GEOTECHNICAL INSTRUMENTATION NEWS
Summary of instruments that can be considered for helping to provide answers to possible geotechnical questions
Table 2 lists the possible geotechnical questions that may lead to the use of instrumentation for externally braced excavations,
together with possible instruments that can be considered for helping to provide answers to those questions.
Table 2. Some instruments that can be considered for monitoring externally braced excavations
Possible geotechnical questions
Measurement
Some instruments that can be considered
What are the initial site conditions?
As in Table 1
As in Table 1
What is a suitable design for tieback
anchors (by constructing and
testing
test anchors
)?
Load in tieback
Displacement at head
Load transfer in grouted zone
Load cells
Dial indicators
Surface-mounted strain gauges
Are the tiebacks being installed
correctly (by
performance
and
proof
testing
)?
Load in tieback
Displacement at head
Calibrated hydraulic jacks
(Load cell)
Dial indicators
Is the excavation stable, and are nearby
structures being affected adversely
by ground movement?
As in Table 1, except for load in
struts
Load in tieback
As in Table 1, except for load in struts
Load cells
(Calibrated hydraulic jacks and load cells:
lift-off tests
)
Surface-mounted strain gauges
Is the groundwater table being
lowered?
As in Table 1
As in Table 1
Is excessive bottom heave occurring? As in Table 1
As in Table 1
