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Is Field Monitoring During Retaining Wall Construction Really That Important?

08.17.15   Robert C. Rabeler, PE | More by this Author

Is Field Monitoring During Retaining Wall Construction Really That Important?

Geotechnical Engineering Lessons Learned from Failure: A Look at Retaining Wall Construction

This article is part of a series regarding lessons learned in geotechnical engineering. These are real projects with real people, but the names have been omitted to protect those involved.

A segmental block retaining wall was constructed on a shopping center site. Segmental blocks are cast-in-place concrete that are stacked on top of each other. They are kept in place either by their own weight or by lateral reinforcement behind the wall. For this project, the walls were designed using just the weight of the blocks. 

During construction the walls failed, as shown below:

After SME’s geotechnical engineer viewed the site and talked with the contractor, it became evident that the wall was not constructed as designed. Some of the blocks were smaller than specified in the design, and the slope behind the wall was not flattened as specified. A number of other details in the design were also not incorporated during construction. To fix the problem, the contractor removed the wall and reinstalled it, this time constructing it as designed. Building the wall twice was a costly mishap.

 

Lesson Learned: Altering design plans, even in seemingly insignificant ways, can result in failure. The cost of field monitoring would have been just a small fraction of the cost incurred to rebuild the wall. Careful monitoring of construction activities by a knowledgeable and experienced geotechnical engineer is a critical link to successful projects. Field representatives need to understand the nuances of design so that any changes made will not impact the project’s integrity.

For more information, contact Bob Rabeler.


TAGS: Geotechnical

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