UNDERWATER INSPECTION OF BRIDGES ILLUSTRATED WITH CASE STUDY BY Shri. K.Simon , Dy.CE/C/SCR Shri Mohd. Bakhs

1. UNDERWATER INSPECTION OF BRIDGES ILLUSTRATED WITH CASE STUDY BY Shri.K.Simon, Dy.CE/C/SCR Shri Mohd. Bakhsh, Dy.CE/W/WR Shri .A.Raj Kumar, DEN/SR

2. WHY UNDER-WATER INSPECTION? • TO ENSURE SAFE CONDITION • OF SUB-STRUCTURE DURING • THE COURSE OF ITS LIFE. • TO DETECT ANY DISTRESSED • CONDITION OF SUB-STRUCTURE • OUT LIVED OR PRE-MATURE • TO PREVENT ANY POSSIBLE • MISHAP DUE TO STRUCTURE • FAILURE BY TIMELY ACTION

3. WHERE UNDER-WATER INSPECTION IS ESSENTIAL? • IT IS REQUIRED TO CHECK THE SUBSTRUCTURE OF ALL • BRIDGES OVER PERENNIAL RIVERS &BACKWATERS. • ON BRIDGES WHERE SUBSTRUCTURE CANNOT BE • INSPECTED DUE TO SUBMERGING UNDER WATER WHAT SHALL BE INSPECTED IN UW INSPECTION? • CAVITY IN MASONRY /CONCRETE • JOINTS IN MASONRY /CONCRETE • LOOSE/ MISSING STONE/BRICKS IN MASONRY • WEATHERING OF MASONRY • EXPOSURE OF REINFORCEMENT

4. WHAT SHALL BE INSPECTED IN UW INSPECTION?(CONTD) • RUST STAINING, CRACKING, SPALLING, ABRASION, DISINTEGRATION IN CONCRETE STRUCTURES • BULGING IN SUB STRUCTURE • STEEL WORKS --CI PIPES -- STEEL CAISSONS -- SCREW PILES • CORRECT LOCATION AND IDENTIFICATION OF DEFECTS IS IMPORTANT

5. Anerobic Bacterial Growth

6. Scaling of concrete

7. Spalling of concrete

8. Disintegration of concrete

9. Deep Cavitation

10. WHO WILL DO UNDER-WATER INSPECTION? • ONLY WELL TRAINED PERSONNEL • PRACTICAL PROBLEM IS THAT IN MAJORITY OF THE • CASES ONLY EXPERT DIVERS ARE USED BUT THEY • WILL NOT HAVE ANY EXPERTISE IN CIVIL/ BRIDGE ENGG. WHAT IS LAID DOWN IN OUR CODES ON THIS TOPIC? • CODES INCLUDING IRBM’98 IS SILENT ABOUT THIS ASPECT • AFTER TRAGIC KADALUNDI ACCIDENT, BASED ON CCRS • RECOMMENDATIONS, RDSO HAS BROUGHT OUT BS-40 • GUIDE LINES FOR UNDERWATER INSPECTION OF BRIDGES • DURING THE YEAR 2001. CE’S CIRCULAR No.3/2002 OF Srly PRESCRIBED 2 YEARS FERQUENCY

11. WHEN TO CONDUCT UNDERWATER INSPECTION? • BS-40 SUGGESTS DURING THE PERIOD OF LOW WATER • OR LOW POLLUTION LEVELS OR GOOD VISIBILITY (UNDER) • 20% OF UNDERWATER UNITS FOR EACH BRIDGE SELECTED RANDOMLY SHOULD BE INSPECTED. THE RANDOM INSPECTION SHOULD BE MADE IN SUCH A WAY THAT ENTIRE STRUCTURE IS COVERED IN 5 YEARS

12. METHODS OF PERFORMING UNDER-WATER INSPECTION 1.WADING INSPECTION – BASIC, REGULAR METHID OF INSPECTION – PROBING/SOUNDING ROD 2.SCUBA -SELF CONTAINED UNDERWATER BREATHING APPRATUS 3. SURFACE SUPPLIED AIR DIVING OR MIXED GAS DIVING 4.DEEP SEA DIVING – NOT USED FOR BRIDGE INSPECTION SCUBA DIVING • SCUBA DIVER IS PROVIDED WITH PORTABLE AIR SUPPLY • & IS CONNECTED TO SURFACE THROUGH AN UMBILICAL • CABLE • MIN.EQUIPMENT ARE SCUBA, LIFE PRESERVER,WEIGHT • BELT, KNIFE,FACE MASK AND SWIM FINS

13. ……. CONTD SCUBA DIVING) • IS SUITED WHEN MANY DIVES OF SHORT DURATION • ARE NEEDED & MOBILITY IS THE PRIME CONSIDERATION • MERITS ARE RAPID DEPLOYMENT, PORTABILITY, MIN. • SUPPORT AND EXCELLENT MOBILITY • DEMERITS ARE DEPTH LIMITATION, MIN.AIR SUPPLY • LACK OF VOICE COMMUNICATION FROM SURFACE • MAX. SUSTAINED TIME AND DEPTH IS ONE HOUR @18 M • DIVING TEAM SHOULD HAVE 3 MEN & BOAT IS REQUIRED

14. SURFACE SUPPLIED AIR DIVING • AIR IS SUPPLIED TO THE DIVER THROUGH UMBILICIL HOSES, CONNECTED TO THE SURFACE AIR COMPRESSOR TANK • COMMUNICATION CABLE, LIFE LINE, PNEUMATIC FATHOMETER ARE ATTACHED TO THE DIVER • SUITED FOR IN ADVERSE CONDITION – HIGH STREAM VELOCITY, POLLUTED/TURBID WATER AND LONG DURATION/DETAILED INSPECTION • UNLIMITED AIR SUPPLY • SUSTAINED TIME – 60 MINUTES AT 18m DEPTH

15. IS 10291-1982 LAID DOWN • QUALIFICATION OF DIVERS AND SUPERVISORS • SAFEGUARDS FOR THEIR WORKING SAFEGUARDS FOR THEIR WORKING • MINIMUM AGE 18 YEARS • FITNESS BY DOCTOR IN LAST SIX MONTHS • FITNESS TESTED FOR WORK AT REQUIRED DEPTH OR EQUIVALENT PRESSURE IN COMPRESSION CHAMBER • KNOWLEDGE OF DIVING SIGNALS • TRAINED FOR WORK IN NO VISIBILITY CONDITIONS AND 0.6M DEPTH OF MUD AND CONDUCT SEARCH ETC.

16. ……. CONTD SCUBA DIVING & SAFE GUARDS FOR DIVERS) • GOOD PHISIQUE,CAPABLE OF SUSTAINING STRAIN • FREE FROM CARDIAC PROBLEM • FREE FROM MID EAR PROBLEM ETC • NOT ADDICTED TO ALCOHOL AND EXCESS SMOKING • MORE THAN 45 YEARS NOT BE EMPLOYED FOR DEEP DIVING • SELECT AGE >30YEARS FOR TRAINING • DIVERS DRESS,HELMET,COMPRESSED AIR AND ACCESSORIES • STANDARD EQUIPMENTS TOOLS REQUIRED • VIDEO CAMERAS /CLOSE CIRCUIT TV CAMERAS AND TV MONITOR • TELEMETRY LINK TO OPERATE CAMERA • COMMUNICATION SYSTEM WITH AMPLIFIER AND LOUD SPEAKERS ETC • UNDERWATER LAMP/HEAD LAMP

17. TYPES OF INSPECTION AND INTENSITY LEVELS • LEVEL I-VISUAL,TACTILE INSPECTION(ROUTINE INSPECTION) • LEVEL II-DETAILED INSPECTION WITH PARTIAL CLEANING • LEVEL III-HIGHLY DETAILED INSPECTION WITH NDT LEVEL I-INSPECTION • GENERAL VISUAL ROUTINE INSPECTION • COVERED OVER EXTERIOR SURFACE • PROBING OVER SUBSTRUCTURE AND STREAMBED • TO DETERMINE THE NEED FOR LEVEL II/III INSPECTION

18. TYPES OF INSPECTION (Contd..) LEVEL II INSPECTION • TO BE CONDUCTED BASED ON REPORT OF LEVEL I INSPECTION • NEEDS CLEANING OF STRUCTURAL ELEMENT • DETAILED INVESTIGATION OF SELECTED COMPONENTS • ATLEAST 20% OF ALL UNDERWATER ELEMENTS TO BE COVERED • SIMPLE INSTRUMENTS –CALIPPERSE AND SCALE TO IDENTIFY EXTENT AND SEVERITY OF DAMAGE

19. TYPES OF INSPECTION (Contd..) LEVEL III INSPECTION • HIGHLY DETAILED INSPECTION OF A CRITICAL STRUCTURE OF STRUCTURAL ELEMENT • INCLUDES EXTENSIVE CLEANING, DETAILED MEASUREMENTS • SELECTED NDT/PARTIALLY DISTRUCTIVE TESTING SUCH AS ULTRASONIC, SAMPLE CORING, IN-SITU HARDNESS TESTING Etc.. • REQUIRES MORE EXPERINCE AND TRAINING

20. UNDERWATER INSPECTION PROCEDURE • INTIAL INSPECTION REQUIRES CAREFUL PLANNING • PRIOR SITE SURVEY FOR SELECTION OF INSPECTION METHODS, TYPE AND INTENSITY LEVEL, EQUIPEMENT REQUIRED • REVIEW OF AVAILABLE RECORDS AND PAST HISTORY • AVAILABILITY OF TOOLS AND PLANTS • ABILITY/QUALIFICATION OF DIVING TEAM • SCOUR INVESTIGATION • INSPECTION OF SUB STRUCTURE

21. UNDERWATER INSPECTION PROCEDURE (Contd..) UNDERWATER NDT INSPECTION • SOUNDING/SENSING DEVICE- FOR CHECKING SCOUR IN THE STREAM BED • REBOUND HAMMER- SURFACE HARDNESS TESTER – TO OBTAIN GENERAL CONDITION OF CONCRETE • MAGNETIC REBAR LOCATION- TO DETERMINE THE LOCATION AND ORIENTATION OFREBAR • ULTRASONIC SYSTEM FOR CONCRETE- TO CHECK UNIFORMITY OF CONCRETE FROM ONE LOCATION TO THE OTHER

22. UNDERWATER NDT INSPECTION (Contd..) • ULTRASONIC THICKNESS METRES – TO MEASURE THE THICKNESS OF THE STEEL • UW MAGNETIC PARTICLE TESTING – TO DETECT SURFACE CRACKS • RADIOGRAPHY– TO DETECT INTERNAL DEFECTS/FLAWS

23. PROCEDURE OF UNDER-WATER INSPECTION BY DIVERS • LIST &CHECK THE WORKING OF ALL TOOLS &EQUIPMENT • BOATS & LIFE PRESERVERS AS REQUIRED • CAMERAS • INSPECTION DOCUMENTS, PAPER,CLIP BOARD &PENCILS • CONCRETE OR STEEL TOOL KIT AS APPLICABLE • SOUNDING EQUIPMENT &MARKING PENCILS(FOR SCOUR) • SAFETY EQUIPMENT(ROPES, BUOYS&MANNED SAFETY BOAT) PROCEDURE FOR CHECKING PIERS FORMED OF PILES • TWO DIVERS TO INSPECT SAME PILE. • IF VISIBILITY IS POOR, PUT LIGHT CLOSE AND INSPECT • DIFFERENT FACES AND TURN LATER TO UNINSPECTED SIDE PROCEDURE FOR CONCRETE PIERS • INSPECT CONDITION OF CONCRETE. TAKE PHOTOS AS REQD • MEASURE DIMENSIONS OF SPALLS &RECORD LOCATION • INSPECT CRACKS AND MEASURE SIZE, LENGTH&LOCATION

24. DOCUMENTAION OF THE RESULTS OF U/W INSPECTION • RECORD THE RESULTS OF UNDER-WATER INSPECTION • IN THE PROFORMA PRESCIBED IN ANNEXURE-II,III&IV OF • BS-40 “GUIDE LINES FOR U/W INSPECTION ISSUED BY RDSO ACTION TO BE TAKEN ON RESULTS OF U/W INSPECTION • MINOR DEFECTS– SUCH AS CRACKS • -AQUA RESINS FOR GROUTING REPLACING WATER • CRACK >6mm sand with grouting resins • SPECIAL GROUTING EQUIPMENTS SPALLING OF CONCRETE • PREPARATION OF SURFACE BY WATER JET AT HIGH PRESSURE • APPLYING THICK COAT OF EPOXY RESIN ON THE PREPARED SURFACE FOR BONDING • EPOXY MORTAR

25. REPAIR TECHNIQUES FOR CONCRETE PILES • JACKETING BY SHOTCRETE/GUNITE LAYER OF 75MM THICKNESS OR SO • SHOTCRETE RING IS PREPARED ABOVE LOW WATER LEVEL AND LOWERED UPTO BOTTOM • ANNULAR SPACE IS SUBSEQUENTLY GROUTED WITH MORTAR DISPLACING WATER REPAIR BY UNDERWATER CONCRETING • TREMIE CONCRETE • BOTTOM OPENING SKIP BOX • BAGGED CONCRETE • GROUT INJECTION OF PREPLACED AGGREGATE

26. TREMIE CONCRETE • DESIGNED FOR LOW STREGTH UPTO M20 • SLUMP 150-200mm • COHESIVE AND SHOULD NOT SEGREGATE DURING TRANSPORT OR PLACEMENT • W/C RATIO =<0.5 • CEMENT CONTENT HIGH 400 KG/CUM • PLASTICISERS FOR WORKABILITY • TREMIE PIPE DIA 20MM AGRT-150MM • 40MM 200MM • BOTTOM OF PIPE 300-400 MM IMMERSED IN CONCRETE • MORE THAN 30 SQM AREA MORE THAN ONE PIPE • IF MORE THAN ONE LIFT DIVERS TO PREPARE SURFACE BY REMOVING LAITANCE

27. CASE STUDY OF Br. No.1201 ON SRR-MAQ SECTION ON S.Rly BRIDGE No.1201 AT Km.837/100-500 ON DOWN LINE ON RIVER PYSAVALI WITH SPAN 3 x 30.48+ 18 x 15.24 SUPER STRUCTURE – RIVETTED STEEL PLATE GIRDERS • 1ST 3 SPANS ARE 100’ON RIVETTED UNDERSLUNG GIRDERS • NEXT 18 SPANS ARE 40’ RIVETTTED PLATE GIRDERS BEARINGS- 1ST 3 SPANS – ROCKER & ROLLER TYPE REST ALL – CENTRALLY ARTICULATED SUB-STRUCTURE PIERS 1,2,3, 5,7,9,11,13,15,17,19 & A1 AND A2 ON CR MASONRY PIERS REST 4,6,8,10,12,14,16,18 AND 20 ARE MASS CONCRETE

28. FOUNDATION WELL FOUNDATION WITH TWIN CIRCULAR MASONRY WELL HISTORY OF THE BRIDGE 1.BRIDGE WAS BUILT IN 1906 AS 12 X 30.48 M UNDER SLUNG RIVETTED PLATE STEEL GIRDER BRIDGE ON ROCKER AND ROLLER BEARINGS, ON CRS MASONRY PIERS WITH STONE MASONRY TWIN CIRCULAR WELLS 2. DURING 1960-1970, THOUGH CLEAR RECORDS ARE NOT AVAILABLE, 9 SPANS FROM 4TH TO 12TH ARE DIVIDED AS 2 EACH MAKING BRIDGE AS 3x 30.48+18x 15.24 WITH 18 SPANS WITH RIVETTED PLATE GIRDERS BY PROVIDING 9 ADDITIONAL MASS CONCRETE PIERS ON CR MASONRY TWIN CIRCULAR WELL FOUNDATION REASONS FOR SUCH CHANGE IS NOT DOCUMENTED

29. OBSERVATIONS PRIOR TO IDENTIFICATION OF PROBLEM ON Br1201 • FREQUENT ATTENTION TO CROSS-LEVEL NEAR P4 • (Right Rail low) • FREQUENT MIS-ALIGNMENT ON-TO ONE SIDE • NON-RETENTION OF RECTIFIED CROSS-LEVEL & ALIGNMENT ACTION TAKEN ON THE OBSERVATIONS • INITIALLY FORTNIGHTLY THEN WEEKLY RECORDING OF • PARAMETERS DONE. ON GETTING PROGRESSIVE CHANGE • UNDER- WATER INSPECTION WAS ORDERED • ON 20.02.2002 DIVERS INSPECTED THE SUB-STRUCTURE • & REPORTED THAT RH WELL STEINING OF P4 HAS A CAVITY • 1.25 x 0.75 x 0.50 SIZE ON EAST SIDE JUST BELOW WELL CAP

30. CONFIRMATION OF PROBLEM (IN MARCH-APRIL2002) • SUBSEQUENT TO THE REPORT BY DEPARTMENTAL DIVERS • EXPERT FROM CBE/O/MAS, SSE/BR &DIVER WAS CALLED • AND CAVITY AND ITS SIZE WAS GOT CONFIRMED. PROGRAM FOR RECTIFICATION OF THE CAVITY • BASED ON INSTRUCTIONS FROM CBE (HQ), DIVISION HAS • CALLED TENDER FOR MICRO CONCRETING WORK UNDER • WATER AND FIXED UP AN AGENCY BY 12.03.2003 • M/S DYANSOURE TREATMENT, MUMBAI IS THE AGENCY • MICRO CONCERETING WITH ANTI-WAHSABLE, ANTI-SHRINKABLE PROPERTY USING RENDEROC UW OF FOSROC MAKE WAS ORDERED IN THE AGREEMENT ALONG WITH VIDEOGRAPHY OF UNDER WATER WORK

31. TECHNICAL DETAILS OF MICRO-CONCRETING • RENDEROC UW(UW STANDS FOR UNDER WATER) OF FOSROC MAKE IS A READY TO USE DRY POWDER, A MIXTURE OF PROCESSED CEMENT WITH ADDITIVES AND FINE AGGREGATES, WHICH IMPART IT CONTOLLED EXPANSION,WATER REDUCTION AND NON-WASHABLE PROPERTIES. THIS IS PACKED IN25 kg BAGS AND DOSAGE PER YIELD IS 14.5 LITRES PER 25 KG AT W/P 0.22 • MICRO CONCRETE IS EXPECTED TO GIVE A CRUSHING • STRENGTH OF 30 N/MM2 AFTER 7 DAYS RENDEROC UW CAN BE USED IN ONE POUR FOR THICKNESS UPTO 150 MM. FOR MORE, STONE AGGREGATE OF 2 TO 10 MM GRADED SHALL BE USED AT 1:1 RATIO • 5.5 LITRES OF WATER IS TO BE ADDED FOR 25 KG BAG OF • RENDEROC UW.& CONCRETE MIXER TO BE USED FOR MIX • RENDEROC PLUG IS THE PRODUCT USED TO SEAL JOINTS

32. AGENCY’S INPUTS FOR MICRO CONCRETING MANPOWER FROM CONTRACTOR’S SIDE • ONE CIVIL ENGINERING GRADUATE AS SITE ENGINEER • ONE DIVER MATE (EX-NAVY) FOR MONITORING DIVING • ONE EXPERT DIVER, 2 DIVERS & 1 ASST. DIVER • APART FROM ABOVE, 1 BOAT AND 12 MEN ENGAGED AS • AND WHEN NEEDED FOR CONCRETING LOCALLY TOOLS & EQUIPMENT USED BY CONTRACTOR • AIR COMPRESSOR & DIESEL GENERATOR ALOGN WITH • 3 DIVING EQUIPMENT • VIDEO CAMERA FOR USING UNDER WATER, RECORDER • WITH DISPLAY UNIT MATERIALS USED FOR THE WORK 160 NO.S OF 25 KG RENDEROC UW BAGS, 20 NO.S OF PLUG IN 5 KG BAGS, 200 No.S 25 KG 6MM AGGREGATE BAGS ETC

33. MODUS OPERANDI OF MICRO CONCRETING • PHASE-1-INITIAL INSPECTION AND VIDEO RECORDING • PHASE-2-CLEANING AND PREPARATION OF SURFACE • PHASE-3 – ASSESSMENT OF QUANTITY • PHASE-4 – SHUTTERING / FIXATION OF FORM WORK • PHASE – 5 – MICRO CONCRETING • SAND BAGS WERE USED TO SUPPORT SHUTTERING • MS ANGLES AND TIES WERE USED TO SUPPORT GI SHUTTER • JOINT BETWEEN SHUTTER SHEET AND STRUCTURE WAS • SEALED WITH RENDEROC PLUG • TREMIE WAS MANUFACTURED WITH PLASTIC HOSE PIPE • FOR POURING CONCRETE INTO CAVITY. COMPACTION WAS • DONE USING RODS. DIVERS ENSURED PROPER PLACEMENT • CONCRETING COMPLETED IN 3 DAYS

34. EXPERIENCES AND SUGGESTIONS • RENDEROC UW IS GOOD FOR UNDERWATER CONCRETING • DIVERS WERE GOOD IN DIVING JOB BUT THEY HAVE VERY • LITTLE KNOWLEDGE OF CIVIL/BRIDGE ENGINEERING • SHUTTERING /POURING TECHNIQUES USED BY THE FIRM • ARE NOT VERY SATISFACTORY & TO BE UPGRADED • VIDEO RECORDING IS NOT ABLE TO THROW LIGHT FOR • THE PURPOE, IT IS INTENDED. LOCATIONS SHALL BE • GIVEN WITH METAL STRIP LIKE IDENTIFICATION MARKS • AN ACTUAL 7 DAY CRUSHING STRENGTH OF 44 M/MM2 • WAS ACTUALLY ACHIEVED AGAINST ANTICIPATED 30 N • COST CAN BE BROUGHT DOWN WITH WIDE USE OF THESE • PRODUCTS. • PERFORMANCE TILL DATE IS SATISFACTORY.

35. CONCLUSIONS • SYSTEMATIC AND SCIENTIFIC UNDERWARTER BRIDGE INSPECTION ARE VERY IMPORTANT IN BRIDGE MAINTENANCE AND MANAGEMENT • THE SIGNIFICINT DAMAGE ENCOUNTER TO THE BRIDGE CAN BE AVOIDED BY CARRYING OUT UNDERWATER INSPECTION IN TIME