Patent GB-190811253-A (GB)
Title: Improvements in and relating to the Construction of Caissons.
Inventor: EDWARDS OLIVER CROMWELL
Filed: 1908-05-23
Granted: 1909-05-20
Abstract: 11,253. Edwards, O. C. May 23. Caissons and coffer-dams.-Relates to the construction of caissons, more particularly those made of concrete, the chief object being to produce great strength while using a mimimum amount of material. The thin walls of the working-chamber are formed integral with stiffening - trusses, and the roof is also provided with trusses. Fig. 1 shows a plan, and Figs. 3, and 7 longitudinal sections of one form of caisson, and Figs. 19, 25, 44, and 50 are longitudinal sections of modifications, but further modifications are described. The work ing-chamber is preferably crossed by longitudina trusses 10 and transverse trusses 11, and above the roof are similarly or dissimilarly disposed trusses 22, 23, which may be tied together by vertical tierods as shown in Fig. 7. The thin walls 2 and their extensions 1<1>, 2<1>, which are sometimes omitted, are formed integral with trusses 5, 20, 21, formed of upper and lower chords connected by diagonal braces and vertical studs, but other forms may be employed. The roof also is made thin and is stiffened by a longitudinal beam 12 and transverse beams 13, which together produce pockets in the roof. Fig. 19 shows beams 40 on the underside of the roof supported at their ends by knee-braces 41. Continuous knee-braces may be employed in connexion with all the roof beams as shown at 18<1> in Fig. 1, at 24 in Fig. 12, which shows a wall panel formed by the wall braces &c., and at 62 in Fig. 25 ; or disconnected knee-braces 25, Fig. 12, may be used. The extensions 1<1>, 2<1> form a kind of coffer-dam, and may be of any height but they are preferably made low, a wooden coffer-dam, part of which is shown in Fig. 25, being mounted thereon. The roof itself may sometimes form the upper and lower chords respectively of the trusses which cross the working-chamber and coffer-dam. The various parts of the caisson are tied together by metal rods, and metal reinforcements may be inserted in the chords, braces, studs, &c. The tribedral angles produced by the knee-braces, walls, and roofs, or by the walls and roofs, may be filled in with trihedral fillings 26, Fig. 12. The corners of the caisson are protected by angle-plates, and the cutting-edges are strengthened by a metal reinforcement consisting of an horizontal truss 29, Fig. 10, and a vertical truss 30 made up respectively of chords 31, and a bracing- web 32 of diagonal bars, and of chords 33, 34 and web 35. Reinforcing-bars 37 are secured to the trusses 29, 30. In the form shown in section in Fig. 25, the coffer-dam is strengthened by side and end trusses connected to the roof by vertical studs 49 formed integral with knee-braces 46, and the longitudinal and transverse trusses 50, 51, 59, 60, which cross the coffer-dam, consist simply of top and bottom chords connected by vertical studs, provided with knee-braces. The coffer-dam proper is connected by means of walls 53, 54. Fig. 50 shows transverse braces 96 formed integral with the side walls and connected to the roof 95 by vertical studs 97, and similar longitudinal braces may be employed. Knee-braces 98 and trihedral fillings 99 are preferably used at intervals where the roof joins the walls, and tribedral fillings are used in the angles formed by the roof, ends, and sides. Fig. 51 shows in detail one form of connexion between the air-shaft and the roof 95. The shaft 117 rests upon an embedded annular angle-iron 118, and is bolted thereto by means of an angle-iron 119 and embedded bolts 120. Fig. 56 illustrates in transverse section the employment of thin webs 130 instead of bracings for the strengthening-trusses. Sometimes knee-braces, Fig. 61, extend continuously of the contacting-edges of the roof and walls, and in this form the structure is further strengthened by beams 134, 135, 137, 138 connected to the roof by vertical struts at their points of intersection ; in a modification these trusses are made solid. The details described may be employed in varying combinations, and several tiers of trusses may be built where desirable. In order to build a subaqueous tunnel, a number of caissons are sunk end to end, the working-chamber 140, Fig. 58, is filled with concrete, and the tunnel walls 141 are cast upon the caisson before the coffer-dam walls are removed. Figs. 40 and 42 show in plan and horizontal section, respectively, a simple form of construction in which the roof is built integral with strengthening-beams 77 interrupted by a thickened portion of the roof 78 arranged to support the shaft. The walls are strengthened by trusses consisting of lower chords 81 and vertical studs 82. Fig. 44 shows a somewhat similar construction with knee-braces 84, 85 for each of the vertical studs.