GEO is monitoring a 32-foot deep excavation and a WMATA metro tunnel adjacent to the excavation in Washington DC.
The SOE consists of drilled soldier piles braced with whalers and rakers. GEO’s technician can be seen on the wall.
Monitoring prisms, a few visible in this photo, are mounted at the top of each pile around the entire perimeter of the excavation.
One wall of the excavation is located within 33 feet of a WMATA metro tunnel. The tunnel alignment is shown in blue.
The spatial positions of the prisms are measured by two AMTS. Changes in the position of a prism indicate movement.
GEO’s AMP server processes the measurements, checks for alarm conditions, and makes the data available on a project website.
GEO is also monitoring the WMATA tunnel near the site. Above, you can see the reflections from prisms mounted on the tracks, springlines, and crown of the tunnel.
This AMP plan view shows a 350 foot span of the tunnel along with XYZ displacements calculated from measurements from each prism.