Environmental Engineering Reference
In-Depth Information
Postconstruction
After construction has been completed, stresses and deformations may be monitored to
provide an early warning against possible failure of slopes, retaining structures, earth
dams, or concrete dams with rock foundations and abutments.
Existing Structures
Structures undergoing settlement are monitored to determine if and when remedial meas-
ures will be required and how stability will be achieved.
Instrumentation is installed to monitor the effects on existing structures of (1) dynamic
loadings from earthquake forces, vibrating machinery, nearby blasting or other construc-
tion operations; and (2) deformations resulting from nearby tunneling or open excavations.
Slopes
Instrumentation is installed to monitor movements of rock and soil slopes, to locate fail-
ure surfaces and monitor their deflections, and to monitor groundwater conditions.
Mineral Extraction
The extraction of oil, gas, water, coal, or other minerals from the subsurface can result in
surface deformations that require monitoring, as discussed in
sections 10.2
and
10.3.
Tectonic Movements
In areas of crustal activity, movements and stresses related to surface warping and fault-
ing are monitored as discussed in
section 11.3.1.
4.1.4
Program Elements
General
In planning an instrumentation program, the initial steps involve determining what quan-
tities should be measured and selecting the instrument or instruments. The choice of
instruments requires consideration of a number of factors, followed by a design layout of
the instrumentation arrays for field installation.
Execution requires installation and calibration, data collection, recording, processing,
and interpretation.
Instrumentation Selection
Conditions to be Monitored
Instrumentation types and methods are generally grouped by the condition that has to be
monitored, i.e., surface movements, subsurface deformation, and
in situ
pressures and
stresses.
Application
Instruments vary in precision, sensitivity, reliability, and durability. The relative impor-
tance of these factors varies with the application or purpose of the program, such as col-
lecting design data or monitoring construction and postconstruction works, existing
structures, or the effects of mineral extraction or tectonic activity.
