Vertical Drain Group
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Transcript of Vertical Drain Group
8/7/2019 Vertical Drain Group
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FACULTY OF CIVIL AND ENVIROMENTAL ENGINEERING
GEOTECHNICS PROJECT
UNIVERSITI TUN HUSSEIN ONN MALAYSIA (UTHM)
86400 PARIT RAJA, BATU PAHATJOHOR, MALAYSIA
GROUP MEMBERS:
1. MUHAMAD TAUFIK@ADAM B ABD RASHID
2. MOHD SHAUTI BIN GHAZALI@MOHD ZAIN
3. FARAH SOFHIA BINTI MOHD ZIN
4. RAJA JULALI BINTIRAJA ALI
5. AMIRAH SILMI BINTI AHMAD SHAKRI
LECTURER:
MR. KHAIRUL NIZAR BIN YUSOF
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5W1H
WHAT?
WHY?
WHERE?
WHEN?
WHO?
HOW?
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WHAT
VERTICALDRAIN
artificially-created drainage pathswhich are inserted into the soft
clay subsoil
well, pipe, pit, or bore inporous, underground
strata into which drainage water can be discharge
without contaminating anygroundwater resources
TYPES :1)sand drains
2)fabric encased sand drains
3)prefabricated sand drains
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VERTICAL DRAIN
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PREFABRICATED
VERTICALDRAIN (PVD)
A band-shaped(rectangular crosssection) consist of synthetic
geotextile ´jacketµ sorrounding aplastic core
Function of drain jacket
Function of drain core
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Different types of
prefabricated verticaldrains (PVD)
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WHY
� to shorten theconsolidation time
� to accelerate theconsolidation process of the clay subsoil
� to gain rapid strengthincrease to improve thestability of structures onweak clay foundation.
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Preloading of subsoil
without vertical drains
Preloading with verticaldrains
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RESULT EXAMPLE :TIME VS % CONSOLIDATION
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WHEREType of
soil
Cohesive, fine grained soils,either organic or inorganic
inorganic silts & clays ,organic silts
&clays,decomposed peat or
´muckµ
PV drains not appropriate inhighly pervious or granular
soils.
SoilCharacteristics
Moderate to highly compressibleunder static loading
Compress very slowly under naturaldrainage system due to low soil
permeability
Relatively great distance between naturaldrainage boundries
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WHENWHEN IS THE INSTALLATION OF THE
VERTICAL DRAIN
o Before infrastructure or buildings
were develop in any area.
-It is necessary that the ground upon which thedevelopment is to take place adequately
consolidated in order to take the load of the
infrastructure or building.
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o W hen the area has a weak soil.
(Silt And Clay)
-This is especially where construction is to take
on reclaimed land.
-Large amounts of clay, silty and marine clay
are to be found in many areas inland and onshore
where land is to be reclaimed.
-These weak soils have a high water content
which must be reduced so that the ground can
consolidate before construction take place.
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WHO
CONTRACTOR ENGINEER
THE APPROVAL
� Four weeks prior to the
beginning of trial PVD
installation, the Contractor
shall submit full details of the
materials, equipment,
sequence and method
proposed for PVD installation
to the Engineer for review
and approval.
� Approval by the Engineer of
the method or equipment
used to install the trial drains
shall not constitute,
necessarily, acceptance for
the remainder of the project.
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HOWHOW DOES VERTICAL DRAINAGE WORK
Prefabricated vertical drains consists of a composite
strip with a corrugated core wrapped in apermeable filter slieve.
The corrugation of the core allow the pore water toflow to the surface whereas the slieve prevents thesoil from blocking the core channels.
The cross-section dimensions of the strip are 100mm by 4 mm and the drains are delivered on rollsof250 to 300 m length.
The rolls are mounted on the installation rigs onsite for installation
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The PVD are installed into the soil with aspecial installation rig in a triangular gridof 1 to 2 metre spacing.
The drain is inserted into the compressiblesoil to the prescribed depth.
Immediately after installation the drainstarts to wick the pore-water to the surfacewhere it evaporates or flows away.
The pore-water tension is dissipated and
settlement of the ground enhanced
The result is an accelerated consolidation of the ground.
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HOW IS PVD INSTALLED
PVD may be installed employingeither vibratory or static crowdmethods.
In either case, the drain is enclosedin a tubular steel mandrel of smallcross-sectional area usually 2 x 5inches(50 x 125mm).
A small steel anchor plate isattached to the drain at the bottomof the mandrel.
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The mandrel is then driven in tothe soil either with a static crowdor vibratory rig
When the design depth is reached,the mandrel is extracted.
The anchor plate retains the drain inthe soil.
When the mandrel is fully extracted,the drain is cut off, a new anchorplate is installed and the processbegins again.
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Q& A