Cracks in the Classroom: Our Geoforensic Investigation of a Failing South Texas School

Building Failure 

My Geotechnical Firm performed a Geoforensic investigation of a School in South Texas.

Drilled piers were to be built according to the above design. All piers would be constructed at a depth of 13’.

They dug investigation holes at several of the piers and found that they were not constructed according to the design. Pier depths were measured at 10’6” instead of the design depth of 13’. The Bell size was constructed at 36” instead of the design of 78”. The Shaft diameter was constructed at 18” instead of the design of 30”.

They also found that the fill under the slab was highly expansive with a PI (Plastic Index) of 32-40.

In their review of the expansive soil, they determined that the PVR (Potential Vertical Rise) is 3.6”. Therefore, the original design of a 13’ depth was not sufficient to resist the uplift loads due to the expansive soils. The minimum depth should have been a minimum of 25’.

They also found negative drainage on the east and west sides of the building. The roof drain was depositing rainwater directly onto the sidewalk near the foundation.

Summary;

1) Inadequate design of the piers, due to the uplift capacity, the piers should have been constructed to a 25’ depth.

2) Improper construction of existing piers, they were constructed at 10’6” depth instead of the designed 13’.

3)  Poor foundation maintenance with negative drainage.

4) Roof drains depositing directly on top of the sidewalk.

To significantly reduce the risk of costly failures on your next building project, ensure that your Construction Manager or General Contractor has a QC (Quality Control) program and that they adhere to it, as we do here at Shettig Construction Management. 

I wish you success on your project.

 Shettig Construction Management provides Professional Construction Management services from the inception of your project through completion. www.shettig.com

mshettig@gmail.com