Civil Engineering Reference
In-Depth Information
Total stress
Effective stress (
u
)
v
0
Vertical effective stress
5.1 INTRODUCTION
Part 2 of the topic describes the different types of geotechnical earthquake engineering
analyses. Specific items included in Part 2 are as follows:
●
Site investigation for geotechnical earthquake engineering (Chap. 5)
●
Liquefaction (Chap. 6)
●
Settlement of structures (Chap. 7)
●
Bearing capacity (Chap. 8)
●
Slope stability (Chap. 9)
●
Retaining walls (Chap. 10)
●
Other earthquake effects (Chap. 11)
It is important to recognize that without adequate and meaningful data from the site
investigation, the engineering analyses presented in the following chapters will be of doubt-
ful value and may even lead to erroneous conclusions. In addition, when performing the site
investigation, the geotechnical engineer may need to rely on the expertise of other special-
ists. For example, as discussed in this chapter, geologic analyses are often essential for
determining the location of active faults and evaluating site-specific impacts of the design
earthquake.
The purpose of this chapter is to discuss the site investigation that may be needed for
geotechnical earthquake engineering analyses. The focus of this chapter is on the informa-
tion that is needed for earthquake design, and not on the basic principles of subsurface
exploration and laboratory testing. For information on standard subsurface exploration and
laboratory testing, see Day (1999, 2000).
In terms of the investigation for assessing seismic hazards,
Guidelines for Evaluating
and Mitigating Seismic Hazards in California
(Division of Mines and Geology 1997)
states: “the working premise for the planning and execution of a site investigation within
seismic hazard zones is that the suitability of the site should be demonstrated. This
premise will persist until either: (a) the site investigation satisfactorily demonstrates the
absence of liquefaction or landslide hazard, or (b) the site investigation satisfactorily
defines the liquefaction or landslide hazard and provides a suitable recommendation for
its mitigation.” Thus the purpose of the site investigation should be to demonstrate the
absence of seismic hazards or to adequately define the seismic hazards so that suitable
recommendations for mitigation can be developed. The scope of the site investigation is
discussed next.
5.1.1
Scope of the Site Investigation
The scope of the site investigation depends on many different factors such as the type of
facility to be constructed, the nature and complexity of the geologic hazards that could
impact the site during the earthquake, economic considerations, level of risk, and specific
requirements such as local building codes or other regulatory specifications. The most
