Concrete cutoff walls

Concrete Cutoff walls

Concrete cutoff walls are cast-in-place structures. They are used to provide a positive cutoff of the flow of water under or around a hydraulic structure, such as a dam. Geotechnical monitoring and review prior to making a decision to build a cutoff wall is prudent.

The average cutoff wall is between 2 to 4 feet thick. The procedure for preparing for and creating a cutoff wall can be tricky. A concrete-lined guide trench is made along the axis of the wall to be repaired. This type of trench is usually only a few feet deep. This gives a working service on both sides of the wall and helps to maintain the alignment of the wall.

Concrete is placed in the trench to create the cutoff wall. Discontinuities in the concrete can cause serious performance problems and must be screened for. The concrete mixture is very important. It will be used for tremie placement, and this requires strict adherence to required  specifications . You are not looking for compressive strength. The key elements are flow ability and cohesion.

Test panels should be created in noncritical locations near the wall location. These panels can then be tested to determine if the concrete mixture and the placement process is providing the desired result.