The owner and designer is the Comisiòn Federal de Electricidad (Federal Comission of Electricity).

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2 Location The La Yesca Hydroelectric Project named Ing. Elías Ayub in honor of a former General Director of CFE, is part of the Santiago Hydrological System, 105 km northwest of the city of Guadalajara, within the limits of the states of Nayarit and Jalisco.

3 The owner and designer is the Comisiòn Federal de Electricidad (Federal Comission of Electricity). The construction was made by Ingenieros Civiles Asociados ICA

4 Hydrological System of the Santiago River La Yesca Proyect El Cajón Dam ( ) Aguamilpa Dam ( )

5 Layout of the Project Diversion tunnels Upstream cofferdam Concrete face rock fill dam Tailrace tunnel Downstream Cofferdam Underground powerhouse

6 Elements of the Project 1 Diversion tunnels, 2 Upstream cofferdam, 3 Downstream Cofferdam, 4 Concrete face rock fill dam, 5 Intake to Penstock, 6 Underground powerhouse, 7 Spillway, 8 Electric substation, 9 Bank of rock.

7 Q m 3 /s View diversion tunnel, february 4, 2010

8 400,000 m 3 excavation System of geological faults

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11 Unstable block - Tunnel 1 Unstable block Monolith concrete Sliding by colapso fault

12 Unstable block - Tunnel 2 Monolith concrete Sliding by colapso fault

13 Geological Model

14 Geological Model

15 Construction of a concrete monolith.

16 Cut slope Descopete Stage Elevation (m. s. n. m.) Volume of material removed (m 3 )* I to ,00 II 535 to ,00 III 520 to , IV 500 to480 80, Total ,00 Total block volume to stabilize: , ,00 = ,10 m 3

17 A 12 rotation of the longitudinal axis of the dam. As a consequence, the location of the spillway was modified. OBRA DE EXCEDENCIAS OBRA DE EXCEDENCIAS CORTINA OBRA DE GENERACIÓN TÚNELES DE DESVÍO CORTINA ATAGUÍA PREATAGUÍA ORIGINAL OBRA DE TOMA PRESENT OBRA DE TOMA

18 Structural reinforcement diversion tunnels A B A' B'

19 Shear-Column

20 Spillway

21 Main dam section La Yesca dam is m high and 12,000,000 m 3 in dam body. EL. 580,50 NAMO 575,00 NAME EL. 577,00 Alluvial processing < m, 2 NAMINO 518,00 3H 3G EL. 469,00 1,85:1 2 CONCRETE FACE 1,4:1 1B 3B T 1:1 1,4:1 3C 4 1:1 Alluvial, 3B Transition (rock sound o alluvial), T Compacted rockfill sound, 3C Rock sound >1.00 m, 4 Lags free of clay materials and weathered bedrock, maximun size >0.80 m, 3G Lags free of clay materials and weathered bedrock, maximun size >0.40 m, 3H Sandy silt, 1B EL. 409,00 EL. 375,00

22 Properties of the Dam Obtained of rockfill test (before construction) Table 1: Parameters used in La Yesca analyses (project) Material Unit weight Poisson s Ratio E c E f ϕ 0 Δϕ g d (kn/m 3 ) Ν MPa MPa degrees Degrees 3B; gravel T; rockfill C; rockfill

23 Technical achievements and advanced experience The main target was to obtain a rockfill embankment with low deformability. We used sound rocks, well-graded grain size distribution curves, with the addition of 250 lts/m 3 of water for all materials.

24 Technical achievements and advanced experience In the 3B zone, the layer thickness was alluvial material of maximum 0.8m, 1m in T zone and 1.2 m in 3C zone. We used a heavy vibratory roller compactor (12.2 t of mass in the drum); these design aspects were implemented during construction and have led ton get a good performance of the embankment.

25 Due to the lack of information about the dynamic properties of the rockfill materials: shear modulus of rigidity (G) and the critical damping ratio (λ). These parameters were estimated based on the analytical expressions reported in the literature and adjusted in terms of the experience gained in materials with similar characteristics.

26 If information is available on history cases where both the excitation and the response of some dams has been recorded. Moduli of the materials and the damping factors can be estimated by solving the inverse problem (identification of parameters). This is not reported in technical papers.

27 Technical achievements and advanced experience CROWN El END OF CONSTRUCTION FLOW SHARFT PLINT EL V-23 V-1 V-2 V V-52 CONCRETE FACE V-53 V-54 V-55 V-56 V-59 V-60 V-61 V-24 V-25 V-26 V-27 V-28 V-82 V-83 V-84 V-85 V-86 V-87 V-88 V V-4 V-5 V-6 V-7 V-8 V-9 V-10 V-11 V-12 V-13 L T2-M10 L T2-M9 L T2-M L T2-M7 V-33 V L T2-M6 L T2-M B 175 MPa T 163 MPa 3C 66 MPa L T2-M L T2-M L T2-M2 El. 409,00 L T2-M MEASURING PIN PROFILE OF ROCK SOUND IC-6 ALLUVIAL PROFILE MEASURING PIN IC-8

28 Technical achievements and advanced experience END OF CONSTRUCTION The maximum settlement was 90cm, in material 3B. Field measurements made with hydraulic levels and as well as with vertical inclinometers lead to maximum values of about 95 cm that occurred at mid height of the embankment at material T (similar to 92 cm calculated in the design stage). The peak calculated settlements in zone 3C was 90cm.

29 Technical achievements and advanced experience. The set of results covering the different zones of the dam show that the maximum measured and calculated settlements are quite similar and it can then be concluded that the construction procedure of the embankment was reasonably well modeled.

30 Technical achievements and advanced experience FIRST FILLING APRIL-2012 TO DATE The settlements measured on the dam using water levels for the period from April 3, 2012 (initial impounding) to August 15, 2013 were: 9 cm in 3Bmaterial. 11 cm in the T material. 12 cm in the 3C material. The settlement value is much lower than the estimated with the behavior model.

31 Contours of settlements (cm) determined with hydraulic levels at La Yesca Dam (august 7, 2013) for first filling Water level in the dam at September 6, Sep-12 2

32 Properties of the Dam Table 2: Static and dynamic deformation moduli measured in the field in comparison with those assumed in the project (100% E 0 ) Material (g d ) field E s (g d ) projet (100%E 0 ) Project V s E d E d / E s No. kn/m 3 MPa kn/m 3 MPa (m/s) MPa 3B T C

33 Properties of the Dam It can be observed that the values of the unit weights reached in the field using the implemented compaction procedure were in all cases higher than those adopted for design.

34 Properties of the Dam Other wise, when comparing the deformation moduli measured with the hydraulic levels with those adopted by the project, differences of about 25% are encountered. Do we need a Triaxial camera in order to know better the rockfill parameters? Do we need this for dams with 250m or 300m high, or with strong earthquakes?

35 Technical achievements and advanced experience The maximum normal displacement measured in the concrete face were 8 cm to the center of the concrete face.

36 Instrumentation installed in the concrete face Inclinometers displacement inclined face installed concrete slabs L-15, L-21 and L-30 Displacement references installed in vertical concrete face, elevation masl

37 Technical achievements and advanced experience Monitoring stabilizer works, anchor-plugs and shear-columns, has shown a good behavior of these structures to date. However, should continue its monitoring to ensure that before a special event such as earthquake or drawdown water levels (for which they were designed) have the expected performance thereby ensuring the integrity of the dam.

38 Measuring instruments installed in the shearpiers Accumulated displacement gauges installed in shear-piers

39 01-abr abr may jun jul ago sep oct nov dic ene feb mar mar abr may jun jul ago sep-13 Pruebas del Desagüe de Fondo Deformación unitaria Cierre de compuerta T-2 Filtraciones en T-1 Entrada de agua al recinto Nivel de embalse en msnm ELEVATIONS IN masl Locating electrical extensometers at anchor-plug 1 MONOLITH LAGGING MATERIAL ANCHOR PLUG L= (+) Expansión (-) Compresión Strain gauges located on the lower bed tunnel anchor-plug 1 EXTUT1-1 EXTUT1-2 EXTUT1-3 EXTUT1-4 EXTUT1-5 EXTUT1-6 EXTUT1-7 EXTUT1-8 EXTUT1-9 EXTUT1-10 EXTUT1-11 EXTUT1-12 EXTUT1-13 EXTUT1-14 EXTUT1-15 Embalse Recinto

40 The characteristics of compressibility of the materials constituting La Yesca Dam, their geometry and the compaction procedures adopted in the field have been determinant in the magnitudes of the low settlements measured during the construction process and two years after the first filling.

41 BNC-3 L1-M13 L1-M12 L1-M11 L1-M10 L1-M9 L1-M8 L1-M7 L1-M6 L1-M5 L1-M4 L1-M3 L1-M2 L1-M1 BNC-2 Asentamiento acumulado en cm BNC-3 L1-M13 L1-M12 L1-M11 L1-M10 L1-M9 L1-M8 L1-M7 L1-M6 Asentamiento acumulado e Settlements concrete -3 face -4 October 4, abr abr may jun jul nov dic ene ene feb may jun jul ago ago-13 Pr -5-6 Asentam El J 04-abr abr may jun jul ago sep oct nov dic ene ene feb feb mar abr may jun jul ago ago sep sep oct-13 Proyecto Hidroeléctrico La Yesca, Jal.

42 01-abr abr abr may may jun jun jul jul ago ago sep sep sep oct oct nov nov dic dic ene ene feb feb mar mar mar abr abr may may jun jun jul jul ago ago sep sep sep oct-13 Asentamiento acumulado en cm 01-abr abr abr may may jun jun jul jul ago ago sep sep sep oct oct nov nov dic dic ene ene feb feb mar mar mar abr abr may may jun jun jul jul ago ago sep sep sep oct-13 Asentamiento acumulado en cm Settlements Trend vs time, Topographical references, Face Rock-Fill. Transversal Line LT1 October 3, 2013 BNC-3 LT1-M1 LT1-M2 LT1-M3 PBC-5 LT1-M4 LT1-M5 PBC-4 LT1-M6 IC-5 PB-IC5 LT1-M7 LT1-M8 LT1-M9 PBC-3 LT1-M10 LT1-M11 Proyecto Hidroeléctrico La Yesca, Jal. Tendencia de Asentamientos vs Tiempo en referencias topográficas de cortina, Cara Enrocamiento Línea Transversal LT1 Elaboró: JASM Instrumento utilizado: Revisó: MMH Nivel automático NAK-2 Fecha de Elaboración: 03-oct-13 BNC-3 LT1-M1 LT1-M2 LT1-M3 PBC-5 LT1-M4 LT1-M5 PBC-4 LT1-M6 IC-5 PB-IC5 LT1-M7 LT1-M8 LT1-M9 PBC-3 LT1-M10 LT1-M11 Proyecto Hidroeléctrico La Yesca, Jal.

43 Water level reservoir Precipitation and spending leak By the desplacement of the longitudinal axis of the dam, the galeries lekage 320 l/s The body of the dam, has a lekage of 220 l/s

44 LEAK PHENOMENON From November 2012 to end of July 2013 the water level fluctuated between elevations 530 and 540 m. During this time, the leaks in the gallery at the bottom of the dam and drainage galleries were maintained with relatively small discharge; total discharge of the almost 80 l/s.

45 The lack of coverage and quality of the rock in this area could explain the fact that when the reservoir reached elevation 540 m, appeared on the gallery covering GD-2, near tympanum, two fissures. These contributed significant leaks in the order 45 l/s. As a remedial measure, a concrete plugs 30 m long was constructed, leaving a length of 15 m accessible for injections seal from the inside.

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47 STUDIES OF LEAKS AND MONITORING Leakage monitoring is carried out on both sides of the dam. The leaks of the various branches of the injection and drainage galleries, of the slopes and the powerhouse are measured separately, in order to identify their origin and thus identify the areas of greatest contribution. Seepage of the body dam is captured in the gallery at the bottom and measured continuously in an outer triangular spillway.

48 It is relevant in the evolution of the leaks, that during emptying at equal elevations, the discharges recorded at the bottom of the dam and in right margin galleries are higher than those recorded during the first filling. This may be associated with an unblocking of important waterways, due to washing of fine material from some discontinuities of the massif

49 FIELD WORK AND REMEDIAL MEASURES From the reservoir, brine tests were performed to verify whether there were preferential flows to the galleries of right bank or to the filtrations gallery. Residues of brine were detected in the Gallery GD-2 and the leaks registered at the foot of the dam. This fact revealed a communication directly between the reservoir at the elevation 490, and the embankment of the dam.

50 Reinforcement sealing plane through the galleries injection and drainage. a) Longitudinal section; b) Cross Section.

51 The dam and the concrete face shows an excellent behaviour up to now, with less than 20 cm of maximum settlement in the rockfill embankment during two years under operation. The instruments in the concrete face joints have less than 15 mm in opening or settlement as result of the good rockfill behaviour. The phenomenon of leaks that has taken place on the dam and drainage galleries of grouting and after the filling of the reservoir has been controlled almost entirely by implementing of a series of fieldwork, some already executed and others are going to execute.

52 It has been defined very precisely the area of strong contributions and have implemented the necessary corrective measures. To date (November 2014), with an elevation reservoir of m (17m above the NAMO); however, is necessary to ensure that in future such leaks will remain at acceptable values for the project.

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54 CONCLUSSION FOR US, ONE OF THE MAIN CONCLUSSION IS THAT CONCRETE FACE ROCKFILL DAMS MUST BE HOMOGENUSLY COMPACTED, ALL THE MATERIALS.

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