3 Definitions and symbols
3.1 Definitions
The definitions given in this chapter cover only the most important terms involved in geotechnical grouting. Further definitions are given in the glossary in annex B.
3.1.1
bulk filling
fr: injection de comblement
de: Hohlraumverfüllung
bulk filling is the placement of grout with a high particulate content to fill substantial voids
3.1.2
compaction grouting
fr: injection solide
de: Verdichtungsinjektion (Kompaktionsinjektion)
displacement grouting method which aims at forcing a mortar of high internal friction into the soil to compact it without fracturing it
3.1.3
contact grouting
fr: injection de contact
de: Kontaktinjektion
injection of grout into the interface between man-made structures and the ground
3.1.4
displacement grouting
fr: injection avec déplacement des terrains
de: Verdrängungsinjektion
injection of grout into a host medium in such a manner as to deform, compress, or displace the ground
3.1.5
effective pressure
fr: pression effective
de: wirksamer Druck
actual grout pressure acting in the ground
3.1.6
fissure grouting
fr: injection de fissure
de: Kluftinjektion
injection of grout into fissures, joints, fractures and discontinuities, particularly in rock
3.1.7
gravity grouting
fr: injection gravitaire
de: drucklose Verfüllung
grouting under no applied pressure other than the height of grout fluid. Sometimes referred to as tremie grouting
3.1.8
grout
fr: coulis
de: Injektionsgut
pumpable material (suspension, solution, emulsion or mortar), injected into soil or rock, which stiffens and sets with time
3.1.9
grouting pressure
fr: pression d'injection
de: Injektionsdruck
pressure applied during the grouting process and measured at defined locations (usually at the pump or the borehole collar)
3.1.10
hydraulic fracturing (hydraulic fracture, claquage grouting)
fr: fracturation hydraulique (injection de claquage)
de: Hydraulische Rissbildung (Claquage)
fracturing of a ground initiated by the injection of water or grout under a pressure in excess of the local tensile strength and confining pressure; also called hydrofracturing, hydrosplitting, hydrojacking or claquage
3.1.11
penetration grouting
fr: injection de pénétration
de: Eindringinjektion
grout injection of joints or fractures in rock, or pore spaces in soil, without displacing the ground. The term includes permeation (impregnation), fissure and contact grouting
3.1.12
permeation (impregnation) grouting
fr: injection d'imprégnation
de: Poreninjektion (Imprägntion durch Porenverfüllung)
replacement of interstitial water or gas of a porous medium with a grout at injection pressures low enough to prevent displacement
3.1.13
non-displacement grouting
fr: injection sans déplacement des terrains
de: Verdrängungsfreie Injektion (Injektion ohne Baugrundverdrängung)
substitution of the natural interstitial fluid in the accessible existing voids of the ground by a grout or mortar without any significant displacement of the ground. The term includes penetration grouting and bulk filling
3.1.14
stable suspension
fr: suspension stable
de: stabile Suspension
stable suspensions exhibit in 2 hours less than 5 per cent bleeding of clear water at the top of a 1 000 ml cylinder with an internal diameter of 60 mm at a temperature of 20 °C
3.2 Symbols and units
The following symbols and units are used in this standard.
Symbols | Denomination | Unit |
T | Temperature | [°C] |
V | Volume injected | [m3] |
P | Injection pressure | [Pa] |
Q | Injection or flow rate | [m3/s] or [l/s] |
k | Intrinsic (absolute) permeability1) | [m2] |
K | Coefficient of hydraulic conductivity | [m/s] |
i | Hydraulic gradient | [dimensionless] |
d10, d15 D85, D90 |
Largest particle size of the smallest 10, 15 % of grout Largest grain size of the smallest 85, 90 % of the medium |
[mm] |
t | Setting time | [s] |
σc τf |
Compressive strength Shear strength |
[Pa] |
σ τ |
Normal stress Shear stress |
[Pa] |
ε | Strain | [dimensionless] |
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Shear rate | [s–1] |
µapp η ν |
Viscosity (apparent) (dynamic) (kinematic) |
[Pa·s], [kg/m·s] [Pa·s] [m2/s] |
C | Cohesion | [Pa] |
τ0 | Yield shear stress | [Pa] |
ρ | Density | [kg/m3] |
γ | Specific or unit weight | [kN/m3] |
tM | Outflow time (Marsh) | [s] |
R | Action radius | [m] |
1 Pa = 1 N/m2 = 10–5 bar 1) It is common practice in geotechnical engineering to use k for hydraulic conductivity. Nevertheless, this refers to the parameters generally used in rock and fluid mechanics. |
4 Information needed
4.1 All information relevant to the execution of the grouting works should be provided with the work specifications.
4.2 The following technical information shall be available on site before the commencement of the works:
- site conditions and limitations, e.g. size, gradients, access;
- working restrictions, including any environmental, legal or statutory restrictions;
- any underground contamination or hazard which could affect the method of execution or the safety of the working environment;
- design and specifications for the works.
4.3 The following technical information should be available on site before the commencement of the works:
- geological and geotechnical conditions (see chapter 5);
- the co-ordinate locations of the site with respect to the national grid;
- existence, location and conditions of any adjacent structures, e.g. buildings, roads, utilities or services, underground structures and their foundations;
- any concurrent or subsequent activities which could affect the works (e.g. groundwater extraction or recharge, tunnelling, other deep excavations);
- any previous experience with grouting or other underground works on or adjacent to the site, or relevant experience in the execution of comparable works under similar conditions;
- any information relevant for the production of drawings and method statements (where required);
- any additional requirements for the supervision, monitoring or testing of the works.
4.4 The following aspects shall be established before the commencement of the works and shall be available in written form on site:
- the requirement, and assignment, for any survey of the condition of adjacent structures, roads, services, etc. to be carried out prior to, during and after the works;
- specific procedures and criteria for the verification, control and acceptance of the grouting works;
- the clear division of tasks with respect to the design, execution, interpretation of results and approval of the works.