Self-drilling anti-floating anchor rod drilling tool structure with self-adaptive positioner and construction method

Abstract

The invention discloses a self-drilling anti-floating anchor drilling tool structure with a self-adaptive positioner and a construction method, solves the problem that in the prior art, the forming quality is affected by structural arrangement in the drilling process of an anti-floating anchor, and has the beneficial effects that wall protection and muck removal are achieved, grouting can be achieved, and centering positioning is kept in the grouting process. According to the specific scheme, the self-drilling anti-floating anchor rod drilling tool structure with the self-adaptive positioner comprises a pile casing, one end of the pile casing can be connected with a drilling machine, a front-end drill crown is detachably arranged at the other end of the pile casing, open holes are formed in the side wall of the pile casing, spiral blades are annularly arranged on the pile casing, and a plurality of anchor rod steel bars are arranged in the pile casing; one end of each anchor rod steel bar abuts against the front-end drill crown, the other end of each anchor rod steel bar is arranged to exceed the pile casing, the self-adaptive positioners are arranged in the length direction of the anchor rod steel bars at set intervals, the self-adaptive positioners are located in the pile casing, the self-adaptive positioners are arranged on the peripheral sides of the anchor rod steel bars, and the self-adaptive positioners are fixedly connected with the anchor rod steel bars.

Description

Technical Field

[0001] This invention relates to the field of anti-buoyancy engineering technology in buildings, and in particular to a self-drilling anti-buoyancy anchor drill tool structure and construction method with an adaptive locator. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] The anti-buoyancy safety of underground structures in Shenzhen has become a critical technical challenge that urgently needs to be addressed. With the increasing vertical development of cities, the construction depth of large underground transportation hubs, deep parking garages, sunken commercial complexes, integrated utility tunnels, and even deep sewage treatment plants is constantly increasing, with some projects having foundations tens of meters underground. This trend directly leads to a geometric increase in the static buoyancy force on the structural foundation, constituting a huge potential buoyancy load that constantly threatens the safety of underground structures. Once the buoyancy force exceeds the total resistance of the structure's self-weight and overlying load, it may cause deformation, cracking, and leakage of the structural base slab, leading to the failure of underground space functions, equipment damage, and shortened structural lifespan due to long-term immersion corrosion; in severe cases, it can cause uneven lifting, tilting, instability, and even serious engineering accidents such as overall buoyancy in extreme situations.

[0004] The limitations of traditional anti-buoyancy anchor construction techniques and technologies are amplified under the aforementioned high standards and complex geological conditions. The independent, step-by-step operation mode adopted, such as drilling, hole cleaning, anchor lowering, and grouting, may lead to quality control issues. This technical bottleneck is particularly pronounced in loose, easily collapsing strata such as gravel layers, high-moisture silty fine sand layers, mixed-component backfill soil, and silty soft soil, which are widely distributed in urban areas. The moment the drill rod is lifted out of the borehole after drilling, the borehole wall loses lateral support, and under the influence of soil weight and groundwater seepage pressure, it is highly susceptible to immediate borehole wall collapse or diameter reduction. This hole collapse phenomenon not only leads to serious non-compliance of the hole geometry, making it impossible to guarantee the designed anchorage length and diameter, but also has a more serious consequence: the collapsed loose soil mixes with the subsequently injected cement grout, turning what should be a pure and high-strength grout into a mixture of soil and cement grout particles with low strength and uneven distribution. This creates a weak contact surface between the anchor body and the stratum, significantly weakening the effective bond and frictional resistance between the two, making the final pull-out bearing capacity of the anchor bolt discrete and unpredictable.

[0005] CN216474989U discloses a self-drilling rod. Although this anchor rod achieves self-drilling functionality through a prefabricated steel bridge and external steel threads, it relies on a auger pile driver for drilling and does not clearly define specific solutions for grouting, soil removal, and borehole wall stability. The steel casing of the self-drilling screw anti-buoyancy anchor rod lacks a recycling design, resulting in material waste. CN107237645A proposes an improved self-drilling grouting connecting rod, which connects multiple sections of a single rod through an anti-rotation connector to meet the needs of different lengths and features a magnetic grout stop end. However, its connection structure is relatively complex, and it does not fully consider how to effectively remove excavated soil during drilling to ensure borehole stability. CN211523297U discloses a prefabricated self-drilling screw anti-buoyancy anchor rod that utilizes helical blades to enhance friction with the soil and performs grouting through an internal grouting pipe. However, its soil removal capacity mainly relies on the helical blades, which has limited efficiency in specific strata and lacks an effective mechanism to ensure the rod is centered within the borehole.

[0006] Without considering the centering of the pole, it is difficult to ensure that the flexible steel strand or rebar pole is centered throughout its entire length in a hole several meters deep, relying solely on simple positioning devices or manual experience. This results in uneven thickness of the protective layer, with some areas having insufficient protective layer. Under long-term erosion by groundwater, these areas become weak points in the corrosion protection system. Corrosive media will cause localized corrosion of the steel pole, leading to a reduction in its effective cross-section and strength. Ultimately, it may even cause brittle fracture at loads far below the design load, seriously threatening the long-term durability and safety of the structure.

[0007] In addition, in the existing technology, construction workers have to spend a lot of time on repeated secondary or even tertiary hole cleaning operations, which greatly prolongs the construction cycle of a single anchor rod, resulting in a huge waste of labor time, machinery, water and electricity resources. The cumbersome procedures also increase the complexity of on-site management and the probability of errors.

[0008] In summary, the existing anchor structures generally suffer from problems such as easy hole collapse, inability to effectively remove debris, and inability to center and position the anchor. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the purpose of this invention is to provide a self-drilling anti-buoyancy anchor drill string structure with an adaptive locator. During the casing drilling process, it can achieve wall protection and soil removal, as well as grouting and maintain centered positioning during drilling and grouting, effectively eliminating the problem of hole collapse in loose strata and ensuring anchoring quality.

[0010] To achieve the above objectives, the present invention is implemented through the following technical solution: A self-drilling anti-buoyancy anchor bolt drill string structure with adaptive positioner includes a casing, one end of which can be connected to the drilling rig, and a front drill crown detachably mounted on the other end of the casing. The casing is circumferentially equipped with helical blades, and multiple anchor bolts are installed inside the casing. One end of each anchor bolt abuts against the front drill crown, and the other end extends beyond the casing. An adaptive positioner is installed at predetermined intervals along the length of the anchor bolts, located inside the casing and positioned around the multiple anchor bolts. The adaptive positioner is fixedly connected to the anchor bolts. The adaptive positioner has blades that can open towards the sidewall of the casing. An elastic reset component is installed between the inner side of the blades and the anchor bolts to ensure that the blades always maintain contact with the inner wall of the casing, thus achieving centered positioning of the anchor bolts. The elastic reset component also facilitates the reset of the blades.

[0011] As described above, a self-drilling anti-buoyancy anchor bolt drill string structure with an adaptive locator is provided. The adaptive locator is provided with a rebar hole, and each of the anchor bolt rebars is placed in the rebar hole. The adaptive locator is welded to the anchor bolt rebar. The adaptive locator is provided with at least one grouting recess in the circumference. The grouting recess accommodates the grouting pipe so that secondary grouting can be performed after the casing is removed.

[0012] As described above, a self-drilling anti-buoyancy anchor bolt drill string structure with an adaptive positioner includes a positioning plate. The outer diameter of the positioning plate is 15mm-25mm smaller than the inner diameter of the casing. One end of the blade is connected to the positioning plate via a rotary hinge.

[0013] As described above, in a self-drilling anti-buoyancy anchor bolt drill string structure with an adaptive positioner, the rotary hinge includes a sealed radial thrust bearing. The outer ring of the sealed radial thrust bearing is welded and fixed to the positioning plate, while the inner ring is tightly connected to the connecting shaft of the blade. The elastic reset component is a spring. One end of the elastic reset component is fixed near the centroid of the blade, and the other end is welded and fixed to the anchor rod reinforcement.

[0014] As described above, a self-drilling anti-buoyancy anchor bolt drill string structure with an adaptive positioner includes at least two trapezoidal blades, with an angle set between adjacent trapezoidal blades, and the longer end of the trapezoidal blade can fit against the inner wall of the casing. The trapezoidal blade is an isosceles trapezoidal blade, and the angle between the longer end of the trapezoidal blade and the hypotenuse is 50°-80°.

[0015] As described above, in a self-drilling anti-buoyancy anchor bolt structure with an adaptive locator, the blades are offset from the grouting recess at the location of the adaptive locator.

[0016] As described above, in a self-drilling anti-buoyancy anchor drill bit structure with an adaptive positioner, the opening is located between two adjacent spiral blades, and a one-way valve diaphragm is provided at the opening.

[0017] As described above, in a self-drilling anti-buoyancy anchor drill bit structure with an adaptive positioner, a cutting blade is provided on the outer wall of the casing at one end near the front end of the drill crown. Multiple cutting blades are provided along the circumferential direction of the casing, and the spacing between adjacent cutting blades is set. The front end of the drill bit and the casing are connected by a threaded structure.

[0018] As described above, in a self-drilling anti-buoyancy anchor drill bit structure with an adaptive positioner, the helical blade is located on one side of the tunneling cutter, and the helical blade is spaced apart from the other end of the casing.

[0019] Secondly, the present invention also provides a construction method for a self-drilling anti-buoyancy anchor drill string structure with an adaptive locator, comprising the following: A spiral blade is installed around the casing, and a detachable front end drill cap is installed at the bottom of the casing. An adaptive positioner is installed at set intervals along the length of the anchor bar to insert the anchor bar into the casing. Mark the drilling holes for anchor bolts at the construction site; The casing is connected to the drilling rig. The drilling rig is started, and the assembled anchor drill tool structure is driven to rotate and drill down. During the drilling process, the front end of the drill crown and the cutting blade work together to break the rock and soil. The spiral blades continuously discharge the drill cuttings along the hole wall, while also stabilizing the hole wall. Drilling, soil removal, and wall protection are carried out simultaneously. After drilling is completed, air or water at a set pressure is injected into the casing. The air or water flows out through the opening to clean the bottom of the hole. Cement grout is pumped into the inner cavity of the casing, and the blades of the adaptive positioner are pressed against the inner wall of the casing to ensure that the anchor rod reinforcement remains centered at all times. Start the drilling rig to separate the casing from the front drill crown and rotate the casing out from underground; After the casing is pulled out, there is a gap between the borehole wall and the primary grout. Secondary grouting is then performed between the borehole wall and the primary grout.

[0020] The beneficial effects of the present invention are as follows: 1) This invention integrates the front-end drill crown, spiral blades, and casing into a single design. The casing can be rotated for tunneling as a whole, while the front-end drill crown is responsible for drilling and breaking the soil. The casing provides real-time support to the borehole wall, which helps to effectively avoid the risk of borehole collapse. The spiral blades on the casing can continuously transport the excavated soil from the bottom of the borehole to the ground, thus integrating the traditional independent steps of drilling and wall protection into a synchronous operation. Since the final anchor rod can be pre-placed in the hollow channel of the casing, the anchoring work is basically completed when the designed depth is reached. In this way, drilling, wall protection, and anchoring can be carried out in one operation, which helps to significantly simplify the construction process, shorten the construction period, and improve construction efficiency.

[0021] 2) This invention utilizes an adaptive positioner and an elastic reset component to push the blades so that they are always dynamically pressed against the hole wall. This ensures that the anchor rod reinforcement is precisely constrained to the center of the hole along its entire length, guaranteeing the uniformity of the anchor body protective layer thickness and preventing the risk of localized corrosion caused by eccentricity in the anchor rod structure. This provides a reliable guarantee for the long-term load-bearing capacity and durability of the anchor rod structure. Furthermore, a grouting recess is added to the positioning plate, creating an independent secondary grouting channel. After the initial grouting is completed, supplementary grouting or pressure grouting can be performed through the grouting pipe located in the grouting recess to effectively fill any voids that may have occurred during the initial grouting. This further improves the density and load-bearing capacity of the anchor body, meeting the more stringent quality requirements of major engineering projects and ensuring the lifespan of the anti-buoyancy anchor rod.

[0022] 3) In this invention, the front-end drill crown and the casing are connected by threads, which allows the casing to be unscrewed from underground and recycled after grouting is completed. This enables the reuse of the main steel materials, significantly reduces material costs, and meets the requirements of green and sustainable construction.

[0023] 4) In this invention, the casing is provided with an opening. By introducing high-pressure air or clean water into the casing, the high-pressure air or clean water can flow out through the opening, thus enabling the cleaning operation.

[0024] 5) By providing a construction method, this invention ensures that the final anchor drill structure remains centered during grouting, resulting in high forming quality, improved reliability and durability of the anchor drill structure, and effective improvement of construction efficiency, thus meeting the requirements of high-quality engineering in complex geological conditions. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0026] Figure 1This is a schematic diagram of a self-drilling anti-buoyancy anchor bolt drill string structure with an adaptive positioner according to one or more embodiments of the present invention.

[0027] Figure 2 This is a cross-sectional view of a self-drilling anti-buoyancy anchor bolt drill string structure with an adaptive locator according to one or more embodiments of the present invention.

[0028] Figure 3 This is an enlarged schematic diagram of the adaptive locator at the anchor rod reinforcement in a self-drilling anti-buoyancy anchor rod structure with an adaptive locator according to one or more embodiments of the present invention.

[0029] Figure 4 This is a top view of the adaptive positioner in a self-drilling anti-buoyancy anchor bolt drill string structure with an adaptive positioner according to one or more embodiments of the present invention.

[0030] The diagram exaggerates the spacing or dimensions between parts to show their positions; the diagram is for illustrative purposes only.

[0031] Among them: 1. Anchor rod reinforcement, 2. Steel casing, 3. Spiral blade, 4. Tunneling blade, 5. One-way valve hole, 6. Front drill crown, 7. Adaptive positioner, 8. Reinforcing bar hole, 9. Grouting recess, 10. Positioning plate, 11. Rotary hinge, 12. Trapezoidal blade, 13. Elastic reset assembly. Detailed Implementation

[0032] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0033] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. As described in the background section, existing anti-buoyancy anchors cannot protect the wall during drilling, cannot effectively remove soil, and cannot ensure the anchor reinforcement is centered during grouting, thus affecting the quality of the formed anchor structure. In order to solve the above technical problems, this invention proposes a self-drilling anti-buoyancy anchor drill tool structure with an adaptive positioner.

[0034] Example 1 In a typical embodiment of the present invention, reference is made to Figure 1As shown, a self-drilling anti-buoyancy anchor bolt drill bit structure with adaptive locators includes a casing, one end of which can be connected to the drilling rig, and the other end of which is detachably equipped with a front drill crown 6. The casing sidewall has an opening, and the casing is circumferentially equipped with helical blades 3. Multiple anchor bolts 1 are installed inside the casing, one end of each anchor bolt 1 abuts against the front drill crown 6, and the other end of each anchor bolt 1 extends beyond the casing. An adaptive locator 7 is arranged at predetermined intervals along the length of the anchor bolts. The adaptive locator 7 is located inside the casing and is placed around the multiple anchor bolts 1. The adaptive locator 7 is fixedly connected to the anchor bolts 1. The adaptive locator 7 is equipped with blades that can open toward the casing sidewall. The end of the blade away from the center of the adaptive locator 7 can make close contact with the inner wall of the casing to achieve the centered setting of the anchor bolts 1.

[0035] The casing is a steel casing 2, which is a hollow tubular component. The steel casing 2 is the basic component of the entire drill-anchor assembly. Its main function is to protect the borehole wall from collapse during drilling and to serve as a channel for subsequent grouting. Its outer wall is equipped with spiral blades 3 for transporting drill cuttings from the bottom of the hole to the ground. One end of the casing is equipped with a cutting blade 4 for breaking rock and soil. The end of the steel casing 2 near the cutting blade 4 is detachably equipped with a front-end drill crown 6. The pipe wall of the steel casing 2 is equipped with multiple one-way valve holes 5 for cleaning the hole and primary grouting. The one-way valve holes 5 are used for fluid ejection during high-pressure cleaning and for grout extrusion during primary grouting. In this embodiment, the steel casing 2 uses commercially available steel pipes commonly used in engineering, with specifications of 100~200 mm in diameter and 8~10 mm in wall thickness. The specific pipe length and diameter need to be selected according to the geological conditions and anti-buoyancy design.

[0036] The spiral blade 3 is made of steel with a thickness of 8 mm and a width of 20 mm. The spiral blade 3 is spirally welded along the outer wall of the casing starting from the end of the cutting blade 4. The pitch is designed to be 45~90 mm. The specific length and pitch of the spiral blade 3 are determined according to the anti-buoyancy design and the geological properties of the construction site. The core function of the spiral blade 3 is to continuously transport the rock and soil cuttings generated by the front drill crown 6 and the cutting blade 4 along the spiral path to the outside of the hole during the rotary drilling of the steel casing 2, so as to realize the simultaneous operation of soil removal and hole cleaning.

[0037] It should be noted that the tunneling blade 4 is located 300 mm above one end of the steel casing 2 and is machine-carved. The tunneling blade 4 has multiple sections along the axial direction of the steel casing 2, and the intervals between adjacent sections of the tunneling blade 4 are set. The tunneling blade 4 and the detachable front end drill crown 6 together form a composite tunneling structure, which works together at the bottom of the hole to perform preliminary cutting and crushing of the rock and soil during the drilling process.

[0038] It is easy to understand that the front-end drill cap 6 and the cutting blades 4 together constitute a composite tunneling structure, responsible for the efficient crushing and cutting of the rock and soil at the bottom of the hole. The front-end drill cap 6 is preferably made of high-strength wear-resistant alloy steel and is integrally cast. Its tunneling diameter is consistent with the opening diameter of the cutting blades 4, which is 100~200 mm. In order to achieve a recyclable connection with the steel casing 2, the outer wall of the front-end drill cap 6 is machined with an external thread of 30 mm in length and M160×4 specification, which is engaged with the end of the steel casing 2 through a threaded structure.

[0039] The one-way valve orifice 5 is a circular hole with a diameter of 30 mm and a horizontal spacing of 25 mm. The one-way valve orifice 5 is spirally distributed from the top of the spiral blade 3 along the body of the steel casing to the end, i.e., the one-way valve orifice 5 is located between adjacent spiral blades. The one-way valve orifice 5 is embedded with a silicone one-way valve diaphragm with a thickness of 0.5 mm and an opening pressure of 0.3 MPa. During the high-pressure cleaning stage after drilling, high-pressure air or clean water is allowed to be sprayed from inside the steel casing 2 to clean the residual mud and loose soil at the bottom of the hole. During the first grouting stage, the one-way valve orifice 5 serves as the outlet for cement grout, allowing cement grout to be squeezed out unidirectionally from inside the steel casing 2, filling the annular space between the steel casing 2 and the hole wall. Its built-in one-way valve diaphragm prevents backflow of mud and water from outside the hole.

[0040] refer to Figure 2 As shown, the adaptive locator 7 is installed on the anchor rod 1. Its core function is to ensure that the anchor rod 1, as the load-bearing core, is always accurately positioned in the center of the hole throughout the entire construction process and in the final anchor body, thus ensuring a uniform protective layer thickness. To ensure the centering effect of the entire anchor rod and the function of secondary grouting, an adaptive locator 7 is installed every 1500 mm along the length of the anchor rod 1.

[0041] refer to Figure 3 As shown, the adaptive positioner 7 includes a positioning plate 10, a rotary hinge 11, a trapezoidal blade 12, and an elastic reset assembly 13. These components constitute a linked mechanical system. The positioning plate 10 is the base platform of the adaptive positioner 7. A reinforcing bar hole 8 is provided in the center of the positioning plate 10. The positioning plate 10 is welded and fixed to the anchor rod 1 through the central reinforcing bar hole 8. The positioning plate 10 provides an installation base surface for other moving parts. The positioning plate 10 is provided with grouting recesses 9 in a circumferential manner. A secondary grouting channel is formed between the grouting recesses 9 and the steel casing 2. Multiple grouting recesses 9 constitute independent channels for secondary grouting, so that after the steel casing 2 is recycled, the grout can reinforce the anchor body through the grouting recesses 9.

[0042] Among them, the positioning plate 10 is a steel disc with a thickness of 8~15 mm, and its diameter is 15mm-25mm smaller than the inner diameter of the steel casing 2. The inner diameter of the steel bar hole 8 is determined according to the outer diameter of the ring-shaped part composed of multiple steel bars. refer to Figure 4As shown, there are three grouting recesses 9. The three grouting recesses 9 are equidistantly arranged in a ring on the positioning plate 10, and their positions are staggered with those of the three rotary hinges 11.

[0043] It is easy to understand that the blade is a trapezoidal blade 12, and the rotary hinge 11 is the key component that enables the trapezoidal blade 12 to pivot around the positioning plate 10. The rotary hinge 11 ensures that the blade can open and close adaptively without obstruction according to changes in the borehole wall. The rotary hinge 11 adopts a sealed radial thrust bearing with built-in high-precision steel balls and wear-resistant cage, and is encapsulated with a dustproof and corrosion-resistant sealing ring to adapt to the working environment inside the borehole filled with mud. Its outer ring is welded and fixed to the positioning plate 10, and its inner ring is tightly connected to the connecting shaft of the trapezoidal blade 12, providing low-friction and high-load support for the flexible swing of the trapezoidal blade.

[0044] In addition, the trapezoidal blade 12 is a special steel sheet with a length of 150 mm to 200 mm and a thickness of 1.2 mm. Its short side is movably connected to the positioning plate 10 through the rotary hinge 11. The trapezoidal blade 12 is movably connected to the edge of the positioning plate 10 through the rotary hinge 11. Under the thrust provided by the elastic reset component 13, the wide side of the trapezoidal blade 12 will open outward and always dynamically stick to the hole wall. It is the direct execution component for realizing the centering positioning function.

[0045] Specifically, the elastic reset component 13 is the power source that provides radial tension to the adaptive positioner 7. The elastic potential energy it generates can be converted into a continuous thrust on the trapezoidal blade 12, making it fit tightly against the bore wall. The elastic reset component 13 is preferably a tension spring made of high-strength stainless steel. Its elastic coefficient is calculated to ensure that it can provide sufficient reset force within the maximum stroke range of the blade. One end of the elastic reset component 13 is fixed near the centroid of the trapezoidal blade 12, and the other end is welded and fixed to the anchor rod 1 to form a reset device.

[0046] The anchor drilling tool structure provided in this embodiment integrates the front-end drill crown 6, the cutting blade 4, the auger blade 3, and the steel casing 2 into a single design. Driven by an external drilling rig, the integrated drilling tool can achieve overall rotary excavation. The front-end drill crown 6 and the cutting blade 4 are responsible for drilling and breaking the soil, while the steel casing 2 provides real-time support to the borehole wall, effectively preventing the risk of borehole collapse. Simultaneously, the auger blade 3 located on the outer wall of the steel casing 2 can continuously transport the excavated soil from the bottom of the borehole to the surface, thus integrating the traditional independent steps of drilling, wall protection, and borehole cleaning into a single synchronous operation. Since the final anchor bolt structure can be pre-placed inside the steel casing 2, the anchoring work is essentially completed when the designed depth is reached. In this way, drilling, borehole cleaning, wall protection, and anchoring can be performed in one operation, significantly simplifying the construction process, shortening the construction period, and improving construction efficiency.

[0047] Example 2 This embodiment provides the following: (1) Construction preparation and parameter determination: Based on the engineering geological survey report and anti-buoyancy design requirements, determine the specifications, grade and quantity of anchor reinforcement 1, as well as the key parameters such as the pipe length, pipe diameter and wall thickness of steel casing 2. Combined with the geological characteristics, clarify the geometric dimensions and material requirements of the spiral blade 3, the tunneling cutter 4 and the front end drill crown 6.

[0048] (2) Anchor bolt processing and assembly: Thick-walled seamless steel pipes conforming to design parameters are selected as steel casing 2. Within 300 mm of its end, the tunneling blade 4 is engraved using a CNC machine tool. At the end of the inner wall of the steel casing, an M160×4 internal thread is machined for detachable connection with the front drill crown 6. The spiral blade 3 is made of wear-resistant steel plate conforming to the standard and is fully welded along the outer wall of the pipe with the designed pitch. One-way valve holes 5 with a diameter of 30 mm and a horizontal spacing of 25 mm are machined on the steel casing 2 according to the design requirements, and a silicone one-way valve diaphragm with an opening pressure of 0.3 MPa is tightly embedded to ensure one-way injection of grout during grouting. The anchor bolt steel bars 1 conforming to the specifications are passed through the steel bar holes 8 of the adaptive locator 7 according to the designed quantity and layout, and are firmly fixed to the steel positioning plate 10 with a thickness of 15 mm to 20 mm by welding.

[0049] Along the length of the anchor rod 1, an adaptive locator 7 is installed and fixed every 1500 mm to ensure the centering effect of the anchor rod and the function of secondary grouting. The trapezoidal blade 12, the rotary hinge 11, and the elastic reset component 13 on the adaptive locator 7 must be installed in place to ensure free movement. The processed steel bar bundle is carefully placed into the hollow cavity of the steel casing 2, and the specially made steel front drill crown 6 is screwed tightly to the internal thread at the end of the steel casing 2 to complete the assembly of the integrated drill-anchor assembly.

[0050] (3) Site positioning and equipment placement: Using measuring instruments such as a total station, the hole position of each anchor rod is accurately marked on the construction site, and the plane position deviation is less than or equal to 20mm. The anchor drilling rig is moved to the designated position and the centering and leveling are completed to ensure that the output shaft of the drilling rig power head is accurately aligned with the center of the hole position, and the verticality deviation is less than 1%.

[0051] (4) Self-drilling: Start the drilling rig and drive the assembled anchor drill string structure to rotate and drill downwards. During the drilling process, the front end drill crown 6 and the cutting blade 4 work together to break the rock and soil, and the spiral blades 3 on the outer wall continuously discharge drill cuttings along the hole wall, while also stabilizing the hole wall, so that drilling, soil removal and wall protection are carried out simultaneously. The drilling process is monitored throughout using equipment such as a theodolite to ensure that the verticality of the anchor bolt meets the design requirements until the design depth is reached.

[0052] (5) High-pressure hole cleaning: After the drilling operation is completed, high-pressure air or clean water is injected into the steel casing 2 through the grouting pipeline. The fluid is sprayed out from the one-way valve hole 5 on the pipe wall, which powerfully flushes out the loose soil and mud remaining in the hole, completing the hole cleaning operation and providing a clean bonding surface for subsequent grouting.

[0053] (6) First grouting: First grouting begins immediately after hole cleaning. Cement grout is pumped into the inner cavity of the steel casing 2 using a grouting pump. Under pressure, the cement grout is squeezed out from the one-way valve hole 5 and fills the annular space between the steel casing and the hole wall from bottom to top. During grouting, the trapezoidal blades 12 of the adaptive positioner 7 dynamically adhere to the hole wall under the action of the elastic reset component 13, ensuring that the anchor rod 1 remains centered at all times.

[0054] (7) Casing recovery: After the grout from the first grouting reaches the initial setting strength specified in the design (2-4 hours), because the front end of the drill crown 6 is fixed, the drilling rig is started to rotate in the reverse direction to pull the steel casing 2 out from underground. The recovered components can be used for the construction of the next anchor rod after cleaning. At this time, the semi-finished anchor rod composed of the anchor rod reinforcement 1 and the initial setting grout remains permanently in the stratum.

[0055] (8) Secondary high-pressure grouting: After the steel casing 2 is pulled out, there may be gaps between the hole wall and the primary grout. At this time, secondary high-pressure grouting is carried out immediately. Through the grouting pipeline of the grouting recess 9 on each positioning plate 10, the high-pressure grout is delivered to the gap between the primary grout and the hole wall to realize supplementary pressure grouting for the entire length of the anchor rod, so as to fill the small gaps and improve the final density and bonding strength of the anchor body.

[0056] (9) Curing and testing: After the anchor bolts are installed, they shall be moistened for no less than 7 days. After the grout strength reaches 100% of the design requirements, a set proportion of the anchor bolt structure shall be selected for basic tests or acceptance tests to test whether its ultimate pull-out bearing capacity meets the design requirements.

[0057] (10) Sealing and handover: After passing the inspection, the anchor bolt holes shall be sealed, excess anchor bolt reinforcement shall be cut off, and the anchor bolts shall be connected to the reinforcement of the foundation slab or anchor head construction shall be reserved according to the design drawings to ensure that the pull-out force can be effectively transferred to the superstructure. After all procedures are completed, relevant construction and inspection records shall be organized and the procedures shall be handed over.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A self-drilling anti-buoyancy anchor bolt drill string structure with an adaptive positioner, characterized in that, The system includes a casing, one end of which can be connected to the drilling rig, and the other end of which is detachably fitted with a front drill crown. The casing is circumferentially fitted with helical blades. Multiple anchor bars are installed inside the casing, with one end of each anchor bar abutting against the front drill crown and the other end extending beyond the casing. An adaptive locator is installed at predetermined intervals along the length of the anchor bars, located inside the casing and positioned around the anchor bars. The adaptive locator is fixedly connected to the anchor bars. Each adaptive locator has blades that can open towards the casing sidewall. An elastic reset component is installed between the inner side of the blades and the anchor bars to ensure that the blades remain in contact with the inner wall of the casing, thus achieving centered positioning of the anchor bars.

2. The self-drilling anti-buoyancy anchor bolt drill string structure with adaptive locator according to claim 1, characterized in that, The adaptive locator is provided with a rebar hole, and each of the anchor rod rebars is placed in the rebar hole. The adaptive locator is welded to the anchor rod rebar. The adaptive locator is provided with at least one grouting recess in the circumference, which accommodates the grouting pipe so that secondary grouting can be performed after the casing is removed.

3. The self-drilling anti-buoyancy anchor bolt drill string structure with adaptive locator according to claim 1, characterized in that, The adaptive positioner includes a positioning plate, the outer diameter of which is 15mm-25mm smaller than the inner diameter of the casing, and one end of the blade is connected to the positioning plate via a rotary hinge.

4. The self-drilling anti-buoyancy anchor bolt drill string structure with adaptive locator according to claim 3, characterized in that, The rotary hinge includes a sealed radial thrust bearing. The outer ring of the sealed radial thrust bearing is welded and fixed to the positioning plate, while the inner ring is tightly connected to the connecting shaft of the blade. The elastic reset component is a spring. One end of the elastic reset component is fixed near the centroid of the blade, and the other end is welded and fixed to the anchor rod reinforcement.

5. The self-drilling anti-buoyancy anchor bolt drill string structure with adaptive locator according to claim 1, characterized in that, The blade includes at least two trapezoidal blades, with an angle set between adjacent trapezoidal blades, and the longer end of the trapezoidal blade can fit against the inner wall of the protective cylinder; The trapezoidal blade is an isosceles trapezoidal blade, and the angle between the longer end of the trapezoidal blade and the hypotenuse is 50°-80°.

6. The self-drilling anti-buoyancy anchor bolt drill string structure with adaptive locator according to claim 2, characterized in that, The blade is positioned at a location offset from the grouting recess in the adaptive positioner.

7. The self-drilling anti-buoyancy anchor bolt drill string structure with adaptive locator according to claim 1, characterized in that, The side wall of the casing is provided with an opening, which is located between two adjacent spiral blades, and a one-way valve diaphragm is provided at the opening.

8. The self-drilling anti-buoyancy anchor bolt drill string structure with adaptive locator according to claim 1, characterized in that, The outer wall of the casing is provided with a tunneling blade at one end near the front drill crown. Multiple tunneling blades are provided along the circumference of the casing, and the distance between two adjacent tunneling blades is set. The front end of the drill bit and the casing are connected by a threaded structure.

9. A self-drilling anti-buoyancy anchor bolt drill string structure with an adaptive positioner according to claim 8, characterized in that, The helical blade is located on one side of the tunneling blade, and the helical blade is spaced apart from the other end of the casing.

10. A construction method for a self-drilling anti-buoyancy anchor bolt drill string structure with an adaptive locator according to any one of claims 1-9, characterized in that, Includes the following: A spiral blade is installed around the casing, and a detachable front end drill cap is installed at the bottom of the casing. An adaptive positioner is installed at set intervals along the length of the anchor bar to insert the anchor bar into the casing. Mark the drilling holes for anchor bolts at the construction site; The casing is connected to the drilling rig. The drilling rig is started, and the assembled anchor drill tool structure is driven to rotate and drill down. During the drilling process, the front end of the drill crown and the cutting blade work together to break the rock and soil. The spiral blades continuously discharge the drill cuttings along the hole wall, while also stabilizing the hole wall. Drilling, soil removal, and wall protection are carried out simultaneously. After drilling is completed, hole cleaning is performed. Cement grout is pumped into the inner cavity of the casing, and the blades of the adaptive positioner are pressed against the inner wall of the casing to ensure that the anchor rod reinforcement remains centered at all times. Start the drilling rig to separate the casing from the front drill crown and rotate the casing out from underground; After the casing is pulled out, there is a gap between the borehole wall and the primary grout. Secondary grouting is then performed between the borehole wall and the primary grout.

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