scholarly journals Experimental Reproducibility and Natural Variability of Hydraulic Transport Properties of Fractured Sandstone Samples

Geosciences ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 458
Author(s):  
Sascha Frank ◽  
Thomas Heinze ◽  
Mona Ribbers ◽  
Stefan Wohnlich
Keyword(s):  
Fracture Surface ◽  
Surface Morphology ◽  
Transport Properties ◽  
Natural Variability ◽  
Transport Processes ◽  
Fracture Aperture ◽  
Hydraulic Transport ◽  
Fracture Surface Morphology ◽  
Transport Parameters ◽  
Hydraulic Aperture

Flow and transport processes in fractured systems are not yet fully understood, and it is challenging to determine the respective parameters experimentally. Studies on 10 samples of 2 different sandstones were used to evaluate the reproducibility of tracer tests and the calculation of hydraulic transport properties under identical boundary conditions. The transport parameters were determined using the advection–dispersion equation (ADE) and the continuous time random walk (CTRW) method. In addition, the fracture surface morphology and the effective fracture aperture width was quantified. The hydraulic parameters and their variations were studied for samples within one rock type and between both rock types to quantify the natural variability of transport parameters as well as their experimental reproducibility. Transport processes dominated by the influence of fracture surface morphology experienced a larger spread in the determined transport parameters between repeated measurements. Grain size, effective hydraulic aperture and dispersivity were identified as the most important parameters to evaluate this effect, as with increasing fracture aperture the effect of surface roughness vanishes and the experimental reproducibility increases. Increasing roughness is often associated with the larger effective hydraulic aperture canceling out the expected increased influence of the fracture surface morphology.

Investigating surface morphology and transport parameters of single fractures

2020 ◽  
Author(s):  
Sascha Frank ◽  
Thomas Heinze ◽  
Mona Ribbers ◽  
Stefan Wohnlich
Keyword(s):  
Fracture Surface ◽  
Surface Morphology ◽  
Transport Processes ◽  
Coarse Grained ◽  
Hydraulic Permeability ◽  
Transport Parameters ◽  
Flow And Transport ◽  
Fracture Surfaces ◽  
Depth Analysis ◽  
Surface Images

<p>In order to obtain a deeper understanding of flow and transport processes in fractures, experimental investigations and numerical modelling have been carried out focusing on the effects of fracture surface morphology. To determine a possible relationship between the roughness of fracture surfaces and hydraulic and transport parameters, two different types of sandstones has been investigated. The sandstones were a coarse-grained, inhomogeneous and strongly anisotropic Flechtinger sandstone (Bebertal, Germany) and a fine-grained, rather homogeneous, isotropic Remlinger sandstone (Würzburg, Germany).</p><p>The sandstones were first cored with a diameter of 100 mm and a height of 150 mm and split into individual fissures. The resulting fracture surfaces were scanned using a 3D scan and surface images were generated. These surface images were used to determine the Joint Roughness Coefficient (JRC) and other measures of roughness. The roughness has been characterized along 1D profiles in each direction. Mean values and spread have been calculated for each surface. The fracture surfaces are self-affine so that little variation along both surfaces has been determined. Both sandstone halves were then joined together and the reassembled fractured rock core was examined experimentally. Darcy and tracer tests were carried out for the investigations and hydraulic (permeability, fracture opening width) and transport parameters (flow velocity, dispersivity, dispersion coefficient) were derived from the results and compared with each other and with the surface roughness. For the Darcy experiments, the cores were clamped in a specially designed Darcy cell and calculations were done based on equations for the cubic law. The transport parameters were determined using a salt tracer and by evaluating the breakthrough curves, recorded by measuring the electrical conductivity, with the moment analysis.</p><p>First results show a very clear separation between Remlinger and Flechtinger sandstone. Thus, the finer-grained Remlinger cores show lower JRC than the coarser-grained Flechtinger, as expected. Further, the Flechtinger cores have larger aperture opening widths than the Remlinger cores. First comparisons show a tendency to higher dispersivity with higher JRC, and thus with the Flechtinger than in the case of the Remlinger cores. Though, in-depth analysis reveals that the JRC alone might not be sufficient to characterize transport processes along fractures, as anisotropy, as well as roughness variability along the fracture surface can influence flow and transport. Numerical modeling of flow paths across the fracture surface are used to relate experimental results with the flow pattern across the rough surface.</p>

Effect of peanut and walnut shells powders on tensile properties and morphological test by using heat cured PMMA as a matrix for prosthetic Denture

2021 ◽  
Vol 39 (2A) ◽  
pp. 196-205
Author(s):  
Zainab M. Abdul Monem ◽  
Jawad K. Oleiwi ◽  
Qahtan A. Hamad
Keyword(s):  
Fracture Surface ◽  
Surface Morphology ◽  
Matrix Material ◽  
Weight Fraction ◽  
Fracture Surface Morphology ◽  
Ductile Materials ◽  
Walnut Shells ◽  
Peanut Shells ◽  
The Matrix ◽  
Material Powder

In the current Research , the heat cured   matrix material powder of PMMA was reinforced with peanut and walnut shells (natural powders) which are chemically treated with 5% (w/v) (NaOH) to improve the matrix bonding (PMMA) before being used as a reinforcing powder and adding to exactly similar averages particle sizes ≤ (53µm), with different weight fractions of (4, 8, and 12 wt.%). The ASTM D638 is used for composite specimens of the tensile test. The results indicated that the Elastic modulus values reached its maximum value at (8 wt.%.) when reinforced with peanut shells particles (1.053Gpa) , while ,the values of tensile strength, elongation percentage at break, decrease as the weight fraction of peanut and walnut shells powder increase and the lowest values is obtained by reinforcing with peanut shells particles to reach their minimum values at (12 wt.%.) where the lowest values of them are (29 MPa, 2.758% ) respectively. The fracture surface morphology of pure PMMA seemed to be homogenous morphology in (SEM) test, whereas the fracture surface morphology of PMMA composite reinforced by (peanut and walnut shells) powders and shows a roughness fracture surface morphology this refer to semi ductile to ductile materials.

Research on Fracture Surface Morphology and Tensile Properties of Cellulose-Based Green Food Packaging Membrane Materials

2013 ◽  
Vol 469 ◽  
pp. 148-151
Author(s):  
Zhi Jian Li ◽  
Qing Jun Meng
Keyword(s):  
Tensile Strength ◽  
Fracture Surface ◽  
Surface Morphology ◽  
Food Packaging ◽  
Fracture Surface Morphology ◽  
Strength Performance ◽  
Green Food ◽  
Phase Inversion Technique ◽  
Performance Research ◽  
Membrane Strength

The Green food-packaging membranes were prepared with N-methylmorpholine-N-oxide (NMMO) as the major solvent by using L-S phase inversion technique. Scanning electron microscopy (SEM) was adopted to characterize fracture surface morphology of membrane, and tensile machine was adopted to test the membrane strength performance. Research results show with the concentration of cellulose increases from 5% to 9%, structure of membrane becomes compact, aperture size becomes small and even, value of tensile strength increases 59.6%, and value of elongation increases 67.5%. With dissolving temperature increases from 100°C to 120°C, structure of membrane becomes loose, pore size becomes big and uneven, value of tensile strength decreases 19.2%, and value of elongation decreases 13.1%. The research can provide the theoretical reference for optimizing technology, adjusting the structure of membrane, and improving the performances of membrane.

FRACTURE SURFACE MORPHOLOGY OF Pd40Cu30Ni10P20 AMORPHOUS ALLOY

2013 ◽  
Vol 3 (0) ◽  
Author(s):  
Alena Juríková ◽  
Jozef Miškuf ◽  
Kornel Csach ◽  
Elena Tabachnikova ◽  
Vladimír Bengus
Keyword(s):  
Amorphous Alloy ◽  
Fracture Surface ◽  
Surface Morphology ◽  
Fracture Surface Morphology

Nanofractography Of Composition B Fracture Surfaces with AFM

2003 ◽  
Vol 800 ◽  
Author(s):  
Y. D. Lanzerotti ◽  
J. Sharma ◽  
R. W. Armstrong ◽  
R. L. McKenney ◽  
T. R. Krawietz
Keyword(s):  
Atomic Force Microscopy ◽  
Tensile Strength ◽  
Fracture Surface ◽  
Surface Morphology ◽  
Fracture Surface Morphology ◽  
Fine Scale ◽  
Force Microscopy ◽  
Atomic Force ◽  
High Acceleration ◽  
Columnar Grains

ABSTRACTThe characteristics of TNT (trinitrotoluene) crystals in the fracture surface of Composition B (a melt-cast mixture of TNT and RDX) have been studied using atomic force microscopy (AFM). The size of TNT crystals has been examined by analyzing the surface structure that is exhibited after mechanical failure of the Composition B. The failure occurs when the material is subjected to high acceleration in an ultracentrifuge and the shear or tensile strength is exceeded. AFM examination of the topography of the Composition B fracture surface reveals fracture across columnar grains of the TNT. The width of the columnar TNT grains ranges in size from ∼ 1 μm to ∼ 2 μm. Their height ranges in size from ∼ 50 nm to ∼ 300 nm. Flat TNT columns alternate with TNT columns containing river patterns that identify the direction of crack growth. Steps in the river patterns are a few nanometers in depth. The TNT constitutent fracture surface morphology is shown to occur on such fine scale, beginning from adjacent columnar crystals only 1–2 μm in width, and including river marking step heights of only a few nanometers, that AFM-type resolution is required.

Effects of Cooling Condition on Hot Tearing during Investment Casting

2011 ◽  
Vol 264-265 ◽  
pp. 355-360 ◽  
Author(s):  
Saeid Norouzi ◽  
Hassan Farhangi
Keyword(s):  
Grain Size ◽  
Fracture Surface ◽  
Surface Morphology ◽  
Thermal Gradient ◽  
Solidification Process ◽  
Surface Characteristics ◽  
Hot Tearing ◽  
Cooling Condition ◽  
Fracture Surface Morphology ◽  
Cooling Conditions

In the present study, the effect of cooling condition on hot tearing tendency and hot tearing fracture surface morphology were investigated. Results show that, the hot tear fracture surface characteristics are nearly similar under different cooling conditions. The hot tear surface exhibits two main features; the brittle region and the ductile region. The results also indicate that cooling condition has multifaceted effects on hot tearing phenomenon. Increasing cooling rate increases the thermal gradient, which raises the hot tearing tendency; concomitantly it decreases the grain size and dendrite arm spacing which increases the strength of the material. The occurrence of hot tearing phenomenon under different cooling conditions is discussed and evaluated based on the competition between these opposing factors during the solidification process.

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