Annex C

(normative)

Field report and GFDT results

The format of reporting the data may be freely chosen whereas the content of Table C.1 is mandatory (see 7.2). An example of plotted data is given in Figure C.1. An example of shear moduli GFDT obtained is given in Table C.2.

Table C.1 — Test data sheet
Commissioner: Order number: Annex:
Object: Date:
Borehole: Mud type: Time:
Test depth: Formation: Soil/Rock:
Device serial No.: Groundwater level
under surface .......... m		 Pocket from .......... m
To .......... m
Measuring direction: Remark: Test operator:
Time
min		 Pressure, pr
MPa		 Displacement, dr1
mm		 Displacement, dr2
mm		 Displacement, dr3
mm		 Mean, dr
mm
           
           
           
           
           
           
           
           
           
           
           
           
           

Data may be plotted according to Figure C.1. Corrected diameter d versus corrected applied pressure p in the three measuring directions is shown on three different graphs and the mean values of d are given on a fourth graph. Then various values of the ground shear modulus GFDT can be calculated for various ranges of pressures during loading and unloading (Table C.2) based on the data plotted on a figure similar to Figure 4.

Plot of test readings in a procedure A test

Key

  • 1—3: plot of test data for each transducer
  • (1 + 2 + 3)/3 : average of the 3 plots
Figure C.1 — Plot of test readings in a procedure A test
Table C.2 — Shear moduli GFDT associated with data plots similar to Figure 4
Load cycle
(No.)		 Range of applied pressure
(MPa)		 Shear moduli GFDT
Displacement transducer No. 1
(MPa)		 Displacement transducer No. 2
(MPa)		 Displacement transducer No. 3
(MPa)		 Mean value
(MPa)
    First loading
1–1 0,50 to 1,00 42 91 96 76
1–2 1,00 to 1,50 72 105 60 79
1–3 1,50 to 2,00 62 82 57 67
1–4 2,00 to 2,50 48 58 48 52
1–5 2,49 to 3,02 48 56 47 50
    Reloading
2–1 0,50 to 1,00 210 220 400 277
2–2 0,50 to 1,50 200 196 196 198
2–3 0,50 to 2,00 164 169 196 176
2–4 0,50 to 2,49 136 142 158 146
    Unloading (30/70)
3–1 1,00 to 0,50 337 255 616 404
3–2 1,50 to 0,50 243 220 251 238
3–3 2,00 to 0,50 192 186 244 208
3–4 2,50 to 0,50 157 159 199 172
3–5 3,02 to 0,50 140 144 172 152

(normative)

Accuracy and uncertainties

D.1 Accuracy of the measuring devices

The accuracy of the measurements depends on the equipment and the type of measuring devices of pressure and displacement included in this equipment. The rules given in 5.4 shall be adhered to.

Because the readings for pressure and displacement are either recorded manually or by transducers, their resolution depends on either the display or the data logger. In both cases, the accuracy depends on how the various devices are calibrated. Therefore, the measuring devices shall be calibrated as close as possible to their measuring range increased by 10 % to 20 %.

D.2 Uncertainties of the measurements

The uncertainties of the measurements depend not only on the equipment. It is defined as the variability of the measurements obtained while measuring any magnitude. The higher the dispersion is, the higher is the uncertainty of the result.

The uncertainty is defined as the interval in which the real measurement of the magnitude is occurring; it is related to the repeatability of the measurements. It shall be calculated according to ENV 13005.

Bibliography

[1] EN 1997-1 Eurocode 7: Geotechnical design — Part 1: General rules

[2] EN 1997-2:2007, Eurocode 7: Geotechnical design — Part 2: Ground investigation and testing

[3] ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in measurement (GUM:1995)

ISO 22476-5:2012 Field testing — Part 5: Flexible dilatometer test