civil SOIL LIQUEFACTION ppt.pptx

Soil liquefaction

1. www.studymafia.org Submitted To: Submitted By: www.studymafia.org www.studymafia.org Seminar On Soil Liquefaction

2. Content Key terms Soil Liquefaction Formal State of Soil Why Liquefaction occurrence….? What is Actually Liquefaction..? Why liquefaction important? Reference

3. Key terms SATURATED SOILS: SOILS IN WHICH THE SPACE (VOIDS) BETWEEN THE SOIL PARTICLES IS COMPLETELY FILLED WITH WATER PORE WATER PRESSURE: PRESSURE EXERTED ON PARTICLES OF SOIL BY THE WATER IN THE VOIDS.

4. SOIL LIQUEFACTION A SATURATED SOIL SUBSTANTIALLY LOSES STRENGTH AND STIFFNESS UNDER EFFECT OF EARTHQUAKE SHAKING AND OTHER RAPID LOADING . THE SOIL PARTICLES BECOME ‘ SUSPENDED ’ IN THE WATER. THE SOIL MOMENTARILY LOSE CONTACT AND SOIL BEHAVES AS LIQUID . BETTER KNOWN PHENOMENON “ QUICK SAND ” . RESPONSIBLE FOR TREMENDOUS AMOUNT OF DAMAGE IN HISTORICAL EARTHQUAKE AROUND THE WORLD.

5. FORMAL STATE OF SOIL DUE TO FORCE OF GRAVITY,SOIL PARTICLES “ NATURALLY ” RESTS UPON EACH OTHER. DEPENDING UPON THE PROPERTY OF SOIL,FORMS SORT OF GRID THAT IS RELATIVELY STABLE .

6. WHY LIQUEFACTION occurrence….? WATER PRESSURE BECOMES STRONG ENOUGH TO COUNTERACT THE GRAVITATIONAL PULL ON THE SOIL PARTICLE. EFFECTIVELY “ FLOAT ” OR “ SUSPENDS ” THE PARTICLES WITH RESPECT TO EACH OTHER.

7. WHAT IS ACTUALLY LIQUEFACTION..? SOIL GRAINS IN AN UNEXCITED, SATURATED SOIL DEPOSI T . FORCES CREATED BY THE INTERACTIONS OF THE SOIL GRAINS ELEVATED WATER PRESSURE CREATED BY ADDITIONAL LOADING : ” FLOAT ”

8. Niigata , japan THE PICTURE AT RIGHT SHOWS OVERTURNED APARTMENT BUILDINGS IN NIIGATA, JAPAN DUE TO LIQUEFACTION IN 1964.

9. Sand Boiling IF LIQUEFACTION OCCURS BENEATH A SURFACE THAT HAS HARDENED AS A RESULT OF COMPACTION, WEATHERING, OR SOME OTHER PROCESS; ‘ SAND BOILING ’ CAN OCCUR. Olympia, Washington, 2001

10. FIRST ORIGINATION THE TERM “ LIQUEFIED ” WAS FIRST USED BY HAZEN IN REFRENCE TO 1918 FALIURE OF THE CALAVERAS DAM IN CALIFORNIA. FOLLOWING WAS HIS DESCRIPTION “ IF THE PRESSURE OF THE WATERS IN THE PORES IS GREAT ENOUGH TO CARRY ALL THE LOADS,IT WILL HAVE THE EFFECT OF HOLDING THE PARTICLES APART AND OF PRODUCIONG A CONDITION THAT IS EQUIVALENT TO THAT OF QUICKSAND …THE INITIAL MOVEMENT OF SOME PARTS OF MATERIAL MIGHT RESULT IN ACCUMULATING PRESSURE,FIRST ON ONE POINT , AND THEN ON ANOTHER , SUCCESSIVELY , AS THE EARLY POINTS OF CONCENTRATION WERE LIQUEFIED .

11. What affects whether or not soil liquefaction will occur? GENERALLY, LIQUEFACTION WILL OCCUR IN LOOSE CLEAN TO SILTY SANDS THAT ARE BELOW THE GROUNDWATER TABLE BUT STILL CLOSE TO THE SURFACE OF THE DEPOSIT. LIQUEFACTION CAN ALSO OCCUR IN SOIL THAT IS COMPLETELY SUBMERGED AND COMMONLY CAUSES SIGNIFICANT DAMAGES TO BRIDGE FOUNDATIONS, OFF-SHORE OIL DRILLING FACILITIES, AND OTHER STRUCTURES THAT ARE SUPPORTED BY SUBMERGED SOIL DEPOSITS. PRIOR TO AN EARTHQUAKE, THE WATER PRESSURE IS RELATIVELY LOW . EARTHQUAKE SHAKING CAN CAUSE THE WATER PRESSURE TO INCREASE TO THE POINT WHERE THE SOIL PARTICLES CAN READILY MOVE WITH RESPECT TO EACH OTHER.

12. LAKE MERCED, CALIFORNIA, 1957 LIQUEFACTION CAN OCCUR EASILY ON RIVER BANKS AS WELL AS NEAR LARGER BODIES OF WATER

13. LIQUEFACTION OCCURENCE IN 1976 IN GUATEMALA ON THE MONTAGUA RIVER

14. Why liquefaction important? LIQUEFACTION IS RESPONSIBLE FOR EXTREME PROPERTY DAMAGE AND LOSS OF LIFE DUE TO A SEVERAL VARIATIONS OF FAILURE POTENTIAL. . LIQUEFIED GROUND IS NO LONGER STABLE TO WITHSTAND THE STRESSES IT IS SUBJECT TO FROM STRUCTURAL FOUNDATIONS OR EVEN ITS OWN WEIGHT, LEADING TO A VARIETY OF POTENTIAL FAILURES . THE BUILDING STRUCTURES WILL LEAN AND FALL ; OR AT TIMES EVEN SPLIT OPEN UNDER THE STRAINS.

15. UPPER DECK COLLAPSE OF BAY BRIDGE FROM SAN FRANCISCO, CALIFORNIA 1989,

16. Land sliding due to liquefaction OLYMPIA, WASHINGTON, 2001 THE STRESSES PRODUCED DURING LIQUEFACTION CAN CAUSE TENSION CRACKS TO FORM IN THE SOIL NEAR THE EMBANKMENT, OR IT CAN COLLAPSE ALTOGETHER , COMMONLY KNOWN AS LATERAL SPREADING OR LAND SLIDING .

17. How can the risk of damage due to soil liquefaction be reduced?   TO AVOID PLANNING DEVELOPMENT ON LIQUEFACTION SUSCEPTIBLE SOILS . BESIDES IN-SITU TESTING, VULNERABLE SITES CAN ALSO BE IDENTIFIED BY RESEARCHING ANY PRIOR EVENTS AT THE SITE. A STRUCTURE THAT INCORPORATES DUCTILITY , HAS SUPPORTS THAT ARE ADJUSTABLE TO ACCOMMODATE DIFFERENTIAL SETTLEMENT, POSSESSES THE ABILITY TO ACCOMMODATE LARGE DEFORMATIONS , AND HAS A FOUNDATION DESIGN THAT CAN SPAN ‘ SOFT ’ SPOTS, CAN ALL DECREASE THE AMOUNT OF DAMAGE INCURRED IN THE CASE OF A LIQUEFACTION EVENT.

18. EXAMPLE OF FOUNDATION DESIGN THAT SPANS OVER A SOFT SPOT DYNAMIC COMPACTION INJECTION & GROUTING STEPS CAN BE TAKEN TO IMPROVE THE SOIL CONDITIONS AND LOWER THE POTENTIAL FOR LIQUEFACTION OCCURRENCE

19. Reference www.google.com www.wikipedia.org www.studymafia.org

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