Environmental Engineering Reference
In-Depth Information
Ground Subsidence, Collapse, and Heave (Chapter 1 0)
Regional subsidence is caused by earthquakes, the extraction of water, oil, or gas, and sub-
surface mining operations. The result of subsidence can be flooding, faulting, and the dis-
tortion of structures.
Ground collapse results from subsurface mining operations, water table lowering in
cavernous soluble rocks, or the weakening of the intergranular structure of certain soil for-
mations. Surface structures can be lost, destroyed, or distorted.
Subsidence in soils results from leaching, internal erosion from piping, compression under
externally applied loads, or evaporation causing desiccation and shrinkage. It can cause the
distortion of surface structures and the collapse of earthen embankments and slopes.
Surface heave occurs on a regional basis as a result of tectonic forces, and on a local basis
from stress relief during excavation. The expansion of soil and rock, which can result from
swelling characteristics or frost, also contributes to surface heave. Expansion from
swelling or frost can result in the distortion of structures and the weakening of slopes.
Each of these phenomena is characteristic of certain environments and interfacing
elements and, therefore, is predictable. In many cases the most suitable treatment is their
prevention.
Earthquakes ( Chapter 1 1)
The elements of earthquakes include the energy source or cause, the position of the source
in the Earth (focus and epicenter), the seismic waves generated by the source, the ground
motion resulting from the waves, the characteristics of intensity and magnitude, and the
attenuation or amplification of the intensity.
Surface effects are numerous and include faulting, dynamic soil behavior (such as subsi-
dence and liquefaction), slope failures, tsunamis and seiches, and the shaking of structures.
Design studies require an evaluation of regional seismic risk, the identification of possi-
ble faults, the development of the design earthquake, and the selection of ground response
factors such as the acceleration due to gravity, frequency content, duration, and the influ-
ence of local soil conditions. Suitable treatment requires resistant design.
Volcanos are also considered in this chapter. In recent years, lahars have been recog-
nized as a major hazard to persons living even many kilometers away from a volcano.
1.2.5
Appendices
The Earth and Geologic History ( Appendix A): The Earth's crust and surface are
undergoing constant change, usually scarcely perceptible, as a result of global
tectonics. The nomenclature of geological history is useful for indexing forma-
tions and for making correlations between widely separated geographic loca-
tions. Ages are determined by radiometric dating, for which there are a number
of procedures.
USGS Quads, Aerial Photographs, Satellite and SLAR Imagery ( Appendix B):
USGS Quad Sheets and stereo-pairs of aerial photographs in this topic.
English to Metric to the International System ( Appendix C): Conversions from
English to metric to SI units and metric to English to SI units are given.
Symbols ( Appendix D): Symbols used in the text are summarized and identified.
Engineering Properties of Geologic Materials: Data and Correlations ( Appendix E):
A synopsis of the tables and figures from the text providing data and correlations
for rock, soil, and groundwater is presented. Rock and soil properties are keyed
to index or basic properties, compression, expansion, and strength.
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