GB2247476A - Tunnelling machine - Google Patents

Abstract

A tunnelling machine, including front and rear sections (10,12) and a cutter head, the front and rear sections being relatively moveable by rams (14). Drills (34) mounted on a platform (32) connected to the rear section (12) can drill radial holes for the subsequent provision of draw bolts at least in the upper part of the cut tunnel. <IMAGE>

Description

A TUNNELLING MACHINE The present invention relates to tunnelling machines and in particular for tunnelling machines which may be used for forming coal mine roadways.

When a coal mine roadway is constructed, the act of tunnelling the roadway relieves the compressive stresses in the soil at the location of the roadway tunnel itself and this is generally unsatisfactory and can cause the possibility of a fall of the tunnelling. It has been proposed on the one hand to provide ring supports for the tunnel and also to provide a further form of strengthening which involves the drilling of holes at a short distance from the cut face and introducing into these drilled holes, draw bolts. These fall into two types. In one type the bolt has associated with its far end, an expansible nut element which is thrust into the drilled hole and the bolt is then tightened up expanding the nut and the head of the bolt, engaging the inner surface of the tunnel wall to reintroduce the compressive forces which had been there prior to the tunnelling.Another form of draw bolt involves a rupturable container for a two part resin system which, upon rupture, rapidly cures the resin which then acts as the "nut" of the draw bolt.

To minimise the relaxation of compressive stresses and hence reduce the risk of resultant collapse of the tunnelling, the draw bolts require to be introduced into the upper part of the tunnel as near to the excavated face as possible.

In order to locate the bolts within the required distance from the excavated face with current excavation equipment, the excavating operation is required to stop to permit drilling the bolt holes. The stoppage of the excavation then reduces the efficiency of tunnelling.

It is now proposed, according to the present invention, to provide a tunnelling machine comprising a front section and a rear section; gripper means on said rear section for gripping the tunnel wall in order thereby to anchor the rear section against movement; thrust means for pushing said front section forward, relative to said rear section, when said rear section in anchored to the tunnel wall due to said gripper means; cutting means on said front section for cutting the tunnel face and radial drilling means attached to said rear section, said drilling means being arranged forwardly of the gripper means and rearwardly of the cutter means, for drilling one or more holes radially outwardly from the tunnel in at least the upper surface thereof.

With such a structure it is possible for the excavation and drilling of rock bolt holes to be carried out concurrently and achieve the necessary minimum distance to minimise ground stress relaxation.

The tunnelling machine can, advantageously, be a full face tunnelling machine and the drilling means can be mounted reasonably closely behind the cutting head of the tunnelling machine, for example, a little over 1 metre behind the cut face.

Advantageously, front and rear protective shields are provided on the front and rear sections to protect personnel working with the tunnelling machine. If such shields are provided, these shields include slots through which said radial drilling means pass and which will accommodate forward movement of said front shield relative to said drilling machines upon actuation of said thrust means.

In order that the present invention may be more readily understood, the following description is given, merely by way of example, reference being made to the accompanying drawings in which: Figure 1 is a schematic side elevation (in section) of one embodiment of tunnelling machine according to the present invention; Figure 2 is an end elevation of the tunnelling machine of Figure 1; Figure 3 is a section taken on the line III-III of Figure 1; and Figure 4 is a section taken on the line IV-IV of Figure 1.

Referring first to Figure 1, the tunnelling machine indicated therein comprises a front section 10 and rear section 12 with hydraulic thrust cylinders 14 allowing for axial displacement between the front and rear sections 10, 12. The rear section 12 is provided with laterally displaceable grippers 16 (see Figure 3) which can be urged apart by hydraulic gripper cylinders 18 in a conventional manner to grip the cut tunnel wall and hold the rear section in place while the thrust cylinders 14 are operated to push the front section 10 forwardly. The front section 10 is provided with conventional steering/stabilising shoes 20 to guide the tunnelling machine through the ground and to provide a stable support to the front section to avoid vibration generated in the cutting process.

At the forward part of the front section is a full face cutting head 22 which is provided (see Figure 2) with four radial arms 24 each provided with picks and/or disc cutters 26 which, if desired, can be mounted to be removed from the rear for replacement purposes. Situated behind the cutter head is a vent duct 28 for introducing air into the cutter head and an extractor duct 30 is mounted above this for removing unwanted gases, such as methane, from the vicinity of the cutter.

With the construction of the invention, secured to the rear section 12 is a six wheeled drill platform 32 running on rails (not shown) in the front section 10.

Mounted on this drill platform is a pair of radially extending rock drills 34 which are capable of being driven in rotation and being axially fed. The distribution of these drills is shown in Figure 4.

Surrounding the upper part, at least, of the front section 10 is a protective shield 36 which is provided at the location of the drills 34, with slots 38 extending axially or longitudinally of the shield 36. A rear protective shield 40 is similarly mounted on the rear section 12 and is arranged telescopically with respect to the shield 38.

In use of the above described tunnelling machine, when a pilot bore has been made, the rear section 12 is held against the pilot wall by actuation of the gripper cylinders 18 to urge the grippers 16 laterally outwardly against the wall. The cutter head drive motor 42 is then operated to rotate the cutter head 22 to bore the tunnel and during this operation the push rams 14 are operated to urge the forward section, and with it the cutter head, forwardly, that is to the left in Figure 1. Simultaneously, the rock drills 34 which are, in effect, mounted on the rear section 12, are operated to drill radial holes in the cut tunnel wall at a relatively short distance, preferably about 1 and 1/3 metres behind the cut face cut by the cutter head 22. The drills 34 are arranged to produce, for example, six holes by the operation of the drills first forwardly and then rearwardly along their axes, and then an indexing motion through two sets of 600 to produce the six holes, the indexing mechanism not being illustrated in the drawings. Because of the slots 38, the forward movement of the front section 10 and of the cutter head 22 can take place at the same time as the drilling operation is taking place and this can save a lot of time. Also during this forward movement the draw bolts can be inserted into the holes drilled by the drill 34 to secure safely the arch of the tunnel, at least temporarily.

If desired, conventional lining rings can be formed behind the tunnelling machine.

Claims (6)

1. A tunnelling machine comprising a front section and a rear section; gripper means on said rear section for gripping the tunnel wall in order thereby to anchor the rear section against movement; thrust means for pushing said front section forward, relative to said rear section, when said rear section in anchored to the tunnel wall due to said gripper means; cutting means on said front section for cutting the tunnel face and radial drilling means attached to said rear section, said drilling means being arranged forwardly of the gripper means and rearwardly of the cutter means, for drilling one or more holes radially outwardly from the tunnel in at least the upper surface thereof.

2. A tunnelling machine according to Claim 1 and further comprising front and rear protective shields extending over at least the upper parts of said front and rear sections.

3. A tunnelling machine according to Claim 2, wherein said front shield includes slots through which said radial drilling means pass and which will accommodate forward movement of said front shield relative to said drilling machines upon actuation of said thrust means.

4. A tunnelling machine according to any preceding claim wherein said drilling means comprise a rotary drill and means for axially moving said rotary drill and subsequently retracting the drill and means for rotationally indexing the drill to drill a separate hole in the tunnel roof.

5. A tunnelling machine according to any preceding claim and including means to introduce air immediately behind the cutter means and an extractor to remove unwanted gas from immediately behind the cutter means.

6. A tunnelling machine substantially as herein before described with reference to, and as illustrated in, the accompanying drawings.