Tham khảo tài liệu 'nuclear power operation safety and environment part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Geodetic Terrestrial Observations for the Determination of the Stability in the Krsko Nuclear Power Plant Region 79 Fig. 1. Stabilisation and signalisation of the reference and control points The Libna network The measuring points were determined by a set of two physically stabilised points. The measuring points onto which the reflector was forced-centred presented the points monitored for displacements. In all measurement epochs we used the same reflectors - Kern ME 5000. All the measurements were carried out on the points that were - according to the reference measuring points - set up ex-centrally. The term ex-central stand was introduced. The distance from the ex-centre to the centre point was 10 - 20 m Figure 2 . The reference points were stabilised by combining the methods described above Figure 3 . However the implementation was simplified and the costs were lower. A mass-produced concrete tube with 0 m in diameter and 1 m length was used. A hole of the same diameter was drilled into the pillar and a concrete tube was put into the hole. The tube was filled in with concrete and a device for forced-centring was built in. The cylinder top was covered with a mass-produced cover for full protection. Fig. 2. Ground stabilisation of the centre and the ex-central stand 80 Nuclear Power - Operation Safety and Environment Fig. 3. Signalisation of the centre and the ex-central stand The instrument stand was stabilised with the usual ground stabilisation by means of a concrete square stone with a built-in plug. Above the instrument stand a tripod was set-up centred and levelled. The centring accuracy did not influence the end results since the coordinates of the measuring point onto which the reflector was forced-centred were of crucial importance not the co-ordinates of the instrument stand. However the tripod s stability during the measurements was essential. The procedure of ensuring the appropriate network geometry and required precision for the .
