Page 21 - Minutes of Proceedings of Civil Engineers Vol CXCV 1913-14 Part 1

l'rrmnulinge.l rIIE "WIIITE STAR" DOCK AT souTIIAMpTON. 61 lrll,x nre very useful in cases where it is necessary to penetrate to 1rr,rul, rlepths. No timber pile could have withstootl this treatment. ll, has been mentioned that at one time it was intended to drive lu,rrring-piles under the base of every pier, and this was done in e lr,r' erses. It was found, however, that the timber piles would not lrlrrr,tr':r,te more than about 5 or 6 feet into the sand, and that the lrnlrl driving increased the tendency of water and sand to blow lrr rr,l, weak spots, These piles were therefore abandoned. lrnmediately behind the trenches were situated two disused lhlrrc-story buildings. They were built of brick, standing on t'r'irrforced-concrete piles about 35 feet long. The excavation of the rr'rv tr""tr"h.. undermined these piles (especially where the blows ,u','rrrled), considerable settloment took place, and the buildings n'(tr'o badly cracked. Eventually they were pulled down in order to lrrrill the reinforced-concrete platform behind the new wall. At the south end of this wall and immediately behind it was a lrrlgo engine-house, belonging to the International Cold Storage (lrrrrpany, which was in constant use, The building was of rein- fortod concrete, 34 feet high, and built on reinforced-concrete piles. ll, rvrs of the utmost importance that this structure should not bo rlistrrrbed. Accordingly, the greatest care was taken to prevent xll,tlement of the ground atthis point. With a view to ensure this, rr lrngth of 56 feet of trench was taken only to a depth of 10 feet lx'low the 3O-foot dredging-level, and within it a continuous wall rvrrs built, the pier-and-arch construction being thus abandoned at l,his point. The style of "timbering" was similar to that of pier No. $, 1,bs trench being surrounded on all four sides with long steel xlroot-piling, extending from 20 feet to 60 feet, below quayJevel. A xlight blowoccurred from a torn pile on the front side of the trench rlhen within about 10 feet of the foundation-level. ln order to lrlrrvent the entrance of any sand, pumping was at once discontinued, rrrrtl the water was allowed to rise in the trench to about low-water lrrysl, The remainder of the excavation and timbering was carried ,rrb by divers, and the concrete was deposited under water until rllcdging-level was reached. The trench was then pumped out and l,ho rest of the wall v/as built in the dry. All piles were left in, oxcept in front of the wall, where they would have fouled the frrirway. The result was very successful: only inch of settlement $ rvts observed in the building at the back of the wall, and no serious rlrr.rn:r,ge was done to it. Ilcmarks on Pier-and-Arch Construction,-It may be said that, rrllJrough the system of building the wall with isolated piers had the rrrlyp;rtage of preyenling any one pier from being undermined while