Location

San Diego, California

Session Start Date

3-26-2001

Session End Date

3-31-2001

Abstract

The New Madrid Seismic Zone, the most seismically active zone in the Eastern US, is overlain by deep unconsolidated deposits of the Mississippi Embayment. The deposits range in thickness from about 20 m in the St. Louis area to about 1 km in the Memphis Area and consist of silts, clays and sands. The influence of these deposits on the propagation of seismic waves to the ground surface remains a major source of uncertainty. A new non-linear one-dimensional site response analysis model is introduced for the vertical propagation of horizontal shear waves in deep soil deposits. The model accounts for the effect of large confining pressures on the strain dependent modulus degradation and damping of the soil. The capability of the new model is illustrated using soil columns at three typical locations within the Mississippi Embayment including a 1000 m column representative of conditions in Memphis. The analyses show that high frequency components usually filtered using conventional wave propagation methods, are preserved. The analyses show that spectral amplification factors for the deep deposits in the period range of 0.6-5sec range between 2 and 6, and at longer long periods (up to 10 set) can be as high as 8.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Meeting Name

Fourth Conference

Publisher

University of Missouri--Rolla

Publication Date

3-26-2001

Document Version

Final Version

Rights

© 2001 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Mar 26th, 12:00 AM Mar 31st, 12:00 AM

Non-Linear Site Response Analysis for Deep Deposits in the New Madrid Seismic Zone

San Diego, California

The New Madrid Seismic Zone, the most seismically active zone in the Eastern US, is overlain by deep unconsolidated deposits of the Mississippi Embayment. The deposits range in thickness from about 20 m in the St. Louis area to about 1 km in the Memphis Area and consist of silts, clays and sands. The influence of these deposits on the propagation of seismic waves to the ground surface remains a major source of uncertainty. A new non-linear one-dimensional site response analysis model is introduced for the vertical propagation of horizontal shear waves in deep soil deposits. The model accounts for the effect of large confining pressures on the strain dependent modulus degradation and damping of the soil. The capability of the new model is illustrated using soil columns at three typical locations within the Mississippi Embayment including a 1000 m column representative of conditions in Memphis. The analyses show that high frequency components usually filtered using conventional wave propagation methods, are preserved. The analyses show that spectral amplification factors for the deep deposits in the period range of 0.6-5sec range between 2 and 6, and at longer long periods (up to 10 set) can be as high as 8.