A self-drilling combined bolt support method applicable to soft and fractured surrounding rock

Abstract

The present invention discloses a self-drilling combined bolt support method applicable to soft and fractured surrounding rock, including: drilling a hole at a preset position of the rock mass to be bolted; detecting the drilled hole to judge whether the support strength can be satisfied after supporting the rock mass to be bolted with a preset bolt, if not, arranging a pre-drilled bolt and a self-drilling bolt in the drilled hole, and injecting slurry into the drilled hole; after the slurry solidifies, continuing to drill the self-drilling bolt to a preset depth; injecting slurry into the self-drilling bolt. The self-drilling combined bolt support method applicable to soft and fractured surrounding rock proposed by the present invention ensures that when it is found that the preset anchoring method is insufficient during conventional support construction, the method of the present invention is quickly adopted for support, enabling the self-drilling bolt to be anchored deep into the rock mass, and can conveniently, safely, efficiently and quickly provide support for the anchored rock mass, avoiding the rock mass failure caused by insufficient traditional support strength, and this combined method can increase the grouting support range of the bolt and enhance the overall strength of the support.

Description

Technical Field

[0001] The present invention discloses a self-drilling combined bolt support method applicable to soft and broken surrounding rock, belonging to the technical field of anchoring support. Background Art

[0002] During the construction processes such as tunnel excavation, mining engineering, and slope engineering, in order to prevent the deformation, collapse, or instability of rock masses from endangering safety, a main support technology for strengthening rock masses is to use bolts. By means of the high-strength tensile capacity of the bolts arranged in the rock masses and the tight combination between the bolts and the grouting bodies and rock masses around them, the rock masses are strengthened to improve the integrity of the rock masses, control the deformation of the rock masses, and make them reach a stable and safe state. Conventional construction designs are carried out on the basis of surveys, and designs are often completed before construction. When the rock masses are excavated, due to stress release, the cracks in the rock masses open. When encountering soft and broken surrounding rock during construction, the support strength may be insufficient, resulting in surrounding rock failures such as spalling and rib spalling. Summary of the Invention

[0003] The purpose of the present application is to provide a self-drilling combined bolt support method applicable to soft and broken surrounding rock to solve the technical problem that the original designed support scheme cannot meet the support requirements due to the high degree of softness and fragmentation of the rock masses during the rock mass support process. To achieve the above purpose, the present invention proposes a self-drilling combined bolt support method applicable to soft and broken surrounding rock, and further measures are taken to strengthen the support. The specific scheme is as follows:

[0004] A self-drilling combined bolt support method applicable to soft and broken surrounding rock includes:

[0005] Drilling a hole at a preset position in the rock mass to be anchored;

[0006] Detecting the hole, and judging whether the support strength can be satisfied after supporting the rock mass to be anchored with a preset bolt. If not, arranging a pre-drilled bolt and a self-drilling bolt in the hole, and injecting slurry into the hole;

[0007] After the slurry solidifies, continuing to drill the self-drilling bolt to a preset depth;

[0008] Injecting the slurry into the self-drilling bolt.

[0009] Preferably, before arranging the pre-drilled bolt and the self-drilling bolt in the hole, it further includes:

[0010] Arranging a backing plate at the anchor head section of the pre-drilled bolt, and fixedly connecting the pre-drilled bolt with the backing plate;

[0011] The diameter of the backing plate is equal to the inner diameter of the hole, and the backing plate is perpendicular to the axis of the hole.

[0012] Preferably, before injecting grout into the borehole, it further includes: arranging a sleeve on the self-drilling anchor bolt, and one end of the sleeve is connected to the backing plate.

[0013] Preferably, there are multiple self-drilling anchor bolts;

[0014] The depth of the borehole is consistent with the length of the pre-drilled anchor bolt, and the lengths of the multiple self-drilling anchor bolts are inconsistent and all longer than the pre-drilled anchor bolt.

[0015] Preferably, the preset depth is the elastic zone and / or the virgin rock stress zone of the rock mass.

[0016] Preferably, there are multiple pre-drilled anchor bolts;

[0017] The anchor head section of the self-drilling anchor bolt passes through the backing plate;

[0018] The self-drilling anchor bolt is arranged in the space surrounded by multiple pre-drilled anchor bolts.

[0019] Preferably, the grout is sodium silicate grout, cement mortar and / or pure cement grout. [[ID=F23]]

[0020] Beneficial effects: A self-drilling combined anchor bolt support method applicable to soft and broken surrounding rock proposed by the present invention ensures that when the deficiency of the preset anchoring method is found in the conventional support construction, the method of the present invention can be quickly adopted for support, enabling the self-drilling anchor bolt to be anchored deep into the rock mass, and can provide support for the anchored rock mass conveniently, safely, efficiently and quickly, avoiding the rock mass failure caused by insufficient strength of the traditional support, and this combined method can increase the grouting support range of the anchor bolt and strengthen the overall strength of the support. Description of the Drawings

[0021] Figure 1 It is a flow chart of the combined anchor bolt support method;

[0022] Figure 2 It is a schematic cross-sectional view of the combined anchor bolt support;

[0023] Figure 3 It is a schematic diagram of the support range of the combined anchor bolt.

[0024] In the figure: 1. Self-drilling anchor bolt; 2. Pre-drilled anchor bolt; 3. Sleeve; 4. Backing plate; I. Stress relaxation zone; II. Plastic strengthening zone; III. Elastic zone; IV. Virgin rock stress zone; A. Strong support area; B. Weak support area; C. Micro support area; D. Virgin rock area without support. Detailed Embodiments

[0025] To make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the protection scope of the present invention.

[0026] As Figure 1 shown, in one embodiment, a self-drilling combined bolt support method applicable to soft and broken surrounding rock is disclosed, including the following steps:

[0027] Step 1: Drill a hole at a preset position in the rock mass to be anchored. The drilling depth is the same as the length of the pre-drilled bolt 2, and the diameter of the drilled hole is larger than the diameters of all the pre-drilled bolts 2 expected to be placed in the hole. After the drilling is completed, the drill cuttings inside the hole will affect the setting of the bolt and the bonding quality of the subsequent grouting. Therefore, the hole is cleaned. Generally, after the final hole is drilled, the drill pipe is lifted a little, and the drill cuttings are discharged through the positive circulation by using the agitation of the drill bit.

[0028] Step 2: Detect the drilled hole. Generally, a direct observation method is used in combination with a ground penetrating radar to detect the rock mass to be anchored. According to the stress distribution state of the rock mass, the rock mass can be divided into four regions: stress relaxation zone I, plastic strengthening zone II, elastic zone III, and virgin stress zone IV. Judge the quality of the rock mass and set a threshold for the rock mass quality. If the detected rock mass quality is higher than the threshold, it is determined that the use of the pre-drilled bolt 2 to support the rock mass to be anchored can meet the support strength, and the pre-drilled bolt 2 is directly used for support. If the detected rock mass quality is lower than the threshold, it is determined that only using the pre-drilled bolt 2 to anchor the rock mass to be anchored cannot meet the support strength, and then the combined bolt support method of the present invention is used to anchor the rock mass to be anchored. The combined bolt is divided into two parts: the pre-drilled bolt 2 and the self-drilling bolt 1. As Figure 2 shown, it is the cross-sectional view of the combined bolt after the support is completed in this embodiment. The specific construction steps of the combined bolt support are as follows:

[0029] Step 2.1: Set a backing plate 4 at the anchor head section of the pre-drilled bolt 2. The pre-drilled bolt 2 can be one or more. The anchor head section of the pre-drilled bolt 2 can pass through the backing plate 4 and be welded to the backing plate 4, or the pre-drilled bolt 2 can be fixedly connected to the backing plate 4 by using a nut fixation method on one side of the backing plate 4. The diameter of the backing plate 4 is equal to the inner diameter of the drilled hole, and the backing plate 4 is perpendicularly arranged in the drilled hole along the axis of the drilled hole. The backing plate 4 can fix the relative positions of the bolts, making the bonding quality of the pre-drilled bolt 2 with the grout and the rock mass higher after grouting.

[0030] In this embodiment, two pre-drilled bolts 2 are selected, and the pre-drilled bolts 2 are fixedly connected to the backing plate 4 by using a nut fixation method. The pre-drilled bolts are located in the stress relaxation zone I of the rock mass.

[0031] Step 2.2: Pass the anchor head section of the self-drilling anchor rod 1 through the backing plate 4. It is more convenient for the next construction operation to pass the self-drilling anchor rod 1 through the backing plate 4 than not to do so. The self-drilling anchor rod 1 can be one or more. The lengths of multiple self-drilling anchor rods 1 are inconsistent and are all longer than the pre-drilled anchor rod 2. The self-drilling anchor rod 1 is arranged within the anchorage range of the pre-drilled anchor rod 2 and can be at any position around the pre-drilled anchor rod 2. Preferably, the self-drilling anchor rod 1 is arranged within the space enclosed by multiple pre-drilled anchor rods 2.

[0032] In this embodiment, it is selected that the self-drilling anchor rod 1 passes through the backing plate 4 and two self-drilling anchor rods 1 are used. The lengths of the two self-drilling anchor rods 1 are inconsistent, and the two self-drilling anchor rods 1 are arranged in the middle of the two pre-drilled anchor rods 2.

[0033] Step 2.3: Place the pre-drilled anchor rod 2 arranged on the backing plate 4 and the self-drilling anchor rod 1 in the drill hole. After setting the anchor rods, re-clear the drill hole, and use the pump-suction reverse circulation to clear the hole with a conduit to prepare for grouting in the drill hole.

[0034] Step 2.4: Install sleeves 3 on all the self-drilling anchor rods 1 in the drill hole. One end of the sleeve 3 is connected to the backing plate 4. The sleeve 3 can protect the self-drilling anchor rod 1 from being cemented after the grout is injected.

[0035] Step 2.5: Inject grout into the drill hole around the sleeve 3. The grouting is carried out using a grouting pipe, and a grout stopper is set on the grouting pipe. Use a grouting pump to inject grout into the drill hole to ensure that the grout enters the rock mass fissures. The grout is sodium silicate grout, cement mortar or pure cement grout. In this embodiment, cement mortar is selected. As Figure 3 shown, after injecting grout into the drill hole in this step, a strong support area A is formed in the support area of the pre-drilled anchor rod 2.

[0036] Step 3: After the grout solidifies, continue to drill the self-drilling anchor rod 1 to the preset depth; the preset depth is the elastic zone III and / or the virgin rock stress zone IV of the rock mass.

[0037] In this embodiment, there are two self-drilling anchor rods 1. One of the self-drilling anchor rods 1 passes through the plastic strengthening zone II and enters the elastic zone III. As Figure 3 shown, after injecting grout into the self-drilling anchor rod 1 entering the elastic zone III, a weak support area B is formed in its support area. The other self-drilling anchor rod 1 passes through the elastic zone III and enters the virgin rock stress zone IV. As Figure 3 shown, after injecting grout into the self-drilling anchor rod 1 entering the virgin rock stress zone IV, a micro support area C is formed in its support area, and an un-supported virgin rock area D is formed in the virgin rock stress zone IV where the anchor head of the self-drilling anchor rod 1 is located. The above construction method enables the self-drilling anchor rod 1 to anchor into the deep rock mass and enhances the overall strength of the support.

[0038] Step 4: Inject grout into the self-drilling anchor rod 1. The rod body of the self-drilling anchor rod 1 is hollow. Inject grout into the rod to make the grout enter the deep rock mass fissures, cementing the anchor rod and the rock mass. The grout is water glass grout, cement mortar or pure cement grout. In this embodiment, pure cement grout is selected. Inject cement mortar into the sleeve 3.

[0039] A self-drilling combined anchor support method suitable for soft and broken surrounding rock proposed by the present invention ensures that when the deficiency of the preset anchoring method is found in the conventional support construction, the method of the present invention can be quickly adopted for support, enabling the self-drilling anchor rod to be anchored deep into the rock mass, and can conveniently, safely, efficiently and quickly provide support for the anchored rock mass, avoiding the rock mass failure caused by insufficient strength of the traditional support. Moreover, this combined method can increase the grouting support range of the anchor rod and enhance the overall strength of the support.

[0040] The above embodiments only represent one implementation mode of the present invention, and the description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be subject to the appended claims.

Claims

1. A self-drilling combined bolt support method applicable to soft and fractured surrounding rock, characterized in that, Including: Drill holes at the preset positions of the rock mass to be anchored, and the drilling depth is the same as the length of the pre-drilled anchor bolt; Detect the drill holes, and judge whether the support strength can be satisfied after supporting the rock mass to be anchored with the pre-drilled anchor bolt. If not, set the pre-drilled anchor bolt and the self-drilling anchor bolt in the drill holes, and inject slurry into the drill holes; Among them, judging whether the support strength can be satisfied after supporting the rock mass to be anchored with the pre-drilled anchor bolt. If not, setting the pre-drilled anchor bolt and the self-drilling anchor bolt in the drill holes specifically includes: Judge the rock mass quality, set the rock mass quality threshold. If the detected rock mass quality is higher than the threshold, it is determined that the support strength can be satisfied by using the pre-drilled anchor bolt to support the rock mass to be anchored, and directly use the pre-drilled anchor bolt for support; if the detected rock mass quality is lower than the threshold, it is determined that only using the pre-drilled anchor bolt to anchor the rock mass to be anchored cannot meet the support strength, then use the combined anchor bolt support method to anchor the rock mass to be anchored. The combined anchor bolt is divided into two parts: the pre-drilled anchor bolt and the self-drilling anchor bolt; After the slurry solidifies, continue to drill the self-drilling anchor bolt to the preset depth; Inject the slurry into the self-drilling anchor bolt.

2. The self-drilling combined bolt support method for soft and fractured surrounding rock according to claim 1, characterized in that, Before setting the pre-drilled anchor bolt and the self-drilling anchor bolt in the drill holes, it also includes: Set a backing plate at the anchor head section of the pre-drilled anchor bolt, and the pre-drilled anchor bolt is fixedly connected to the backing plate; The diameter of the backing plate is equal to the inner diameter of the drill hole, and the backing plate is perpendicular to the axis of the drill hole.

3. A self-drilling combined bolt support method for soft and fractured surrounding rock according to claim 2, characterized in that Before injecting the slurry into the drill hole, it also includes: set a sleeve on the self-drilling anchor bolt, and one end of the sleeve is connected to the backing plate.

4. The self-drilling combined bolt support method for soft and fractured surrounding rock according to claim 1, characterized in that, There are multiple self-drilling anchor bolts; The depth of the drill hole is the same as the length of the pre-drilled anchor bolt, and the lengths of the multiple self-drilling anchor bolts are inconsistent and are all longer than the pre-drilled anchor bolt.

5. A self-drilling combined bolt support method for soft and fractured surrounding rock according to claim 1, characterized in that The preset depth is the elastic zone and / or the in-situ stress zone of the rock mass.

6. The self-drilling combined bolt support method for soft and fractured surrounding rock according to claim 2, characterized in that There are multiple pre-drilled anchor bolts; The anchor head section of the self-drilling anchor bolt passes through the backing plate; The self-drilling anchor bolt is arranged in the space surrounded by multiple pre-drilled anchor bolts.

7. A self-drilling combined bolt support method applicable to soft and broken surrounding rock according to any one of claims 1-6, characterized in that, The slurry is sodium silicate slurry, cement mortar and / or pure cement slurry.

Images