RU2584990C2 - Method of fastening cable anchor - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention relates to mining, particularly to a method of installing anchors to secure walls and roof in mines or tunnel. Disclosed is a method of fixing cable anchors in blast hole drilled in soil formation comprising following steps: provision of cable anchors injection pipe and injection of adapter, containing inlet of resin component, static mixer and outlet for mixed resin; introduction of cable anchors and injection pipe in drilled bore pit so that end of injection tube is located on distal end of bore pit or near it; compound injection of adapter with injection pipe; and pumping of multi-component resin system through injection adapter in drilled bore pit so that static mixer injection adapter mixes system of multicomponent resin for fixation of hardened resin cable anchors in drilled hole.

EFFECT: reduced time of installation of anchors.

6 cl, 4 dwg, 1 tbl

Description

The present invention relates to a method for securing a cable anchor in a soil formation.

A cable anchor is used in the mining industry and in construction to strengthen soils or rocks in order to fix steep sides or roofs, walls or work horizons in a mine or tunnel. Typically, cable anchors are used to fix soil formations in difficult conditions, for example, where drilled holes with a diameter greater than the nominal or in conditions of fractured and / or washed formations.

Cable anchors are usually secured in place using a cement or polymer based mortar filling system. It is difficult to find a solution pouring system that would be pumped for a sufficient time and then quickly and with sufficient efficiency would provide the necessary strength of the cable anchor without additional quick hardening. Pouring cement mortar cable anchors often faced with problems of quality assurance and quality control, which is associated with the cementation process. Pouring cement mortar is a relatively complicated procedure, as it is necessary to install a ventilation pipe and block the hole in the hole with bottomhole material in order to prevent leakage of uncured cement. As a rule, when using a cable anchor with cement mortar, cement needs more than 24 hours to solidify before further work can be carried out in the area of the cable anchor.

As an alternative to the solution injection system, the use of resin cartridge support is known. However, even with standard anchor bolts, resin cartridge support is ineffective in difficult conditions in which cable anchors are usually used. Cable anchors are less suitable for use with resin cartridges because it is difficult to ensure that the cable anchor passes through the resin cartridge and mixes its contents correctly.

Thus, there is a need for a system for quickly installing cable anchors without the usual long delays associated with curing cement slurry.

According to the invention, a method for securing a cable anchor in a hole drilled in a soil formation is proposed, comprising the following steps:

providing a cable anchor, injection pipe and injection adapter according to the invention;

introducing a cable anchor and an injection pipe into the drilled hole so that the end of the injection pipe is located at or near the distal end of the hole;

connecting the injection adapter to the injection pipe; and

pumping the multicomponent resin system through the injection adapter into the drilled hole so that the static mixer of the injection adapter mixes the multicomponent resin system to secure the hardened resin to the cable anchor in the drilled hole.

The advantages of the invention are that the use of an injection adapter with a resin ensures good mixing of the resin and the correct installation of the anchor. Suitable for pumping multicomponent resins for fastening anchor bolts provide significant advantages compared to traditional resin cartridges and cement grout injection systems, where fast and easily adaptable support for difficult soil conditions is required. This is because multicomponent resins, as a rule, harden faster than cementing systems. When using the injection adapter according to the invention, the resin is pre-mixed before it is introduced into the drilled hole so that the resin hardens and begins to harden before it is introduced. As a result, it is not necessary to block the drilled hole with the bottomhole material, since the thickened resin will not flow out of the drilled hole, even if the hole is drilled in the roof of the tunnel. Since downhole material is not required, a ventilation pipe is also not required, which simplifies the installation procedure compared to cable anchoring using cement mortar. As a rule, well-known multi-component resin systems harden in less than an hour, which allows fixing and tensioning of cable anchors much faster after their installation. This quick installation process allows you to prepare the mine plane after installation much faster. Quick installation allows you to immediately continue work on the soil formation without damage or negative impacts for mortar-filled anchors. Saving time per cycle is a minimum of 24 hours, which is a typical minimum wait for non-shrink cement mortars.

In some embodiments, the multi-component resin system is a two-component resin system in which the first component contains isocyanate and the second component contains silicate. The advantages of using a two-component resin system containing an isocyanate prepolymer and silicate are that it provides fast solidification strength sufficient to hold anchor fastening in a drilled hole without additional support. It also has a high flash point, low flammability and high oxygen index. In addition, the supply pipes and pump used for the second component of the resin system can be cleaned using water, as the silicate is soluble in water. Such a resin system hardens very quickly, since it sets in less than one minute after injection and allows the cables to be fixed and tensioned less than ten minutes after installation of the cable anchor.

In some embodiments, the bicomponent resin system may be a bicomponent silicate resin system sold by Minova Australia Pty Ltd under the trademark "CARBOTHIX", the advantages of which are:

the volume ratio of the system is one part of silicate to two parts of the isocyanate prepolymer, which facilitates the injection and maintenance of the ratio (but alternative volume ratios between 1: 1 and 1: 3 can also be used);

the system does not include a filler, so that there are no solid particles capable of clogging the pump or other lines used for injection of the resin system;

the system has a low viscosity (approximately 200-400 cP), so it is easy to pump;

exclusion of refrigerated storage of polyester resins in order to increase shelf life;

variable injection to ensure complete encapsulation of anchor bolts;

checks for the content of isocyanates showed that they are not detectable or well below the minimum limiting thresholds.

In some embodiments, the volumetric ratio of the components of the multicomponent resin system can be selected so that the resin does not completely harden in less time than is required to pump the resin system into the borehole. Since the volume ratio can be selected by the pump operator for the multi-component resin system, one skilled in the art can determine the appropriate ratio and knows that the curing time was too long because the resin was not sufficiently thickened when filling the hole. The person skilled in the art will also determine if the curing time was too short and the resin solidified in the hole before it was filled with resin. The selection of the ratio will depend on factors such as the size of the drilled hole due to the looseness of the soil formation, the presence of cracks or other defects, ambient temperature, pressure and humidity and / or the type of soil formation.

In some embodiments, the implementation of the static mixer has at least 10 elements. For example, a static mixer may have from 10 to 48 elements, in particular about 30 elements. When using the Carbothix® resin system, such a large number of elements is necessary to provide high mixing energy. Incomplete mixing of this system can be easily detected since the resin foams upon hardening.

In some embodiments, the cable anchor may be further secured with a wire mesh. In some embodiments, the cable anchor may have any of the features that are common in cable anchor technology, and may have any length in the area of typical cable anchors. The term "soil formation" means the mass of rocks, earth and / or soil in embankments, quarries, mines or tunnels.

The invention is further illustrated with reference to the following drawings, which are presented to illustrate the claimed invention, but not to limit the scope of protection.

In FIG. 1 shows a schematic view of an injection adapter according to the invention,

In FIG. 2 shows a schematic view of a system according to the invention,

In FIG. 3 shows a schematic view of a fixed cable anchor according to the invention.

In FIG. 4 shows an alternative embodiment of a fixed cable anchor according to the invention.

In FIG. 1 shows an injection adapter 10 according to the invention. The adapter 10 is made in the form of a pipe 20, which has an inlet 30, a static mixer 60 located in the pipe 20 near the inlet 30, an internal channel 50 and an outlet 40. The inlet 30 is mainly located at the end of the injection adapter 10 and is adapted for connection with a pump of multicomponent resins. The outlet 40 is generally located at the end of the injection adapter 10 and is adapted to be connected to the injection pipe. The injection adapter 10 is usually less than 1 meter long, as a rule, its length is from 40 cm to 60 cm, for example 45 cm.

In FIG. 2 shows a system 100 according to the invention. System 100 comprises an injection adapter 10, as shown in FIG. 1, a cable anchor 15, an injection pipe 25 and a two-component resin system 70. The two-component resin system 70 contains a first isocyanate component 80 and a second silicate component 90. The cable anchor 15 has a length of 3 m to 10 m, for example 5 m. Injection pipe 25 As a rule, it has a length of 2 to 5 m, for example, about 3 meters.

In FIG. 3 shows a fixed anchor 200 according to the invention. In FIG. 3 shows a soil formation 120 in the form of a stone wall. A drill hole 110 is shown in the stone wall 120, in which a cable anchor 15 is attached to the multi-component resin system 75. The multi-component resin system 75 has been pumped into the drill hole 110 by means of an injection adapter 10 and an injection pipe 25.

The method of securing the cable anchor 15 in the soil formation 120 comprises the following steps.

After preparing a soil formation, such as excavating a tunnel, a hole is drilled in the soil formation to create a drilled hole 110. The drilled hole 110 has a proximal end 112 located at the hole of the hole and a distal end 114. Then the cable anchor 15 is inserted into the drilled hole 110 with an injection pipe 25, the injection adapter 10 is connected to the injection pipe 25, and the multi-component resin pump can be connected to the injection adapter 10 before or after this connection. Then, the multicomponent resin system 75 is pumped through the injection adapter 10, while the static mixer 60 in the injection adapter 10 thoroughly mixes the components of the resin system. When the resin system begins to thicken, it is pumped through the injection pipe to fill the drilled hole 110 from the distal end. Then, the multicomponent resin system 75 hardens and secures the cable anchor 15 in place to strengthen the soil formation 120.

In an alternative embodiment, the cable anchor may have a mechanical sheath to preload the cable anchor 15 before injecting the resin system to encapsulate the cable anchor 15.

In FIG. 4, a fixed mountain tunnel 200 is shown. The mountain tunnel has a width of 5.0 m and a height of 5.3 m. It is located in the soil formation 205, mounted on each of the vertical walls 206 and 207 with three anchor bolts 220. The roof 208 is fixed with five cable anchors 220 To further secure the mountain tunnel 200, a metal wire mesh 209 is provided.

EXAMPLE 1

Tests were carried out on the method and system according to the invention in the form of a dynamic support system in order to worsen soil conditions, including deformation explosion.

Tests were conducted in veins with a high copper content, where drilling in soft and loose ores can lead to a significant excess of the nominal size of the holes.

In difficult places of the copper mine, cable anchors were installed according to the method of the invention. A quick set of Minova Carbothix® resins with a 1: 1 ratio of silicate to isocyanate and a cure time of about 1 minute was used with a 5-meter cable anchor. In some areas where drilled holes intersected with cracks formed under the influence of stress or passed along structural features, problems arose with the holes being completely filled before a significant increase in the discharge pressure, which indicated the solidification of the resin. With experienced operators, this was a limited case, but a solution was needed. In such areas, Minova Carbothix® resin was used with a curing time of 3-4 minutes.

COMPARATIVE EXAMPLE 2

For comparison, cable anchors were installed in a known manner by pouring cement mortar in places similar to example 1.

For extended support in holes 3-10 meters deep, double 16 mm steel cable anchors were used. Before installing the cable anchor in the drilled hole, the plastic ventilation pipe was attached to the cable anchor so that the pipe reached the distal end of the drilled hole. A cable anchor and a ventilation pipe were inserted into the hole, and, in addition, a large diameter cement mortar pipe was installed in the hole to a depth of about 0.6 m. After that, the entire hole around the cable anchor, grout and ventilation pipe was sealed with bottomhole materials and spray foam to prevent cement from flowing out of the hole. Then, the hole was filled with cement pumped through the hole in the hole. When the cement reached the end of the hole, it burst from below into the vent pipe. If cement was detected at the proximal end of the ventilation pipe, the cement pump was stopped. It took a minimum of 24 hours to harden the cement before the cable anchor could be fixed and tensioned with a force of about 10 tons.

Thus, it becomes apparent that the known method is much more complex than the method according to the invention and requires more time. The use of the resin injection adapter according to the invention eliminates the need for ventilation pipes, since the drilled hole is filled from the back to the front. There is no need to drill the holes of the drilled hole, since the resin is thixotropic and does not even flow out of vertical holes. The resin is supplied in accordance with a constant volumetric ratio from the pump, it fills the voids, strengthens the fractured soil and hardens immediately, which allows fixing and tensioning within 10 minutes.

EXAMPLE 3

In tests, it was found that when using the Carbothix® system as a two-component resin system 70 after 6 minutes, the shear force is 75% greater than when using a non-pumpable version of the polyester resin. After 10 minutes, shear strength is 100% greater. It was found that the Carbothix® system with stirring has an average maximum exothermic temperature of 97 ° C for a cure time of about 4 minutes, which meets the requirements of MDG 3006 MRT8 (design, January 2007) Section 5.1 a) for maximum exothermic temperature. It also established compliance with the requirements of MDG 3006 MRT 8 (draft, January 2007) section 5.1 b), c), d), e) and f) for electrical resistance, fire resistance (after contact with the burner flame for 60 seconds, preservation the flame on the sample of the Carbothix system lasted a maximum of 2 seconds, showing low combustibility), the spread of fire, the ignition temperature (during tests it was not possible to determine the ignition temperature, as it was above 100 ° C) and the determination of the chemical characteristics of the resin components, respectively.

The Minova Resin Injection System has been found to provide complete encapsulation of the anchor, eliminating the question of whether the resin cartridges were mixed correctly to install the anchors according to design.

EXAMPLE 4

The properties of the bicomponent resin system 70 using Carbothix® were compared with those of Minova Australia Pty Ltd, Geoflex®. The results obtained are presented below in table 1, which shows that Carbothix® showed a high shear strength and bending strength at any time after curing.

Claims (6)

1. A method of securing a cable anchor in a hole drilled in a soil formation, comprising the following steps:
providing a cable anchor, an injection pipe and an injection adapter comprising an inlet for the resin component, a static mixer and an outlet for the mixed resin;
introducing a cable anchor and an injection pipe into the drilled hole so that the end of the injection pipe is located at or near the distal end of the hole;
connecting the injection adapter to the injection pipe; and
pumping the multicomponent resin system through the injection adapter into the drilled hole so that the static mixer of the injection adapter mixes the multicomponent resin system to secure the hardened resin to the cable anchor in the drilled hole. 2. The method of claim 1, wherein the multi-component resin system is a two-component resin system in which the first component contains isocyanate and the second component contains silicate. 3. The method according to claim 1 or 2, in which the two-component resin system is the CARBOTHIX system. 4. The method according to p. 1, which further comprises the step of securing the cable anchor using a wire mesh. 5. The method according to p. 1, in which the soil formation is a mass of rocks, earth and / or soil in embankments, quarries, mines or tunnels. 6. The method of claim 1, wherein the static mixer has at least 10 elements.

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