IPT EXPERIENCE

Presented by

Leena Pauline A.

Sindhana Roy J.

HARBOUR

Any part of a body of

water and the man-made structures surrounding it, that sufficiently shelters a vessel from wind, waves and currents, enabling safe anchorage or the discharge and loading of cargo and passengers is called Harbour.

Model of tuticorin harbour

BREAK-WATERS:

The function of breakwaters is to absorb or throw back as completely as possible, the energy content of maximum sea waves assailing the coast.

Inner mould - Small rocks or rubbleOuter covering - Large boulders

These are built with an aim in achieving the minimum initial capital coat, without incuring excessive future commitments for maintenances.

DOCKS AND QUAYS:

The principal operation to which harbour works are dedicated is ‘transfer of goods from one transportation to another(eg. From ships to trucks)

The station point of the vessels is called “Berth”

So docks, wharves and quays are the most important assets of a port. Ships must lie afloat in complete shelter within the reach of mechanical devices for discharging their cargoes.

Large areas of firm, dry land, immediately alongside the ship is required.

It is essential that the engineers must find a way to support this land and any superimposed loading it may carry.

In such cases retaining walls are used.

The solution initially favoured and indeed predominant for many years was that of the simple gravity retaining wall, capable of holding land and water apart.

In olden days many projects were carried out in open excavation usind temporary cofferdams to keep out the water.

So, in particularly unfavourable or unstable soils, accidents caused by collapse of excavation were not known.

In modern practice, no project is initiated without extensive exploration of the soil conditions.

Continuous monitoring of the soil conditions during construction is also essential.

The material composing the wall today is almost universally palin or reinforced concrete.

In olden days heavy ashlar(natural rock) masonry was used.

RETAINING STRUCTURES:All civil engineering structures are impose upon or supported by mother earth.

It is a two way interaction – Soil-structure interaction(SSI).

The SSI effect is reasonable for light structures in relatively stiff soil like low rise buildings and simple rigid retaining walls.

It is prominent for heavy structures resting on soft soils.

Retaining structure is a prime example of SSI

In all discussions about the development trajectory of India, maximum attention is paid to infrastucture deficiency.

Sharpest focus is on transport and power – twin engines of growth across all sectors of economy.

Retaining structures are engineered to retain soil or rock from an area, building or structure.

They prevent the downslope movement or erosion and provide support for vertical or near vertical grade changes.

They are made of masonry-stone, brick, concrete, vinyl, steel or timber.

Segmental retaining walls have gained favour over poured-in-peace concrete walls or treated-timber walls.

TYPES OF RETAINING STRUCTURES:GRAVITY-STANDARD WALL TYPE: It holds the earth mainly due to its own weight and usually made from heavy materials like concrete.

It will topple relatively easily as the internal leverage of the earth pressure is very high.

SHEET PILE: Using long piles, this wall is fixed by soil on both sides of its lower length and typically consists of steel sheet piles that are driven into the ground to support pressures.

If the piles themselves resist the bending forces, this wall can take high loads.

CANTILEVER: It is shaped like an inverted T and is typically made from a thin stem of steel-reinforced, cast in place concrete.

The pressures from the retained soils or rock are carried through the stem to the structural footing(bottom of the T) are transferred to the soils below.

ANCHORED: This wall keeps itself from toppling by having cables driven into the soil or rock, fixed by expanding anchors and mechanically stabilized walls.

This can be combined with other types of walls.

RETAINING STRUCTURES FOR WATER RESOURCES AND IRRIGATION:

India is an agricultural land and therefore Indian economy depends upon agriculture to a vast extent.

45 million hectares of agricultural land is to be irrigated.

This is to be achieved by devising efficient storage and distribution systems.

Therefore new technological innovations are brought to play.

Effort is to design the projects for multipurpose usage, to get the maximum benefit from the same water resource.

USES - WATER RETAINING STRUCTURES:

Examples: dams, barrages, tunnels, surge shafts, power houses, regulators, aqueduct, channels etc. – retaining structures for hydropower projects and irrigation schemes.

In addition to the above 2 major uses, they also help in flood mitigation by creating reservoirs.

PILING:

A long slender column, usually of timber, steel or reinforced concrete, driven into the ground to carry a vertical load is termed as a ‘pile’.

NEED FOR PILING:

The high cost, difficulties and possible dangers of providing dock and quary walls have always encouraged a search for alternative solutions, that would eliminate the need for operations on or below the sea bed.

The earliest and most obvious alternative method is piling.

The piles can be driven from floating craft and the deck and super structure added thereto working wholly above water.

With a reasonable planning of the work, this operation can usually be done without particular difficulty.

It can be conveniently assumed that the sea bed is of a composition reasonably amendable to penetration by piles to a sufficient depth to secure the lateral stability of the structure.

Hard rock is not suitable, although some of the rocks can be pierced by steel piles.

Piles may be of timber, reinforced concrete or steel.

Timber is a popular choice if there is a large scale natural supply.

Lateral stiffness and stability can be achieved by using a sufficiently close spacing of the piles in both directions and adequate rigid bracing between the tops.

Timber jetties have a considerable advantage in the comparitive ease with which, repairs to accident damage or deterioration can be effected.

Its chief drawback is the lack of durability, particularly in the area between wind and water.

Reinforced concrete piled piers and jetties, soundly constructed, exhibit great durability.

There are examples of construction in which the piles are connected together by casting a reinforced concrete slab around the heads, its underside just below lowest water level.

Attachment to the piles for bracing and similar purposes tends to be more complicated than in the case of timber.

CLASSIFICATION OF PILES:

Piles may be classified on

the following basis

i) Based on materials and

composition

ii)Based on function or use

CLASSIFICATION BASED ON FUNCTION:

Based on the function or the use, piles may be classified as:i)End bearing pilesii)Friction pilesiii)Compaction pilesiv)Sheet pilesv)Batter pilesvi)Under-ream pilesvii)Fender pilesviii)Tension or uplift piles

COMPACTION PILE

FENDER PILE:

SHEET PILE:

PILING EQUIPMENTS:

BORED CAST IN-SITU CONCRETE PILES:

The process of construction of a bored cast in-situ pile consists of 4 steps:a) Drilling of holeb) Stabilization of holec) Placement of reinforcementd) Concreting

In soil, that is dry or moist and does not require stabilization, drilling with an auger is effective. A casing is installed in soils requiring side support during drilling operation.

In very soft soils, where the drill tool cannot operate ahead of the casing, the casing may be pushed into the soil and a grab is used to remove the soil from inside the casing.

Then, the hole is stabilized with continuous slurry circulation. That also carries away the soil drilled using a chisel type percussion tool. This technique is referred to as the direct mud circulation technique of drilling.

The Bentonite slurry travels through the drill stem to the base of the hole and moves up carrying the soil cuttings loosened by the up-down motion of the cutting tool.

The slurry is recirculated after allowing the soil cutting to settle in a pond. The slurry density of 10.5 to 12kN/m³ ensures stability of the hole.

Concreting is carried by a technique called tremie concreting that was developed for underwater operations.

The concrete is sent down a tremie pipe to gradually displace the Bentonite slurry from the hole.

The concreting operation requires care and skill.

Two factors are important during concreting.

First, the concrete should fall through the tremie pipe as though it were a solid mass to displace the Bentonite slurry. Second, the base of the tremie pipe rust remain embedded to sufficient length in the concrete to prevent the Bentonite slurry from re-entering the pipe.