Instrumentation of New Dam Abutment Construction

The U.S. Army Corps of Engineers, Pittsburgh District, is in the process of replacing the aged concrete overflow dam at the Monongahela River No. 2 Locks. The new dam will be built using innovative-in-the wet construction techniques. The proposed dam will be assembled from pre-cast concrete members in a dry dock. This assembly will then be floated into position and set on a preconstructed drilled pier foundation system.

To verify design assumptions and to allow for monitoring of the new dam's performance, the Corps has incorporated the installation of an extensive instrumentation system into the dam's construction. The instrumentation system consists of the following components:
- Inclinometers, both manually read and permanent, in-place instruments
- Vibrating wire piezometers
- Vibrating wire strain gages
- Strain gage-type load cells
- Alignment pins
- An automatic data acquisition system

Construction of the proposed dam's abutments has just been completed. Excavation of soil from beneath the dam's footprint is now underway. The portion of the instrumentation system which addresses abutment performance is now operating and performance data is being collected and analyzed.

The proposed paper will contain the following:
- A description of the purpose of the instrumentation.
- A summary of the instruments and devices comprising the instrumentation system.
- A discussion of the system installation techniques.
- A description of the automatic data collection and reduction methodology
- A presentation of instrumentation system data and their implications.