SIST EN 12716:2002
(Main)Execution of special geotechnical works - Jet grouting
Execution of special geotechnical works - Jet grouting
1.1 ST This Standard is applicable to the execution, testing and monitoring of jet-grouting works. Some considerations about design are also given. 1.2 ST The execution of jet-grouting works requires knowledge and experience in this type of contruction. NOTE 1: The jet-grouting process must be distinguished from the grouting processes covered by the standard EN 00288006.
Ausführung von besonderen geotechnischen Arbeiten (Spezialtiefbau) - Düsenstrahlverfahren (Hochdruckinjektion, Hochdruckbodenvermörtelung, Jetting)
Anwendungsbereich
Diese Norm gilt für Ausführung, Prüfung und Überwachung von Düsenstrahlarbeiten. Aspekte der Planung, die sich speziell auf das Düsenstrahlverfahren beziehen, sind in Abschnitt 7 enthalten. Weitere allgemeine Erfordernisse für den Entwurf befinden sich im Anhang A und können in die Norm einbezogen werden oder in Abschnitte einer späteren Fassung des Eurocode 7 aufgenommen werden.
ANMERKUNG Das Düsenstrahlverfahren unterscheidet sich wesentlich von den in EN 12715 erfassten Injektionsverfahren.
Exécution des travaux géotechniques spéciaux - Colonnes, panneaux et structures de sol-ciment réalisés par jet
Domaine d'application
La présente norme s'applique a la réalisation par jet de colonnes, de panneaux et de structures enterrés constitués d'un mélange de sol et de ciment ainsi qu'aux essais et au contrôle de ces travaux. Des prescriptions plus générales qui pourraient etre incluses dans ce document ou faire l'objet d'articles dans les futures éditions de l'Eurocode 7 sont listées en annexe A.
NOTE Il convient de faire la distinction entre les procédés d'exécution des colonnes, des panneaux et des structures de sol-ciment réalisés par jet, et les procédés d'injection couverts par l'EN 12715.
Izvedba posebnih geotehničnih del - Injektiranje pod visokimi pritiski
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Execution of special geotechnical works - Jet groutingWLVNLExécution des travaux géotechniques spéciaux - Colonnes, panneaux et structures de sol-ciment réalisés par jetAusführung von besonderen geotechnischen Arbeiten (Spezialtiefbau) - Düsenstrahlverfahren (Hochdruckinjektion, Hochdruckbodenvermörtelung, Jetting)93.020Zemeljska dela. Izkopavanja. Gradnja temeljev. Dela pod zemljoEarthworks. Excavations. Foundation construction. Underground worksICS:SIST EN 12716:2002enTa slovenski standard je istoveten z:EN 12716:200101-julij-2002SIST EN 12716:2002SLOVENSKI
STANDARD
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 12716May 2001ICS 93.020English versionExecution of special geotechnical works - Jet groutingExécution des travaux géotechniques spéciaux - Colonnes,panneaux et structures de sol-ciment réalisés par jetAusführung von besonderen geotechnischen Arbeiten(Spezialtiefbau) - Düsenstrahlverfahren(Hochdruckinjektion, Hochdruckbodenvermörtelung,Jetting)This European Standard was approved by CEN on 16 April 2001.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the 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 translationunder the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2001 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 12716:2001 E
Page 2EN 12716:2001ContentspageForeword.31Scope.42Normative references.43Terms and definitions.44Specific needs.115Geotechnical investigation.126Materials.137Design considerations.147.1General.147.2Geometry.177.3Strength and Deformation Characteristics.177.4Permeability.178Execution.188.1General.188.2Equipment.198.3Preliminary works.208.4Drilling.208.5Jet grouting.218.6Spoil Return.218.7Placing the reinforcement.219Supervision, testing and monitoring.219.1General.219.2Preliminary tests.229.3Supervision and process testing.229.4Testing on the constructed elements.239.5Monitoring.2410Execution documents.2410.1Documents available on site.2410.2Documents to be produced on site.2511Special requirements.2511.1Compliance with national standards.2511.2Site safety.2511.3Protection of the environment.26Annex A (normative)
Additional design requirements.27Annex B (informative)
Ranges of jet grouting parameters.28Annex C (informative)
Indirect tests.29Annex D (informative)
Examples of site records of jet grouting works.30Annex E (informative)
Degree of obligation of the provisions.33Bibliography.35
Page 3EN 12716:2001ForewordThis European Standard has been prepared by Technical Committee CEN /TC 288, "Execution of specialgeotechnical 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 orby endorsement, at the latest by November 2001, and conflicting national standards shall be withdrawn at the latestby November 2001.Annex A is normative, and the annexes B, C, D and E are informative.According to the CEN/CENELEC Internal Regulations, the national standards organizations of the followingcountries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland,France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden,Switzerland and the United Kingdom.
Page 4EN 12716:20011 ScopeThis Standard is applicable to the execution, testing and monitoring of jet grouting works. Design considerations,strictly related to jet grouting works only, are given in clause 7. More general requirements that could be includedin, or substituted by clauses of future editions of Eurocode 7 are listed in Annex A.NOTEThe jet grouting processes should be distinguished from the grouting processes covered by EN 12715.2 Normative referencesThis European Standard incorporates by dated or undated reference, provisions from other publications. Thesenormative references are cited at the appropriate places in the text and the publications are listed hereafter. Fordated references, subsequent amendments to or revisions of any of these publications apply to this EuropeanStandard only when incorporated in it by amendment or revision. For undated references the latest edition of thepublication referred to applies (including amendments).ENV 197-1:1992, Cement - Composition, specifications and conformity criteria - Part 1: Common cementsprEN 1008:1997, Mixing water for concrete - Specification for sampling, testing and assessing the suitability ofwater, including wash water from recycling installations in the concrete industry, as mixing water for concreteENV 1992-1-1:1991, Eurocode 2: Design of concrete structures - Part 1: General rules and rules for buildingsENV 1997-1:1994, Eurocode 7: Geotechnical design - Part 1: General rules3 Terms and definitionsFor the purposes of this European Standard, the following terms and definitions apply:3.1jet groutingthe jet grouting process consists of the disaggregation of the soil or weak rock and its mixing with, and partialreplacement by, a cementing agent; the disaggregation is achieved by means of a high energy jet of a fluid whichcan be the cementing agent itself3.2jet grouted elementa volume of soil treated through a single borehole. The most common elements are : jet grouted column : a cylindrical jet grouted element (Fig.1 a) ; jet grouted panel : a planar jet grouted element (Fig.1 b).3.3jet grouted structurean assembly of jet grouted elements which are partially or fully interlocked. The most common structures formedare : jet grouted diaphragm : a wall structure (Fig.2 a) ; jet grouted slab : a horizontal structure formed by essentially vertical jet grouting (Fig.2 b) ; jet grouted canopy : a structure formed by horizontal jet grouting – see 3.8 below (Fig.2 c) ; jet grouted block : a three-dimensional structure.
Page 5EN 12716:20013.4single systemthe jet grouting process in which the disaggregation and cementation of soil are achieved by a high energy jet of asingle fluid, usually a cement grout (Fig.3 a)3.5double (air) systemthe jet grouting process in which the disaggregation and the cementation of soil are achieved by one high energyfluid (usually a cement grout) assisted by an air jet shroud as a second fluid (Fig.3 b)3.6double (water) systemthe jet grouting process in which the disaggregation of the soil is achieved by a high energy water jet and itscementing is simultaneously obtained by a separate grout jet (Fig.3 c)3.7triple systemthe jet grouting process in which the disaggregation of the soil is achieved by a high energy water jet assisted byan air jet shroud, and its cementing is simultaneously obtained by a separate grout jet (Fig.3 d)NOTEIn special cases the water can be substituted
for other appropriate liquids or suspensions.3.8horizontal jet groutingtreatment performed from a horizontal or sub-horizontal borehole (within ± 20° from the horizontal plane)3.9jet grouting rigrotary rig able to automatically regulate the rotation and translation of the jet grouting string and tool3.10jet grouting stringjointed rods, with simple, double or triple inner conduit, which convey the jet grouting fluid(s) to the monitor3.11monitorthe tool mounted at the end of the jet grouting string, to enable jetting of the fluids into the ground3.12nozzlea specially manufactured device fitted into the monitor and designed to transform the high pressure fluid flow in thestring into the high speed jet directed at the soil3.13radius of influenceeffective distance of disaggregation of soil by the jet, measured from the axis of the monitor3.14spoil returnthe surplus mixture of soil particles and introduced fluids arising from the jet grouting process, and normally flowingto the ground surface via the annulus of the jetting borehole3.15jet grouting parametersthe jet grouting parameters are defined : pressure of the fluid(s) within the jet grouting string ; flow rate of the fluid(s) within the jet grouting string ; grout composition ; rotation speed of the jet grouting string ;
Page 6EN 12716:2001 rate of withdrawal or insertion of the jet grouting string.3.16prejettingthe method in which the jet grouting of an element is facilitated by a preliminary disaggregation phase, with a jet ofwater and/or other fluidsNOTEPrejetting is also widely known as prewashing or precutting.3.17fresh-in-fresh sequencethe sequence of work in which the jet grouted elements are constructed successively without waiting for the groutto harden in the overlapping elements (Fig.4 a)3.18primary-secondary sequencethe sequence of work in which the execution of an overlapping element cannot commence before a specifiedhardening time or achievement of predetermined strength of the adjacent elements previously constructed (Fig.4 b)3.19jet grouted materialthe material which constitutes the body of a jet grouted element3.20reinforced jet groutingjet grouted columns reinforced by steel or other high strength material
Page 7EN 12716:2001Figure 1 a) — Jet grouted columnFigure 1 b) — Jet grouted panelFigure 1 — Examples of jet grouted elementsFigure 2 a) — Jet grouted diaphragms
Page 8EN 12716:2001Figure 2 b) — Jet grouted slabFigure 2 c) — Jet grouted canopyFigure 2 — Examples of jet grouted structuresKey1 MonitorFigure 3 a) — Single system
Page 9EN 12716:2001Key1 MonitorFigure 3 b) — Double (air) systemKey1 MonitorFigure 3 c) — Double (water) system
Page 10EN 12716:2001Key1 MonitorFigure 3 d) — Triple systemFigure 3 — Schemes of jet grouting systemsFigure 4 a) — Fresh in fresh sequenceFigure 4 b) — Primary – secondary sequenceFigure 4 — Work sequences
Page 11EN 12716:20014 Specific needs4.1The following information shall be determined prior to design or execution activities : detailed description of the ground profile and its geotechnical properties within the intended extent oftreatment ;and, as appropriate : hydrogeological conditions ; boundary conditions (adjacent structures, buried structures and services, overhead power lines and other workingrestrictions, access) ; environmental requirements; in particular disposal of spoil return ; acceptable deformation of the structures to be underpinned or of adjacent structures.4.2Design assumptions according to ENV 1997-1-1:1994 - clause 2 shall be verified, and modified if necessary,according to information obtained during the execution phase.4.3Due to the nature of jet grouting works, the client, the main contractor, a specialist contractor or a consultingengineer, may perform all or parts of the design.4.4The allocation of design, execution and supervision activities and responsibilities of all the parties involvedshall be legibly specified in the contract documents.4.5Design and execution should include, as appropriate, the activities listed in table 1. The order shown doesnot necessarily represent a time sequence.
Page 12EN 12716:2001Table 1 — Recommended list of activities in the design and execution of jet groutingN°Activity1Provision of site investigation data for execution of jet grouting works.2Decision to use jet grouting, preliminary trials and testing if required ; provision of a specification.3Acquisition of all legal authorization necessary for the execution from authorities and third parties.4Overall design of jet grouted structure and definition of the geotechnical category.5Consideration of the relevant temporary phases of execution.6Assessment of the site investigation data with respect to design assumptions.7Assessment of the construction feasibility of the design.8Execution of trials if required and of any relevant tests.9Evaluation of the results of the preliminary trials and tests.10Selection of jet grouting system.11Assessment of the jet grouting system and definition of the working procedures.12Definition of the dimensions, location and orientation of jet grouted elements.13Instructions regarding the working sequence if required.14Definition of the working sequence.15Instruction to all parties involved of key items in the design criteria to which special attention should be directed.16Specification for monitoring the effects of jet grouting works on adjacent structures (type and accuracy ofinstruments, frequency of measurement) and for interpreting the results.17Definition of tolerable limits of the effects of jet grouting works on adjacent structures.18Execution of the jet grouting works, including monitoring of the jet grouting parameters.19Supervision of the works, including the definition of the quality requirements.20Monitoring the effects of jet grouting works on adjacent structures and presenting the results.21Control of the quality of works.5 Geotechnical investigation5.1Jet grouting is a ground treatment method and shall be designed on the basis of the geotechnical chara-cteristics of the ground ; therefore an accurate geotechnical investigation is essential.5.2All geotechnical investigation shall be undertaken in accordance with the requirements andrecommendations of ENV 1997-1:1994, in particular with reference to the geotechnical categories in points 2.1,3.2, and 3.3.5.3Where possible geotechnical investigation should be extended to the site boundaries so that the soil profilecan be interpolated between the investigated axes rather than extrapolated outside them.5.4Special consideration shall be given to the following geotechnical conditions : firm or stiff cohesive layers or lenses ; high organic content ; swelling soils ; highly sensitive or quick clays ; cemented layers or lenses ; position of water table(s) ;
Page 13EN 12716:2001 presence of artesian or confined aquifer conditions ; high hydraulic gradients ; aggressive soil or water ; density of granular layers ; cobbles and/or boulders ; large voids or high permeability ; chemical wastes or deposits.5.5In addition to the lithology and structure of the ground in accordance with ENV 1997-1:1994, the followingfeatures and parameters shall also be determined, through laboratory and/or in situ tests, as applicable : grain size distribution, moisture content, Atterberg limits ; density, by direct or indirect measurement ; shear strength, by direct or indirect measurement.5.6In situ mechanical testing of the soil should be used to identify variations of density.6 Materials6.1Unless otherwise specified, the properties of the materials shall comply with European standards.6.2Mixes composed of water and cement are usually adopted.6.3Hydraulic binders other than cement can be used.6.4In water/cement mixes the water/cement ratio by weight should range between 0,5 and 1,5.6.5Water reducing, stabilizing, plasticising, waterproofing or antiwashing admixtures can be added to thewater/cement mix.6.6Other materials, such as bentonite, filler, fly-ash, can also be added to the mix.6.7When bentonite is to be used in the mix, a water/bentonite suspension should be prepared before addingcement.6.8Any recognized potable water is normally acceptable for the preparation of jet grouting mixes.6.9Water from sources other than recognized potable water suppliers shall be analysed in order to ensure that itwill have no adverse effect on the setting, hardening or durability of the mix and, where applicable, will not promotecorrosion of the reinforcement.6.10If the cement does not comply with the standard ENV 197-1:1992, appropriate tests shall be performed inorder to ensure that the setting time, hardening, strength and durability requirements, as stated by designspecifications, are met.6.11Care should be taken to ensure that no large particles are present in the jetting materials, as they can blockthe nozzles.6.12Acceptance criteria and water testing methods as required by subclause 6.9. shall conform to prEN1008:1997.6.13Where reinforcement is obtained by steel bars, the material shall comply with ENV 1992-1-1:1991 - clause 3and 6 as appropriate.
Page 14EN 12716:20016.14Where material other than steel bars is used for reinforcement, it shall comply with national standards or withdesign technical specifications.7 Design considerations7.1 General7.1.1Jet grouting can be applied in either temporary or permanent works for different purposes. For example : providing foundations for structures to be erected (Fig.5 a) ; underpinning existing foundations (Fig.5 b) ; creating low permeability barriers ; creating retaining or supporting structures ; complementing other geotechnical works ; reinforcing a soil mass.7.1.2The design of jet grouting works should specify that borehole collars are to be located above the watertable.7.1.3Wherever the borehole collars are located below the water table or artesian head, special measures shallbe taken into account, in order to avoid piping through the boreholes.7.1.4The purpose of jet grouting works shall be clearly defined in the design. The specified physical propertiesand geometry of jet grouted elements or structures shall be appropriate for this purpose.7.1.5The technical conditions which may influence the working sequence of the elements shall be specified.7.1.6When relevant, the detailed execution sequence should be shown on the execution drawings.7.1.7If the design of the jet grouting works cannot be completed due to deficient site investigation, and it is notpossible to obtain the missing information by further soil investigation, an appropriate preliminary field test shall bespecified.7.1.8Where no comparable previous experience is available representative preliminary field test shall be carried out,using the equipment, materials and techniques proposed for the main jet grouting works.7.1.9To ensure a consistent result in the preliminary in-situ trial, at least one jet grouted element should beconstructed with a given working procedure. In significantly heterogeneous soil conditions more trial elements anddifferent working procedures should be necessary for approval.7.1.10Where the jet grouted material is to be subjected to onerous conditions, such as high stresses orresistance to aggressive environments, the preliminary in-situ tests should be preceded by specified laboratorytests on samples of the soil to be treated and the grout, mixed in proportions encompassing the working rangeenvisaged.7.1.11For mechanical tests on jet grouted material the conditions for testing the samples and the criteria foracceptance shall be specified.7.1.12Tolerances on specified performance parameters should take into account the accuracy of the proposedtest methods, especially when these methods are indirect, as quoted in Annex C.7.1.13Whenever acceptance is defined on the basis of tests on core samples, the criteria for positioning and timing ofthe proposed corings in the jet grouted structure shall be specified in the design.7.1.14Design parameters should take account of construction difficulties which may reduce the effectiveness ofthe jet grouting.
Page 15EN 12716:20017.1.15Sequence and rate of execution, setting and hardening time, and diameter of columns shall be considered inorder to avoid local soil failures or unacceptable settlement or uplift.7.1.16The design should define the acceptable limits of settlement, heave, distortion of structures and services likelyto be affected by the jet grouted works.7.1.17The design of jet grouting works shall comply with Annex A.
Page 16EN 12716:2001Figure 5 a) — Foundation for structure to be erectedFigure 5 b) — Underpinning existing foundationFigure 5 — Examples of applications
Page 17EN 12716:20017.2 Geometry7.2.1The cross-sectional dimensions of a jet grouted element depend not only on the jet grouting systemselected and on the parameters employed, but also on the soil type and its heterogeneity.7.2.2The design shall take into account the construction tolerances indicated in 8.4.3, 8.4.4, and 8.5.6, or shallpropose different values for them.7.2.3The following shall be clearly shown on design drawings : minimum cross sectional dimensions of jet grouted elements to be achieved in the different soil layers that willbe encountered ; tolerances on the position and inclination of the element axes (see 8.4.3 and 8.4.4).7.2.4Maximum cross sectional dimensions should also be considered and related to the element spacing toensure the integrity of a jet grouted structure.7.2.5If any identified underground obstruction cannot be removed, the relevant area shall be marked on thedesign drawings, and the adjacent jet grouting treatment shall be designed so as to avoid unacceptable damage.7.3 Strength and Deformation Characteristics7.3.1The strength of a jet grouted material depends both on the jet grouting system selected and on theparameters employed, and also on the soil type and its heterogeneity.7.3.2In underpinning applications stability and deformation in the temporary condition, prior to set, of the jetgrouted columns beneath foundations shall be taken into account.7.3.3Where deformations of jet grouted elements or of jet grouted structures are an important concern, thedesign shall indicate the parameters to be measured in specified acceptance tests, the range of their values andthe relevant mean values (mean on the element, on larger parts of the structure, on the whole structure).7.3.4The required statistical minimum strength of the mass should be established at the design stage, takinginto consideration the variability of the soil conditions.7.3.5In many cases a practical degree of scatter will be unable to be set due to limited previous experience. Inthese circumstances a scatter can only be identified by on site tests.7.3.6Where indirect testing is to be used for checking the results the acceptance criteria shall be expressed inthe design in terms of the actual parameters to be measured.7.3.7The jet grouted columns can be reinforced by high strength elements (bars, pipes, beams), installed duringor after jet grouting operations.7.4 Permeability7.4.1Where jet grouting works are employed to control groundwater, the results depend on the geometricaccuracy of the elements and on the permeability of the jet grouted material.7.4.2Permeability requirements shall be expressed in the design in terms of limit values of parameters actuallymeasured in specified acceptance tests.The design shall specify the conditions of measurement of the jet grouted material permeability, and of the overalljet grouted structure.7.4.3The overall permeability of a jet grouted structure should be evaluated taking into account the effects ofdeformation due to excavation or to loading conditions at full scale.
Page 18EN 12716:20018 Execution8.1 General8.1.1The execution of jet grouting works requires knowledge and experience in this type of construction.NOTEThe high pressure employed in the jet grouting process is to generate a high speed jet to disaggregate the soil andis not intended to be applied to the surrounding soil.8.1.2Jet grouted column execution methodThe phases of execution usually consist of : drilling a borehole of a predetermined length ; introducing to the end of the borehole a monitor connected to the jet grouting string. This is unnecessary insome cases as the string and monitor are used for drilling ; jetting of the disaggregating and cementing fluid(s) through the monitor, simultaneously withdrawing androtating the rods, with pre-established withdrawal and rotational speed, pump pressure and flow rate for eachfluid.8.1.3Jet grouted panel execution methodThe phases of execution are the same as defined for jet grouted columns, with the exception that during jetting therods are withdrawn and not rotated. Alternatively the rods can be rotated about limited angles. The resulting panelis placed in a plane on the drilling axis, or is formed by two or more sections on planes intersecting the drilling axis(Fig.1 b).8.1.4Alternative execution methodsIf required by soil conditions, alternative execution methods may be adopted, both for column or panel processes.Among alternatives the most usual is prejetting. An element can also be executed in sequential steps: firstly thetreatment for a given length from the
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