Location

Arlington, Virginia

Session Start Date

8-11-2008

Session End Date

8-16-2008

Abstract

The successful operation of facilities that incorporate long electron-positron beams necessitates a very low vibration environment at the beam supports. Mitigation of the ground motion and imported vibration from the numerous vibrations sources is the main engineering challenge for these projects. Computer program SASSI was selected as an analysis tool for calculating the vibrations in underground tunnels resulting from near field sources due to equipment operation as well as far-field sources for a new generation of linear colliders. The program capabilities were validated by comparing calculated vibration results with field obtained measurements performed at the Los Angeles County Metropolitan Authority (MTA) Metro Red Line tunnels which consist of twin circular parallel tunnels that run through Miocene sandstone and shale. A 3D SSI model of a representative segment of the tunnels was developed. Analyses for three loading cases were performed simulating three tests that were done to characterize the transmission of vibrations from grade to a tunnel, 90 feet deep, transmission of vibrations inside one of the tunnels, and transmission of vibrations from one tunnel to the other tunnel. The maximum velocities, mobility functions, and displacement functions were calculated for each test case. The results were compared with available recorded data. Excellent agreement between SASSI results and recorded data for all three tests was obtained.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Sixth Conference

Publisher

Missouri University of Science and Technology

Publication Date

8-11-2008

Document Version

Final Version

Rights

© 2008 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Aug 11th, 12:00 AM Aug 16th, 12:00 AM

Calibration of Computer Program Sassi for Vibration Transmissibility Analysis in Underground Structures Using Field Measured Data

Arlington, Virginia

The successful operation of facilities that incorporate long electron-positron beams necessitates a very low vibration environment at the beam supports. Mitigation of the ground motion and imported vibration from the numerous vibrations sources is the main engineering challenge for these projects. Computer program SASSI was selected as an analysis tool for calculating the vibrations in underground tunnels resulting from near field sources due to equipment operation as well as far-field sources for a new generation of linear colliders. The program capabilities were validated by comparing calculated vibration results with field obtained measurements performed at the Los Angeles County Metropolitan Authority (MTA) Metro Red Line tunnels which consist of twin circular parallel tunnels that run through Miocene sandstone and shale. A 3D SSI model of a representative segment of the tunnels was developed. Analyses for three loading cases were performed simulating three tests that were done to characterize the transmission of vibrations from grade to a tunnel, 90 feet deep, transmission of vibrations inside one of the tunnels, and transmission of vibrations from one tunnel to the other tunnel. The maximum velocities, mobility functions, and displacement functions were calculated for each test case. The results were compared with available recorded data. Excellent agreement between SASSI results and recorded data for all three tests was obtained.