JETTIES, WHARVES & PIERS

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JETTIES,WHARVES & PIERS

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INTRODUCTION

The units at a port that helps the process of

loading & unloading of cargo & passengers are:

Fixed units:

In the form of stationary platforms known as

Jetties, Wharfs & Piers

Movable units:

In the form of Cranes, Conveyors, Escalators,

Vacuum pumps etc 2


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JETTIES

Structure in the form of piled projections

Built out from the shore to deep water

Berth on one or both sides & sometimes at the end.

Constructed of steel, concrete or rock.

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Contd. Should be suitably located w r t prevailing

currents Should be designed to resist berthing impact of

vessels Jetty face should be with a cushion ,fender

Jetties are constructed either in the sea or river In rivers, scouring action is prevented by

diverting current from bank & navigation is also

controlled. In the sea, the jetties are provided where theharbour entrance is affected by littoral drift / thesea shallow for long distance.

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Contd.Exposed to severe wave action & the structural

design is similar to breakwater.Helps to prevent long shore drift & slow downshore erosion.Impact of berthing ships will depends on: skill ofberthing officer, local condition of currents, windetc.Berthing velocity depends on the condition of

approach ,wind etc & it decreases with increase inthe size of the ships.

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TYPES OF JETTIES

Depending on the method of construction

Cylinder type jetties

Screw piles & screw cylinder jetties

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CYLINDER TYPE JETTIES

Constructed with cast iron & reinforced concrete

cylindersCylinder of cast iron should have length not lessthan 5ftDiameter to ensure adequate working space up to6ftReinforced concrete cylinders should have a lengthof 5-6ft

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SCREW PILES & SCREW CYLINDER JETTIES

Suitable for situations in rivers and estuaries

where there is considerable depth of alluvialdepositsThese are of solid steel of either 6,8,10inchdiameter.Length 20-30ftJoined together in several ways.Essence of joint is to properly transmit the

screwing torque and to provide a sound andaxially true connection to sustain the vertical loadimposed on the pile.

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WHARVES

Landing places/platforms in the form of wallsbuilt near shore for vessels to berthIt may be a sheet pile wall, a piled projection or agravity wall

structure includes berths, piers, warehouses

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Parallel to shore & abutting against shoreLevel of wharf should be above high water levelShould properly braced and boltedIn case of large vessels provide rounded cornersThe type of vessels to be accommodateddepends on length of wharf & water depthSingle wharf with a single berthwherecapacity is sufficient

Multiple wharves - for more capacityPier, raised over the water is used where the

weight/volume of cargo is low.

Contd.

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Design of wharves involves these factors

Provision for berthing of ship

Handling and storage of cargo

Terminal facilities for rail & truck transportation

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DIFFERENCE BETWEEN WHARFS &JETTIES

Wharf is parallel to shore & jetty is perpendicular

to shore or breakwater

Wharf has berth on one side only but jetty mayhave berth on two faces

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PIERSStructure projected into ships basin at rightangles or oblique to the shoreConstructed with piles, columns and braces

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Piers consist of two partsThe floor

Made with timber for small piers & concreteor RCC for large piers

The supporting partIt include foundation and substructure

Foundation: raft foundation, stepped footingor pile foundationSubstructure: the supporting part between sea

bed to bottom of floor

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Design of piers involves these factors

The LL for pier design depends on nature ofanticipated cargo & shipping.No space for storing cargo.The horizontal thrust on pier head is taken as 1%

of the maximum weight of the vessel to beberthed.Water depth at the pier should provide a min of300mm clearance under the keel of a fully loadedship with reasonable provision for a low tide.

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Types of piers

According to the principal purpose

Working piers

Pleasure piers

Fishing piers

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Working piers

For handing passengers and cargoWorking piers are of two typesLonger individual piersFound at ports with large tidal rangesEconomical alternative to impounded docksFinger piersBuilt at ports with smaller tidal rangesGive a greater available quay length for ships to

berth against compared to a linear littoral quayside

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Pleasure piers

For tourists to promenade over and alongside thesea at all times.Include amusements and theatres as part of theattraction

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http://en.wikipedia.org/wiki/File:The_jetty,_Margate,_Kent,_England,_ca._1897.jpg


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Fishing piers

Many piers are built for the purpose of providingboatless anglers access to fishing grounds that areotherwise inaccessible

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Trestle pier

Substructure is totally framed & floor is of timbervertical and inclined bearing pilesbracing piles to connect bearing pilesFender piles to resist impact of vessels

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Types of trestle pier

Pier with central fill:

Substructure of trestle is partly coverd bydegraded materialsPier with central mound:Substructure of trestle is fully covered with

central moundIncreases strength of substructure

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REFERENCE

1. Text book of Harbour dock and tunnelengineering by R.Srinivasan

2. Web sources

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Thank you

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JETTIES, WHARVES & PIERS

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