Development of an expert system for the interpretation of displacement monitoring data

Abstract

Displacement monitoring has been common practice during tunnel excavation for many decades. The results are usually used to assess the stabilisation process and to adapt excavation and support to the actual conditions. Although monitoring is done routinely on practically all sites, no consistent collection of case histories has yet been established, so the experience gained on completed projects is rarely available for new projects. To better utilise this previous experience, an expert system for the evaluation and interpretation of displacement monitoring data is currently under development. The main component of the system is an expert knowledge base containing normal displacement behaviour for a wide range of geotechnical conditions. Methods required for the identification of such normal displacement situations as well as for clear description of the displacement characteristics have been developed and will be outlined. The check whether the actually observed displacements are normal will be done by means of a comparison with a real displacement scenario from the database. In case a significant deviation is identified, the actual displacement trends will be compared to reference trends characteristic for changing ground conditions and the most probable situation determined. If the degree of correlation is low, then it is very probable that the actual displacements show abnormal behaviour.

Future Evaluation of Displacement Data in Tunnelling / Zukünftige Auswertung von Verschiebungsmessdaten im Tunnelbau

“…2). -Evaluation of the radial td rad and tangential td tang displacement tendency for each monitoring epoch t by means of the previously determined areas and according to equations (1) and (2) (1)…”

Development of an expert system for the interpretation of displacement monitoring data

“…In addition, a considerable number of numerical simulations was carried out to identify the influence of ground structure and stresses on the development of the characteristic displacement. In order to be able to compare the observed behaviours with the reference cases stored in the database, data have to be processed and stored in a specific way [7]. Methods were developed to allow easy description of characteristic behaviour.…”

“…Methods were developed to allow easy description of characteristic behaviour. Figure 1 shows the basic evaluation process of a monitoring section utilising the expert knowledge base [7]. The process starts with the input of the geological/geotechnical conditions of the monitoring section at hand.…”

“…The procedure for the tangential displacements and the displacement vector orientation is basically done in the same way. Details are given in [7].…”