Test: Docks, Harbours & Tunnel Engineering - 2 - Civil Engineering (CE) MCQ

Docks or wet docks or tidal basins are enclosed and are shut off by entrances or locks to maintain a uniform level of water and basins are partially enclosed areas of water. Dry docks are repair docks. These are long, excavated chamber, having side walls, a semi circular end wall and a floor, A floating dry clock is a floating vessel which can lift a ship out of water and retain it above water by means of its own buoyancy.

Groynes are structures built to protect beach or retard erosion of an existing or resorted beach by trapping of littoral drift. They are usually made perpendicular to shoreline.
Sea-walls, bulkheads and revetment are the structures constructed parallel to shoreline to develop a demarcating line between land area and water area.
Jetties are piled projection and they are built out from the shore to deep water. They are provided at places where harbour entrance is affected by littoral drift or the sea is shallow for a long distance.

Anchorage area is a place where ships may be held for quarantine inspection, await docking space or await favourable weather condition. The water area required for an anchorage depends upon number, type and size of vessels.
The anchorage area is calculated as the area of the circle having radius,
R = 4 x depth of water + length of ship + safe clearance to adjacent ship
= 4 x 15 + 181 + 12 = 253 m 
So area = πR² ≌ 20 ha

Berth is a facility where one vessel may be safely moored and load/unload cargo or let passengers or vehicles embark or disembark.

Components of a shield are hood, tail, cutting edges, propelling jacks.

Spring tides occur usually at new and full moon or rather a day or two after (or twice in each lunar month). At new moon, the sun and moon have the same celestial longitude and cross a meridian of the earth at the same instant. The sun and moon are on same side of the earth. The high water level of the resulting tide is above the average, whereas the low water level is below the average.
During neap tide, the moon falls behind the sun. High water level is below the average, whereas the low water level is above the average.

Size of shaft depends upon the following factors:
(i) Quantity of muck to be handled
(ii) Nature of hoisting system
(iii) Nature of equipment used in tunnelling
(iv) Number of labourers needed for tunnelling
(v) Space required to carry pipes and wires
(vi) Eventual use of the shaft.

The deep water waves are those which occur in water having a depth greater than one half of the wave length (d > L/2), at which depth the bottom does not have any significant influence on the motion of water particles.
For shallow water waves (d < L/2), they influence the bottom such that particles moves in orbital motion.
An unbroken wave is wave of oscillation, and even after breaking in deep water it will usually reform into an oscillatory wave of reduced height. When it reaches to shallow water, it becomes a wave of translation.