Location

San Diego, California

Session Start Date

3-26-2001

Session End Date

3-31-2001

Abstract

Earthquake shaking causes the pore water pressure inside the soil mass to increase rabidly within a short period of time as seconds. As a result, the shear strength of the soil could be reduced significantly. The reduction in the shear strength will increase gradually as the shaking continues due to the gradual increase in the buildup of the excess pore water pressure. At a certain level of shaking, the soil mass will liquefy and could be considered as a viscous fluid. In this paper, a mathematical expression of a reduction factor was derived to estimate the reduction in the shear strength due to the buildup of the excess pore water pressure. This reduction factor represents the ratio of the effective shear strength of the soil at a certain level of shaking and the effective static shear strength. Using Mhor’s failure criteria, the shear strength at a certain level of shaking was calculated as a function of the applied horizontal and vertical acceleration coefficients produced by the earthquake shaking at the desired value of excess pore water pressure. The reduction factor was compared with some of the available dynamic triaxial and shaking table data. It was found that the derived relationship gives a good prediction of the reduction in the shear strength until the stage of liquefaction is reached. As an application, the derived expression can be used in determining the reduction in the bearing capacity at any suggested level of excess pore water pressure using certain coefficients of acceleration.

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

Shear Strength Reduction Due to Excess Pore Water Pressure

San Diego, California

Earthquake shaking causes the pore water pressure inside the soil mass to increase rabidly within a short period of time as seconds. As a result, the shear strength of the soil could be reduced significantly. The reduction in the shear strength will increase gradually as the shaking continues due to the gradual increase in the buildup of the excess pore water pressure. At a certain level of shaking, the soil mass will liquefy and could be considered as a viscous fluid. In this paper, a mathematical expression of a reduction factor was derived to estimate the reduction in the shear strength due to the buildup of the excess pore water pressure. This reduction factor represents the ratio of the effective shear strength of the soil at a certain level of shaking and the effective static shear strength. Using Mhor’s failure criteria, the shear strength at a certain level of shaking was calculated as a function of the applied horizontal and vertical acceleration coefficients produced by the earthquake shaking at the desired value of excess pore water pressure. The reduction factor was compared with some of the available dynamic triaxial and shaking table data. It was found that the derived relationship gives a good prediction of the reduction in the shear strength until the stage of liquefaction is reached. As an application, the derived expression can be used in determining the reduction in the bearing capacity at any suggested level of excess pore water pressure using certain coefficients of acceleration.