6 Materials and products

6.1 General

6.1.1 A soil nail construction can involve the following material components for:

  • a) soil nail system;
  • b) facing system;
  • c) drainage system.

6.1.2 All requirements on materials and products shall be specified in advance for the works, based on a European or a National standard. Where no appropriate European or National standard exists, its application shall comply with the manufacturer's recommendations and with the relevant acceptance certification. The compliance with the specified requirements shall be documented during execution.

6.1.3 All requirements on materials shall be specified in advance. The compliance with the specified requirements shall be documented during execution.

6.1.4 Materials and products used in the soil nail, the facing and the drainage systems shall be mutually compatible.

6.1.5 Material and products shall exhibit the properties necessary to ensure that they satisfy the design life of the structure and that the serviceability limits are not exceeded.

6.1.6 Newly developed materials may be used, provided that the performance of the system and durability of the materials have been proven.

6.2 Soil nails systems

6.2.1 General

Soil nail systems are produced using a wide range of materials and configurations. The following subclauses describe the main components that may be required to produce a soil nail system. Examples of soil nail systems are given in Annex A.

6.2.2 Reinforcing element General The reinforcing element of the nail is usually produced from metals (typically steel) and to a lesser extent from other materials, such as fibre reinforced plastics, geo-synthetics or carbon fibre.

NOTE The reinforcing element may be a solid bar, a hollow bar, an angle bar or some other form of cross-section. When nails are to be grouted, they may be ribbed or profiled to improve the effective bond with the grout. All reinforcing elements shall exhibit the stress/strain properties, durability and soil-reinforcement interaction properties required by the design. Metallic reinforcing element All metallic reinforcement used shall conform to 6.1.2 in particular (no entire enumeration):

  • a) a metallic reinforcement needs an elongation (Agt) of at least 5 % at failure;
  • b) a solid steel bar, used as a reinforcing element, shall conform to EN 10080;
  • c) a hollow steel bar, used as a reinforcing element, shall conform to EN 10210 (all parts) or EN 10219 (all parts);
  • d) a hot rolled steel product, used as a reinforcing element, shall conform to EN 10025-2;
  • e) pre-stressed steel products, used as a reinforcing element, shall conform to EN 10138 (all parts). The reinforcing element shall have a minimum thickness, which guarantees its mechanical behaviour during the entire design life. When using a steel reinforcement element, consideration should be taken to design life due to corrosion, see Annex B. Coatings and compounds for corrosion protection shall comply with the design specifications. The continuity of the protection, close to the connection elements shall comply with the design specifications. The corrosion protection of high strength steel and pre-stressing steel shall be in accordance with EN 1537.

NOTE The steel can be classified as high-strength steel if it has fy > 600 MPa and if no other information is available. If a steel reinforcing element is galvanised, the hot dip galvanised coating shall comply with the requirements of EN ISO 1461. Non-metallic reinforcing element Other materials may be used as a soil nail reinforcing element provided they comply with 6.1.2. Other materials used shall have ductile behaviour. Joints and couplings Joints and couplings can govern the strength of the soil nail system. The corrosion protection of the coupler shall be compatible with the protection of the reinforcement element.

6.2.3 Grout Cementitious or non-cementitious grouts shall be compatible with the reinforcing element. If cement grout is used as a part of a soil nail system, then the cement shall conform to EN 197-1 and the provisions of this standard.

NOTE The selection of the type of cement for the grout should consider the aggressiveness of the environment, the permeability of the ground and the design life of the nail. The aggressiveness of the environment may be determined in accordance with EN 206-1. Water/cement ratios (weight-ratio) should be appropriate to the ground conditions, nail system construction method, durability and strength requirements.

NOTE A typical maximum value is 0,55. Admixtures may be used for improving workability, durability, reducing bleed, reducing shrinkage or adjusting rate of setting and strength development. Admixtures should not contain any product liable to damage the reinforcing element or the grout itself. Admixtures that contain more than 0,1 % by mass of chlorides, sulphates or nitrates should not be used. Inert fillers may be incorporated within the grout, for example the introduction of sand or an acceptable proportion of known drilling spoil, provided the agreed specifications are met. Typically, grout should achieve a minimum characteristic strength of 5 MPa prior to load being induced in the soil nail, and the 28 days characteristic strength of the grout mix should not be less than 25 MPa.

6.2.4 Sheaths and ducts

Where used, sheaths and ducts shall not compromise the load transfer between the reinforcing element and the ground.

EN 14490:2010 Execution of special geotechnical works – Soil nailing