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Diaphragm wall construction
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- 2. DIAPHRAGM WALL:- • DIAPHRAGMWALL IS A CONTINEOUS WALL CONSTRUCTED IN GROUND IN TO FACILIATE CERTAIN COSTRUCTION ACTIVITES,SUCH AS: A) AS A RETAINING WALL B) AS A CUT-OFF PROVISION TO SUPPORT DEEP EXCAVATION C) AS A SEPARATING STRUCTURE BETWEEN MAJOR UNDERGROUND FACILITIES D) AS A FORM OF FOUNDATION (BARRETTE PILE – RECTANGULAR PILE)
- 3. DIAPHRAGM WALL:- • DIAPHRAGMWALL IS A REINFORCED CONCRETE STRUCTURE CONSTRUCTED IN-SITU PANEL BY PANEL. THE WALL IS USUALLY DESIGNED TO REACH VERY GREAT DEPTH, SOMETIMES UP TO 50M, MECHANICAL EXCAVATING METHOD IS THUS EMPLOYED. TYPICAL SEQUENCE OF WORK INCLUDES: A) CONSTRUCT THE GUIDE WALL B) EXCAVATION TO FORM THE DIAPHRAGM WALL TRENCH C) SUPPORT THE TRENCH CUTTING USING BENTONITE SLURRY D) INERT REINFORCEMENT AND PLACING OF CONCRETE TO FORM THE WALL PANEL
- 4. FURTHER EXPLANATION ON THEWORK SEQUENCES:- • FIRST WE HAVE TO BUILD THE GUIDE WALL FOR THE DIAPHRAGM WALL • GUIDE WALL IS A PARALLEL BEAMCONSTRUCT ALONG THE SIDE OF THE WALL • WHICH IS USED FOR THEEXCAVATION FOR THE DIAPHRAGM WALL TRENCHES
- 5. GUIDE WALL:- • GUIDEWALLS ARE CONSTRUCTED IN-SITU TYPICALLY AS LIGHLY REINFORCED CONCRET E ELEMENTS. GUIDE WALLS MAINTAIN THE HORIZONTAL ALLIGNMENT AND WALL CONTINUITY OF A DIAPHRAGM WALL WHILE THE PROVIDE SUPPORT FOR THE UPPER SOILS DEPTH DURING PANEL EXCAVATION
- 6. TRENCH EXCAVATION • INNORMAL SOIL CONDITIONS EXCAVATION IS DONE USING A CLAM SHELL OR GRAB SUSPENDED BY CABLES TO THE CRANE • THE GRAB CAN EASILY CUT THROUGH SOFT GROUND • IN CASE OF ENCOUNTERING BOULDERS A GRAVITY HAMMER(CHISEL) IS USED TO BREAK THE ROCK AND TAKE THE SPOIL OUT USING THE GRAB
- 7. EXCAVATION SUPPORT:- • THESIDES INSIDE THE TRENCH CUT CAN COLLAPSE EASILY • BENTONITE SLURRY IS USED TO PROTECT THE SIDES OF THE SOIL • BENTONITE IS A SPECIALLY SELECTED FINE CLAY,WHEN ADDED TO WATER FORMA AN IMPREVIOUS CAKE LIKE SLURRYWITH VERY LARGE VISCOSITY • THE SLURRY WILL PRODUCE A GREAT LATERAL PRESSURE SUFFICENT ENOUGH TO RETAIN VERTICAL WALL
- 8. REINFORCEMENT:- • REINFORCEMENT ISINSERTED IN THE FORM OF A STEEL CAGE,BUT MAY BE REQUIRED TO LAP A FEW SECTIONS IN ORDER TO REACH THE REQUIRED LENGTH
- 9. CONCRETING:- PLACING OF CONCRETEIS DONE USING TREMIEPIPES TO AVOID THE SEGREGATION OF CONCRETE AS CONCRETE BEING POURED DOWN, BENTONITE WILL BE DISPLACED DUE TO ITS LOWER DENSITY THAN CONCRETE BENTONITE IS THEN COLLECTED AND REUSED
- 10. PROCEDURE:- • THE EXCAVATIONIS CARRIED OUT USING A HEAVY SELF GUIDED MECHANICAL GRAB SUSPENDED FROM A LARGE CRAWLER CRANE • THE DIAPHRAGM WALLS WERE EXCAVATED AND CONSTRUCTED IN DISCRETE PANELS OF BETWEEN 2.8M AND 7.0M LENGTHS • AS THE EXCAVATION PROCEEDS, SUPPORT FLUID WAS ADDED INTO THE EXCAVATION TO MAINTAIN THE STABILITY OF THE SURROUNDING GROUND AND TO PREVENT A COLLAPSE. THIS FLUID IS CALLED “BENTONITE” OR “SLURRY”, WHICH IS A POSER MADE OF A SPECIAL TYPE OF SOLUBLE CLAY AND IS MIXED AT THE MIXING PLANT WITH POTABLE WATER • WHEN THE EXCAVATION IS COMPLETED, THE REINFORCEMENT CAGE WILL BE LOWERED AND THE CONCRETE PROCEDURE WILL BEGIN
- 11. JOINING FOR THEDIAPHRAGM WALL PANEL • DIAPHRAGM WALL CANNOT BE CONSTRUCTED CONTINUALLY FOR A VERY LONG SECTION DUE TO LIMITATION AND SIZE OF THE MECHANICAL PLANT • THE WALL IS USUALLY CONSTRUCTED IN ALTERNATIVE SECTION • TWO STOP END TUBES WILL BE PLACED AT THE ENDS OF THE EXCAVATED TRENCH BEFORE CONCRETING • THE TUBES ARE WITHDRAWN AT THE SAME TIME OF CONCRETING SO THAT A SEMI-CIRCULAR END SECTION IS FORMED • WALL SECTIONS ARE FORMED ALTERNATIVELY LEAVING AN INTERMEDIATE SECTION IN BETWEEN. THE IN-BETWEEN SECTIONS ARE BUILT SIMILARLY AFTERWARD BUT WITHOUT THE END TUBE
- 12. • AT THEEND A CONTINUAL DIAPHRAGM WALL IS CONSTRUCTED WITH THE PANEL SECTIONS TIGHTLY JOINED BY THE SEMI-CIRCULAR GROOVE
- 13. TYPES OF DIAPHRAGMWALLS:- STRUCTURAL DIAPHRAGM WALLS: THEY ARE USED AS RETAINING WALLS FOR THE PERIMETER WALLS OF DEEP BASEMENTS AND UNDERGROUND PARKING FACILITIES AND SUBWAYS LOAD BEARING WALLS: THEY ARE USED IN PLACE OF DRILLED PIERS IN FOUNDATION OF TALL BUILDINGS, BRIDGE AND PIERS CUTOFF WALLS: IN HYDRAULIC STRUCTURES DIAPHRAGM WALLS ARE USED AS IMPERMEABLE CUTOFFS TO PREVENT SEEPAGE BELOW EARTH DAMS AND WEIRS
- 14. EQUIPMENT USED FOR CONSTRUCTION:- •TERNCH CUTTR • HYDRUALUIC GRAB • REVERSE MUD CIRCULATION RIG
- 15. CONSTRUCTION SEQUENCE:- • CONSTRUCTIONOF GUIDE WALL • TRENCH EXCAVATION • SLURRY CLEANING • REINFORCEMENT CAGE LOWERING • CONCRETING
- 16. SLURRY CLEANING:- • DURINGEXCAVATION PROCESS THE MUD OR SOIL WHICH IS EXCAVATED OFTEN MIXES WITH THE BENTONITE SLURRY AND AFFECTS ITS PH, VISCOSITY, DENSITY ETC. • TO BRING ALL THESE PARAMETERS IN ACCEPTABLE LIMITS THE BENTONITE SLURRY IS CONTINUOUSLY CIRCULATED THROUGH BENTONITE PLANT WHICH CLEANS THE SLURRY AND RESTORES ITS REQUIRED PROPERTIES • THE SLURRY IS CLEANEDN USING THE MACHINE BY REVERSING CIRCULATING MUD MACHINE
- 17. ADVANTAGES OF DIAPHRAGMWALL:- • SUITABLE FOR UNSTABLE SOIL PROFILES BELOW WATER TABLE • LIMITED CONSTRUCTION TIME • WHERE DEEPER THAN NORMAL CANTILEVER SUPPORT MAY NEEDED. • DESIGNABLE TO CARRY VERTICAL LOADS • CONSTRUCTION TIME OF BASEMENT CAN BE LOWER • MINIMIZE THE SETTLEMENT OF ADJACENT BUILDING • IT IS THE PERMANENT BASEMENT WALL • IT IS USED AS A SUPPORTING WALL FOR DAMS • AND STOPS THE SOIL CREEP
- 18. • DEEPEST DIAPHRAG WALL INTHE WORLD IS CONSTRUCTED IN CAIRO IT IS 250 METERS DEEP AND 30 METERS WIDE AND 87.3 METERS LONG
- 19. • LONGEST DIAPHRAGM WALLIN THE WORLD IS CONSTRUCTED FOR POLAVARAM ITS LENGTH IS 1750 METERS LONG AND DEPTH OF 30 METERS AND WIDTH 1.5 METERS
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- 21. VEDIO SHOWING CONSTRUCTIONOF DIAPHRAGM WALL:-
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