October 16, 1914 THE COLLIERY GUARDIAN. 821 A Means of Securing Main Haulage Roads and Return Airways of a Mine Otherwise than with Timber.* By “CYMRO. About three years ago it was decided to adopt some permanent form of support for the roof and sides, other than timber, on the main roadways at the colliery where the writer is employed. Brick and stone arching had been put in extensively, but the progress was slow and the cost high. The writer, when visiting a neighbour- ing colliery, saw for the first time a portion of a main Fig. 1. diameter at the widest point, i.e., at 3 ft 4 in. above the floor. This form has been proved to be very effective in resisting both top and side pressures. The section of the girder used is 4 in. deep, flanges 1| in. wide, and the web T7S in. thick, weighing approximately 9 lb. per ft. The fishplates consist of two plates 18 in. long, f in. thick, 2J in. wide, with the holes | in. square, and 5 in. pitch. The road obtained with this type of girder is of the ■following dimensions :— Height under girder.......... 7 ft. 10 in. Width (3 ft. 4 in. above floor)... 9 ft. Width in bottom ............. 7 ft. 10 in. Area.......................... 59'8 sq. ft. Approximate weight ............ 188 lb. per girder. This section is used on main haulage roads. At present there are four sections in use at these col- lieries, the other three varying only in dimensions from fig. 1. These are shown in figs. 3 and 4. Fig. 2 is the largest section put up, and is used on double partings and in stables. The main dimensions are :—■ Height under girder............ 10 ft. 4 in. Width (3 ft. 10 in. above floor).. 13 ft. Width in bottom ............. 12 ft. Approximate weight............ 2481b. per girder. Fig. 3 is used in return airways which are not used as haulage roads. The dimensions are :— Height under girder.......... 6 ft. 8 in. Width (3 ft. 4 in. above floor)... 7 ft. Width in bottom ............. 6 ft. Area......................... 39'3 sq. ft. Approximate weight............ 160 lb. per girder. Fig. 4, used in small airways and walking ways, and is of the following sizes :— Height under girder......... 5 ft. 10 in. Width (3ft. 3 in. from floor) ... 5 ft. 7 in. Width in bottom ............ 5 ft. Approximate weight........... 140 lb. per girder. tance apart the girders are to be set. There are three dogs used, one at each side at foot of girders, and one on the crown. These dogs hold the girders at whatever angle they are required to be set until the sides are packed with stones and rubbish—where there is space on the sides—or until they are secured with wedges or laggings. The dogs are then taken out, and are ready to be used to hold the next pair in position. It is always advisable to have at least space for laggings, between the girder and the sides of the roads, the timber thus acting as a cushion. This we have proved by experience. After the packing is carried up as high as possible to the “ quarters ” of the girders, the quarters and crown are cased with one course of laggings put close together, the space between this timber and the ground being closely packed with rubbish. The thickness of packing on top of the girders varies in accordance with the height the roof has fallen. Under conditions where the ground breaks up very high on the timber set in the roadways, and which timber is to be replaced by girders, the method adopted is to “ cut out ” for a length of say 8 ft. or 9 ft., clear the “ fall ” away, erect temporary timber for safety, and then set a number of girders 18 in. apart, secured at the sides and crown as described before, after which the space between the crown of the girders and the roof is filled up by ground taken from over the adjoining timber on the roadway. By this method the girders are properly packed, and at the same time a space is prepared for the next length of girders. The writer has had hundreds of yards of main haulage roads secured by this method. The sides between the girders are filled in with brick- work 4| in. thick, which, at first, was carried up to a height of 4 ft. from the rail, but, later on, the sides were bricked up to a height of about 6^ ft. where 9 ft. girders are used, and higher still where 13 ft. girders are used on double partings. A special brick is used for this purpose, which fits the girder without chipping. A plan of this brick is shown in fig. 6. As can be seen, the small end fits in between the flanges, which allows the brick to project about | in. outside the girder. The brickwork, therefore, protects the girders from being knocked out or damaged by trams in cases of “ wild runs,” etc., on high-speed haulage roads. In eases of shackles or drawbars breaking on roads rising 1 in 6, the utility of the brickwork between the girders has proved very satisfactory, as on many occasions when 12-0 Fishplate 18x^6 Holes 8 - IO' hl 0) 6 Fig. 2a. Fig. 5. Fig. 3. 5 Pdfch — b Section haulage road secured with steel arching girders. Experi- ments were made with the girders, which are made of one section steel joists rolled in the form of a horseshoe. In the section first adopted (fig. 1), this girder consists of a curved steel joist in two halves, joined together in the crown with a pair of fishplates and four bolts, two bolts being in each half. The upper part of the girder is semi-circular in shape, being curved to a radius cf 4 ft. 8 in., but the two legs, instead of being perpen- dicular to the floor, are curved inwards, so that the bottom of the girder is 1'ft. 2 in. narrower than the * From the Journal of the Monmouthshire Colliery Officials’ Association. The writer was awarded a prize of £5 given by the association. %■ Heles Fop% Bolls Fig. 4. "'45 >'5 1^ Method of Erection. A large quantity of old wagon cill planks and head- stocks (oak) have been used under the feet of the girders, also ordinary colliery sleepers and flats. The ground being taken out for as long a length as the nature of the strata allows, a longitudinal trench is cut on each side of the roadways and parallel to it. The oak planks, sleepers, or flats, whichever is to be used, are put in these cuttings so that the upper surface of such timber is slightly below the level of the rail. The girders are then put together -with their feet on the timber. They are held in position by “ iron dogs,” fig. 5, which grip over the flanges of the two girders, the centres of these “ dogs ” corresponding to the dis- breakages have occurred the girders have held without moving. Under similar conditions “ double timber ” would have been knocked out, heavy falls brought down, and delay to the traffic of the district. Another great advantage experienced by bricking between the girders is that a smooth surface is obtain- able on which coal dust cannot easily accumulate, and can be cleaned with very much less labour than when haulage roads are secured by timber. Again, it enables practically the whole circumference of the roadway to be -watered, and this, without the watering having any evil effect on the roof and sides of the strata, such as causing it to “ work,” as is so often the case when roadways secured with timber are