Low-permeability rock mass presplitting grouting long anchor cable construction method

Abstract

The invention discloses a low-permeability rock mass presplitting grouting long anchor cable construction method. The method comprises the steps that S1, a rock drilling roadway is excavated in the upper portion of a to-be-supported area; s2, presplitting holes are excavated from the rock drilling roadway to the lower middle section of the to-be-supported area; s3, a fan-shaped anchor cable hole is constructed in surrounding rock of the area to be supported, and an anchoring agent is installed at the bottom of the hole; s4, hollow grouting anchor cables are anchored and installed in the anchor cable holes; s5, a stop-grouting plug is installed in the anchor cable hole, and a tray and a lock of the anchor cable are installed; s6, pre-splitting blasting is conducted on the pre-splitting hole, and then a grouting hole and a stop-grouting plug are installed in the empty hole; s7, grouting holes formed in empty holes of the anchor cable hole and the pre-splitting hole are used for grouting in the holes at the same time, and then the grouting holes are blocked through screwed plugs; according to the application, the permeation range of the slurry in the rock is enlarged, so that the integrity of the rock mass is improved through grouting, and the stress state of the rock mass is improved; the grouting anchor cable construction quality of the low-permeability rock mass can be improved, and the permeation range of grout in surrounding rock is widened.

Description

Technical Field

[0001] The present invention relates to the technical field of ore mining, and in particular to a construction method for pre-splitting grouting long anchor cables in low-permeability rock masses. Background Art

[0002] When supporting low-permeability fractured rock masses, due to the presence of cementing agents such as clay minerals in the structural planes and fracture zones of the rock masses, the originally fractured surrounding rock is cemented together, resulting in a decrease in permeability and the surrounding rock will quickly fracture and collapse after exposure. The conventional grouting anchor cable construction method cannot spread the grout widely in the rock structure, resulting in poor grouting effect and thus unable to improve the stress state of the surrounding rock. Therefore, the anchor cable construction cannot achieve environmental reconstruction of the fractured surrounding rock. In this case, it is usually necessary to redesign the support method and use methods including steel arch frames, resin anchor cables, etc. for support, but these methods cannot fundamentally consolidate the originally fractured surrounding rock together.

[0003] Publication No. CN202311805344.5 provides a construction method for grouting anchor cables on the foundation pit slope in soft soil areas based on shear-resistant cement curing agents. Water, cement, and curing agents are stirred and mixed in a mixer to form a grout as the injection liquid and injected into the injection holes, and the anchoring force is improved by increasing the bonding force between the anchor cable and the surrounding soil; this method can protect the roof from blasting damage to the greatest extent before support, but only improves the anchoring effect of the grouting anchor cable by jointly controlling or improving the composition of the grouting liquid. However, for low-permeability rock masses, it cannot play a role in improving the integrity of the surrounding rock and the stress state of the surrounding rock. Summary of the Invention

[0004] In order to improve the integrity of the surrounding rock and the stress state of the surrounding rock for low-permeability rock masses, the present application provides a construction method for pre-splitting grouting long anchor cables in low-permeability rock masses.

[0005] The present application provides a construction method for pre-splitting grouting long anchor cables in low-permeability rock masses, and adopts the following technical solutions:

[0006] A construction method for pre-splitting grouting long anchor cables in low-permeability rock masses includes the following steps:

[0007] S1. Excavate a drilling roadway in the upper part of the area to be supported;

[0008] S2. Drill pre-splitting holes downward from the drilling roadway to the middle section of the area to be supported;

[0009] S3. Construct fan-shaped anchor cable holes in the surrounding rock of the area to be supported and install anchoring agents at the bottom of the holes;

[0010] S4. Install a hollow grouting anchor cable in the anchor cable hole for anchoring;

[0011] S5. Install a grout stopper in the cable anchor hole, and install the tray and locking device of the cable anchor.

[0012] S6. Carry out presplitting blasting on the presplitting holes. After presplitting blasting, install grouting holes and grout stoppers in the empty holes.

[0013] S7. Grout into the holes simultaneously through the grouting holes arranged in the empty holes of the cable anchor holes and the presplitting holes. After grouting is completed, seal the grouting holes with a plug.

[0014] Optionally, in step S1, the position of the rock - drilling roadway is directly above the area to be supported.

[0015] Optionally, in step S2, the plane of the presplitting holes intersects with the plane of the cable anchor holes, and the intersection angle is 5 - 15°.

[0016] Optionally, in step S3, the thickness of the anchoring agent is 0.6 - 0.8 m.

[0017] Optionally, in step S7, the grouting pressure is 1 MPa until the grout overflows at the hole mouth, indicating that the grouting is completed.

[0018] In summary, the present application includes the following beneficial technical effects:

[0019] By pre - splitting and blasting the rock mass in advance, the present invention improves the degree of crack development in the rock mass through the existence of pre - cracks and presplitting blast holes, and simultaneously carries out forced grouting in the presplitting holes and cable anchor holes, thereby increasing the penetration range of the grout in the rock, improving the integrity of the rock mass through grouting, and improving the stress state of the rock mass. Applying this invention can improve the construction quality of grouted cable anchors in low - permeability rock masses and increase the penetration range of the grout in the surrounding rock. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the front view of the typical application of the present invention;

[0021] Figure 2 is Figure 1 the side view of;

[0022] Description of the reference numerals:

[0023] 1. Roadway to be supported; 2. Rock - drilling roadway; 3. Surrounding rock; 4. Area to be supported; 5. Anchoring agent; 6. Presplitting hole; 7. Bolt. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following further Figure 1-2 describes the present application in detail with reference to the attached drawings.

[0025] The embodiment of the present application discloses a construction method for pre-splitting grouting long anchor cables in low-permeability rock masses. First, in the upper area of the area to be supported 4, a drilling roadway 2 is excavated above the area to be supported 4 (if there are already corresponding engineering works in the upper and lower levels, they can be directly utilized), and pre-splitting holes 6 are drilled from the drilling roadway 2 to the current level to artificially create a slurry penetration space in the low-permeability surrounding rock 3. Then, the anchor cable holes are drilled from the roadway of the current level. Anchor cables are installed in the anchor cable holes and anchored with an anchoring agent 5 at an anchoring length of 0.6 - 2 m. The anchor cables are hollow grouting anchor cables. After the anchoring agent 5 takes effect for 30 minutes, grout plugs are installed in the anchor cable holes and the pre-splitting holes 6. After the grout plugs are installed, trays and locks are installed, and then the anchor cables are tensioned, followed by the grouting operation. Both the pre-splitting holes 6 and the anchor cable holes are used as grouting holes for grouting into the holes. When leakage occurs in the anchor cable holes, the grouting in the anchor cable holes is stopped. When the slurry leaks out from the pre-cracks in the pre-splitting holes 6, the grouting in the pre-splitting holes 6 is stopped. The grouting pressure is 1 MPa.

[0026] The specific implementation steps of the construction method for pre-splitting grouting long anchor cables in low-permeability rock masses in the embodiment of the present application are as follows:

[0027] First, a drilling roadway 2 is excavated in the upper part of the area to be supported 4, and the position of the drilling roadway 2 should be directly above the area to be supported 4;

[0028] A drilling roadway 2 is excavated in the upper part of the area to be supported 4, and then pre-splitting holes 6 are drilled from the drilling roadway 2 to the area to be supported 4 in the lower level. The row surface of the pre-splitting holes 6 should intersect with the row surface of the anchor cable holes, and the intersection angle is 5 - 15°;

[0029] Fan-shaped anchor cable holes are constructed in the surrounding rock 3 of the area to be supported 4. An anchoring agent 5 with a length of 0.6 - 0.8 m is installed at the bottom of the hole. A hollow grouting anchor cable is installed in the hole and the anchor cable is anchored. The anchor cable is provided with a grouting pipe.

[0030] After the anchor cable is anchored, a grout plug is installed in the hole, and the tray and lock of the anchor cable are installed;

[0031] Pre-splitting blasting is carried out on the pre-splitting holes 6. After the pre-splitting blasting, grouting holes and grout plugs are installed in the empty holes;

[0032] Grouting is carried out into the holes simultaneously from the grouting holes arranged in the empty holes of the anchor cable holes and the pre-splitting holes 6. The grouting pressure is 1 MPa until the slurry overflows at the hole mouth, and a plug is installed at the tail of the hollow grouting anchor cable to block the position of the hollow grouting hole in the anchor cable.

[0033] The present application has the following beneficial effects;

[0034] (1) Good grouting effect

[0035] By grouting inward simultaneously through the pre-splitting holes 6 and the cable anchor holes, the grout can diffuse into the surrounding rock 3 along the pre-splitting cracks and the pre-splitting holes 6, increasing the flow range of the grouting liquid.

[0036] (2) The bonding property of the surrounding rock 3 is enhanced

[0037] Since the grouting liquid can actually flow in a large range in the low-permeability rock mass, it can bond the surrounding rock 3 in a larger range, thus preventing the cable anchor from failing due to the loosening of the surrounding rock 3.

[0038] (3) The integrity of the surrounding rock 3 is improved

[0039] The penetration of the cement slurry bonds the fractured surrounding rock 3, thus improving the integrity of the surrounding rock 3 and realizing the bonding and reinforcement of the fractured rock or soil mass.

[0040] (4) The anchoring force is increased

[0041] By artificially creating pre-splitting holes 6 and pre-splitting cracks in the low-permeability rock mass, forced grouting into the low-permeability rock mass is realized, greatly increasing the friction and bonding force between the cable anchor and the rock mass, thus effectively increasing the anchoring force.

[0042] The above are all preferred embodiments of this application. The protection scope of this application is not limited hereby. Therefore, all equivalent changes made according to the structure, shape, and principle of this application shall be covered within the protection scope of this application.

Claims

1. A method for constructing a long anchor cable for pre-splitting grouting of low permeability rock mass, characterized in that The steps include: S1. Excavate a rock tunnel in the upper part of the area to be supported; S2, drilling pre-splitting holes from the rock drilling tunnel to the lower middle section to be supported; S3. Construct fan-shaped anchor holes in the surrounding rock of the area to be supported and install anchoring agents at the bottom of the holes; S4. Anchor and install the hollow grouting anchor cable in the anchor cable hole; S5. Install the stopper plug in the anchor hole, and install the anchor tray and lock; S6, pre-splitting blasting is performed on the pre-splitting hole, and after the pre-splitting blasting, a grouting hole and a grout stopper are installed in the empty hole; S7. Grouting is simultaneously performed into the holes through the grouting holes arranged in the empty holes of the anchor holes and the pre-crack holes. After the grouting is completed, the grouting holes are sealed with wire plugs.

2. A low permeability rock mass pre-splitting grouting long anchor cable construction method according to claim 1, characterized in that: In step S1, the location of the rock drilling tunnel is located directly above the area to be supported.

3. A low permeability rock mass pre-splitting grouting long anchor cable construction method according to claim 2, characterized in that: In step S2, the row surface of the pre-splitting holes intersects with the row surface of the anchor holes, and the intersection angle is 5 to 15 degrees.

4. A low permeability rock mass pre-splitting grouting long anchor cable construction method according to claim 1, characterized in that: In step S3, the thickness of the anchoring agent is 0.6 to 0.8 m.

5. A low permeability rock mass pre-splitting grouting long anchor cable construction method according to claim 1, characterized in that: In step S7, the grouting pressure is 1 MPa until the slurry overflows from the orifice, which means that the grouting is completed.

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