Compressional waves guided between parallel fractures

✍ Scribed by Xian, Changjiu ;Nolte, D.D ;Pyrak-Nolte, L.J

• Book ID: 104408615
• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 678 KB
• Volume: 38
• Category: Article
• ISSN: 0148-9062
• DOI: 10.1016/s1365-1609(01)00041-7

✦ Synopsis

We have performed experiments on the laboratory scale to image seismic wavefronts of compressional waves that are guided between parallel fractures. The wavefronts are detected using water-coupled 1 MHz piezoelectric transducers. The stiffness of the fractures is controlled by applying radial stress in a hydraulic stress apparatus that leaves the observation face of the fractured sample open to measurement. The two fractures form a waveguide in isotropic homogeneous aluminum and act as parallel displacement-discontinuity boundary conditions separated by a distance dE2l: The compressional wave is a leaky guided mode that sheds energy into the medium beyond the fractures. However, the fractures provide sufficiently strong energy confinement inside the central waveguide for a sample length L of approximately LE15l to observe the guided wave. Fractures with low fracture specific stifffness produce strong energy confinement in the guided compressional-mode wave.