DE2209821A1 - Process for consolidating fragile rock layers - Google Patents

Description

PATENT LAWYERS DR. O. DITTMANN K. L. SCHIFF DH. A. ν. FONBR DIPL. ING. P. STBEHL MUNICH SO MARIAHILFPLATZ 2 * 8 '

DA-4727

Description of the patent application

of the company

EXPLOSIVES AND CHEMICAL PRODUCTS LIMITED 31-35 Wilson Street, London EC2M 2UA England

concerning

Method of solidification! of fragile rock strata Priority: March 1, 1971, England, No. 5729/71

The invention relates to the consolidation of rock layers, The invention relates to a method for consolidating fragile rock layers, in particular, however not exclusively of subterranean rock layers with a brittle or crumbly structure, such layers can be found in mining technology and in road construction in underground roads and tunnels.

It is already known to connect the roof layers in underground mine systems with one another by means of tensioning roof bolts, the holes drilled in it either mechanically or

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are anchored using synthetic plastic compounds. This way the need of use becomes of wooden bracing to support the roofs of the tunnels and roads in underground mines avoided. However, the use of such roof bolts is not always satisfactory for fragile rocks, as the walls the boreholes cannot be stable enough to allow adequate tensioning of the roof bolts. To the This disadvantage was overcome in the British patent 1 166 8i6 already proposed a non-tensioned, smooth consolidating rod with an asymmetrical Head is provided to be used in a borehole with a clearance of 1.5 mm in conjunction with a cartridge, which in separate compartments a polyester resin together with a filler and an accelerator and a Contains hardener for the resin. The reinforcement rod is formed from a Kolir, which is covered with a reinforcement material, like cement, is filled and that on its outward facing End is designed so that it seals the end of the borehole. Such consolidation rods need to be inserted a mechanical pressure in the region of 900 kg. Therefore, they can only be made using relative complicated machines are installed, which are not available in most underground mines. Farther such smooth consolidation rods can be removed from the boreholes at a load close to the Yield strength of the material used for the pipe.

The invention is therefore based on the object of a method and devices for the consolidation of underground To provide rock strata, which makes the installation of a reinforcement part in a fragile Rock drilled borehole using relative

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simple, hand-held drills are possible and the easy removal of the reinforcement piece from the borehole is prevented.

It has now been found that this object by the use of a tubular reinforcement member with enlarged End parts in a borehole with a diameter such that between the wall of the borehole and the body or Body part of the reinforcement part an annular space of at least 2 mm, preferably 3 to 5 mm, dissolved can be, wherein the reinforcement member in the borehole preferably over substantially its entire length under Using a mass attached to a polyester base.

Ira trap that there is a widened or enlarged end part the hollow reinforcement part from the mouth of the borehole extends forward, a base plate is advantageously attached to the widened end part, that it is in contact with the rock that is on the dog dea borehole. For this purpose, the widened End part may be provided with means for attaching a base plate to the end part of the reinforcement part.

An unforeseen benefit of using a tubular Reinforcement part according to the present invention consists in the fact that when a tensile stress is exerted on the tubular part up to the yield point of the material, from which the tubular part is made, no significant Movement takes place. The tubular part is usually made of a metal or alloy such as steel. Above the yield point or the breaking point the material stretches uniformly over its entire length between the two widened end parts downwards, what

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is in contrast to a solid rock bolt which is mechanically or using a Resin is anchored and, if it is placed under tension beyond the yield point, adheres to one Constricted point downwards and ultimately at this point with a relatively small expansion of the bolt breaks. This surprising effect is of significant value for the use according to the invention for aiding of mine roofs, as the additional stretching of the reinforcement part forms a valuable safety factor, which is missing when the conventional rock bolts are used. In a typical bolted road, where fully resin-bonded, curled steel rock studs about 18.3 cm in length could be used a roof movement of only about 5.08 cm indicates the impending breakage of the steel bolts. On the other hand, when using the steel, tubular reinforcement parts according to the invention a movement in the order of 25, ^ to 30.5 ^ m be endured before the reinforcement members are critically stressed. Thus is at an embodiment of the invention, the tubular reinforcement part provided with a longitudinally extending fixed indicator rod, which in use on the inside End part of the part is fixed, and wherein the rod protrudes from the other end part of the part in such a way that it can display all extents while using the part.

The reinforcement part according to the invention, which in general is formed from a metal or an alloy, preferably steel, is advantageously in connection with a compound on polyester resin base used, which is preferably in a multi-component single compartment cartridge, as described in British Patent 1,127,913 (corresponding to copending application No. i * 96O6 / 7O), is packed. If desired, however, the tubular

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Reinforcement part with other binding materials, e.g. Portland cement, Plaster of paris or a resin-reinforced hydraulic mixture that is injected into the borehole in a premixed form will be installed. When the reinforcement member together with a binding material packed in a cartridge is used, the part must be rotated during insertion into the borehole to avoid destruction of the cartridge housing and adequate mixing of the reactive components, in view of the However, the annular space used according to the invention can do this rotation with hand-held drills be effected with relatively low mechanically exerted pressures of 20 to 50 kg.

Various embodiments are shown in the accompanying drawings of the tubular reinforcement parts according to the invention shown.

In the embodiment according to FIG. 1, there is a reinforcement part from a piece of steel tubing notched at each end and then stretched by inserting it into a conical part of steel has been driven. This practice is advantageous in that it is easier to use the expansion of the outer end of the tube in this way at the same time as the fixation of a base plate can perform.

In the embodiment according to FIG. 2, there is a reinforcement part from a steel tube, the ends of which have been expanded by hot working the metal on a suitable deforming tool.

In the embodiment of FIG. 3, one end of the steel pipe is expanded in such a manner by hot working been that a device for attaching a

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consists of a threaded pin to which a base plate can be attached when in use. The other The end of the tube can be expanded in the manner shown in FIG.

In the embodiment according to FIG. Zf, the appropriate Expansion of the end portions of the pipe is achieved by threading the pipe over a short length at each end has been rolled out. In this way it is possible to increase the diameter of the ends of the pipe by up to 2 mm. This procedure has proven to be very suitable for a firm anchorage at the ends of the reinforcement part to achieve. One end of the tube can go through a simple Stopper made of metal, wood or plastic material closed which only needs to withstand the insertion pressure of the pipe by a resin cartridge.

FIG. 5 shows a further embodiment of the invention according to reinforcement part, in which at one end of the tube a conical part is expanded and with a coarse Thread is provided. When using this reinforcement part, Pin becomes a short piece of thick-walled plastic pipe inserted into the borehole in front of the resin cartridge (s), whereupon the part rotates onto the normal version is used. After mixing the contents of the cartridge (s) engages the threaded end of the bolt into the plastic socket, thereby this is expanded against the wall of the borehole and an immediate support is created for the part, before the resin has started to harden. Such a support bushing is used to support the reinforcement part in the borehole, and it allows the immediate removal of the drill, according to those described below Measures can be attached to a base plate.

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The simplest way of attaching a base plate to the reinforcement part is to use the Embodiment of FIG. 1, which at its inner end is expanded prior to insertion in the borehole · A tight fitting is made over the protruding end of the pipe Base plate with a central opening is placed and a hydraulic ram is inserted into the open end of the pipe tapered conical wedge hammered or depressed to expand the end adjacent the opening in the plate. This procedure for fastening the base plate is shown in FIG. 6.

An alternatively feasible method for attaching a base plate provides for the use of a tubular reinforcement part with a steel grub screw at the outer end, as shown in Fig. 3. In practice this reinforcement part is used in the usual way and then a standard roof bolt base plate is applied to the protruding pin and, as in 7, tensed by conventional means.

In Fig. O a reinforcement part is shown that the one is similar to Fig. 1 but has an axially extending one Has rod attached by screw threading at one end to a coiled socket in the conical portion and which extends at the other end through an axial hole in the ionic coil at the end so that an indication of the expansion of the tubular part in use is given «

Around the annular volume between a rock bolt or dowel and the borehole drilled to receive it as small as to make possible and thereby to make the amount of resin composition used as small as possible, the tendency is in the

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Mining industry to drill holes of a diameter that are only slightly larger with respect to the reinforcement element. For dowels of relatively large diameter, this approximation is quite satisfactory. It is now customary to use wooden dowels with a diameter of Z> 0 mm or J $ 6 mm in drill holes with a diameter of 56 mm or 4 mm. In the case of steel dowels with a relatively small diameter, ie between 16 and 25 mm, which have adequate internal strength for the consolidation of layers, however, it has proven difficult to drill boreholes with a sufficiently small diameter. In certain hard strata / where intricate drills of adequate power are available, 16mm rods have been successfully inserted into 22mm holes. In softer dry shale layers, successes were achieved with 20 mm rods that were inserted into 28 mm drill holes. However, the formations to be bolted contain water-bearing layers which wet the drilling dust and easily clog the small diameter boreholes. In practice, therefore, the difficulties of drilling boreholes 28 mm in diameter and less under normal conditions in the British coal industry have greatly delayed the use of reinforcement dowels fully bonded with plastic for permanent support.

The advantage of being able to drill relatively large boreholes, that is to say with a diameter of 36 to kj> mm, can be tubular according to the invention together with large steel reinforcing dowels. shaped nature can be used. In addition to the ease of drilling the holes, another advantage of the invention is that the invention allows a relatively large area for load distribution around the individual reinforcement members. In the case of the frizzy artifacts, which are completely bound with resin,

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In the case of rock bolts, if 28 mm holes are used, there is a real risk that in rocks with low compressive strength, which are exposed to high pressures across the direction of the bolt, the rock will be pressed against the bolt. When using a tubular reinforcement part with a larger diameter in a borehole with a diameter of 10 mm, a considerably better load-bearing capacity is achieved under these conditions, since at a given base pressure the compressive load exerted against the rock in connection with the bound part is only about & 0% of that that occurs in a 28 min rock bolt.

Although it is naturally possible to use a reinforcement bolt with a relatively small diameter in a large hole install, the cost of such a system is high because a large amount of binding cement must be used. the Installation costs of the tubular reinforcement members according to the invention are comparable to those that bex solid bolts arise in drill holes with a small diameter.

The tubular reinforcement members according to the invention are primarily for use for the complete or complementary Suitable for support or carrying in mine roads and the like. In this use, tubular Pieces of appropriate length, up to 1 m, are inserted into the layers surrounding the rock opening. A The immediate surface rock can be peeled off by attaching suitable base plates to the exposed Ends of the reinforcement members are depressed to a minimum value. When used like this, it is important to watch the movement of the supported shift beds so that an appropriate warning is given for an impending one Break of the supported structure can be given. to

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for this purpose, "various devices have been used so far been to the bed partition in the roof of a mine road to eat. Such devices only measure the movement of the ground and do not show any training of tensions within the individual reinforcement parts. The tubular reinforcement part according to the invention has the advantage that the actual bolt tensions can be measured by an internally calibrated rod, which is located inside the tubular bolt itself. That was described in more detail above in connection with FIG. In the event that there is heavy stress in the body of the part forms, which causes an expansion of the reinforcement part, one observes that the exposed free End of the rod retracts in the open end of the tubular part »Such a situation indicates that the tubular Part already in excess of the stretching load carries loads, and gives a valuable warning for severe movement within the supported roof structure.

The embodiment according to FIG. 7, in which a base plate attached to the tubular member by means of a capture pin is therefore particular Value because they have a high degree of flexibility in using the system allowed. For example, it is not always desirable or necessary to extend the tubular member over its entire length to tie, so that in a borehole with 183 cm an adequate Behavior can be achieved if you only the upper 121 cm of the tubular part into the borehole. binds. When using this method of fixing the plate, it is possible to determine the lengths of the tubular part and the fixed catch pin to vary, so that in the above case a tubular part with 121 cm with a catch bolt with 61 cm can be attached. Similarly, reinforcement systems can be used for recurrent rock be used or to detect ground movements in mines.

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Counter-force, in which the tubular part is set deep into the rock and a removable part is attached to the catch pin Expansion piece is attached. Immediate support is therefore available when the tubular Part is installed. Subsequent removal of the expansion piece allows the Bottom and the reuse of the reinforcement part by an expansion piece with a shorter length is used.

The use of the tubular reinforcement member is also of value when it is buried relatively deep in the layer will. Thus, one can in a case where on a coal surface If a heavy load occurs, a significant improvement can be achieved if the tubular parts are deep installed in the layers in front of and above the coal fringe. For example, a 370 cm drill hole can be made at an angle be drilled through the coal and overlying rock. Then a tubular piece measuring 182 cm is inserted into the interior Inserted at the end of the borehole. The total length of the tubular Partly the track of the coal crusher is kept well, but still provides valuable support of the reason before the removal of the underlying supporting Money. In bad conditions it is possible to get a provide immediate reinforcement of the coal surface itself by drilling the outer 182 cm of the same borehole for the Insertion of a wood reinforcement dowel used.

The invention is illustrated in the examples. example 1

Three concrete blocks were arranged as shown in FIG. The blocks A and B were each 61.0 cm in length and diameter from Jf5> 7 cm. The block C had a length of 25 * t cm and a diameter of 15.2 cm. Blocks A and B were

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heavily reinforced with steel mesh and poured from concrete with a compressive strength of 352 kp / cm. As shown, a center hole with a diameter of l \ J> mm was drilled into the blocks. Cartridges with a diameter of i + 0 mm and a total weight of 110 g, which contained a reactively filled polyester resin filling compound, were inserted into the tube. The tubular part was then inserted, as shown in FIG. 1. The bolt was rotated at a speed of 500 rpm and pushed through the resin cartridges to release and mix the reactive ingredients. When the bolt was fully inserted into the hole, the resin completely filled the annulus between the hole and the annular part. A steel plate with a thickness of about 0.95 cm was placed over the free end of the bolt and fastened by inserting an ionically tapered steel piece, as shown in FIG. The resin composition gelled within 5 minutes from the insertion of the bolt. After one hour, a load was applied by means of two hydraulic jacks in such a way that blocks A and B were pulled from each other. A load exerted on this way very closely mimics the conditions that occur in subterranean rock formations due to the separation of stratified beds. The load was increased to 10 t without any noticeable movement of the attachment. As the load increased, the ingot expanded steadily to the extent that the two blocks were forcibly moved away from each other. The Gesai.'itausdehnung of the tube was determined to be 23 h cm. A buckling and a final tensile break finally took place under a load of 16 t.

Example 2

From a tube welded from mild steel, a tubular reinforcement part according to FIG. 4 was produced, the one

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It had an outer diameter of 37 mm and an inner diameter of 31.5 mm. A rolled thread was formed at each end over a length of 150 mm so that the diameter was increased to 38.6 mm. The pipe was closed with a pressed steel cap that was tack welded in place. The pipe, with a total length of 1.8 m, was installed in a borehole with a diameter of if 3 mm in the laminated slate roof of a mine driveway. Sufficient resin cartridges were inserted into the well before the pipe was installed to ensure that the annular space between the pipe and the hole was then filled with the resin compound. The borehole was drilled approximately ί \ Ο mm shorter than the length of the pipe so that a piece of pipe remained protruding from the mouth of the hole after installation. A square steel plate approximately 200 mm long and 10 mm thick was drilled in the center with a 39 km diameter hole so that the plate fit smoothly over the overlapping rolled threaded end of the pipe. The plate was made in firm contact with the roof of the driveway using a tapered steel wedge approximately 30 mm long, with a minimum diameter of ~ j> 0 mm and a maximum diameter of y? ram attached. After the plate had slid over the protruding end of the pipe, the wedge was inserted into the end of the pipe and secured with a hydraulic ram generating a pressure of 1 ton, the end of the pipe being expanded inside the plate.

In this way, a pattern of reinforcement pipes was installed along a stretch of the driveway to give a pipe density of one pipe per square meter of exposed roof surface result. The pattern was progressing along the driveway as soon as possible after releasing the fresh roof Installed. In this way a total length of Route reinforced by 50 m, with 250 tubular reinforcements

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parts, were used. The divergence of these supported Driveway was compared with a similar piece of the same driveway. Before and after the reinforced Zone measured. After the results it was seen that the support provided by the bound tubular Parts obtained had an effectively limited convergence of only about 1/10 of that in the not reinforced parts of the driveway was found.

Example 3

Annular reinforcement members of the type shown in Figure 4, described in Example 2, were installed in the overlying layers of coal to provide support prior to extraction of the coal. Under the prevailing conditions of this coal surface, the use of wooden dowels alone had not been found to be sufficient to limit the movement of the overlying layers, and it was found that the wooden dowels broke when sheared. For this reason, angle holes with a diameter of hj> mm were drilled through the coal surface into the overlying shale layer to a total depth of 3.5 m. The tubular members were then installed with the cartridges installed in the inner end of these holes and adequate amounts of resin used to fill the annular space between the tubular member and the hole. The tubular parts were 1.7 m in length, and once installed, the lower open end of the tube was closed by inserting a tapered hardwood plug. The remaining outer end of the borehole was then used for reinforcement by means of a solid wooden dowel with a diameter of J> 6 mm, which was also bound in position with a resin. In this way support was created within the slate above the coal and also within the coal itself. A pattern of tubular parts and

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Anchors of this type were transverse to the faulty surface of the
Coal surface installed with a spacing of approximately 0.5 m between the [boreholes. It was possible that the coal breaker could remove a strip of coal 600 mm deep in a single pass, cutting through the wooden dowels that lay in its path. After one pass of the machine the process was repeated and a second cough of V / inli holes was reinforced as
describe above. The process was repeated in this way after each pass of the machine until the basic conditions had improved. In this way, the operation of the coal cutting device was facilitated.

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Claims (9)

Claims 1. Process for consolidating fragile rock strata, characterized in that a tubular Reinforcement part with widened end parts fastened in a borehole, which penetrates the fragile rock layers has been drilled, the diameter of the borehole is dimensioned so that between the Yfand of the borehole and the Body part of the reinforcement part creates an annular gap of at least 2 mm. 2. The method according to claim 1, characterized in that there is an annular space of 3 to 5 mm. 3. The method according to claim 1 or 2, characterized in that one uses a tubular reinforcement part, the enlarged end part of which protrudes from the mouth of the borehole when the tubular part has been inserted therein, and that a base plate in contact with the protruding end part Rock is attached, which is adjacent to the mouth of the borehole. 4. The method according to claim 3, characterized in that that the projecting end part is provided with means to fix the base plate in position. -17-209839 / 07B9 5. The method according to claim 1 to 4, characterized in that there is a tubular reinforcing part made of metal or an alloy, preferably made of steel. 6. The method according to claim 1 to 5, characterized in that there is a tubular reinforcing part used, which is provided with a longitudinally extending indicator rod therefrom which is attached to the inner end portion of the Part is attached and which protrudes from the other band part of the part in such a way that it extends longitudinally in use of the tubular part can display. 7. The method according to claim 1 to 6, characterized in that the tubular reinforcement part in attached to the borehole with a resin composition based on polyester. 8. The method according to claim 7, characterized in that there is used a resin composition in a or multiple multicomponent single-compartment cartridges are contained, which are inserted into the borehole prior to insertion of the tubular Reinforcement member have been inserted, the latter having been rotated to set the contents of the cartridges in situ and mix. 9. The method according to claim 8, characterized in that that a sufficient number of cartridges are used, 209839/0759 ~ ¹⁸ ~ by the annular distance between the wall of the borehole and the tubular reinforcement part substantially completely to fill with the resin mass. 209839/0759