Purpose This study develops an analytical framework for Rayleigh-wave propagation in a pre-stressed, doubly layered crustal configuration featuring orthotropic behaviour, small-amplitude corrugation of both the free surface and the internal interface, and imperfect interfacial bonding. The research specifically investigates how features such as anisotropy, corrugations, loose bonding, irregularity, and void porosity affect surface wave propagation. This integrated approach enables a more realistic representation of the Earth's crust. The novelty lies in quantitatively assessing how the coalesced presence of these structural irregularities and material characteristics influences Rayleigh wave velocity and displacement profiles, providing insights that cannot be captured by idealised models. Methods To analyse wave propagation, time-harmonic fields are employed and transformed using exponential/Helmholtz operators to obtain displacement solutions in each medium. An infinitesimally thin viscous interlayer is adopted to represent the interface, enabling a unified treatment of welded, loosely bonded, and smooth contact as limiting cases. The boundary conditions on corrugated surfaces and the imperfect interface are enforced to derive a determinant-form frequency equation and validated by comparison with existing literature. Results Parametric investigations through numerical simulation quantify the influence of initial stress, orthotropy, void fraction, corrugation amplitude and wavelength, and bonding strength on Rayleigh-wave dispersion. Conclusions Parametric results indicate that wave velocity decreases with increasing wavenumber, while interface irregularities, bonding strength, and material parameters such as initial stress and sandiness distinctly influence wave dispersion. Stronger interfacial coupling enhances wave speeds and reduces dispersion differences, whereas weaker bonding and increased void content diminish velocity and increase sensitivity to interface slip. Corrugation amplitudes and irregularity geometry further modulate phase velocities, especially at shorter wavelengths. This comprehensive approach improves understanding of seismic wave behaviour in complex geological media and offers valuable insights for geophysical site characterization, earthquake engineering, and non-destructive evaluation.

Rayleigh Wave Dynamics in Pre-Stressed Layered Crust with Complex Boundary Irregularities

期刊论文
发表日期：

2025年11月17日

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Pato Kumari,
Payal

摘要

Purpose

This study develops an analytical framework for Rayleigh-wave propagation in a pre-stressed, doubly layered crustal configuration featuring orthotropic behaviour, small-amplitude corrugation of both the free surface and the internal interface, and imperfect interfacial bonding. The research specifically investigates how features such as anisotropy, corrugations, loose bonding, irregularity, and void porosity affect surface wave propagation. This integrated approach enables a more realistic representation of the Earth's crust. The novelty lies in quantitatively assessing how the coalesced presence of these structural irregularities and material characteristics influences Rayleigh wave velocity and displacement profiles, providing insights that cannot be captured by idealised models.

Methods

To analyse wave propagation, time-harmonic fields are employed and transformed using exponential/Helmholtz operators to obtain displacement solutions in each medium. An infinitesimally thin viscous interlayer is adopted to represent the interface, enabling a unified treatment of welded, loosely bonded, and smooth contact as limiting cases. The boundary conditions on corrugated surfaces and the imperfect interface are enforced to derive a determinant-form frequency equation and validated by comparison with existing literature.

Results

Parametric investigations through numerical simulation quantify the influence of initial stress, orthotropy, void fraction, corrugation amplitude and wavelength, and bonding strength on Rayleigh-wave dispersion.

Conclusions

Parametric results indicate that wave velocity decreases with increasing wavenumber, while interface irregularities, bonding strength, and material parameters such as initial stress and sandiness distinctly influence wave dispersion. Stronger interfacial coupling enhances wave speeds and reduces dispersion differences, whereas weaker bonding and increased void content diminish velocity and increase sensitivity to interface slip. Corrugation amplitudes and irregularity geometry further modulate phase velocities, especially at shorter wavelengths. This comprehensive approach improves understanding of seismic wave behaviour in complex geological media and offers valuable insights for geophysical site characterization, earthquake engineering, and non-destructive evaluation.