Seite - 1023 - in Book of Full Papers - Symposium Hydro Engineering

  )GPa()tt)(05.0t(2.31 0.40 1 )t,t(J 112.00 35.0 00       [1] which is represented in Fig. 2 for three ages of loading, as well as the corresponding relaxation curves obtained through numerical inversion. Mention must be made to the fact that the concrete presents low creep rates for high loading ages. Fig. 2 Creep and relaxation curves of the dominant dam’s concrete 2.4. MONITORING SYSTEM The dam monitoring system allows the evaluation of the actions and the determination of the thermal, structural and hydraulic responses [4], by measuring (in brackets the total number of measurement instruments are indicated): i) the upstream and downstream levels, by staff gauges and water level recorders; ii) air temperatures, in an automatic weather station; iii) uplifts, by means of a piezometer network (41) installed in the drainage gallery; iv) horizontal displacements, by coordimeter bases installed at the intersection of the 5 plumb lines with the inspection galleries; v) horizontal displacements by 3 traverses on galleries; vi) vertical displacements, by precision geometric levelling on the crest and on 4 galleries; vii) vertical and horizontal displacements of the rock mass foundation, by rod extensometers (16) installed also in the drainage gallery; viii) joint movements, using electrical resistance devices for measuring the movement of joints (152) and three-dimensional baselines (103); ix) temperatures in the dam’s body, by electrical resistance thermometers (52), by devices for measuring the movement of joints, by strain meters and stress meters; x) strains, by groups of one, five or nine Carlson strain meters (265); xi) stress, by stress meters (10); xii) water pressures in the concrete, by pressure cells (6); and xiii) discharged and infiltrated flows, by foundation drains (216) and measuring weirs (18). The dam is also equipped with 3 creep cells, for evaluation of the concrete deformability over time, a GNSS system to measure displacements (4 antennas, 1 reference station and 3 stations on the crest), a seismic monitoring system (6 triaxial accelerometers, 3 near the foundation and 3 on the upper central zone) and a dynamic response monitoring system (20 accelerometers installed on the upper galleries). 1/E CREEP RELAXATION t = 1000 days t = 10000 days t (years)402010 30 50 t = 100 days0 0 0 R(t,t ) 0 E(t ) 0 E0 t (years)402010 30 50 t = 10000 days0 t = 1000 days0 t = 100 days0 0 J(t,t ) 0 E(t ) 0 1 E = 40.0 GPa0 E = 40.0 GPa0 1023