GB2192920A - Method of excavation and apparatus therefor - Google Patents

Abstract

A tunnel is constructed by progressively cutting away a predetermined depth of rock from a face using rotary diamond saws. Slots are cut into the face (12) at an acute angle to the face such that first slots intersect second slots to detach blocks from the face. In one embodiment, the cutter (29) is mounted on a slide which can traverse an elongate guide 26. The guide is carried on an arm (24) which can swivei about its own longitudinal axis. A series of angularly spaced slots are cut into the face through 360 DEG with alternate slots being cut at opposite acute angles to the face so that they intersect. A cylindrical tunnel is produced. <IMAGE>

Description

SPECIFICATION Method of excavation and apparatus therefor This invention relates to a method of excavation and apparatus therefor.

The invention is especially concerned with construction of tunnels, but is useful whenever it is required to excavate a recess.

Tunnels have usually been constructed by drilling holes, generally parallel to the intended tunnel direction, in a face to be excavated, inserting explosives in the holes and blasting away a short length of the intended tunnel.

The resultant rubble is then removed by mechanical shovels, an arch or other support is mounted in the excavated portion and the process is repeated.

In coal mines in particular, it has been known to mill the recesses known as stable holes, which are formed at each end of a coal face. Such techniques are much cheaper and quicker than blasting techniques, but are usable only with soft mineral, such as coal itself.

Where hard minerals are met, the blasting technique is normally used in a coal mine.

Another alternative is to use a large drill to drill out the tunnel. The machinery to do this is extremely expensive both to manufacture and to use and expensive techniques have to be utilised to flush out the drilled material and to dispose of the material.

The present invention provides a method of excavation (and apparatus therefor) which has many of the advantages of the drilling technique, out which is relatively cheap both in respect of the cost of the apparatus used and the cost of operation.

In accordance with this invention, there is provided a method of excavating a recess in a given direction in a face, comprising cutting a series of slots into the face, the slots being cut at an acute angle to said given direction, some of the slots iptersecting with others of the slots, and said some slots being inclined to said other slots, whereby blocks of material are separated from the face.

Reference is now made to the accompanying drawings, wherein: Figures la to ic are a side elevation, plan and end elevation respectively illustrating a first embodiment of apparatus according to the invention; Figure 2 shows the cutting pattern effected by the apparatus of Figures la to 1c; Figure 3 is an end elevation of a second embodiment of apparatus according to the invention; Figure 4 is a side elevation of the apparatus of Figure 3; Figure 5 is a plan view of the apparatus of Figures 3 and 4; and Figure 6 illustrates the cutting operation of one cutting head of the apparatus of Figures 3 to 5.

Referring to Figures 1a to Ic, there is illustrated apparatus for forming a cylindrical tunnel 11 by cutting into a face 12. The apparatus comprises a self-advancable body 21 mounted on caterpillar tracks 22 for advancing the apparatus in the tunnelling direction, generally perpendicular to the face 12. The apparatus cuts blocks of material from the face in a manner to be described and includes conveyors 23, 25, extending in the tunnelling direction. The conveyors are arranged to collect the blocks which fall from the face and is continuously operable for removing the blocks as they fall.

An arm 24 is swivellably mounted on the body 20 about its own axis and this arm extends from the body in a forward direction so as to lie substantially along the axis of the cylindrical tunnel 11. At its end remote from the body, the arm carries a transverse guide 26 which extends along a diameter of the tunnel with a small clearance at each end. A slide 27 is mounted in the guide for movement therealong.

The slide 27 rotatably mounts a pair of rotary cutters 28, 29, spaced along the guide 26. The slide includes angle-setting means (not shown) which set the cutters at an acute angle to the face 12 and to the tunnel axis.

This angle may be about 45 . Adjustment of the angle is not required.

The cutters are mounted in a secondary guide (not shown) on the main guide 26. This secondary guide permits movement of the two cutters 28, 29, relative to the main guide 26, intb the face at said acute angle at the initiation of a cutting operation. This movement is indicated by arrow 'A' in Figure 1a.

Drive means is provided for swivelling the arm 24, driving the slide 27 along the guide 26, driving the cutters in the secondary guide and for rotating the cutters. These drive means may be electrical and/or hydraulic with electrical control and involves only normal workshop, engineering skills to put into practice.

The cutters are preferably discs with diamond saw teeth, but could be cutters of other forms.

The apparatus is used to cut a series of slots into the face 12, such that the slots intersect to cut blocks from the face, which are carried away on the conveyors. Each slot extends substantially the full diameter of the tunnel and the slots are angularly spaced at the face 12.

In order to cut one slot, the cutters 28, 29 are rotated at high speed and the cutters are advanced in the secondary guide so as to cut into the face 12 a oredetermined distance.

The slide 27 is then moved along the main guide 26, so that the cutters cut a slot along the diameter at which the guide 26 lies. The cutters are then withdrawn and the arm 24 is swivelled by a few degrees, so that the slide lies on a different diameter. The cutters are then advanced again to cut into the face and the slide traverses the main guide 26 in reverse direction to cut a second diametral slot.

This cycle is repeated until the arm has been angularly moved through 360 about axis 10 (Figure 1b).

After the arm has been swivelled through 180 , the slots are cut in an angular direction towards those already cut, so that each slot intersects with an existing slot. This is achieved without adjustment of the cutters, since the cutting direction reverses at 180 of rotation. This intersection of slots means that pieces of material are separated from the face and fall onto the conveyors. Most of the material can be removed in this way, leaving only small pieces at the periphery, which are readily removable by hammer blows.

The whole apparatus can then be advanced for a repeat cycle to extend the tunnel.

The cutting pattern effected by the method described above is illustrated in Figure 2.

In order to produce a wider tunnel, apparatus as disclosed in Figures 3 to 6 is used.

This apparatus, again has a self-advancable body 121 mounted on caterpillar tracks 122 for advancing the apparatus in the tunnelling direction B. A central conveyor 123 is provided for removing debris.

A pair of beams 124, 125 are mounted on the body 121. The beams extend in directions opposite to each other in alignment and perpendicular to the direction of tunnelling B.

Three arms, 127, 128, 129 are swivellably mounted on the body about aligned axes. A first arm 127 is pivoted on one of the beams 124, a second arm 128 is pivoted on the other beam 125 and the third arm is pivoted centrally of the beams, about axes 127a, 128a and 129a respectively. The axes all extend in the tunnelling direction B.

Each arm carries a guide member 135, slidable on the arm a!ong a path acutely angled to the tunnelling direction B and to the face 12. Each guide member rotatably mounts a pair of rotary cutters 130, 131 which lie parallel to the path of the slide. The guide member includes angle setting means (not shown) which set the cutters at said acute angle to the face 12 and to the tunnelling direction B.

The guide member 135 is mounted on a slide (not shown) for movement along the respective arm 129.

Drive means is provided for swivelling the arms 127, 128, 129, for driving the slides along the respective arms, for driving the guide members and for rotating the cutters.

Each pair of cutters is operated in a similar manner to that of the embodiment previously described. The three pairs of cutters operate simultaneously to cut angled slots into the face 12. The cutters are then moved by their slides 135 along the arms 127, 128, 129 to cut an elongate slot. The cutters are then retracted and all three arms 127, 128, 129 are swivelled through a predetermined angle for a repeat cutting operation. This procedure is repeated through 360 .

The tracks of the three cutters overlap and they are interdigitated so that there is no interference during the cutting cycle. After a complete cutting cycle, small pieces remain attached at the periphery, as in the previous embodiment, which can be removed by hammer blows. In order to provide a flat roof and floor, ridges 140 to 143 remaining between the regions cut by the three pairs of cutters can also be removed by hammer blows.

Auxiliary conveying means 150, 151 are provided alongside corresponding beams 125, 126 for collecting material removed by the cutters on the first 127 and second 128 arms. This material is conveyed to the central conveyor 123 for removal from the site.

The methods of cutting tunnels described above are substantially cheaper to carry out than existing methods and rock of all types can be cut by the apparatus described. It is only necessary to vary the rotary cutting speed according to the hardness of the rock being cut.

The methods described above enable the tunnel supports to be placed close to the face after each section has been cut. This is not possible with blasting techniques and there is greater safety in carrying out the method according to the invention.

Claims (7)

1. A method of excavating a recess in a given direction in a face comprising cutting a series of slots into the face, the slots being cut at an acute angle to said given direction, some of the slots intersecting with others of the slots, whereby blocks of material are separated from the face, characterised by cutting each slot across an axis extending in said given direction and cutting said slots at angular spacings about said axis through substantially a complete circle.

2. A method according to Claim 1, in which a plurality of series of slots are cut through substantially respective circles which circles are side-by-side and overlap.

3. Apparatus for excavating a recess in a given direction in a frame according to the method of Claim 1, comprising cutting means a support having first guide means for guiding the cutting means to cut into the face, second guide means for traversing the face to cut a slot in the face, means for locating the cutting means at an acute angle to said given direction and to said face, and adjustment means oermitting rotational adjustment of the support about an axis (10) for cutting slots which are angularly spaced around the axis.

4. An assembly comprising a plurality of apparatus according to Claim 3, wherein the oaths of the cutters in adjacent apparatus overlap during rotational adjustment of the supports, the adjustments being controlled so that the respective cutters interdigitate.

5.-An apparatus according to Claim 1, or assembly according to Claim 4, including conveying means for removing blocks of material separated from the face.

6. An apparatus according to Claim 3, substantially as herein described with reference to the accompanying drawings.

7. A method according to Claim 1, substantially as herein described.