Theme 3: The Business Side of Instrumentation - Staged Embankment Construction Using In-Situ Instrumentation Returns Benefits To Contractor and Cost Savings to the Owner.

摘要

The Piedmont Triad International Airport (PTIA) is undergoing an expansion including a new runway (Runway 5L-23R) and taxiway (Taxiway E) as a result of the construction of a regional hub for Federal Express. Part of the construction of the associated Taxiway E includes the construction of the embankment over a wetlands area in an alluvial floodplain. The presence of soft ground in the wetlands area required careful consideration of the effects of construction, due to permitting requirements. An instrumentation program was implemented to determine the fill placement rates or appropriate waiting periods during fill placement, and to prevent slope failures from occurring. This paper highlights key features of the instrumentation system. It describes the instrumentation system that was installed, the results obtained to date, and practical issues that were addressed during construction. The grading plans for the project indicate the construction of an 18 meters (60-feet) high earth embankment over the existing soft ground. The subsurface exploration indicated the soft ground profile to consist of an upper zone of alluvial soil underlain by a residual soil profile. A hybrid ground modification technique was used to stabilize the soft ground, allowing construction of the Taxiway E embankment without more intensive efforts. The use of ground stabilization to provide a working platform in conjunction with toe berms to maintain slope stability and wick drains to accelerate drainage, strength gain, and settlement offered benefits to all members of the project team. The instrumentation program resulted in both material and time savings, by allowing for the modification of the design based on field conditions, and reducing or eliminating the waiting periods between fill placement phases.