bapatla vasu ppt

8/12/2019 Bapatla Vasu Ppt

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A TECHNICAL PAPER PRESENTATION

ON..

Practical applications of ground

improvement techniques

Presented by:

D.VasanthiCh.Namratha

11481A0122

11481A0118

III B.tech CEIII B.tech CE

Mail

id:dagguasanthi!gmail.

c"m Mail id:namrathcha##idi!gmail.c"m

$egistrati"n.N":%t1000888 $egistrati"n.N":1000&'(

DEPARTMENT OF CIVIL

ENGINEERING

)*D+AVA++E$* EN)INEE$IN) C,++E)E-

GUDLAVALLERU.


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bydeepvibrationb$Improvementbyincreasingeffective

stresses c$Improvementbyreinforcementd$Improvem

entbystructura

lfillse$


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Improvem

entbyadmixturesf$Improvement

bygroutingg$Improvement bythermalstabili!ati

on, etc.

%ased on the soil conditions, a suitable method of ground improvementshould be considered &eeping in view of the economic feasibility as well asthe time frame. In practice, ground improvement is widely used in a broadconstruction spectrum from industrial, commercial and housing proects toinfrastructure construction for dams, tunnels, ports, roadways andemban&ments. This paper presents four different ground improvementtechniques along with a case history for each of the technique as anexample.


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"Prac

ticalApplicati

ons

'.( GroundImprovement )sing*ibro compaction

+once

ptof*ibro+omp

action

"articles of granular soil can be rearranged by vibration in such a way thatthey obtain a higher density. In non cohesive soils granular soils$, theeffective depth of surface compactor and vibratory roller is limited to a fewmeters below ground level and the larger depths can be reached by


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deep compaction methods using depth vibrators. The method is referred as*ibro compaction.

The depth vibrator is lowered into the ground under its own weightassisted by water flushing from ets positioned near the tip of the vibratori.e. bottom ets$. -xperience has shown that penetration is most effective ifa high water flow rate is used, as opposed to high water pressure. nreaching the designated final depth, the bottom ets are closed and flushing

continued by water from ets positioned near the top of the vibrator. Theseets direct water radially outward, assisting the surrounding sand to fall intothe space around the vibrator.

The vibrator is maintained at the final depth until either the powerconsumption of the vibrator reaches pre determined amperage or thepreset time intervals have elapsed, typically 01231sec, whichever is thesooner. 4hen the amperage/time criterion is satisfied, the vibrator is raisedto a predetermined height, typically 1.52

(.1m, and again is held in position for the preset time or until the amperagereaches the target level, whichever is sooner. The vibrator is then lifted forthe next compaction step and this procedure continues stepwise until thevibrator reaches the surface.

6s a result of *ibro compaction, the occured settlement may range between57 to (57 of the compaction depth depending on the original densityand the desired density. 6 schematic showing the stepwise installation

process of *ibro compaction is shown in 8igure (. 4hen *ibro compactionis used for large areas, it is typically performed using either a triangular orrectangular grid pattern with probe spacing in the range of 'm to 9m c/c.The spacing depends on several factors, including the soil type, bac&filltype, probe type and energy, and the level of improvement required.

8igure (. Istallation sequence of *ibro +ompactionprocess

:u


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ality+ontrol;:uality

6ssurance

In general, quality management of *ibro compaction wor&s are divided intotwo categories, namely monitoring of compaction parameters and postcompaction testing. The compaction parameters depth and powerconsumption$ are monitored using realtime computerised systemthroughout the construction process. The recorded data also printedsimultaneously in realtime along with the probe reference number, dateand time of compaction. This ensures proper documentation of the wor&done in order to verify desired end product is acheived.

"ost compaction testing is performed to ensure that the specifications aremet. Typically, sounding methods are used to assess the effectiveness ofthe *ibro compaction. Dynamic penetrometer tests D"T$, standardpenetration tests


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ibro+ompaction

*ibro compaction is used to increase the bearing capacity of foundationsand to reduce their settlements. 6nother application is the densification ofsand to mitigate the liquefaction potential in earthqua&e prone !ones. *ibrocompaction may be used as a ground improvement technique to support alltype of structures from emban&ments to chemical plants. The use of vibrocompaction mainly depends on the type of granular soil to be compacted.Depths down to 35 m have been improved so far by using *ibro compactiontechnique.

=imitations

*ibro compaction methods are most effective for sands and gravels with less

than about (5 to '1 percent fines as shown in 8igure '. *ibro compaction

wor&s performed for an oil storage terminal is presented below for better

understanding of the technique and it>s performance


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8igure '. 6pplicable soil types for *ibro +ompaction

and *ibro ?eplacement

'.(.( *ibro +ompaction for )niversalTerminal at @urong Island,


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storage facility, consists of A0 tan&s, ranging in diameter from (0.3m toAB.3m and having heights between (5m and ''.0m refer to 8igure 0$. TheA0 tan&s are divided into (' tan& farms. It also includes valve manifolds,pump stations and other ancillary facilities.

8igure 0. 6rtist impression of the)niversal Terminal upon

completion

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