HARBOUR AND DOCK

ENGINEERING

Presentation 7Asnidha V, Asst. Prof, CE Dept. Mdit

Asnidha V, Asst. Prof, CE Dept. Mdit

Approach:

– path through which ship can enter the harbour safely.

Approach channel:

When sea around the harbour has depth less than draft

required for the largest ship visiting the harbour a separate

approach demarcated and dredged for required depth is

necessary.

Lock gates:

–When water level of sea around the port is varying to a

large extend

1. On leeward side - safe 2. On windward side

basinbasin

sea sea

Asnidha V, Asst. Prof, CE Dept. Mdit

1. Pointing down

stream3.Pointing upstream

• Not favorable

– Silt deposits

– Requires maintenance

dredging

Harbourbasin

Harbourbasin

Harbourbasin

2.Pointing midstream

• Difficulty in

maneuvering

Asnidha V, Asst. Prof, CE Dept. Mdit

• Depth – draft of largest ship

• Width – widest ship

• Length – type of entrance

• Tidal Entrances

– Entrance without gates

• Impounded Entrances

– Entrance with gates

I. Entrance with one pair of gates

a) Ebb gates

b) Storm gates or flood gates

II. Entrance with two or three pair of gates

1 a.Ebb gates

• Stop flow of water from

harbour during low tides.

• Entry of ship – only during

high water level.

1 b.Storm gates or flood gates

• Stop flow of water into the

harbour during flood

WL. In harbour is above L.W.L harbour

Asnidha V, Asst. Prof, CE Dept. Mdit

2.Entrance with two or three pair of gates

• Water level in lock

chamber can be

altered.

• Entry and exit of

ship takes more

time

seaW.L. =19.85m

Lock chamberW.L.= 18.95 m

harbour basin W.L. = 20.25 m

Asnidha V, Asst. Prof, CE Dept. Mdit

• Lock is a device for raising or lowering boats between stretches

of water.

• It is used to make river more easily navigable or to allow a canal

to take a reasonably direct line across land that is not level

Give access to docks

Consist of chamber, enclosed quay walls on each side

Paved at the bottom by an inverted arch flooring, to resist

upward water pressure, when dock level is low

Locks have two pairs of gates with a lock chamber in

between.

costly

• width varying from 25m and above

• depth 8m to 12m

• length 240m and above

• It may be wooden or iron

• Wooden gates consists of series of horizontal beams of green

heart

• Iron gates consists of plate iron ribs, covered with a skin of

iron sheeting

• Shape

– usually straight or curved

• Curved gate

– is strong against the transverse water pressure

–Curved gates are theoretically the best type

–But curved gates are longer and costlier

Asnidha V, Asst. Prof, CE Dept. Mdit

Support for lock gates

• Gate is fitted with a pivot cap at bottom of heel post

and an encircling anchor strap at the top

• Usually opened and closed, by two sets of chains,

one for opening and other for closing

• Chains are fastened at 1/3rd its height on both sides

• For small boat canal gates, lock gates can be

operated by hand

Asnidha V, Asst. Prof, CE Dept. Mdit

THANK YOU