SIST EN 12715:2021

SLOVENSKI STANDARD
01-januar-2021
Nadomešča:
SIST EN 12715:2002
Izvedba posebnih geotehničnih del - Injektiranje
Execution of special geotechnical work - Grouting
Ausführung von Arbeiten im Spezialtiefbau - Injektionen
Exécution des travaux géotechniques spéciaux - Injection
Ta slovenski standard je istoveten z: EN 12715:2020
ICS:
93.020 Zemeljska dela. Izkopavanja. Earthworks. Excavations.
Gradnja temeljev. Dela pod Foundation construction.
zemljo Underground works
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 12715
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2020
EUROPÄISCHE NORM
ICS 93.020 Supersedes EN 12715:2000
English Version
Execution of special geotechnical work - Grouting
Exécution des travaux géotechniques spéciaux - Ausführung von Arbeiten im Spezialtiefbau -
Injection Injektionen
This European Standard was approved by CEN on 14 September 2020.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 12715:2020 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 7
3 Terms and definitions . 8
4 Information needed for the execution of work . 10
4.1 General. 10
4.2 Specific information . 11
5 Ground investigation . 12
5.1 General. 12
5.2 Specific requirements . 12
5.3 Field grouting trials and field tests . 13
6 Materials and products . 13
6.1 General. 13
6.2 Grout materials . 13
6.2.1 Cement and hydraulic binders . 13
6.2.2 Clay materials . 13
6.2.3 Sands, gravels and fillers . 14
6.2.4 Water . 14
6.2.5 Chemical products and admixtures . 14
6.3 Grouts . 14
6.3.1 General. 14
6.3.2 Suspensions . 15
6.3.3 Solutions . 15
6.3.4 Mortars . 16
7 Execution design . 16
7.1 General. 16
7.2 Execution design basis and objectives . 16
7.3 Grouting principles and methods . 17
7.3.1 Grouting without ground displacement (non-displacement grouting) . 17
7.3.2 Grouting with ground displacement (displacement grouting) . 18
7.4 Grout . 20
7.4.1 Type and composition . 20
7.4.2 General considerations . 20
7.4.3 Parameters and criteria . 21
7.4.4 Applicability . 21
7.5 Grout placement . 21
7.5.1 General. 21
7.5.2 Drilling layout and borehole design . 22
7.5.3 Grouting sequence . 23
7.5.4 Grouting pressure . 23
7.6 Monitoring and control criteria . 23
8 Execution . 24
8.1 General . 24
8.2 Drilling . 24
8.3 Grout preparation . 25
8.3.1 Storage . 25
8.3.2 Batching and mixing . 25
8.3.3 Pumping and delivery . 25
8.4 Grout placement. 26
8.4.1 General . 26
8.4.2 Packers . 27
8.4.3 Special conditions . 27
8.5 Grouting sequences. 27
9 Supervision, testing and monitoring . 28
9.1 General . 28
9.2 Testing . 28
9.3 Monitoring and control . 29
9.3.1 General . 29
9.3.2 Environmental impact . 29
9.3.3 Validation of the grouting works . 29
9.3.4 Monitoring of displacement . 30
9.3.5 Drilling . 30
9.3.6 Grout . 30
10 Records . 30
10.1 General . 30
10.2 Documents produced on site . 31
11 Special requirements (environment, site safety) . 32
11.1 General . 32
11.2 Health and safety . 32
11.3 Environmental protection . 33
Annex A (informative) Glossary . 34
Annex B (informative) Grout types — Processes and their characterizing . 43
Annex C (informative) Measurement of grout parameters . 46
Bibliography . 51

European foreword
This document (EN 12715:2020) has been prepared by Technical Committee CEN/TC 288 “Execution of
special geotechnical works”, the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by May 2021, and conflicting national standards shall be
withdrawn at the latest by month year May 2021.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 12715:2000. The main changes compared to the previous edition are
listed below:
— generally, the text has been checked and brought up to date;
— the Scope now includes Figure 1 to describe the various forms of grouting covered in this document;
— normative references updated and now include reference to EN 1997 for design;
— definitions updated and extended;
— “site investigation” now changed to “ground investigation” in line with EN1997;
— “design considerations” changed to “execution design” in line with EN1997;
— Table 3 moved to Annex B;
— Table 1 included in Clause 8 relating to revised grouting strategies;
— Table B.2 added to characterise grouts;
— Table 5 and A.1 replaced by Annex C with more types of testing included and standards referenced;
— Glossary reviewed and updated;
— Bibliography updated.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
Introduction
The general scope of TC 288 is the standardization of the execution procedures for geotechnical works
(including testing and control methods) and of the required material properties. WG18 has been charged
to revise EN 12715:2000, with the subject area of grouting.
The design, planning and execution of grouting call for experience and knowledge in this specialized field.
The execution phase requires skilled and qualified personnel and the present document cannot replace
the expertise of specialist contractor.
This document has been prepared to complement EN 1997-1, and EN 1997-2.
Until EN 1997-3 is published, the design of grouting works is not clearly defined. In particular, the
boundary between design under the proposed EN 1997-3 and design as part of the execution of grouting
works has not been determined. This document has therefore adopted a distinction between execution
design, i.e. the design of grouting methodology and the other phases of design.
Clause 7 “Execution Design” of this document expands on design only where necessary for the execution.
This document provides coverage of the construction and supervision requirements for grouting works.

Under preparation. Stage at the time of publication: prEN 1997-3.
1 Scope
This document is applicable to the execution, testing and monitoring of geotechnical grouting work.
Grouting for geotechnical purposes (geotechnical grouting) is a process in which the remote placement
of a pumpable material in the ground is indirectly controlled by adjusting its rheological characteristics
and by the manipulation of the placement parameters (pressure, volume and the flow rate).
The following principles and methods of geotechnical grouting are covered by this document:
— displacement grouting (compaction and compensation grouting);
— grouting without displacement of the host material (permeation, fissure/contact grouting, bulk
filling).
Figure 1 illustrates the various injection methods associated with these two principles.

NOTE The term consolidation grouting is sometimes used to emphasize an improvement in the strength or
deformation characteristics of a soil or rock mass, with the aim that it does not undergo any unacceptable
deformation. The term compensation grouting is used when the objective of grouting is to concurrently compensate
for ground loss.
Figure 1 — Grouting principles and methods
The principal objectives of geotechnical grouting are:
— the modification of the hydraulic/hydrogeological characteristics of the ground;
— the modification of the mechanical properties of the ground;
— the filling of natural cavities, mine workings, voids adjacent to structures;
— inducing displacement to compensate for ground loss or to stabilize and lift footings, slabs and
pavements.
Specialized grouting activities, generally associated with structural and/or emergency works, are not
covered by this document.
The execution, testing and monitoring of jet grouting work is not covered by this document and is covered
by EN 12716.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 197-1, Cement - Part 1: Composition, specifications and conformity criteria for common cements
EN 197-2, Cement - Part 2: Assessment and verification of constancy of performance
EN 480-1, Admixtures for concrete, mortar and grout - Test methods - Part 1: Reference concrete and
reference mortar for testing
EN 480-2, Admixtures for concrete, mortar and grout - Test methods - Part 2: Determination of setting time
EN 480-4, Admixtures for concrete, mortar and grout - Test methods - Part 4: Determination of bleeding of
concrete
EN 480-5, Admixtures for concrete, mortar and grout - Test methods - Part 5: Determination of capillary
absorption
EN 480-6, Admixtures for concrete, mortar and grout - Test methods - Part 6: Infrared analysis
EN 480-8, Admixtures for concrete, mortar and grout - Test methods - Part 8: Determination of the
conventional dry material content
EN 480-10, Admixtures for concrete, mortar and grout - Test methods - Part 10: Determination of water
soluble chloride content
EN 480-11, Admixtures for concrete, mortar and grout - Test methods - Part 11: Determination of air void
characteristics in hardened concrete
EN 480-12, Admixtures for concrete, mortar and grout - Test methods - Part 12: Determination of the alkali
content of admixtures
EN 934-1, Admixtures for concrete, mortar and grout - Part 1: Common requirements
EN 934-3, Admixtures for concrete, mortar and grout - Part 3: Admixtures for masonry mortar - Definitions,
requirements, conformity and marking and labelling
EN 934-4, Admixtures for concrete, mortar and grout - Part 4: Admixtures for grout for prestressing tendons
- Definitions, requirements, conformity, marking and labelling
EN 934-6, Admixtures for concrete, mortar and grout - Part 6: Sampling, assessment and verification of the
constancy of performance
EN 1997-1, Eurocode 7: Geotechnical design - Part 1: General rules
EN 1997-2, Eurocode 7 - Geotechnical design - Part 2: Ground investigation and testing
EN 16228-6, Drilling and foundation equipment - Safety - Part 6: Jetting, grouting and injection equipment
EN ISO 22282 (series), Geotechnical investigation and testing - Geohydraulic testing (ISO 22282 series)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
NOTE 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 A.
3.1
bulk filling
placement of grout to fill subterranean cavities
3.2
compaction grouting
injection of a low slump mortar or comparatively stiff (viscous and cohesive) particulate grout into the
soil to compact/densify it by expansion alone
Note 1 to entry: Expanding grouts can be used to cause compaction but may also permeate the ground.
3.3
contact grouting
injection of grout into the interface between man-made structures and the ground
3.4
displacement grouting
injection of grout into a host medium in such a manner as to deform, compress, or displace the ground
3.5
effective pressure
pressure governing the flow in the ground, estimated from the grouting pressure considering the sum of
all head losses and head gains in the injection system and the ground
3.6
fissure grouting
injection of grout into fissures, joints, fractures and discontinuities in rock
3.7
grout
pumpable material (suspension, solution or resins, emulsion or mortar), introduced into soil or rock,
which stiffens and sets with time
3.8
grouting pressure
working pressure
pressure applied during the grouting process and measured at defined locations, usually at the pump or
the borehole collar
3.9
hydraulic fracturing
injection of water or grout that creates a new localized fracture in the ground
3.10
hydraulic jacking
hydrojacking
injection of water or grout within existing fractures in the ground to enhance the grout spread and
penetrability
3.11
penetration grouting
grout injection of joints or fractures in rock, or pore spaces in soil, without displacing the ground
Note 1 to entry: The term includes permeation (impregnation), fissure and contact grouting.
3.12
permeation grouting
impregnation grouting
replacement of interstitial water or gas of a porous medium with a grout
3.13
non-displacement grouting
injection of grout into a host medium in such a manner as not to deform, compress, or displace the ground
Note 1 to entry: The term includes penetration grouting and bulk filling.
3.14
bleed
process by which water forms a separate segregation phase from the grout under gravity or pressure
3.15
stable suspension
ability of a suspension to minimise bleed and segregation and retain its original properties under
pressure
3.16
field grouting trial
trial executed in order to define or validate a grouting methodology
3.17
hydraulic binder
all cements and similar products used in aqueous suspensions to produce grout
3.18
fine
hydraulic binders or cements that are characterized by a particle size d of less than 40 µm
3.19
microfine
hydraulic binders or cements that are characterized by a particle size d of less than 20 µm
3.20
ultrafine
hydraulic binders or cements that are characterized by a particle size d of less than 10 µm
3.21
additive
any grout ingredient other than the basic components of a grout mix (water,
aggregates, or cementitious material), which is used to modify the properties of the fluid and the
hardened grout
3.22
mortars
highly particulate grout containing sand and fine aggregates, commonly a concrete with an aggregate size
of less than 4 mm
3.23
split spacing
procedure by which additional grout injection holes are located midway between previously grouted
holes
3.24
sleeved pipe
TAM
injection pipe perforated at regular intervals where the perforations are covered externally by sleeves
acting as non-return valves
Note 1 to entry: TAM is the abbreviation for tube á manchette.
4 Information needed for the execution of work
4.1 General
4.1.1 All information required to execute the works shall be provided in advance.
4.1.2 This information should include the following, where relevant:
— any legal or statutory restrictions;
— the location of main grid lines for setting out;
— the conditions of structures, roads, services, etc. adjacent to the work, including any necessary
surveys;
— a suitable quality management system, including supervision, monitoring and testing;
— the geometry of the site (boundary conditions, topography, access, slopes, headroom restrictions,
etc.);
— the existing underground structures, services, known contaminations, and archaeological
constraints;
— the environmental restrictions, including noise, vibration, pollution; and
— the future or ongoing activities such as dewatering, tunnelling, deep excavations on or adjacent to
the worksite.
4.2 Specific information
4.2.1 The specific information shall cover, where relevant:
— execution specifications;
— previous use of the site;
— adjacent foundations (types, loads and geometry);
— geotechnical information and data as specified in Clause 5;
— presence of obstructions in the ground (old masonry, anchors, concrete, blocks and boulders, etc.);
— presence of headroom restrictions;
— presence of archaeological remains;
— presence of natural and/or manmade cavities (mines, etc.);
— presence of polluted ground and type, extent and degree of pollution;
— any specific requirements for the grouting works, in particular those pertaining to tolerances, quality
of materials, methods and frequency of testing;
— where available, previous experience with grouting works on or adjacent to the site;
— proposed adjacent enabling or advance works that could affect the grouting works;
— functional requirements for instrumentation and monitoring of potentially affected structures;
— necessity, extent, procedure and content for any survey on the conditions of structures, roads,
services, etc. adjacent to the works area.
4.2.2 Required site surveys shall be carried out and be available prior to the commencement of the
works.
NOTE The results are useful to define the threshold values for any movement which affect adjacent structures
by the works area construction.
4.2.3 Any additional or deviating requirements to this document shall be established and agreed with
the relevant parties or authorities before the commencement of the works and the quality control system
shall be suitably amended.
5 Ground investigation
5.1 General
Any ground investigation shall fulfil the requirements of EN 1997-2 and the relevant national documents.
5.2 Specific requirements
5.2.1 Relevant experience of the execution of comparable grouting works under similar conditions
and/or in the vicinity of the site should be taken into account when determining the extent of the ground
investigation (reference to relevant experience is permitted if appropriate means of verification were
taken).
5.2.2 The ground investigation report shall be sufficient for the execution of the grouting works.
5.2.3 If during grouting the ground conditions differ from those in the ground investigation report this
shall be reported.
5.2.4 For the execution of grouting works, the ground investigation report should contain the following
specific information:
— the relevant physical and chemical characteristics of the ground and groundwater;
— the presence of any anisotropies or permeable horizons which could influence the grouting works;
— the orientation, frequency, and aperture of rock joints and the composition and nature of any infill
material;
— the location and nature of filled or open cavities;
— the presence of obstructions that require special drilling and grouting methods or equipment;
— the presence and characteristics of ground that is likely to loosen, soften or become unstable,
dissolve, collapse or swell as a result of drilling or grouting;
— the presence of strata with high groundwater velocities and/or permeabilities.
5.2.5 Where relevant, the following specific drilling information should be recorded:
— location and cause of core losses;
— unstable zones and stabilization measures taken;
— water level at the beginning and end of a run, zones of water loss and gain, measurements of return
water, water colour and changes in colour;
— recording of drill parameters in the case of destructive boreholes;
— rate of advance.
5.2.6 Permeability testing shall be done in accordance with EN ISO 22282 series.
5.3 Field grouting trials and field tests
5.3.1 Field grouting trials should be executed where ground investigations and local or comparable
experience is insufficient to support or justify the effectiveness of the grouting project.
NOTE Some indication of in situ groutability can be obtained by permeating reconstituted soil samples with
trial grouts, under laboratory conditions.
5.3.2 The trials should provide information on borehole spacing, grout type, procedure and
parameters.
5.3.3 Detailed records shall be kept of each operation performed during the grouting trials.
6 Materials and products
6.1 General
6.1.1 All grout components and grouts shall comply with the specifications for the works.
6.1.2 The suitability of the grout constituents and their combination with the ground shall be
considered and investigated if necessary.
6.1.3 Once established, the sources of grout materials shall not be changed without prior compliance
verification or testing.
6.2 Grout materials
6.2.1 Cement and hydraulic binders
6.2.1.1 Cements shall comply with EN 197-1 and EN 197-2. Cements that do not comply with
EN 197-1 may be used if considered acceptable for the grouting purpose envisaged.
6.2.1.2 Testing of cements and other binders shall be in accordance with their appropriate standard.
6.2.1.3 When selecting the type of hydraulic binder for grout, its grain size distribution shall be
evaluated in relation to the dimensions of the rock apertures or interstitial voids of the ground to be
treated.
6.2.1.4 Pozzolans, blast furnace slag, silica fume and fly ash from thermal power plants or any other
reactive material may be used in grouts.
6.2.2 Clay materials
6.2.2.1 Natural clays, activated or modified bentonites can be added to cement-based grouts in order
to reduce bleeding and/or filtration under pressure, to vary the viscosity and cohesion (yield) of the
grout, or to improve the pumpability and/or penetrability of the grout.
6.2.2.2 The mineralogy, particle size, water content, and Atterberg limits of the clay should be known.
6.2.2.3 The effect of the clay materials on the grout properties should be evaluated if it has not been
established by comparable experience.
6.2.3 Sands, gravels and fillers
6.2.3.1 Sands, gravels and inert fillers may be added to cement grouts or clay suspensions as bulking
agents or as a means of varying the consistency of the grout, its resistance to wash-out, or its mechanical
strength and deformability.
6.2.3.2 The grain size distribution of sands, gravels and fillers shall be known.
6.2.4 Water
6.2.4.1 Unless potable water is used for grouting, its chemical suitability shall be verified.
6.2.4.2 Sea water or saline groundwater can be used provided that the properties of the grout mix
are not impaired.
6.2.5 Chemical products and admixtures
6.2.5.1 The effects of all chemical products and their by-products, including the effect of time,
resulting from the reaction of the chemical products with other components of the grout or with the
surrounding ground shall be considered.
6.2.5.2 Admixtures may be added to the grout to modify its properties and to control its parameters
such as viscosity, setting time, stability, strength, resistance, cohesion and permeability after placement.
6.2.5.3 Admixtures to grout such as superplasticizers, water retaining agents, air entrainers and
others shall be subject to EN 934-1, EN 934-3, EN 934-4, EN 934-6 and EN 480-1, EN 480-2, EN 480-4,
EN 480-5, EN 480-6, EN 480-8, EN 480-10, EN 480-11, and EN 480-12.
6.3 Grouts
6.3.1 General
6.3.1.1 Grouts are classified as:
— suspensions: either particulate or colloidal (nano-particles);
— solutions: either true or colloidal (large molecules);
— mortars.
6.3.1.2 The following intrinsic properties shall be considered when choosing a grout:
— rheology (viscosity, cohesion, etc.), setting time, stability;
— particle size, if applicable;
— strength and durability; and
— toxicity and environmental impact.
6.3.2 Suspensions
6.3.2.1 Suspensions are characterized by the following properties:
— water/solid and/or binder ratio;
— grain size distribution;
— rate of segregation and bleeding;
— stability under pressure filtration;
— rheology and its evolution with time.
6.3.2.2 The tendency of suspended solids to flocculate shall be taken into account, particularly when
using fine, microfine or ultrafine cements.
6.3.2.3 The tendency of solids in suspension to settle in water due to gravity forces, and the tendency
of the suspensions to bleed under pressure, shall be considered in relation with the nature and properties
of the host medium.
6.3.2.4 Clay suspensions should be prepared so that the clay particles are deflocculated and hydrated
before injecting.
6.3.3 Solutions
6.3.3.1 After setting, some types of grouts are not stable with time and their use should be assessed.
6.3.3.2 The effect of syneresis on the properties of the treated ground and on the environment,
particularly their long-term effect, shall be evaluated prior to treatment.
6.3.3.3 The effect of temperature on the grout behaviour during production and placement shall be
taken into account.
6.3.3.4 Special attention shall be paid to:
— the toxicity of individual grout components;
— the risk of dilution of the grout mixture in the groundwater leading to prolongation of the setting
time;
— inhibition of the chemical reaction;
— the toxicity and environmental impact of any substance released into the groundwater if the chemical
reaction is not fully achieved or modified by the host medium.
6.3.4 Mortars
6.3.4.1 Mortars flowing under their own weight can be used for filling cavities, large cracks, open
fissures and voids in the ground.
6.3.4.2 When used for compaction grouting, the mortar should:
— contain a minimum of 15 % of fines passing 0,1 mm;
— have high internal friction;
— have a slump of 9cm ± 3cm tested according to EN 12350-2;
— remain pumpable for grouting.
7 Execution design
7.1 General
7.1.1 The basic standard for the design of ground improvement is EN 1997-1.
7.1.2 This present standard only covers the execution design e.g. grout materials, pressures, flow rates,
sequence, spacing, etc. for the planning and implementation of geotechnical grouting applications.
7.2 Execution design basis and objectives
7.2.1 The execution design and planning of a grouting application shall consider the objectives, impact
of varying ground conditions or variations in the behaviour of the host materials.
7.2.2 The execution design might need to be adapted as the work progresses.
7.2.3 To formulate a grouting execution design, the following information shall be made available:
— a definition of the grouting objectives, its required performance and the control criteria as set out in
the detailed design;
— relevant ground information, in particular geological, geotechnical and hydrogeological data
(including water chemistry) (see Clause 5);
— limitations imposed by environmental restrictions, allowable deformations and displacements, the
influence of or on adjoining structures (buildings and foundations, etc.) or any other parameters
which could affect the choice of grout mix and placement technique;
— references to other grouting projects executed in the same area or under comparable circumstances,
if available.
7.2.4 Based on the ground investigation, the grouting trials and the detailed design, the following
aspects shall be considered and addressed by the execution design:
— the geometry and extent of the ground to be treated;
— the measurable properties required to be achieved by the detailed design;
— the drilling method, layout and sequence;
— the grouting techniques and methods to be applied;
— the spacing of injection points;
— the sequencing of the injections with respect to time, grout composition and injection point;
— the grouting values and any specified limits (injection pressure, flowrate and quantity of grout to be
injected and time);
— the composition and characteristic of grouts to be used;
— the required tests and field controls to be adopted before, during and after grouting;
— the required instrumentation for monitoring, control and data logging.
7.2.5 The following aspects should be considered for grouting:
— the required grout properties;
— potential changes of the in situ state of stress and pore pressures as a result of the grouting work, the
existing groundwater conditions as well as expected post construction conditions;
— the toxicity of the grouting products;
— the working environment in which the grouting materials shall be stored, mixed and injected;
— the availability and reliable supply of grouting materials;
— environmental and safety restrictions;
7.2.6 The time period between the completion of a phase of grouting and the start of the follow-on
works shall be specified.
7.3 Grouting principles and methods
7.3.1 Grouting without ground displacement (non-displacement grouting)
7.3.1.1 General Considerations
To avoid displacement grouting shall be carried out at controlled pressures and flow rates, using
appropriate grouts.
7.3.1.2 Penetration grouting
7.3.1.2.1 Penetration grouting comprises permeation, fissure and contact grouting.
7.3.1.2.2 The function of penetration grouting is to reduce the permeability of the soil or rock and/or
increase the strength and density.
7.3.1.2.3 The flow (injection) rate Q shall be controlled to ensure that the effective pressure remains
lower than the ground fracturing pressure.
7.3.1.2.4 Grouting with microfine, ultrafine or chemical grouts in the presence of coarse grained soils
could require preliminary grouting e.g. with cement based grouts.
7.3.1.2.5 The function of fissure or contact grouting of rock is the filling of cavities, open fissures,
fractures or joints in a rock mass with grout without creating new fractures or displacement, in order to
reduce the permeability and/or increase the strength of the grouted mass.
7.3.1.2.6 The frequency, orientation, extent, aperture, roughness and infilling of the discontinuities of
the rock shall be considered in order to formulate the design and the borehole arrangement.
7.3.1.2.7 The drilling method shall be governed by the requirements set out in the execution design
and/or specifications.
7.3.1.2.8 For pre- and post- tunnel excavation grouting the applied pressures and materials shall be
chosen based on the geometrical and ground conditions.
NOTE 1 Pre-grouting is typically done to reduce groundwater inflows into the tunnel to allow the excavation to
proceed and/or to achieve the inflow performance requirements.
NOTE 2 Post-grouting is done to attain the performance requirements or further reduce local inflows.
7.3.1.2.9 The design of any rock grouting shall take into account the presence or extent of any
excavation damage zone.
7.3.1.3 Bulk filling
7.3.1.3.1 Bulk filling is generally applied to the placement of large volumes of grout under gravity or at
low pressures.
7.3.1.3.2 If a large volume of cementitious grout is placed in an enclosed space, the effect of high local
temperatures and induced stresses shall be taken into account.
7.3.1.3.3 Bulk filling may be followed by a phase of grouting under pressure to fill the remaining voids.
7.3.2 Grouting with ground displacement (displacement grouting)
7.3.2.1 General considerations
7.3.2.1.1 The function of displacement grouting is the injection of grout under pressure with the
deliberate intent of spatially displacing the ground.
7.3.2.1.2 Displacement grouting can be employed to produce controlled movements, to reduce
permeability, to reinforce or stabilize the ground and/or to increase the stiffness under a structure or
foundation.
7.3.2.2 Hydraulic fracture grouting
The function of hydraulic fracture grouting is the creation of fractures within soil or rock in order to
create additional total volume thereby mitigating or producing controlled movements, e.g. uplift of
structures.
7.3.2.3 Hydraulic jacking grouting
7.3.2.3.1 The function of hydraulic jacking grouting of rock masses is to enhance the grout spread and
penetrability.
7.3.2.3.2 The propagation of hydraulic fractures should be controlled to reduce the risk of
unacceptable displacement.
NOTE This is usually done by applying an incremental series of limited volume injections over a period of time.
7.3.2.4 Compensation grouting
7.3.2.4.1 The function of compensation grouting is to inject grout into the ground that is undergoing
volume loss either due to the result of engineering works such as deep excavations or tunnelling or
consolidation of compressible material such that the volume loss is reversed or reduced.
7.3
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