Execution of special geotechnical works – Deep mixing

Scope

This European Standard establishes general principles for the execution, testing, supervision and monitoring of deep mixing works carried out by two different methods : dry mixing and wet mixing. Deep mixing considered in this Standard is limited to methods, which involve : a) mixing by rotating mechanical mixing tools (see Annex A) where the lateral support provided to the surrounding soil is not removed ; b) treatment of the soil to a minimum depth of 3 m ;

different shapes and configurations, consisting of either single columns, panels, grids, blocks, walls or any combination of more than one single column, overlapping or not (see Annex A) ; d) treatment of natural soil, fill, waste deposits and slurries, etc. ; e) other ground improvement methods using similar techniques exist, which are only partly covered by this standard (see Annex A). Guidance on practical aspects of deep mixing, such as execution procedures and equipment, is given in Annex A. Methods of testing, specification and assessment of design parameters, which are affected by execution, are presented in Annex B. 2

Normative references

This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision.

For undated references the latest edition of the publication referred to applies (including amendments). EN 196-1, Methods of testing cement — Part 1 : Determination of strength. EN 196-2, Methods of testing cement — Part 2 : Chemical analysis of cement. EN 196-3, Methods of testing cement — Part 3 : Determination of setting time and soundness. EN 196-4, Methods of testing cement — Part 4 : Quality determination of constituents. EN 196-5, Methods of testing cement

— Part 5 : Pozzolanicity tests for pozzolanic cement. EN 196-6, Methods of testing cement — Determination of fineness. EN 196-7, Methods of testing cement — Methods of taking and preparing samples of cement. EN 196-21, Methods of testing cement — Determination of the chloride, carbon dioxide and alkali content of cement. EN 197-1:2000, Cement — Composition, specification and conformity criteria — Part 1 : Common cements. EN 197-2:2000, Cement — Composition, specification and conformity criteria — Part 2 : Conformity evaluation. EN 451, Methods of testing fly ash. EN 459-1, Building lime — Part 1 : Definitions, specifications and conformity criteria. EN 459-2, Building lime — Part 2 : Test methods. 4 prEN 14679:2003 (E) ENV 1991,

Eurocode 1 : Basis of design and actions on structures. ENV 10080, Steel for reinforcement of concrete, wieldable ribbed reinforcing steel B 500 — Technical delivery conditions for bars, coils and welded fabric. ENV 791:1996, Drill rigs — Safety. ENV 1997-1, Eurocode 7 : Geotechnical design — Part 1 : General rules. ENV 1997-2, Eurocode 7 : Geotechnical design — Part 2 : Design assisted by laboratory testing. ENV 1997-3, Eurocode 7 : Geotechnical design — Part 3 : Design assisted by field testing. prEN 196-8, Methods of testing cement — Part 8 : Determination of heat of hydration. ISO/DIS 14688-1-2,

Identification and classification of soil. ISO/DIS 14689, Identification and description of rock. 3 Terms and definitions For the purposes of this European Standard, the following terms and definitions apply. 3.1 admixture fr : additive, Addition dispersant, fluidifier, retarding agent 3.2 binder fr : liant de : Zusatzmittel de : Bindemittel chemically reactive materials (lime, cement, gypsum, blast furnace slag, fly ash, etc.) 3.3 binder content fr : teneur pondéral en liant de : Bindemittelgehalt the weight of dry binder introduced per unit volume of soil to be treated 3.4 binder factor fr : dosage volumique de liant de : Bindemittelfaktor the ratio of the weight of dry binder introduced to the dry weight of the soil to be treated 3.5 column fr : colonne de : Säule a pillar of treated soil manufactured in situ by a single installation process using a mixing tool.

The mixing tool and the execution process govern the shape and size of the cross section of a column 3.6 dry mixing fr : malaxage par voie sèche de : Trockenmischverfahren a process consisting of mechanical desegregation of the soil in-situ and its mixing with binders with or without fillers and admixtures in dry powder form 5 prEN 14679:2003 (E) 3.7 filler fr : fines inerte, charge inerte a non-reacting material (sand, limestone powder etc.) 3.8 mixing process fr : processus de malaxage de : Füller de : Mischvorgang the mixing process involves mechanical disaggregation of the soil structure, dispersion of binders and fillers in the soil 3.9 mixing tool fr : outil de malaxage de : Mischwerkzeug a tool used to disaggregate the soil, distribute and mix the binder with the soil, consisting of one or several rotating units equipped with several blades, arms, paddles with/without continuous or discontinuous flight augers (see Annex A)

penetration (Downstroke) fr : enfoncement (descente de l’outillage) de : Abbohrvorgang the stage/phase of mixing process cycle, in which the mixing tool is delivered to the appropriate depth and initial mixing and fluidisation of the soil take place 3.11 penetration or Retrieval speed fr : vitesse d’enfoncement ou de remontée de : Abbohr- bzw. Ziehgeschwindikeit vertical movement per unit time of the mixing tool during penetration or retrieval 3.12 penetration or retrieval rate fr : vitesse d’enfoncement ou de remontée par tour de : Abbohr- bzw. Ziehrate vertical movement of the mixing tool per revolution of the rotating unit(s) during penetration or retrieval

retrieval (Upstroke) fr : remontée (montée de l’outillage) de : Ziehvorgang the stage/phase of mixing process cycle, in which the final mixing and retrieval of the mixing tool take place 3.14 restroke fr : re-malaxage de : wiederholter Mischvorgang restroke is an additional penetration and retrieval cycle of the mixing tool 3.15 rotation speed fr : vitesse de rotation de : Umdrehungsgeschwindigkeit number of revolutions of the rotating unit(s) of the mixing tool per unit time 3.16 stroke fr : malaxage one complete cycle of the mixing process 3.17 volume ratio fr : teneur volumique en coulis de : Mischvorgang de : Volumenverhältnis the ratio of the volume of slurry injected (in wet mixing) to the volume of soil to be treated.