This study was initiated to investigate moisture movement in natural shale cuts and shale embankments on roadways located in the expansive Pierre Shale areas of Western South Dakota. The following items were studied: (1) moisture changes that take place in cut sections and embankments constructed in Pierre Shale; (2) physical character of undisturbed Pierre Shale; (3) source of free water accumulation in Pierre Shale; and (4) investigation of remedial measures to control the movement of moisture into the cut section and fill sections of roadways built in Pierre Shale. Ten permanent surveillance test holes were installed in selected cut sections and fill sections on a portion of Interstate Route 90, near Rapid City, South Dakota, which had been completed and was open to traffic. The holes were located in an area where warping and severe heaving had taken place. The moisture variations in the test holes were monitored by a radioactive nuclear logging device. Ten companion water well holes were placed opposite the nuclear holes, above the toe of the inslope in the cut and fill sections, to detect changes in the free water movement that may have taken place in the deep portions of the cut sections and under the fills. Two resistivity and seismic surveys were made during the course of the study for the purpose of correlating the data from the nuclear test holes and the water well holes and to develop a method of finding potential trouble areas with a minimum amount of drilling. The study indicated that the water levels in the individual test sites varied considerably from month to month. The nuclear moisture density devices also showed variable moistures and densities in the subgrade directly under the surfacing materials. The free water, which was present in the open jointed shale cut and fill sections, was directly related to the surface water equivalent, (rain and/or snow), and collected in the lower areas of the roadbed in proportion to the amount of surface water available. The amount of water accumulation under the fills was much lower than in the cuts and appeared to be developed from the moisture that filtered in from adjacent cut sections ahead or back of the fill. It appeared that the severe warping condition which was associated with the conditions described above could be reduced to some agree by placing special subsurface drainage systems in all cut sections which exhibited faulting. A redesigned ditch section, which would facilitate a fast runoff of surface water, would also be beneficial. Other techniques, such as a catalytic asphalt blanket and plastic membrane cut off wall, could also be used.

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: 37 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00081848
  • Record Type: Publication
  • Report/Paper Numbers: Final Rpt.
  • Created Date: Mar 26 1975 12:00AM