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|Title:||Installation of pipelines beneath levees using horizontal directional drilling|
|Authors:||O'Donnell Associates, Inc.|
Construction Productivity Advancement Research Program (U.S.)
Bennett, Robert D.
O'Donnell, Hugh W.
Hurley, Timothy J.
Horizontal directional drilling
|Publisher:||Geotechnical Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
Abstract: Three horizontal directionally drilled bores were completed beneath a Mississippi River levee near Vicksburg, MS. Operating parameters were varied in a controlled fashion and ground conditions were carefully documented. Changes in pore pressures were monitored before, during, and after installation to help assess impacts on stability. Internal and external drilling fluid pressures were continuously monitored. An exhaustive autopsy was conducted by excavating down to the installed pipelines to determine the zone of influence around the pipelines created by the drilling fluids. Dye tracers were added to the drilling fluids to allow visual determination of fluid migration. Important conclusions from this investigation were that regardless of the internal drilling fluid pressures measured at the nozzle, which ranged from 10.6 to 24.7 kg/cm² (150 to 350 psi), the external drilling fluid pressures, measured in the annular space 0.305 m (1 ft) behind the nozzle remained within a narrow range of 3.3 to 3.7 kg/cm² (47 to 52 psi), or 15 to 31 percent of the internal pressures. The increases in piezometric pressures were less than 1 percent of these external pressures, and less than 0.2 percent of the internal pressures. These small increases in pressures should be of no concern with regard to levee stability.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Technical Report|