4 Information needed for the execution of the work

4.1 General

4.1.1 Prior to the execution of the work, all necessary information shall be provided.

4.1.2 This information should include:

  • a) any legal or statutory restrictions;
  • b) the location of main grid lines for setting out;
  • c) the conditions of structures, roads, services, etc. adjacent to the work;
  • d) a suitable quality management system, including supervision, monitoring and testing.

4.1.3 The information regarding the site conditions shall cover, where relevant:

  • a) the geometry of the site (boundary conditions, topography, access, slopes, headroom restrictions etc);
  • b) the existing underground structures, services, known contamination, and archaeological constraints;
  • c) the environmental restrictions, including noise, vibration, pollution;
  • d) future or ongoing construction activities, such as dewatering, tunnelling, deep excavations.

4.2 Particular requirements

4.2.1 The following information shall also be provided:

  • a) previous experience of deep mixing or special geotechnical works adjacent to the site, including the results of field tests to confirm the design;
  • b) underground contamination or hazards that can affect the execution method, the work safety or the discharge of excavation material from the site.

4.2.2 The following instructions shall be given:

  • a) reporting procedure for unforeseen circumstances, or conditions revealed that appear to be different from those assumed in the design;
  • b) reporting procedure, if an observational method of design is adopted;
  • c) notice of any restrictions such as construction phasing required in the design;
  • d) a schedule of any testing and acceptance procedures for materials incorporated in the works.

4.2.3 Any additional or deviating requirements falling within the permission clauses given in this document shall be established and agreed upon before the commencement of the works.

5 Geotechnical investigation

5.1 General

5.1.1 The depth and the extent of any investigations shall be sufficient to allow determination of the ground conditions in accordance with the requirements of EN 1997-1.

5.1.2 Laboratory and field investigations shall comply with prEN 1997-2 and the relevant European Standard EN 196-1 to -8, EN 196-21, EN 197-1 and -2, EN 451, EN 459-1 and -2, ENV 10080, EN 12716, EN 791, EN ISO 14688-1 and EN ISO 14688-2 .

5.1.3 Relevant experience of the execution of comparable deep mixing works under similar conditions in the vicinity of the site shall be taken into account when determining the extent of the site investigation.

5.1.4 The site investigation report shall be made available together with all relevant data known to affect the choice of method.

5.1.5 Boreholes or trial pits shall be suitably sealed not to affect groundwater movement and/or subsequent deep-mixed column construction and performance.

5.2 Specific information

5.2.1 Identification and classification of soil shall comply with EN ISO 14688-1 and EN ISO 14688-2.

5.2.2 Apart from the general geological description and the details listed in EN 1997-1, the site investigation report shall contain the following information regarding ground conditions for the execution of deep mixing:

  • a) the composition, lateral extent, thickness and firmness of the surface stratum, tree roots, fill, etc.;
  • b) presence of cobbles or boulders, cemented layers or underlying rock that can cause difficulties for the execution or could require special methods or tools;
  • c) presence of swelling soil (montmorillonite);
  • d) cavities, voids or fissures;
  • e) piezometric levels of groundwater, its variation and possible artesian pressure;

5.2.3 When relevant, the following additional information should be provided: Physical and state characteristics:

  • a) consistency limits;
  • b) classification;
  • c) density;
  • d) grain size distribution;
  • e) mineralogy;
  • f) natural water content;
  • g) organic content. Mechanical characteristics:

  • a) deformation and consolidation;
  • b) strength (shear, compressive and tensile);
  • c) permeability. Environmental, chemical and biological characteristics:

  • a) groundwater quality (e.g. contamination, aggressiveness, chemistry, pH- value, type and concentration of ions and metals (reference measurements);
  • b) contamination test data;
  • c) leaching tests.

5.2.4 The ground level and location at any point of investigation or testing should be established relative to the recognised national datum or to a fixed reference point.

6 Materials and products

6.1 General

6.1.1 Construction of deep mixing involves the addition of a binder and, if needed, one or more of the following components to the soil:

  • a) admixture;
  • b) water;
  • c) filler;
  • d) structural reinforcement.

6.1.2 All materials and products for incorporation in deep mixing shall be in accordance with the relevant European Standards. Where the respective European Standards are not available, the use of materials and products shall be in accordance with the national standards and/or guidance.

6.1.3 All materials and products used shall comply with local environmental regulations.

6.1.4 All materials and products used shall comply with the design specifications.

6.1.5 Appropriate tests shall be provided in order to ensure compliance with the design specifications for materials not covered by existing standards.

6.1.6 The sources of supply materials shall be documented and shall not be changed without prior notification.

6.2 Special considerations

6.2.1 Water from other sources than recognised potable water shall be tested to determine whether or not it is suitable for the intended use.

6.2.2 Environmentally significant traces of chemical substances in materials and products may be present as normally occurring impurity, and their environmental impact may need to be assessed.

EN 14679:2005 Execution of special geotechnical works — Deep mixing