back to back MSE walls

[yaroosh]

Hello,

I am working on a back to back mse wall design. I read Berg explanation of the behavior of back to back mse wall for two cases. I am having some trouble understanding the effect on the active wedge. It seems from their explanation that if an active wedge is not fully developed then we need to reduce it. by how much should this reduction be?

I tried to look up for other resources and also on this forum to find more info, but didn't have any luck. If you could direct me to the right resource, it will be greatly appreciated!

Thank You!

 

[fattdad]

The active wedge is defined by an angle. As you work your way down the proposed wall, strike that angle vertically upward towards the other wall. When that angle hits the other wall, active earth pressures no longer increase and the envelope becomes a vertical line.

If you draw it, it's obvious.

f-d

ípapß gordo ainÆt no madre flaca!

 

[yaroosh]

Thank you for you response!

I was able to do that. I am confused because Berg says that if D (distance between walls) is less than H tan (45-phi/2) then the active wedge cannot be fully developed, hence the active thrust is reduced. However, from my understanding that if the full active pressure doesn't develop, then the pressure would be higher ( as in at rest condition). I feel both are contradicting. Why would the active thrust be reduced if the active wedge cannot be fully developed?

 

[fattdad]

the weight of a truncated triangle is less than the full triangle.

At rest is a larger triangle than active.

f-d

ípapß gordo ainÆt no madre flaca!