9 Supervision, testing and monitoring

9.1 General

9.1.1 Supervision, monitoring and tests shall be performed by qualified and experienced persons and comply with EN 1997-1, specifications based on the design and other specified requirements.

9.1.2 Any deviations from the expected situation or ground conditions or any cases of non-conformity shall be reported immediately as stated in Clause 4.

9.1.3 All necessary information concerning the works shall be recorded (see Clause 10).

9.1.4 An assessment of the results of nail tests shall be made before the beginning or continuation of the nail installation.

9.2 Supervision

9.2.1 The level of supervision (type, extent, accuracy, monitoring and testing) shall take into account the contents of this clause and shall be clearly established and defined before work commences.

9.2.2 Records of the construction works shall be made in accordance with Clause 10.

9.2.3 Particular quality control checks (performed according to technical specification) can include:

  • a) visual inspection of the excavated material to confirm that it is in accordance with the ground conditions considered in the design;
  • b) visual inspection of the drill spoil to confirm that it is in accordance with the ground conditions considered in the design;
  • c) assessment of conformity of the ground (type, thickness, fractured zones, etc.) and its hydro-geological nature (sources of water, seeps or oozing, etc.) with the geotechnical data assumed for the design;
  • d) monitoring for the duration of operations;
  • e) ensuring the maximum excavation height is not exceeded;
  • f) minimum time allowance between successive excavation phases to achieve sufficient strength of nail grout;
  • g) the nail orientation, bore-hole diameter, spacing and length;
  • h) the bore hole is clean and has not collapsed (if applicable);
  • i) the integrity of the corrosion protection system;
  • j) where used, grouting technique, installation of reinforcing element, mesh and sprayed concrete or geotextile/establishment of vegetation;
  • k) where required, installations of drainage system(s); it is essential that hydraulic continuity of the vertical drains is assured if installed incrementally;
  • l) placement of the bearing plate, avoiding any unacceptable deviation of placement by using tapered washers below the nut;
  • m) connection between reinforcement and facing;
  • n) verification of the material delivered at the site being in accordance with the design requirements;
  • o) function of centralisers or spacers;
  • p) quality of grout.

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