Sinking Retaining Wall

Sinking Soil Retaining Wall
Built at UW-Stout just East of Jarvis Hall during the Summer of '01.

During Construction (Before the wall started to sink.
(Pictures immediately below were taken in June, 2001.)



Masonry blocks used to construct the soil retaining walls.



Special geo-fabric used to help stabilize the soil behind the retaining wall.  There is minimal pressure being exerted against the wall with this design.  In fact, the blocks can sometimes be removed without the soil collapsing.  The geo-fabric cuts across the most probable slip surface.  This greatly reduces the probability of large pressures developing against the wall.  (The wall also serves to inhibit erosion.)



Notice the gravel for good drainage.  There is also a tile that runs the length of the wall on the fill side to assist the drainage.


Identification of the wall sinking (end of August, 2001)

Stout Parking Spaces Remain The Same, Dunn County News article, August 26, 2001
"...The opening of Lot 34, located at the intersection of 13th Ave. and 6th St., will be delayed indefinitely, due to a problem with a major retaining wall, which is sinking due to a layer of peat underneath."

Stout Community News, August 30, 2001

"...Although borings were performed on the site prior to the beginning of the project to analyze soil conditions, none were performed under the location of the wall.  As a result, the wall is now sinking due to a layer of peat that was later discovered."

Parking lot completion delayed, Stoutonia, October 4, 2001

"During a two week surveillance period, the wall sunk six inches -- five inches more than normal."

"They didn't take the soil bearings directly under where the wall was being built, said Gerald Drier, the Associate Director of the UW-Stout Physical Plant."

"Seven to nine feet below the topsoil is a layer of peat...(each brick in the wall weighed 78 pounds)...The estimated cost to fix the wall is $200,000, a fifth of the original cost of the $950,000 project."

"Since the contractor hired by the architecture firm was negligent, the firm has agreed to pay a large sum of the additional cost."



The soil beneath this new wall has differentially settled about 15 cm within 3 months of construction.  The pictures above show the North wall looking West.  The settlement is occuring in the Northwest corner.



The wall being dismantled.

Bill Kwazny, P.E. Presentation (September 25, 2001)



Some of Bill Kwazny's drilling tools.  Auger is on the right and a split-spoon sampler is in the middle.


Bill talking to the students.



The wall being dismantled.





Ray demonstrating the proper technique for using the nuclear densometer.


Equipment moving the pile of dirt to another location.