PERFORMANCE OF SCHLEGEIS ARCH DAM

摘要

The Schlegeis Arch Dam was designed as double-curvature arch-gravity dam in a wide valley. The design and safety analyses were carried out with linear numerical models based on the trial load method. As it is shown by measurements, the linear analysis provides an appropriate representation of the overall bearing behavior of the structure. However, during the first filling of the reservoir unexpected high seepage into the bottom gallery - located at the rock surface - was monitored. This was explained by local deformations at the dam's upstream heel. The construction of an elastic cut off wall solved the seepage problem. To find an appropriate numerical model for the interpretation of measured data and for reassessment of the structural safety and integrity - considering this local phenomena - a detailed finite element model was developed. The linear analysis results show tensile stresses at the upstream heel of the dam. Paying attention to the geological site condition, the model was updated with an entire perimetral base joint at the abutment, to allow the separation of the darn from the rock. The results show a significant opening of the base joint. Especially at the highest concrete block the base joint opens to an extent of about 50 % over the entire thickness. This behavior is accompanied by a stress redistribution in the dam body itself and increases the inclined abutment forces. The arch dam bearing behavior enables a safe redistribution of stresses. This model behavior together with a careful interpretation of the measurement readings are the basis for the structural safety assessment.