Multimode Rayleigh wave profiling by hybrid surface and borehole methods

Thumbnail Image
Date
2014-05-01
Authors
Lin, Shibin
Ashlock, Jeramy
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Authors
Person
Ashlock, Jeramy
Associate Professor
Research Projects
Organizational Units
Organizational Unit
Civil, Construction and Environmental Engineering

The Department of Civil, Construction, and Environmental Engineering seeks to apply knowledge of the laws, forces, and materials of nature to the construction, planning, design, and maintenance of public and private facilities. The Civil Engineering option focuses on transportation systems, bridges, roads, water systems and dams, pollution control, etc. The Construction Engineering option focuses on construction project engineering, design, management, etc.

History
The Department of Civil Engineering was founded in 1889. In 1987 it changed its name to the Department of Civil and Construction Engineering. In 2003 it changed its name to the Department of Civil, Construction and Environmental Engineering.

Dates of Existence
1889-present

Historical Names

  • Department of Civil Engineering (1889-1987)
  • Department of Civil and Construction Engineering (1987-2003)
  • Department of Civil, Construction and Environmental Engineering (2003–present)

Related Units

Journal Issue
Is Version Of
Versions
Series
Department
Civil, Construction and Environmental Engineering
Abstract

To improve the accuracy of shallow seismic shear wave velocity profiling, we propose a minimally invasive hybrid surface-and-borehole method that enhances the detection of higher modes of Rayleigh wave dispersion data. The new method combines techniques from the multichannel analysis of surface waves and multichannel simulation with one receiver (MSOR) methods to record components of Rayleigh wave motion at the surface as well as at shallow depths within the soil mass. The performance of the proposed method is demonstrated through computational and experimental studies. We show that individual modes of Rayleigh waves can exhibit different dominant depths at which their motion is most significant. This is demonstrated through a numerical study of eigenvectors of layered soil profiles via the stiffness matrix method, and confirmed by a finite element simulation of the apparent dispersion trends recorded at shallow depths using MSOR. Upon superimposing dispersion data recorded via the receivers at various depths, the resulting multimode dispersion data is used in a multi-objective inverse analysis, for which the difference between experimental and theoretical dispersive phase-velocity spectra are minimized for multiple modes simultaneously. In the numerical study, we demonstrate that the resulting inverted profiles and theoretical dispersion data have improved accuracy relative to single-mode inversion. Preliminary field tests are performed using the new hybrid method, and the results are shown to support the conclusions of the numerical study and confirm the feasibility of the proposed technique. Although the use of multiple modes in surface wave testing is not new, the proposed hybrid method can provide more accurate and complete multimodal dispersion data than achieved with surface-only Rayleigh wave methods. As a result, errors because of misidentification or partial measurement of higher modes may be minimized, thus reducing statistical uncertainty in the inverted profiles.

Comments

This article is from Geophysical Journal International 197 (2014): 1184–1195, doi:10.1093/gji/ggu051. Posted with permission.

Description
Keywords
Citation
DOI
Subject Categories
Copyright
Wed Jan 01 00:00:00 UTC 2014
Collections