Hard rock stratum pile foundation annular drilling construction method and construction device

Abstract

This invention provides a method and apparatus for constructing ring-hole pile foundations in hard rock formations. After site leveling and equipment placement, a central hole is drilled at the center of the pile foundation to create free space. A rotary drilling rig is used to drive a swivel casing for segmented ring drilling, causing the hard rock mass to fracture and form segments. After lowering the cable wedge assembly, a vertical churning action is used to lock the wedge blocks into the rock mass. During construction, the swivel casing and cable wedge assembly are simultaneously hoisted and transported to remove the rock blocks. Vibration disturbance completes the unloading operation, and the process is repeated until the pile foundation hole is formed. This invention solves the technical problems of weak geological adaptability, difficulty in controlling rock mass fragmentation and removal, and poor overall construction performance in existing hard rock pile foundation drilling construction techniques.

Description

Technical Field

[0001] This invention relates to the field of pile foundation drilling and construction technology, and in particular to a method and apparatus for constructing ring boreholes for pile foundations in hard rock formations. Background Technology

[0002] In the field of building pile foundation construction, hard rock strata are a common and complex construction strata. They are characterized by high rock hardness, strong integrity, and high surrounding rock stress, which greatly increases the difficulty of pile foundation drilling.

[0003] Currently, domestic hard rock pile foundation drilling construction mainly adopts percussion drilling, rotary drilling, and conventional full-rotation casing drilling. Among them, percussion drilling relies on impact to break the rock, resulting in large vibration amplitude, low hole formation efficiency, and the generation of a large amount of rock debris during construction. The removal of sediment at the bottom of the hole is difficult, and the disturbance to the surrounding soil is significant. Rotary drilling is suitable for hard rock conditions, but the drill bit and drill teeth wear rapidly, resulting in high construction costs. In hard rock strata, problems such as drilling deviation and hole wall damage are prone to occur. Although conventional full-rotation casing drilling can achieve casing protection operations, the controllability of rock fracture during circumferential cutting and breaking is poor, and the rock is easily broken into irregular blocks, making it difficult to form regular blocky rock masses. There is no auxiliary locking structure inside the hole, making it difficult to extract large rock blocks. During construction, problems such as rock block slippage and casing jamming frequently occur, which not only affect the construction progress, but also pose a risk of damage to construction equipment from falling rock blocks.

[0004] Meanwhile, most existing processes rely on continuous crushing and grinding to process rocks, resulting in high construction noise, high energy consumption, and a large amount of waste soil discharged after construction, making the construction environmentally unfriendly. Summary of the Invention

[0005] The main objective of this invention is to provide a method and apparatus for constructing ring boreholes for pile foundations in hard rock formations, thereby solving the problems of weak geological adaptability, rock fragmentation, and difficulty in clearing existing drilling techniques for pile foundations in hard rock formations.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for constructing ring-hole pile foundations in hard rock strata, the method comprising: S1. Level and compact the pile foundation construction site, complete the pile position coordinate measurement and layout according to the design drawings, and accurately determine the center point of the pile foundation and the borehole outline range. S2. Lay roadbed plates in the pile location area after the layout is completed, hoist the full-rotation drilling rig to the top of the roadbed plate and position it, adjust the position of the full-rotation drilling rig and correct the verticality of the whole machine. S3. Vertically drill a central hole at the center point of the pile foundation; S4. The rotary cutting casing is placed outside the central hole. The rotary cutting casing is continuously rotated by the full-rotation drilling rig. At the same time, the axial feed of the rotary cutting casing is controlled to press down. The hard rock strata are cut in segments in a ring, so that the rock mass is broken into multiple independent rock blocks after being ring-cut. S5. Using hoisting equipment, place the cable wedge assembly into the central hole and lower it to the height range of the rock block to be cut in that segment; S6. The cable wedge assembly of the traction equipment performs a vertical, jerky, reciprocating traction action, causing several wedges on the assembly to be thrown out radially and wedge into the gaps of the fractured rock blocks to form a mechanical self-locking mechanism. S7. Control the full-rotation drilling rig to release the clamp on the rotary cutting casing. The rotary cutting casing and the cable wedge assembly are hoisted synchronously. After the rock segment is brought out of the pile foundation hole as a whole, the locking of the cable wedge assembly is released to complete the unloading of the rock segment. S8. Lift the rotary cutting sleeve back into the pile foundation hole and repeat steps S4-S7 until all segment pile foundation drilling operations are completed.

[0007] In the preferred embodiment, in step S3, an independent small drilling device is used to vertically drill and form a central hole. The diameter of the central hole is 1 / 6 to 1 / 5 of the inner diameter of the rotary cutting casing, and the diameter is not less than 100 mm. This is used to provide an inner free space for the ring cutting and fracturing of hard rock strata.

[0008] In the preferred embodiment, in step S4, the full-rotation drilling rig drives the rotary cutting casing to rotate at a constant speed, while controlling the rotary cutting casing to feed axially downward at a low constant rate, and adopting a segmented feeding method to carry out annular drilling. The segmented feed length is set to 0.8-1.2 times the inner diameter of the rotary cutting sleeve. After each segment is completed, the axial feed is paused, and the rotary cutting sleeve is kept rotating so that the hard rock mass fractures along the circumferential surface to a suitable fracture height.

[0009] In the preferred embodiment, in step S4, when the rotary cutting sleeve completes the axial segmented feeding and maintains rotation, the vertical jerking reciprocating pulling action of the cable wedge assembly is started, so that the wedge blocks of the cable wedge assembly are thrown out radially and wedge into the gaps that have just formed in the rock block, thereby achieving the matching and coordination of the timing of the wedge blocks being thrown out and wedged in with the timing of rock mass fracturing.

[0010] In the preferred embodiment, the vertical pausing reciprocating traction action adopts a constant high-frequency small-amplitude reciprocating mode, with a single traction stroke of 1 / 10 to 1 / 8 of the inner diameter of the rotary cutting sleeve.

[0011] In the preferred embodiment, the tension fluctuation data of the traction equipment is collected in real time during the traction operation. When the tension fluctuation amplitude continues to narrow and remains stable at the preset pause cycle, it is determined that the wedge and the rock block have formed an effective engagement, and then the pause traction action is terminated.

[0012] In the preferred embodiment, in step S7, the hoisting platform of the cable wedge assembly is fixedly connected to the matching hanger of the rotary cutting sleeve, and the two are simultaneously lifted and transported to the rock block inside the rotary cutting sleeve; After the rotary cutting sleeve is hoisted and removed from the pile foundation borehole, the drive cable wedge assembly generates vibration disturbance, breaking the clamping and limiting structure between the rock blocks and between the rock blocks and the inner wall of the sleeve, so that the rock blocks are removed from the rotary cutting sleeve to complete the unloading operation.

[0013] In a preferred embodiment, a construction device for a method of constructing a ring borehole for pile foundations in hard rock formations includes a full-rotation drilling rig comprising a fixed base and a lifting base, wherein the fixed base is fixed to the top surface of the roadbed plate. The roadbed plate, the fixed seat and the lifting seat are provided with a through hole that is coaxial with the center of the pile foundation, and the inner diameter of the through hole is larger than the design size of the pile foundation hole. Lifting hydraulic cylinders are vertically arranged at the four corners of the fixed base. The telescopic ends of the lifting hydraulic cylinders are fixedly connected to the corresponding positions of the lifting base. The lifting hydraulic cylinders drive the lifting base to rise and fall vertically relative to the fixed base. A clamping assembly is provided circumferentially at the through hole of the lifting seat. The telescopic end of the clamping assembly is radially pressed against the outer wall of the rotary cutting sleeve to achieve fixed clamping. The rotary assembly drives the clamping assembly to rotate along the vertical central axis of the rotary cutting sleeve.

[0014] In the preferred embodiment, the cable wedge assembly includes a wedge block, a hanging plate, and a tension cable; One end of the traction cable is fixedly connected to the hanging platform, and the other end is fixedly connected to the wedge block; Multiple sets of tension cables, along with corresponding wedges, are laid out circumferentially around the hanging platform. The lengths of each set of tension cables are different, so that all the wedges form a staggered arrangement structure with different heights and different circumferential angles in space. A tension sensor is also installed at the connection between the traction cable and the hoisting platform to collect tension data in real time during the traction operation. The outer diameter of the hanging plate is smaller than the inner diameter of the central hole; The top of the hoisting platform is connected to the output end of the winch. The winch drives the hoisting platform to move vertically back and forth through the winding and pulling action, which in turn drives the traction cable to drive the wedge block to complete the vertical jerking and disturbance action.

[0015] In the preferred embodiment, the rotary cutting sleeve is a hollow straight cylinder structure, with several cutting edges evenly fixed at its lower end. The top of the rotary cutting sleeve is equipped with several lifting lugs, which are connected to the matching hanger by steel wire rope. The hanger is connected to the hoisting equipment to achieve vertical hoisting. The cable wedge assembly is equipped with a hook at the top, which is detachably fixed to the hanger by a steel wire rope. This allows the rotary cutting sleeve and the cable wedge assembly to be lifted and transported synchronously using the same hanger.

[0016] This invention provides a method and apparatus for constructing ring-hole pile foundations in hard rock formations. Applied to pile foundation drilling in hard rock formations, this invention improves the controllability of rock fragmentation, enabling the hard rock to form a regular blocky structure after ring cutting, avoiding chaotic rock fragmentation and reducing the difficulty of rock block removal. The central hole formed during construction provides internal free space for the hard rock, effectively releasing surrounding rock stress, reducing the cutting resistance of the rotary casing, minimizing casing jamming and drilling rig overload, and making cutting operations smoother.

[0017] The cable wedge assembly can promptly wed into rock fissures during rock fracture, forming a mechanical self-locking mechanism. Combined with the clamping action of the rotary cutting sleeve and the interlocking effect between rock blocks, this multi-strength structure ensures greater stability during rock block hoisting, reducing the risk of rock blocks slipping or falling, and lowering the probability of damage to construction equipment. The rotary cutting sleeve and cable wedge assembly are hoisted synchronously, with no relative displacement between them during hoisting. This prevents the locking structure from loosening. After the rock block exits the borehole, unloading can be completed through vibration, simplifying the unloading operation and reducing manual labor.

[0018] This construction method eliminates the need for mud slurry wall support and continuous rock crushing and grinding, completing the construction by removing large, integral pieces of rock. This reduces the amount of excavated soil and improves the environmental friendliness of the construction process. The operation involves less vibration and noise, with minimal disturbance to the surrounding strata, making it suitable for a wider range of construction scenarios. It also reduces the wear rate of drilling tools, decreases the input of construction consumables, and minimizes the risk of deviation and borehole wall damage during pile foundation drilling, improving borehole quality and construction stability. Overall, it is well-suited for construction in hard rock formations, balancing construction efficiency and operational safety. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a structural diagram of the full-rotation drilling rig layout of the present invention; Figure 2 This is a schematic diagram of the pre-drilling of the center hole in this invention; Figure 3 This is a structural diagram of the segmented circumferential cutting operation and cable wedge assembly layout of the present invention; Figure 4 This is a structural diagram of the rotary cutting sleeve and rock block hoisting hole of the present invention; Figure 5 This is a flowchart of the construction method of the present invention.

[0020] In the diagram: 1. Roadbed plate; 2. Full-rotation drilling rig; 201. Fixed base; 202. Lifting base; 203. Lifting hydraulic cylinder; 204. Clamping assembly; 205. Rotary assembly; 3. Center hole; 4. Rotary cutting sleeve; 401. Cutting edge; 402. Lifting lug; 5. Cable wedge assembly; 501. Wedge block; 502. Lifting plate; 503. Pull cable; 504. Lifting hook; 6. Hanger; 7. Tension sensor; 8. Winch. Detailed Implementation

[0021] Example 1 like Figure 1-5 As shown, a method for constructing ring-hole pile foundations in hard rock formations includes: S1. Level and compact the pile foundation construction site, complete the pile position coordinate measurement and layout according to the design drawings, and accurately determine the center point of the pile foundation and the borehole outline range. S2. Lay roadbed plate 1 in the pile position area after the layout is completed, hoist the full rotary drilling rig 2 to the top of the roadbed plate 1 and position it, adjust the position of the full rotary drilling rig 2 and correct the verticality of the whole machine. S3. Vertically drill a central hole 3 at the center point of the pile foundation; S4. The rotary cutting sleeve 4 is fitted outside the central hole 3. The rotary cutting sleeve 4 is driven to rotate continuously by the full-rotation drilling rig 2. At the same time, the axial feed of the rotary cutting sleeve 4 is controlled to press down, and the hard rock strata are cut in a segmented ring-shaped drilling and cutting manner, so that the rock mass is broken into multiple independent rock blocks after being ring-cut. S5. Using hoisting equipment, the cable wedge assembly 5 is placed into the central hole 3 and lowered to the height range of the rock block 4 to be cut in that segment; S6. The cable wedge assembly 5 of the traction equipment performs a vertical, jerky, reciprocating traction action, causing several wedges 501 on the assembly to be thrown out radially and wedge into the gaps of the fractured rock to form a mechanical self-locking mechanism. S7. Control the full-rotation drilling rig 2 to release the clamp on the rotary cutting sleeve 4. The rotary cutting sleeve 4 and the cable wedge assembly 5 are hoisted synchronously. After the rock segment is brought out of the pile foundation hole as a whole, the locking of the cable wedge assembly 5 is released to complete the unloading of the rock segment. S8. Lift the rotary cutting sleeve 4 back into the pile foundation hole, and repeat steps S4-S7 until all segment pile foundation drilling operations are completed.

[0022] This application's construction process utilizes a full-rotation drilling rig 2 paired with a rotary cutting casing 4 to complete circumferential cutting operations. A center hole 3 is pre-drilled at the pile core location to create an inner free surface. The hard rock is then cut into fixed-height block structures using a segmented rotary cutting method with the casing. During operation, the shearing and pulling action of the cable wedge assembly 5 coordinates with the wedge self-locking at the moment the rock block is formed. The rock block is hoisted using a triple structure of casing friction, rock block interlocking force, and wedge locking force. The entire equipment adopts a synchronous hoisting structure, and automatic unloading is achieved through slight vibration after exiting the borehole. This scheme eliminates the need for mud wall protection and crushing into powdery soil. It relies on physical circumferential cutting and large-block, integral rock removal, resulting in low construction noise and minimal disturbance to the formation. It also effectively reduces the probability of rock falling, casing jamming, and equipment damage during hard rock drilling, exhibiting strong overall construction stability and site adaptability.

[0023] In the preferred embodiment, in step S3, an independent small drilling device is used to vertically drill and form a central hole 3. The diameter of the central hole 3 is 1 / 6 to 1 / 5 of the inner diameter of the rotary cutting sleeve 4, and the diameter is not less than 100 mm, which is used to provide an inner free space for the ring cutting and fracturing of hard rock strata.

[0024] The central hole 3 serves as an auxiliary pressure relief structure in this process. Strict verticality control is not required; a vertical cavity only needs to be formed near the pile core. The hole diameter is limited to 1 / 6 to 1 / 5 of the inner diameter of the rotary cutting casing 4, with a minimum diameter of 100mm. This size design primarily balances stress release effectiveness and rock formation quality. If the central hole 3 diameter is too large, the wall thickness of the annular rock layer will be too small, causing the rock to easily fragment into small gravel during circumferential cutting, failing to form large, intact blocks. These gravel fragments are not only difficult to self-lock but also prone to sliding back to the bottom of the hole. If the hole diameter is too small, the inner free surface is insufficient, the confining pressure of the hard rock cannot be effectively released, and the casing cutting resistance increases significantly, easily leading to casing jamming and drilling rig overload. This size range can stably break the triaxial confining pressure of hard rock, providing space for inward deformation and fragmentation of the rock mass, and is suitable for most hard rock formation construction conditions.

[0025] In the preferred embodiment, in step S4, the full-rotation drilling rig 2 drives the rotary cutting sleeve 4 to rotate at a constant speed and uniform speed, while controlling the rotary cutting sleeve 4 to feed axially downward at a low constant speed, and adopting a segmented feeding method to carry out annular drilling. The segmented feed length is set to 0.8-1.2 times the inner diameter of the rotary cutting sleeve 4. After each segment is fed, the axial feed is paused, and the rotary cutting sleeve 4 is kept rotating so that the hard rock mass fractures along the circumferential surface to a suitable fracture height.

[0026] The segmented annular drilling method employed during construction, along with uniform rotation and low-speed downward pressure, is an optimized design based on the mechanical properties of hard rock. Hard rock is brittle and highly compressive; continuous, uninterrupted downward pressure can easily cause cutting edge damage. Uniform rotation allows for even wear of the casing's circumferential cutting edge 401, avoiding localized stress concentration. The segmented feed length is set between 0.8 and 1.2 times the casing's inner diameter to match the rock's fracture formation characteristics. Rock blocks within this height range have moderate self-weight and, after tilting inside the casing, can form an interlocking structure that abuts against each other. After each segment is fed, downward pressure is paused while rotation is maintained. During this time, the casing cutting edge continuously grinds the bottom cracks of the rock block, allowing the rock to slowly generate stress concentration along the annular cutting surface, naturally fracturing and breaking apart without the need for violent crushing. This protects the equipment and ensures that each rock block has a regular shape, facilitating subsequent locking and hoisting.

[0027] In the preferred embodiment, in step S4, when the rotary cutting sleeve 4 completes the axial segmented feeding and maintains rotation, the vertical jerking reciprocating pulling action of the cable wedge assembly 5 is started, so that the wedge block 501 of the cable wedge assembly 5 is thrown out radially and wedges into the gap just formed in the rock block, so as to achieve the matching coordination between the timing of the wedge block 501 being thrown out and wedged into and the timing of rock mass fracturing.

[0028] In the preferred embodiment, the vertical pausing reciprocating traction action adopts a constant high-frequency small-amplitude reciprocating mode, and the single traction stroke is 1 / 10 to 1 / 8 of the inner diameter of the rotary cutting sleeve 4.

[0029] The timing for initiating the jerking pull of the cable wedge assembly 5 is chosen to be during the stage after segmented feeding is completed and the casing is maintaining rotation, rather than after the rock fractures. The wedge block 501 relies on the vertical jerking inertia of the pull cable 503 to achieve radial dispersion. This dispersion process requires a certain reciprocating time and cannot be completed instantaneously. Initiating the pull action in advance allows the wedge block 501 to complete its attitude adjustment and outward swing before the rock fracture forms. At the moment the rock fractures and the crack opens, the wedge block 501 can smoothly embed itself into the crack. The single pull stroke is controlled to be 1 / 10 to 1 / 8 of the casing's inner diameter. This ensures sufficient centrifugal inertia for the wedge block to disperse while avoiding excessive swing amplitude that could impact the wall of the central hole 3, thus reducing component wear.

[0030] In the preferred embodiment, the tension fluctuation data of the traction equipment is collected in real time during the traction operation. When the tension fluctuation amplitude continues to narrow and remains stable at the preset pause cycle, it is determined that the wedge block 501 and the rock block gap have formed an effective engagement, and then the pause traction action is terminated.

[0031] Due to the poor working environment and limited viewing angle inside the borehole, it is inconvenient to observe the wedging status with the naked eye. Therefore, this process uses the change in tension fluctuation as the criterion for stopping the jerking traction. In the initial stage of construction, the wedge 501 swings randomly and impacts the rock wall, resulting in large fluctuations in the tension value. As some wedges 501 embed into the rock crevices and form a binding constraint, the component's swaying amplitude decreases, and the tension fluctuation continues to narrow and tends to stabilize. This judgment method does not require all wedges 501 to be fully inserted, adapting to the real working condition of random binding inside the borehole, and the judgment logic conforms to the monitoring conditions at the construction site. After the jerking action stops, the winch 8 slightly tightens the traction cable 503, maintaining a slight tension and reserving pre-tension force to prevent the wedges 501 from loosening and slipping during hoisting, further improving the locking stability.

[0032] In the preferred embodiment, in step S7, the lifting platform 502 of the cable wedge assembly 5 is fixedly connected to the matching hanger 6 of the rotary cutting sleeve 4, and the two are simultaneously lifted and transported to the rock block inside the rotary cutting sleeve 4. After the rotary cutting sleeve 4 is lifted and removed from the pile foundation hole, the drive cable wedge assembly 5 generates vibration and disturbance, breaking the clamping and limiting structure between the rock blocks and between the rock blocks and the inner wall of the sleeve, so that the rock blocks are removed from the rotary cutting sleeve 4 to complete the unloading operation.

[0033] During hoisting, the rock blocks inside the casing interlock due to their own tilting and compression. Simultaneously, the outer wall of the rock blocks and the inner wall of the rotary cutting casing 4 generate contact friction, further enhanced by the mechanical self-locking of the cable wedge assembly 5. This multi-layered force distributes the weight of the rock blocks, preventing rockfall due to the failure of a single locking structure. The cable wedge assembly 5 is fixed to the hanger 6 for synchronous hoisting because the winch 8 only handles jerking motion and has limited vertical load-bearing capacity and structural rigidity, making it unable to bear the weight of large hard rocks alone. The shared hanger 6 ensures no relative displacement between the casing and the cable wedge assembly 5, preventing misalignment and loosening of the locking structure. After the rock blocks are hoisted out of the hole, a slight swing of the cable wedge assembly 5 generates minor vibrations, which breaks down the compressive stress between the rock blocks and between the rock blocks and the inner wall of the casing, eliminating rock jamming and facilitating automatic rock detachment and unloading. This reduces the workload of manual cleaning and prevents residual rock fragments from falling and damaging the bottom components of the drilling rig.

[0034] Example 2 Further explanation in conjunction with Example 1, such as Figure 1-5 As shown, a construction device for a method of constructing a ring borehole for pile foundations in hard rock formations includes a full-rotation drilling rig 2 with a fixed base 201 and a lifting base 202. The fixed base 201 is fixed to the top surface of the roadbed plate 1. The roadbed plate 1, the fixed seat 201 and the lifting seat 202 are provided with through holes that are coaxial with the center of the pile foundation, and the inner diameter of the through holes is larger than the design size of the pile foundation hole. Lifting hydraulic cylinders 203 are vertically arranged at the four corners of the fixed base 201. The telescopic ends of the lifting hydraulic cylinders 203 are fixedly connected to the corresponding positions of the lifting base 202. The lifting hydraulic cylinders 203 drive the lifting base 202 to rise and fall vertically relative to the fixed base 201. A clamping assembly 204 is provided circumferentially at the through hole of the lifting seat 202. The telescopic end of the clamping assembly 204 is radially pressed against the outer wall of the rotary cutting sleeve 4 to achieve fixed clamping. The rotating assembly 205 drives the clamping assembly 204 to rotate along the vertical central axis of the rotary cutting sleeve 4.

[0035] The full-rotation drilling rig 2 is the core cutting equipment. The fixed base 201 is placed on the roadbed plate 1. On the construction site, it can be reinforced and fixed by using a counterweight fork or ground anchor to avoid horizontal displacement and shaking of the machine body when the drilling rig is cutting hard rock.

[0036] Large-sized through holes are reserved in the middle of the fixed seat 201 and the lifting seat 202. The inner diameter of the through holes is larger than the design diameter of the pile foundation, which facilitates clamping and adjustment. The lifting hydraulic cylinders 203 arranged at the four corners adopt a synchronous hydraulic control method, with uniform extension and retraction stroke, ensuring that the lifting seat 202 always remains in a horizontal state and preventing the rotary cutting sleeve 4 from being skewed and worn.

[0037] The clamping assembly 204 inside the lifting seat 202 adopts a hydraulic chuck structure. Referring to the clamping principle of a lathe, multiple sets of hydraulic top blocks evenly press against the outer wall of the sleeve from the radial direction, resulting in uniform clamping force and reducing the risk of damaging the sleeve shell. The rotating assembly 205 adopts a gear meshing drive method. The reduction motor drives the drive gear to rotate, which, together with the large-diameter gear ring, drives the entire clamping assembly 204 to rotate. This provides high transmission torque, a durable structure, and suitability for high-load working conditions in hard rock cutting.

[0038] In the preferred embodiment, the cable wedge assembly 5 includes a wedge block 501, a hanging plate 502, and a tension cable 503; One end of the traction cable 503 is fixedly connected to the hanging plate 502, and the other end is fixedly connected to the wedge block 501; Multiple sets of tension cables 503, together with corresponding wedges 501, are arranged around the circumference of the hanging plate 502, and the lengths of each set of tension cables 503 are different, so that all wedges 501 form a staggered arrangement structure with different heights and different circumferential angles in space. A tension sensor 7 is also provided at the connection between the traction cable 503 and the hanging platform 502 to collect tension data in real time during the traction operation. The outer diameter of the hanging plate 502 is smaller than the inner diameter of the central hole 3; The top of the hoisting plate 502 is connected to the output end of the winch 8. The winch 8 drives the hoisting plate 502 to move vertically back and forth through the winding and pulling action, which in turn drives the traction cable 503 to drive the wedge block 501 to complete the vertical jerking disturbance action.

[0039] The tension cable 503 is made of high-strength galvanized alloy steel, which has high tensile strength, is not easy to bend or break, and can withstand repeated jerking and radial inertial forces. The wedge 501 is made of high-manganese wear-resistant alloy steel with a hardened surface treatment, making it harder than ordinary hard rock and less prone to wear and deformation under long-term compression and impact. The tension cables 503 have different lengths, allowing the wedges 501 to be spatially staggered to fit irregular rock crevices and increase the probability of interlocking.

[0040] The tension sensor 7 is installed at the connection point between the tension cable 503 and the hoisting platform 502. This location receives the force directly without stress loss, resulting in more accurate tension data. The outer diameter of the hoisting platform 502 is smaller than that of the central hole 3, preventing it from scraping against the hole wall during lowering. The winch 8 is directly connected to the hoisting platform 502 via a wire rope, achieving vertical reciprocating motion through rapid winding and unwinding. This design is simple, has a low failure rate, and is suitable for harsh outdoor construction environments.

[0041] In the preferred embodiment, the rotary cutting sleeve 4 is a hollow straight cylinder structure, and several cutting edges 401 are uniformly fixed circumferentially at its lower end; The top of the rotary cutting sleeve 4 is provided with several lifting lugs 402. The lifting lugs 402 are connected to the matching hanger 6 by steel wire rope. The hanger 6 is connected to the hoisting equipment to realize vertical hoisting. The top of the cable wedge assembly 5 is equipped with a hook 504, which is detachably fixed to the hanger 6 by a steel wire rope, so that the rotary cutting sleeve 4 and the cable wedge assembly 5 can be lifted and transported synchronously by relying on the same hanger 6.

[0042] The rotary cutting casing 4 is a hollow, high-strength cylinder, entirely constructed of thickened alloy steel, offering strong resistance to extrusion deformation. The lower cutting edge 401 is inlaid with a carbide tip, exhibiting high hardness and high-temperature resistance, preventing dulling and chipping during continuous cutting of hard rock. At least three lifting lugs 402 are installed at the top of the casing, evenly distributed circumferentially. Insufficient lugs can lead to uneven lifting stress and deformation at the top of the casing; multiple lugs disperse lifting stress, ensuring stable vertical lifting of the casing. The lifting frame 6 serves as a universal lifting carrier, connecting the casing to the cable wedge assembly 5. The hook 504 uses a detachable connection, facilitating easy assembly and disassembly without affecting the normal movement of the drilling rig. The entire lifting structure is highly versatile, eliminating the need for customized specialized lifting equipment and adapting to conventional construction site lifting machinery, thus reducing equipment operating costs.

[0043] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A method for constructing ring-hole pile foundations in hard rock strata, characterized in that: The method includes: S1. Level and compact the pile foundation construction site, complete the pile position coordinate measurement and layout according to the design drawings, and accurately determine the center point of the pile foundation and the borehole outline range. S2. Lay roadbed plates (1) in the pile position area after the layout is completed, hoist the full-rotation drilling rig (2) to the roadbed plate (1) and position it, adjust the position of the full-rotation drilling rig (2) and correct the verticality of the whole machine. S3. A central hole is formed by vertically drilling at the center point of the pile foundation (3). S4. The rotary cutting sleeve (4) is fitted outside the central hole (3). The rotary cutting sleeve (4) is driven to rotate continuously by the full-rotation drilling rig (2). At the same time, the axial feed of the rotary cutting sleeve (4) is controlled to press down, and the hard rock strata are cut in a segmented ring-shaped drilling and cutting manner, so that the rock mass is broken into multiple independent rock blocks after being ring-cut. S5. The cable wedge assembly (5) is placed into the central hole (3) using hoisting equipment and lowered to the height range of the rock block (4) to be cut in this segment; S6. The cable wedge assembly (5) of the traction equipment performs a vertical, jerky reciprocating traction action, causing several wedges (501) on the assembly to be thrown out radially and wedge into the gaps of the fractured rock blocks to form a mechanical self-locking mechanism. S7. Control the full-rotation drilling rig (2) to release the clamp on the rotary cutting sleeve (4). The rotary cutting sleeve (4) and the cable wedge assembly (5) are hoisted synchronously. After the rock block segment is brought out of the pile foundation hole as a whole, the locking of the cable wedge assembly (5) is released to complete the unloading of the rock block. S8. Lift the rotary cutting sleeve (4) back into the pile foundation hole and repeat steps S4-S7 until all segment pile foundation drilling operations are completed.

2. The method for constructing ring-hole pile foundations in hard rock formations according to claim 1, characterized in that: In step S3, a small independent drilling device is used to vertically drill and form a central hole (3). The diameter of the central hole (3) is 1 / 6 to 1 / 5 of the inner diameter of the rotary cutting sleeve (4), and the diameter is not less than 100 mm. It is used to provide an inner free space for the ring cutting and fragmentation of hard rock strata.

3. The method for constructing ring-hole pile foundations in hard rock formations according to claim 1, characterized in that: In step S4, the full-rotation drilling rig (2) drives the rotary cutting casing (4) to rotate at a constant speed and at the same time controls the rotary cutting casing (4) to feed axially at a low constant speed, and adopts a segmented feeding method to carry out ring drilling. The segmented feed length is set to 0.8-1.2 times the inner diameter of the rotary cutting sleeve (4). After each segment is fed, the axial feed is paused and the rotary cutting sleeve (4) is kept rotating so that the hard rock mass fractures along the circumferential surface to a suitable fracture height.

4. The method for constructing ring-hole pile foundations in hard rock strata according to claim 3, characterized in that: In step S4, when the rotary cutting sleeve (4) completes the axial segmented feeding and maintains rotation, the vertical jerking reciprocating pulling action of the cable wedge assembly (5) is started, so that the wedge block (501) of the cable wedge assembly (5) is thrown out radially and wedges into the gap just formed by the rock block in that section, so as to achieve the matching coordination between the timing of the wedge block (501) being thrown out and wedged into and the timing of rock mass fracturing.

5. The method for constructing ring-hole pile foundations in hard rock strata according to claim 3, characterized in that: The vertical pausing reciprocating traction action adopts a constant high frequency small amplitude reciprocating mode, and the single traction stroke is 1 / 10-1 / 8 of the inner diameter of the rotary cutting sleeve (4).

6. The method for constructing ring-hole pile foundations in hard rock formations according to claim 3, characterized in that: During the traction operation, the data on the tension fluctuation of the traction equipment is collected in real time. When the amplitude of the tension fluctuation continues to narrow and remains stable at the preset pause cycle, it is determined that the wedge (501) and the rock block gap form an effective engagement, and then the pause traction action is terminated.

7. The method for constructing ring-hole pile foundations in hard rock strata according to claim 1, characterized in that: In step S7, the hoisting plate (502) of the cable wedge assembly (5) is fixedly connected to the matching hanger (6) of the rotary cutting sleeve (4), and the two are simultaneously lifted and transported the rock block inside the rotary cutting sleeve (4); After the rotary cutting sleeve (4) is lifted and removed from the pile foundation hole, the drive cable wedge assembly (5) generates vibration disturbance, breaks the clamping and limiting structure between the rock blocks and between the rock blocks and the inner wall of the sleeve, and allows the rock blocks to be removed from the rotary cutting sleeve (4) to complete the unloading operation.

8. The construction apparatus for a method of constructing a ring borehole for pile foundations in hard rock strata according to claim 1, characterized in that: The full-rotation drilling rig (2) includes a fixed base (201) and a lifting base (202), with the fixed base (201) fixed to the top surface of the roadbed plate (1); The roadbed plate (1), the fixing seat (201) and the lifting seat (202) are provided with through holes that are coaxial with the center of the pile foundation, and the inner diameter of the through holes is larger than the design size of the pile foundation hole. Lifting hydraulic cylinders (203) are vertically arranged at the four corners of the fixed base (201). The telescopic ends of the lifting hydraulic cylinders (203) are fixedly connected to the corresponding positions of the lifting base (202). The lifting hydraulic cylinders (203) drive the lifting base (202) to lift vertically relative to the fixed base (201). The lifting seat (202) is provided with a clamping component (204) in the circumferential direction at the through hole. The telescopic end of the clamping component (204) is radially pressed against the outer wall of the rotary cutting sleeve (4) to achieve fixed clamping. The rotating component (205) drives the clamping component (204) to rotate along the vertical central axis of the rotary cutting sleeve (4).

9. The construction apparatus for a method of constructing a ring borehole for pile foundations in hard rock strata according to claim 1, characterized in that: The cable wedge assembly (5) includes a wedge block (501), a hanging plate (502), and a tension cable (503); One end of the traction cable (503) is fixedly connected to the hanging plate (502), and the other end is fixedly connected to the wedge block (501); Multiple sets of tension cables (503) together with corresponding wedges (501) are arranged around the circumference of the hanging plate (502), and the lengths of each set of tension cables (503) are different, so that all wedges (501) form a staggered arrangement structure with different heights and different circumferential angles in space; A tension sensor (7) is also provided at the connection between the traction cable (503) and the hanging platform (502) to collect tension data in real time during the traction operation. The outer diameter of the hanging plate (502) is smaller than the inner diameter of the central hole (3); The top of the hoist (502) is connected to the output end of the winch (8). The winch (8) drives the hoist (502) to move vertically back and forth through the winding and pulling action, thereby driving the traction cable (503) to drive the wedge (501) to complete the vertical jerking and disturbance action.

10. The construction apparatus for a method of constructing a ring borehole for pile foundations in hard rock strata according to claim 1, characterized in that: The rotary cutting sleeve (4) is a hollow straight cylinder structure, with several cutting edges (401) evenly fixed at its lower end. The top of the rotary cutting sleeve (4) is provided with several lifting lugs (402). The lifting lugs (402) are connected to the matching hanger (6) by steel wire rope. The hanger (6) is connected to the hoisting equipment to realize vertical hoisting. The cable wedge assembly (5) is equipped with a hook (504) at the top. The hook (504) is detachably fixed to the hanger (6) by a wire rope, so that the rotary cutting sleeve (4) and the cable wedge assembly (5) can be lifted and transported synchronously by relying on the same hanger (6).

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