1301 THE COLLIERY GUARDIAN. June 12, 1914. lining of shafts, cross cuts, pit eyes, pump and engine chambers, dams, etc. In the lining of shafts, an important feature of ferro- concrete construction is its power of resisting heavy earth pressures. An example of the diverse effects of such movements may be cited in the case of the Rheinelbe No. 6 pit of Gelsenkirchener Bergwerks A.G., the lining of which was carried out by Messrs. Schluter. In this case 186 screws of 1T% in. diameter, which were fixed in the horizontal tubbing segments, were broken right off in deepening the shaft below exhausted seams in consequence of the torsional pressure of the strata (see figs. 1 and 2), so that separate tubbing rings were dis- placed to the extent of as much as 1| in., whereas the ferro-concrete built into the tubbing, owing to the fact principally that it was parallel to the vertical axis of the shaft, had withstood these movements. Owing to its greater power of resistance ferro- concrete takes up less space in comparison to brick- work, thus not only effecting a saving in material, but also considerably reducing the quantity of material to be excavated. In the case of a certain shaft having a clear diameter of 19 ft. 8| in., lined by the firm, a brick walling 2 ft. 6J in. in thickness in the shaft required a diameter of 19 ft. 81 in. + 2 (2 ft. 61 in.) = 24 ft. 91 in., whereas a ferro-concrete lining 11 in. thick only required a diameter of 19 ft. 8| in. + 2 (11 in.) = 21 ft. 61 in., so that for every one rising foot of the shaft 120 cu. ft. less rock had to be blasted and removed, leading to a considerable economy. As ferro-concrete only becomes solid after some lapse of time, and as moreover pressures are often met with in places during the course of erection, it is of the utmost importance that the frame during the operation of lining should be strongly arranged so as to withstand every unexpected pressure. One of the iron ring frames employed by Messrs. Schluter for this purpose is shown in fig. 3. Figs. 4 to 8 illustrate some of the work done by the firm, and show the extraordinary adaptability of this material in overcoming the natural difficulties that frequently present themselves at junctions and other places below, ground. Fig. 9 shows the means adopted by the use of the cement-injecting process of dealing with springs encoun- tered in the shaft during the operation of lining. A speciality of the firm is the lining with iron tubbing, strengthened on one or two sides by ferro-concrete, as shown in fig. 10. In addition, Messrs. Schluter have carried out numerous surface installations in the Ruhr coalfield, some of which are shown in figs. 11 to 14. Fig. 9.—Showing Use of Cement-injecting Process. Fig. 10.—Reinforced Tubbing. ■p t-l -f- flMHM ■■■ '<■ i. :- '■'■ ■ ’'''’A' jftft w I A'AAfl • ' ; ■ . / . ■ t *A ft ■ '/' ' A ' ■'A ffc »■': A: Aft ■'