Page 6 - Minutes of Proceedings of Civil Engineers Vol CXCV 1913-14 Part 3 Correspondence
P. 6
((\YIIITE f'r,r'nnrlings.l THE STAR" DOCK AT SOUTIIAMPTON. L2l ljr lrvt, or 2 tons respectively, his experience at Rangoon of double- Mr.Buchonon. l,,rrvrl'(xl cranes was that they were a mistake, the number of lifts .,|',rvo i|5 crvt. and less than 5 tons being so small that the higher l'u'(ll'rvits seldom used. Perhaps, horvever, the conditions at South- 'rrrrlrl,on rvcre out of the orclinary. 'With referenco to the bottom of llr rkrckr and the advantage claimed that the mud deposited in the ,lrr,ks rv:ts of such a soft clayey nature that no damago was done to r,'qxols if by chnnce they should touch bottom, whilst concurring in llrr, stttement, ho would like to hear rvhat shipowners had to soy on t lris lxrint, as, judging from his own personal experience at various ;ur'|,s, shiporvners protested vehemently if their vessels touched the lurl,trrm, rvhatever the n:rture of the ground, I\lt'. F. G, CannoN inquired rvhether any attempt had beon lnads I\tr.cnrron. l,' lx'rl the blocks forming the faces of the walls which were built rrrrrlrrr w&ter on morL.ur. 'Ihe section (Fig. 8, Plate 2) indicated r,,r'l,icnl joggles. Were these of concrete in bags, and were they l"'uu(l sntisfnctory in preventing the concrete hearting from being rlisl,trrbed while setting? It woulil be seen from the summar)- of llrr,t:onsiderations govorning the design of the dock-walls, given in Alrlxrndix I, that the material nt the back of tho walls was not ru'rrtorlogged, thnt was to sny, the wall was not under hydrostatic lrr'('ssure nt the back, fls it was in front. IIe considered that this rurrs rr point rvhich could not be conceded in the case of severol ,lrrrry- a.nrl dock-walls with which he was acquainted. At the port ,l l)rwri, for exarnple, the tide rose and fell in the filling behind l lrr' 1vflls, and so resistrince due to water-pressure could not be Irrlitrn &s n supporting force in ollculating their sbability, Surely, Irorvcver, the force of gravity was the main consideration. This I'orr:c, compounded with the lateral pressures behind the wall, I'rrrrrght the resultant thrust on the foundations, the force of grrrvity being the weight of the wall-partly in water, of course, in I,lrrr cnsc of wnlls with waterlogged backing. At Parrl reinforced- lorrcrete beams 32 feet by 3 feet 4 inches by 3 feet 4 inches were rrricrl to form the bnse of a wall which had a tota.l height of i I fcct 6 inches. These beams were laid on foundation rubble ;,r','prred by divers, and they projected os a toe 5 feet in front of t.lrrr ordinary block-work toe of the wall. They had served very rvcll to distribute the pressure at the toe, and to act as cross ties at t,lro bnse of the wall, which wos of block work laid in sloping slices. Mr. W. Dycn Cav agreed with the Author that it would have Mr. coy. lrrxrn better to build the walls for portion B entirely of blocks, instead ,'l' :r block face and a hearting of concrete, deposited liquid in the rurrtcr. IIe had found that, both in bridge-cylinders and in sea-
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