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Geotechnical Engineering

 

Checklist and Guidelines for Review of Geotechnical
Reports and Preliminary Plans and Specifications

GTR Review Checklist for Landslide Corrections

 

D. Landslide Corrections

 (Pgs. 5-1 to 5-4, 5-17 to 5-20)

In addition to the basic information listed in Section A, is the following information provided in the landslide study geotechnical report? (Refer to Table 4 for guidance on the necessary technical support data for correction of slope instabilities.)

  1. *Is a site plan and scaled cross-section provided showing ground surface conditions both before and after failure?

        (Yes   /   No   /   Unknown or N/A)

  2. *Is the past history of the slide area summarized, including movement history, summary of maintenance work and costs, and previous corrective measures taken, if any?

        (Yes   /   No   /   Unknown or N/A)

  3. *Is a summary given of results of site investigation, field and lab testing, and stability analysis, including cause(s) of the slide?

        (Yes   /   No   /   Unknown or N/A)

Plan
  1. Are detailed slide features, including location of ground surface cracks, head scarp, and toe bulge, shown on the site plan?

        (Yes   /   No   /   Unknown or N/A)

Cross-section
  1. *Are the cross-sections used for stability analysis included with the soil profile, water table, soil unit weights, soil shear strengths, and failure plane shown as it exists?

        (Yes   /   No   /   Unknown or N/A)

  2. Is slide failure plane location determined from slope indicators?

        (Yes   /   No   /   Unknown or N/A)

  3. *For an active slide, was soil strength along the slide failure plane back-calculated using a F.S. = 1.0 at the time of failure?

        (Yes   /   No   /   Unknown or N/A)

Text
  1. *Is the following information presented for each proposed correction alternative (typical correction methods include buttress, shear key, rebuild slope, surface drainage, subsurface drainage-interceptor, drain trenches or horizontal drains, etc.).

    1. Cross-section of proposed alternative?

          (Yes   /   No   /   Unknown or N/A)

    2. Estimated safety factor?

          (Yes   /   No   /   Unknown or N/A)

    3. Estimated cost?

          (Yes   /   No   /   Unknown or N/A)

    4. Advantages and disadvantages?

          (Yes   /   No   /   Unknown or N/A)

  2. Is recommended correction alternative(s) given that provide a minimum F.S. = 1.25?

        (Yes   /   No   /   Unknown or N/A)

  3. If horizontal drains are proposed as part of slide correction, has subsurface investigation located definite water bearing strata that can be tapped with horizontal drains?

        (Yes   /   No   /   Unknown or N/A)

  4. If a toe counterberm is proposed to stabilize an active slide has field investigation confirmed that the toe of the existing slide does not extend beyond the toe of the proposed counterberm?

        (Yes   /   No   /   Unknown or N/A)

Construction considerations
  1. Where proposed correction will require excavation into the toe of an active slide (such as for buttress or shear key) has the "during construction backslope F.S." with open excavation been determined?

        (Yes   /   No   /   Unknown or N/A)

  2. If open excavation F.S. is near 1.0, has excavation stage construction been proposed?

        (Yes   /   No   /   Unknown or N/A)

  3. Has seasonal fluctuations of groundwater table been considered?

        (Yes   /   No   /   Unknown or N/A)

  4. Is stability of excavation backslope to be monitored?

        (Yes   /   No   /   Unknown or N/A)

  5. Are special construction features, techniques and materials described and specified?

        (Yes   /   No   /   Unknown or N/A)

*A response other than (yes) or (N/A) for any of these checklist questions is cause to contact the appropriate geotechnical engineer for a clarification and/or to discuss the project.

 

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Updated: 04/07/2011
 

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