STABILITY OF NATURAL SLOPES ALONG THE TROPICAL COAST OF BRAZIL

Natural slopes in the tropical coast of Brazil range from rock scarps and residual soil to colluvial soils. Colluvium may cover residual as well as alluvial soil, this case being common at stretches of coasts adjacent to mountains, where an interdigitation of colluvium and alluvium can occur. The instabilization of these slopes in the long run derives mainly from the action of rainfall and from physical and chemical weathering of the parent rock. Chemical weathering breaks down the minimal constituents of the rock, reduces its strength, and is intensified by water percolating through fissures in the rock. For a given situation in time, rainfall has a direct influence on the mass movements, and according to its intensity and duration is the cause of landslides due to loss of apparent cohesion at the surface of residual and colluvial slopes, as well as deep seated movements due to the elevation of the phreatic level or artesian pressure. Other causes of instabilization of residual slopes are the impact due to the fall of rock slabs or earth masses from higher elevations which may cause sudden loss of strength and the initiation of debris-flows. Lightning also has been reported as the cause of landslide initiation, and should not be neglected. Some of these processes are discussed and examples taken from research at COPPE are shown illustrating relevant cases.

Language

  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 17-39

Subject/Index Terms

Filing Info

  • Accession Number: 00746454
  • Record Type: Publication
  • ISBN: 9054108851
  • Files: TRIS
  • Created Date: Mar 3 1998 12:00AM