Seismic on retaining wall

Although I am nopt familiar with Monokobe-Okabe equations I can tell you that the basics of restrained versus non-restrained retaining walls is that you should use different earth pressure conditions. For restrained retaining walls the coefficient of earth pressure should be that of the at-rest condition. For unrestrained retaining walls you should always use the coefficient of active earth pressure. Also, be sure you calculate the coefficient of active earth pressure using rankine theory since Coulombs theory was developed for gravity retaining walls.

Hope this helps! CIS Geotechnical
jrodriguez@centralindustrialpr.com

Hi,
The program doesn’t use the Monokobe-Okabe/See-Whitman for restrained walls because the formula for this methodology uses the active earth pressure conditions Ka. You want to calculate your earth pressures at rest Ko. And these conditions are not used in the equation for the program.

The question of how much seismic force will be exerted on the wall still remains. Kramer, in his book "Geotechnical Earthquake Engineering" has a section on retaining walls and presents some equations that are commonly used for your situation.

If you don't have access to Kramer, AASHTO recommended that nonyielding abutments be designed to resist lateral thrust obtained from the Mononobe-Okabe method with a pseudostatic horizontal acceleration 50% gretater than the effective peak acceleration.

Don't forget the inertia effects of the wall itself. Good luck.

I am not familiar with the Monokobe-Okabe equations, but under a seismic scenario, might it also not be possible under some circumstances to encounter liquifaction of some or all of the material behind the wall which could represent a different loading scenario from either ka or ko?