vertical drain group

8/7/2019 Vertical Drain Group

http://slidepdf.com/reader/full/vertical-drain-group 1/21

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



5W1H

WHAT?

WHY?

WHERE?

WHEN?

WHO?

HOW?



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



VERTICAL DRAIN



PREFABRICATED

VERTICALDRAIN (PVD)

A band-shaped(rectangular crosssection) consist of synthetic

geotextile ´jacketµ sorrounding aplastic core

Function of drain jacket

Function of drain core



Different types of

prefabricated verticaldrains (PVD)



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.



Preloading of subsoil

without vertical drains

Preloading with verticaldrains



RESULT EXAMPLE :TIME VS % CONSOLIDATION



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



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.



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.



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.



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



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.



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.



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.



Q& A

vertical drain group

Documents