Issue 35

S. Valente et alii, Frattura ed Integrità Strutturale, 35 (2016) 306-312; DOI: 10.3221/IGF-ESIS.35.35 310 The hydro-mechanical coupling hypothesis Fig.1 shows the assumed distribution of uplift pressure in the case of complete drain efficiency. The pressure is assumed constant up to the point where the crack opening displacement is larger than a threshold value of 1.e-6 m. Elsewhere the pressure is a linear function of the position, vanishing at the downstream edge. R ESULTS ig. 5 show the results at the end of the local stage when the distance of the FCT from the upstream edge is 7.2 m. The circular symbol shows the crack opening displacement (shortened COD). Similarly, the square symbol shows the crack sliding displacement (shortened CSD). The rhomb symbol shows the contact pressures and the triangular symbol shows the tangential stresses. Both stress components are divided by 1 MPa. Similarly, Figs. 6, 7, 8, 9 and 10 refer to a distance respectively of 12, 18, 24, 30 and 36 m. It is possible to observe that the method is able to manage three different regimes: (a) in Fig. 5 the FPZ is not completely developed, (b) in Figs. 6, 7, 8, 9 the point where the tangential cohesive stress vanishes is open (COD > 0), (c) in Figs.10 the point where the tangential cohesive stress vanishes is closed (pressure >0). Figure 5 : Results for the first step of the global stage. COD and CSD are divided by 0.8 mm. The load level is 70% of full reservoir. Figure 6 : Results for the second step of the global stage. COD and CSD are divided by 1.4 mm The load level is 80% of full reservoir. Figure 7 : Results for the third step of the global stage. COD and CSD are divided by 2.1 mm. The load level is 94.96% of full reservoir. Figure 8 : Results for the 4-th step of the global stage. COD and CSD are divided by 2.7 mm. The water level is 0.28 m above the dam crest. F