4.4 Checking construction
(1)P Site operations shall be checked for compliance with the method of construction assumed in the design and stated in the Geotechnical Design Report. Observed differences between the design assumptions and the site operations shall be reported without delay.
(2)P Deviations from the methods of construction assumed in the design and stated in the Geotechnical Design Report shall be explicitly and rationally considered and implemented.
(3)P The principles followed in design shall be checked to ensure that they are appropriate for the sequence of construction operations, which are used.
(4) For Geotechnical Category 1, a formal construction schedule need not normally be included in the Geotechnical Design Report.
NOTE The sequence of construction operations is normally decided by the contractor.
(5) For Geotechnical Categories 2 and 3, the Geotechnical Design Report may give the sequence of construction operations envisaged in the design.
NOTE Alternatively, the Geotechnical Design Report can state that the sequence of construction is to be decided by the contractor.
(1)P Monitoring shall be applied:
- to check the validity of predictions of performance made during the design;
- to ensure that the structure will continue to perform as required after completion.
(2)P The monitoring programme shall be carried out in accordance with the Geotechnical Design Report (see 2.8 (3)).
(3) Records of the actual performance of structures should be made in order to collect databases of comparable experience.
(4) Monitoring should include measurement of the following:
- deformations of the ground affected by the structure;
- values of actions;
- values of contact pressure between ground and structure;
- pore-water pressures;
- forces and displacements (vertical or horizontal movements, rotations or distortions) in structural members.
(5) Results of measurements should be integrated with qualitative observations including architectural appearance.
(6) The length of any post-construction monitoring period should be altered as a result of observations made during construction. For structures that may impact unfavourably on appreciable parts of the surrounding physical environment, or for which failure may involve abnormal risks to property or life, monitoring should be required for more than ten years after construction is complete, or throughout the life of the structure.
(7)P The results obtained from monitoring shall always be evaluated and interpreted and this shall normally be done in a quantitative manner.
(8) For Geotechnical Category 1, the evaluation of performance may be simple, qualitative and based on inspection.
(9) For Geotechnical Category 2, the evaluation of performance may be based on measurements of movements of selected points on the structure.
(10) For Geotechnical Category 3, the evaluation of performance should normally be based on the measurement of displacements and analyses, which take account of the sequence of construction operations.
(11)P For structures that may have an adverse effect on ground or ground-water conditions, the possibility of leakage or of alterations to the pattern of ground-water flow, especially when fine grained soils are involved, shall be taken into account when planning the monitoring programme.
(12) Examples of this type of structure are:
- water retaining structures;
- structures intended to control seepage;
- large underground structures;
- deep basements;
- slopes and earth retaining structures;
- ground improvements.
(1)P The maintenance required to ensure the safety and serviceability of the structure shall be specified.
NOTE Normally this is specified to the owner/client.
(2) The maintenance specifications should provide information on:
- critical parts of the structure, which require regular inspection;
- works prohibited without a design review of the structure prior to their execution;
- frequency of the inspection.