Fig 24 - uploaded by Nick Ryland Barton
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Generating shear-displacement-dilation behaviour predictions, for three different block sizes. Barton, 1982.
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Despite utilizing multi-discipline teams in petroleum and service companies, and despite the remarkable abilities of these same companies to produce petroleum in many forms and in highly adverse environments, there appears to be a misalignment between the geomechanics used, and rock mechanics, the latter apparently not used, judging by workshop pre...
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Strength and elastic properties of rocks have vital importance for the design of structures in several rock engineering projects. Additionally, these parameters are extensively used in numerical modelling to envisage the mechanical behavior of rock before failure and their relevance to geotechnical characteristics in slope stability. This study was...
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Abstract
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Citations
... However, the microscopic fracture law was not examined and requires further study. The roughness is a significant factor for the influence of joints on the mechanical behaviours of rock (Ge et al., 2014;Indraratna et al., 2014;Barton, 2016;Mohd-Nordin et al., 2016), the rough joint is not defined explicitly. Nowadays the problem was raised up to the table calling for an urgent solution. ...
... However, many laboratory and field test results show that the dilatancy of rock can lead to changes in the roughness of structural plane, so the yield behavior of the structural plane shows an indigenous nonlinear phenomenon [23][24][25][26]. The Barton-Bandis criterion is a strength criterion for describing the nonlinear shear behavior of the structural plane based on a large number of experimental results, and the parameters involved in the Barton-Bandis criterion have real physical significance, which can be measured conveniently and quickly [27]. ...
... The equivalent friction angle and cohesion can be obtained by substituting Equation (26) into Equations (24) and (25). ...
The structural plane plays a decisive role in the development processes of rockburst. In this paper, Barton-Bandis criterion of structural plane and its conversion relationship with Mohr-Coulomb criterion are discussed in detail. Firstly, when the structural plane obeys Barton-Bandis criterion, the value range of the dip angle of the structural plane when it is yield is deduced theoretically, and the yield function of the structural plane is proposed: F=sinA−2β+PsinA. The correctness of the theoretical derivation result is verified by a mapping method and numerical simulation method. Secondly, based on the result of theoretical derivation and assuming that rock obeys Mohr-Coulomb criterion, a fast identification method for the failure modes of rock mass is proposed. The failure modes of rock mass are divided into “no failure”, “failure along structural plane”, “failure along rock”, and “failure along both rock and structural plane”, and the correctness of the fast identification method is verified by numerical simulation. Finally, from the perspective of structural plane failure, a new method for converting Barton-Bandis criterion to Mohr-Coulomb criterion is proposed. Based on the yield of structural plane and relative error of displacement, the differences between the new method and existing conversion methods are compared. The results show that the yield condition determined by the new method is consistent with those determined by Barton-Bandis criterion, and the relative error of displacement is less than the tangent regression method and linear fitting method. In summary, the relevant methods and conclusions of this paper provide theoretical support and technical guidance for the mutual conversion between different criteria and the prediction and identification of rock mass failure modes in rockburst.
... There are many strength criterions for predicting the shear strength of the joint, and Barton shear strength criterion, as a nonlinear strength criterion, has been proposed and recognized by many scholars, and its accuracy has also been widely verified [23][24][25]. During shear process, the yield criterion of the elastic-plastic constitutive model adopts Barton strength criterion: ...
As a common geological structure, rock joints have a great influence on the mechanical properties and stability of rock mass engineering. The shear constitutive model of the rock joint and its calculation methods have played an important role in theoretical and experimental research. Most of the existing elastic–plastic shear constitutive models of the rock joint are simplified to linear form or only considering hardening behavior, while the shear test results show that the post-peak nonlinear softening curve is the most common form for shear curves. Therefore, based on Barton shear strength criterion, the shear stress softening is characterized by the change of the post-peak joint roughness coefficient (JRC), and an increment elastic–plastic constitutive model reflecting the shear stress softening is established. According to the constraint condition of constant normal stress, the increment model of the normal deformation with shear deformation is obtained. Based on principle of the implicit return mapping algorithm, an algorithm for the shear softening elastic–plastic constitutive model in the stress space is established. The applicability and rationality of the model and algorithm are verified by a large number of the joint shear experiment results under different conditions. The established elastic–plastic constitutive model provides an effective reference for correctly evaluating the shear deformation characteristics of the joint.
... As a result of this reason, the B-B criterion has preferred more for shear strength of discontinuities and slope stability analysis. Although some studies have criticized the use of the B-B criterion (Hong et al. 2008;Kulatilake et al. 1995), it is currently recommended and used by many researchers because of its ability to model the nonlinear behavior of rock joints (Barton 2016;Prassetyo et al. 2017;Sow et al. 2016). But even by considering the fact that the B-B criterion is currently the most realistic empirical criterion, it didn't supersede the linear M-C criterion yet. ...
One of the most common geological hazards in mining and civil projects is the occurrence of instability in the rock slopes. Rock slope behavior is mainly influenced by the presence of discontinuities in the rock masses. Therefore, the determination of shear strength parameters for these weak surfaces is of particular importance. There are various shear strength criteria for estimating the shear strength of discontinuities, which among them the Barton–Bandis criterion (B‒B criterion) and Mohr–Coulomb criterion (M‒C criterion) are the most widely used. Accurate estimation of shear strength properties does not only depend on the correct procedure of tests, but it requires an accurate and detailed explanation of test results. The uncertainty in the measured shear strength leads to many problems in the analyzing and designing of rock slopes. Therefore, to reduce the uncertainty and increase the accuracy of rock slopes analyzing, it is better to use probability methods. The probability distribution function can be assigned for each input parameter of the failure criterion. In this research, the results of the direct shear tests related to Azad pumped storage power plant project have been considered to estimate the shear strength properties of rock discontinuities. The results are divided into three groups based on the magnitude of the joint roughness coefficient (JRC). Shear strength for each group is estimated depending on the two most well-known criteria i.e., the B‒B criterion and the M‒C criterion. Further, the probability distribution functions (PDF) for each shear strength parameter are determined by @RISK software. Besides, the results of the empirical B‒B criterion are compared with the results of the direct shear tests for the three groups of rock joints. The confidence intervals associated with both criteria are estimated and compared together. The results showed that the overlapping of the confidence interval of the M‒C criterion with the confidence interval of B‒B criterion increases with increasing JRC of rock joint. The results show the B‒B criterion covers data of the direct shear test almost at low normal stress levels for different JRC groups too.
... For the shear strength of rock discontinuities the Q system can be used (Barton and Choubey, 1977;Barton, 2016). The failure criterion is expressed by: ...
... The mechanical properties of the bedding planes obtained are given in Table 12, including cohesion and peak and residual friction angles. The parameters JCS and JRC of the Q system (Barton, 2016) are also given as well as the applied pressures during tests (normal and peak and residual values). In-situ shear tests were performed at the Kurobe dam foundation site in Japan in basaltic formations (Rocha, 2013). ...
In recent years, the evaluation of geomechanical parameters in rock masses and particularly in soft rock masses has gone through significant improvements. New instruments and equipment for in situ and laboratory tests allow for a more accurate evaluation of the properties of soft rock masses. Advancements in data mining (DM) techniques allow for better tools for decision making. The combination of improved instrumentation and more powerful numerical techniques allow for a better characterization of the geomechanical parameters of rock masses. In this chapter, methodologies for deformability and strength evaluation are presented. Equipment that is frequently used for this is illustrated with emphasis on common techniques in situ and in the laboratory. Results of extensive testing on soft rocks are presented with emphasis on the testing of a very heterogeneous conglomerate rock mass at a dam site in Japan. Conclusions and recommendations are presented at the end of the chapter.
... Cross-Atlantic research (on non-linear description for rock joints) does not seem to be popular in geomechanics, despite 65% of remaining petroleum in naturally fractured reservoirs (NFR) with guaranteed non-linear behavior. See Barton, 2015 andBarton, 2016 for further discussion. Figure 10 The importance of variable frictional angles on rock slope stability (and indeed on slope deformation characteristics) are nicely illustrated by these early distinct element (μDEC) models which was a method developed by Cundall, and culminated in UDEC (UDEC-MC and UDEC-BB) and 3DEC-MC. ...
The term ‘characterisation’ will be used to describe methods of collection and interpretation of the physical attributes of the joints and other discontinuities, in other words those which control their mechanical and hydraulic properties, and the behaviour of jointed rock as an engineering medium. Rock discontinuities vary widely in terms of their origin (joints, bedding, foliation, faults/shears, etc.) and associated physical characteristics. They can be very undulating, rough or extremely planar and smooth,
tightly interlocked or open, filled with soft, soil-type inclusions or healed with hard materials. Therefore, when loaded in compression or shear, they exhibit large differences in the normal and shear deformabilityand strength, resulting in surface separation and therefore permeability. Such variability calls for innovative, objective and practical methods of joint characterisation for engineering purposes. The output must be quantitative and meaningful and the cost kept at reasonable levels. The practical methods to bedescribed will be biased in the direction of quantifying the non-linear shear, deformation and permeability behaviour of joints, based on the Barton-Bandis (BB) rock engineering modelling concepts. The term ‘modelling’ will be used to introduce the basic stress-displacement-dilation behaviour of joints in shear, and the basic stress-closure behaviour when joints are compressed by increased normal stress. These are the basic elements of the (non-linear) behaviour, which are used when modelling the two- or
three-dimensional behaviour of a jointed rock mass. They are the basic BB (Barton-Bandis) components of any UDEC-BB distinct element numerical model (used commercially and for research since 1985). The BB approach can also be used to determine improved MC (Mohr-Coulomb) strength components for a 3DECMC three-dimensional distinct element numerical model. In other words for acquiring input at the
appropriate levels of effective stress, prior to BB introduction into 3DEC, believed to be a project underway. Due to space limitations, constant stiffness BB behaviour of rock joints is given elsewhere.
... Yet, despite the diversity of strength criteria available in the literature, the longestablished Mohr-Coulomb criterion remains the most commonly used in engineering practice, mainly due to its simplicity as well as to the ease for determining its constitutive parameters from laboratory tests. As pointed by previous studies [Bar16], this is rather problematic since Mohr-Coulomb criterion undoubtedly fails to capture the non-linear dependency of strength on the confinement which is a fundamental characteristics of shale rocks. Non-linear descriptions of strength should be more systematically used in practice, especially when considering the amplitude of effective stress changes they can experience in the field (e.g., several tens of MPa during petroleum production). ...
... Singh's strength parameters of Tournemire shale rock obtained by fitting the experimental data of[Bon17] (seeFigure 3).As pointed out by[Bar16], non-linearity is unavoidable when one wants to describe the strength of rocks over a wide range of confining pressures. This is rather evident for Tournemire shale which shows a sharp decrease in the rate of strength increase when 3 reaches values close to its UCS, at least for = 0° and = 45°. ...
Based on a comprehensive series of triaxial compression tests, we discuss the dependency of Tournemire shale strength on the orientation of the loading relative to the bedding over a large range of confining pressures (from 2 to 80 MPa). First, we assess the relevance of two practical empirical failure criteria to describe Tournemire shale strength. Then, we simulate the triaxial tests performed on Tournemire shale using an anisotropic discrete element model to get further insights into the mechanisms controlling its strength. In addition to its ability to reproduce the experimental strength envelopes reasonably well, the model provides an accurate description of the observed failure mechanisms: across the bedding for loadings applied parallel or perpendicular to it, and subparallel to the bedding for loadings applied at 45° relative to it. The model confirms that the non-linearity of the strength envelope is direction dependent, as are the underlying failure mechanisms. The model also suggests that crack initiation is pressure and direction independent at low to intermediate confining pressures (up to Sigma_3 = UCS), and that the strength is directly influenced by the way shear is mobilized through the fabric of the material.
... Extensive laboratory experiments on rock joint behavior from the early 1960s to date have shown that the shear behavior of rock joints is nonlinear. This nonlinearity is significantly affected by the dilation-induced joint roughness, causing the nonlinear relationship between joint shear stress and normal stress n in the versus n axes (e.g., Bandis et al., 1981;Barton, 1982;Barton et al., 1985;Barton, 2016;Barton & Choubey, 1977;Barton, 1973;Hencher & Richards, 2015;Indraratna & Haque, 2000) Surprisingly, and as pointed out by Barton (2016), the joint roughness and wall strength parameters, known as the contributing parameters to the nonlinearity of the shear strength of rock joints, were initially ignored and rejected by leading researchers in reservoir geomechanics, following development of the parameters in rock mechanics in the 1970's. The widespread use of linear behavior assumptions could lead to errors in reservoir interpretation since joint roughnessinduced behaviors such as dilation, aperture increase, and permeability increase, and also nonlinear closure reversing the above, were effectively ignored. ...
... Extensive laboratory experiments on rock joint behavior from the early 1960s to date have shown that the shear behavior of rock joints is nonlinear. This nonlinearity is significantly affected by the dilation-induced joint roughness, causing the nonlinear relationship between joint shear stress and normal stress n in the versus n axes (e.g., Bandis et al., 1981;Barton, 1982;Barton et al., 1985;Barton, 2016;Barton & Choubey, 1977;Barton, 1973;Hencher & Richards, 2015;Indraratna & Haque, 2000) Surprisingly, and as pointed out by Barton (2016), the joint roughness and wall strength parameters, known as the contributing parameters to the nonlinearity of the shear strength of rock joints, were initially ignored and rejected by leading researchers in reservoir geomechanics, following development of the parameters in rock mechanics in the 1970's. The widespread use of linear behavior assumptions could lead to errors in reservoir interpretation since joint roughnessinduced behaviors such as dilation, aperture increase, and permeability increase, and also nonlinear closure reversing the above, were effectively ignored. ...
In 1941, Belgian-born physicist Maurice Anthony Biot (1905-1985) developed the first equations that govern the coupled interactions between fluid flow and deformation in elastic porous media. This hydro-mechanical (H-M) interaction has started to receive wide attention in the field of tunnel engineering. In urban areas, the induced H-M interaction due to surface loading over an existing shallow tunnel can have a severe impact on short- and long-term tunnel stabilities, the degree of which remains unclear. Likewise, advancing tunnel in deep saturated ground causes time-dependent consolidation that is invoked by the transient nature of the coupled interaction. Yet, deep tunnel advance is still commonly simulated in one excavation step and under a steady state condition, oversimplifying the excavation-induced H-M interaction as proposed by Biot.
Explicit coupling techniques have been widely used for H-M analysis of such tunnel problems. However, explicit techniques are conditionally stable, requiring small time steps to maintain numerical stability. To improve the efficiency of H-M analysis, an unconditionally stable explicit finite difference scheme such as the alternating direction explicit (ADE) scheme could be used to solve the flow problem. Yet, the standard ADE scheme is only moderately accurate and restricted to uniform grids and plane strain conditions.
This thesis presents the derivation of novel high-order ADE schemes for non-uniform grids to solve the flow problems in plane strain and axisymmetric conditions. For each condition, the resulting pore pressure solutions from the new ADE scheme were sequentially coupled with a geomechanical simulator in Fast Lagrangian Analysis of Continua (FLAC), resulting in a novel and efficient sequentially-explicit coupling technique called SEA-4 for the plane strain problem and SEA-4-AXI for the axisymmetric problem. This thesis will show that by using SEA-4 and SEA-4-AXI, the H-M simulations of tunneling in saturated ground can be performed efficiently without numerical instability and yet still retain high numerical accuracy. Verifications from well-known consolidations and tunnel problems have shown that SEA-4 and SEA-4-AXI reduced the computer runtime to 20-66% that of FLAC’s basic flow scheme. They also maintained maximum absolute errors of < 6% for the pore pressure and < 1.5% for the displacement solutions, demonstrating their future application for producing efficient H-M simulations.
The H-M analysis also showed that under surface loading, tunnel stability in addition to ground strength was largely influenced by liner permeability and the long-term H-M response of the ground. The step-wise excavation in deep advancing tunnel caused a non-monotonic behavior of pore pressure, temporarily confining the advanced core, leading to a new insight for the convergence-confinement method (CCM) in saturated ground. Recognizing this transient coupling effect, this thesis proposed: (1) theoretical relationships between the extrusion and convergence and preconvergence of the face and the advance core, (2) an extended CCM using proposed transient unloading factors and (3) new semi-analytical equations for predicting the transient longitudinal displacement profile (LDP) of a deep saturated tunnel taking into account the transient coupling effect induced by the consolidation process.
In addition to the H-M analysis of tunneling, the thesis made two additional contributions to further explicate the role of H-M interaction in rock engineering in other applications. First, it presented the role of the coupled two-phase flow and geomechanical interaction of CO2 sequestration into deep underground reservoirs. Second, the thesis presented a newly developed constitutive model for predicting the nonlinear shear behavior of rock joints using the linearized implementation of the Barton-Bandis joint model. When this model is coupled with either SEA-4 or SEA-4-AXI, it can be potentially used for H-M analysis of tunneling in fractured saturated rock.
... Cross-Atlantic research (on non-linear description for rock joints) does not seem to be popular in geomechanics, despite 65% of remaining petroleum in naturally fractured reservoirs (NFR) with guaranteed non-linear behavior. See Barton, 2015 andBarton, 2016 for further discussion. Figure 10 The importance of variable frictional angles on rock slope stability (and indeed on slope deformation characteristics) are nicely illustrated by these early distinct element (μDEC) models which was a method developed by Cundall, and culminated in UDEC (UDEC-MC and UDEC-BB) and 3DEC-MC. ...
