Environmental Engineering Reference
In-Depth Information
2nd Application
shotcrete
1st Application
shotcrete
Geocomposite
drainage strip
Wire mesh
2nd Stage grout
A
Nail
I
6
1st Stage
grout
5˚ (typ.)
Mortar pack
to contain
2nd stage
grout
Shortcrete and nailing detail
6"
Geocomposite
drainage strip
Nail
FIGURE 9.124
Retention with shotcrete and nails or bolts in soil
or rock.
Section A-A
prone to slope failures, and the type, magnitude, and probability of occurrence. Hazard
maps illustrate the findings.
Individual Slopes
Individual slopes are studied when signs of instability are noted and development is endan-
gered, or when new cuts and fills are required for development. Studies should be per-
formed in two phases: Phase 1, to establish the overall stability, is a study of the entire slope
from toe to crest to identify potential or existing failure forms and their failure surfaces, and
Phase 2 is a detailed study of the immediate area affected by the proposed cut or fill.
Considerations
Failure Forms and Hazard Degrees
Engineers and geologists must be aware of which natural slope conditions are hazardous,
which can be analyzed mathematically with some degree of confidence, which are very
sensitive to human activities on a potentially catastrophic scale, which can be feasibly con-
trolled, and which are to be avoided. They should also be aware that in the present state
of the art there are many limitations in our abilities to predict, analyze, prevent, and con-
tain slope failures.
Rotational slides are the forms most commonly anticipated, whereas the occurrence of
other forms is often neglected during slope studies. They are generally the least catastrophic
of all forms, normally involve a relatively small area, give substantial warning in the form
of surface cracking, and usually result in gradual downslope movement during the initial
development stages. Several potential failure forms can exist in a given slope, however.
