Monitoring of Concrete Face Rock fill Dam

Abstract

The Shahr-e-Bijar dam is a 96.5 m high and 430 m long concrete faced rock-fill dam with reservoir volume of 105 million m3. Construction of the dam was completed in April 2014. Throughout the dam construction, comprehensive monitoring had been carried out to verify the dam behavior so that stability and safety of the dam were ensured. Monitoring of the dam be- havior was based on the measurement data of instruments which installed in the dam body and the foundation as well as daily visual inspection. In this study, a two dimensional finite element analysis of SEB dam is carried out and the computed displacements and internal stresses compared with those measured in situ by the instrumentation. The rock-fill material is represented by the hardening soil model which is a modified version of Duncan and Changs hyperbolic model. The maxi- mum recorded construction settlement is around 0.80 m at the maximum cross section and around 0.50 m at the sections on the abutments which correspond to 0.9% of the dam height. The deformations will further increase with first impounding and rising reservoir to full supply level and due to creeping of the rock-fill. The results of different instruments which are used for the settlement monitoring of the dam are shown that the accuracy of hydrostatic settlement cells is more than other in- struments and the measured settlements by the magnetic plates around the inclinometers tubes are usual below the actual settlement. The stress arching within the dam body and abutments is recorded as 50 % in the middle of dam body and 60 % in the near of the banks. Also, during the construction, the shrinkage is mobilized within the dam body along the axis of dam at the first stage of construction and then by increasing the overburdens height, the expansion is recorded and increased up to the end of construction. The results are shown 65 mm as the maximum expansion which is mobilized at the middle part of the dam body.