A full-length anchor fixed point yielding support anchor and its application in tunnel support

Abstract

The present invention belongs to the field of coal mine roadway anchor support, and specifically relates to a full-length anchor fixed point pressure-yielding support anchor, comprising a lower rod body and an upper rod body provided with external threads, a connecting groove and a first connecting head being provided in sequence at the upper end of the lower rod body, a grouting channel being provided inside the lower rod body, a grouting hole being provided at the connecting groove, and the grouting hole being connected to the grouting channel; a hollow interior of the lower end of the upper rod body forming a receiving chamber that can accommodate the connecting groove and the first connecting head, the inner diameter of the lower end of the receiving chamber being enlarged to form a second connecting head, and the remaining portion forming a connecting chamber, which is threadedly connected to the first connecting head; when the anchor is screwed in, the lower rod body and the upper rod body move in similar directions. The present invention can achieve both full-length anchoring of the anchor and fixed-point pressure-yielding, the anchor can be directly rotated for anchor drilling and installation, and when delamination occurs in the roadway, a pressure-yielding effect is generated by the pressure-yielding structure, and then the rock layers above and below the delamination are connected by grouting, thereby improving the support effect.

Description

Technical Field

[0001] The invention belongs to the field of coal mine roadway anchor support, and particularly relates to a full-length anchor fixing point yielding support anchor and its application in roadway support. Background Art

[0002] Tunnels are safe passages for pedestrians, ventilation and transportation in coal mines. During the excavation process, the initial stress equilibrium state of the original rock is broken and redistributed, causing deformation and damage to the surrounding rock of the tunnel, which brings certain safety hazards to coal mining.

[0003] In terms of tunnel surrounding rock control, on the one hand, it is necessary to fully mobilize the bearing capacity of the tunnel surrounding rock, and on the other hand, certain support methods must be adopted to achieve reinforcement and stabilization of the tunnel surrounding rock. With the continuous development of tunnel surrounding rock support technology, various support methods have been developed, including wood support, masonry support, steel support, and anchor support. The application of these support methods not only effectively suppresses the deformation of the tunnel surrounding rock, but also strengthens the tunnel surrounding rock and better mobilizes the self-bearing capacity of the tunnel surrounding rock. Among them, anchor support is widely used due to its advantages such as low support cost, fast construction operation, and good control effect, and has achieved good surrounding rock control results.

[0004] As a high-strength, high-rigidity active support method, the full-length anchor bolt has high support stiffness and is highly sensitive to the deformation and damage of the tunnel surrounding rock. It can achieve timely support, inhibit the occurrence of unbalanced deformation of the tunnel surrounding rock, and reduce the deformation of the tunnel surrounding rock. On the other hand, it can reduce the prestress loss during the anchor support process, reduce the corrosion damage to the anchor bolt caused by factors such as mine water, increase the effective control range of the anchor support on the tunnel surrounding rock, and improve the durability of the anchor support system.

[0005] However, when supporting the tunnel, even if support methods such as anchor rods are used, deformation cannot be avoided. Sometimes, it is appropriate to allow the surrounding rock of the tunnel to deform to a certain extent and allow the anchor rods to adapt to this deformation. Further anchoring and reinforcement will be beneficial to further support after the surrounding rock is deformed. Therefore, compression anchor rods, especially anchor rods that can be grouting after compression, came into being.

[0006] However, due to the limitation of the yield structure, yield anchor rods are rarely used for full-length anchor rods. Although some existing technologies also use the yield structure for full-length anchor rods, the full-length anchor rods including the yield structure are troublesome to install, and need to drill holes before installing the anchor rods, resulting in the tightness of the anchor rod installation needs to be improved. In addition, the position of the yield structure is set arbitrarily, and the appropriate yield position is not selected based on the deformation of the rock formation. This will cause some yield structures to be unable to produce the yield effect, while the position where yield is required is not provided with the yield structure. Summary of the Invention

[0007] In response to the above technical problems, the present invention proposes a full-length anchor fixing point pressure-yielding support anchor rod, comprising a lower rod body and an upper rod body with the same outer diameter, wherein the outer periphery of the lower rod body and the upper rod body is provided with a continuous thread with the same rotation direction;

[0008] The outer diameter of the upper end of the lower rod body is reduced to form a connecting groove, and a first connector is provided at the upper end of the connecting groove, and the outer diameter of the first connector is larger than the outer diameter of the connecting groove and smaller than the outer diameter of the lower rod body; a grouting channel is provided inside the lower rod body, and a grouting hole is provided in the connecting groove, and the grouting hole is connected to the grouting channel;

[0009] The lower end of the upper rod body is hollow inside to form a accommodating chamber that can accommodate the connecting groove and the first connecting head. The inner diameter of the lower end of the accommodating chamber becomes larger to form the second connecting head, and the remaining part forms a connecting chamber, and the connecting chamber is threadedly connected to the first connecting head. When the anchor rod is screwed in, the threaded connection between the connecting chamber and the first connecting head causes the lower rod body and the upper rod body to move in similar directions.

[0010] Preferably, the grouting channel extends from the lower end of the lower rod body at least into the connecting groove.

[0011] Preferably, a slurry plug is provided at the lower end of the grouting channel, a nut and a pad are provided at the lower periphery of the lower rod body, and the nut and the periphery of the lower rod body are threadedly connected.

[0012] Preferably, the second connecting head and the connecting groove are threadedly connected, and the threaded connection between the connecting cavity and the first connecting head and the threaded connection between the second connecting head and the connecting groove can enable the lower rod body and the upper rod body to move toward and away from each other in a certain amount.

[0013] Preferably, the second connecting head can move to the lowermost end of the connecting groove.

[0014] Preferably, a drill bit is detachably or integrally formed at the top end of the upper rod body, and the outer diameter of the drill bit is not greater than the outer diameter of the upper rod body.

[0015] The present invention also proposes a full-length anchor fixing point pressure-yielding support anchor rod and a full-length anchor fixing point pressure-yielding tunnel support method, comprising the following steps:

[0016] S1: Determine the location of the separation layer in the upper roof of the tunnel, where the upper rock layer of the separation layer is defined as the first roof rock layer, and the lower rock layer is defined as the second roof rock layer;

[0017] S2: Design the required displacement of the upper rod relative to the lower rod based on the delamination at the anchor bolt installation location;

[0018] S3: Determine that the length of the lower rod is slightly greater than the length of the second roof rock layer;

[0019] S4: After the tunnel is constructed, the anchor bolt is directly rotated and drilled into the designed position of the tunnel roof, and the upper rod body is completely and only located in the first roof rock layer, and the lower rod body is only located in the second roof rock layer. The part exposed in the second roof rock layer is sleeved with a backing plate and then tightened with a nut;

[0020] S5: When the second roof rock layer is separated from the first roof rock layer, a filling material is injected into the separation layer from the grouting channel through the grouting hole.

[0021] Preferably, in step S2, the deflection value w1 of the first roof rock layer, the deflection value w2 of the second roof rock layer, and the maximum deflection value w3 that the second roof rock layer can withstand at the anchor rod installation position are determined;

[0022] Preferably, in step S2, if w 2≤ w3, then the displacement of the upper rod on the lower rod should not exceed w2-w1; if w 2＞ w3, then the displacement of the upper rod relative to the lower rod is designed not to exceed w3-w1.

[0023] Preferably, in step S2, one or more anchor rods are provided along the width direction of the tunnel according to the design.

[0024] Preferably, in step S5, a cementitious filling material is injected.

[0025] Beneficial technical effects: 1. The full-length anchor fixed point pressure-yielding support anchor rod of the present invention can realize both full-length anchoring of the anchor rod and fixed-point pressure-yielding. The full-length anchoring can improve the anchoring performance of the anchor rod, and the fixed-point pressure-yielding can allow the anchor rod to yield at the designed position, avoiding the problem that the pressure-yielding structure cannot yield.

[0026] 2. The full-length anchoring of the present invention allows the pressure anchor rod to be installed without drilling holes first. Instead, the anchor rod can be directly rotated and drilled for installation. The anchor rod itself can be drilled, and the installation of the anchor rod is achieved when it is drilled to the designed position.

[0027] 3. The anchor bolt's yielding structure utilizes a threaded connection, with the thread direction matching the bolt's external threads. During anchor bolt installation, the upper and lower rods are positioned close together, preventing leakage from the connecting groove. If delamination occurs later in the roadway, the yielding structure allows the upper and lower rods to move relative to each other, generating a yielding effect.

[0028] 4. The full-length anchor fixed point pressure-yielding tunnel support method of the present invention, combined with the full-length anchor fixed point pressure-yielding support anchor rod of the present invention, sets the pressure-yielding position at the separation position, so that the pressure-yielding position can play a pressure-yielding effect, and later connects the rock layers above and below the separation layer through grouting to improve the support effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the full-length anchor fixing point yielding support anchor bolt in a contracted state according to the present invention;

[0030] Figure 2 This is a schematic diagram of the full-length anchor fixing point yielding support anchor rod of the present invention in a partially yielding (extended) state;

[0031] Figure 3 This is a schematic diagram of the full-length anchor fixing point yielding support anchor rod of the present invention in a fully yielding (extended) state;

[0032] Figure 4 This is a schematic diagram of the initial state of the full-length anchor fixing point yielding support anchor rod of the present invention when supporting the tunnel;

[0033] Figure 5 Schematic diagram of the yielding state of the full-length anchor fixing point yielding support anchor rod of the present invention when supporting the tunnel;

[0034] In the figure, there are a slurry plug 1, a nut 2, a pad 3, a lower rod body 4, a connecting groove 41, a first connecting head 42, a grouting channel 43, a grouting hole 44, an upper rod body 5, a connecting cavity 51, a second connecting head 52, and a drill bit 6; a first roof rock layer 7, a second roof rock layer 8, a coal seam 9, a tunnel 10, and a separation layer 11. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to the accompanying drawings.

[0036] Example 1

[0037] like Figure 1-3 As shown, the present invention proposes a full-length anchor fixing point pressure-yielding support anchor rod, comprising a lower rod body 4 and an upper rod body 5 with the same outer diameter, wherein the outer periphery of the lower rod body 4 and the upper rod body 5 are provided with a continuous thread with the same rotation direction;

[0038] The outer diameter of the upper end of the lower rod body 4 is reduced to form a connecting groove 41, and the upper end of the connecting groove 41 (the upper top of the lower rod body 4) is provided with a first connecting head 42, the outer diameter of the first connecting head 42 is larger than the outer diameter of the connecting groove 41 and smaller than the outer diameter of the lower rod body 4; the lower rod body 4 is a hollow rod body, and a grouting channel 43 is provided inside. The hollow part of the lower rod body 4, that is, the grouting channel 43, extends from the lower end of the lower rod body 4 at least into the connecting groove 41, and in this embodiment, extends to the middle of the length direction of the connecting groove 41; the connecting groove 41 is provided with a grouting hole 44, and the grouting hole 44 is connected to the grouting channel 43. The lower end of the grouting channel 43 is provided with a grouting plug 1, and the outer periphery of the lower part of the lower rod body 4 is also provided with a nut 2 and a pad 3, and the nut 2 is threadedly connected to the outer periphery of the lower rod body 4;

[0039] The lower end of the upper rod body 5 is hollow to form a accommodating cavity that can accommodate the connecting groove 41 and the first connecting head 42. The inner diameter of the lower end of the accommodating cavity becomes larger to form a second connecting head 52, and the remaining part forms a connecting cavity 51. The inner diameter of the connecting cavity 51 is substantially the same as the outer diameter of the first connecting head 42. The connecting cavity 51 is threadedly connected to the first connecting head 42; the inner diameter of the second connecting head 52 is substantially the same as the outer diameter of the connecting groove 41, and preferably the second connecting head 52 is threadedly connected to the connecting groove 41, and the threaded connection between the connecting cavity 51 and the first connecting head 42 and the second connecting head 52 and the connecting groove The 41 threaded connection enables the lower rod body 4 and the upper rod body 5 to move toward and away from each other in a certain amount; and when the anchor rod is rotated and drilled through the threads arranged on the outer periphery of the lower rod body 4 and the upper rod body 5, the threaded connection between the connecting cavity 51 and the first connecting head 42 and the threaded connection between the second connecting head 52 and the connecting groove 41 enable the lower rod body 4 and the upper rod body 5 to move in similar directions; the second connecting head 52 can move to the lowest end of the connecting groove 41; a drill bit 6 is also detachable or integrally provided at the top end of the upper rod body 5, and the outer diameter of the drill bit 6 is not larger than the outer diameter of the upper rod body 5.

[0040] Example 2

[0041] like Figure 4-5 As shown, the present invention also proposes a full-length anchor fixing point yielding support anchor rod based on a full-length anchor fixing point yielding support method for a tunnel, comprising the following steps:

[0042] S1: Determine the location of the separation layer 11 in the upper roof of the tunnel 10 constructed in the coal seam 9. The upper rock layer of the separation layer 11 is defined as the first roof rock layer 7, and the lower rock layer is defined as the second roof rock layer 8;

[0043] S2: Determine the deflection value w1 of the first roof rock layer 7 at the anchor rod installation location, the deflection value w2 of the second roof rock layer 8 at the anchor rod installation location, and the maximum deflection value w3 that the second roof rock layer 8 can withstand at the anchor rod installation location. When the maximum deflection value of the second roof rock layer 8 exceeds w3, the second roof rock layer is damaged.

[0044] The anchor rod can be installed at any position in the width direction of the tunnel 10 according to design requirements ( Figure 4-5 The middle position is shown in the figure), and one or more are set along the width direction according to design requirements;

[0045] If w 2≤ w3, the displacement of the upper rod 4 relative to the lower rod 5 is designed to be no more than w2-w1, which can be w2-w1, or 0.9 times or 0.8 times w2-w1. There is no specific limit here, and it can be determined according to the actual project. The roof rock layer of the tunnel 10 is allowed to be decompressed but not completely decompressed.

[0046] If w 2＞ w3, the displacement of the upper rod 4 relative to the lower rod 5 is designed to be no more than w3-w1, which can be w3-w1, or 0.9 times or 0.8 times w3-w1. There is no specific limitation here, and it can be determined according to the actual project. The roof rock layer of the tunnel 10 is allowed to be decompressed but not completely decompressed.

[0047] Here, the displacement that the upper rod 4 can generate relative to the lower rod 5 refers to the distance that the first connector 42 can move relative to the connecting cavity 51 (also the distance that the second connector 52 can move relative to the connecting groove 41);

[0048] S3: Determine the length of the portion of the lower rod 4 excluding the connection groove 41 and the first connection head 42 , which is slightly longer than the length of the second roof rock layer 8 . The portion exceeding the second roof rock layer 8 serves as the external anchor end for installing the pad 3 and the nut 2 .

[0049] Determine the length of the upper rod 5, which can ensure the support effect of the entire anchor rod, so that it can withstand the downward tension applied to the anchor rod by the second roof rock layer 8, and ensure that the anchor rod does not fail;

[0050] S4: As Figure 4 As shown, after the construction of the roadway 10, the anchor rods are directly installed at the designed position of the roadway 10 roof using an anchor drilling rig, and the upper rod body 5 is completely and only located in the first roof rock layer 7, and the lower rod body 4 is only located in the second roof rock layer 8. The part exposed from the second roof rock layer 8 is sleeved with the backing plate 3 and then fixed with the nut 2;

[0051] The anchor drilling rig rotates the anchor in a direction such that the anchor can be screwed into the tunnel roof rock through its peripheral thread, and this rotation direction causes the lower rod body 4 and the upper rod body 5 to be in a similar motion, that is, the connecting groove 41 and the first connecting head 42 are completely located in the accommodating cavity;

[0052] S5: If Figure 5 As shown, later, as time goes by, the second roof rock layer 8 produces separation 11 relative to the first roof rock layer 7, and the lower rod body 4 is pulled by the second roof rock layer 8 to produce relative movement with the upper rod body 5, that is, the first connecting head 42 produces relative sliding in the connecting cavity 51; when the relative movement between the lower rod body 4 and the upper rod body 5 reaches the set distance, that is, when the first connecting head 42 slides to the second connecting head 52; the cementitious filling material is injected into the separation layer 11 from the grouting channel 43 through the grouting hole 44. The cementitious filling material can fill the separation layer 11 on the one hand, and can connect the first roof rock layer 7 and the second roof rock layer 8 on the other hand.

[0053] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of methods under the inspiration of the present invention. However, any technical solution that is the same or similar to that of the present application falls within the scope of protection of the present invention.

Claims

1. A full-length anchor fixed point pressure-yielding tunnel support method, using a full-length anchor fixed point pressure-yielding support anchor rod, comprising a lower rod body and an upper rod body of the same outer diameter, wherein the lower rod body and the upper rod body are provided with continuous threads with the same rotation direction on their outer peripheries; The outer diameter of the upper end of the lower rod body is reduced to form a connecting groove, and a first connector is provided at the upper end of the connecting groove, and the outer diameter of the first connector is larger than the outer diameter of the connecting groove and smaller than the outer diameter of the lower rod body; a grouting channel is provided inside the lower rod body, and a grouting hole is provided in the connecting groove, and the grouting hole is connected to the grouting channel; The lower end of the upper rod body is hollow to form a receiving cavity that can accommodate the connecting groove and the first connecting head. The inner diameter of the lower end of the receiving cavity is reduced to form the second connecting head, and the remaining part forms a connecting cavity. The connecting cavity is threadedly connected to the first connecting head. When the anchor rod is screwed in, the threaded connection between the connecting cavity and the first connecting head causes the lower rod body and the upper rod body to move in similar directions. It is characterized in that The steps include: S1: Determine the location of the separation layer in the upper roof of the tunnel, where the upper rock layer of the separation layer is defined as the first roof rock layer, and the lower rock layer is defined as the second roof rock layer; S2: Design the required displacement of the upper rod relative to the lower rod based on the delamination at the anchor bolt installation location; S3: Determine that the length of the lower rod is slightly greater than the length of the second roof rock layer; S4: After the tunnel is constructed, the anchor bolt is directly rotated and drilled into the designed position of the tunnel roof, and the upper rod body is completely and only located in the first roof rock layer, and the lower rod body is only located in the second roof rock layer. The part exposed in the second roof rock layer is sleeved with a backing plate and then tightened with a nut; S5: When the second roof rock layer is separated from the first roof rock layer, a filling material is injected into the separation layer from the grouting channel through the grouting hole.

2. The full-length anchor fixed point pressure-yielding tunnel support method according to claim 1 is characterized in that: The grouting channel extends from the lower end of the lower rod body at least to the connecting groove.

3. The full-length anchor fixed point pressure-yielding tunnel support method according to claim 1 or 2, characterized in that: A grouting plug is provided at the lower end of the grouting channel, a nut and a pad are provided at the outer periphery of the lower portion of the lower rod body, and the nut is threadedly connected to the outer periphery of the lower rod body.

4. The full-length anchor fixed point pressure-yielding tunnel support method according to claim 1 is characterized in that: The second connecting head is threadedly connected to the connecting groove, and the threaded connection between the connecting cavity and the first connecting head and the threaded connection between the second connecting head and the connecting groove can enable the lower rod body and the upper rod body to move toward and away from each other in a certain amount.

5. The full-length anchor fixed point pressure-yielding tunnel support method according to claim 1 is characterized in that: The second connecting head can move to the lowermost end of the connecting groove.

6. The full-length anchor fixed point pressure-yielding tunnel support method according to claim 1 is characterized in that: A drill bit is detachably or integrally formed on the top end of the upper rod body, and the outer diameter of the drill bit is no greater than the outer diameter of the upper rod body.

7. The full-length anchor fixed point pressure-yielding tunnel support method according to claim 1 is characterized in that: In step S2, the deflection value w1 of the first roof rock layer, the deflection value w2 of the second roof rock layer, and the maximum deflection value w3 that the second roof rock layer can withstand at the anchor bolt installation position are determined; if w 2≤ w3, then the displacement of the upper rod on the lower rod should not exceed w2-w1; if w 2＞ w3, then the displacement of the upper rod relative to the lower rod is designed not to exceed w3-w1.

8. The full-length anchor fixed point pressure-yielding tunnel support method according to claim 1 is characterized in that: In step S2, one or more anchor rods are arranged along the width direction of the tunnel according to the design.

9. The full-length anchor fixed point pressure-yielding tunnel support method according to claim 1 is characterized in that: In step S5, a cementitious filling material is injected.

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