Supervision monitoring and maintenance

Eurocode 7 has specific requirements to ensure the quality and safety of a structure:

... the construction processes and workmanship shall be supervised; the performance of the structure shall be monitored during and after construction; [and] the structure shall be adequately maintained.

EN 1997-1 qualifies this requirement by saying these tasks should be undertaken 'as appropriate'. Thus, if construction does not need supervising, or the structure does not need monitoring or maintaining, then the design could explicitly rule out the need for them.

Figure 3.7. Overview of supervision, monitoring, and maintenance

Figure 3.7 gives an overview of the activities that are specified by Eurocode 7 as part of its supervision, monitoring, and maintenance requirements. They include supervision of the construction process and workmanship, monitoring the performance of the structure, checking ground conditions, checking construction, and maintenance.

3.7.1 Supervision

Figure 3.8 overleaf shows a detail from Figure 3.7, dealing with the supervision and checking requirements only. Certain activities are required for structures in particular Geotechnical Categories only - these are indicated by the numbers on the diagram. (On this diagram, GDR = Geotechnical Design Report, as discussed in Chapter 16.)

Supervision involves checking design assumptions are valid, identifying differences between actual and assumed ground conditions, and checking construction is carried out according to the design. A plan of supervision should be prepared, stating acceptable limits for any results obtained, and indicating the type, quality, and frequency of supervision.

The amount and degree of inspection and control and the checking of ground conditions and construction all depend on the Geotechnical Category (GC) in which the structure is placed (see Section 3.2.3). If an alternative method of assessing geotechnical risk is used, then the amount of inspection and control should be selected appropriately for the risk involved. The fact that EN 1997-1 relates its requirements for supervision to the Geotechnical Categories may make their adoption difficult to avoid.

3.7.2 Monitoring

Figure 3.9 shows another detail from Figure 3.7, covering the monitoring of the structure's performance during and after construction.

Monitoring involves measurements of ground deformations, actions, contact pressures, and such like and an evaluation of the performance of the structure. For structures placed in Geotechnical Category 1, such evaluation is simple, qualitative and based largely on inspection. For Category 2 structures, the movement of selected points on the structure should be measured. Finally, for Category 3 structures, monitoring also involves analysis of the construction sequence. If an alternative method of assessing geotechnical risk is used, then the degree of monitoring should be selected appropriately for the risk involved.

checking validity identifying differences between actual ground conditions and those assumed checking construction is carried out according to design states acceptable limits for results obtained type quality frequency hi inspection simple quality controls qualitative assessment

1 of performance measurements of ^ ground properties measurements of '•JÎ structural behaviour additional measurements 3.' during each significant stage plan of supervision •

Checking ground conditions

Supervision of construction, monitoring, and maintenance

Supervision of construction processes and workmanship inspection and control -

records kept for 10 years careful review ground conditions groundwater conditions actions of the structure environmental impacts and changes

Checking construction inspect the site determine types within zone

V of influence of structures record descriptions in excavations ■■29 check geotechnical properties if additional site investigation may be needed recover samples for testing index properties, & strength, and deformability

I3.'1 further investigations ^ «!'' detailed examination of ground or fill checks based on previously il^ documented experience

V indirect evidence direct observations

& direct observations /

if they greatly affect construction method or structural performance construction sequence decided by contractor

- L1 GDR may not include formal construction schedule

- ^ GDR may give construction sequence

- 3 gdr may give construction sequence

construction sequence may be decided by contractor

-groundwater assessment of the design including landslides and rockfalls

Figure 3.8. Supervision of construction process and workmanship

Figure 3.9. Monitoring the performance of the structure

3.7.3 Maintenance

Maintenance of a structure ensures its safety and serviceability and the requirements for it should be specified to the owner or client. These requirements include identifying those parts of the structure that require regular inspection, warning about work that should not be undertaken without prior design review, and indicating the frequency of inspection.

3.7.4 Practical recommendations

Although EN 1997-1 imposes specific requirements for supervision, monitoring, and maintenance, it gives few practical recommendations as to the actions that need to be taken to meet those requirements.

This is demonstrated by the small number of paragraphs on this subject in the whole of Part 1 (thirty-three), broken down as follows: §5 Fill, de-watering, etc., eight paragraphs; §6 Spread foundations, two; §7 Pile foundations, eight; §8 Anchorages, eight; §9 Retaining structures, none; §11 Overall stability, two; and §12 Embankments, five. The table below summarizes the information given in §4 of EN 1997-1 with regards to supervision, monitoring, and maintenance.

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