PONDING AN EXPANSIVE CLAY CUT: EVALUATIONS AND ZONES OF ACTIVITY

The use of ponding water on a clay subgrade of high swelling potential to cause soil heaves before pavement was successful on an expressway project outside San Antonio, Texas. Expansive soils are a worldwide problem and cause over $2 billion damages/year in the United States. Their effectiveness of controlling the clay was measured, and the depth of the movements was determined. Observations began in 1968 and continued through 1976, both inside and outside the ponded area. The elevation rods were set at depths of 0.6 to 5.8 m (2 to 19 ft), and the moisture measurements were taken in the same zones. The ponding generally resulted in an upward movement of the elevation rods. The maximum movement was that of the shallower set rods in all areas. It now exceeds 0.12 m (0.42 ft) in the area where the predicted vertical rise is 0.15 m (0.5 ft). The moisture variations were greatest at depths up to 3 m (10 ft), where the rods exhibited maximum movement. This was the zone of activity. Pavements in the ponded ares have shown less distress and less major cracking and have required less major maintenance work than those in the nonponded areas. The relation of rainfall measurements to rod movements is not definiteve. A trend may be developing that shows upward movement to follow rainfall after prolonged dry periods. Ponding does seem to help curb the destructive movements of expansive clays.

Media Info

  • Media Type: Print
  • Features: Figures; References;
  • Pagination: pp 61-66
  • Monograph Title: Stabilization of soils
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00177120
  • Record Type: Publication
  • ISBN: 0309026709
  • Files: TRIS, TRB
  • Created Date: Jun 28 1978 12:00AM