scholarly journals Characterization of rock joint surface anisotropy considering the contribution ratios of undulations in different directions

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Man Huang ◽  
Chenjie Hong ◽  
Chengrong Ma ◽  
Zhanyou Luo ◽  
Shigui Du
Keyword(s):  
Rock Joint ◽  
Weight Ratio ◽  
Rock Joints ◽  
Joint Surface ◽  
Orthogonal Direction ◽  
Natural Rock ◽  
Joint Surfaces ◽  
The Common ◽  
Joint Morphology

Abstract Anisotropy in rock joint is strongly dependent on undulating surface morphology. Recent research of the morphology showed the parameter can express the different types of anisotropic characteristics of the joint surface separately. This report aims to analyze the common characteristic of the anisotropic distribution and exhibit the anisotropic variation trend. The joint morphology function consists of two morphology functions of regular plane in orthogonal directions, and the anisotropic variation determined by the contribution ratios of the two morphology. The roughness weight ratio in orthogonal direction of joint surface is used as an index to describe the anisotropic variation behavior, which proposes the anisotropic variation coefficient (AVC). On this basis, it is divided into 5 levels from strong anisotropic to isotropic. According to the assumption of anisotropic arc distribution, the anisotropic analytic function is derived and the agreement between the deduced curves and measured data therefore suggests the possibility of defining the morphology anisotropy through the index AVC. Finally, we verify the characteristic of three natural rock joints, and prove the proposed function can reflect the anisotropic distribution trend. The new index can be used to describe the anisotropic variation behaviour of rock joint surfaces.

scholarly journals Scale Dependence of Waviness and Unevenness of Natural Rock Joints through Fractal Analysis

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Yingchun Li ◽  
Shengyue Sun ◽  
Hongwei Yang
Keyword(s):  
Surface Roughness ◽  
Rock Joint ◽  
Fractal Dimensions ◽  
Window Size ◽  
Scale Dependence ◽  
Rock Joints ◽  
Joint Surface ◽  
Triangular Prism ◽  
Natural Rock ◽  
Waviness And Unevenness

The scale dependence of surface roughness is critical in characterising the hydromechanical properties of field-scale rock joints but is still not well understood, particularly when different orders of roughness are considered. We experimentally reveal the scale dependence of two-order roughness, i.e., waviness and unevenness through fractal parameters using the triangular prism surface area method (TPM). The surfaces of three natural joints of granite with the same dimension of 1000 mm×1000 mm are digitised using a 3D laser scanner at three different measurement resolutions. Waviness and unevenness are quantitatively separated by considering the area variation of joint surface as grid size changes. The corresponding fractal dimensions of waviness and unevenness in sampling window sizes ranging from 100 mm×100 mm to 1000 mm×1000 mm at an interval of 100 mm×100 mm are determined. We find that both the fractal dimensions of waviness and unevenness vary as the window size increases. No obvious stationarity threshold has been found for the three rock joint samples, indicating the surface roughness of natural rock joints should be quantified at the scale of the rock mass in the field.

scholarly journals Neutrosophic Function with NNs for Analyzing and Expressing Anisotropy Characteristic and Scale Effect of Joint Surface Roughness

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Rui Yong ◽  
Leiyu Gu ◽  
Jun Ye ◽  
Shi-Gui Du ◽  
Man Huang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Scale Effect ◽  
Large Scale ◽  
Rock Joint ◽  
Rock Joints ◽  
Joint Surface ◽  
Roughness Coefficient ◽  
Statistical Assessment ◽  
Natural Rock

The shear behavior of rock mass significantly depends upon the surface roughness of rock joints which is generally characterized by the anisotropy characteristic and the scale effect. The large-scale natural rock joint surfaces, at Qingshi Town, southeast of Changshan County, Zhejiang Province, China, were used as a case study to analyze the roughness characteristics. A statistical assessment of joint roughness coefficient (JRC) indicated the roughness anisotropy of different sized rock joints. The lower limit (JRCmean-σ) was regarded as the determinate information, and the difference between lower and upper limits represented indeterminate information. The neutrosophic number (NN) was calculated to express the various JRC values. The parametric equations for JRC anisotropic ellipse were presented based on the JRC statistical assessment of joint profiles of various orientations. The JRC values of different sized joint samples were then quantitatively described by the neutrosophic function. Finally, a neutrosophic parameter ψ for evaluating the scale effect on the surface roughness anisotropy was introduced using the ratio of maximum directional roughness to minimum directional roughness. The case study indicates that the proposed method has the superiority in moving forward from subjective assessment to quantitative and objective analysis on anisotropy characteristic and scale effect of joint surface roughness.

Correlating acoustic emission sources with damaged zones during direct shear test of rock joints

2012 ◽  
Vol 49 (6) ◽  
pp. 710-718 ◽  
Author(s):  
Z.A. Moradian ◽  
G. Ballivy ◽  
P. Rivard
Keyword(s):  
Acoustic Emission ◽  
Acoustic Waves ◽  
Normal Load ◽  
Rock Joint ◽  
Load Condition ◽  
Rock Joints ◽  
Joint Surfaces ◽  
Rock Cores ◽  
Asperity Degradation ◽  
Constant Normal Load Condition

Applicability of acoustic emission (AE) for localizing asperity damaged zones and damage intensity in joint surfaces was evaluated in this paper. With this attempt, rock joint samples obtained from tension splitting of the rock cores were tested under constant normal load condition. The locations of the AE sources were determined from propagation velocity of acoustic waves and by measuring the transferring time from event source to AE sensor. These sources correspond to asperity damaged zones. The AE signals generated from asperity degradation of joint surfaces were detected during shear testing. The energy of the generated signals was also measured to assess the intensity of the asperity failure. The results of this study showed that the AE method has a good capability in localizing the asperities’ failure points and the intensity (energy) of the asperities’ failure.

Shear Failure Mechanism of Infilling Rock Joints and its PFC Simulation

2015 ◽  
Vol 723 ◽  
pp. 317-321 ◽  
Author(s):  
Lei Xu ◽  
Qing Wen Ren
Keyword(s):  
Failure Mechanism ◽  
Shear Test ◽  
Shear Failure ◽  
Failure Process ◽  
Rock Joint ◽  
Rock Joints ◽  
Particle Flow Code ◽  
Rock Masses ◽  
Natural Rock ◽  
Simulation Results

Infilling rock joints widely exist in natural rock masses, and the shear failure of infilling rock joints plays an important role in the instability of rock masses. In order to study the shear failure mechanism of infilling rock joints, Particle Flow Code is used to simulate the direct shear test of infilling rock joints. The PFC models with different infilling thickness are established firstly, and then the procedures of PFC simulation are described. In the end, the shear failure process of infilling rock joints with different infilling thickness is simulated. Based on the PFC simulation results, it can be concluded that the shear failure mode changes with increasing infilling thickness, and the shearing of the infilling rock joint rarely gives birth to microcracks in rock due to the existence of the infilling material.

scholarly journals Neutrosophic Functions of the Joint Roughness Coefficient and the Shear Strength: A Case Study from the Pyroclastic Rock Mass in Shaoxing City, China

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Jun Ye ◽  
Rui Yong ◽  
Qi-Feng Liang ◽  
Man Huang ◽  
Shi-Gui Du
Keyword(s):  
Shear Strength ◽  
Rock Mass ◽  
Rock Joint ◽  
Sampling Bias ◽  
Rock Joints ◽  
Joint Surface ◽  
Pyroclastic Rock ◽  
Roughness Coefficient ◽  
Joint Roughness Coefficient ◽  
Joint Roughness

Many studies have been carried out to investigate the scale effect on the shear behavior of rock joints. However, existing methods are difficult to determinate the joint roughness coefficient (JRC) and the shear strength of rock joints with incomplete and indeterminate information; the nature of scale dependency of rock joints is still unknown and remains an ongoing debate. Thus, this paper establishes two neutrosophic functions of the JRC values and the shear strength based on neutrosophic theory to express and handle the incomplete and indeterminate problems in the analyses of the JRC and the shear strength. An example, including four rock joint samples derived from the pyroclastic rock mass in Shaoxing city, China, is provided to show the effectiveness and rationality of the developed method. The experimental results demonstrate that the proposed neutrosophic functions can express and deal with the incomplete and indeterminate problems of the test data caused by geometry complexity of the rock joint surface and sampling bias. They provide a new approach for estimating the JRC values of the different-sized test profiles and the peak shear strength of rock joints.

Research on Three-Dimensional Roughness Characteristics of Tensile Granite Joint

2012 ◽  
Vol 204-208 ◽  
pp. 514-519 ◽  
Author(s):  
Fu Ting Sun ◽  
Qing Ren Jiang ◽  
Cheng Xue She
Keyword(s):  
Mechanical Properties ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Rock Joints ◽  
Joint Surface ◽  
Two Dimensional ◽  
Roughness Parameters ◽  
Topographic Data ◽  
Joint Surfaces

The three-dimensional roughness characteristics of the tensile granite joint surfaces are studied. Firstly, the tensile granite joints are prepared by splitting cubic granite blocks, and the triangular networks of the joint surfaces are established based on the topographic data collected by laser scanner. Then, the roughness characteristics of the two-dimensional profiles in different positions and different directions are studied. It proves that the roughness of the tensile granite joint surface is position and direction depended, and the roughness parameters based on the profiles are inadequate to characterize the roughness of the three-dimensional joint surfaces. Some new roughness parameters to characterize the three-dimensional joint surfaces are finally calculated on the basis of the triangular networks, these parameters can reflect the spatial and anisotropic characteristics of the joint surfaces. The results in this paper will lay the foundation for further study of the roughness characteristics and mechanical properties of the tensile rock joints.

scholarly journals Prediction of Peak Shear Strength of Natural, Unfilled Rock Joints Accounting for Matedness Based on Measured Aperture

2021 ◽  
Author(s):  
Francisco Ríos-Bayona ◽  
Fredrik Johansson ◽  
Diego Mas-Ivars
Keyword(s):  
Surface Roughness ◽  
Shear Strength ◽  
Rock Joint ◽  
Strength Criterion ◽  
Rock Joints ◽  
Coarse Grained ◽  
Peak Shear Strength ◽  
Shear Strength Criterion ◽  
Natural Rock ◽  
Contact Surfaces

AbstractThe mechanical behaviour of natural, unfilled rock joints is influenced by the interaction between surface roughness and matedness of the contact surfaces. In the field, natural rock joints normally exhibit a mismatch between the contact surfaces, mainly due to different geological processes such as weathering or deformations. Various attempts have been made to estimate how matedness of rock joints influences their peak shear strength. However, the proposed methodologies imply certain difficulties since they are intended to estimate the matedness of rock joints based mainly on visual inspection, and by relating an initial shear displacement to the length of the analysed sample or by relating the opening of saw-tooth and two-dimensional joint profiles with the degree of interlocking. Therefore, a tested peak shear strength criterion for natural, unfilled rock joints that realistically accounts for the influence of matedness on their peak shear strength is still lacking. This paper presents a methodology where objective measurements of the average aperture of natural, unfilled rock joints are used to estimate their matedness as a step in the prediction of the peak shear strength. This measured average aperture is based on high-resolution optical scanning of the surface roughness. The proposed relationship between measured average aperture and matedness of natural rock joints has been included in a further developed peak shear strength criterion. The verification against ten natural rock joint samples of coarse-grained granite showed that the revised criterion can predict the peak shear strength considering rock joint matedness.

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