Download - Under Water Retrofitting Hani
UNDERWATER INSPECTION OF BRIDGES ILLUSTRATED WITH
CASE STUDYBY
Hani Aboobacker
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 POSSIBLEMISHAP DUE TO STRUCTUREFAILURE BY TIMELY ACTION
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 /CONCRETECAVITY IN MASONRY /CONCRETE•JOINTS IN MASONRY /CONCRETEJOINTS IN MASONRY /CONCRETE
•LOOSE/ MISSING STONE/BRICKS IN MASONRYLOOSE/ MISSING STONE/BRICKS IN MASONRY•WEATHERING OF MASONRYWEATHERING OF MASONRY•EXPOSURE OF REINFORCEMENTEXPOSURE OF REINFORCEMENT
• 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
WHAT SHALL BE INSPECTED IN UW INSPECTION? (CONTD)
Anerobic Bacterial Growth
Scaling of concrete
Spalling of concrete
Disintegration of concrete
Deep Cavitation
WHO WILL DO UNDER-WATER INSPECTION?
• ONLY WELL TRAINED PERSONNELONLY 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
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
METHODS OF PERFORMING UNDER-WATER INSPECTION
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
1.WADING INSPECTION – BASIC, REGULAR METHID OF INSPECTION – PROBING/SOUNDING ROD
……. 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
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
• IS 10291-1982 LAID DOWN – QUALIFICATION OF DIVERS AND SUPERVISORS– 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.
SAFEGUARDS FOR THEIR WORKING
• 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
……. CONTD SCUBA DIVING & SAFE GUARDS FOR DIVERS)
• 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
TOOLS REQUIRED
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
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
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
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
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
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
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 SIDEPROCEDURE FOR CONCRETE PIERS
•INSPECT CONDITION OF CONCRETE. TAKE PHOTOS AS REQD•MEASURE DIMENSIONS OF SPALLS &RECORD LOCATION•INSPECT CRACKS AND MEASURE SIZE, LENGTH&LOCATION
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 RDSOACTION TO BE TAKEN ON RESULTS OF U/W INSPECTION•MINOR DEFECTS– SUCH AS CRACKSMINOR DEFECTS– SUCH AS CRACKS
-AQUA RESINS FOR GROUTING REPLACING WATER-AQUA RESINS FOR GROUTING REPLACING WATER
–CRACK >6mm sand with grouting resinsCRACK >6mm sand with grouting resins
–SPECIAL GROUTING EQUIPMENTSSPECIAL GROUTING EQUIPMENTS
• PREPARATION OF SURFACE BY WATER JET AT HIGH PRESSURE
• APPLYING THICK COAT OF EPOXY RESIN ON THE PREPARED SURFACE FOR BONDING
• EPOXY MORTAR
SPALLING OF CONCRETE
• 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 TECHNIQUESFOR CONCRETE PILES
• TREMIE CONCRETE• BOTTOM OPENING SKIP BOX• BAGGED CONCRETE• GROUT INJECTION OF PREPLACED AGGREGATE
REPAIR BY UNDERWATER CONCRETING
• 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
TREMIE CONCRETETREMIE CONCRETE
• 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
CASE STUDY OF Br. No.1201 ON SRR-MAQ SECTION ON S.Rly
BRIDGE No.1201 AT Km.837/100-500 ON DOWN LINEON RIVER PYSAVALI WITH SPAN 3 x 30.48+ 18 x 15.24
•1ST 3 SPANS ARE 100’ON RIVETTED UNDERSLUNG GIRDERS
SUPER STRUCTURE – RIVETTED STEEL PLATE 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
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
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
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
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
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 UNITMATERIALS USED FOR THE WORK
160 NO.S OF 25 KG RENDEROC UW BAGS, 20 NO.S OF PLUGIN 5 KG BAGS, 200 No.S 25 KG 6MM AGGREGATE BAGS ETC
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
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 THESEPRODUCTS.
•PERFORMANCE TILL DATE IS SATISFACTORY.
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
Thank youThank youThank you