Geologic Hazards - Geotechnical Engineering Investigation - page 771

Summary
The applicability of mathematical analysis to various slope failure forms and the ele-
ments affecting slope failures are summarized in Table 9.4. General methods of stability
analysis for sliding masses and the applicable geologic conditions are summarized in
Table 9.5. Strength parameters acting at failure under various field conditions are summa-
rized in Table 9.6.

9.3.3 Slope Characteristics

General
Qualitative assessment of slopes provides the basis for predicting the potential for failure
and selecting practical methods for treatment, and for evaluating the applicability of
mathematical solutions. The two major elements of qualitative assessment are slope char-
acteristics (geology, geometry, surface conditions, and activity) and the environment
(weather conditions of rainfall and temperature, and earthquake activity). The discussion
in Section 9.2 presents relationships between the mode of slope failure and geologic con-
ditions, as well as other slope characteristics, giving a basis for recognizing potential slope
stability problems.

TABLE 9.4
Comparison of Elements and Classification of Geological and Engineering Failure Forms

Elements of Slope Failures a Engineering Failure Forms b

Geologic Failure Forms

Falls P N P P P N NNNP N

Planar slides (translational P S P P P MAAAAN

block glides)
Rotational slides in rock P P P P P MNNNNA

Rotational slides in soil P P P P P MNNNNA

Lateral spreading and S M P P P N NS S NN

progressive failure
Debris slides P M P P P N S S S S N

Debris avalanches P S S S P P NNNNN

Debris flows P S S S P P NNNNN

Rock fragment flow P S P P P N NNNNN

Soil and mud flows S S S P P MNNNNN

Submarine slides S S P P P N NNNNS

a

P — primary cause; S — secondary cause; M — minor effect; N — little or no effect.

b

A — application; S — some application; P — poor application; N — no application.