3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING

3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 Chinese National Committee on Large Dams China Society for Hydropower Engineering JOINTS : Brazilian Committee on Large Dams International Hydropower Association International Society for Soil Mech. and Geotec. Engineering PERIMETER JOINT IN AN ASYMMETRIC NARROW CANYON AT RIVERBED AREAS – MAZAR CFRD (ECUADOR)’ CASE Manoel S. Freitas Jr. – Consultant Engineer

3 RD INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 PAUTE MAZAR PROJECT - REPUBLIC OF ECUADOR Ø Paute Mazar Hydroelectric Project, HIDROPAUTE and CELEC S. A. Mazar Project main dam: • 166 m high CFRD and 340 m long crest , topped in elev. 2, 164 m • upstream slopes 1. 4 H : 1 V and downstream slopes 1. 25 H: 1 V • rockfill volume 5, 350, 000 m 3 • Valley shape ratio A/H 2 of 1. 7 Mazar site view Manoel S. Freitas Jr. – Consultant Engineer

3 RD INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 PAUTE MAZAR PROJECT FACE SLAB : Total 28 slabs • 10 (ten) 15 m wide slabs in left abutment. • 18 slabs 7. 5 m wide from center part area to right abutment sharp geometry at right abutment Face slab view at 2009 Mazar Dam – Cross Section zoning Manoel S. Freitas Jr. – Consultant Engineer

3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 PERIMETER JOINT At river bed and left bank areas a double cooper waterstop (bottom and top) and fly ash and mettalic protection (perforated) top cover were designed – Type 1. In addition, a very soft expanded polystyrene material (styrefoam) was placed along the perimeter joint between plinth and slab at river bed area. At right bank a corrugated GB rubber joint, designed and manufactured by China Institute of Water Resources and Hydropower Research (IWHR).

3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 Mazar up lift effect at plinth and face slab low areas In August 2008, 2 nd stage slabs were cast up to El. 2079. By August 2008 the accumulated rockfill production achieved 4, 500, 000 m 3 with an daily average pick of 22, 000 m 3. Drainage facilities at dam river bed areas were implemented by two metallic pipes (2 x Ø 6 inches ) embedded in the rockfill and connected to an outside pumping system. Drainage facilities : 2 x Ø 6” metallic pipes connected to pumping system VIEW OF DRAINAGE SYSTEM LEAKAGE WATER THROUGH PERIMETRIC JOINT DUE LACK OF A GOOD DRAINAGE SYSTEM

3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD river bed slabs view In July 2008 after intense rainy period, rockfill piezometric level raised significantly at lower areas, as recorded by foundation monitoring cells installed at Zone 2 A. In addition, Paute river W. L. ( Water Level) flood at downstream areas has contributed also in growing up the piezometric levels at upstream dam lower parts ( zone 2 A). Mazar up lift effect at plinth and face slab low areas With all these mentioned and unexpected issues the drainage facilities at plint low areas was not capable to dissipate de high up lift effect, and have caused an uplift effect and moving up displacements of slabs river bed areas, below El. 2030.

3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 In addition, slabs edges displacements have provoked high compression stresses and spalling along plinth perimeter joint (bulging effect, probably). Further site inspection shown that very soft material – expanded polystyrene, polystyrene placed along the perimeter joint has induced harmful effect ( spalling) at plinth structure. expanded polystyrene material (styrefoam)

3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 Slabs lower parts up lifting (13 A & 15 B) due drainage system shortage and concrete harmeful effect due (expanded polystyrene joint low moduli) Slab uplift movements & Spalling effect

3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 Slabs lower parts up lifting due drainage system shortage and concrete harmeful effect due (styrofoam joint low moduli) Before perimeter joint (perforated metallic protection) removing Concrete spalling along plinth at river be area After perimeter joint (perforated metallic) and copper joint removing perimeter joint (perforated metallic protection) removing and copper joint remains

3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 expanded polystyrene material after slab uplift movements and collapse Spalling Plinth concrete Mazar up lift effect at plinth and face slab low parts movements during construction have been recorded due to : q Rockfill lower parts upstream bulking during Zones 3 B and 3 C building up ; q Uplift slab movements ( downstream areas); drainage facilities shortage due river flood at

3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 PLINTH REPAIRING WORKS MAIN INSTRUCTIONS v v v Removing cover metallic bulb and fly ash containers; Take out the top copper waterstop and to remove spalling concrete; Concrete parts cutting 4 cm bellow the plinth reinforcement; Anti spalling reinforcement bars (100 x 6 mm) welding at the plinth reinforcement ; Concrete placement (25 MPa at 28 days); Concrete cutting works (circular electric diamond tool), 20 mm wide opening and 40 cm deep, along all perimeter joint; (Figure 7); v Replace an expanded polystyrene (styrefoam) by a wood joint (18 mm x 350 mm) treated with asphalt coat along the 20 mm opening; v Placement of fly ash, geotextil and cover metallic bulb containers along the perimeter joint (no top cooper waterstop);

3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 Stress x strain tests for joint material selection expanded polystyrene (styrefoam

3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 MAZAR CFRD STRESS X STRAIN TESTS FOR SEVERAL JOINTS MATERIAL Sample 1: wood material ( Madera Seiquex ) INITIAL SAMPLE THICKNESS 21. 2 mm SAMPLE THICKNESS AFTER TESTS 14. 6 mm Density = 543 Kg/m 3 At 50% deformation test= 13. 5 Mpa

3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 INITIAL SAMPLE THICKNESS : SAMPLE THICKNESS AFTER TESTS : Density = 20 Kg/m 3 At 50% of deformation test = 0, 18 Mpa 45, 6 mm 30 mm Not recommended as joint material

3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 INITIAL SAMPLE THICKNESS : SAMPLE THICKNESS AFTER TESTS : Density = 1, 372 Kg/m 3 At 50% of deformation test = 3. 75 Mpa 42, 9 mm 41, 7 mm

3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 Comparison among tests material for joints Sample 1: wood material ( Madera Seiquex ) INITIAL SAMPLE THICKNESS 21. 2 mm SAMPLE THICKNESS AFTER TESTS 14. 6 mm Density = 543 Kg/m 3 At 50% deformation test= 13. 5 Mpa Sample 2: Material expanded polystyrene (styrefoam) INITIAL SAMPLE THICKNESS : SAMPLE THICKNESS AFTER TESTS : 45, 6 mm 30 mm Quite soft material do not recommended for joints Density = 20 Kg/m 3 At 50% of deformation test = 0, 18 Mpa Sample 3: Material Neoprene INITIAL SAMPLE THICKNESS : SAMPLE THICKNESS AFTER TESTS : 42, 9 mm 41, 7 mm Density = 1, 372 Kg/m 3 At 50% of deformation test = 3. 75 Mpa

3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 Main topic remarks related Mazar CFRD Joints Ø a bottom cooper waterstop and a second top cooper waterstop (protected by a fly ash enveloped by a geotextil and protected by a perforated metallic cover) double concept (Fly ash type design used in El Cajon CFRD, Mexico) However, this double cooper joint concept did not avoid leakage throughout perimeter joint due slabs up lift displacements. Joint design used in El Cajon CFRD, Mexico

3 rd INTERNATIONAL SYMPOSIUM ON ROCKFILL DAMS KUNMING, YUNNAN PROVINCE, NOVEMBER 1 ST – 3 RD , 2013 FINAL CONSIDERATIONS Ø Drainage facilities at upstream lower areas during construction are mandatory to control and to protect against slabs uplift along perimeter jointand movements due relevant piezometric head pressures at downstream plinth areas. Ø Face slab upstream bulging displacements at lower parts during construction should be concerned by designers In Mazar dam, plinth rupture and spalling harmfull effects were induced due shortage drainage system combined with slab bulging movements. Soft expanded polystyrene material ( deforming capacity of around 50 % less (< ) 1 Mpa can not be applied. In Mazar CFRD, repairing works procedures and re build part of plinth and perimeter joint river bed areas on time, without no interference in the contractual construction schedule. Safety slab conditions at lower river bed areas have been kept and be assured by upstream fill building up to El. 2060.