Scale effect on the shear behaviour of rock joints based on a numerical study

Bahaaddini, M.; Hebblewhite, Bruce; Mitra, R.

doi:10.1016/j.enggeo.2014.07.018

Cited by 164 publications

(57 citation statements)

References 24 publications

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“…In the first step, the geometric coordinates of the 10 standard roughness joint profiles are acquired using image processing technology. In the second step, these joints are set into a numerical model of rock sample generated by the bonded particle method (BPM) in Particle Flow Code (PFC 2D ) and simulated by the modified smooth joint model (MSJM) [30][31][32][33][34][35][36][37][38][39][40] Figure 3.…”

Section: Proposed New Methods For Estimating Jrc Of Joint Profilementioning

confidence: 99%

“…is function has been verified to better simulate the mechanical properties of rough joints [33][34][35].…”

Section: Simulation Of Joint With Smooth Joint Modelmentioning

confidence: 99%

“…After giving an initial stiffness, the particles generated previously were allowed to rearrange and reached the static equilibrium under zero friction condition. Before installing bond, particles with less than one contact were eliminated to produce a series of highly interlocked particles [33,34]. en, the bonded particle model (BPM) was installed at a contact point between all particles to simulate intact rock [30][31][32][33][34][35][36][37][38][39][40].…”

Section: Simulation Of Joint With Smooth Joint Modelmentioning

confidence: 99%

“…In the past ten years, numerical simulation is becoming more and more widely used in geotechnical engineering [29][30][31][32][33][34][35]. With the continuous innovation of computational mechanics, the discrete element method (DEM) in particulate and blocky systems has a rapid development [30][31][32][33][34][35][36][37][38][39].…”

Section: Introductionmentioning

confidence: 99%

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A New Method to Estimate the Joint Roughness Coefficient by Back Calculation of Shear Strength

Huan

Zhang

et al. 2019

Advances in Civil Engineering

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The joint roughness coefficient (JRC) is an important factor affecting the shear properties of rock joints, and its accurate estimation is a challenging task in rock engineering. Existing JRC evaluation approaches such as the empirical comparison method and the statistical parameter method have some unresolved defects. In this study, a new method is proposed for JRC estimation to overcome the deficiencies of existing approaches based on back calculation of shear strength. First, the 10 standard roughness joints are established in numerical rock samples generated by the bonded particle method (BPM). Secondly, the microscopic parameters of the intact rock and joints are calibrated, and a series of direct shear tests of joint samples are carried out under different normal stresses. Finally, the empirical relationships between shear strength and JRC are proposed under high correlation conditions. The results show that the modified smooth joint model (MSJM) is proved to better simulate the mechanical properties of rough joints than the smooth joint model (SJM). When the shear strength of target joint is substituted in the corresponding relationship, the JRC of joint along the shear direction can be conveniently obtained. In addition, the JRC values of 10 standard roughness joint profiles under shear direction of from right to left (FRTL) are obtained. By estimating the JRC of 9 target joints in the literature, it can be seen that the new method proposed in this paper can well reflect the directionality of roughness and it is convenient to apply.

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Section: Proposed New Methods For Estimating Jrc Of Joint Profilementioning

confidence: 99%

“…is function has been verified to better simulate the mechanical properties of rough joints [33][34][35].…”

Section: Simulation Of Joint With Smooth Joint Modelmentioning

confidence: 99%

Section: Simulation Of Joint With Smooth Joint Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A New Method to Estimate the Joint Roughness Coefficient by Back Calculation of Shear Strength

Huan

Zhang

et al. 2019

Advances in Civil Engineering

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“…In the last decades, scale effects on mechanical properties relevant to geotechnical problems have been the subject of many studies (Adey & Pusch, 1999;Bahaaddini, Hagan, Mitra, & Hebblewhite, 2014;Fardin, Stephansson, & Jing, 2001;Guo & Stolle, 2006;Yilmaz, Belem, & Benzaazoua, 2015;Yoshinaka, Osada, Park, Sasaki, & Sasaki, 2008;Zhu, Clark, & Phillips, 2001). However, experimental studies of scale effects on hydraulic conductivity and solute transport parameters have received less attention.…”

Section: Introductionmentioning

confidence: 99%

Upscaling of water flow and mass transport in a tropical soil: numerical, laboratory and field studies

Godoy¹

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Numerical models are becoming fundamental tools to predict a range of complex problems faced by geotechnical and geo-environmental engineers. However, to render the model reliable for future predictions, the model input parameters must be determined with consideration of the scale effects. If there is a difference of scales between the observation and the model scales there are two possible ways to consider it: or models are constructed with elements of a size similar to that at which the data were measured, or some upscaling rules must be defined. In this context, this thesis focuses on upscaling of water flow and mass transport in a tropical soil by means of numerical, laboratory and field studies. This thesis is organized in four parts.First, the heterogeneity, correlation and cross-correlation between solute transport parameters (dispersivity, α, and partition coefficient, Kd) and soil properties are studied in detail. In this part, it is verified that the hydraulic conductivity (K) and solute transport parameters are highly heterogeneous, while soil properties are not. Spatial correlation of α, K, and statistically significant variables are studied, and it would probably improve the estimation only in a small-scale study, since the spatial correlation are only observed up to 2.5 m. This study is a first attempt to evaluate the spatial variation in the correlation coefficient of transport parameters of a reactive and a nonreactive solute, indicating the more relevant variables and the one that should be included in future studies.In the second part, scale effect on K, dispersivity and partition coefficient of potassium and chloride are studied experimentally by means of laboratory and field experiments. The purpose is to contribute to the discussion about scale effects on K, α and Kd and understanding how these parameters behave with the change in the scale of measurement. Results show that K values increases with scale, regardless of the method of measurement, except for the results obtained from double-ring infiltrometer tests. Dispersivity trends to increase exponentially with the sample height.Partition coefficient tends to increase with sample length, diameter and volume. These differences in the parameters according to the scale of measurement must be considered when these observations are later used as input to numerical models, otherwise the responses can be misrepresented.x Third, stochastic analysis of three-dimensional hydraulic conductivity upscaling is performed using a simple average and the Laplacian-with-skin methods for a variety of block sizes based on real K measurements. In this part it is demonstrated the errors that can be introduced by using a deterministic upscaling using simple averages of the measured K without accounting for the spatial correlation. Results show that K heterogeneity can be incorporated in the daily practice of the geotechnical modeler.The aspects to consider when performing the upscaling are also discussed. Finally, the dependence of the exponent of the p-n...

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Experimental, analytical, and finite element assessment of the shear strength of concrete‐rock interfaces at different scales

Renaud

Bouaanani

Miquel

2021

Num Anal Meth Geomechanics

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This paper presents an original analytical approach to assess the shear strength of concrete‐rock interfaces while accounting for the effects of scale, roughness and matching conditions. The technique proposed is based on experimental data obtained from small core samples extracted from existing dam sites, with diameters varying from 83 to 145 mm, and larger rectangular samples with side lengths comprised between 320 and 492 mm. The predictions of the analytical formulation are validated against results of direct shear tests, as well as 3D nonlinear finite element simulations. Sensitivity analyses are conducted to evaluate the influence of roughness and matching conditions on the shear behavior of concrete‐rock contacts at different scales. The main results show that: (i) roughness inhomogeneity is one of the main causes of scale effects on the shear strength of concrete‐rock interfaces; (ii) contact geometries proportional in both length and height are expected to present quite similar shear strengths; and (iii) geometry matching conditions must be accounted for as they might be the source of scale effects affecting the evaluation of the shear strength at concrete‐rock interfaces. New equations are also proposed to suggest values of apparent cohesion and friction angle for concrete‐rock contacts.

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Scale effect on the shear behaviour of rock joints based on a numerical study

Cited by 164 publications

References 24 publications

A New Method to Estimate the Joint Roughness Coefficient by Back Calculation of Shear Strength

A New Method to Estimate the Joint Roughness Coefficient by Back Calculation of Shear Strength

Upscaling of water flow and mass transport in a tropical soil: numerical, laboratory and field studies

Experimental, analytical, and finite element assessment of the shear strength of concrete‐rock interfaces at different scales

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