3 Terms, definitions and symbols

3.1 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

3.1.1

pressuremeter

whole equipment which is used to carry out a Ménard pressuremeter test, excluding the means necessary to place the pressuremeter probe into the ground

NOTE 1 A pressuremeter includes a pressuremeter probe, a pressure and volume control unit, called CU, lines to connect the probe to the CU and, in the case of procedure B, a data logger which is either built into the CU or linked to it.

NOTE 2 See Figure 2.

3.1.2

pressuremeter test pocket

circular cylindrical cavity formed in the ground to receive a pressuremeter probe

3.1.3

pressuremeter borehole

borehole in which pressuremeter pockets with circular cross sections are made in the ground, and into which the pressuremeter probe is to be placed

3.1.4 pressuremeter test

process during which a pressuremeter probe is inflated in the ground and the resulting pocket expansion is measured by volume as a function of time and pressure increments according to a defined programme

NOTE See Figure 4 and F.1.

3.1.5

pressuremeter sounding

whole series of sequential operations necessary to perform Ménard pressuremeter testing at a given location, i.e. forming pressuremeter test pockets and performing pressuremeter tests in them

NOTE See F.2.

3.1.6

pressuremeter pressure reading, p_r

pressure p_r as read at the CU elevation in the liquid circuit supplying the central measuring cell

3.1.7

pressure loss

difference between the pressure inside the probe and the pressure applied to the pocket wall

3.1.8

volume loss

difference between the volume actually injected into the probe and the volume read on the measuring device

3.1.9

raw pressuremeter curve

graphical plot of the injected volumes recorded at time 60 s, V₆₀, versus the applied pressure at each pressure hold, p_r

3.1.10

corrected pressuremeter curve

graphical plot of the corrected volume V versus the corrected pressure p

NOTE See Figure 5.

3.1.11

Ménard creep

difference in volumes recorded at 60 s and at 30 s at each pressure hold: V₆₀ – V₃₀ = ΔV_60/30

3.1.12

corrected Ménard creep curve

graphical plot of the corrected Ménard creep versus the corrected applied pressure at each pressure hold

NOTE See Figure 5.

3.1.13

pressuremeter log

graphical report of the results of the pressuremeter tests performed in pockets at a succession of depths in the same pressuremeter borehole, together with all the information gathered during the drilling

NOTE See Annex F.

3.1.14

Ménard pressuremeter modulus, E_m

E-modulus obtained from the section between (p₁, V₁) and (p₂, V₂) of the pressuremeter curve

NOTE See Figure 5 and Annex D.

3.1.15

Ménard pressuremeter limit pressure, p_lm

pressure at which the volume of the test pocket at the depth of the measuring cell has doubled its original volume

NOTE See Annex D.

3.1.16

pressuremeter creep pressure, p_LM

pressure derived from the creep curve

NOTE See Annex D.

3.1.17

operator

qualified person who carries out the test

3.1.18

casing

lengths of tubing inserted into a borehole to prevent the hole caving in or to prevent the loss of flushing medium to the surrounding formation, above pocket location

3.2 Symbols

For the purposes of this document, the symbols given in Table 1 apply.

Symbol	Description	Unit
a	Apparatus volume loss coefficient	cm3/MPa
dci	Outside diameter of the inner part of the probe with slotted tube	mm
di	Inside diameter of the calibration cylinder used for the volume loss calibration	mm
dc	Outside diameter of the central measuring cell, including any additional protection such as a slotted tube	mm
dt	Drilling tool diameter	mm
e	Wall thickness of the calibration cylinder used for the volume loss calibration	mm
lp	Length of the calibration cylinder used for the volume loss calibration	mm
lg	Length of each guard cell	mm
lgs	Length of each guard cell for a short central measuring cell pressuremeter probe	mm
lgl	Length of each guard cell for a long central measuring cell pressuremeter probe	mm
lm	Length along the tube axis of the slotted section of the slotted tube	mm
lc	Length of the central measuring cell of the probe, measured after fitting the membrane	mm
lcs	Length of the short central measuring cell after fitting the membrane	mm
lcl	Length of the long central measuring cell after fitting the membrane	mm
mE	Minimum value, strictly positive, of the mi slopes	cm3/MPa
mi	Slope of the corrected pressuremeter curve between the two points with coordinates (pi-1, Vi-1) and (pi, Vi).	cm3/MPa
p	Pressure applied by the probe to the ground after correction	MPa
pe	Correction for membrane stiffness usually called pressure loss of the probe	MPa
pe	Pressure at the origin of the segment exhibiting the slope mE	MPa
pel	Ultimate pressure loss of the probe	MPa
pfM	Pressuremeter creep pressure	MPa
pg	Gas pressure applied by the control unit indicator to the guard cells of the pressuremeter probe	MPa
ph	Hydrostatic pressure between the control unit indicator and the central measuring cell of the pressuremeter probe	MPa
pk	Gas pressure in the guard cells	MPa
pLM	Ménard pressuremeter limit pressure of the ground	MPa
pLM *	Ménard net pressuremeter limit pressure of the ground	MPa
pLMH	Ménard pressuremeter limit pressure as extrapolated by the hyperbolic best fit method	MPa
pLMDH	Ménard pressuremeter limit pressure as extrapolated by the double hyperbolic method	MPa
pLMR	Ménard pressuremeter limit pressure as extrapolated by the reciprocal curve method	MPa
pm	Pressure loss of the central measuring cell membrane for a specific expansion	MPa
pr	Pressure reading at the CU transducer elevation in the central measuring cell liquid circuit	MPa
pc	Liquid pressure in the central measuring cell of the pressuremeter probe	MPa
pt	Target pressure for each pressure hold according to loading programme	MPa
p1	Corrected pressure at the origin of the pressuremeter modulus pressure range	MPa
p2	Corrected pressure at the end of the pressuremeter modulus pressure range	MPa
t	Time	s
ti	Time required for incrementing to the next pressure hold	s
th	Time the loading pressure level is held	s
us	Pore water pressure in the ground at the depth of the test	MPa
z	Elevation, positively counted above datum	m
zc	Elevation of the pressure measuring device for the liquid injected in the measuring cell	m
zcg	Elevation of the pressure measuring device for the gas injected in the guard cells of the pressuremeter probe	m
zN	Elevation of the ground surface at the location of the pressuremeter sounding	m
zp	Elevation of the measuring cell centre during testing	m
zw	Elevation of the ground water table (or free water surface in a marine or river environment)	m
CU	Pressure and volume control unit	—
E	Type of pressuremeter probe where the three cells are formed by three separate membranes in line	—
EM	Ménard pressuremeter modulus	MPa
G	Type of pressuremeter probe where the central measuring cell is formed by a dedicated membrane over which an external membrane is fitted to form the guard cells (see Figure 2)	—
Ko	Coefficient of earth pressure at rest at the test depth	—
V	Value, after zeroing and data correction, of the volume injected in the central measuring cell and measured 60 s after starting a pressure hold	cm3
Vc	Original volume of the central measuring cell, including the slotted tube, if applicable	cm3
Vm	The average corrected volume between V1 and V2	cm3
Vp	Volume obtained in the volume loss calibration test (see Figure B.2)	cm3
Ve	Value, after data correction, of the volume injected in the central measuring cell for pressure pe	cm3
Vl	Value, after data correction, of the volume injected in the central measuring cell when the original volume of the pressuremeter cavity has doubled	cm3
Vr	Volume injected in the probe as read on the CU, before data correction	cm3
Vt	Volume of the central measuring cell possibly including the slotted tube	cm3
V1	Corrected volume at the origin of the pressuremeter modulus pressure range (see Figure 5)	cm3
V2	Corrected volume at the end of the pressuremeter modulus pressure range	cm3
V30	Volume injected in the central measuring cell as read 30 s after the beginning of the pressure hold	cm3
V60	Volume injected in the central measuring cell as read 60 s after the beginning of the pressure hold	cm3
β	Coefficient used to determine the pressuremeter modulus pressure range	—
γ	Unit weight of soil at the time of testing	KN/m3
γI	Unit weight of the liquid injected in the central measuring cell	KN/m3
γw	Unit weight of water	KN/m3
λ	Rate of change of pressure head of gas at pk per metre depth	m-1
v	Poisson's ratio	—
σvs	Total vertical stress in the ground at test depth	kPa
σhs	Total horizontal stress in the ground at test elevation	kPa
Δp	Loading pressure increment	MPa
Δp1	Initial pressure increment	MPa
ΔV60/30	Injected volume change from 30 s to 60 s after reaching the pressure hold – the Ménard creep	cm3
ΔV60/60	60 s injected volume change between successive pressure holds	cm3