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.

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The final design of the pumped-storage project Feldsee features a complex lining and pre-stress grouting concept, rendering the method presented by Seeber insufficient for an accurate determination of the system behaviour in all stages of construction and operation. A calculation procedure based on the matrix stiffness method has been implemented, allowing incorporation of multistage pre-stressing injections at different locations of a lining being composed of several layers with different mechanical properties. Based on the design obtained by applying the above method, another question of maximum allowable non-symmetric displacement of the pre-cast concrete segment arose. A parametric study has been used to determine the boundaries of asymmetric displacements throughout the pre-stressing procedure, allowing establishment of threshold values for the monitoring conducted during the pre-stressing injections. Fortschrittliche Bemessungsverfahren für vorgespannte

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