A through-type anchor rod support system for a cattle nose lane and a supporting method thereof

Abstract

The application discloses a through-type anchor rod supporting system for a cow nose roadway and a supporting method thereof, and aims at the problem that a middle column wall in the cow nose roadway is discontinuous in stress and prone to local instability, the application proposes that a plurality of hollow grouting anchor rods are arranged horizontally and penetratingly along the thickness direction of the middle column wall, and the two ends of the anchor rods extend to the spaces of the two side roadways; a tray, a fastening nut and a connecting component interface are installed at the ends, and the ends of the upper and lower adjacent anchor rods are rigidly connected through long straight connecting rods to form a spatial truss type connecting network; and a grouting and reinforcing assembly is used for grouting into the hollow cavities of the anchor rods and the surrounding rock cracks to form a grouting and reinforcing area. Finally, the through-type grouting anchor rod, the spatial connecting assembly and the reinforced middle column wall jointly form a spatial closed whole cooperative bearing structure. The application changes the traditional point-like isolated anchoring into three-dimensional spatial net-like bearing, actively pre-tightens and transmits stress to deep surrounding rock, effectively inhibits early deformation and damage of the surrounding rock, is convenient to construct and is economical and practical.

Description

Technical Field

[0001] This invention relates to the field of mine roadway support technology, specifically a through-type anchor bolt support system and its support method for bull-nose roadways. Background Technology

[0002] During the excavation of underground mine roadways, numerous "bullneck" roadway intersections (i.e., structures resembling a bull's nose at the bifurcation point) are present, and these are typical stress concentration areas. This area typically consists of a complex mechanical stress system formed by the central pillar wall, roof, and surrounding rock of the two wing roadways. Current technologies commonly employ high-strength prestressed anchor bolts (cables), grouting reinforcement, U-shaped steel telescopic supports, or concrete walls for support.

[0003] However, engineering practice shows that even with conventional high-standard support, the following instability characteristics are still commonly observed at the bullnose intersection after excavation: rapid development of cracks in the intermediate column wall, spalling, roof subsidence, and intensified convergence of the two sides, even leading to anchor (cable) tray failure and breakage, among other support component damage. Analysis reveals the following main defects and shortcomings in existing technologies:

[0004] First, the anchoring foundation is weak: when traditional anchor rods (cables) are installed in soft and broken surrounding rock, their anchoring force is significantly reduced, making it difficult to form an effective suspension or compression reinforcement effect.

[0005] Second, the passive support effect is poor: U-shaped steel supports are completely passive supports, which cannot actively suppress early deformation of the surrounding rock, and have a large steel consumption, low degree of mechanization in erection, and high cost.

[0006] Third, rigid structures have poor adaptability: Although concrete walls are rigid, the construction process is complex, the curing period is long, and the initial and later costs are high. They also lack adaptability to the deformation of the surrounding rock and are prone to cracking and failure due to local stress concentration.

[0007] Fourth, the stress system is discontinuous: existing anchors (cables) are mostly arranged as independent points, lacking spatial mechanical connections between components, which makes it impossible to effectively transfer the concentrated stress of the intermediate column wall to the deep stable surrounding rock, causing the column wall to become a weak link in the load-bearing structure.

[0008] Therefore, there is an urgent need for a new type of support system and method that can achieve overall coordinated stress distribution, active deformation control, and is economical and applicable to the intermediate column walls of the bull-nose roadway. Summary of the Invention

[0009] The purpose of this invention is to provide a through-type anchor bolt support system and its support method for bull-nose roadways, so as to solve the problems mentioned in the background art.

[0010] To achieve the above objectives, the present invention provides the following technical solution: a through-type anchor bolt support system for bull-nose roadways, comprising:

[0011] Multiple through-type grouting anchors are horizontally installed along the thickness direction of the intermediate column wall in the bullnose roadway. The grouting anchor is a rod with a hollow inner cavity, and its two ends extend into the roadway space on both sides of the intermediate column wall. Each grouting anchor has a tray and a fastening nut at its end, and a connecting component interface is fixedly installed. Furthermore, each grouting anchor has a grout outlet hole on its outer surface in the middle that connects to the hollow inner cavity.

[0012] The spatial connection component includes multiple long straight connecting rods. The two ends of each long straight connecting rod are rigidly connected to the ends of two adjacent vertically arranged through-hole grouting anchor rods through the interface of the connecting component, forming a spatial truss-type connection network between the upper and lower grouting anchor rods on the side wall of the intermediate column wall.

[0013] The grouting reinforcement component is connected to the anchor hole at the end of the grouting anchor and is used to inject grout into the hollow cavity of the grouting anchor and the surrounding crack zone to form a grouting reinforcement zone.

[0014] The through-type grouting anchor, the spatial connection components, and the grout-reinforced intermediate column wall together constitute a spatially closed, integrated, and collaborative load-bearing structure.

[0015] Preferably, the through-type grouting anchor is a high-strength hollow threaded steel rod with a yield strength of not less than 500 MPa.

[0016] Preferably, the connecting component interface includes a socket, a support ear plate, a support ring, and a threaded sleeve. The socket is sleeved on the outer side of the end of the grouting anchor rod. The support ear plate is fixedly welded to the outer surface of the socket. The support ring is rotatably connected to the inner side of the support ear plate via a shaft. The threaded sleeve is rotatably connected to the inner side of the support ring via a bearing.

[0017] Preferably, both ends of the long straight connecting rod are provided with external threads, which allow for a detachable rigid connection with the threaded sleeve through threaded engagement.

[0018] Preferably, the through-type grouting anchors are arranged in a rectangular or rhomboid grid pattern on the intermediate column wall, and the row spacing and interval are determined according to the surrounding rock conditions.

[0019] A method for through-type anchor bolt support in bull-nose tunnels includes the following steps:

[0020] S1, Drilling: At the designed location of the central pillar wall in the Niubizi alley, drill multiple through holes horizontally along its thickness direction;

[0021] S2, Install grouting anchor and spatial connection components: Insert the through-hole grouting anchor into the borehole, so that its two ends are exposed on both sides of the middle column wall; install the tray, the connection component interface and the fastening nut to initially fix the grouting anchor and the connection component interface; use a long straight connecting rod to rigidly connect the ends of the adjacent grouting anchors through the connection component interface;

[0022] S3, Apply pre-tightening force: Tighten the fastening nuts in sequence according to the design torque using a torque wrench to apply pre-stress to the anchor rod;

[0023] S4, Grouting reinforcement: Grout is injected into the anchor hole of the grouting anchor through the grouting reinforcement component. The grout inside the hollow cavity overflows from the grout outlet to the surrounding rock fissures, forming a grouting reinforcement zone.

[0024] S5, Final setting and monitoring: After the grout has solidified, the grouting anchor rods, long straight connecting rods and the reinforced intermediate column wall form an integral and collaborative load-bearing structure.

[0025] Preferably, the diameter of the through hole in step S1 matches the diameter of the grouting anchor rod, and high-pressure air is used to remove rock powder from the hole after drilling.

[0026] Preferably, the depth to which the long straight connecting rod is screwed into the threaded sleeve in step S2 is not less than 30 mm.

[0027] Preferably, the grout in step S4 is cement grout or chemical grout, the grouting pressure is controlled at 0.5 to 2.0 MPa, and a pressure-stabilizing grouting method is adopted, with a pressure stabilizing time of not less than 2 minutes.

[0028] Preferably, after the overall collaborative bearing structure described in step S5 is formed, displacement and stress monitoring are carried out on the bull-nose roadway, and the monitoring period is not less than 30 days.

[0029] Beneficial effects

[0030] This invention provides a through-type anchor bolt support system and its support method for bull-nose roadways, which has the following beneficial effects:

[0031] 1. This through-type anchor bolt support system and its support method for "bull nose" roadways, through the combination of grouting anchor bolts and spatial connection components, breaks the isolated force-bearing mode of traditional point anchor bolts, transforming the intermediate column wall into a three-dimensional spatial network load-bearing structure. Grouting further closes the cracks, making the intermediate column wall and the anchoring system an inseparable whole, avoiding successive failures caused by local stress concentration.

[0032] 2. The through-type anchor bolt support system and its support method for the bull-nose roadway, the prestressed active compression of the surrounding rock by the grouting anchor bolt, combined with the immediate filling and cementation of the cracks by grouting, can build a high-strength active support system in the shortest time after excavation, effectively inhibiting the early rheology and delamination of soft and broken surrounding rock, and greatly reducing the amount of maintenance work in the later stage.

[0033] 3. The through-type anchor bolt support system and its support method used in the bull-nose roadway, the long straight connecting rod actively guides and transfers the high stress borne by the intermediate column wall to the deep stable surrounding rock of the two side roadways through the end of the grouting anchor bolt, changing the mechanical path of the column wall bearing the load alone in the traditional technology, and realizing the effective dissipation of stress.

[0034] 4. Compared to U-shaped steel supports and concrete walls, the through-type anchor bolt support system and its support method used in bull-nose roadways offer a higher degree of mechanization, lower material consumption, and lower labor intensity. Furthermore, it exhibits good adaptability to soft and fractured surrounding rock, effectively reducing rework rates and safety risks, resulting in significant overall economic benefits. Attached Figure Description

[0035] Figure 1 This is a cross-sectional schematic diagram of the intermediate column wall of a through-type anchor bolt support system and its support method for a bull-nose tunnel proposed in this invention.

[0036] Figure 2 This is a schematic diagram of the distribution of grouting anchor bolts on the surface of the intermediate column wall in a through-type anchor bolt support system and support method for bull-nose tunnels proposed in this invention.

[0037] Figure 3 This is a schematic diagram of the spatial connection component structure of a through-type anchor bolt support system and its support method for bull-nose tunnels proposed in this invention.

[0038] Figure 4 This is a three-dimensional structural diagram of a grouting anchor bolt for a through-type anchor bolt support system and support method for a bull-nose roadway proposed in this invention.

[0039] Figure 5 This is a schematic cross-sectional view of the grouting anchor bolt structure of a through-type anchor bolt support system and support method for bull-nose roadways proposed in this invention.

[0040] Figure 6 This is a three-dimensional structural diagram of the interface of the connecting components of a through-type anchor bolt support system and its support method for bullnose roadways proposed in this invention.

[0041] In the diagram: 1. Grouting anchor; 2. Intermediate column wall; 3. Hollow inner cavity; 4. Tray; 5. Fastening nut; 6. Connecting component interface; 7. Grout outlet hole; 8. Long straight connecting rod; 9. Grouting reinforcement area; 10. Sleeve seat; 11. Support ear plate; 12. Support ring; 13. Threaded sleeve. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0044] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0045] Please see Figures 1 to 6 The present invention provides a technical solution: a through-type anchor bolt support system for bull-nose roadways, comprising multiple through-type grouting anchor bolts 1, a spatial connection component and a grouting reinforcement component.

[0046] Multiple through-type grouting anchor rods 1 are horizontally installed along the thickness direction of the intermediate pillar wall 2 in the "bull's nose" tunnel. Each grouting anchor rod 1 is a rod with a hollow inner cavity 3, extending at both ends into the tunnel space on either side of the intermediate pillar wall 2. Each grouting anchor rod 1 has a tray 4 and a fastening nut 5 at its end, and a connecting component interface 6 is fixedly installed thereon. A grout outlet hole 7, communicating with the hollow inner cavity 3, is opened on the outer surface of the middle section of each grouting anchor rod 1. In this embodiment, the diameter of the grouting anchor rod 1 is 25 mm, and the number of grout outlet holes 7 is three, arranged in a ring array.

[0047] The spatial connection assembly includes multiple long straight connecting rods 8, which are made of round steel or threaded steel with a diameter of 20mm. The two ends of each long straight connecting rod 8 are rigidly connected to the ends of two adjacent vertically arranged through-hole grouting anchor rods 1 through the connecting component interface 6, forming a spatial truss-type connection network between the upper and lower grouting anchor rods 1 on the side wall of the intermediate column wall 2.

[0048] The grouting reinforcement component is connected to the anchor hole at the end of the grouting anchor 1, and is used to inject grout into the hollow inner cavity 3 of the grouting anchor and the surrounding crack zone to form the grouting reinforcement zone 9. In this embodiment, the grout is ordinary Portland cement grout with a water-cement ratio of 0.8:1.

[0049] After grouting is completed, the wall is left to cure for 24 hours. Once the grout has fully set, the original cracks in the intermediate column wall 2 and the annular gaps around the boreholes are fully filled by the grouting reinforcement zone 9, forming a dense solid. Ultimately, the through-type grouting anchor 1, the spatial connection components, and the grouting-reinforced intermediate column wall 2 together constitute a spatially closed, integrated, and collaborative load-bearing structure.

[0050] As a preferred option, the through-type grouting anchor rod 1 is a high-strength hollow threaded steel rod with a yield strength of not less than 500MPa.

[0051] Please see Figures 2 to 6 The connecting component interface 6 includes a socket 10, a support ear plate 11, a support ring 12, and a threaded sleeve 13. The socket 10 is sleeved on the outer side of the end of the grouting anchor rod 1. The support ear plate 11 is fixedly welded to the outer surface of the socket 10. The support ring 12 is rotatably connected to the inner side of the support ear plate 11 via a shaft. The threaded sleeve 13 is rotatably connected to the inner side of the support ring 12 via a bearing. By tightening the fastening nut 5, the socket 10 and the tray 4 are secured, thus fixing the connecting component interface 6 and the tray 4. By rotating the support ring 12, the orientation of the threaded sleeve 13 can be adjusted, thus facilitating the installation of the long straight connecting rod 8 with a certain inclination. The outer side of the threaded sleeve 13 has a hexagonal design, so the threaded sleeve 13 can be rotated with a wrench to facilitate the threaded connection between the long straight connecting rod 8 and the threaded sleeve 13.

[0052] The long straight connecting rod 8 has external threads at both ends, and is rigidly connected to the threaded sleeve 13 in a detachable manner through threaded engagement.

[0053] The through-type grouting anchor bolts 1 are arranged in a rectangular or rhomboid grid pattern on the intermediate column wall 2. The row spacing and interval are determined according to the surrounding rock conditions, as shown in the figure below. Figure 1 and Figure 2 As shown.

[0054] The present invention also provides a method for through-type anchor bolt support in bull-nose roadways, employing the above-mentioned system and including the following steps:

[0055] S1, Drilling: At the designed location of the central pillar wall 2 in the Niubizi tunnel, drill multiple through holes horizontally along its thickness direction. An anchor drilling rig can be used for this purpose. The diameter of the through holes matches the diameter of the grouting anchor 1. After drilling, high-pressure air is used to remove rock powder from the holes.

[0056] S2, Install the grouting anchor and spatial connection assembly: Insert the through-type grouting anchor 1 into the drilled hole, ensuring both ends protrude from both sides of the intermediate column wall 2; install the tray 4, the connecting component interface 6, and the fastening nut 5 to initially fix the grouting anchor 1 and the connecting component interface 6; use the long straight connecting rod 8 to rigidly connect the ends of adjacent grouting anchors 1 through the connecting component interface 6. The long straight connecting rod 8 should be screwed into the threaded sleeve 13 to a depth of not less than 30mm.

[0057] S3, Apply prestress: Tighten the fastening nuts 5 sequentially using a torque wrench according to the design torque to apply prestress to the grouting anchor rod 1. The design torque is set to 80-150 Nm based on the surrounding rock conditions. .

[0058] S4, Grouting Reinforcement: Grout is injected into the anchor hole of the grouting anchor 1 through the grouting reinforcement component. The grout inside the hollow inner cavity 3 overflows from the grout outlet 7 into the surrounding rock fissures, forming the grouting reinforcement zone 9. The grout is cement grout or chemical grout, the grouting pressure is controlled between 0.5 and 2.0 MPa, and a pressure-stabilized grouting method is adopted, with a pressure stabilization time of not less than 2 minutes.

[0059] S5, Final Setting and Monitoring: After the grout has solidified, the grouting anchor 1, the long straight connecting rod 8, and the reinforced intermediate column wall 2 form an integrated and cooperative load-bearing structure. After the integrated and cooperative load-bearing structure is formed, displacement and stress monitoring are carried out on the "bull nose" roadway, with a monitoring cycle of no less than 30 days.

[0060] Effect verification:

[0061] During the subsequent tunnel excavation and mining period, long-term monitoring was conducted on the intersection of the "bull nose" tunnels using the support scheme of this embodiment. The results showed that:

[0062] The surface displacement of the intermediate column wall 2 is controlled within 15mm, which is much lower than the 60-100mm of traditional support.

[0063] The grouting anchor 1 was stable under stress, and there was no obvious deformation of the tray 4 or breakage of the grouting anchor 1.

[0064] No new through cracks or spalling appeared on the surface of the intermediate column wall 2, and the tunnel cross-section was well formed, requiring no repair.

[0065] In summary, this invention successfully solves the long-standing instability problem in the "bull-nose" roadway by integrating "through-type grouting anchor bolts, spatial rigid connection, active pre-tightening, and crack grouting," and has high practical value and promising prospects for promotion.

[0066] The accompanying drawings of the embodiments disclosed in this invention only involve the structures involved in the embodiments of this disclosure. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this invention can be combined with each other.

[0067] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A through-type anchor bolt support system for bull-nose roadways, characterized in that, include: Multiple through-type grouting anchor rods (1) are horizontally installed along the thickness direction of the middle column wall (2) of the bullnose roadway. The grouting anchor rod (1) is a rod with a hollow inner cavity (3) inside, and its two ends extend into the roadway space on both sides of the middle column wall (2). Each grouting anchor rod (1) is provided with a tray (4) and a fastening nut (5) at its end, and is fixedly installed with a connecting component interface (6). Furthermore, each grouting anchor rod (1) has a grout outlet hole (7) that connects to the hollow inner cavity (3) on its middle outer surface. The spatial connection component includes multiple long straight connecting rods (8). The two ends of each long straight connecting rod (8) are rigidly connected to the ends of two adjacent vertically arranged through-hole grouting anchor rods (1) through the connection component interface (6), forming a spatial truss connection network between the upper and lower grouting anchor rods (1) on the side wall of the intermediate column wall (2). The grouting reinforcement component is connected to the anchor hole at the end of the grouting anchor (1) and is used to inject grout into the hollow inner cavity (3) and surrounding crack zone of the grouting anchor (1) to form a grouting reinforcement zone (9). The through-type grouting anchor (1), the spatial connection component, and the intermediate column wall (2) reinforced by grouting together constitute a spatially closed overall collaborative load-bearing structure.

2. The through-type anchor bolt support system for bullnose roadways according to claim 1, characterized in that: The through-type grouting anchor (1) is a high-strength hollow threaded steel rod with a yield strength of not less than 500MPa.

3. The through-type anchor bolt support system for bull-nose tunnels according to claim 1, characterized in that: The connecting component interface (6) includes a socket (10), a support ear plate (11), a support ring (12), and a threaded sleeve (13). The socket (10) is sleeved on the outer side of the end of the grouting anchor rod (1). The support ear plate (11) is fixedly welded to the outer surface of the socket (10). The support ring (12) is rotatably connected to the inner side of the support ear plate (11) through a shaft. The threaded sleeve (13) is rotatably connected to the inner side of the support ring (12) through a bearing.

4. A through-type anchor bolt support system for bullnose roadways according to claim 3, characterized in that: The long straight connecting rod (8) has external threads at both ends, and is rigidly connected to the threaded sleeve (13) in a detachable manner through threaded engagement.

5. A through-type anchor bolt support system for bull-nose roadways according to claim 1, characterized in that: The through-type grouting anchors (1) are arranged in a rectangular or rhomboid grid on the intermediate column wall (2), and the row spacing and spacing are determined according to the surrounding rock conditions.

6. A method for through-bolt support of a bull-nose roadway using the through-bolt support system according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1, Drilling: At the designed position of the middle column wall (2) in the Niubizi alley, drill multiple through holes horizontally along its thickness direction; S2, Install the grouting anchor (1) and the spatial connection component: Insert the through grouting anchor (1) into the drill hole so that both ends of it are exposed on both sides of the middle column wall (2); Install the tray (4), the connecting component interface (6) and the fastening nut (5) to initially fix the grouting anchor (1) and the connecting component interface (6); Use the long straight connecting rod (8) to rigidly connect the ends of the upper and lower adjacent grouting anchors (1) through the connecting component interface (6); S3, apply pre-tightening force: tighten the fastening nuts (5) in sequence with a torque wrench according to the design torque to apply pre-stress to the grouting anchor (1); S4, Grouting reinforcement: Grout is injected into the anchor hole of the grouting anchor (1) through the grouting reinforcement component. The grout inside the hollow cavity (3) overflows from the grout outlet (7) to the surrounding rock fissures, forming the grouting reinforcement zone (9). S5, Final setting and monitoring: After the grout has solidified, the grouting anchor (1), the long straight connecting rod (8) and the reinforced intermediate column wall (2) form an integral and coordinated load-bearing structure.

7. The method for through-type anchor bolt support for bull-nose roadways according to claim 6, characterized in that, In step S1, the diameter of the through hole is matched with the diameter of the grouting anchor rod (1), and high-pressure air is used to remove the rock powder inside the through hole after drilling.

8. The method for through-type anchor bolt support for bull-nose roadways according to claim 6, characterized in that, The depth to which the long straight connecting rod (8) described in step S2 is screwed into the threaded sleeve (13) is not less than 30 mm.

9. The method for through-type anchor bolt support for bull-nose roadways according to claim 6, characterized in that, The grout in step S4 is cement grout or chemical grout, the grouting pressure is controlled between 0.5 and 2.0 MPa, and a pressure-stabilizing grouting method is adopted, with a stabilizing time of not less than 2 minutes.

10. The method for through-type anchor bolt support for bull-nose roadways according to claim 6, characterized in that, After the overall collaborative bearing structure described in step S5 is formed, displacement and stress monitoring shall be carried out on the bull-nose roadway, and the monitoring period shall not be less than 30 days.

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