Rough fractures

Figure 2b. Photon detector current as a function of time and corresponding fracture surface micrograph for rough fracture surfaces of TGDDM/DDS.

Makurat, A. 1985. The effect of shear displacement on the permeability of natural rough fractures. In Hydrogeology of Rocks of Low Permeability, Proc. 17th Int. Congr. Hydrogeol., Tucson, AZ, pp. 99-106. 

The recovered starch is mixed with water and weak soda lye and run into a row of wooden boxes, the bottoms of which are perforated and covered with cloth. These boxes arc lifted and dropped again to assist the draining. After 24 hours the blocks of compact starch which have formed, and still contain 42 to 44 per cent, of water, are cut into rectangular blocks ready for drying. It is now more usual to employ filter moulds where pressure is used, but it is necessary in this case not to use a milk of more than i 2 to 1 25 specific gravity, otherwise the finished product has an undesirable rough fracture. 

Figure 1.19 Micrographs of microemulsion droplets of the o/w-type in the system II2O- n-octane-CnEs prepared near the emulsification failure boundary at ya = 0.022, wb = 0.040 and T = 26.1 °C. (a) Freeze-fracture direct imaging (FFDI) picture showing dark spherical oil droplets of a mean diameter = 24 9 nm in front of a grey aqueous background. Note that each oil droplet contains a bright domain of elliptic shape which is interpreted as voids, (b) The freeze-fracture electron microscopy (FFEM) picture supports the FFDI result. Each fracture across droplets which contain bubbles shows a rough fractured surface. (From Ref. [26], reprinted with permission of Elsevier.)...

Other Potential Applications—Unsaturated Flow on Rough Fracture Surfaces... 

The approach for unsaturated conductivity outlined in previous sections was extended to modeling the unsaturated hydraulic conductivity of rough fracture surfaces (Or Tuller, 2000). Flow on rough fracture surfaces is an essential component required for deriving constitutive relationships for flow in unsaturated fractured porous media (Or Tuller, 2001). The detailed derivations are obtained by consideration of a dual porosity model (matrix - fracture) and the proportional contributions to flow from these different pore spaces. 

Thompson, M.E. 1991b. Numerical simulation of solute transport in rough fractures. J. Geophys. Res. 96 4157—4166. 

Tokunaga TK, Wan J, Sutton SR (2000) Transient film flow on rough fracture surfaces. Water Resources Research 36 1737-1746... 

Lee, H.S. and T.F. Chou, (2002), Hydraulic Characteristics of Rough Fractures in Linear Flow under Normal and Shear Load, Rock Mech.Rock Engng, 35(4), 299-318. 

SIMULATION OF COUPLED FLUID FLOW AND SOLUTE TRANSPORT IN A ROUGH FRACTURE... 

It is difficult to describe the complex forms and status of natural fracture surfaces with ordinary functions. The fractal theory can be used to describe extremely irregular geometric patterns, and many researches have indicated that it is reasonable to simulate rough fracture surfaces with fractals theory. At present, the self-affine fractal model is regarded as the best fractal model to simulate fracture surface. In the following, random Brown function method (Weierstrass- Mandelbrot function) is used to simulate a fractal fracture surface. 

It can be seen from water flow simulation result (Fig. 3 and Fig. 5) that, there is obvious evidence of channeling flow in the seepage through rough fractures. This is accordant to the... 

Brown, S.R., 1995. Simple Mathematical Model of rough Fracture, Journal of Geophysical Research 100 pp. 5941-5952 Hsu, C.T. Cheng, P. 1990. Thermal dispersion in porous medium. International Journal of Heat and Mass Transfer 33 pp. 1587-1587. 

Figure 8 shows the SEM micrographs of fracture surfaces of both HX-205 and F-185 neat resins. The fracture surface of HX-205 Is very smooth. Indicative of typical brittle fracture behavior. On the other hand, F-185 has a very rough fracture surface. Indicating that the resin was highly strained before fracture occurred. There are also some craters which appear to represent the separation of spheroidal rubber domains from the matrix. 

Figure 4.4 Temperature sensitivity of the fracture toughness K J of a polyester resin [38], , Smooth fracture surface O, rough fracture surface. Strain rate, 1mm min" ...

Complex geometry of pr erential flow paths (as afifected by rock discontinuity and heterogeneity on all scales—from a rough fracture surfece to an irregular fracture network). 

The crack plane in tension remained generally perpendicular to the direction of the applied load, without any deviation into the interlaminar plies. Oxidation of the composites did not change this general trend. SEM was performed on the tensile fracture surfaces to characterize the nature of the tensile failure. Micrographs of the fracture surfaces of the 5X and 8X as-prepared composites show a relatively rough fracture surface, but with very limited fiber pull-out. This corresponds well with the relatively low tensile failure strains of 0.2% seen in both of these composites. 

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