Geokon 4430, Инструкция по эксплуатации, Страница: 20 / 24

14
The gauge length correction (L
C
) is calculated using Equation 5.
L
C
= 17.3 × 10-6 × L × (T
1
- T
0
)
Equation 5 - Gauge Length Correction
Where L is the length of deformation meter in millimeters or inches, minus the transducer length
(see Table 2), in millimeters or inches, respectively.
Consider the following example using a Model 4430 Deformation Meter with a one meter gauge
length and 25 mm transducer. Taken from the calibration sheet shown in Figure 10:
R
0
= 4250 digits
R
1
= 6785 digits
T
0
= 10 °C
T
1
= 20 °C
G = 0.004457 mm/digit
K = ((6785 × 0.000369) + 0.572) × 0.004457 = 0.0137
L = 1000 - 267 = 733
L
C
= 17.3 × 10-6 × 733 × (20 - 10) = 0.1268
Dcorrected = ((R
1
- R
0
) × G) + ((T
1
- T
0
) × K) + L
C
Dcorrected = ((6785 - 4250) × 0.004457) + ((20 - 10) × 0.0137) + 0.1268
Dcorrected = (2535 × 0.004457) + (10 × 0.0137) + 0.1268
Dcorrected = 11.298 + 0.137 + 0.1268
Dcorrected = +11.56 mm
As can be seen from the above example, the corrections for temperature change are small and
can often be ignored.
4.3 Environmental Factors
Since the purpose of the Deformation Meter installation is to monitor site conditions, factors
which may affect these conditions should always be observed and recorded. Seemingly minor
effects may have a real influence on the behavior of the structure being monitored and may give
an early indication of potential problems. Some of these factors include, but are not limited to:
blasting, rainfall, tidal levels, excavation and fill levels and sequences, traffic, temperature and
barometric changes, changes in personnel, nearby construction activities, seasonal changes, etc.