Analytical study of S-wave propagation across saturated joints in rock masses

Geophysics ◽  
2009 ◽  
Vol 74 (5) ◽  
pp. E205-E214 ◽  
Author(s):  
Minsu Cha ◽  
Gye-Chun Cho ◽  
J. Carlos Santamarina

Field data suggest that stress level and joint condition affect shear-wave propagation in jointed rock masses. However, the study of long-wavelength propagation in a jointed rock mass is challenging in the laboratory, and limited data are available under controlled test conditions. Long-wavelength P-wave and S-wave propagation normal to joints, using an axially loaded jointed column device, reproduces a range of joint conditions. The effects of the normal stress, loading history, joint spacing, matched surface topography (i.e., joint roughness), joint cementation (e.g., after grouting), joint opening, and plasticity of the joint filling on the P-wave and S-wave velocities and on S-wave attenuation are notable. The ratio [Formula: see text] in jointed rock masses differs from that found in homogeneous continua. The concept of Poisson’s ratio as a function of [Formula: see text] is unwarranted, and [Formula: see text] can be interpreted in terms of jointed characteristics. Analytic models that consider stress-dependent stiffness and frictional loss in joints as well as stress-independent properties of intact rocks can model experimental observations properly and extract joint properties from rock-mass test data. Thus, joint properties and normal stress have a prevalent role in propagation velocity and attenuation in jointed rock masses.


2006 ◽  
Vol 48 (10) ◽  
pp. 1940-1943 ◽  
Author(s):  
Shinya Watanabe ◽  
Youichi Kakuta ◽  
Osamu Hashimoto

Author(s):  
Pulkit Kumar ◽  
Moumita Mahanty ◽  
Abhishek Kumar Singh ◽  
Amares Chattopadhyay

2020 ◽  
Vol 223 (2) ◽  
pp. 1118-1129
Author(s):  
Mohammad Mahdi Abedi ◽  
Alexey Stovas

SUMMARY In exploration seismology, the acquisition, processing and inversion of P-wave data is a routine. However, in orthorhombic anisotropic media, the governing equations that describe the P-wave propagation are coupled with two S waves that are considered as redundant noise. The main approach to free the P-wave signal from the S-wave noise is the acoustic assumption on the wave propagation. The conventional acoustic assumption for orthorhombic media zeros out the S-wave velocities along three orthogonal axes, but leaves significant S-wave artefacts in all other directions. The new acoustic assumption that we propose mitigates the S-wave artefacts by zeroing out their velocities along the three orthogonal symmetry planes of orthorhombic media. Similar to the conventional approach, our method reduces the number of required model parameters from nine to six. As numerical experiments on multiple orthorhombic models show, the accuracy of the new acoustic assumption also compares well to the conventional approach. On the other hand, while the conventional acoustic assumption simplifies the governing equations, the new acoustic assumption further complicates them—an issue that emphasizes the necessity of simple approximate equations. Accordingly, we also propose simpler rational approximate phase-velocity and eikonal equations for the new acoustic orthorhombic media. We show a simple ray tracing example and find out that the proposed approximate equations are still highly accurate.


1988 ◽  
Vol 24 (3) ◽  
pp. 234-238 ◽  
Author(s):  
V. A. Virchenko ◽  
S. V. Krasavin ◽  
S. V. Tsirel

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