scholarly journals Strength Model of Backfill-Rock Irregular Interface Based on Fractal Theory

2021 ◽  
Vol 8 ◽  
Author(s):  
Yue Zhang ◽  
Zhihong Zhang ◽  
Lijie Guo ◽  
Xiuli Du
Keyword(s):  
Shear Strength ◽  
Fractal Dimension ◽  
Mechanistic Model ◽  
Fractal Theory ◽  
Quantitative Relationship ◽  
Strength Model ◽  
Interface Shear ◽  
Engineering Significance ◽  
Direct Shear Testing ◽  
Irregular Interface

In the two-step open stope subsequent filling mining method, the determination of the strength model for the backfill-rock interface is of great engineering significance to study the stress distribution and stability of the backfill in the stope. Considering the deformation mechanism of the interface and the interaction of the asperities, a strength model for backfill-rock with irregular interface has been proposed based on fractal theory, which can effectively describe the shear mechanical behavior of interfaces with random roughness. The model has been compared with the two-body mechanistic model and good agreements have been achieved. The results show that the shear strength of the interface changes non-linearly with increasing fractal dimension D, when the fractal dimension D is in the range of 1∼1.12. The complete relationship between the interface shear strength and the fractal dimension is given, as the fractal dimension increases from 1 to 2 based on the presented model. At the same time, the quantitative relationship between the interface and backfill friction angles during direct shear testing is analyzed.

scholarly journals Response of Floc Networks in Cemented Paste Backfill to a Pumping Agent

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1906
Author(s):  
Jiaqi Zhu ◽  
Shunchuan Wu ◽  
Haiyong Cheng ◽  
Xiaojie Geng ◽  
Jin Liu
Keyword(s):  
Fractal Dimension ◽  
Fractal Theory ◽  
Mineral Resources ◽  
Cemented Paste Backfill ◽  
Sem Image ◽  
Multi Scale ◽  
Paste Backfill ◽  
Engineering Significance ◽  
Deep Underground ◽  
Dominant Structure

Cemented paste backfill is critical for the development of green mines, the safe exploitation of mineral resources deep underground, and the efficient disposal of solid wastes produced by mining. In this paper, the mechanism underpinning how the pumping agent works was studied. The number, area, and fractal dimension of pores in the microstructure of fresh paste were quantitatively analyzed using scanning electron microscopy (SEM), image processing, and fractal theory, and the response of flocs was investigated. The results show that floc networks disintegrated and the liquid network became the dominant structure under the action of the pumping agent, which enhanced the lubrication and promotion of multi-scale particles. In addition, the force chains became fragile and scattered, diminishing the yield stress of the paste. The pores had a more homogenized dimension and the porosity was 15.52% higher. The increase in the fractal dimension of the pores indicated that there was a higher self-similarity, in terms of microstructure, with a strengthened liquid network. The migration of floc structures contributed to the enhancement of the fluidity and rheology of the paste. This study provides insights into the effects of floc and liquid networks on the performance of paste, and it is of engineering significance in terms of realizing safe and efficient CPB operations.

Interface shear strength properties of geogrid-reinforced steel slags using a large-scale direct shear testing apparatus

2020 ◽  
Vol 48 (5) ◽  
pp. 625-633 ◽  
Author(s):  
Farshid Maghool ◽  
Arul Arulrajah ◽  
Mehdi Mirzababaei ◽  
Cherdsak Suksiripattanapong ◽  
Suksun Horpibulsuk
Keyword(s):  
Shear Strength ◽  
Large Scale ◽  
Strength Properties ◽  
Direct Shear ◽  
Shear Testing ◽  
Interface Shear Strength ◽  
Interface Shear ◽  
Testing Apparatus ◽  
Reinforced Steel ◽  
Direct Shear Testing

scholarly journals Fractal characteristics of reservoir structural fracture: a case study of Xujiahe Formation in central Yuanba area, Sichuan Basin

2018 ◽  
Vol 22 (2) ◽  
pp. 113-118 ◽  
Author(s):  
Cunhui Fan ◽  
Qirong Qin ◽  
Dongfeng Hu ◽  
Xiaolei Wang ◽  
MengYue Zhu ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Correlation Coefficient ◽  
Oil And Gas ◽  
Fractal Theory ◽  
Quantitative Relationship ◽  
Fold Belt ◽  
Xujiahe Formation ◽  
Capacity Dimension ◽  
Fracture Development ◽  
Fractal Characteristics

The reservoir structural fractures have excellent fractal characteristics, as well as self-similarities. Based on the fractal theory, the surface fractal characteristics of faults and the fractal characteristic of fractures in the core of the Xujiahe Formation in the Fault-Fold Belt of the central Yuanba area were studied, and a quantitative relationship was set up between them. Based on the fractal characteristics of faults, predictions were made of the favorable fracture zone, which provides a new idea for the research of fracture, as well as offers theoretical references for exploring the fracture development zone during oil-gas exploration. The results show the following: the seismic value of reflection fault fractal dimension of the Xujiahe Formation is 1.5284; the correlation coefficient R2 is bigger than 0.9901; the capacity dimension linear regression correlation coefficient of the fracture in core of the Xujiahe Formation is bigger than 0.98; the fractal dimension D can well reflect the fault and fracture development degree, as well as the complexity of the fracture system; it can quantitatively calculate the density of the fracture of the reservoir in the area; the areas of capacity dimension bigger than 1.45 are the fracture development zones in the Fault-Fold Belt of the central Yuanba area; the oil and gas enrichment degree is high; the areas with the fractal dimension value between 0.95 and 1.45 are the fracture relatively-developed zones; the fractal dimension with values smaller than 0.95 are the lack of fracture areas. 

scholarly journals Dynamic characteristics and fractal representations of crack propagation of rock with different fissures under multiple impact loadings

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bing Sun ◽  
Shun Liu ◽  
Sheng Zeng ◽  
Shanyong Wang ◽  
Shaoping Wang
Keyword(s):  
Fractal Dimension ◽  
Crack Propagation ◽  
Crack Growth ◽  
Impact Test ◽  
Fractal Theory ◽  
Dynamic Change ◽  
Fractal Dimensions ◽  
Peak Stress ◽  
Dynamic Mechanical Properties ◽  
Gravitational Potential Energy

AbstractTo investigate the influence of the fissure morphology on the dynamic mechanical properties of the rock and the crack propagation, a drop hammer impact test device was used to conduct impact failure tests on sandstones with different fissure numbers and fissure dips, simultaneously recorded the crack growth after each impact. The box fractal dimension is used to quantitatively analyze the dynamic change in the sandstone cracks and a fractal model of crack growth over time is established based on fractal theory. The results demonstrate that under impact test conditions of the same mass and different heights, the energy absorbed by sandstone accounts for about 26.7% of the gravitational potential energy. But at the same height and different mass, the energy absorbed by the sandstone accounts for about 68.6% of the total energy. As the fissure dip increases and the number of fissures increases, the dynamic peak stress and dynamic elastic modulus of the fractured sandstone gradually decrease. The fractal dimensions of crack evolution tend to increase with time as a whole and assume as a parabolic. Except for one fissure, 60° and 90° specimens, with the extension of time, the increase rate of fractal dimension is decreasing correspondingly.

scholarly journals Effect of Hydrophobic Silica Nanochannel Structure on the Running Speed of a Colloidal Damper

2021 ◽  
Vol 11 (15) ◽  
pp. 6808
Author(s):  
Gengbiao Chen ◽  
Zhiwen Liu
Keyword(s):  
Fractal Dimension ◽  
Silica Gel ◽  
Fractal Theory ◽  
Percolation Model ◽  
Silica Gels ◽  
Practical Significance ◽  
Running Speed ◽  
Fractal Percolation ◽  
Micropore Structure ◽  
Hydrophobic Silica

A colloidal damper (CD) can dissipate a significant amount of vibrations and impact energy owing to the interface power that is generated when it is used. It is of great practical significance to study the influence of the nanochannel structure of hydrophobic silica gel in the CD damping medium on the running speed of the CD. The fractal theory was applied to observe the characteristics of the micropore structure of the hydrophobic silica gel by scanning electron microscopy (SEM), the primary particles were selected to carry out fractal analysis, and the two-dimensional fractal dimension of the pore area and the tortuous fractal dimension of the hydrophobic silica gel pore structure were calculated. The fractal percolation model of water in hydrophobic silica nanochannels based on the slip theory could thus be obtained. This model revealed the relationship between the micropore structure parameters of the silica gel and the running speed of the CD. The CD running speed increases with the addition of grafted molecules and the reduction in pore size of the silica gel particles. Continuous loading velocity testing of the CD loaded with hydrophobic silica gels with different pore structures was conducted. By comparing the experimental results with the calculation results of the fractal percolation model, it was determined that the fractal percolation model can better characterize the change trend of the CD running velocity for the first loading, but the fractal dimension was changed from the second loading, caused by the small amount of water retained in the nanochannel, leading to the failure of fractal characterization.

scholarly journals Scale Characteristics and Optimization of Park Green Space in Megacities Based on the Fractal Measurement Model: A Case Study of Beijing, Shanghai, Guangzhou, and Shenzhen

2021 ◽  
Vol 13 (15) ◽  
pp. 8554
Author(s):  
Zhen Li ◽  
Wanmin Zhao ◽  
Miaoyao Nie
Keyword(s):  
Fractal Dimension ◽  
Evaluation System ◽  
Goodness Of Fit ◽  
Green Space ◽  
Fractal Theory ◽  
Measurement Model ◽  
Scale Structure ◽  
Qualitative Description ◽  
Urban Spatial Structure ◽  
Factors Affecting

This paper applies fractal theory to research of green space in megacity parks due to the lack of a sufficient qualitative description of the scale structure of park green space, a quantifiable evaluation system, and operable planning methods in traditional studies. Taking Beijing, Shanghai, Guangzhou, and Shenzhen as examples, GIS spatial analysis technology and the Zipf model are used to calculate the fractal dimension (q), the goodness of fit (R2), and the degree of difference (C) to deeply interpret the connotation of indicators and conduct a comparative analysis between cities to reveal fractal characteristics and laws. The research results show that (1) the fractal dimension is related to the complexity of the park green space system; (2) the fractal dimension characterizes the hierarchical iteration of the park green space to a certain extent and reflects the internal order of the scale distribution; (3) the scale distribution of green space in megacity parks deviates from the ideal pyramid configuration; and (4) there are various factors affecting the scale structure of park green space, such as natural base conditions, urban spatial structure, and the continuation of historical genes working together. On this basis, a series of targeted optimization strategies are proposed.

Influence of revision arthroplasty on bone/cement interface shear strength

1987 ◽  
Vol 20 (8) ◽  
pp. 824
Author(s):  
J.E. Bechtold ◽  
Y. Dohmae ◽  
R.E. Sherman ◽  
R.B. Gustilo
Keyword(s):  
Shear Strength ◽  
Bone Cement ◽  
Revision Arthroplasty ◽  
Interface Shear Strength ◽  
Interface Shear ◽  
Cement Interface
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