8o NOTES ON DOCKS AND DOCK CONSTRUCTION. 



with regard to the foundations for the entrance lock at the 

 Albert Docks, Hull, carried out under the direction of Sir 

 J. Hawkshaw, P.P.M.I.C.E., are of special interest, illustrating as 

 they do the difficulties encountered, and the expedients adopted 

 in dealing with clay and sand under exceptional conditions. 



The whole length of the entrance is G56 feet, and of the lock 

 320 feet, between the sills, by a width of 80 feet. The depth 

 of water over the sills is 27 feet 3 inches at high water of 

 ordinary spring tides, and at low water 22 feet 9 inches. 



The strata consisted of first a deposit of silt or warp resting 

 on a bed of peat, beneath the peat came two beds of boulder 

 clay divided by a deposit of sand. The clay in both beds 

 was compact and generally without pot-holes of sand and 

 gravel. The upper bed was full of rounded and angular 

 fragments of various rocks, whilst the lower bed was free 

 from stones. The lower clay was separated from the chalk by 

 a bed of sand some 16 feet thick (Fig. 57). 



Guided by the strata excavated for the return wall near the 

 railway creek and by borings, it seemed probable that a bed 



H.W.O.S.T. 



^;fji^fm^^mK-mi^^ 



SECTION ON LINE K L, FIG 58. 



VERTICAL SCALE 



^O _ KJO _ 150 _ 200 FE~T 



HORIZONTAL SCALE 

 IOO__BO_J> _ j _ 5 _ ? 4 p e CHAINS 



FIG. 57. 



of sand about 8 feet thick would be found between the upper 

 and lower beds of clay at a depth varying from 50 to 54 feet 

 below coping. It was therefore decided that the same plan 

 should be adopted for the foundations of the lock as had 

 previously been successfully carried out for the dock walls, i.e. 

 to remove the upper bed of clay and the sand below it, an- 1 



