relationships of various vegetation parameters and plant-induced suction, as well as shear strength, have been widely studied. Although shear strength is directly related to the volume change characteristics of soil, dilative or contractive behaviour of root-permeated soils has not been of significant interest so far. This study investigates how volume change during shearing is related to the hydrological and mechanical characteristics of vegetated soils relevant to slope stability and shear strength of root-permeated soils under partially saturated conditions. Direct shear tests, on specimens planted with a mixture of species from different plant functional groups, were performed with an Inclinable Large-scale Direct Shear Apparatus (ILDSA). Matric suctions were monitored throughout the test with tensiometers. Vertical and horizontal displacement graphs were plotted to investigate the volume change behaviour. Maximum dilatancy angle was found to be positively correlated with plant-induced suction and net normalised stress, both of which were linked to root biomass and the root:shoot ratio. It was found that maximum dilatancy is controlled by matric suction and net normal stress.

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18

Tong, Chen-Xi, Hong-Wei Liu, and Hai-Chao Li. "Constitutive Modeling of Normally and Over-Consolidated Clay with a High-Order Yield Function." Mathematics 10, no. 9 (April 20, 2022): 1376. http://dx.doi.org/10.3390/math10091376.

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In this paper, a simple sub-loading yield surface model for both normally consolidated and over-consolidated clay is proposed with emphasis on the effect of the yield surface shape. Compared with the modified Cam-clay model, only one additional material parameter is introduced to reflect geometry features of the yield surface. A higher-order stress–dilatancy relation is given in the current study, leading to a new yield function capable of offering an adequate description of the yield surface of soil samples in the p–q plane. By introducing the concept of the sub-loading yield surface and the unified hardening parameter, the proposed model can capture the main features of the over-consolidated clay with dilatancy and strain-softening behavior and the main features of the normally consolidated clay with contraction and strain-hardening behavior. The results show that adjusting the yield surface leads to more accurate predictions than the modified Cam-clay model. The proposed model can also reasonably describe its mechanical behavior for clay samples.

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19

Zhang, An, Mingjing Jiang, and Wenhao Du. "Three-dimensional DEM investigation of the stress-dilatancy relation of grain-cementing type methane hydrate-bearing sediment." Petroleum 7, no. 4 (December 2021): 477–84. http://dx.doi.org/10.1016/j.petlm.2021.10.001.

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20

Qi, Yujie, Buddhima Indraratna, and Jayan S. Vinod. "Behavior of Steel Furnace Slag, Coal Wash, and Rubber Crumb Mixtures with Special Relevance to Stress–Dilatancy Relation." Journal of Materials in Civil Engineering 30, no. 11 (November 2018): 04018276. http://dx.doi.org/10.1061/(asce)mt.1943-5533.0002459.

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21

Sun, De An, Wen Xiong Huang, Dai Chao Sheng, and Haruyuki Yamamoto. "An Elastoplastic Model for Granular Materials Exhibiting Particle Crushing." Key Engineering Materials 340-341 (June 2007): 1273–78. http://dx.doi.org/10.4028/www.scientific.net/kem.340-341.1273.

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A practical elastoplastic constitutive model for granular materials is presented. And the model is suitable for description of the material behaviour for a wide range of stresses, including those sufficient to cause particle crushing. With a limited number of model parameters, the model can predict the confining-pressure dependent stress-strain relation and shear strength of granular materials in three-dimensional stresses, especially of variation of shear strength and dilatancy characteristics due to particle crushing under high confining pressure. The model parameters, which have clear physical meanings, can be determined from the results of isotropic compression test and conventional triaxial compression tests. The model performance is demonstrated for triaxial compression tests of a sand for a wide range of the confining-pressure from 0.2MPa to 8.0MPa.

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22

Nemat-Nasser, Sia. "Phenomenological Theories of Elastoplasticity and Strain Localization at High Strain Rates." Applied Mechanics Reviews 45, no. 3S (March 1, 1992): S19—S45. http://dx.doi.org/10.1115/1.3121388.

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In this paper certain fundamental concepts underlying the phenomenological theories of elastic-plastic deformations at finite strains and rotations are presented, and some of the commonly discussed theories are summarized, emphasizing the constitutive parameters which influence strain localization and material instability often observed in finite deformation of ductile materials. Particular attention is paid to the thermodynamic basis of inelastic deformation. Conditions for the existence of inelastic potentials are discussed. The results are presented in terms of a general material strain and its conjugate stress, and then specialized for particular applications, emphasizing quantities and theories which are reference- and strain measure-independent. Rate-independent and rate-dependent elastoplasticity relations are developed, starting from a finite deformation version of the J2-plasticity with isotropic and kinematic hardening, and leading to theories which include dilatancy, pressure sensitivity, frictional effects, and the noncoaxiality of the plastic strain and the stress deviator. A class of commonly used deformation plasticity theories is then examined and its relation to nonlinear elasticity is discussed. The question of plastic spin, and its relation to the decomposition of the deformation gradient into elastic and plastic constituents, is reviewed in some detail, and it is shown that this decomposition yields explicit relations which uniquely define all spins in terms of the velocity gradient and the elastic and plastic deformation rates, hence requiring no additional constitutive relations for the plastic spin. The phenomenon of strain localization at high strain rates is illustrated and discussed, and a series of numerical results are given. Finally, a recent breakthrough in elastoplastic explicit computational algorithms for large-strain, large-strain-rate problems is briefly reviewed.

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23

Wu, Ke, Ming Yue Ma, and Dong Xue Hao. "Study on Grouting Pressure of Splitting Grouting Based on Cylindrical Expansion Considering Large Strain." Advanced Materials Research 378-379 (October 2011): 288–91. http://dx.doi.org/10.4028/www.scientific.net/amr.378-379.288.

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Anti-seepage reinforcement technology of splitting grouting to improve the stability of dam, has been an effective reinforcement method in the field of dam reinforcement. Based on the extended SMP criterion and stress-dilatancy relation considering large strain, the governing equations of axisymmetric problem in the plane strain condition and the partial differential equations for the boundary-value problem of cavity expansion in frictional cohesive soils were established. Then, the early phase of splitting grouting is regarded as the plane strain question of cylindrical expansion infinite soil. Under initial grouting pressure, the soil body was supposed as ideal elastic mass. However, the soil body was supposed to generate plastic damage considering large strain with the increase of grouting pressure and submit the extended spatial mobilization plane theory. Solutions of radial and hoop stresses and strains around the grouting cavity were obtained by recursive computations. Furthermore, the influence of damage softening parameter, cohesion and friction angle was examined by a parametric study.

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24

Spagnoli, Andrea, Andrea Carpinteri, and Michele Terzano. "Crack shielding in non-planar and frictional discontinuities under mixed-mode loading." MATEC Web of Conferences 300 (2019): 15003. http://dx.doi.org/10.1051/matecconf/201930015003.

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In this paper, a two-dimensional model to describe the non-planar features of crack morphologies is presented. The model accounts for frictional tractions along the crack surfaces by considering an elastic-plastic-like constitutive interface law. Dilatancy effect due to crack roughness is described by the model, leading to a Mode I/II coupling between displacements and tractions along the crack surfaces. The non-linear solution of the rough and frictional crack under general remote scenarios is obtained using the Distributed Dislocation Technique (DDT). By considering a linear piecewise periodic profile of the interface crack, the influence of roughness and friction of interface cracks is examined in relation to both the resulting near-tip stress field and the fracture resistance under monotonic mixed-mode loading. The present model is able to quantify the increase of the fracture resistance due to roughnessand friction-induced crack tip shielding and to correlate it with a dimensionless crack size parameter.

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25

Yan, Xiaoyu, Wei Wang, Xiaojun Liu, Jimin Xu, Lihong Zhu, and Bingxun Yang. "Using FEM to study the frictional instability induced by third-body particles confined in frictional interface." Industrial Lubrication and Tribology 72, no. 10 (June 1, 2020): 1239–44. http://dx.doi.org/10.1108/ilt-12-2019-0544.

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Purpose A finite element method (FEM) model of the frictional behavior of two rough surfaces with a group of third-body particles confined by the surface asperities is established. By monitoring the stress distribution, friction force and the displacement of the surfaces, how the frictional instability is induced by these particles is studied. This modeling job aims to explore the relation between the meso-scale behavior and the macro-scale frictional behavior of these particles. Design/methodology/approach By using FEM, a 2D model of two frictional rough surfaces with a group of elastic or elasto-plastic particles confined by surface asperities is established. The Mises stress, macro friction force and displacements of elements are monitored during compressing and shearing steps. Findings The macro friction coefficient is more stable under higher pressure and smaller under higher shearing speed. The dilatancy of the interface is caused by the elevation effect of the particles sheared on the peak of the lower surface, particles collision and third body supporting. The combined effect of particles motion and surface–surface contact will induce high-frequency displacements of surface units in restricted direction. Originality/value Previous studies about third-body tribology are mainly concentrated on the frictional behavior with large number of particles distributed homogeneously across the interface, but this paper focuses on the behavior of third-body particles confined by surface asperities. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2019-0544/

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26

Iverson, Richard M., and David L. George. "Discussion of “The relation between dilatancy, effective stress and dispersive pressure in granular avalanches” by P. Bartelt and O. Buser (DOI: 10.1007/s11440-016-0463-7)." Acta Geotechnica 11, no. 6 (October 17, 2016): 1465–68. http://dx.doi.org/10.1007/s11440-016-0502-4.

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27

Quiroga Flores, Alfredo, Rodolfo Giacomim Mendes de Andrade, Michèle Schubert Pfeil, Joaquim A. O. Barros, Ronaldo Carvalho Battista, Olga Maria Oliveira de Araújo, Ricardo Tadeu Lopes, and Romildo Dias Toledo Filho. "Relation between Shear Stresses and Flexural Tensile Stresses from Standardized Tests of Extracted Prismatic Specimens of an SFRC Bridge Girder." Materials 15, no. 23 (November 22, 2022): 8286. http://dx.doi.org/10.3390/ma15238286.

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Experimental research on the direct shear behavior of fiber-reinforced concrete is often carried out using prisms molded with specific dimensions for a standardized test. However, the flow of fresh concrete in these molds can be different than in the case of a full-scale structural element. This is important considering that the flow direction highly influences the distribution and orientation of fibers. In addition, most of the studies did not relate their shear results to other mechanical properties. In contrast, this study attempted to deepen the experimental knowledge of the crack propagation of a steel fiber-reinforced concrete (SFRC) used in a full-scale prototype of a bridge box girder built in the laboratory. Prismatic specimens were sawn from webs and top flanges of this prototype. Serving as references, additional specimens were molded in wooden boxes. In a previous study of our research group, both had been tested under a three-point notched bending configuration maintaining test conditions proportional to the EN14651 specifications. From each of the previously flexurally tested specimens, two prismatic specimens suitable for the Fédération Internationale de la Précontrainte (FIP) shear test setup were extracted by adopting a cutting methodology that avoided the damage induced by the flexural tests to be part of the FIP specimens. These FIP specimens were tested in almost pure shear loading conditions for assessing the performance of SFRC. Computer tomography images and photos of the shear failure faces were used to determine the distribution and density of fibers. The results demonstrated that the peak loads were proportional to the fiber density at the shear failure section. Assuming that the SFRC conditions of the webs were representative of a common batching procedure in the construction industry, the results from the tests in specimens extracted from these webs were adopted to establish shear stress/flexural tensile stress ratios vs. crack mouth opening displacement curves. The curves belonging to cross-sections of a similar fiber density in the shear and flexural cases allowed for the proposal of a normalized crack-dilatancy relation composed of three stages of the crack propagation. In addition, a trilinear crack width–slip relation was established using the same set of specimens. The relevancy of this proposal is that the shear response can be estimated from a widely accepted standardized flexural test, which demands a simpler instrumentation and is also easier to execute than the shear setup.

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28

Szypcio, Zenon. "Stress-Dilatancy for Soils. Part II: Experimental Validation for Triaxial Tests." Studia Geotechnica et Mechanica 38, no. 4 (December 1, 2016): 59–65. http://dx.doi.org/10.1515/sgem-2016-0031.

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Abstract Different forms of the stress-dilatancy relations obtained based on the frictional theory for the triaxial condition are presented. The analysed test data show that the shear resistance of many soils is purely frictional. The angle Φ0 represents the resistance of the soil as a combined effect of sliding and particle rolling on the macro-scale during shear at the critical frictional state. The stress-plastic dilatancy relations differ not only for triaxial compression and extension but also for drained and undrained conditions. The experiment investigated shows the correctness of the frictional state theory in the triaxial condition.

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29

Been, Ken, and Michael Jefferies. "Stressdilatancy in very loose sand." Canadian Geotechnical Journal 41, no. 5 (September 1, 2004): 972–89. http://dx.doi.org/10.1139/t04-038.

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Virtually all investigation of liquefaction has used undrained tests, and it has become common to represent the undrained strength in terms of a collapse surface or collapse stress ratio described by an effective friction angle. A difficulty with undrained tests is that they only allow observation of the interaction of elastic and plastic strain because of the imposed boundary condition (i.e., no drainage or zero volume change), precluding a proper understanding of an effective stress criterion for maximum undrained strength. Drained triaxial tests do not suffer from this shortcoming, and stressdilatancy of dense sands in drained shear is well established as a fundamental aspect of sand behaviour, based on micromechanical considerations. It is particularly interesting to consider the stressdilatancy behaviour of very loose sands in the context of soil liquefaction. Although there are some data in the literature on loose sand behaviour in drained triaxial compression, the majority of data are actually for sands markedly denser than sands showing static liquefaction in undrained tests. This paper therefore reports some laboratory testing of very loose sands, together with comparative undrained liquefaction data, and compares the loose behaviour to that of dense sand. These data are reduced to stressdilatancy form so that the fundamental aspects of loose soil behaviour can be seen and compared to flow rules used in constitutive models. The stressdilatancy of very loose sand shows no limiting stress ratio markedly less than that of the critical state. Moreover, the stressdilatancy trends of very loose sand are the same as those of dense sand. There is no evidence of "structural collapse" of the particulate arrangement of very loose sands, contrary to speculation associated with collapse surfaces in the literature. Explanations of sand liquefaction must seek other physical explanations of the soil behaviour.Key words: sand, constitutive relations, plasticity, liquefaction.

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Pradhan, Tej B. S., Fumio Tatsuoka, and Yasuhiko Sato. "Experimental Stress-Dilatancy Relations of Sand Subjected to Cyclic Loading." Soils and Foundations 29, no. 1 (March 1989): 45–64. http://dx.doi.org/10.3208/sandf1972.29.45.

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Bartelt, Perry, and Othmar Buser. "Reply to “Discussion of “The relation between dilatancy, effective stress and dispersive pressure in granular avalanches” by P. Bartelt and O. Buser (DOI: 10.1007/s11440-016-0463-7)” by Richard Iverson and David L. George (DOI: 10.1007/s11440-016-0502-4)." Acta Geotechnica 11, no. 6 (October 20, 2016): 1469–73. http://dx.doi.org/10.1007/s11440-016-0503-3.

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32

Silvestri, Vincenzo. "Interpretation of pressuremeter tests in sand." Canadian Geotechnical Journal 38, no. 6 (December 1, 2001): 1155–65. http://dx.doi.org/10.1139/t01-045.

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This paper presents a method to obtain the constitutive relationships of sand from drained self-boring pressuremeter tests. Plane-strain conditions and Rowe's stressdilatancy theory are assumed to hold to determine stress and finite strain distributions and paths. The proposed method, which has been validated using both calibration chamber studies and field tests, appears to correctly render the response behaviour of relatively loose to dense sands.Key words: stressstrain relations, self-boring pressuremeter tests, sands, finite strains, stress distributions, paths.

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Tsegaye, Anteneh Biru, Thomas Benz, and Steinar Nordal. "Formulation of non-coaxial plastic dissipation and stress–dilatancy relations for geomaterials." Acta Geotechnica 15, no. 10 (May 18, 2020): 2727–39. http://dx.doi.org/10.1007/s11440-020-00968-y.

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Gutierrez, M., R. W. Lewis, and I. Masters. "Petroleum Reservoir Simulation Coupling Fluid Flow and Geomechanics." SPE Reservoir Evaluation & Engineering 4, no. 03 (June 1, 2001): 164–72. http://dx.doi.org/10.2118/72095-pa.

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Summary This paper presents a discussion of the issues related to the interaction between rock deformation and multiphase fluid flow behavior in hydrocarbon reservoirs. Pore-pressure and temperature changes resulting from production and fluid injection can induce rock deformations, which should be accounted for in reservoir modeling. Deformation can affect the permeability and pore compressibility of the reservoir rock. In turn, the pore pressures will vary owing to changes in the pore volume. This paper presents the formulation of Biot's equations for multiphase fluid flow in deformable porous media. Based on this formulation, it is argued that rock deformation and multiphase fluid flow are fully coupled processes that should be accounted for simultaneously, and can only be decoupled for predefined simple loading conditions. In general, it is shown that reservoir simulators neglect or simplify important geomechanical aspects that can impact reservoir productivity. This is attributed to the fact that the only rock mechanical parameter involved in reservoir simulations is pore compressibility. This parameter is shown to be insufficient in representing aspects of rock behavior such as stress-path dependency and dilatancy, which require a full tensorial constitutive relation. Furthermore, the pore-pressure changes caused by the applied loads from nonpay rock and the influence of nonpay rock on reservoir deformability cannot be accounted for simply by adjusting the pore compressibility. Introduction In the last two decades, there has been a strong emphasis on the importance of geomechanics in several petroleum engineering activities such as drilling, borehole stability, hydraulic fracturing, and production-induced compaction and subsidence. In these areas, in-situ stresses and rock deformations, in addition to fluid-flow behavior, are key parameters. The interaction between geomechanics and multiphase fluid flow is widely recognized in hydraulic fracturing. For instance, Advani et al.1 and Settari et al.2 have shown the importance of fracture-induced in-situ stress changes and deformations on reservoir behavior and how hydraulic fracturing can be coupled with reservoir simulators. However, in other applications, geomechanics, if not entirely neglected, is still treated as a separate aspect from multiphase fluid flow. By treating the two fields as separate issues, the tendency for each field is to simplify and make approximate assumptions for the other field. This is expected because of the complexity of treating geomechanics and multiphase fluid flow as coupled processes. Recently, there has been a growing interest in the importance of geomechanics in reservoir simulation, particularly in the case of heavy oil or bituminous sand reservoirs,3,4 water injection in fractured and heterogeneous reservoirs,5–7 and compacting and subsiding fields.8,9 Several approaches have been proposed to implement geomechanical effects into reservoir simulation. The approaches differ on the elements of geomechanics that should be implemented and the degree to which these elements are coupled to multiphase fluid flow. The objective of this paper is to illustrate the importance of geomechanics on multiphase flow behavior in hydrocarbon reservoirs. An extension of Biot's theory10 for 3D consolidation in porous media to multiphase fluids, which was proposed by Lewis and Sukirman,11 will be reviewed and used to clarify the issues involved in coupling fluid flow and rock deformation in reservoir simulators. It will be shown that for reservoirs with relatively deformable rock, fluid flow and reservoir deformation are fully coupled processes, and that such coupled behaviors cannot be represented sufficiently by a pore-compressibility parameter alone, as is done in reservoir simulators. The finite-element implementation of the fully coupled equations and the application of the finite-element models to an example problem are presented to illustrate the importance of coupling rock deformation and fluid flow. Multiphase Fluid Flow in Deformable Porous Media Fig. 1 illustrates the main parameters involved in the flow of multiphase fluids in deformable porous media and how these parameters ideally interact. The main quantities required to predict fluid movement and productivity in a reservoir are the fluid pressures (and temperatures, in case of nonisothermal problems). Fluid pressures also partly carry the loads, which are transmitted by the surrounding rock (particularly the overburden) to the reservoir. A change in fluid pressure will change the effective stresses following Terzaghi's12 effective stress principle and cause the reservoir rock to deform (additional deformations are induced by temperature changes in nonisothermal problems). These interactions suggest two types of fluid flow and rock deformation coupling:Stress-permeability coupling, where the changes in pore structure caused by rock deformation affect permeability and fluid flow.Deformation-fluid pressure coupling, where the rock deformation affects fluid pressure and vice versa. The nature of these couplings, specifically the second type, are discussed in detail in the next section. Stress-Permeability Coupling This type of coupling is one where stress changes modify the pore structure and the permeability of the reservoir rock. A common approach is to assume that the permeability is dependent on porosity, as in the Carman-Kozeny relation commonly used in basin simulators. Because porosity is dependent on effective stresses, permeability is effectively stress-dependent. Another important effect, in addition to the change in the magnitude of permeability, is on the change in directionality of fluid flow. This is the case for rocks with anisotropic permeabilities, where the full permeability tensor can be modified by the deformation of the rock. Examples of stress-dependent reservoir modeling are given by Koutsabeloulis et al.6 and Gutierrez and Makurat.7 In both examples, the main aim of the coupling is to account for the effects of in-situ stress changes on fractured reservoir rock permeability, which in turn affect the fluid pressures and the stress field. The motivation for the model comes from the field studies done by Heffer et al.5 showing that there is a strong correlation between the orientation of the principal in-situ stresses with the directionality of flow in fractured reservoirs during water injection. There is also growing evidence that the earth's crust is generally in a metastable state, where most faults and fractures are critically stressed and are on the verge of further slip.13 This situation will broaden the range of cases with strong potential for coupling of fluid flow and deformation.

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Oncken, O., S. Angiboust, and G. Dresen. "Slow slip in subduction zones: Reconciling deformation fabrics with instrumental observations and laboratory results." Geosphere 18, no. 1 (November 22, 2021): 104–29. http://dx.doi.org/10.1130/ges02382.1.

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Abstract Cataclasites are a characteristic rock type found in drill cores from active faults as well as in exposed fossil subduction faults. Here, cataclasites are commonly associated with evidence for pervasive pressure solution and abundant hydrofracturing. They host the principal slip of regular earthquakes and the family of so-called slow earthquakes (episodic slip and tremor, low to very low frequency earthquakes, etc.). Slip velocities associated with the formation of the different types of cataclasites and conditions controlling slip are poorly constrained both from direct observations in nature as well as from experimental research. In this study, we explore exposed sections of subduction faults and their dominant microstructures. We use recently proposed constitutive laws to estimate deformation rates, and we compare predicted rates with instrumental observations from subduction zones. By identifying the maximum strain rates using fault scaling relations to constrain the fault core thickness, we find that the instrumental shear strain rates identified for the family of “slow earthquakes” features range from 10−3s−1 to 10−5s−1. These values agree with estimated rates for stress corrosion creep or brittle creep possibly controlling cataclastic deformation rates near the failure threshold. Typically, pore-fluid pressures are suggested to be high in subduction zones triggering brittle deformation and fault slip. However, seismic slip events causing local dilatancy may reduce fluid pressures promoting pressure-solution creep (yielding rates of <10−8 to 10−12s−1) during the interseismic period in agreement with dominant fabrics in plate interface zones. Our observations suggest that cataclasis is controlled by stress corrosion creep and driven by fluid pressure fluctuations at near-lithostatic effective pressure and shear stresses close to failure. We posit that cataclastic flow is the dominant physical mechanism governing transient creep episodes such as slow slip events (SSEs), accelerating preparatory slip before seismic events, and early afterslip in the seismogenic zone.

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Rahimi, Mojtaba. "Review of Proposed Stress-dilatancy Relationships and Plastic Potential Functions for Uncemented and Cemented Sands." Journal of Geological Research 1, no. 2 (September 30, 2019). http://dx.doi.org/10.30564/jgr.v1i2.864.

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Stress-dilatancy relationship or plastic potential function are crucial components of every elastoplastic constitutive model developed for sand or cemented sand. This is because the associated flow rule usually does not produce acceptable outcomes for sand or cemented sand. Many formulas have been introduced based on the experimental observations in conventional and advanced plasticity models in order to capture ratio of plastic volumetric strain increment to plastic deviatoric strain increment (i.e. dilatancy rate). Lack of an article that gathers these formulas is clear in the literature. Thus, this paper is an attempt to summarize plastic potentials and specially stress-dilatancy relations so far proposed for constitutive modelling of cohesionless and cemented sands. Stress-dilatancy relation is usually not the same under compression and extension conditions. Furthermore, it may also be different under loading and unloading conditions. Therefore, the focus in this paper mainly places on the proposed stress-dilatancy relations for compressive monotonic loading. Moreover because plastic potential function can be calculated by integration of stress-dilatancy relationship, more weight is allocated to stress-dilatancy relationship in this research.

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37

"Note on the stress-dilatancy relation for simulated fault gouge." International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 30, no. 1 (February 1993): 8. http://dx.doi.org/10.1016/0148-9062(93)90234-5.

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38

Taibi, Amine, Youcef Mahmoudi, Abdellah Cherif Taiba, Hamou Azaiez, and Mostefa Belkhatir. "Fly Ash Effects on the Stress-Dilatancy Relation of Coarse Soils: Particle Morphology Role." Geotechnical and Geological Engineering, March 17, 2023. http://dx.doi.org/10.1007/s10706-023-02412-w.

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Gudehus, Gerd, Christof Lempp, Christian Scheffzük, Birgit I. Műller, and Frank R. Schilling. "Depletion-induced seismicity in NW-Germany: lessons from comprehensive investigations." Acta Geotechnica, July 5, 2022. http://dx.doi.org/10.1007/s11440-022-01513-9.

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AbstractEvaluating various investigations for north-German gas fields, we discuss past and actual evolutions of the rock fabric in the light of dilatant driven and spontaneous contractant critical phenomena. Features of the latter were discovered by multi-stage triaxial tests with water-saturated sandstone samples and were similarly observed around the gas fields. A Mohr–Coulomb condition with quasi-local stress components ($${\hat{\sigma }}'_1$$ σ ^ 1 ′ and $${\hat{\sigma }}'_3$$ σ ^ 3 ′ ), and variable parameters $$\phi $$ ϕ ’ and $${{\hat{c}}}'$$ c ^ ′ , can capture successive critical states of the solid fabric. The implied driven dilatation up to a collapse with contraction is captured by a stress-dilatancy relation. Fractal patterns of shear bands (faults) dominate if the smallest principal stress $${\hat{\sigma }}'_3$$ σ ^ 3 ′ exceeds $${{\hat{c}}}'$$ c ^ ′ , otherwise cracks dominate and can lead to a rockburst. Triaxial tests with X-ray attenuation, seismometry including the splitting of shear waves and/or neutron beam diffraction contribute to clarification and validation. Seismic early warning and calculation models for various geotechnical operations with dominating faults can thus be improved, but the task is more difficult for rockbursts.

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Yan, Xiaoyu, Wei Wang, Xiaojun Liu, Guiqin Zhu, and Lihong Zhu. "Using a coupled FEM-DEM method to study the nonlinear phenomena of third-body behavior." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, June 9, 2020, 135065012093198. http://dx.doi.org/10.1177/1350650120931982.

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Third-body lubrication is widely applied in the design of mechanical frictional pair, but the relation between the lubrication performance and third-body rheology is hardly focused on. In this paper, the behavior of two plates shearing granular third-body is modeled by a coupled FEM-DEM method to study the nonlinear phenomena during this process. The upper plate is modeled by FEM, while the third-body and lower plate are modeled by DEM. During the simulation, the upper plate compresses the granular third-body at a certain pressure. Then, the lower plate shears at a constant speed. The fluctuations of friction force and dilatancy phenomenon of clearance between two plates, which show strong nonlinearity over time, are studied over different external loads, shearing speeds, and elastic moduli. The nonlinear distributions of averaged stress and velocity across the height of third-body are also studied to further reveal the relation between the nonlinear phenomena and the discreteness of third-body. The perspective of the paper is that the coupled FEM-DEM method can elucidate the nonlinear nature of third-body by efficiently processing both the third-body rheology and first-body deformation.

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K. Baddari, G. A. Sobolev, A. D. Frolov, and A. V. Ponomarev. "An integrated study of physical precursors of failure in relation to earthquake prediction, using large scale rock blocks." Annals of Geophysics 42, no. 5 (October 18, 1999). http://dx.doi.org/10.4401/ag-3758.

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This paper is multi-analysis approach to rock failure using metric size rock samples. The use of large-scale models permits simulation of the seismic process (including internal rupture on several scales) and utilization of a dense network for observation of the spatial variations of several physical parameters. The experiments were performed both on solid rock blocks and on concrete blocks with artificial defects, which enabled simulation of internal shear fracture. The number of various precursors appears to rise up to failure, all of them clearly manifest at the stage of a rapid drop in the applied stress (unstable deformation). The experiment suggests that rocks under strain and prior to failure must be characterized by a heterogeneous field of strains. This means that the strain is distributed mosaically, dilatancy does not generate uniformly and areas where it occurs are likely to be structurally mosaic themselves. To reinforce the prediction of micro- and macrofailure, we have realized simultaneous processing of the obtained data, using sophisticated multidimensional orthogonal functions to represent the different precursors. The possibility to identify the early stages of microfailures and to predict the macrofailure by means of statistical complex parameters derived from data on local deformations, acoustic emissions, elastic waves velocities, electric resistivity and self electric potentials is shown. Despite a considerable dissimilarity in mechanical properties of granite basalt and concrete, the complex parameter proves morphologically identical. Parameter S1 reveals exponential rise up to failure in all cases, and parameter S2 is bay-shaped in form, which makes it more promising in terms of prognosis.

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Tsegaye, Anteneh Biru. "Cyclic stress–dilatancy relations and plastic flow potentials for soils based on hypothesis of complementarity of stress–dilatancy conjugates." Acta Geotechnica, December 19, 2022. http://dx.doi.org/10.1007/s11440-022-01764-6.

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AbstractSoil, rocks and rock masses dilate or compact when sheared, i.e., distortion necessitates volume change. This coupling between distortional strains and volumetric strains, described by stress–dilatancy theories, endows soils with manifestation of peculiar characteristics when they are subjected to shear. Stress–dilatancy theories have become central in describing the mechanical energy dissipation mechanism and further establishing flow rules in constitutive modelling of soils. The classical stress–dilatancy theories, such as Taylor's and Rowe's, are endowed with simplicity and descriptive power, but they were developed for describing the dilatancy behaviour of soils subjected to loading in shear (mobilizing away from isotropic stress state) and needed to be extended for describing plastic dissipation and shear-induced volumetric changes when soils are subjected to cyclic shear. In this paper, hypothesis of complementarity of stress–dilatancy conjugates is proposed as a unifying hypothesis for deriving stress–dilatancy relations for both loading in shear and unloading in shear. Then, plastic potential functions are derived based on the resulting stress–dilatancy relations. In so doing, the resulting stress–dilatancy relations and plastic potential functions are rendered with a quality to be used for the modelling of deformation behavior of soils subjected to both monotonic and cyclic shearing. The theoretical framework is applied first for plane strain and axisymmetric stress–strain conditions; and then extended for the general stress condition considering the Lode angle dependency of the shear strength of soils, using the multilaminate framework and applying the Matsuoka–Nakai spatial mobilized plane.

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"Experimental stress-dilatancy relations of sand subjected to cyclic loading." International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 26, no. 6 (December 1989): 296. http://dx.doi.org/10.1016/0148-9062(89)91506-4.

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Evesque, Pierre, and Christian Stefani. "Relationship Between Dilatancy, Stresses and Plastic Dissipation in a Granular Material with Rigid Grains." MRS Proceedings 291 (January 1, 1992). http://dx.doi.org/10.1557/proc-291-473.

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ABSTRACTBy considering a drained cohesionless granular sample made up of rigid grains and submitted to a triaxial test, we derive an equation relating the dilatancy K, the deviatoric stress q and the confining pressure p to the energy losses D plasticdue to plastic yielding. We demonstrate that the system is contracting (K ≤ 0) at q=0, when q is increasing and that spontaneous uncontrolled yielding begins occurring when dilatancy K is maximum. We also demonstrate the existence of the characteristic state introduced by Luong and Habib and the existence of the critical state of Schofield and Wroth. We give at last a method to determine the plastic losses during a triaxial cell test using the experimental data.

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