Deep Patch Applications and Lessons Learned Through Case Histories

A deep patch is a landslide mitigation technique that consists of a subexcavation that is typically in the range of 3 to 6 feet deep backfilled with granular material and layers of geosynthetic reinforcement that are vertically spaced from 6- to 12-inches. The 12-inch maximum reinforcement spacing utilizes the geosynthetic reinforced soil (GRS) concept to create a composite structure. A deep patch utilizing the GRS concept has two or more layers of geosynthetic reinforcement at vertical spacings between 6 and 12 inches. The authors have found that 6-inch vertical spacing is usually most cost effective but 9- to 12-inch spacing is easier to construct. This paper summarizes lessons learned from three sites where a deep patch was used as mitigation over landslides that were larger and moving faster than traditional deep patch applications. These case histories all used deep patches with five to 7 layers of geogrid at 9-inch vertical spacing. The deep patches were all successful at slowing the development and propagation of larger landslide movement. The Agness Road case history demonstrates that even when the deep patch is effective at reducing movements, some displacement should still be anticipated in applications to fast moving landslides. This should be considered when deciding if whether a deep patch is an appropriate application.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; Photos; References;
  • Pagination: 12p

Subject/Index Terms

Filing Info

  • Accession Number: 01657854
  • Record Type: Publication
  • Report/Paper Numbers: 18-01099
  • Files: TRIS, TRB, ATRI
  • Created Date: Jan 8 2018 10:16AM