Presentation on DIAGNOSTIC ANALYSIS OF DISTRESSED HYDRAULIC STRUCTURES: CASE STUDIES OF GUJARAT, INDIA by Er Vivek P Kapadiya, Chief Engineer & Additional Secretary, Government of Gujarat at #33NCCE #IEIGSC

1. DIAGNOSTIC ANALYSIS OF DISTRESSED HYDRAULIC
STRUCTURES: CASE STUDIES OF GUJARAT, INDIA
VIVEK P. KAPADIA
GOVERNMENT OF GUJARAT

2. 2
Backtracking from Symptoms to Causation
Forensic Analysis
Cause

3. CASE STUDY – 1 NARMADA MAIN CANAL

4. DESIGN FEATURES OF MAIN CANAL
• LARGEST IN THE WORLD HAVING CARRYING CAPACITY OF 1133 CUBIC
METER PER SECOND AT THE OFF-TAKE POINT.
• AT CH. 195 KM BANK HEIGHT ABOVE THE GROUND LEVEL IS 12.5 M
• CANAL BED IS 70 M WIDE AND THE FULL SUPPLY DEPTH (FSD) IS 7.0 M
• DESIGNED DISCHARGE IS 825 M3
/S
• CANAL SIDE SLOPES ARE 2 (H) : 1 (V)
4

5. DIAGNOSIS OF THE PROBLEM
BOILING

6. DIAGNOSIS OF THE PROBLEM
• BOILING AT SOME DISTANCE FROM THE TOE OF THE CANAL
EMBANKMENT
• SUBSURFACE FLOW DUE TO FAVORABLE HYDRAULIC GRADIENT -
COULD NOT BE ATTRIBUTED TO THE CANAL FLOW AS THE CANAL WAS
LINED AND THE BED BANKING WAS MORE THAN 3.5 METER
• SHALLOW LIVE AQUIFER - CUT DUE TO CONSTRUCTION OF THE CANAL
SIPHON IN THE DOWNSTREAM

7. DIAGNOSIS OF THE PROBLEM
BOILING
SHALLOW AQUIFER

8. DIAGNOSIS OF THE PROBLEM
• SEEPAGE ABOVE TOE - EITHER PHREATIC LINE DEVELOPED WITHIN THE
CANAL EMBANKMENT OR CAPILLARY ACTION DEVELOPED NEAR THE
TOE FROM WITHIN THE GROUND ITSELF OR BOTH TOGETHER
• LOAM TYPE OF SOIL - GENERALLY ERODIBLE AND PHREATIC LINE OR
CAPILLARY ACTION COULD BE EASILY DEVELOPED DUE TO HIGH
PERMEABILITY WHEN THE COMPACTION IS NOT SUFFICIENT
• DEEP RAIN-CUTS ON THE OUTER SIDE OF THE CANAL EMBANKMENTS
WERE ALSO OBSERVED WHICH ALSO SUGGESTED ERODIBLE SOIL

9. UNFOLDMENT OF SOLUTION OF THE PROBLEM
• EXIT TO THE SUBSURFACE FLOW BY PROVIDING A LATERAL DRAIN -
ESTABLISH A STEADY STATE OF THE SOIL BENEATH THE CANAL
EMBANKMENT SO THAT CRUMBLING OF THE FOUNDATION RESULTING IN
TO FAILURE OF THE EMBANKMENT COULD BE AVOIDED
• ALSO TO STOP THE CAPILLARY ACTION OF WATER IN TO THE CANAL
EMBANKMENT NEAR THE TOE IF ANY
• LATERAL DRAIN - A COLLECTING DRAIN WAS EXTENDED TO A FAR
SITUATED POND FOR THE DISPOSAL
• AIMED AT RELEASING THE WATER ACCUMULATED IN LARGE QUANTITY
WITHIN THE SOIL BENEATH THE CANAL EMBANKMENT

10. UNFOLDMENT OF SOLUTION OF THE PROBLEM
BOILING
SHALLOW AQUIFER

11. UNFOLDMENT OF SOLUTION OF THE PROBLEM
• OBSERVATION FOR SOME DAYS - BOILING PHENOMENON ALMOST DISAPPEARED -
SEEPAGE REDUCED BUT NOT COMPLETELY STOPPED WHICH SUGGESTED THAT THE
PHREATIC LINE HAD ESTABLISHED WITHIN THE EMBANKMENT
• ADDITIONAL BERM OF 5 METER WIDTH AND 5 METER HEIGHT
• JUTE TEXTILE BAGS WERE SPECIALLY DESIGNED IN THE FORM OF LONG ROLLS -
FILLED UP WITH CEMENT SOIL IN 1:9 RATIO AND NAILED ON THE OUTER SLOPE OF
THE CANAL EMBANKMENT
• AVOIDING ROLLING DOWN OF THE JUTE ROLLS, AN ANTI-EROSION SURFACE ON
THE OUTER SLOPE OF THE EMBANKMENT AND TO ADD EXTRA BURDEN TO PROVIDE
MORE STABILITY

12. UNFOLDMENT OF SOLUTION OF THE PROBLEM

13. CASE STUDY – 2 GORATHIYA DAM

14. INTRODUCTION
• SABARKANTHA DISTRICT I.E. IN NORTH GUJARAT IN INDIA - COMPLETED BEFORE 10
YEARS - RIVER MESHWO
• GROSS STORAGE CAPACITY - 146 MILLION CUBIC FEET
• CATCHMENT AREA IS 371 SQUARE KILOMETERS - DESIGNED FLOOD WITH 1 IN 50 YEAR
FREQUENCY IS 3774 CUBIC METER PER SECOND
• LENGTH OF THE SPILLWAY SECTION IS 101.80 METER - CONCRETE GRAVITY DAM WITH
PROVIDED 9 VERTICAL GATES - HYDRAULIC JUMP TYPE STILLING BASIN - UPSTREAM
AND DOWNSTREAM KEYS WERE 3.5 METER DEEP

15. INTRODUCTION
• SIGNS OF DISTRESS IN ONLY 2 YEARS
• DOWNSTREAM GLACIS SLOPE 1:3 - TOE GOT DISINTEGRATED AND THE
REINFORCEMENTS WERE PULLED OUT
• DOWNSTREAM APRON GOT DAMAGED BUT NOT IN THE ENTIRE LENGTH OF THE DAM,
ONLY IN THE RIGHT HALF OF THE LENGTH I.E. RIVER’S HALF WIDTH

16. INTRODUCTION
PULLED OUT REINFORCEMENT

17. INTRODUCTION
PULLED OUT REINFORCEMENT AT TOE AND DAMAGED APRON

18. DIAGNOSTIC ANALYSIS
• GLACIS WITH 1:3 SLOPE WAS INSUFFICIENT TO AVOID CAVITY FORMATION - THERE
SHOULD HAVE BEEN A MUCH FLATTER SLOPE OR AN OGEE
• SOME RECORD - ORIGINALLY A BASALT MINE AS THE RIVER WAS HAVING GOOD
QUALITY BASALT IN ITS BED - FOR PREPARATION OF THE SITE, THE DESIGN
INCLUDED LEAN CONCRETE FILLING WITH LARGE COARSE AGGREGATE I.E. PLUM
CONCRETE IN THE PIT
• SOME OTHER RECORDS WITH GEOLOGICAL MAPPING SUGGESTED THAT THE MINE
WAS ONLY IN THE RIGHT HALF WIDTH OF THE RIVER AND THE DEPTH WAS ABOUT 9
METER

19. DIAGNOSTIC ANALYSIS
• LARGE COARSE AGGREGATES WERE IN PLACE - CEMENT AND SAND WERE IN LOOSE
FORM - WATER BENEATH THE APRON IN THE VOIDS - DAM WAS FULL UP TO CREST
LEVEL - IT WAS THE WATER FROM THE RESERVOIR
• CONDITION WAS EXTREMELY DANGEROUS - SUBSURFACE FLOW COULD RESULT IN
TO UNDERMINING THE FOUNDATION AND COLLAPSE OF THE CONCRETE DAM
ITSELF.
• WHEN WATER WAS RELEASED, IMPACT OF THE WATER FALL WAS TAKEN UP BY THE
APRON WHICH REQUIRED A SOLID FOUNDATION WHICH ACTUALLY WAS NOT
THERE - CONCRETE APRON USED TO SETTLE - SAGGING RESULTING IN TO DAMAGE
AT THE BOTTOM AND TOP – BOTTOM DAMAGE WAS NOT VISIBLE BUT THE TOP WAS

20. RESTORATION
• PLUM CONCRETE REMOVED UP TO 1.5 METER DEPTH – RICH CEMENT SAND MIX 1:4
WITH POLYMER POURED TO PLUG VOIDS IN PLUM CONCRETE
• LAYER OF 1.5 METETR THICKNESS OF RICH CONCRETE
• ADDITIONAL PERIPHERAL KEY OF 5 METER – FOUNDATION OF ABUTMENT
STRENGTHENED
• CASTING OF APRON – REINFORCEMENT MESH AT TOP WELDED WITH TOE
REINFORCEMENT – SURFACE HARDENER TO PROVIDE IMPACT RESISTANT SURFACE –
FILLET AT TOE
• DOWNSTREAM RIVER CHANNEL REGRADED

21. RESTORATION

22. RESTORATION

23. CONCLUSION
• PROBLEMS IN CIVIL ENGINEERING ARE VERY COMPLEX AND UNDERSTANDING THE
REAL CAUSE OF THE PROBLEM IS THE MOST IMPORTANT ASPECT
• A SMALL ASPECT IGNORED AT THE CONSTRUCTION STAGE MAY LEAD TO DIFFICULT
PROBLEMS
• EXPERIENCE AND INSIGHT NEEDED AS MOSTLY THE FINDINGS CAN BE REACHED BY
WAY OF USING JUDGMENTAL AND INTUITIVE DECISIONS

24. CONCLUSION
• SOMETIME THE DIAGNOSIS IS REQUIRED TO BE DONE STAGE-WISE ALONG WITH STEP
BY STEP IMPLEMENTATION OF SOLUTION
• SEVERAL ACTIVITIES TO BE EXECUTED WITH PROPER SEQUENCE AND PROPER
MATERIALS

25. THANKS