Ground Improvement - PowerPoint Presentation

Slide1

Ground Improvement and Ground Control including Waste Containment with Geosynthetics

Dr. J.N.Jha,

Professor

and Head (Civil Engineering),

Guru

Nanak Dev Engineering College, Ludhiana, Punjab-141006Slide2

Ground Improvement Tehnique: Issues, Methods and their SelectionSlide3

Present Day Scenario

Best

buildable lands

not available for construction

Available sites are having low strength because :

Filled

up sites,

L

ow

lying water logged,

Waste

lands,

Creek

lands with deep deposits of soft saturated marine

clays

Another problem

:

Design

loads are high and the site is situated in seismic

zonesSlide4

What are the options?

Traditional

foundation techniques

sometimes costlier

than the super structure and in many situations

can’t

be

built

when

a

poor ground

exists

at the project site,

designer

faces

following

questions:

Should the poor ground be

removed and replaced

with a

more

suitable material?

Should the

weak ground be bypassed

laterally by

changing

the project’s location or vertically by the use of

deep

foundations? or

Should the

design of the facility

(height, configuration,

etc

) be

changed

to reflect the ground’s limitations?Slide5

Development of ground improvement,

gives the

designer/bulder has a

fourth option

To

“fix” the poor ground and make it suitable for the project’s

needs

Now the designer/builder

faces new questions

:

Should the

problematic ground

at the project site be

fixed

instead of

bypassed

?

What are the

critical issues

that influence the successful

application

of a specific fixing tool? And

Which

fixing tool

to

be used

from

comprehensive

and

diversified

set currently available

in

the tool box

?Slide6

What are the major functions

of Ground

improvement in

soil ?

To

increase the bearing

capacity

To

control deformations and accelerate

consolidation

To

provide lateral

stability

To

form seepage cut-off and environmental

control

To

increase resistance to

liquefaction

Above functions

can be accomplished

:

by

modifying the ground’s character

- with

or without the addition of foreign materialSlide7

The current state of the

practice:

Densification

Consolidation

Weight reduction

Reinforcement

Chemical treatment

Thermal stabilization

Electrotreatment

Biotechnical stabilization

Slide8

Ground Improvement by Densification

Methods of

Application :

Vibrocompaction

Dynamic Compaction

Blasting

Compaction

Grouting

Key

Issues affecting densification:

Percent

of fines in the soil,

Ability

of the soil to dissipate excess pore water pressure,

Energy

felt by the soil,

Presence

of boulders, utilities and adjacent structures, and

Mysterious

phenomenon of ageing.Slide9

Ground Improvement by Consolidation

Methods of

application:

Preloading

with or without vertical drains

Electro-osmosis

Vacuum

consolidation

Key

Issues associated with consolidation:

stability

during surcharge placement

,

clogging

of vertical drains, and

maintenance

of the vacuum.Slide10

Ground Improvement by Weight Reduction

Methods of

Application:

Placing lightweight materials over

the native soil in one of three ways

:

spread in a loose form, then compacted

cut in block forms, then stacked according to a

certain

arrangement, or

pumped in a flowable liquid form

key

issues with the weight reduction

method

Placement

of the lightweight material,

Longevity

and long-term performance.Slide11

Ground Improvement by Reinforcement

Methods

of

Application:

Mechanical

stabilization

Soil nailing

Soil anchoring

Mirco piles

Stone columns

Fiber

reinforcement

Key Issues Affecting Soil Reinforcement:

Load

transfer to the reinforcing elements

,

Failure

surface of the reinforced soil mass,

Strain

compatibility between the soil and the reinforcement,

Arrangement

of the reinforcing elements,

Durability

and long-term behavior of the reinforcements.Slide12

Ground Improvement by Chemical Treatment

Methods of

Application:

Permeation

grouting

Jet grouting

Deep soil mixing

Lime columns

Fracture

grouting

Key Issues involved in Chemical Treatment

soil-grout

compatibility and reactivity

,

operational

parameters

,

column

verticality, and

weathering

effectsSlide13

Ground Improvement by Thermal Stabilization

Methods of

Application:

Ground freezing

Vitrification

Key Issues of thermal stabilization

Degree

of saturation of the soil,

Rate

of groundwater movement,

Creep

potential of the frozen ground,

Post

thawing behavior,

Heat

transfer in the melted soil and

Impact

of heat on utilities and adjacent structures.Slide14

Ground Improvement by Electrotreatment

Methods of

Application:

Electrokinetic

remediation

Electroheating

Electrokineting fencing

Bioelectrokinetic

injection

Key Issues

in

Electrotreatment

Soil’s

electrical conductivity,

Ionic

characterization of the contaminants,

and

Impact

on buried objects and utilitiesSlide15

Ground

Improvement by Biotechnical Stabilization

Methods of

Application:

Brush layering

Contour wattling

Reed-trench layering

Brush matting

Live

staking and

others

key issues affecting biotechnical stabilization

Development

of artificial cohesion in the ground,

Effects

of evapotranspiration, and

Durability

of the vegetationSlide16

Factors affecting the selection of a ground improvement method

Ground

,

Groundwater

Construction

considerations including schedule, materials, accessibility,

right-of- way, equipment

and

labor

(d) environmental concerns,

(

e) durability, maintenance and operational

requirements

(f) contracting, politics and tradition,

(

g) costSlide17

Waste Containment with Geosynthetics

Large quantities of waste are being produced

since

1990

due to Rapid industrialisation and

Excessive urbanisation

Waste needs to be disposed off and only disposal

bin is ground and it occupies large chunk of land.

One million ton of municipal solid waste

occupies approximately one million square meter

(One square kilometer of land area when waste is

spread uniformly with a thickness of one meter)

Slide18

Other problem associated with waste disposal

Another problem with the disposal of waste :

Source of pollution

Contaminates the soil beneath the waste

Contaminates the ground water as

contaminants travel from the solid waste to

the subsurface environmentSlide19

Other sources of subsurface contamination

Ponding

or impoundment of Liquid Waste :

Slurry type liquid waste

Leakage from storage of liquids in underground

tanks

Leakage from pipelines that transport liquid

Accidental spills of toxic liquid

Application of fertilizers , pesticides on large

agricultural areasSlide20

How to tackle and minimise this damage

Design and implementation of solution for

detection, control, remediation and prevention of

subsurface contamination

Protection of uncontaminated land

Analysis of the fate of contaminants on and in

the ground including transportation through

geomedia

Use of waste material on and in the ground for

geotechnical construction Slide21

Pollution:MSW/ISW

Municipal solid waste/Industrial solid waste place on the

ground: two most significant source of subsurface

contamination

Water infiltrates into waste and reacts physically,

chemically and biologically to produce leachate

Leachate infiltrates into the ground causing subsoil and

ground water contamination

Solid waste continues to stay at the location where it is

placed for years

Therefore the process of leachate infiltration into

subsurface environment continues , slowly but surely for

several yearssSlide22

Control and Remediation

Clean up of soil involves - Treatment of three phases in soil:Solid soil particle, Liquid pore fluids and Pore gases

Methods

Controlling the spread of polluted zone by installing impermeable vertical barriers (cut-off walls) all around and horizontal cover above the contaminated site

Removing the source of contamination and placing it in designed facility

Excavating the affected soil, washing it or teating it and placing it back after treatment Slide23

Pumping out the contaminated ground water by using a

set of tube wells installed in the

Contaminated zone , treating the ground water and the

injecting the purified waterback (Pump and Treat

Method)

Pumping out pore gas from the unsaturated zone using

gas wells and allowing air to enter through injection

wells

Using micro-organism to biomediate the sub soil and

ground water by transforming or immobilzing the

contaminants

Using thermal treatment e.g. incineration

Slide24

Control of subsurface contamination for new facility

For solid waste: Providing impermeable flexible liners at

the base and covers on top of all Solid waste disposal

facilities to minimize leachate formation

For slurry type waste: Providing storage in ponds and

impoundments having incrementally raised

embankments and impermeable flexible liners at the base

For liquid: providind storage in ponds with impermeable

flexible liner

For underground liquid storage facility: Providing

double walle tanks with leakage detention system placed

between the walls Slide25

Thankyou...............