9 Supervision, testing and monitoring

9.1 Supervision

9.1.1 A suitably qualified and experienced person shall be in charge of the supervision of the work.

9.1.2 A schedule for the supervision should be available at the construction site. In this schedule as a minimum the following shall be noted:

  • frequency of the different checks;
  • content of the different checks.

9.1.3 The supervision of works connected with the execution of micropiles shall be in accordance with section 4 of EN 1997–1:2004.

9.1.4 As a minimum the supervision shall include:

  • the conformity of the works with this document and with any additional specification and agreed working procedure;
  • the monitoring of micropile execution in accordance with 9.2.

9.2 Monitoring of micropile construction

9.2.1 The specific procedures for verification, control and acceptance shall be established before the commencement of the works.

9.2.2 The micropile construction process shall be monitored and all relevant data according to Tables 1 to 3 shall be recorded.

9.2.3 The duration of the respective operations should also be recorded.

9.2.4 All non conformances shall be notified.

9.2.5 During installation, the ground behaviour shall be observed and any unforeseen change or feature that might be important for micropile quality shall be considered and where relevant appropriate measures shall be taken.

9.2.6 After construction of the micropiles, an "as built" record shall be drawn up showing positions and dimensions of micropiles together with their head and founding levels.

9.2.7 The record plan, the micropile monitoring records and any other construction documentation shall be kept to the files as required by the contract and/or the statutory requirements.

9.3 Micropile testing

9.3.1 General Tests on micropiles can be performed on preliminary micropiles and/or working micropiles. The principal requirements for micropile load testing are contained in EN 1997–1.

NOTE It is expected that in future a separate EN will contain appropriate provisions for testing procedures.

9.3.2 Static load tests General Static load tests on micropiles may consist of:

  • a) maintained load tests;
  • b) constant rate of penetration tests. When the loading procedure of static load tests as defined in not specified, it shall be done in accordance with of EN 1997–1:2004.

NOTE 1 Micropiles with steel bearing elements which transfer a compression load to the ground by skin friction may be submitted to a tension load test in agreement with the Client's Technical Representative. The number of load tests follows

NOTE 2 Micropiles with steel bearing elements which transfer their load to the ground by skin friction may be tested according to EN 1537. Static load tests on preliminary micropiles Static load tests on preliminary micropiles shall be performed when:

  • a) new techniques are used for the execution of the micropiles;
  • b) micropiles have to be installed in ground conditions for which previous tests are not available;
  • c) higher working loads are applied than those already adopted in similar ground conditions;
  • d) when the results of static load tests are used to determine the design load. When static load tests are performed on preliminary micropiles at least two micropiles should be tested. When choosing the location of preliminary micropiles, due consideration shall be given to ground conditions. Static load tests on working micropiles In the project specifications it shall be specified if static load tests have to be performed on working micropiles. Unless otherwise specified, for micropiles working in compression static load tests on at least two micropiles should be performed for the first 100 micropiles and 1 for each next 100 micropiles. Unless otherwise specified for micropiles working in tension static load tests on at least two micropiles should be performed for the first 25 micropiles and 1 for each next 25 micropiles. Loading procedure The loading procedure should be in accordance with of ENV 1997–1:2004. For static load tests on working micropiles the maximum proof load must not jeopardize its serviceability. The transverse displacements of the micropile head should also be measured during the test.

9.3.3 Dynamic load tests and integrity tests

NOTE The use of dynamic load tests and integrity tests can not be generalised for micropiles because the interpretation of the results concerning the bearing capacity and integrity may be difficult due to the small diameter and/or shape of the micropile and the presence of a bearing element. So the use of dynamic load tests and integrity tests has to be limited to cases where experience or comparison with static load tests has demonstrated that the results can be interpretated in a confident way. For dynamic load tests the micropile shall be allowed to gain sufficient strength after installation and before testing. Dynamic and integrity tests shall be carried out using equipment built and approved for the purpose and are required to be interpreted by persons competent in this area who shall also have a knowledge of the techniques of piling and experience of the specific ground conditions. The apparatus shall be used in accordance with the manufacturer's instructions and the micropile shall be prepared for the purpose of testing in an appropriate manner.

EN 14199:2005 Execution of special geotechnical works — Micropiles