scholarly journals A Novel Discontinuity Roughness Parameter and Its Correlation with Joint Roughness Coefficients

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7631
Author(s):  
Huizhen Zhang ◽  
Changsuo Zhang ◽  
Zejin Yang ◽  
Zhiqiang Li ◽  
Chenlong Wang
Keyword(s):  
Size Effect ◽  
Spacing Effect ◽  
Anisotropy Parameter ◽  
Roughness Parameter ◽  
Morphological Characteristics ◽  
Shear Direction ◽  
Joint Roughness ◽  
Rock Discontinuities ◽  
Steep Slopes ◽  
Jrc Value

Joint roughness determination is a fundamental issue in many areas of rock engineering, because joint roughness has significant influences on mechanical properties and deformation behavior of rock masses. Available models suggested in the literature neglected combined effects of shear direction, scale of rock discontinuities, inclination angle, and amplitude of asperities during the roughness calculations. The main goals of this paper are to establish a comprehensive parameter that considers the characteristics of the size effect, anisotropy, and point spacing effect of the discontinuity roughness, and to investigate the correlation between the proposed comprehensive parameter and joint roughness coefficients. In this work, the Barton ten standard profiles are digitally represented, then the morphological characteristics of the discontinuity profiles are extracted. A comprehensive parameter that considers the characteristics of the size effect, anisotropy, and point spacing effect of the discontinuity roughness is established, and its correlation with joint roughness coefficients (JRC) is investigated. The correlation between the proposed discontinuity roughness parameter and the joint roughness coefficients can predict the JRC value of the natural discontinuities with high accuracy, which provides tools for comprehensively characterizing the roughness characteristics of rock discontinuities. The roughness index Rvh[−30°,0] reflects the gentle slope characteristics of the rock discontinuity profiles in the shear direction, which ignores the segments with steep slopes greater than 30° on the discontinuity profiles. The influence of steep slope segments greater than 30° should be considered for the roughness anisotropy parameter in the future.

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

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Jiu-yang Huan ◽  
Ming-ming He ◽  
Zhi-qiang Zhang ◽  
Ning Li
Keyword(s):  
Shear Strength ◽  
Joint Model ◽  
Rock Joints ◽  
New Method ◽  
Roughness Coefficient ◽  
Shear Direction ◽  
Joint Roughness Coefficient ◽  
Joint Roughness ◽  
Back Calculation ◽  
Smooth Joint Model

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.

scholarly journals Site effects on root characteristics and soil protection capability of two cover crops grown in South Bulgaria

2013 ◽  
Vol 61 (1) ◽  
pp. 30-38 ◽  
Author(s):  
Margarita L. Himmelbauer ◽  
Violeta Vateva ◽  
Ljudmila Lozanova ◽  
Willibald Loiskandl ◽  
Svetla Rousseva
Keyword(s):  
Cover Crops ◽  
Mass Density ◽  
Morphological Characteristics ◽  
Canopy Cover ◽  
Biomass Accumulation ◽  
Degradation Process ◽  
Soil Protection ◽  
Physical Parameters ◽  
Root Characteristics ◽  
Steep Slopes

Abstract Water erosion has been recognized as a major soil degradation process worldwide. This is of special relevance in the semi-arid areas of South Bulgaria with long periods of drought along with severe rainfall events. The main objective of this study was to evaluate the applicability of Bromus innermis L. and Lotus corniculatus L. for soil protection purposes under different site conditions. The site parameters considered were slope, fertilization and a range of soil physical parameters. The plant parameters were canopy cover, biomass, and root morphological characteristics. The experiment includes plots without and with eleven rates of NPK fertilization on gentle (6o) and steep slopes (12o). It was observed that the effect of fertilization on shoot and root growth was stronger on the gentle than on the steep slopes. The biomass accumulation was more sensitive to N than the PK fertilizer applications. The increase of the root density with increasing fertilization rates was more pronounced for the mass than for length or surface area. A significant effect on root diameter was found only for the variants with the highest N application. Treatments with the highest root mass density on both slopes showed the greatest potential for reducing erosion.

scholarly journals Neutrosophic Function for Assessing the Scale Effect of the Rock Joint Surface Roughness

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Rui Yong ◽  
Shaonan Tan ◽  
Jun Ye ◽  
Shigui Du
Keyword(s):  
Surface Roughness ◽  
Scale Effect ◽  
Rock Joint ◽  
Small Samples ◽  
Joint Surface ◽  
Roughness Coefficient ◽  
Joint Roughness ◽  
Large Joint ◽  
Negative Effect ◽  
Jrc Value

A new investigation method is proposed for recording large-sized joint profiles and making statistical analyses of the joint roughness coefficient (JRC) values of the 10–300 cm sized profiles. The mechanical hand profilograph is used for joint roughness measurement due to its advantage of easy operation and high accuracy in recording joint traces. Based on the proposed method, it provides sufficient samples from various positions on the large joint profile, which allows the statistical evaluation of JRC values. A neutrosophic number (NN) is employed for revealing determinate and/or indeterminate information as it consists of determinate and indeterminate parts. Due to the uncertainty of JRC in the real world, NN is chosen to represent the JRC value, which is not only random but also a fuzzy indefinite parameter. The neutrosophic function is used to analyze and express the scale effect of joint surface roughness, and its derivative is used to describe the changing trend of the scale effect. The results show that the JRC value of the joint profile is related to the scale and has a negative effect on the surface roughness of the rock joint. The indeterminate information about the scale effect on joint roughness is described by the neutrosophic functions, and the derivative indicated that the JRC values of small samples are more sensitive than those of large-sized examples. When the length of the sample exceeds the stationarity limit of 80 cm, the roughness appears to be almost scale independent.

scholarly journals Study on the Accurate Measurement and Quantitative Evaluation Methods of Aggregate Surface Roughness

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Luoke Li ◽  
Meng Guo ◽  
Cong Zeng
Keyword(s):  
Surface Roughness ◽  
Size Effect ◽  
Point Clouds ◽  
Roughness Coefficient ◽  
Parameter Method ◽  
Joint Roughness Coefficient ◽  
Joint Roughness ◽  
Quantitative Calculation ◽  
Contour Surface ◽  
Aggregate Particles

In this work, to quantitatively analyze the roughness of the surfaces of road aggregates, the contact measurement technique and contactless scanning technique were, respectively, used to capture the coordinate data of point clouds on the aggregate surface, which were then used to reconstruct the digital elevation models of aggregate particles. Then, the joint roughness coefficient (JRC) was used as an evaluation index, and the quantitative calculation methods of the two-dimensional (2D) contour line roughness and three-dimensional (3D) contour surface roughness of aggregate particles were, respectively, studied. Finally, the anisotropic characteristics and size effect of the roughness coefficients of aggregates with different lithologies were, respectively, investigated, based on which the practicability of the 3D roughness coefficient index was proven. The results demonstrate that the roughness of a road aggregate surface can be quantitatively described by the point cloud data. The 2D roughness of aggregate profile lines exhibits anisotropy, while the 3D roughness of the aggregate contour surface indicates the size effect. The subtle morphological changes of the surface textures of aggregates can be accurately described by the 3D joint roughness coefficient (JRC3D) calculated by the feature parameter method.

scholarly journals Research on the size effect of roughness on rock uniaxial compressive strength and characteristic strength

2021 ◽  
Vol 28 (1) ◽  
pp. 613-627
Author(s):  
Gaojian Hu ◽  
Yu Li ◽  
Gang Ma
Keyword(s):  
Compressive Strength ◽  
Size Effect ◽  
Uniaxial Compressive Strength ◽  
Strain Curve ◽  
Characteristic Size ◽  
Roughness Coefficient ◽  
Joint Roughness ◽  
Characteristic Strength ◽  
Relationship Of ◽  
The Relationship

Abstract The joint roughness has an influence on the uniaxial compressive strength (UCS) and characteristic strength of the rock, but the relationship of the influence is yet to be obtained. In this article, the influence of the size of the rock with rough joints on the UCS and the influence of the size effect of roughness on the UCS are studied by establishing 11 sets of numerical simulation schemes, a total of 30 working conditions. The stress–strain curve law of rocks with different roughness and sizes is analyzed, and the relationship between UCS and the size of rock with rough joints, joint roughness coefficient (JRC), is respectively proposed. Mathematical models of rock characteristic size of UCS, characteristic strength of the rock, and JRC are established, respectively.

scholarly journals A New Statistical Parameter for Determining Joint Roughness Coefficient (JRC) considering the Shear Direction and Contribution of Different Protrusions

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Jiu-yang Huan ◽  
Zhi-qiang Zhang ◽  
Ming-ming He ◽  
Ning Li
Keyword(s):  
Functional Relationship ◽  
Statistical Parameter ◽  
Sampling Interval ◽  
Processing Technology ◽  
Joint Surface ◽  
Roughness Coefficient ◽  
Shear Direction ◽  
Joint Roughness Coefficient ◽  
Joint Roughness ◽  
Coordinate Data

The mechanical properties of joints are important factors affecting the safety and stability of rock mass. The joint roughness coefficient (JRC) is a parameter for describing the roughness morphology of the joint surface, and its accurate quantification is very important to predict the shear strength. In the current statistical parameter methods for the estimation of joint roughness, the size of different protrusions on the joint surface was completely ignored, which did not correspond to the real failure mechanism of rock joint during the shear process. In this study, a new statistical parameter WPA was proposed for the estimation of JRC considering the shear direction and the contributions of different protrusions. First, the 10 standard roughness joint profiles were digitized based on image processing technology, and the obtained coordinate data were proved to be reliable by the calculation results of existing parameters. Secondly, the WPA value of 10 standard roughness joint profiles was calculated at a 0.5 mm sampling interval in two directions. The functional relationship between WPA and JRC indicated that they should be established in the same shear direction to maintain a high correlation. The JRC values of 10 standard roughness joint profiles in direction 2 were obtained based on the functional relationship established between WPA and JRC in direction 1, and the roughness of these 10 joint profiles was confirmed to be influenced by direction. Next, the effect of sampling interval on WPA was investigated. As the sampling interval increases, the WPA values gradually decreased and the correlation between them and JRC gradually declined. In practical application, a smaller sampling interval was recommended for more accurate prediction. Finally, the geometric coordinate data of 21 joint profiles given in the literature and 4 natural joint surfaces were obtained by graphics processing technology and 3D scanning technology, respectively. The JRC values of them were separately estimated by WPA in different directions. The results showed that the new statistical parameter WPA proposed in this paper can well describe the joint roughness considering the shear direction and the contribution of different protrusions.

Cell Wall Ultrastructure in Three Strains of a Cariogenic Streptococcus

1971 ◽  
Vol 29 ◽  
pp. 338-339
Author(s):  
M. J. Kramer ◽  
Alan L. Coykendall
Keyword(s):  
Cell Wall ◽  
Dental Caries ◽  
Streptococcus Mutans ◽  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Genetic Heterogeneity ◽  
Morphological Characteristics ◽  
Electron Microscopic ◽  
Dna Reassociation ◽  
Wall Ultrastructure

During the almost 50 years since Streptococcus mutans was first suggested as a factor in the etiology of dental caries, a multitude of studies have confirmed the cariogenic potential of this organism. Streptococci have been isolated from human and animal caries on numerous occasions and, with few exceptions, they are not typable by the Lancefield technique but are relatively homogeneous in their biochemical reactions. An analysis of the guanine-cytosine (G-C) composition of the DNA from strains K-1-R, NCTC 10449, and FA-1 by one of us (ALC) revealed significant differences and DNA-DNA reassociation experiments indicated that genetic heterogeneity existed among the three strains. The present electron microscopic study had as its objective the elucidation of any distinguishing morphological characteristics which might further characterize the respective strains.

Aberrant Type C Virus Production in a Cell Line Derived from Balb/3T3

1972 ◽  
Vol 30 ◽  
pp. 286-287
Author(s):  
N. Savage ◽  
A. Hackett
Keyword(s):  
Electron Microscopy ◽  
Cell Line ◽  
Leukemia Virus ◽  
Morphological Characteristics ◽  
Virus Production ◽  
Oncogenic Viruses ◽  
Endogenous Virus ◽  
Virus Particles ◽  
Moloney Leukemia Virus ◽  
A Cell

A cell line, UC1-B, which was derived from Balb/3T3 cells, maintains the same morphological characteristics of the non-transformed parental culture, and shows no evidence of spontaneous virus production. Survey by electron microscopy shows that the cell line consists of spindle-shaped cells with no unusual features and no endogenous virus particles.UC1-B cells respond to Moloney leukemia virus (MLV) infection by a change in morphology and growth pattern which is typical of cells transformed by sarcoma virus. Electron microscopy shows that the cells are now variable in shape (rounded, rhomboid, and spindle), and each cell type has some microvilli. Virtually all (90%) of the cells show virus particles developing at the cell surface and within the cytoplasm. Maturing viruses, typical of the oncogenic viruses, are found along with atypical tubular forms in the same cell.

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