A fully weathered granite cast-in-place pile hole forming device and construction method

Abstract

The application discloses a full-weathered granite bored pile hole-forming device and a construction method, and relates to the field of bored pile hole-forming devices.The bored pile hole-forming device comprises a guide assembly, a drill bit assembly, a fixed rotating assembly, a propelling assembly and an outer protection assembly.The guide assembly of the hole-forming device is connected with the fixed rotating assembly, the drill bit assembly is connected with the propelling assembly, and the fixed rotating assembly is provided with a clamping device and a locking device.The propelling assembly is connected with a power arm, and the power arm provides propelling and rotating power for the whole hole-forming device.The hole-forming device is characterized in that the hole-forming drill bit and the fracturing tube are arranged along a central ring in an interval manner.In the process of forming a bored pile hole, the hole is formed in the full-weathered granite stratum and the carbon dioxide fracturing tube is filled, the hole-forming process and the fracturing tube installation process of the fracturing tube filling hole are integrated through rotating switching, the bored pile hole-forming construction in the relatively hard stratum, such as the full-weathered granite stratum, is realized quickly, the accurate drilling positioning blasting guarantees the quality of the bored pile hole-forming, and the accurate blasting of the full-weathered granite stratum is realized.

Description

Technical Field

[0001] This invention relates to cast-in-place piles in the fields of building and geotechnical construction, and more particularly to a drilling device and construction method for cast-in-place piles made of completely weathered granite. Background Technology

[0002] With the development of urban construction and the accelerated pace of infrastructure construction such as railway bridges, pile foundations have been increasingly widely used. However, due to complex engineering geological environments and shortcomings in construction technology, problems such as poor pile foundation construction quality and heavy construction pollution are inevitable. Therefore, quality assurance and environmental protection in construction are facing increasing challenges. Traditional driven piles are increasingly criticized for their environmental impact and difficulty in adapting to complex geological formations. Meanwhile, bored piles, with their low pollution, no soil displacement, no noise, no vibration, and excellent construction results, have become an important alternative to driven piles in some fields.

[0003] Due to varying geological histories and different strata distributions across regions, drilling methods for cast-in-place piles in soft soil foundations have become relatively mature, with rotary drilling being the most representative example. However, when drilling in hard strata such as completely weathered granite, using traditional rotary drill bits presents several challenges. Firstly, the drill bits lack sufficient strength, resulting in significant wear during drilling. Secondly, the limited power provided by the construction machinery to the rotary drill bits makes it difficult to overcome the drilling resistance of hard rock strata, leading to slow drilling speeds or even failure to drill at all. Consequently, construction efficiency is low, construction costs are high, and the desired drilling results cannot be achieved.

[0004] Currently, the construction of cast-in-place piles in hard strata still faces significant technical challenges. Existing blasting methods for hard rock formations primarily employ explosive blasting, but explosive blasting excavation carries certain safety hazards and can easily cause injuries. In actual engineering projects, large chunks of rock often emerge after explosive detonation, and the blasting and splitting processes generate a large amount of debris, making it difficult to control the blast surface. Furthermore, the smoke and dust generated after explosive blasting pose challenges to environmental pollution control.

[0005] Carbon dioxide fracturing technology is a novel rock fracturing technique with high explosive power, high safety, low environmental pollution, and the ability to achieve precise blasting, thus showing great application potential. However, the installation of carbon dioxide fracturing is relatively cumbersome and the construction efficiency is low. Therefore, how to provide a new device and apply it to the construction of cast-in-place piles that can both ensure the precise positioning of blasting for cast-in-place piles in hard strata and simplify the construction steps and accelerate the construction speed has become an urgent technical problem to be solved. Summary of the Invention

[0006] Purpose of the invention: The purpose of this invention is to provide a drilling device and construction method for cast-in-place piles made of completely weathered granite, so as to solve the technical problem that existing technologies are unable to achieve efficient drilling of cast-in-place piles in relatively hard rock strata in different formations.

[0007] Technical solution: The present invention provides a drilling device for fully weathered granite cast-in-place piles, comprising a guiding assembly, a drill bit assembly, a fixed rotating assembly, a propulsion assembly, and an external protection assembly.

[0008] The fixed rotating assembly includes an outer rotating ring and an inner rotating ring, on which are distributed snap-fit ​​units and advance holes; the snap-fit ​​unit has a clamping hole for the fracturing tube, and a locking device for locking the fracturing tube is provided in the clamping hole; a clamping device for fixing the drill bit assembly is provided on the side of the snap-fit ​​unit.

[0009] The guiding assembly includes a first rotating ring, a second rotating ring, a drill bit guide tube, and a storage tube for the fracturing tube; the guiding assembly is connected to the fixed rotating assembly through the storage tube for the fracturing tube; the propulsion assembly is connected to the drill bit assembly, and the propulsion assembly drives the guiding assembly, drill bit assembly, fixed rotating assembly, and propulsion assembly to rotate synchronously under the action of the power arm; one end of the storage tube extends and is connected to the snap-fit ​​unit, and the top end of the fracturing tube enters the fracturing tube clamping hole and is locked or released by the locking device.

[0010] The base plate of the outer protective assembly has multiple openings corresponding to the storage pipe of the fracturing tube or the drill bit of the drill bit assembly.

[0011] The locking device includes a horizontal latch, a spring, a locking assembly, and a fracturing tube filling assembly; the locking assembly includes a latch at the top of the fracturing tube, which pushes the horizontal latch to both sides during the jacking process, and the horizontal latch is reset under the action of the spring.

[0012] The fracturing tube burial assembly includes a push rod motor and a vertical clamping plate. The push rod motor drives the horizontal clamping plate to move and burial the fracturing tube.

[0013] The drill bit assembly includes an outer ring drill bit base, an inner ring drill bit base, and a drill bit. The outer ring drill bit base and the inner ring drill bit base have grooves on their edges to accommodate the fracturing tube storage tube.

[0014] The clamping device includes a support plate, an electric telescopic rod, and a slide rail. The electric telescopic rod drives the support plate to extend outward along the normal direction of the snap-fit ​​unit to clamp the outer ring drill bit base.

[0015] The propulsion assembly includes an outer base, an inner base, and a push rod, which passes through a propulsion hole and connects to the outer ring drill bit base and the inner ring drill bit base.

[0016] The first rotating ring includes a first inner ring and a first outer ring, and the second rotating ring includes a second inner ring and a second outer ring. The first inner ring, the second inner ring, the first outer ring and the second outer ring are provided with multiple guide holes for passing through a drill bit or a fracturing tube.

[0017] The outer protective assembly also includes a top plate and side walls. The top plate has a through hole through which the push rod passes, and a rolling bearing is provided between the top plate and the side walls.

[0018] The construction method of the drilling device for cast-in-place piles of completely weathered granite of the present invention includes the following steps:

[0019] (1) Level the site and locate the pile positions. The pile position deviation should be ≤30mm.

[0020] (2) Install steel casings and check the verticality of the steel casings. The steel casings should be buried at a depth of 1-1.5m.

[0021] (3) Use a rotary drilling rig to drill holes in soft strata. Adjust the rotary drilling rig to the pile position and adjust the verticality of the drill bit to ensure that the verticality deviation is ≤1%.

[0022] (4) Start the rotary drilling machine to form a hole. After the drilling machine has drilled to the set depth for a single drilling operation, the drill bit stops working and is lifted up to dump the soil.

[0023] (5) Conduct pile location verification and hole inspection to ensure pile hole deviation or hole quality;

[0024] (6) Repeat steps (4) and (5). When the rotary drilling rig encounters a completely weathered granite stratum, stop working, lift the rotary drilling rig upwards, and move it out of the pile hole.

[0025] (7) Fill the fracturing tube with carbon dioxide gas, align the storage tube of the fracturing tube with the opening of the bottom plate of the outer protective component, and inspect the electrode of the fracturing tube; then lay the drilling device flat, push the fracturing tube into the storage tube of the fracturing tube through the opening guide tube of the bottom plate of the outer protective component, lock the fracturing tube with the locking device in the clamping hole at the top of the fracturing tube, and use on-site machinery to install the drilling device with the fracturing tube installed at the drill bit position of the drilling rig.

[0026] (8) Position the drilling device and align it with the pile hole, ensuring that the verticality deviation is ≤1%.

[0027] (9) Start the construction machinery, put the hole-forming device into the pile hole, monitor the bottom of the pile hole with a searchlight and camera, and stop descending when the bottom guide pipe of the outer protective component touches the bottom of the pile hole.

[0028] (10) Rotate the hole-forming device to make the drill bit align with the base plate to open the hole. The process is as follows: start the clamping device to fix the outer ring drill bit base and the inner ring drill bit base. At the same time, the power arm controls the outer base to rotate 30 degrees and the inner base to rotate 60 degrees in the propulsion assembly, driving the drill bit assembly to rotate 30 degrees on the outer ring and 60 degrees on the inner ring. After that, the inner ring and outer ring drill bits align with the base plate to open the hole.

[0029] (11) Start the propulsion assembly and drill motor. The drill bit extends out of the bottom plate opening through the drill bit guide and drills downward. When the drilling depth reaches the preset depth, stop drilling. The propulsion assembly lifts and drives the drill bit back into the bottom plate opening.

[0030] (12) Conduct a hole quality inspection of the drill bit. After the hole is qualified, start the propulsion component to control the hole-forming device to rotate 30° on the outer ring and 60° on the inner ring. At this time, the pipe opening of the fracture storage tube is aligned with the opening of the bottom plate of the outer protection component, and the opening of the bottom plate is aligned with the hole drilled by the drill bit.

[0031] (13) The fracturing pipe is buried, specifically, the locking device is started, the push rod motor is started and the vertical clamping plate is pushed to both sides, the vertical clamping plate drives the horizontal buckle to move to both sides, the horizontal buckle is released, and the fracturing pipe is placed into the borehole; after the fracturing pipe is placed, the hole-forming device is lifted upward and moved out of the pile hole.

[0032] (14) Use fine sand to fill the borehole tightly, and cover the opening of the pile hole with a blasting bag;

[0033] (15) The electrode at the top of the fracturing tube is excited by a wireless remote control device. The electrode is excited to high temperature, which vaporizes liquid carbon dioxide gas and breaks the rock strata around the fracturing tube.

[0034] (16) After detonation, use a crane to grab and clean the broken rock layers and fracture tubes, and carry out hole cleaning and inspection;

[0035] (17) Repeat steps (7) to (16) until the hole depth of the cast-in-place pile reaches the design depth.

[0036] In step (13), a one-way fracturing tube is placed in the outer hole, and a two-way fracturing tube is placed in the other holes.

[0037] Working principle: Carbon dioxide fracturing technology has the advantages of high blasting power, low pollution, and controllable blasting surface. Carbon dioxide fracturing technology uses high pressure to convert gaseous carbon dioxide into liquid, which is then injected into the carbon dioxide fracturing tube. When the excited microcurrent passes through the heat-conducting rod, the generated high temperature breaks through the safety membrane, causing the liquid carbon dioxide to instantly vaporize. This produces a huge amount of expanding gas that rushes towards the rock strata, achieving the effect of fracturing the rock.

[0038] In this invention, the drilling bit and fracturing tube of the hole-forming device are arranged at intervals along the central ring. This invention uses a rotary drilling rig for hole formation in soft strata and carbon dioxide fracturing technology for blasting hole formation in completely weathered granite strata. When drilling for cast-in-place piles, this invention drills holes and fills them with carbon dioxide fracturing tubes in completely weathered granite strata. By rotating and switching, the drilling process of filling the hole with fracturing tubes and the installation process of fracturing tubes are integrated, which can quickly realize the construction of cast-in-place pile holes in relatively hard strata such as completely weathered granite strata. At the same time, the precise drilling positioning and blasting ensure the quality of the cast-in-place pile hole formation and realizes precise blasting in completely weathered granite strata. While ensuring the quality of hole formation, the hole formation speed is accelerated.

[0039] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0040] (1) The present invention applies carbon dioxide fracturing technology to the construction device to form the grouting pile hole forming device of the present invention. The hole forming device adopts carbon dioxide fracturing technology, which converts gaseous carbon dioxide into liquid through high pressure and injects it into the carbon dioxide fracturing tube. For soft strata, rotary drilling rig is used to form holes, and for harder strata, such as completely weathered granite strata, carbon dioxide fracturing blasting is used to form holes. It can cope with the hole forming and excavation of complex strata conditions, realize efficient hole forming of grouting piles and has a wider range of applications.

[0041] (2) The present invention’s grouting pile drilling device simultaneously achieves drilling in completely weathered granite rock layers and installing fracturing tubes in the holes for blasting, thus accelerating the construction speed.

[0042] (3) The drilling and installation process of traditional fracturing tubes is relatively cumbersome. In the drilling device of the present invention, the filling of fracturing tubes is convenient and quick. In addition, the protection of the fracturing tube by the fracturing tube storage tube can reduce the disturbance of the fracturing tube by the drill bit.

[0043] (4) A searchlight and a camera are installed on the base plate of the outer protective component, which can be used to investigate and locate the specific conditions of the working face at the bottom of the borehole.

[0044] (5) The drilling bit and the fracturing tube of the hole-forming device of the present invention are arranged at intervals along the central ring. By rotating and switching, the drilling process of filling the hole with the fracturing tube and the installation process of the fracturing tube are integrated, which quickly realizes the construction of the hole-forming of cast-in-place piles in relatively hard strata such as completely weathered granite strata. At the same time, the precise drilling positioning blasting ensures the quality of the hole-forming of cast-in-place piles.

[0045] (6) The method for constructing cast-in-place piles of the present invention designs and fixes the drilling according to the designed blasting hole position. The drill bit guide ensures the verticality and stability of the drill bit. The drill bit drills synchronously during drilling, the drilling position is accurate, the blasting surface can be precisely controlled, and the construction process is safer and more environmentally friendly. Attached Figure Description

[0046] Figure 1 This is a structural diagram of the main body of the bored pile drilling device of the present invention;

[0047] Figure 2 This is a general drawing of the bored pile drilling device of the present invention;

[0048] Figure 3 This is a perspective view of the bored pile drilling device of the present invention;

[0049] Figure 4 This is a structural diagram of the guide assembly of the bored pile drilling device of the present invention;

[0050] Figure 5 A schematic diagram of the drill bit assembly of the present invention;

[0051] Figure 6 This is a schematic diagram of the fixed rotating assembly of the present invention;

[0052] Figure 7 This is a planar schematic diagram of the propulsion component of the present invention;

[0053] Figure 8 This is a schematic diagram of the drill bit assembly structure of the present invention;

[0054] Figure 9 This is a schematic diagram of the external protective component of the present invention;

[0055] in, Figure 9 (a) is a schematic diagram of the base plate of the external protective assembly. Figure 9 (b) is a schematic diagram of the sidewall of the outer protective component;

[0056] Figure 10 This is a side view of the outer protective component of the present invention;

[0057] Figure 11 This is a diagram showing the bolt connection between the base plate of the outer protective component and the side wall of the outer protective component according to the present invention;

[0058] Figure 12 Schematic diagram of a locking device installed for a cracked pipe;

[0059] in, Figure 12 (a) is a side view. Figure 12 (b) is a top view;

[0060] Figure 13 This is a schematic diagram of the snap-fit ​​unit of the present invention;

[0061] in, Figure 13 (a) is a schematic diagram of the clamping device after it has retracted. Figure 13 (b) is a schematic diagram of the extended clamping device. Figure 13 (c) is a partial schematic diagram of the clamping device;

[0062] Figure 14 This is a simplified diagram of the internal structure of the snap-fit ​​unit of the present invention;

[0063] in, Figure 14 (a) Front view Figure 14 (b) is a top view;

[0064] Figure 15 This is a structural diagram of the top plate of the outer protective component of the present invention;

[0065] in, Figure 15 (a) is a plan view of the top plate of the external protective assembly. Figure 15 (b) is a vertical cross-sectional view of AA;

[0066] Figure 16 This is a construction drawing of the grouting pile drilling device of the present invention. Detailed Implementation

[0067] like Figures 1 to 10 As shown, the drilling device for fully weathered granite cast-in-place piles of the present invention includes a guiding component a, a drill bit component b, a fixed rotating component c, a propulsion component d, and an outer protective component. The outer protective component serves to protect the internal space of the inner structure. During operation, a gap is maintained between the outer protective component and the internal structure to ensure that the internal structure has room to rotate.

[0068] like Figure 1 As shown, the guide assembly a of the bored pile drilling device of the present invention is connected to the fixed rotating assembly c through the fracturing tube storage pipe 3. The propulsion assembly d is connected to the drill bit assembly b through the push rod 14, and the upper part of the propulsion assembly d is connected to the power arm, which provides rotational and propulsion power to the propulsion assembly d.

[0069] like Figure 4 As shown, the guide assembly a includes a fixing ring assembly and a conduit assembly. The conduit assembly includes a drill bit guide 1 and a storage tube 3 for the fracturing tube 32. This guide assembly a serves two purposes: firstly, by connecting the drill bit guide 1, the first rotating ring 2, and the second rotating ring 4 into a single unit and passing through the guide hole 5, it guides the drill bit 8 and prevents it from deviating during construction and movement. Secondly, by connecting the drill bit guide 1, the first rotating ring 2, the second rotating ring 4, and the fracturing tube storage tube 3 into a single unit and passing through the fracturing tube storage hole 7, it stores the carbon dioxide fracturing tube 3.

[0070] Both the first rotating ring 2 and the second rotating ring 4 include an inner ring and an outer ring. In this embodiment, the outer ring has 12 guide holes on its outer edge, and the inner ring has 6 guide holes on its outer edge and 1 guide hole at its center. The guide holes are for the passage of the drill bit 8 and the fracturing tube 32. In this invention, a rolling bearing is provided between the inner ring and the outer ring, allowing the inner and outer rings to rotate around the ring center.

[0071] like Figure 5As shown, drill bit assembly b includes drill bit 8, outer ring drill bit base 9, and inner ring drill bit base 10, wherein the position of drill bit 8 corresponds to the position of guide hole 5 in guide assembly a. Six drill bits are evenly arranged on the outer edge of the outer ring drill bit base 9, with adjacent outer edge drill bits positioned at a 60-degree angle relative to the ring center. One drill bit is arranged at the center of the inner ring drill bit base 10, and three drill bits are evenly arranged on its outer edge, with adjacent outer edge drill bits positioned at a 120-degree angle relative to the ring center. Motors are installed within the inner and outer ring drill bit bases to provide rotational power for the drill bits. In this invention, a gap is left between the outer ring drill bit base 9 and the inner ring drill bit base 10, allowing rotation along the center of the base.

[0072] like Figure 3 , Figure 6 As shown, the snap-fit ​​unit 15 in the fixed rotating assembly c is connected to the fracturing tube storage tube 3 in the guide assembly a on one hand, and is used to arrange the clamping device 18 and the locking device 31 on the other hand. That is, one end of the storage tube 3 extends and is connected to the snap-fit ​​unit 15; the top end of the fracturing tube 32 enters the fracturing tube clamping hole 20 and is locked or released by the locking device 31.

[0073] like Figure 14 As shown, the clamping device 18 is an electrically retractable device, equipped with a switch for remote control of its extension and retraction. A row of clamping devices 18 is arranged on each of the upper and lower sides of the fracture clamping hole 20, with four electrically retractable push rods 18-2 in each row. The electrically retractable push rods 18-2 are fixedly connected to the clamping devices. The extension and retraction of the clamping devices 18 is achieved by electrically controlling the extension and retraction of the electrically retractable push rods 18-2. The slide rail 18-3 is used to keep the clamping devices 18 from deviating from the track during extension and retraction. Before operation, the clamping devices 18 are retracted into the latching unit 15.

[0074] like Figure 13 As shown in Figure (a), taking the outer ring drill bit base 9 as an example, when the propulsion assembly d drives the drill bit assembly b to a position close to the outer rotating ring 17 and the inner rotating ring 19, the operator activates the control switch. At this time, the clamping device 18 extends outward along the normal direction on both sides of the latching unit, as shown in Figure (a). Figure 13 As shown in Figure (b), on the one hand, when the clamping device 18 extends outward, it clamps the outer ring drill bit base 9 of the drill bit assembly b, ensuring its position is fixed; on the other hand, the clamping device support plate 18-1 blocks the front end of the outer ring drill bit base 9 to prevent it from slipping off, as shown in Figure (b). Figure 13 As shown in Figure (c).

[0075] Since the guide assembly a and the fixed rotating assembly c are connected, and the drill bit assembly b and the feed assembly d are connected, the drill bit assembly b and the fixed rotating assembly c are clamped and fixed by the clamping device 18. When the feed assembly d rotates, it drives the guide assembly a, the drill bit assembly b, and the fixed rotating assembly c to rotate synchronously. The fracturing tube is pushed into the fracturing tube storage tube 3 from the guide hole adjacent to the drill bit 8 on the bottom side of the guide assembly through the opening 22 of the bottom plate of the outer protective assembly. The top end of the fracturing tube is locked by the locking device 31 arranged in the clamping hole 20. In this invention, a rolling bearing is provided between the inner and outer rotating rings, which can rotate along the center of the rotating ring.

[0076] like Figure 7 , Figure 8 As shown, the propulsion assembly d includes an outer base 11, an inner base 12, and a push rod 14. The push rod 14 passes through the propulsion hole 16 and connects to the inner and outer drill bit bases, transmitting forward thrust to the drill bit 8 during operation. In this invention, a rolling bearing is provided between the inner and outer bases, allowing rotation around the center of the base.

[0077] like Figure 3 , Figure 5 , Figure 8 As shown, drill bit assembly b and propulsion assembly d are connected as a whole by push rod 14 and outer ring drill bit base 9 and inner ring drill bit base 10. In this invention, grooves are provided on the edges of outer ring drill bit base 9 and inner ring drill bit base 10, and the other end of storage tube 3 passes through the groove, so that the inner and outer ring drill bit bases are offset from the position of fracturing tube storage tube 3 and slide axially. The size of the groove is larger than that of fracturing tube storage tube.

[0078] like Figure 2 , Figure 9 , Figure 10 , Figure 15 As shown, the outer protective assembly includes a base plate 25, a top plate 43, and sidewalls 26, used to maintain the internal space. The base plate 25 has 10 guide holes 22, 3 cameras 23, and 3 searchlights 21. The cameras 23 and searchlights 21 are used to detect the bottom of the hole. A guide tube 22-1 is connected to the base plate opening 22, serving two purposes: firstly, to guide the drill bit 8 during drilling, ensuring its verticality and stability; and secondly, to provide fixation by pressing against the bottom of the pile hole. During operation, the base plate openings 22 correspond to the positions of the drill bit 8 or the fracturing tube storage hole 7, with the drill bit 8 and fracturing tube storage pipe 3 arranged sequentially in a ring. The top plate 43 of the outer protective assembly has a through hole 39 through which the push rod 14 passes. Through the rolling bearings 42 between the outer top plate 40, the inner top plate 41 and the side wall 26 of the outer protective assembly, the push rod 14 rotates along the center of the top plate, which will drive the inner and outer top plates and the internal ring assemblies to rotate along the center of the ring.

[0079] like Figure 9 , Figure 11As shown, in this invention, the outer protective component base plate 25 and the outer protective component side wall 26 are provided with three bolt holes 24, and each hole is designed with two rows of four high-strength bolts 30.

[0080] like Figure 6 , Figure 12 As shown, the locking device 31 is located in the clamping hole 20 at the top of the fracturing tube. Before the drilling device operates, when loading the fracturing tube, the fracturing tube storage hole 7 and the bottom plate opening 22 are first aligned on the same central axis. Then, the top of the fracturing tube is pushed forward through the bottom plate opening guide tube 22-1, passing through the bottom plate opening 22 to reach the fracturing tube storage tube 3. During the pushing process, the top-end buckle 33 of the fracturing tube pushes the horizontal buckle 34 to both sides. When the top-end buckle 33 of the fracturing tube slides past the horizontal buckle 34, the spring 36 returns the horizontal buckle 34 to its original position, locking the top-end buckle 33 of the fracturing tube, thus achieving the locking process of the fracturing tube 32. After the drilling device drills a hole with the drill bit 8, the vertical clamping plate 38 is pushed by controlling the push rod motor 35 to extend and retract. The vertical clamping plate 38 drives the horizontal buckle 34 to move to both sides, realizing the process of releasing and burying the carbon dioxide fracturing tube 32. The vertical buckle 37 is used to restrict the position of the horizontal buckle 34.

[0081] like Figure 14 As shown, the construction method of the hole-forming device for cast-in-place piles of completely weathered granite of the present invention is as follows:

[0082] (1) Level and clean the site, locate the pile positions, and ensure that the pile position deviation is ≤30mm;

[0083] (2) Install steel casing, check the verticality of the steel casing, and depending on the site conditions, the casing should be buried at a depth of 1-1.5m and the casing should be 30cm above the ground.

[0084] (3) First, a continuous rotary drilling rig is used to drill holes in soft strata. The rotary drilling rig is positioned, the rotary drill bit is adjusted to the pile position, and the verticality of the drill bit is adjusted to ensure that the verticality deviation is ≤1%.

[0085] (4) Start the drilling excavator and drill downwards to form a hole. During construction, observe the verticality of the hole and the quality of the hole at all times. After the drilling machine has drilled to the set depth for a single drilling operation, the drill bit stops working and is lifted upwards to dump the soil.

[0086] (5) Conduct pile location verification and hole inspection to ensure that pile hole deviation or hole quality meets the specifications.

[0087] (6) Repeat construction steps (4) and (5). When the rotary drilling reaches a certain depth, the continuous rotary drilling rig stops working when it encounters a completely weathered granite stratum. The rotary drilling rig is then lifted upwards and removed from the pile hole.

[0088] (7) Gas filling of the carbon dioxide fracturing tube. Before use, align the position of the fracturing tube storage tube 3 with the opening 22 of the bottom plate of the outer protective component, and check the fracturing tube electrode and the hole forming device of the present invention. After the check is correct, fill the carbon dioxide fracturing tube. Then, lay the hole forming device flat, push the fracturing tube 32 into the fracturing tube storage tube 3 through the bottom plate opening guide tube 22-1 of the outer protective component, and fix the fracturing tube 32 by the locking device 31 in the clamping hole 20 at the top of the fracturing tube. Use on-site machinery to install the hole forming device of the present invention with the fracturing tube installed at the drill bit position of the drilling rig.

[0089] (8) Position the drilling device and align it with the pile hole, ensuring that the verticality deviation is ≤1%;

[0090] (9) Start the construction machinery, put the hole-forming device into the pile hole, monitor the bottom of the hole with the searchlight 21 and camera 23, and stop descending when the bottom plate opening guide 22-1 of the outer protective component touches the bottom of the pile hole.

[0091] (10) Since the opening 22 of the outer protective component base plate corresponds to the fracturing tube storage hole 7 when installing the fracturing tube, the internal structure of the starting device is rotated and adjusted so that the drill bit 8 is aligned with the opening 22 of the base plate. As mentioned above, six drill bits 8 are evenly arranged on the outer edge of the outer ring drill bit base 9, and the positions of adjacent drill bits are distributed at 60 degrees relative to the center of the ring. Three drill bits are evenly arranged on the outer edge of the inner ring drill bit base, and the positions of adjacent drill bits are distributed at 120 degrees relative to the center of the ring. The drill bits 8 and the fracturing tube storage tube 3 are evenly spaced, and the angle between the drill bits 8 of the outer ring and the fracturing tube hole is 30 degrees, while the angle between the drill bits 8 of the inner ring and the fracturing tube hole is 60 degrees. The clamping device 18 is activated to fix the outer ring drill bit base 9 and the inner ring drill bit base 10 respectively. At the same time, the upper power arm controls the outer base 11 and the inner base 12 in the propulsion assembly d to rotate 30 degrees and 60 degrees respectively, driving the entire device, including the drill bit assembly b, to rotate 30 degrees and 60 degrees on the outer ring and the inner ring respectively. At this time, the positions of the inner and outer ring drill bits 8 are aligned with the bottom plate opening 22.

[0092] (11) Start the propulsion assembly d and the drill motor. The drill bit 8 extends out of the bottom plate opening 22 through the drill bit guide tube 1 and drills downward. In this embodiment, the set depth for a single drilling is 0.8m. When the drilling depth reaches the preset depth, drilling stops. The propulsion assembly d lifts and drives the drill bit 8 back into the bottom plate opening 22.

[0093] (12) Conduct a hole quality inspection of drill bit 8. After the hole is qualified, start the propulsion component d control device structure to rotate 30° on the outer ring and 60° on the inner ring. At this time, the opening of the fracture storage pipe 3 is aligned with the opening 22 of the bottom plate of the outer protection component, and the opening 22 of the bottom plate is aligned with the hole drilled by drill bit 8.

[0094] (13) To install the carbon dioxide fracturing tube, the operator activates the locking device 31, the push rod motor 35 starts, and pushes the vertical clamping plate 38 to both sides. The vertical clamping plate 38 drives the horizontal buckle 34 to move to both sides, the buckle is released, and the fracturing tube is installed into the drilled hole. Preferably, to ensure the fracturing effect, a unidirectional fracturing tube is installed in the outermost hole with the vent hole facing inward, and bidirectional fracturing tubes are installed in the remaining holes. No fracturing tubes are installed in the holes in the center. After the fracturing tube is installed, the drilling device is lifted upward and removed from the pile hole.

[0095] (14) Use fine sand to fill the borehole tightly, and cover the opening of the borehole with a blasting cloth.

[0096] (15) The electrode at the top of the fracturing tube is excited by a wireless remote control device. The electrode is excited to high temperature, which causes the liquid carbon dioxide gas to be rapidly vaporized and the rock strata around the fracturing tube to be broken.

[0097] (16) After detonation, wait for the smoke and dust to dissipate, use a grab crane to grab and clean the broken rock layers and fractured pipes, and clean and inspect the holes.

[0098] (17) Repeat the above construction steps (7) to (16) until the hole depth reaches the design depth.

Claims

1. A drilling device for cast-in-place piles made of completely weathered granite, characterized in that: It includes a guide assembly (a), a drill bit assembly (b), a fixed rotating assembly (c), a propulsion assembly (d), and an outer protection assembly; The fixed rotating assembly (c) includes an outer rotating ring (17) and an inner rotating ring (19); the outer rotating ring (17) and the inner rotating ring (19) are provided with snap-fit ​​units (15) and push holes (16); the snap-fit ​​unit (15) is provided with a clamping hole (20) for the fracturing tube, and a locking device (31) for locking the fracturing tube is provided in the clamping hole (20); the snap-fit ​​unit (15) is provided with a clamping device (18) for fixing the drill bit assembly (b) on its side. The guiding assembly (a) includes a first rotating ring (2), a second rotating ring (4), a drill bit guide tube (1), and a storage tube (3) for the fracturing tube (32); the guiding assembly is connected to the fixed rotating assembly (c) through the storage tube (3) of the fracturing tube (32); the propulsion assembly (d) is connected to the drill bit assembly (b), and the propulsion assembly (d) drives the guiding assembly (a), the drill bit assembly (b), the fixed rotating assembly (c), and the propulsion assembly (d) to rotate synchronously under the action of the power arm; The base plate (25) of the outer protective assembly has multiple openings (22) corresponding to the storage pipe (3) of the fracturing tube (32) or the drill bit (8) of the drill bit assembly (b). The drill bit assembly (b) includes an outer ring drill bit base (9), an inner ring drill bit base (10), and a drill bit (8). The outer ring drill bit base (9) and the inner ring drill bit base (10) are provided with grooves on their edges to accommodate the fracturing tube storage tube. The clamping device (18) includes a support plate (18-1), an electric telescopic rod (18-2), and a slide rail (18-3). The electric telescopic rod (18-2) drives the support plate to extend outward along the normal direction of the buckling unit (15) to clamp the outer ring drill bit base (9) and the inner ring drill bit base (10). The propulsion assembly (d) includes an outer base (11), an inner base (12), and a push rod (14), which passes through a propulsion hole (16) and is connected to the outer ring drill bit base (9) and the inner ring drill bit base (10). The first rotating ring (2) includes a first inner ring and a first outer ring, and the second rotating ring (4) includes a second inner ring and a second outer ring. The first inner ring, the second inner ring, the first outer ring and the second outer ring are provided with multiple guide holes for passing through a drill bit (8) or a fracturing tube (32).

2. The drilling device for cast-in-place piles of completely weathered granite according to claim 1, characterized in that: The locking device (31) includes a horizontal buckle (34), a spring (36), a locking assembly, and a fracturing tube filling assembly; the locking assembly includes a fracturing tube top buckle (33), which pushes the horizontal buckle (34) to both sides during the jacking process, and the horizontal buckle (34) is reset under the action of the spring (36).

3. The drilling device for cast-in-place piles of completely weathered granite according to claim 2, characterized in that: The fracturing tube burial assembly includes a push rod motor (35) and a vertical clamping plate (38). The push rod motor (35) drives the horizontal clamp (34) to move through the vertical clamping plate (38) to burial the fracturing tube (32).

4. The drilling device for cast-in-place piles of completely weathered granite according to claim 3, characterized in that: The outer protective assembly also includes a top plate (43) and a side wall (26). The top plate (43) has a through hole (39) through which the push rod (14) passes, and a rolling bearing is provided between the top plate and the side wall.

5. A construction method for a hole-forming device for cast-in-place piles of completely weathered granite as described in claim 4, characterized in that: Includes the following steps: (1) Level the site and locate the pile positions. The pile position deviation should be ≤30mm. (2) Install steel casings and check the verticality of the steel casings. The steel casings should be buried at a depth of 1-1.5m. (3) Use a rotary drilling rig to drill holes in soft strata. Adjust the rotary drilling rig to the pile position and adjust the verticality of the drill bit to ensure that the verticality deviation is ≤1%; (4) Start the rotary drilling machine to form a hole. After the drilling machine has drilled to the set depth for a single drilling operation, the drill bit stops working and is lifted up to dump the soil. (5) Conduct pile location verification and hole inspection to ensure the quality of pile hole formation; (6) Repeat steps (4) and (5). When the rotary drilling rig encounters a completely weathered granite stratum, stop working, lift the rotary drilling rig upwards, and move it out of the pile hole; (7) Fill the fracturing tube with carbon dioxide gas, align the storage tube (3) of the fracturing tube with the opening (22) of the bottom plate of the outer protective component, and inspect the fracturing tube electrode; then push the fracturing tube into the storage tube (3) of the fracturing tube through the bottom plate opening guide (22-1) of the outer protective component, lock the fracturing tube (32) through the locking device (31) in the clamping hole (20) at the top of the fracturing tube, and install the hole-forming device with the fracturing tube installed at the drill bit position of the drilling rig; (8) Position the drilling device and align it with the pile hole, ensuring that the verticality deviation is ≤1%; (9) Start the construction machinery, put the hole-forming device into the pile hole, monitor the bottom of the pile hole with a searchlight and camera, and stop descending when the bottom plate of the outer protective component opening guide (22-1) touches the bottom of the pile hole; (10) Rotate the hole-forming device to align the drill bit (8) with the hole opening (22) on the base plate. The process is as follows: Start the clamping device (18) to fix the outer ring drill bit base (9) and the inner ring drill bit base (10). At the same time, the power arm controls the outer base (11) in the propulsion assembly to rotate 30 degrees and the inner base (12) to rotate 60 degrees, driving the drill bit assembly to rotate 30 degrees on the outer ring and 60 degrees on the inner ring. After that, the inner ring and outer ring drill bits are aligned with the hole opening (22) on the base plate. (11) Start the propulsion assembly and drill motor. The drill bit (8) extends out of the bottom plate opening (22) through the drill bit guide tube (1) and drills downward. When the drilling depth reaches the preset depth, stop drilling. The propulsion assembly lifts and drives the drill bit back into the bottom plate opening (22). (12) Conduct a hole quality inspection of the drill bit (8). After the hole is qualified, start the propulsion component (d) to control the hole-forming device to rotate 30° on the outer ring and 60° on the inner ring. At this time, the pipe opening of the fracture storage pipe (3) is aligned with the bottom plate opening (22) of the outer protection component, and the bottom plate opening (22) is aligned with the hole drilled by the drill bit. (13) The fracturing pipe is buried, specifically, the locking device (31) is started, the push rod motor (35) is started and the vertical clamping plate (38) is pushed to both sides. The vertical clamping plate drives the horizontal buckle (34) to move to both sides. The horizontal buckle is released and the fracturing pipe is placed into the borehole. After the fracturing pipe is placed, the hole-forming device is lifted upward and moved out of the pile hole. (14) Use fine sand to fill the borehole tightly, and cover the opening of the pile hole with a blasting bag; (15) The electrode at the top of the fracturing tube is excited by a wireless remote control device. The electrode is excited to high temperature, which vaporizes the liquid carbon dioxide gas and breaks the rock strata around the fracturing tube. (16) After detonation, use a crane to grab and clean the broken rock layers and fracture tube, and clean and inspect the hole; (17) Repeat steps (7) to (16) until the hole depth of the cast-in-place pile reaches the design depth.

6. The construction method of the hole-forming device for completely weathered granite cast-in-place piles according to claim 5, characterized in that: In step (13), a one-way fracturing tube is placed in the outer hole, and a two-way fracturing tube is placed in the other holes.

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