Geometric and fractal analysis of dynamic cracking patterns subjected to wetting-drying cycles

Wang, Ce; Zhang, Zhanyu; Yang, Liu; Fan, Saijun

doi:10.1016/j.still.2017.02.005

Cited by 81 publications

(31 citation statements)

References 39 publications

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“…Therefore, the VðtÞ of the soil samples increases with the increase in the number of wetting-drying cycles from 0 to 4. On the other hand, the weakening effect of the cohesion between the soil particles of the soil sample reached a maximum after four wetting-drying cycles (Wang et al 2017). Hence, the VðtÞ reached a maximum and then remains stable with the increase in the number of wetting-drying cycle increase from 4 to 7.…”

Section: Effects Of the Wetting-drying Cycles On The Soil Disintegrationmentioning

confidence: 94%

Experimental study on the disintegration of granite residual soil under the combined influence of wetting–drying cycles and acid rain

Liu

Song

Huang

2019

Geomatics, Natural Hazards and Risk

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Granite residual soil has obvious disintegration characteristics, resulting in serious water and soil losses in South China. There is a lack of studies on the disintegration of granite residual soil. Therefore, it is important to determine the disintegration characteristics of granite residual soil, especially under combined influence of wetting-drying cycles and acid rain. Granite residual soil from Jinqiao Village, Yudou County of South China, was used as experimental material. The disintegration velocity was evaluated to investigate the effects of wetting-drying cycles and acid rain on soil disintegration characteristics. Under the pH conditions of acid rain, disintegration velocity increases as the number of wetting-drying cycles increases (from 0 to 4), reaches a maximum after four wetting-drying cycles; then remains relatively constant as the wetting-drying cycle number increases from 4 to 7. Meanwhile, under conditions of a given wetting-drying cycle number, disintegration velocity increases with the decrease in pH from 7 to 4, reaches a maximum at a pH of 4, and then remains relatively constant when the pH decreases from 4 to 1. Moreover, the disintegration velocity under the combined influence of wetting-drying cycles and acid rain is considerably higher than that under individual factor.

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Section: Effects Of the Wetting-drying Cycles On The Soil Disintegrationmentioning

confidence: 94%

Experimental study on the disintegration of granite residual soil under the combined influence of wetting–drying cycles and acid rain

Liu

Song

Huang

2019

Geomatics, Natural Hazards and Risk

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“…The collected soil was subjected to an image processing analysis, and the pore widths that corresponded to different particle sizes were counted to determine a large-pore soil model. This paper uses the set of measurements to analyze particles by Image J software (1.8.0, National Institutes of Health, Bethesda, MD, USA, 2020), obtain and calculate the porosity and pore channel width of the soil layer in the same plane as the steam disinfection pipe (SDP) [24][25][26]. The morphological characteristics of pores treated with different particle sizes are shown in Table 1 and Figure 3.…”

Section: Selection Of Soil Macropore Modelmentioning

confidence: 99%

Influence of Soil Particle Size on the Temperature Field and Energy Consumption of Injected Steam Soil Disinfection

et al. 2020

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Soil steam disinfection (SSD) technology is an effective means of eliminating soil borne diseases. Among the soil cultivation conditions of facility agriculture in the Yangtze River Delta region of China, the clay soil particles (SPs) are fine, the soil pores are small, and the texture is relatively viscous. When injection disinfection technology is applied in the clay soil, the diffusion of steam is hindered and the heating efficiency is substantially affected. To increase the heating efficiency of SSD, we first discretized the continuum model of Philip and De Vries into circular particle porous media of different sizes and random distribution. Then with Computational Fluid Dynamics (CFD) numerical simulation technology, a single-injection steam disinfection model for different SP size conditions was constructed. Furthermore, the diffusion pattern of the macro-porous vapor flow and matrix flow and the corresponding temperature field were simulated and analyzed. Finally, a single-pipe injection steam disinfection verification test was performed for different SP sizes. The test results show that for the clay soil in the Yangtze River Delta region of China, the test temperature filed results are consistent with the simulation results when the heat flow reaches H = 20 cm in the vertical direction, the simulation and test result of the heat flow in the maximum horizontal diffusion distance are L = 13 cm and 12 cm, respectively. At the same disinfection time, the simulated soil temperature change trend is consistent with the test results, and the test temperature is lower than the simulated temperature. The difference between the theoretical temperature and the experimental temperature may be attributed to the heat loss in the experimental device. Further, it is necessary to optimize the CFD simulation process and add the disintegration and deformation processes of soil particle size with the change of water content. Furthermore, the soil pores increase as the SP size increases and that a large amount of steam vertically diffuses along the macropores and accumulates on the soil surface, causing ineffective heat loss. Moreover, soil temperature distribution changes from oval (horizontal short radius/vertical long radius = 0.65) to irregular shape. As the SP size decreases, the soil pore flow path becomes fine; the steam primarily diffuses uniformly around the soil in the form of a matrix flow; the diffusion distance in the horizontal direction gradually increases; and the temperature distribution gradually becomes even, which is consistent with the soil temperature field simulation results. Similar to the energy consumption analysis, the maximum energy consumption for SP sizes>27mm and <2mm was 486and 477kJ, respectively. Therefore, proper pore growth was conducive to the diffusion of steam, but excessive pores cause steam to overflow, which increased energy consumption of the system. Considering that the test was carried out in an ideal soil environment, the rotary tiller must be increased for fine rotary tillage in an actual disinfection operation. Although large particles may appear during the rotary tillage process, an appropriate number of large particles contributes to the formation of a large pore flow, under the common effect of matrix flow, it will simultaneously promote greater steam diffusion and heating efficiency. The above theoretical research has practical guiding significance for improving the design and disinfection effect of soil steam sterilizers in the future.

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“…1and Wong (1986), Nasseri et al (2007 and and Griffiths et al (2017) studied and calculated microcrack densities of heated granite. There are also studies which use numerical image analysis to calculate crack geometries (Arena et al, 2014;Delle Piane et al, 2015;Griffiths et al, 2017;Wang et al, 2017). Wang et al (2017) also perform a fractal analysis of cracking patterns.…”

Section: Calculation Of Surface Macro-cracks Densitymentioning

confidence: 99%

“…There are also studies which use numerical image analysis to calculate crack geometries (Arena et al, 2014;Delle Piane et al, 2015;Griffiths et al, 2017;Wang et al, 2017). Wang et al (2017) also perform a fractal analysis of cracking patterns. However, there were relatively few studies on surface macro-cracks of granite samples with internal defects after or under high temperature treatment.…”

Section: Calculation Of Surface Macro-cracks Densitymentioning

confidence: 99%

Effects of pre-existing fissures on surface macro-crack characteristics of granite subjected to elevated temperatures

Zhao¹

2019

Acta Geodynamica Et Geomaterialia

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In order to study thermal macro-cracks on granite surface, experiments were conducted to heat orthoclase granite samples under 25-800 °C. This paper reports a method for evaluating thermal damage of rock by indexes of thermal macro-cracks characteristics, including the width of macro-cracks, the length of macro-cracks, the density of macro-cracks and fractal analysis of macro-cracks. The major findings are as follows: (1) As treatment temperature increases from 500 °C to 800 °C, the average macro-crack width increases from 0.05 to 0.22 mm. And the average macro-crack length increases from 34.36 to 771.86 mm at 600-800 °C. In addition, the linear density is from 0.20 to 1.05 mm-1 and the surface density increases from 0.07 to 1.54 mm/mm 2 at 600-800 °C. (2) The temperature has an important influence on the thermal fracture fractal of the granite surface. As treatment temperature increases from 600 °C to 800 °C, the fractal dimension of macro-cracks changes from 0.47 to 1.43. (3) 400-500 °C is the threshold temperature of the thermal macro-cracks generated on the granite surface and the high temperature causes the unpenetrated fissures connect with each other.

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Geometric and fractal analysis of dynamic cracking patterns subjected to wetting-drying cycles

Cited by 81 publications

References 39 publications

Experimental study on the disintegration of granite residual soil under the combined influence of wetting–drying cycles and acid rain

Experimental study on the disintegration of granite residual soil under the combined influence of wetting–drying cycles and acid rain

Influence of Soil Particle Size on the Temperature Field and Energy Consumption of Injected Steam Soil Disinfection

Effects of pre-existing fissures on surface macro-crack characteristics of granite subjected to elevated temperatures

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