ISO 22476-8:2018 地盤調査とテスト—フィールドテスト—パート8：全変位圧力計テスト | ページ 5

3.1.1

full displacement pressuremeter

FDP

assembly containing a pressuremeter module (3.1.2) and a cone module (3.1.3)

Note 1 to entry: The FDP is jacked or driven directly into undisturbed ground with an integral cone at its lower end thereby creating its own test hole. No preparation of the cavity is permitted either by pre-boring, pre-pushing or any other means.

Note 2 to entry: The applied pressure and associated expansion of the probe are measured and recorded so as to obtain the stress-displacement relationship for the soil as tested (see Figure 1).

Figure 1 — Cross section of a full displacement pressuremeter

Key

1	full displacement pressuremeter	6	membrane
2	pressuremeter module	7	lower fixed membrane point
3	cone module	8	cone
4	push rod connector	9	cone tip
5	upper fixed membrane point	10	25 mm to 50 mm (according to ISO 22476-1)

NOTE The example is not to scale.

3.1.2

pressuremeter module

cylindrical device designed to apply a uniform pressure to the walls of a cavity by means of an expandable flexible single-cell membrane

3.1.3

cone module

cylindrical device with a conical shaped lower end and a connection to which the pressuremeter module (3.1.2) can be attached

Note 1 to entry: The cone module can be instrumented with cone, friction sleeve and pore pressure sensors according to ISO 22476-1.

3.1.4

membrane

part of the pressuremeter module (3.1.2) that is expanded and thereby transmits pressure to the cavity wall

Note 1 to entry: The membrane is fitted on a mandrel. It may be externally or internally reinforced or protected. The reinforcement or protection is deemed to be part of the membrane.

3.1.5

membrane length

l_mb

distance between the upper and lower fixed points of the membrane (3.1.4)

Note 1 to entry: See Figure 1.

3.1.6

pressuremeter system

pressuremeter module (3.1.2) , cone module (3.1.3) , controlling devices and measuring system in combination with any lines connecting them together

3.1.7

volume-displacement type pressuremeter

pressuremeter module (3.1.2) fitted with a sensor to measure the change in the volume of the expanding cavity

3.1.8

radial-displacement type pressuremeter

pressuremeter module (3.1.2) fitted with sensors to measure the change in the radius or diameter of the expanding cavity

3.1.9

membrane pressure loss

pressure in the pressuremeter module (3.1.2) required to expand the membrane (3.1.4) in air, expressed as a funtion of the expansion

3.1.10

membrane compressibility

change in thickness of the membrane (3.1.4) as related to the change in internal pressure in the pressuremeter module (3.1.2)

3.1.11

system compliance

volume change in a pressuremeter system (3.1.6) in response to the internal pressure variation in a situation where the expansion of the membrane (3.1.4) is restricted

Note 1 to entry: The system compliance takes into account both the deformation of the pressuremeter system (3.1.6) and the membrane compressibility (3.1.10) and includes time effects.

3.1.12

applied pressure

pressure applied by the external surface of the membrane (3.1.4) to the walls of the cavity in the soil or weak rock

3.1.13

calibration cylinder

cylindrical tube of known elastic properties used for the restriction of the membrane expansion and hence for the determination of system compliance

3.1.14

reference reading

reading of a sensor just before the membrane (3.1.4) touches the wall of the calibration cylinder (3.1.13) when expanding

3.1.15

cavity volume

V

volume of the cavity in the ground between the upper and lower fixed points of the membrane (3.1.4)

3.1.16

initial cavity volume

V₀

3.1.17

volumetric strain

ε_v

Note 1 to entry: Conversions between the volumetric strain and the radial strain are given in Annex E.

3.1.18

initial cavity radius

r₀

3.1.19

radial strain

ε_r

3.1.20

rate of volumetric strain change

3.1.21

rate of radial strain change

3.1.22

rate of pressure application

3.1.23

thrust machine

equipment that pushes the FDP (3.1.1) and rods (3.1.24) into the ground at a constant rate of penetration

3.1.24

push rods

string of rods for the transfer of forces to the FDP (3.1.1)

Note 1 to entry: The fixed horizontal plane (Figure 2) usually corresponds to the level of the ground surface (on shore or off shore). This may be different from the starting point of the test.

Figure 2 — Penetration length and penetration depth

Key

1	penetration length
2	base of the conical part of the cone module
3	penetration depth
4	fixed horizontal plane

3.1.25

penetration depth

z

depth to the base of the cone, relative to the fixed horizontal plane

3.1.26

penetration length

sum of the length of the push rods (3.1.24) and of the FDP (3.1.1) , reduced by the height of the conical part, relative to the fixed horizontal plane

Note 1 to entry: See Figure 2.

3.1.27

test depth

depth where a pressuremeter test is performed, measured at membrane mid-height and relative to the fixed horizontal plane

3.1.28

measuring system

all sensors, ancillary parts and software used to transfer and to store the measurements made during the full displacement pressuremeter test

3.1.29

unload-reload cycle

controlled decrease in the pressure and volume or radius, after which the expansion is resumed

3.1.30

reload-unload cycle

controlled increase in the pressure and volume or radius during the final contraction phase of the test after which the contraction is resumed

3.1.31

zero load reading

stable output of a measuring system if there is zero load on the sensors, i.e. the parameter to be measured has a value of zero while any auxiliary power supply required to operate the measuring system is switched on

3.1.32

drift

absolute difference of the zero load readings or reference readings of the measuring system before and after the execution of the full displacement pressuremeter test

3.1.33

uncertainty

expanded uncertainty with a coverage factor 2

Note 1 to entry: Coverage factors are defined in ENV 13005.