CN102116162A - Tension dispersed anchor cable for coal mine and anchoring method thereof - Google Patents

Abstract

The invention discloses a coal mine tension dispersion type anchor cable and its anchoring method, which is composed of an anchor head section, a free section and an anchoring section, and is characterized in that the anchoring section is on different anchoring sections along the direction of drilling depth , using anchoring agents with different curing times, so that the anchoring agents placed at the same time on the different anchoring segments complete curing at different times; The segmental anchoring agent is cured first, and the anchoring agent on the outer anchoring segment that is closer to the drill hole and adjacent to it is 10 to 20 hours behind to complete the curing. The invention can effectively improve the stability and safety of roadway support.

Description

Coal mine tension dispersion type anchor cable and its anchoring method

technical field

The invention relates to an anchor cable used in coal mine support and an anchoring method thereof.

Background technique

With the deepening of coal mine construction and production level, the ground pressure of coal mine roadway increases; with the upgrading of coal mining technology and equipment, the section of coal mine roadway increases correspondingly, and anchor cable support is increasingly becoming a medium in high ground pressure and large cross-section roadways of coal mines. Indispensable means of support. Coal mine anchor cable support has changed from a short-term support method in the early stage of its research and application to a support method that is used both for short-term support and long-term support, from the popularization and application of supporting short-term service roadways to supporting long-term service roadways , From the popularization and application of supporting coal roadways to supporting rock roadways and even soft rock roadways.

However, the anchoring structure and technology of the coal mine roadway anchor cable support have not been modified along with the major changes in the coal mine roadway anchor cable support objects and conditions. Through the analysis, it can be found that there are certain systematic defects in the anchor cable anchoring technology of coal mines, and the existing anchor cable anchoring technology has certain systematic risks for the stability and safety of coal mine roadway support.

According to different bearing methods, anchor cables can be divided into tension-concentrated anchor cables, pressure-concentrated anchor cables, tension-dispersed anchor cables, pressure-dispersed anchor cables, and tension-compression mixed anchor cables. In coal mine roadway support, the commonly used anchor cables belong to tension-concentrated anchor cables. The anchoring structure of the tension-concentrated anchor cable consists of an anchor section A that solidifies and anchors at the same time, a free section B and an exposed anchor head section C, as shown in Figure 1a and Figure 1b, with the same curing performance The same anchoring agent is used to anchor the anchoring section A in the surrounding rock drilling, and the same anchoring agent with the same curing performance is used to complete the anchoring of the entire anchoring section in one drilling.

The research shows that the distribution of the bonded shear stress of the tension-concentrated anchor cable is not uniform, and only part of the length of the anchorage section is stressed; , the bonded shear stress of the anchor cable decays rapidly in an exponential curve; serious tensile stress concentration occurs at the outer end of the anchor section, that is, the initial position of the anchor section; Breaking force, so that the failure of the anchorage in the anchor cable will occur at lower anchorage force levels. Most of the traditional prestressed anchor cables belong to this type, and the anchor cable anchorage structures currently used in coal mine roadway support all belong to this type.

The failure and damage of the anchor cable support are hidden failures and hidden damage, and the existing monitoring technology is difficult to detect the damage of the anchorage in the anchor cable in time. Serious threats, specifically manifested in:

1. The working condition of the anchor cable looks good on the surface, but the roof has delamination and settlement, indicating that the inner anchor of the anchor cable has loosened or loosened.

2. After the anchor cable is sheared and damaged with the bonding medium or the hole wall, it loosens and pulls off, and the roof may have serious separation or collapse when the outer anchor of the anchor cable is intact;

3. Provide distorted information to roadway support designers, causing designers to attempt to improve the safety of roadway support by increasing the number of anchor cables installed or increasing the diameter of anchor cables in future support design;

4. Increase the cost of roadway support materials.

Contents of the invention

The present invention is to avoid the shortcomings of the above-mentioned prior art, and to provide a more uniform distribution of bonded shear stress in the anchorage section, and a longer effective length of the anchorage section of the anchor cable, which can effectively improve the stability and safety of roadway support. A permanent coal mine tension dispersion anchor cable and its supporting method.

The present invention solves technical problem and adopts following technical scheme:

The coal mine tension dispersion anchor cable of the present invention is composed of an anchor head section, a free section and an anchor section, and is characterized in that the anchor section adopts anchorage cables with different curing times on different anchor sections along the depth direction of the borehole. agent, so that the anchoring agent placed at the same time on the different anchoring segments completes curing at different times; and, the anchoring agent in the inner anchoring segment that is closer to the bottom of the drill hole solidifies first, The anchoring agent on the outer anchoring segment, which is closer to the borehole opening and adjacent to it, lags behind 10 to 20 hours to complete curing.

The feature of the anchoring method of the coal mine tension dispersion type anchor cable of the present invention is to carry out as follows:

a. Use a small-diameter anchor cable hole in which only one anchor cable is installed in each anchor cable hole;

b. Insert the anchoring agent into the small-diameter anchor cable hole, first insert the anchoring agent that has been cured at the position of the inner anchoring segment A1 first, and then insert the anchoring agent at the position of the outer anchoring segment A2 with a delay of 10 to 20 hours to complete the curing Anchoring agent;

c. Install the steel strand, and use the steel strand to continuously stir the anchoring agent until the specified stirring time;

d. When the anchoring agent at the A1 position of the inner anchoring segment is completely cured, install the anchorage and pre-tension it to the design tension;

e. Wait until the anchoring agent at the position of the outer anchoring segment A2 is fully cured after 10 to 20 hours.

Compared with the prior art, the beneficial effects of the present invention are reflected in:

1. Due to the use of anchoring agents with different curing speeds in the present invention, by setting the corresponding installation sequence, the anchoring agents of different anchoring segments in the same drilling hole can be solidified and anchored in different periods of time, thereby realizing the anchor cable The segmental and time-sharing anchoring improves the effective length of the anchoring section of the anchoring cable, disperses and evens the distribution of the shear stress of the anchoring section of the anchoring cable, reduces the peak value of the bonded shear stress of the anchoring cable, and improves the anchorage of the anchoring cable. Anchorage and support strength.

2. The present invention installs the anchor cable anchoring agent in the order of the anchoring agent with a shorter curing time first and the anchoring agent with a lagging curing time behind. Two or more anchoring agents with different curing speeds are installed at one time and stirred at one time. Thereby, the one-time installation and stirring of the small-aperture new tension dispersion type anchor cable can be completed, and the segmental and time-sharing anchoring can be realized.

Illustration

Fig. 1a is a schematic diagram of the anchoring structure of the tension-concentrated anchor cable in the prior art.

Fig. 1b is a schematic diagram of the bonded shear stress distribution of the tension-concentrated anchor cable shown in Fig. 1.

Fig. 2a is a schematic diagram of the structure of the present invention.

Fig. 2b is a schematic diagram of the shear stress distribution of the anchorage section of the present invention.

Detailed ways

Referring to Fig. 2a and Fig. 2b, the present embodiment is composed of anchor head section C, free section B and anchor section A, and anchor section A adopts different solidification time on different anchor sections along the drilling depth direction. Anchoring agent, so that the anchoring agent placed at the same time on different anchoring segments completes curing at different times; and, the anchoring agent in the inner anchoring segment A1 that is closer to the bottom of the drill hole is cured first, The anchoring agent on the outer anchoring segment A2 which is closer to the hole opening of the borehole and adjacent thereto completes solidification after a delay of 10 to 20 hours.

In the specific implementation of the present invention, the length ratio of the inner anchoring segment A1 to the outer anchoring segment A2 is generally 1:1, but the length of the inner anchoring segment A1 should not be less than 1 meter. Medium-speed anchoring agent is used for the inner anchoring segment, and retarded anchoring agent is used for the outer anchoring segment. The initial setting time of the retarding anchoring agent is 12 to 16 hours, and the final curing time is 24 hours.

Anchoring process:

1. Use a small-diameter anchor cable hole where only one anchor cable is installed in each anchor cable hole;

2. Insert the anchoring agent into the anchor cable hole, first place the anchoring agent that has been cured at the position of the inner anchoring segment A1 first, and then insert the anchoring agent that has been cured at the position of the anchoring segment A2 with a delay of 10 to 20 hours;

3. Install the steel strand, and at the same time use the steel strand to continuously stir the anchoring agent until the specified stirring time;

4. When the anchoring agent at the A1 position of the inner anchoring segment is completely solidified, install the anchor and pre-tension it to the design tension;

5. Wait for the anchoring agent at the position of the outer anchoring segment A2 to be fully cured after 10 to 20 hours.

Bearing process:

At the initial stage of installation, the anchoring agent at the outer anchoring segment A2 is not stressed because it has not been solidified, and the anchoring force of the anchor cable is all generated at the position of the inner anchoring segment A1;

As the roof pressure increases, the anchoring force of the anchorage section on the anchor cable will increase accordingly;

When the anchoring agent at the outer anchoring segment A2 of the anchor cable is completely solidified and anchored, and the load of the roof acting on the anchor cable is greater than the anchoring force at the inner anchoring segment A1, the anchoring force at the outer anchoring segment A2 begins to generate and growth, at this time, the force at the inner anchorage segment A1 will not increase;

When the load acting on the anchor cable by the top plate is greater than the anchoring force at the outer anchoring segment A2, and the anchoring force at the inner anchoring segment A1 has not reached its maximum anchoring force, the anchoring force at the inner anchoring segment A1 will still change with increase with the increase of roof pressure until reaching its maximum anchoring force;

After both the inner anchoring segment A1 and the outer anchoring segment A2 have been anchored, the anchoring force of the anchor cable is equal to the sum of the anchoring forces at the inner anchoring segment A1 and the outer anchoring segment A2.

Claims (3)

1. Coal mine tension dispersion type anchor cable, which is composed of anchor head section, free section and anchor section. agent, so that the anchoring agent placed on the different anchoring segments at the same time completes curing at different times; and, the anchoring agent in the inner anchoring segment A1 that is closer to the bottom of the drill hole is cured first , the anchoring agent on the outer anchoring segment A2 which is closer to the drill hole opening and adjacent to it lags behind for 10 to 20 hours to complete curing. 2. The coal mine tension dispersed anchor cable according to claim 1, characterized in that the length ratio of the inner anchor segment A1 to the outer anchor segment A2 is 1:1, and the length of the inner anchor segment A1 should not be less than 1 meter. 3. an anchoring method of the described coal mine tension dispersion type anchor cable of claim 1, it is characterized in that carry out as follows: a. Use a small-diameter anchor cable hole in which only one anchor cable is installed in each anchor cable hole; b. Insert the anchoring agent into the small-diameter anchor cable hole, first insert the anchoring agent that has been cured at the position of the inner anchoring segment A1 first, and then insert the anchoring agent at the position of the outer anchoring segment A2 with a delay of 10 to 20 hours to complete the curing Anchoring agent; c. Install the steel strand, and use the steel strand to continuously stir the anchoring agent until the specified stirring time; d. When the anchoring agent at the A1 position of the inner anchoring segment is completely cured, install the anchorage and pre-tension it to the design tension; e. Wait until the anchoring agent at the position of the outer anchoring segment A2 is fully cured after 10 to 20 hours.

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