Execution of special geotechnical works - Vertical drainage

This European Standard establishes general principles for the execution, testing, supervision and monitoring of vertical drain projects.
This European Standard includes the application of prefabricated vertical drains and sand drains and deals with requirements to be placed on design, drain material and installation methods. This European Standard applies to the improvement of low-permeability, highly compressible soils by vertical drainage and preloading. Information regarding loading (embankment, vacuum or ground water lowering) and preloading is given in informative Annexes A and B.
Vertical drainage is used both in on land and in marine constructions for the following purposes:
   (pre-)consolidation and reduction of post-construction settlements;
   speeding up the consolidation process by decreasing the path lengths for pore water dissipation;
   increase of stability (by increasing effective stresses in the soil);
   groundwater lowering;
   mitigation of liquefaction effects.
In each case there is an overall treatment of the soil (the volume of the drains is small in relation to the soil volume treated).
This European Standard does not include soil improvement by means of wells, gravel and stone columns, large-diameter geotextile enclosed columns or reinforcing elements.
Vertical drainage can also be combined with other foundation or ground improvement methods, e.g. electro osmosis, piles and compacted sand piles, dynamic compaction and deep mixing.
Guidance on practical aspects of vertical drainage, such as investigation of drain properties, execution procedures and equipment, is given in Annex A. Investigation of soil characteristics and assessment of design parameters, which are affected by drain properties and execution, are presented in Annex B.

Ausführung von besonderen geotechnischen Arbeiten (Spezialtiefbau) - Vertikaldräns

Diese Europäische Norm legt die allgemeinen Grundsätze für die Ausführung, Prüfung, Bauaufsicht und Überwachung von Projekten für Vertikaldräns fest.
Diese Europäische Norm umfasst die Anwendung vorgefertigter Vertikaldräns und Sanddräns und behandelt Anforderungen an Bemessung, Dränmaterialien sowie an Einbauverfahren. Diese Europäische Norm ist auf die Verbesserung schwach durchlässiger, stark komprimierbarer Böden durch Vertikaldränung und Vorbe¬lastung anwendbar. Informationen bezüglich der Belastung (Damm, Vakuum oder Grundwasserabsenkung) und der Vorbelastung sind in den informativen Anhängen A und B angegeben.
Die Vertikaldränung wird sowohl bei Bauwerken an Land als auch bei Meeres- bzw. Seebauwerken angewendet, wobei folgende Zwecke verfolgt werden:
   (Vor )Konsolidierung und Verringerung von Setzungen nach dem Errichten des Bauwerkes;
   Beschleunigen des Konsolidationsprozesses durch Verringerung der Pfadlängen für den Porenwasser¬abfluss;
   Erhöhung der Standsicherheit/Stabilität (durch Erhöhung der wirksamen Spannungen im Boden);
   Grundwasserabsenkung;
   Abschwächen von Verflüssigungswirkungen.
                In jedem Fall findet eine Gesamtbehandlung des Bodens statt (das Volumen der Dräns ist im Verhältnis zum behandelten Bodenvolumen gering).
Diese Europäische Norm behandelt nicht die Verbesserung des Bodens mit Hilfe von Brunnen, Kies  und Steinsäulen, geotextilumschlossenen Säulen mit großem Durchmesser oder Bewehrungselementen.
Die Vertikaldränung kann auch mit weiteren Gründungs  oder Bodenverbesserungsverfahren, wie z. B. Elektro Osmose, Pfähle und verdichtete Sandpfähle, Fallplattenverdichtung und tiefreichende Bodenstabili¬sierung, kombiniert werden.

Exécution des travaux géotechniques spéciaux - Drains verticaux

La présente Norme européenne établit les principes généraux pour l'exécution, les essais de contrôle, la surveillance et le suivi des travaux de réseaux de drains verticaux.
Cette Norme européenne couvre aussi bien les travaux réalisés avec des drains préfabriqués que ceux réalisés avec des drains de sable et elle traite des exigences pour la conception des travaux, les matériaux constitutifs des drains, et les méthodes de mise en place. La présente norme s’applique aux travaux d’amélioration des sols de faible perméabilité et fortement compressibles, par pré-chargement du terrain associé à un réseau de drains verticaux. Des indications relatives au chargement d’un terrain (avec un remblai, par consolidation atmosphérique ou par rabattement de la nappe) sont données dans les Annexes informatives A et B.
Les techniques d’amélioration des massifs de sol avec des réseaux de drains verticaux sont utilisées aussi bien pour les projets en site terrestre que pour les projets en conditions maritimes dans les buts suivants :
   (pré-)consolider un massif au droit d’un futur ouvrage pour réduire les tassements après sa construction ;
   accélérer le processus de consolidation d'un massif, c’est à dire le processus de dissipation des pressions interstitielles à l’intérieur de celui-ci, en réduisant le trajet d’écoulement des eaux ;
   améliorer la résistance d'un massif (en augmentant les contraintes effectives dans celui-ci) ;
   rabattre le niveau d'une nappe ;
   réduire le potentiel de liquéfaction d'un massif.
Pour toutes ces applications, un traitement d’ensemble du massif est réalisé (le volume des drains est faible par rapport au volume de sol traité).
La présente Norme européenne ne couvre pas l'amélioration des massifs de sol au moyen de puits, de colonnes ballastées, de colonnes de sable de grand diamètre dans une gaine géotextile ou d’inclusions rigides.

Izvedba posebnih geotehničnih del - Navpično odvodnjavanje

General Information

Status
Published
Publication Date
27-Feb-2007
Withdrawal Date
30-Aug-2007
ICS
93.020 - Earthworks. Excavations. Foundation construction. Underground works
Technical Committee
CEN/TC 288 - Execution of special geotechnical works
Drafting Committee
CEN/TC 288/WG 11 - Vertical drains
Current Stage
9093 - Decision to confirm - Review Enquiry
Start Date
11-Mar-2024
Completion Date
14-Apr-2025
Ref Project
SIST EN 15237:2007 - Execution of special geotechnical works - Vertical drainage

Overview

EN 15237:2007 - Execution of special geotechnical works - Vertical drainage (CEN) establishes the European principles for planning, execution, testing, supervision and monitoring of vertical drainage projects. It covers the use of prefabricated vertical drains (PVDs) and sand drains to improve low‑permeability, highly compressible soils by vertical drainage and preloading. Informative Annex A gives practical guidance on drain properties and installation procedures; Annex B addresses investigation of soil characteristics and design parameters.

Key topics and requirements

  • Scope and exclusions
    • Applies to on‑land and marine works for (pre‑)consolidation, settlement reduction, accelerated consolidation, stability increase, groundwater lowering and liquefaction mitigation.
    • Does not cover wells, gravel/stone columns, large‑diameter geotextile‑enclosed columns or reinforcing elements.
  • Design and investigation
    • Requirements for geotechnical site investigation to define stratigraphy, piezometric levels and undrained shear strength (see Annex B).
    • Field trials recommended to verify installation method and performance.
  • Drain materials and products
    • Specification and testing requirements for band drains, cylindrical prefabricated drains and sand drains, including filter properties and discharge capacity.
    • Reference to CE‑marking documentation and applicable geosynthetic test standards.
  • Installation methods
    • Accepted methods described include displacement (static), auger, vibro, jet, dynamic (impact/vibration) and combinations tailored to ground conditions.
    • Guidance on working platform, drainage blanket, anchors and special installation aspects (Annex A).
  • Quality control, supervision and monitoring
    • Clear requirements for method statements, on‑site supervision, construction records, acceptance testing and monitoring programs during preloading (embankment, vacuum or groundwater lowering).
  • Health, safety and environment
    • Provisions for safety, environmental protection and managing impacts on adjacent structures.

Applications and users

Practical applications:

  • Accelerating consolidation of compressible clays beneath embankments, roads, ports and reclamations
  • Reducing post‑construction settlement and improving stability for foundation works
  • Groundwater lowering and liquefaction mitigation in seismic areas

Primary users:

  • Geotechnical and civil engineers, contractors and site supervisors
  • Project managers, clients and regulators specifying ground improvement works
  • Laboratory and field testing specialists involved in drain acceptance and monitoring

Related standards

  • EN 1997‑1 & EN 1997‑2 (Eurocode 7: Geotechnical design and ground investigation) - EN 15237 is intended to complement these Eurocode modules.
  • Relevant geotextile/geosynthetic standards cited within EN 15237 for material testing and identification.

Keywords: EN 15237:2007, vertical drainage, prefabricated vertical drains, sand drains, preloading, consolidation, drain installation, geotechnical standard, CEN.

Frequently Asked Questions

EN 15237:2007 is a standard published by the European Committee for Standardization (CEN). Its full title is "Execution of special geotechnical works - Vertical drainage". This standard covers: This European Standard establishes general principles for the execution, testing, supervision and monitoring of vertical drain projects. This European Standard includes the application of prefabricated vertical drains and sand drains and deals with requirements to be placed on design, drain material and installation methods. This European Standard applies to the improvement of low-permeability, highly compressible soils by vertical drainage and preloading. Information regarding loading (embankment, vacuum or ground water lowering) and preloading is given in informative Annexes A and B. Vertical drainage is used both in on land and in marine constructions for the following purposes:  (pre-)consolidation and reduction of post-construction settlements;  speeding up the consolidation process by decreasing the path lengths for pore water dissipation;  increase of stability (by increasing effective stresses in the soil);  groundwater lowering;  mitigation of liquefaction effects. In each case there is an overall treatment of the soil (the volume of the drains is small in relation to the soil volume treated). This European Standard does not include soil improvement by means of wells, gravel and stone columns, large-diameter geotextile enclosed columns or reinforcing elements. Vertical drainage can also be combined with other foundation or ground improvement methods, e.g. electro osmosis, piles and compacted sand piles, dynamic compaction and deep mixing. Guidance on practical aspects of vertical drainage, such as investigation of drain properties, execution procedures and equipment, is given in Annex A. Investigation of soil characteristics and assessment of design parameters, which are affected by drain properties and execution, are presented in Annex B.

This European Standard establishes general principles for the execution, testing, supervision and monitoring of vertical drain projects. This European Standard includes the application of prefabricated vertical drains and sand drains and deals with requirements to be placed on design, drain material and installation methods. This European Standard applies to the improvement of low-permeability, highly compressible soils by vertical drainage and preloading. Information regarding loading (embankment, vacuum or ground water lowering) and preloading is given in informative Annexes A and B. Vertical drainage is used both in on land and in marine constructions for the following purposes:  (pre-)consolidation and reduction of post-construction settlements;  speeding up the consolidation process by decreasing the path lengths for pore water dissipation;  increase of stability (by increasing effective stresses in the soil);  groundwater lowering;  mitigation of liquefaction effects. In each case there is an overall treatment of the soil (the volume of the drains is small in relation to the soil volume treated). This European Standard does not include soil improvement by means of wells, gravel and stone columns, large-diameter geotextile enclosed columns or reinforcing elements. Vertical drainage can also be combined with other foundation or ground improvement methods, e.g. electro osmosis, piles and compacted sand piles, dynamic compaction and deep mixing. Guidance on practical aspects of vertical drainage, such as investigation of drain properties, execution procedures and equipment, is given in Annex A. Investigation of soil characteristics and assessment of design parameters, which are affected by drain properties and execution, are presented in Annex B.

EN 15237:2007 is classified under the following ICS (International Classification for Standards) categories: 93.020 - Earthworks. Excavations. Foundation construction. Underground works. The ICS classification helps identify the subject area and facilitates finding related standards.

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Standards Content (Sample)


2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Execution of special geotechnical works - Vertical drainageExécution des travaux géotechniques spéciaux - Drains verticauxAusführung von besonderen geotechnischen Arbeiten (Spezialtiefbau) - VertikaldränsTa slovenski standard je istoveten z:EN 15237:2007SIST EN 15237:2007en;fr;de93.020Zemeljska dela. Izkopavanja. Gradnja temeljev. Dela pod zemljoEarthworks. Excavations. Foundation construction. Underground worksICS:SLOVENSKI
STANDARDSIST EN 15237:200701-julij-2007

EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 15237February 2007ICS 93.020 English VersionExecution of special geotechnical works - Vertical drainageExécution des travaux géotechniques spéciaux - DrainsverticauxAusführung von besonderen geotechnischen Arbeiten(Spezialtiefbau) - VertikaldränsThis European Standard was approved by CEN on 7 January 2007.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 CEN 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 CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2007 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 15237:2007: E

Practical aspects of vertical drainage.20 Annex B (informative)
Aspects of design.41 Annex C (informative)
Degree of obligation of the specifications.52 Bibliography.54

1) The terms “wick drains” and “prefabricated vertical drains” (PVD) are also used.

(20 % if exposed to frost); c) minimum tensile force > 1,5 kN at failure of the weakest element. The seam should not fail during the test. NOTE These values depend on the installation equipment and procedure and may need to be adjusted accordingly. 6.3.4.4 The strength of the seam, measured according to EN ISO 10321 in a range of temperatures, which apply to the project site, shall be at least 1 kN/m. 6.3.5 Discharge capacity 6.3.5.1 The discharge capacity and the filtration characteristics are the most important properties. The following factors influence the discharge capacity: a) due to increasing lateral effective pressure during the consolidation process the filter is squeezed into the channel system of the core, which reduces the channel area; b) the vertical compression of the soil taking place during the consolidation process may lead to buckling of the relatively incompressible band drains, which may reduce the channel area;

6.3.6.2 The filter sleeve should have a regular structure. 6.3.6.3 The occurrence of creases, tears, holes and/or other defects shall not be allowed. The seams of the filter sleeve shall be constructed in such a way that fines cannot intrude into the core of the band drain. 6.3.6.4 Visual inspections for damage shall be made regularly during production in accordance with the factory production control plan. 6.3.7 Tensile strength per unit width of filter 6.3.7.1 The tensile strength of the filter shall be sufficient to prevent breakage during and after installation. 6.3.7.2 Testing should be carried out in accordance with EN ISO 10319. The average of the individually measured values for the tensile strength should not be lower than 3 kN/m in the longitudinal direction. For installations deeper than 25 m or in difficult soil conditions, a minimum tensile strength of 6 kN/m in the longitudinal direction is recommended. 6.3.8 Velocity index of filter Testing should be carried out in accordance with EN ISO 11058. The average of the individually measured values of the velocity index (vh50) should be higher than 1 mm/s. In case of drain installation for liquefaction problems, the filter pore size should be adapted to ensure adequate permeability of the filter for this application, see 6.4.

Quality control 6.3.10.1 The band drain shall comply with all European requirements and conformity assessment procedures that apply to it. The properties shall be within the limits announced in the accompanying document accredited by a Notifying Body. 6.3.10.2 The filter and drain characteristics and corresponding testing methods, as well as the proposed testing frequency, are given in Table 1, adapted from EN 13252. The sampling procedure for the different testing methods shall comply with EN ISO 9862. NOTE The on-site testing frequency should be decided between the parties involved.

Thickness 25 000 m2 EN 9863-1 Mass per unit area 25 000 m2 EN 9864 Pore size 200 000 m2 EN 12956 Velocity index 200 000 m2 EN 11058 Tensile strength in the longitudinal direction 200 000 m2 EN 10319 Tensile strength in the cross direction 200 000 m2 EN 10319 Drain composite: Width and thickness 25 000 m EN 9863-1 Mass per unit length 25 000 m EN 9864 Tensile strength in the longitudinal direction 100 000 m EN 10319 Elongation at maximum tensile force 100 000 m EN 10319 Discharge capacity straight 500 000 m Annex A Discharge capacity buckled 500 000 m Annex A Tensile strength of filter seam 100 000 m EN 10321 Durability 500 000 m EN 13252 6.4 Prefabricated cylindrical drain 6.4.1 Shape and structure of cylindrical drains 6.4.1.1 A cylindrical drain consists of an annular-corrugated and perforated open core, surrounded by a filter sock. The drain diameter is typically 50 mm in outer diameter and 45 mm in inner diameter. 6.4.1.2 Tears and/or other defects shall not be allowed to occur. Visual inspections for damage shall be made regularly as part of the production quality control. 6.4.2 Measurements The diameter and thickness of the core should comply with the dimensions given by the manufacturer (within allowable deviations given by the manufacturer).
6.4.3 Durability 6.4.3.1 The durability of the drain shall comply with the durability aspects given in EN 13252 (Annex B, B.1 weathering, and B.2, required service lives up to five years or more when the drains are installed to mitigate soil liquefaction). 6.4.3.2 The drains should be protected against weathering during storage on the site. 6.4.3.3 The product shall not be exposed longer than the time announced by the producer for CE Marking (EN 13252) unless the product is protected by a wrapping material or stored in-house. The recommendations of the supplier shall be followed.

Quality control The prefabricated drain product shall comply with all European requirements and conformity assessment procedures that apply to it. The properties shall be within the limits announced in the accompanying document accredited by a Notifying Body. 6.5 Sand drains 6.5.1 The sand drain has a circular cross-section, built up of granular material with high permeability. The diameter of the sand drain can vary typically from 150 mm to 500 mm. 6.5.2 The grain size distribution of the material used for sand drains should preferably fall within the limits given in Annex A. 6.5.3 The permeability of the sand should be high enough to avoid significant well resistance. The permeability requirements depend on the permeability of the surrounding soil and the depth of drain installation (see Annex B) and should primarily be defined by the designer. 6.5.4 Material used for sand drains shall not cause pollution of soil or groundwater when installed. 7 Considerations related to design 7.1 Field trials 7.1.1 Test areas with various drain spacing and/or various drain types may be required as a basis for the final design of the drain installation work. 7.1.2 The process of consolidation in the test areas should be monitored by settlement measurement in combination with pore pressure measurement, preferably by means of settlement gauges and piezometers placed at various depths. The strength increase due to consolidation may be assessed by laboratory tests and/or in-situ tests. 7.1.3 When relevant, the horizontal displacements along the periphery of the test area may be measured by means of inclinometer. 7.1.4 In case of test areas with partially penetrating drains the influence on the consolidation process of underlying untreated soil layers should be taken into account. 8 Execution 8.1 Method statement 8.1.1 A method statement shall be prepared, which details the vertical drainage works. The method statement shall detail the location, drain grid/pattern, equipment and method of installation, possible restrictions during the construction phase and any hazards associated with the execution of the work. 8.1.2 The equipment and installation method chosen by the contractor shall be assessed and approved. 8.1.3 The following method statement shall be delivered as a minimum (see Clause 4): a) objective and scope of drain installation; b) site installation and working areas; c) plant and equipment;
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