Drill-anchor-grouting integrated segmented self-drilling hollow grouting anchor cable system and construction method thereof

Abstract

A kind of drilling and anchoring integrated segmented self-drilling hollow grouting anchor cable system and its construction method belong to coal mine roadway supporting technical field, system: end, middle and head end rigid-flexible composite unit are connected in proper order;End, middle and head end rigid-flexible composite unit all include by inside to outside sequentially fixedly connected grouting pipe, flexible anchor cable section and rigid sleeve;The first and last ends of middle grouting pipe are fixedly connected with the end of head end grouting pipe and the first end of end grouting pipe respectively;The first and last ends of middle rigid sleeve are fixedly connected with the end of head end rigid sleeve and the first end of end rigid sleeve respectively, at least one grout outlet is arranged in the first end of middle rigid sleeve;Reamer is coaxially fixedly installed in the first end of head end rigid sleeve.The method: using segmented drilling, operation mode of connecting section by section, in the process of drilling, make rigid sleeve follow up with drill bit and support hole wall in real time, after drilling, grouting operation is carried out and pre-tightening force is applied.The present application can improve the stability and reliability of surrounding rock support.

Description

Technical Field

[0001] This invention belongs to the field of coal mine roadway support technology, specifically relating to a segmented self-drilling hollow grouting anchor cable system integrating drilling, anchoring and grouting and its construction method. Background Technology

[0002] In the field of coal mine roadway support technology, anchor cable support technology has become one of the core technical means for controlling surrounding rock under complex geological conditions due to its significant advantages such as large anchoring depth, high bearing capacity, and good active support effect. As coal mine construction continues to extend deeper, adverse geological conditions such as loose and fractured surrounding rock, soft rock, and fault fracture zones are becoming increasingly common, posing severe challenges to anchor cable construction. Traditional anchor cable construction requires drilling holes before installing anchor cables. However, after drilling, the borehole wall is prone to collapse, which not only prevents the anchor cables from being installed properly but may also result in abandoned holes, affecting construction efficiency and subsequent support quality. Simultaneously, the surrounding rock in deep roadways has large deformation and a wide fracture range, requiring grouting to cement and reinforce the fractured surrounding rock to effectively improve its bearing capacity. Reliable filling of the annular gap between the anchor cable and the borehole is also necessary to achieve coordinated bearing between the anchor cable and the surrounding rock, thereby ensuring the stability of the support. To solve these construction problems, integrated drilling, anchoring, and grouting technology has emerged. This technology integrates drilling, anchoring, and grouting into a single process, simultaneously installing anchor bolts and grouting during drilling. This effectively addresses working conditions in collapsed formations, significantly improving construction efficiency and support effectiveness. However, existing integrated drilling-anchoring-grouting technology is primarily applied to anchor bolts. Most existing integrated anchor bolts utilize hollow threaded steel rods, which, while capable of self-drilling, are limited by the rigidity of the rod, hindering long-distance bending and transportation, severely restricting their application in confined downhole conditions. Compared to anchor bolts, anchor cables offer significant advantages such as flexibility, ease of transport, and continuous extension, making them more suitable for the demands of confined downhole spaces and long-distance transportation. However, due to their flexible structure, they cannot directly transmit the rotational torque and axial thrust required for drilling. This core technological bottleneck has resulted in a long-standing lack of research and development in integrated drilling-anchoring-grouting anchor cables.

[0003] In recent years, while there have been sporadic explorations in research on anchor cable self-drilling technology, overall progress has been slow, with few mature engineering applications. Some studies have attempted to achieve variable stiffness characteristics of anchor cables under stress through material innovation, such as using negative Poisson's ratio materials or smart materials to increase the stiffness of the anchor cable under stress and meet the power transmission requirements of drilling. However, the preparation process of such materials is complex and costly, and the response speed and control precision of variable stiffness under stress are difficult to match the real-time requirements of drilling conditions. Currently, these studies remain in the laboratory research stage and cannot be commercialized. Other studies have attempted to add auxiliary drilling devices to the outside of the anchor cable to compensate for its inability to transmit power. However, existing auxiliary devices generally suffer from complex structures and cumbersome operations, making them unsuitable for the confined working space downhole, resulting in poor practicality and hindering large-scale application.

[0004] Fundamentally, the core challenge in achieving self-drilling functionality with flexible anchor cables lies in the fact that, during drilling, the anchor cable must simultaneously possess both contradictory properties of flexibility and rigidity. The portion outside the borehole must remain flexible to meet the requirements of coiling, transport, and continuous extension, while the portion inside the borehole must become rigid to stably transmit the rotational torque and axial thrust required for drilling. Current technology has yet to find an engineering solution that balances both characteristics while also being economical and reliable, resulting in a long-standing technological gap in integrated drilling-anchor-grouting anchor cables, failing to meet the actual needs of deep coal mine roadway support under adverse geological conditions. To overcome these shortcomings, there is an urgent need for an integrated drilling-anchor-grouting segmented self-drilling hollow grouting anchor cable system and its construction method. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a segmented self-drilling hollow grouting anchor cable system integrating drilling, anchoring, and grouting, and its construction method. This system features a simple structure, low manufacturing cost, convenient construction process, easy transportation and extension, and strong adaptability. It enables integrated drilling, anchoring, and grouting operations in loose and fractured rock strata, while simultaneously achieving immediate support and full-length anchoring, effectively ensuring the stability and reliability of the surrounding rock support. This method offers high construction efficiency and ideal anchoring effect, enabling integrated drilling, anchoring, and grouting construction and reliable support for soft surrounding rock, thus improving the stability of the surrounding rock support.

[0006] To achieve the above objectives, the present invention provides a segmented self-drilling hollow grouting anchor cable system integrating drilling, anchoring and grouting, comprising a rigid-flexible composite, a locking device, a tray and a reaming drill bit;

[0007] The rigid-flexible composite structure comprises, along the axial direction, an end rigid-flexible composite unit, a middle rigid-flexible composite unit, and a beginning rigid-flexible composite unit. The end rigid-flexible composite unit comprises, from the inside out, an end grouting pipe, an end flexible anchor cable segment, and an end rigid sleeve, all fixedly connected in sequence. The middle rigid-flexible composite unit comprises, from the inside out, a middle grouting pipe, a middle flexible anchor cable segment, and a middle rigid sleeve, all fixedly connected in sequence. The beginning rigid-flexible composite unit comprises, from the inside out, a beginning grouting pipe, a beginning flexible anchor cable segment, and a beginning rigid sleeve, all fixedly connected in sequence. The beginning and end ends of the middle grouting pipe are fixedly connected to the end of the beginning grouting pipe and the beginning of the end grouting pipe, respectively. The beginning and end ends of the middle rigid sleeve are fixedly connected to the end of the beginning rigid sleeve and the beginning of the end rigid sleeve, respectively. The beginning end of the beginning rigid sleeve has at least one grout outlet.

[0008] The reaming drill bit is coaxially and fixedly installed at the beginning end of the rigid sleeve.

[0009] The lock and the tray are sequentially fitted onto the outside of the end section of the rigid sleeve, and the lock and the end section of the rigid sleeve are engaged by a threaded structure.

[0010] This invention proposes a segmented self-drilling anchor system with rigid-flexible separation and functional synergy. It innovatively decomposes the overall anchor system into multiple rigid-flexible composite units. Each composite unit is designed as a composite structure consisting of an outer rigid sleeve, an inner flexible anchor cable, and a central grouting pipe. After the rigid-flexible composite units at the end, middle, and beginning are cascaded, the entire length of the internal flexible anchor cable is protected by the outer rigid sleeve, forming a complete support structure with an outer rigidity and an inner flexibility. Furthermore, by installing a reaming drill bit at the beginning of the first-end rigid-flexible composite unit, the rigid-inner-flexible anchor system simultaneously acquires autonomous drilling capabilities. In this way, during drilling, each section of the outer rigid casing can serve as a reliable force transmission component and remain along its entire length, achieving the dual functions of effective transmission of drilling force and reliable support of the borehole wall. Simultaneously, the inner flexible anchor cable serves as a support structure for the grouting pipe and a prestressing structure. This segmented composite structure solves the technical problem of flexible anchor cables being unable to transmit drilling force. It also addresses key technical challenges such as borehole collapse, difficulty in hole formation, and the complex stress distribution of traditional self-drilling anchors in long-distance drilling in loose and fractured strata. Therefore, this invention creatively decouples and recombines the rigid casing used in casing drilling with the prestressed flexible anchor cable, solving the problem of their coordinated operation during drilling, connection, and grouting processes. This forms a novel composite structure and working mode, enabling efficient and reliable integrated drilling, anchoring, and grouting operations in loose and fractured strata.

[0011] The system has a simple structure, low manufacturing cost, convenient construction process, easy transportation and extension, and strong adaptability. It can realize integrated drilling, anchoring and injection construction of loose and broken rock layers. At the same time, it can achieve immediate support and full-length anchoring, which can improve the stability and reliability of surrounding rock support. It can be widely used in mining roadways, tunnel engineering and slope treatment.

[0012] Furthermore, in order to facilitate rapid assembly between the end rigid-flexible composite unit, the middle rigid-flexible composite unit, and the head rigid-flexible composite unit, and to ensure the connection strength and reliability between the rigid-flexible composite units, the outer side of the end of the end rigid sleeve is provided with an external thread locking section that cooperates with the lock, and the inner side of its head end has an internal thread connection section; the outer side of the head end of the end grouting pipe has an end insertion section.

[0013] The outer side of the end of the central rigid sleeve is provided with a central external threaded connection section, and the inner side of its first end is provided with a central internal threaded connection section; the inner side of the end of the central grouting pipe is provided with a central sleeve section, and the outer side of its first end is provided with a central insertion section; the central external threaded connection section is inserted into the inner side of the end internal threaded connection section through threaded engagement; the central sleeve section is sealed and fitted onto the outside of the end insertion section.

[0014] The outer side of the end of the rigid sleeve is provided with an external threaded connection section; the inner side of the end of the grouting pipe is provided with a sleeve section; the external threaded connection section is inserted into the middle internal threaded connection section through threaded engagement; the sleeve section is sealed and fitted onto the outside of the middle insertion section; the grout outlet is opened at the beginning of the rigid sleeve and communicates with the beginning of the grouting pipe through a radial channel opened on the flexible anchor cable section.

[0015] In this technical solution, an external threaded locking section is provided at the end of the rigid sleeve, which facilitates the assembly of the locking device and, consequently, the application of pre-tightening force. An internal threaded connection section is provided at the beginning of the rigid sleeve, and an insertion section is provided at the beginning of the grouting pipe. Simultaneously, a central external threaded connection section is provided at the end of the rigid sleeve, and a central sleeve section is provided at the end of the grouting pipe. This allows for an integrated rigid connection between the rigid-flexible composite unit at the end and the rigid-flexible composite unit at the middle, based on the threaded connection between the internal and external threaded connection sections. Furthermore, the insertion connection between the insertion section and the central sleeve section establishes effective communication between the internal grouting channels of the rigid-flexible composite unit at the end and the middle. A central internal threaded connection section is set at the first end of the central rigid sleeve, and a central insertion section is set at the first end of the central grouting pipe. At the same time, a central external threaded connection section is set at the end of the central rigid sleeve, and a central sleeve section is set at the end of the central grouting pipe. Based on the threaded connection of the central internal threaded connection section and the central external threaded connection section, an integrated rigid connection between the central rigid-flexible composite unit and the central rigid-flexible composite unit can be achieved. Furthermore, based on the insertion connection between the central insertion section and the central sleeve section, an effective connection can be established between the internal grouting channels of the central rigid-flexible composite unit and the central rigid-flexible composite unit.

[0016] Furthermore, in order to form an annular grouting gap between the borehole and the rigid casing, providing an annular flow channel for subsequent grouting, the outer diameters of the end rigid casing, the middle rigid casing, and the beginning rigid casing are equal and all are... The maximum diameter of the reaming drill bit Greater than .

[0017] As a preferred embodiment, the end rigid sleeve, the middle rigid sleeve, and the first rigid sleeve are all made of thick steel pipes, which ensures the support effect; the end grouting pipe, the middle grouting pipe, and the first grouting pipe are all made of thin steel pipes, which ensures the stability of the grouting channel and facilitates the smooth progress of subsequent grouting; the end flexible anchor cable section, the middle flexible anchor cable section, and the first flexible anchor cable section are all made of steel strand with hollow channels, which effectively ensures the reliable application of preload.

[0018] As a preferred embodiment, the first and last ends of the end rigid sleeve are respectively fixedly connected by two end compression anchor sleeves and the first and last ends of the end flexible anchor cable segment; the first and last ends of the middle rigid sleeve are respectively fixedly connected by two middle compression anchor sleeves and the first and last ends of the middle flexible anchor cable segment; and the first and last ends of the first end rigid sleeve are respectively fixedly connected by two first end compression anchor sleeves and the first and last ends of the first end flexible anchor cable segment.

[0019] In this technical solution, the rigid casing and the flexible anchor cable are fixedly connected by compression anchoring, enabling the flexible anchor cable segment to withstand axial tensile force. This allows for the effective application of preload to each rigid-flexible composite unit, achieving active support. Furthermore, by incorporating mature technologies such as threaded connections between adjacent rigid-flexible composite units, the solution is easier to manufacture and assemble on-site. It also facilitates transportation and downhole operations, demonstrating excellent engineering practicality and economic efficiency.

[0020] This invention also provides a construction method for an integrated drilling, anchoring, and grouting segmented self-drilling hollow grouting anchor cable, employing an integrated drilling, anchoring, and grouting segmented self-drilling hollow grouting anchor cable system, comprising the following steps:

[0021] Step 1: Determining the drilling depth and the number of intermediate anchor cable units;

[0022] Based on the engineering geological survey report and on-site detection methods, the design depth of the borehole is determined, and then the number of rigid-flexible composite units in the middle is determined based on the design depth.

[0023] Step 2: Drilling preparation and preliminary construction;

[0024] A reaming drill bit is fixedly installed at the first end of the rigid-flexible composite unit, and the end of the rigid-flexible composite unit is connected to the drilling rig. The drilling rig is started to carry out the first stage of drilling operation. The reaming drill bit cuts the rock and soil to form a borehole, and the rigid casing at the first end is used to support the borehole wall in real time until the external threaded connection section at the first end reaches the borehole opening.

[0025] Step 3: Segmented connection and mid-section construction;

[0026] S31: Connect the middle rigid-flexible composite unit coaxially to the end of the first rigid-flexible composite unit, connect the end of the middle rigid-flexible composite unit to the drilling rig, start the drilling rig to perform the second stage of drilling, and stop when the middle external thread connection section reaches the hole opening.

[0027] S32: Cascade the next intermediate rigid-flexible composite unit at the end of the intermediate rigid-flexible composite unit, connect the end of the next intermediate rigid-flexible composite unit to the drilling rig, start the drilling rig to perform intermediate drilling operations, and stop when the intermediate external thread connection section reaches the borehole.

[0028] S33: Repeat S32 until the middle external thread connection section of the last middle rigid-flexible composite unit reaches the orifice;

[0029] Step 4: Final segment connection and final segment construction;

[0030] At the end of the last central rigid-flexible composite unit, coaxially connect the end rigid-flexible composite unit, connect the end of the end rigid-flexible composite unit to the drilling rig, start the drilling rig to perform the final drilling operation, and stop when the external thread locking section reaches the hole opening.

[0031] Step 5: Grouting operation;

[0032] Grouting anchoring material is injected through the end grouting pipe. The grouting anchoring material flows out through the grout outlet and enters the annular gap between the rigid casing and the borehole. It gradually fills the hole from the bottom to the opening. During the reverse filling process, the grout seeps radially into the surrounding rock fissures under pressure, cementing and reinforcing the broken surrounding rock.

[0033] Step 6: Apply preload;

[0034] After the slurry has cured to the design strength, the tray and lock are sequentially installed on the external thread locking section, and the design preload is applied and locked using tensioning equipment.

[0035] As a preferred option, in step 5, the grouting anchoring material is a cement-based grout or a chemical grout, and the grouting pressure is controlled between 0.5 MPa and 1.5 MPa.

[0036] This invention employs a segmented drilling and segment-by-segment connection method. During drilling, the rigid casing advances with the drill bit and provides real-time support to the borehole wall, offering immediate support to loose and fractured surrounding rock. This effectively prevents borehole collapse in loose and fractured rock strata during drilling. The flexible anchor cable segment applies preload within the rigid casing without directly transmitting rotational torque, leveraging the advantages of active support. Thus, the two functions complement each other and work together to achieve phased functional synergy: the segmented flexible body achieves drilling stiffness transition, the rigid casing ensures borehole formation, the grouting body strengthens anchoring, and prestressed active support is provided. Furthermore, this invention leaves the entire length of the rigid casing within the borehole, becoming part of the permanent support structure. Together with the grouting body, it forms a composite anchor body, greatly improving the reliability of the anchoring.

[0037] This method boasts high construction efficiency and ideal anchoring effect. It solves the problems of flexible anchor cables being unable to self-drill and long anchor cables in weak surrounding rock being prone to hole collapse, ensuring that anchor cables can be successfully installed to the design depth. It also retains the advantages of anchor cables being easy to transport and having good long-distance anchoring effect. At the same time, it realizes integrated construction of drilling, anchoring, and grouting, as well as reliable support for soft surrounding rock, thus improving the stability of surrounding rock support. Attached Figure Description

[0038] Figure 1 This is an assembly diagram of the end-effector rigid-flexible composite unit, lock, and tray in this invention; Figure 2 This is a schematic diagram of the central rigid-flexible composite unit in this invention; Figure 3 This is a schematic diagram of the structure of the rigid-flexible composite unit at the front end in this invention; Figure 4 This is a schematic diagram of the overall structure of the anchor cable system after assembly in this invention; Figure 5 This is a schematic diagram of the assembly of the anchor cable system in the borehole after assembly in this invention; Figure 6 This is a schematic diagram of the anchoring state of the anchor cable system in the borehole after assembly in this invention; Figure 7 This is an assembly diagram of the central rigid-flexible composite unit and the head rigid-flexible composite unit in this invention.

[0039] In the diagram, 1. Reamer bit, 2. Rigid casing at the beginning, 3. Flexible anchor cable section at the beginning, 4. Rigid casing in the middle, 5. Flexible anchor cable section in the middle, 6. Rigid casing at the end, 7. Flexible anchor cable section at the end, 8. Grout outlet, 9. Grouting pipe at the beginning, 10. Insertion section at the end, 11. Grouting pipe at the end, 12. Lock, 13. Tray, 14. Grouting pipe in the middle, 15. Socket section in the middle, 16. Drill hole, 17. Grouting anchoring material, 18. Socket section at the beginning, 19. Internal threaded connection section at the end, 20. Internal threaded connection section in the middle, 21. External threaded connection section in the middle, 22. Insertion section in the middle, 23. External threaded locking section, 24. External threaded connection section at the beginning, 25. Rigid-flexible composite unit at the end, 26. Rigid-flexible composite unit in the middle, 27. Rigid-flexible composite unit at the beginning. Detailed Implementation

[0040] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0041] like Figures 1 to 7 As shown, the present invention provides a segmented self-drilling hollow grouting anchor cable system integrating drilling, anchoring and grouting, including a rigid-flexible composite body, a locking device 12, a tray 13 and a reaming drill bit 1;

[0042] The rigid-flexible composite includes an end rigid-flexible composite unit 25, a middle rigid-flexible composite unit 26, and a beginning rigid-flexible composite unit 27 arranged sequentially along the axial direction. The end rigid-flexible composite unit 25 includes an end grouting pipe 11, an end flexible anchor cable section 7, and an end rigid sleeve 6, which are fixedly connected sequentially from the inside to the outside. The middle rigid-flexible composite unit 26 includes a middle grouting pipe 14, a middle flexible anchor cable section 5, and a middle rigid sleeve 4, which are fixedly connected sequentially from the inside to the outside. The beginning rigid-flexible composite unit 27 includes a beginning grouting pipe 9, a beginning flexible anchor cable section 3, and a beginning rigid sleeve 2, which are fixedly connected sequentially from the inside to the outside. The beginning and end ends of the middle grouting pipe 14 are fixedly connected to the end of the beginning grouting pipe 9 and the beginning of the end grouting pipe 11, respectively. The beginning and end ends of the middle rigid sleeve 4 are fixedly connected to the end of the beginning rigid sleeve 2 and the beginning of the end rigid sleeve 6, respectively. The beginning end of the beginning rigid sleeve 2 has at least one grout outlet 8.

[0043] The reaming drill bit 1 is coaxially and fixedly installed at the beginning end of the rigid sleeve 2;

[0044] The lock 12 and the tray 13 are sequentially fitted onto the outer side of the end rigid sleeve 6, and the lock 12 and the end rigid sleeve 6 are engaged by a threaded structure.

[0045] To facilitate rapid assembly between the end rigid-flexible composite unit, the middle rigid-flexible composite unit, and the head rigid-flexible composite unit, and to ensure the connection strength and reliability between the rigid-flexible composite units, the outer side of the end rigid sleeve 6 is provided with an external threaded locking section 23 that mates with the lock 12, and the inner side of its head end has an internal threaded connection section 19 on the right side of the head end of the end flexible anchor cable section 7; the outer side of the head end of the end grouting pipe 11 has an end insertion section 10 inside the internal threaded connection section 19. Preferably, the head end of the end insertion section 10 is located on the right side of the head end of the internal threaded connection section 19 to facilitate rapid insertion connection.

[0046] The outer side of the end of the central rigid casing 4 is provided with a central external threaded connection section 21, and the inner side of its first end is provided with a central internal threaded connection section 20 to the right of the first end of the central flexible anchor cable section 5; the inner side of the end of the central grouting pipe 14 is provided with a central sleeve section 15, and the outer side of its first end is provided with a central insertion section 22 inside the central internal threaded connection section 20; as a preferred embodiment, the first end of the central insertion section 22 is located to the right of the first end of the central internal threaded connection section 20 to facilitate quick insertion connection; the central external threaded connection section 21 is inserted into the inner side of the end internal threaded connection section 19 through threaded engagement; the central sleeve section 15 is sealed and fitted onto the outer side of the end insertion section 10 to achieve a fixed connection between the central rigid-flexible composite unit 26 and the end rigid-flexible composite unit 25, thereby effectively transmitting the rotational torque and axial thrust during the drilling process;

[0047] The outer side of the end of the rigid casing 2 is provided with an external threaded connection section 24; the inner side of the end of the grouting pipe 9 is provided with an end sleeve section 18; the external threaded connection section 24 is inserted into the middle internal threaded connection section 20 through threaded engagement; the end sleeve section 18 is sealed and fitted onto the outside of the middle insertion section 22 to achieve a fixed connection between the rigid-flexible composite unit 27 and the rigid-flexible composite unit 26, thereby effectively transmitting the rotational torque and axial thrust during drilling; the grout outlet 8 is opened at the beginning of the rigid casing 2 and is connected to the beginning of the grouting pipe 9 through a radial channel opened on the flexible anchor section 3.

[0048] In this technical solution, an external threaded locking section is provided at the end of the rigid sleeve, which facilitates the assembly of the locking device and, consequently, the application of pre-tightening force. An internal threaded connection section is provided at the beginning of the rigid sleeve, and an insertion section is provided at the beginning of the grouting pipe. Simultaneously, a central external threaded connection section is provided at the end of the rigid sleeve, and a central sleeve section is provided at the end of the grouting pipe. This allows for an integrated rigid connection between the rigid-flexible composite unit at the end and the rigid-flexible composite unit at the middle, based on the threaded connection between the internal and external threaded connection sections. Furthermore, the insertion connection between the insertion section and the central sleeve section establishes effective communication between the internal grouting channels of the rigid-flexible composite unit at the end and the middle. A central internal threaded connection section is set at the first end of the central rigid sleeve, and a central insertion section is set at the first end of the central grouting pipe. At the same time, a central external threaded connection section is set at the end of the central rigid sleeve, and a central sleeve section is set at the end of the central grouting pipe. Based on the threaded connection of the central internal threaded connection section and the central external threaded connection section, an integrated rigid connection between the central rigid-flexible composite unit and the central rigid-flexible composite unit can be achieved. Furthermore, based on the insertion connection between the central insertion section and the central sleeve section, an effective connection can be established between the internal grouting channels of the central rigid-flexible composite unit and the central rigid-flexible composite unit.

[0049] Preferably, the number of the middle rigid-flexible composite unit 26 is determined according to the total length of the anchor cable in the engineering design; in a preferred embodiment, the lengths of the first end rigid-flexible composite unit 27, the middle rigid-flexible composite unit 26 and the last end rigid-flexible composite unit 25 are equal, all being 2.0m to 3.0m;

[0050] Preferably, the middle external threaded connection section 21, the end internal threaded connection section 19, the beginning external threaded connection section 24, and the middle internal threaded connection section 20 all employ trapezoidal or sawtooth thread structures; more preferably, the tensile bearing capacity of the threaded connections between the middle external threaded connection section 21 and the end internal threaded connection section 19, and between the beginning external threaded connection section 24 and the middle internal threaded connection section 20, is [not specified]. (Unit: kN) Verify using the following formula:

[0051] ;

[0052] In the formula, This refers to the nominal diameter of the thread (in mm). The pitch is in mm. The inner diameter of the rigid sleeve is in mm. The unit is the yield strength of the steel used in the rigid sleeve (in MPa). The tensile safety factor (with a value range of 1.5 to 2.0) This is the design value of the axial tensile force of the anchor cable (in kN); this formula is used to check the weakest section at the threaded connection to ensure that the connection strength meets the design requirements.

[0053] As a preferred embodiment, the minimum insertion sealing length between the middle socket section 15 and the end insertion section 10, and between the first end socket section 18 and the middle insertion section 22. Calculated using the following formula:

[0054] ;

[0055] In the formula, This is the maximum grouting pressure (in MPa). The outer diameter of the steel pipe for the splice section is in mm. The shear strength (in MPa) of the interface between the rigid sleeve and the borehole wall after the slurry has solidified; actual insertion length. Should meet ;

[0056] In order to form an annular grouting gap between the borehole and the rigid casing, providing an annular flow channel for subsequent grouting, the outer diameters of the end rigid casing 6, the middle rigid casing 4, and the beginning rigid casing 2 are equal and all are... The maximum diameter of the reaming drill bit 1 Greater than As a preferred option, the maximum diameter of the reaming drill bit 1 is such that it can form an annular grouting gap after reaming. ,in To allow for hole enlargement, a margin of 5–15 mm is provided so that an annular grouting gap can be formed between borehole 16 and the rigid casing.

[0057] As a preferred embodiment, the end rigid sleeve 6, the middle rigid sleeve 4, and the first end rigid sleeve 2 are all made of thick steel pipes, which ensures the support effect; the end grouting pipe 11, the middle grouting pipe 14, and the first end grouting pipe 9 are all made of thin steel pipes, which ensures the stability of the grouting channel and facilitates the smooth progress of subsequent grouting; the end flexible anchor cable section 7, the middle flexible anchor cable section 5, and the first end flexible anchor cable section 3 are all made of steel strand with hollow channels, which effectively ensures the reliable application of preload.

[0058] As a preferred embodiment, the first and last ends of the end rigid sleeve 6 are respectively fixedly connected by two end compression anchor sleeves and the first and last ends of the end flexible anchor cable segment 7; the first and last ends of the middle rigid sleeve 4 are respectively fixedly connected by two middle compression anchor sleeves and the first and last ends of the middle flexible anchor cable segment 5; and the first and last ends of the first end rigid sleeve 2 are respectively fixedly connected by two first end compression anchor sleeves and the first and last ends of the first end flexible anchor cable segment 3.

[0059] In this technical solution, the rigid casing and the flexible anchor cable are fixedly connected by compression anchoring, enabling the flexible anchor cable segment to withstand axial tensile force. This allows for the effective application of preload to each rigid-flexible composite unit, achieving active support. Furthermore, by incorporating mature technologies such as threaded connections between adjacent rigid-flexible composite units, the solution is easier to manufacture and assemble on-site. It also facilitates transportation and downhole operations, demonstrating excellent engineering practicality and economic efficiency.

[0060] Preferably, the compression anchor sleeve can be plastically deformed by hydraulic compression, thereby forming a permanent mechanical lock between the rigid sleeve and the flexible anchor cable segment; wherein, the ultimate gripping force of the compression anchor... Verification is performed using the following formula:

[0061] ;

[0062] In the formula, The nominal diameter of the flexible anchor cable segment (in mm). The effective anchorage length of the compression anchor sleeve (in mm). The equivalent bond strength at the interface between the compression anchor sleeve and the flexible anchor cable section (measured by test, with a value range of 80MPa to 120MPa). The anchorage safety factor (with a value ranging from 1.2 to 1.5) The working load for the anchor cable design (in kN) is given; this formula is used to ensure that the compression anchor section can reliably transmit the axial force of the anchor cable.

[0063] After the first rigid-flexible composite unit 27, the middle rigid-flexible composite unit 26, and the last rigid-flexible composite unit 25 are connected in sequence, an integrated composite anchor body is formed. After grouting and curing, the overall support stiffness of the integrated composite anchor body is [missing information]. Calculated using the following formula:

[0064] ;

[0065] In the formula, The axial tensile stiffness of the flexible anchor cable segment (unit: kN / mm). The axial compressive stiffness of the rigid sleeve assembly is expressed in kN / mm. Shear stiffness at the interface between the grout and the surrounding rock (unit: kN / mm). The minimum support stiffness required for engineering design (unit: kN / mm); this formula is used to evaluate the overall stiffness performance of the anchor cable system under combined stress conditions;

[0066] This invention proposes a segmented self-drilling anchor system with rigid-flexible separation and functional synergy. It innovatively decomposes the overall anchor system into multiple rigid-flexible composite units. Each composite unit is designed as a composite structure consisting of an outer rigid sleeve, an inner flexible anchor cable, and a central grouting pipe. After the rigid-flexible composite units at the end, middle, and beginning are cascaded, the entire length of the internal flexible anchor cable is protected by the outer rigid sleeve, forming a complete support structure with an outer rigidity and an inner flexibility. Furthermore, by installing a reaming drill bit at the beginning of the first-end rigid-flexible composite unit, the rigid-inner-flexible anchor system simultaneously acquires autonomous drilling capabilities. In this way, during drilling, each section of the outer rigid casing can serve as a reliable force transmission component and remain along its entire length, achieving the dual functions of effective transmission of drilling force and reliable support of the borehole wall. Simultaneously, the inner flexible anchor cable serves as a support structure for the grouting pipe and a prestressing structure. This segmented composite structure solves the technical problem of flexible anchor cables being unable to transmit drilling force. It also addresses key technical challenges such as borehole collapse, difficulty in hole formation, and the complex stress distribution of traditional self-drilling anchors in long-distance drilling in loose and fractured strata. Therefore, this invention creatively decouples and recombines the rigid casing used in casing drilling with the prestressed flexible anchor cable, solving the problem of their coordinated operation during drilling, connection, and grouting processes. This forms a novel composite structure and working mode, enabling efficient and reliable integrated drilling, anchoring, and grouting operations in loose and fractured strata.

[0067] The system has a simple structure, low manufacturing cost, convenient construction process, easy transportation and extension, and strong adaptability. It can realize integrated drilling, anchoring and injection construction of loose and broken rock layers. At the same time, it can achieve immediate support and full-length anchoring, which can improve the stability and reliability of surrounding rock support. It can be widely used in mining roadways, tunnel engineering and slope treatment.

[0068] This invention also provides a construction method for an integrated drilling, anchoring, and grouting segmented self-drilling hollow grouting anchor cable, employing an integrated drilling, anchoring, and grouting segmented self-drilling hollow grouting anchor cable system, comprising the following steps:

[0069] Step 1: Determining the drilling depth and the number of intermediate anchor cable units;

[0070] Based on the engineering geological survey report and on-site detection methods, the design depth of borehole 16 was determined. Then, based on the design depth, the number of middle rigid-flexible composite units was determined by combining the lengths of the first rigid-flexible composite unit 27, the last rigid-flexible composite unit 25 and the middle rigid-flexible composite unit.

[0071] Step 2: Drilling preparation and preliminary construction;

[0072] A reaming drill bit 1 is fixedly installed at the first end of the first end of the rigid-flexible composite unit 27. Specifically, the reaming drill bit 1 is coaxially fixed at the first end of the first end of the rigid sleeve 2. The end of the first end rigid-flexible composite unit 27 is connected to the drilling rig. Specifically, the first end external threaded connection section 24 at the end of the rigid sleeve 2 is connected to the output end of the drilling rig. The drilling rig is started to perform the first stage of drilling operation. The reaming drill bit 1 cuts the rock and soil to form a borehole 16. The synchronously advancing first end rigid sleeve 2 supports the borehole wall in real time to prevent the borehole from collapsing. The drilling stops when the first end external threaded connection section 24 reaches the borehole opening.

[0073] Step 3: Segmented connection and mid-section construction;

[0074] S31: The middle rigid-flexible composite unit 26 is coaxially connected to the end of the first rigid-flexible composite unit 27. Specifically, the middle insertion section 22 is inserted into the inside of the first sleeve section 18 to form a continuous grouting channel, and the middle internal threaded connection section 20 is fitted onto the outside of the first external threaded connection section 24 through threaded engagement to form a continuous rigid sleeve. Sufficient engagement torque is applied during the connection process to ensure that the threaded connection meets the pre-tightening requirements. The end of the middle rigid-flexible composite unit 26 is connected to the drilling rig, and the drilling rig is started to carry out the second stage of drilling operation until the middle external threaded connection section 21 reaches the borehole opening.

[0075] S32: Cascade the next intermediate rigid-flexible composite unit 26 at the end of the intermediate rigid-flexible composite unit 26. Specifically, insert the intermediate insertion section 22 of the next intermediate rigid-flexible composite unit 26 into the intermediate sleeve section 15 of the current intermediate rigid-flexible composite unit 26 to form a continuous extended grouting channel, and fit the intermediate internal threaded connection section 20 of the next intermediate rigid-flexible composite unit 26 onto the outside of the external threaded connection section 21 of the current intermediate rigid-flexible composite unit 26 through threaded engagement to form a continuous extended rigid sleeve; connect the end of the next intermediate rigid-flexible composite unit 26 to the drilling rig, start the drilling rig to perform intermediate drilling operations, and stop when the intermediate external threaded connection section 21 of the next intermediate rigid-flexible composite unit 26 reaches the borehole opening;

[0076] S33: Repeat S32 until the middle external thread connection section 21 of the last middle rigid-flexible composite unit 26 reaches the orifice.

[0077] Step 4: Final segment connection and final segment construction;

[0078] At the end of the last central rigid-flexible composite unit 26, the end rigid-flexible composite unit 25 is coaxially connected. Specifically, the end plug section 10 of the end rigid-flexible composite unit 25 is inserted into the interior of the central sleeve section 15 of the last central rigid-flexible composite unit 26 to form a full-length grouting channel. The end internal threaded connection section 19 of the end rigid-flexible composite unit 25 is fitted onto the exterior of the central external threaded connection section 21 of the last central rigid-flexible composite unit 26 through threaded engagement to form a full-length rigid sleeve. The end of the end rigid-flexible composite unit 25 is connected to the drilling rig, and the drilling rig is started to perform the final stage drilling operation until the external threaded locking section 23 reaches the borehole opening.

[0079] Step 5: Grouting operation;

[0080] Grouting anchoring material 17 is injected through the end grouting pipe 11. The grouting anchoring material 17 flows out through the grout outlet 8 and enters the annular gap between the rigid casing and the borehole 16. It gradually fills the hole from the bottom to the opening. During the reverse filling process, the grout seeps radially into the surrounding rock fissures under pressure to cement and reinforce the broken surrounding rock.

[0081] Step 6: Apply preload;

[0082] After the slurry has cured to the design strength, the tray 13 and the lock 12 are sequentially installed on the external thread locking section 23, and the design preload is applied and locked using a tensioning device.

[0083] As a preferred option, in step 5, the grouting anchoring material 17 is a cement-based grout or a chemical grout, and the grouting pressure is controlled between 0.5 MPa and 1.5 MPa.

[0084] This invention utilizes a rigid casing to transmit torque and thrust during drilling and provides real-time support to the borehole wall, effectively preventing borehole collapse in soft rock formations. Simultaneously, it leverages the support and protection provided by the flexible anchor cable section to ensure the effective penetration of the grouting pipe and the effective application of prestress for reliable anchoring, thus demonstrating the advantages of active support. Ultimately, the rigid casing remains entirely within the borehole, becoming part of the permanent support structure and forming a composite anchor body with the grout, significantly improving anchoring reliability. In weak and fractured surrounding rock, this method can substantially increase the borehole success rate, reduce borehole collapse handling time, and simultaneously achieve full-length anchoring and active support, resulting in significant comprehensive benefits.

[0085] This method effectively solves the technical problems of flexible anchor cables being unable to transmit drilling torque and thrust, and the difficulty of constructing long anchor cables in weak surrounding rock. It achieves coordinated force and deformation among the anchor cable rod, rigid sleeve, grouting body, and surrounding rock, effectively overcoming the shortcomings of existing technologies.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A segmented self-drilling hollow grouting anchor cable system integrating drilling, anchoring, and grouting, comprising a rigid-flexible composite body, a locking device (12), and a tray (13), characterized in that, It also includes reaming drill bits (1); The rigid-flexible composite structure includes an end rigid-flexible composite unit (25), a middle rigid-flexible composite unit (26), and a head rigid-flexible composite unit (27) arranged sequentially along the axial direction; the end rigid-flexible composite unit (25) includes an end grouting pipe (11), an end flexible anchor cable section (7), and an end rigid sleeve (6) that are fixedly connected sequentially from the inside to the outside; the middle rigid-flexible composite unit (26) includes a middle grouting pipe (14), a middle flexible anchor cable section (5), and a middle rigid sleeve (4) that are fixedly connected sequentially from the inside to the outside; the head rigid-flexible composite unit (27) includes an end grouting pipe (11), a middle flexible anchor cable section (5), and a middle rigid sleeve (4) that are fixedly connected sequentially from the inside to the outside; the head rigid-flexible composite unit (27) includes an end grouting pipe (11), a middle flexible anchor cable section (5), and a middle rigid sleeve (4) that are fixedly connected sequentially from the inside to the outside; the head rigid-flexible composite unit (27) includes an end grouting pipe (11), a middle flexible anchor cable section (7), and an end rigid sleeve (6 ... The composite unit (27) includes a first-end grouting pipe (9), a first-end flexible anchor cable section (3), and a first-end rigid sleeve (2) that are fixedly connected from the inside to the outside. The first and last ends of the middle grouting pipe (14) are fixedly connected to the end of the first-end grouting pipe (9) and the first end of the end grouting pipe (11), respectively. The first and last ends of the middle rigid sleeve (4) are fixedly connected to the end of the first-end rigid sleeve (2) and the first end of the end rigid sleeve (6), respectively. At least one grout outlet (8) is opened at the first end of the first-end rigid sleeve (2). The reaming drill bit (1) is coaxially fixedly installed at the head end of the rigid sleeve (2); The lock (12) and the tray (13) are sequentially fitted onto the outside of the end section of the end rigid sleeve (6), and the lock (12) and the end section of the end rigid sleeve (6) are engaged by a threaded structure. The first and last ends of the end rigid sleeve (6) are fixedly connected by two end compression anchor sleeves and the first and last ends of the end flexible anchor cable segment (7), respectively. The first and last ends of the middle rigid sleeve (4) are fixedly connected by two middle compression anchor sleeves and the first and last ends of the middle flexible anchor cable segment (5), respectively. The first and last ends of the first end rigid sleeve (2) are fixedly connected by two first end compression anchor sleeves and the first and last ends of the first end flexible anchor cable segment (3), respectively.

2. The integrated drilling, anchoring, and grouting segmented self-drilling hollow grouting anchor cable system according to claim 1, characterized in that, The outer side of the end of the rigid sleeve (6) is provided with an external threaded locking section (23) that cooperates with the lock (12), and the inner side of its head end has an internal threaded connection section (19); the outer side of the head end of the grouting pipe (11) has an end insertion section (10). The outer side of the end of the central rigid sleeve (4) is provided with a central external threaded connection section (21), and the inner side of its first end is provided with a central internal threaded connection section (20); the inner side of the end of the central grouting pipe (14) is provided with a central sleeve section (15), and the outer side of its first end is provided with a central insertion section (22); the central external threaded connection section (21) is inserted into the interior of the end internal threaded connection section (19) by thread engagement; the central sleeve section (15) is sealed and fitted onto the exterior of the end insertion section (10); The outer side of the end of the rigid sleeve (2) is provided with an external threaded connection section (24); the inner side of the end of the grouting pipe (9) is provided with a sleeve section (18); the external threaded connection section (24) is inserted into the middle internal threaded connection section (20) by threaded engagement; the sleeve section (18) is sealed and fitted onto the outside of the middle insertion section (22); the grout outlet (8) is opened at the beginning of the rigid sleeve (2) and is connected to the beginning of the grouting pipe (9) through a radial channel opened on the flexible anchor cable section (3).

3. The integrated drilling, anchoring, and grouting segmented self-drilling hollow grouting anchor cable system according to claim 1, characterized in that, The outer diameters of the end rigid sleeve (6), the middle rigid sleeve (4), and the beginning rigid sleeve (2) are equal and are all... The maximum diameter of the reaming drill bit (1) Greater than .

4. The integrated drilling, anchoring, and grouting segmented self-drilling hollow grouting anchor cable system according to claim 1, characterized in that, The end rigid sleeve (6), the middle rigid sleeve (4) and the first rigid sleeve (2) are all made of thick steel pipes; the end grouting pipe (11), the middle grouting pipe (14) and the first grouting pipe (9) are all made of thin steel pipes; the end flexible anchor cable section (7), the middle flexible anchor cable section (5) and the first flexible anchor cable section (3) are all made of steel strand with hollow channels.

5. A construction method for an integrated drilling, anchoring, and grouting segmented self-drilling hollow grouting anchor cable, comprising the integrated drilling, anchoring, and grouting segmented self-drilling hollow grouting anchor cable system as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: Determining the drilling depth and the number of intermediate anchor cable units; Based on the engineering geological survey report and on-site detection methods, the design depth of borehole (16) is determined, and then the number of rigid-flexible composite units in the middle is determined based on the design depth. Step 2: Drilling preparation and preliminary construction; A reaming drill bit (1) is fixedly installed at the first end of the first end rigid-flexible composite unit (27), and the end of the first end rigid-flexible composite unit (27) is connected to the drilling machine. The drilling machine is started to carry out the first stage of drilling operation. The reaming drill bit (1) cuts the rock and soil to form a borehole (16), and the first end rigid sleeve (2) is used to support the borehole wall in real time until the first end external threaded connection section (24) reaches the borehole opening. Step 3: Segmented connection and mid-section construction; S31: Connect the middle rigid-flexible composite unit (26) coaxially to the end of the first rigid-flexible composite unit (27), connect the end of the middle rigid-flexible composite unit (26) to the drilling machine, start the drilling machine to carry out the second stage of drilling operation, and stop when the middle external thread connection section (21) reaches the hole opening. S32: Cascade the next intermediate rigid-flexible composite unit (26) at the end of the intermediate rigid-flexible composite unit (26), connect the end of the next intermediate rigid-flexible composite unit (26) to the drilling rig, start the drilling rig to carry out intermediate drilling operations, and stop when the intermediate external thread connection section (21) reaches the hole opening. S33: Repeat S32 until the middle external thread connection section (21) of the last middle rigid-flexible composite unit (26) reaches the orifice; Step 4: Final segment connection and final segment construction; At the end of the last central rigid-flexible composite unit (26), the end rigid-flexible composite unit (25) is coaxially connected. The end of the end rigid-flexible composite unit (25) is connected to the drilling machine. The drilling machine is started to carry out the final drilling operation until the external thread locking section (23) reaches the hole opening. Step 5: Grouting operation; Grouting anchor material (17) is injected through the end grouting pipe (11). The grouting anchor material (17) flows out through the grout outlet (8) and enters the annular gap between the rigid casing and the borehole (16). It gradually fills the hole from the bottom to the opening. During the reverse filling process, the grout seeps radially into the surrounding rock fissures under pressure to cement and reinforce the broken surrounding rock. Step 6: Apply preload; After the slurry has cured to the design strength, the tray (13) and the lock (12) are sequentially installed on the external thread locking section (23), and the design pre-tightening force is applied and locked using a tensioning device.

6. The construction method of a segmented self-drilling hollow grouting anchor cable with integrated drilling, anchoring, and grouting as described in claim 5, characterized in that, In step 5, the grouting anchoring material (17) is a cement-based grout or a chemical grout, and the grouting pressure is controlled between 0.5 MPa and 1.5 MPa.

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