Wash boring

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https://www.machenlink.com/course/foundation-engineering/

Description

Wash boring is a fast and simple method for advancing holes in all types of soils.

Boulders and rock cannot be penetrated by this method.

The method consists in first driving a casing through which a hollow drill rod with a sharp chisel or chopping bit at the lower end is inserted.

Water is forced under pressure through the drill rod which is alternately raised and dropped and also rotated.

The resulting chopping and jetting action of the bit and water disintegrate the soil.

The cutting is forced up to the ground surface in the form of soil − water slurry through the annular space between the drill rod and the casing.

The change of soil stratification could be guessed from the rate of progress and the colour of wash water.

The samples recovered from the wash water are almost valueless for interpreting the correct geotechnical properties of soil.



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1. FOUNDATION ENGINEERING
WashBoring

2. MachenLink
WASH BORING
•Washboringisafastandsimplemethodforadvancingholesinalltypesofsoils.
•Bouldersandrockcannotbepenetratedbythismethod.
•Themethodconsistsinfirstdrivingacasingthroughwhichahollowdrillrodwithasharpchiselorchopping
bitatthelowerendisinserted.

3. MachenLink
Derrick,
4 –legs of pipe
Pump
Rope
Swivel
WASH BORING
Tub
Wash pipe (drill rods)

4. MachenLink
Derrick,
4 –legs of pipe
Pump
Rope
Swivel
WASH BORING
Tub
Wash pipe (drill rods)

5. MachenLink
WASH BORING
Drilling Bit
Wash pipe (drill rods) •Waterisforcedunderpressurethroughthe
drillrodwhichisalternativelyraisedand
droppedandalsorotated.
•Theresultingchoppingandjettingaction
ofthebitandwaterdisintegratesthesoil.
•Thecuttingareforceduptotheground
surfaceintheformofsoil−waterslurry
throughtheannularspacebetweenthedrill
rodandthecasing.
•Thesamplesrecoveredfromthewashwaterare
almostvaluelessforinterpretingthecorrect
geotechnicalpropertiesofsoil.
•Thechangeofsoilstratificationcouldbe
guessedfromtherateofprogressandthe
colourofwashwater.
Chopping bit, replaced by
sampling spoon during
sampling operations