GEOMEMBRANES FOR SEEPAGE CONTROL IN DAMS: NEW TECHNOLOGIES IN REHABILITATION AND NEW CONSTRUCTION

Transcription

1 Slide 1 GEOMEMBRANES FOR SEEPAGE CONTROL IN DAMS: NEW TECHNOLOGIES IN REHABILITATION AND NEW CONSTRUCTION A. Scuero, G. Vaschetti, CARPI TECH V. Subramanian, CARPI INDIA Waterproofing Specialists Third National Dam Safety Conference Roorkee, February 2017

2 Slide 2 GEOMEMBRANES ARE VERY FLEXIBLE MATERIALS WITH EXTREMELY LOW PERMEABILITY 2

3 Slide 3 CARPI GEOMEMBRANE SYSTEMS The material Composite geomembrane SIBELON CNT= SIBELON PVC geomembrane heat-bonded to a geotextile Geomembrane Imperviousness (k=6 x cm/s) Geotextile >> Tensile strength >> Puncture resistance >> Thermal dimensional stability Some transmissivity 3

4 Slide 4 This presentation focuses on rehabilitation SIBELON geocomposites have been used in rehabilitation of ALL types of dams Dam type Rehabilitation Concrete gravity 30 Buttress 5 Multiple arch 13 Arch 3 Masonry 15 Rockfill 22 Earthfill 3 RCC 8 4

5 Slide 5 CARPI GEOMEMBRANE SYSTEMS The objectives: stop leakage, dehydrate, monitor 5

6 Slide 6 PVC geocomposite has a face anchorage and a peripheral anchorage 6

7 Slide 7 COMPONENTS A drainage layer: the gap allowed between the concrete face and the geocomposite, and in many cases an additional high-transmissivity geonet A drainage collection and discharge system The waterproofing layer, a SIBELON geocomposite The face anchorage: vertical tensioning profiles The watertight perimeter seals at submersible peripheries The upper seal All metal components are stainless steel. The fastening of tensioning profiles and watertight perimeter seals is made by chemical phials 7

8 Slide 8 Installation of the drainage layer and of the face anchorage profiles (Carpi patent) 8

9 Slide 9 Installation of the waterproofing geocomposite 9

10 Slide 10 Heat-seaming of geocomposite sheets 10

11 Slide 11 Installation of the face anchorage profiles (Carpi patent) over the geocomposite 11

12 Slide 12 Waterproofing of the face anchorage profiles with PVC cover strips 12

13 Slide 13 Watertight seal Chemical anchor Epoxy resin Rubber gasket Stainless steel batten strip 13

14 Slide 14 Top seal 14

15 Slide 15 Case history in India: Kadamparai masonry dam 15

16 Slide 16 Kadamparai, India MW PUMPED STORAGE SCHEME Exposed SIBELON geocomposite Before repair After repair 38,000 lpm 100 lpm 16

17 Slide 17 Project data Masonry dam, 67 m high, owned by Tamil Nadu Electricity Board. It forms the upper reservoir of a pumped storage scheme Impounded in After ten years, leakage started through deteriorated masonry joints, cavities in the masonry, joints between monoliths, and through the foundation rock Repeated repairs by Packing and pointing the joints of the masonry Vertical drilling from the crest Grouting at close intervals Underwater treatment by chemicals and cement grouting were unsuccessful and seepage increased to unacceptable extent In 2003, after a thorough study with the involved parties, a tender was floated for an exposed geomembrane system 17

18 Slide 18 Leakage in the drainage gallery, left abutment 18

19 Slide 19 Leakage in the drainage gallery, right abutment 19

20 Slide 20 During 1999 racking and packing at selected locations was carried out on the upstream face of the dam, including chemical treatment in underwater conditions 20

21 Slide 21 In fact the chemical treatment proved to be totally unsuccessful because it got detached from the masonry and peeled off Chemical grout came out through the drainage gallery, leaving more cavities inside the masonry body of the dam Cementitious materials and fines were eroded and collected in the drainage gallery 21

22 Slide 22 CARPI hired Indian sub-contractors to execute the preliminary works which were completed by end of December

23 Slide 23 Installation of internal tensioning profiles started in mid-january

24 Slide 24 A geotextile was installed on the upstream face, to protect the geomembrane against puncturing Geotextile, 2000 g/m 2 24

25 Slide 25 The PVC geocomposite was laid over the antipuncturing geotextile SIBELON Geocomposite 2.5 mm PVC g/m 2 geotextile 25

26 Slide 26 Double bottom perimeter seal to reduce head on primary seal and to separate water drained from the upstream face from water drained from foundation : DRIP visit 26

27 Slide 27 Monitoring of the geomembrane system is made by measuring drained water, by readings at piezometers, and by the optical fibre cable system that will allow locating the area of any unattended water from a possible leak Piezometer and data logging box installed in the gallery Optical fibre cable and data logging box installed at the crest 27

28 Slide 28 Before repair 38,000 lpm After repair, at FSL (Full Supply Level) 100 lpm 28

29 Slide 29 INDIA POWER AWARDS 2008 Issued by the Council of Power Utilities of India to recognize achievements and contributions by organizations and individuals for Power sector. Awarded on November 3, 2008 with the following motivation: CARPI India Waterproofing Specialist Pvt. Ltd. was adjudged the winner in recognition of Excellence in Water and Energy Management for designing and installing first PVC geomembrane waterproofing system in Kadamparai dam IDENTICAL SZSTEM IS BEING INSTALLED IN 2017 AT SERVALAR DAM, UNDER THE DRIP, Dam Rehabilitation and Improvement Project 29

30 Slide 30 Repair of concrete gravity dams Exposed SIBELON geocomposite Lago Nero, Italy

31 Slide 31 Reair of buttress dams Pracana buttress dam, Portugal 1992, affected by AAR Owner stated that exposed SIBELON geocomposite contributed to slow AAR reaction 31

32 Slide 32 Repair of multiple arch dams Exposed SIBELON geocomposite Florence, USA, ongoing 32

33 Slide 33 Repair of arch dams Exposed SIBELON geocomposite Publino, Italy

34 Slide 34 Repair of CFRDs Exposed SIBELON geocomposite Pecineagu, Romania

35 Slide 35 Underwater repair Lost Creek arch dam, USA Example of full face repair Total leakage is drops 35

36 Slide 36 Underwater repair Platanovryssi, Greece 2002 Example of underwater repair of cracks 36

37 Slide 37 Underwater repair Olai, Italy 2013 Example of underwater repair of failing joints 37

38 Slide 38 NEW TECHNOLOGY FOR UNDERWATER REHABILITATION THE SIBELONMAT 38

39 Slide 39 Geomembrane mattresses SIBELONMAT installed in canals without dewatering nor stopping the water flow 39

40 Slide 40 Connection of SIBELONMAT mattresses with heavy duty watertight zip Ismailia, Egypt,

41 Slide 41 Detail of the SIBELONMAT mattresses after grouting Ismailia, Egypt,

42 Slide 42 Range of applications for the SIBELONMAT mattress Underwater repair of fill dams, full face or critical areas Upstream blanket, placed underwater, as waterproofing layer to improve watertightness at foundation Underwater repair of canals without stopping or reducing water speed The same system can be used to provide watertightness at construction, in fill dams, canals and reservoirs 42

43 Slide 43 KADAMPARAI, India 2005 THANK YOU FOR YOUR ATTENTION 43