Hollow pile bottom grouting device and pile bottom grouting method

Abstract

The present invention provides a grouting device and a grouting method for the bottom of a hollow pile. The bottom of the hollow pile is connected to a bottom plate, a transmission joint is rotatably installed on the bottom plate, a grouting device is threadedly connected to the transmission joint, the grouting device is screwed downward to below the bottom plate by rotating the transmission joint, and a grouting channel is provided in the grouting device; the top of the transmission joint is used to connect with a grouting pipe movable in the hollow pile. The present invention can effectively improve the bearing capacity of the hollow pile through grouting at the bottom of the pile, thereby improving the safety of the project and saving materials and project capital investment; the grouting pipe is used as a grouting tool and can be reused on the one hand, and at the same time, it is also used as a driving component for driving the grouting device to penetrate the soil layer, which has multiple uses, and does not need to use other tools to move the grouting device downward, thereby improving the grouting efficiency.

Description

Technical Field

[0001] The invention relates to building pile foundation construction, and in particular to a pile bottom grouting system based on a hollow pile and a pile bottom grouting method thereof. Background Art

[0002] Hollow piles are mainly divided into two categories: precast concrete piles and precast steel piles. Hollow piles can withstand large loads, have reliable pile body quality, fast construction speed, and economical engineering cost. They are one of the widely used pile types in pile foundation engineering. Hollow piles are widely used in engineering due to factors such as small construction impact and mature pile making technology. Commonly used hollow piles are precast concrete pipe piles and steel pipe piles.

[0003] At present, the commonly used hollow piles in China generally do not have pre-buried grouting pipes in the pile body. During the application process, it is often difficult to fully exert the bearing capacity of the pile body due to construction or soil layer reasons, resulting in the phenomenon that the bearing capacity of a single pile is far lower than the bearing capacity of the pile body. The main reason is that the soil layer strength on the pile side and pile end is insufficient, which cannot provide sufficient pile side friction resistance and pile end resistance. Therefore, the grouting technology of the pile side and pile end of the hollow pile has gradually begun to develop. However, the current hollow pile post-grouting technology is difficult to promote and apply on a large scale due to the complex design, difficult construction, and high implementation cost.

[0004] Chinese patent application number 201810340103.0 discloses a post-grouting pile head and a post-grouting construction method. Through a mechanical structure, the front end of the pile head is displaced due to the grouting pressure, and cement slurry is injected into the soil through the grouting hole at the pile head, thereby completing the post-grouting construction of the pile end. The shortcomings of this invention are: 1. The structure of the pre-grouting end of this technology is relatively complicated, and it is necessary to open a hole in the pre-grouting end. Conventional processing methods cannot be used for processing, and special processing molds are required. The processing difficulty is relatively high, and the processing accuracy control is difficult; 2. There is no grouting pipe docking device, and the upper grouting pipe must be followed up at the beginning of pile driving. When the pipe pile is connected, the grouting pipe needs to be connected synchronously, which affects the efficiency of pile driving construction and the grouting pipe cannot be recycled, and the use cost is high; 3. The grouting hole lacks a reliable hole blocking protection structure, and hole blocking is very likely to occur during pile driving, resulting in grouting failure.

[0005] Chinese patent application number 200720029134.1 discloses a grouting pile head with a certain distance between the bottom pile head and the pile end. Cement slurry is injected into the soil through the middle grouting pipe to form a grouting body. The shortcomings of this invention are as follows: 1. There is no grouting pipe docking device. The upper grouting pipe must be followed up with the construction at the beginning of pile driving. The grouting pipe needs to be connected synchronously when the pile is connected, which affects the efficiency of pile driving construction and the grouting pipe cannot be recycled; 2. There is no slurry check structure. After the grouting is completed and the grouting plug pressure is released, the injected slurry is easy to flow back from the soil to the inside of the PHC pile, and the grouting reinforcement effect is poor; 3. The grouting outlet is located on the side of the pile end, and it is difficult for the slurry to flow to the pile end, and it is difficult to achieve effective reinforcement of the pile bottom soil.

[0006] In summary, the conventional grouting devices currently have the disadvantages of complex structure, lack of grouting pipe docking device, difficulty in grouting pipe docking, lack of reliable grouting hole protection structure, poor grouting reinforcement effect, high implementation cost, and high requirements for implementation control. The hollow pile grouting pile heads currently used in the market have more or less one or more of these disadvantages. Therefore, there is a lack of a grouting device and method that integrates the advantages of simple processing, convenient docking, convenient construction, fast construction, not easy to block pipes, not easy to block grouting holes, and no slurry backflow. Summary of the invention

[0007] The purpose of the present invention is to propose a new grouting device and method for grouting the bottom of a hollow pile based on the shortcomings of the above-mentioned technology. A transmission joint is rotatably installed on the pile bottom plate, and a grouting device that can be swung out is threadedly connected inside the transmission joint. After the movable grouting pipe in the hollow pile is connected to the transmission joint, the grouting pipe drives the transmission joint to rotate so that the grouting device that can be swung out penetrates the soil layer for grouting. In order to achieve the above-mentioned technical effects, the technical scheme adopted by the present invention is as follows:

[0008] A grouting device for a hollow pile whose bottom can be rotated out, wherein the bottom of the hollow pile is connected to a bottom plate,

[0009] A transmission butt joint is rotatably mounted on the bottom plate, and the rotatable grouting device is rotatably mounted below the bottom plate by rotating the transmission butt joint, and the rotatable grouting device is threadedly connected to the inside of the transmission butt joint, and a grouting channel is arranged inside the rotatable grouting device;

[0010] The top end of the transmission joint is used to be connected to the grouting pipe in the hollow pile.

[0011] Furthermore, the grouting pipe is axially lifted and lowered in the hollow pile;

[0012] The bottom of the grouting pipe is detachably connected to the top of the transmission butt joint, and the grouting pipe and the transmission butt joint are relatively fixed after being connected in place.

[0013] Furthermore, the grouting pipe is connected to the top end of the transmission joint by means of a threaded connection, a mechanical snap or a necked joint.

[0014] Furthermore, if the grouting pipe is connected to the transmission joint through a threaded connection, a rotation limiting device is provided on the grouting pipe or the transmission joint.

[0015] Furthermore, a one-way valve is provided in the transmission joint or the rotatable grouting device.

[0016] Furthermore, after the transmission butt joint is connected to the base plate, the transmission butt joint can rotate circumferentially but cannot move axially.

[0017] Furthermore, the base plate is provided with a first hole, and an upper connecting slot located outside the first hole is welded or mechanically connected to the upper surface of the base plate, and a connecting socket embedded in the upper connecting slot is provided at the bottom of the transmission docking joint.

[0018] Furthermore, the transmission joint is rotatably mounted on the base plate via a rolling bearing.

[0019] Furthermore, a pile tip is installed on the lower surface of the bottom plate, and a second hole coaxial with the first hole is provided at the bottom of the pile tip;

[0020] The inner side wall of the second hole is provided with a guide mechanism which is slidably matched with the rotatable grouting device, and the rotation of the transmission docking joint drives the rotatable grouting device to axially extend outward from the second hole.

[0021] Furthermore, the rotatable grouting device is provided with a rigid tube, and the inner space of the rigid tube serves as the grouting channel.

[0022] The middle side wall of the rigid tube is provided with a limit baffle protruding outward, and the diameter of the limit baffle is larger than the bottom hole diameter of the second hole;

[0023] The upper side wall of the rigid tube is provided with an external thread which cooperates with the inner wall thread of the transmission joint, and the lower side wall of the rigid tube is provided with at least one grouting hole. The lower end face of the rigid tube is provided with a protective end, and the second hole is sealed by the protective end during the pile driving stage.

[0024] Further, the guide mechanism is at least one guide notch circumferentially arranged on the inner diameter of the second hole;

[0025] A circumferential rigid guide wing is provided on the lower side wall of the rigid tube, and the rigid guide wing is axially slidably matched with the guide slot.

[0026] Furthermore, a grouting bag structure communicating with the grouting hole is provided at the bottom of the rigid pipe.

[0027] Furthermore, a protective device is provided on the top of the transmission joint.

[0028] A pile bottom grouting method using the above-mentioned grouting device with a rotatable bottom of the hollow pile, the pile bottom grouting method is as follows:

[0029] S1, constructing the hollow pile to a preset depth, the transmission butt joint is installed on the bottom plate of the hollow pile, and the rotatable grouting device is connected to the transmission butt joint;

[0030] S2, lowering the grouting pipe through the middle cavity of the hollow pile and docking it with the transmission butt joint, and the grouting pipe and the transmission butt joint are relatively fixed after being connected in place;

[0031] S3, the grouting pipe drives the transmission joint to rotate, so that the rotatable grouting device moves axially downward and penetrates into the soil layer at the pile end;

[0032] S4, the slurry in the grouting pipe is continuously injected into the grouting channel and flows out to the surrounding reference soil;

[0033] S5, after the pile bottom grouting is completed, the grouting is stopped, and the connection between the grouting pipe and the transmission joint is released;

[0034] S6. Take out the grouting pipe from the middle cavity of the hollow pile and continue the grouting construction of the next pile.

[0035] Since the present invention adopts the above technical solution, its advantages are:

[0036] 1) Grouting at the bottom of the pile can effectively improve the bearing capacity of the hollow pile, thereby improving the safety of the project and saving materials and project capital investment;

[0037] 2) The transmission butt joint, the rotatable grouting device and the hollow pile are pressed into the soil together. The grouting pipe lowered in the pile drives the transmission butt joint to make the rotatable grouting device penetrate into the soil layer for grouting. Grouting at the bottom of the pile does not affect the construction of the hollow pile. Grouting can be carried out after the pile pressing construction is completed, thereby improving the construction efficiency of the hollow pile.

[0038] 3) The grouting pipe is a grouting tool that can be reused, saving materials and reducing engineering capital investment. At the same time, the grouting pipe is also used as a driving component for driving the swivellable grouting device to penetrate the soil layer. It has multiple uses and does not require the use of other tools to move the swivellable grouting device downward;

[0039] 4) A one-way valve can be installed in the transmission joint or the rotatable grouting device to prevent slurry backflow, improve the grouting effect, and save grouting materials;

[0040] 5) The structural design is highly reliable and easy to implement, which is conducive to large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0042] Figure 1 This is a schematic structural diagram of the swivellable grouting device provided by the present invention in the first embodiment of the present invention in the initial state;

[0043] Figure 2 This is a state diagram of a rotatable grouting device in a rotatable grouting device extending downward in the first embodiment of the present invention;

[0044] Figure 3 It is a side view of the transmission butt joint in the first embodiment of the present invention;

[0045] Figure 4 It is a three-dimensional diagram of a transmission butt joint in the first embodiment of the present invention;

[0046] Figure 5 It is a side view of a grouting device that can be rotated out in the first embodiment of the present invention;

[0047] Figure 6 It is a three-dimensional diagram of a grouting device that can be rotated out in the first embodiment of the present invention;

[0048] Figure 7 It is a three-dimensional diagram of the bottom plate in the first embodiment of the present invention;

[0049] Figure 8 It is a side view of the bottom plate in the first embodiment of the present invention;

[0050] Fig. 9 It is a side view of the pile tip in the first embodiment of the present invention;

[0051] Fig.10 It is a three-dimensional diagram of the pile tip in the first embodiment of the present invention;

[0052] Fig.11 This is a schematic structural diagram of the swivellable grouting device in the initial state in the second embodiment of the present invention;

[0053] Fig.12 This is a schematic diagram of a transmission butt joint connected to a base plate via a bearing in a second embodiment of the present invention;

[0054] Fig.13This is a schematic diagram of a grouting pipe and a transmission joint being connected by threads in Embodiment 3 of the present invention;

[0055] Fig.14 This is a schematic diagram of an embodiment 3 of the present invention, in which an internal thread is provided on the top of the transmission butt joint;

[0056] Fig.15 This is a schematic diagram of a swivellable grouting device provided by the present invention in Embodiment 4 of the present invention;

[0057] Fig.16 It is a schematic diagram of the bag grouting bag structure after it is expanded in the fourth embodiment of the present invention;

[0058] Fig.17 It is a side view of a transmission butt joint in the fourth embodiment of the present invention;

[0059] Fig.18 It is a three-dimensional diagram of a transmission butt joint in the fourth embodiment of the present invention;

[0060] Fig.19 This is a schematic diagram of the rotatable grouting device provided by the present invention in Example 5 of the present invention.

[0061] Description of reference numerals:

[0062] Grouting pipe 1; transmission joint 2; butt connection part 2.1; internal thread 2.2; connection bayonet 2.3; screwable grouting device 3; rigid pipe 3.1; external thread 3.2; one-way valve 3.3; limit baffle 3.4; grouting hole 3.5; rigid guide wing 3.6; protection end 3.7; bag structure 3.8; bottom plate 4; upper connection slot 4.1; first hole 4.2; pile tip 5; second hole 5.1; guide slot 5.2. Hollow pile 6. DETAILED DESCRIPTION

[0063] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0064] In order to fully understand the present invention, detailed steps and detailed structures will be proposed in the following description to illustrate the technical solution of the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0065] The present invention provides a grouting device for a hollow pile with a rotatable bottom, wherein a bottom plate 4 is connected to the bottom of the hollow pile 6. The bottom plate 4 can be made of a steel plate and fixed to the lower end surface of the hollow pile 6 by welding.

[0066] A transmission butt joint 2 is rotatably installed on the base plate 4, and a rotatable grouting device 3 is threadedly connected to the transmission butt joint 2. A grouting channel is provided in the rotatable grouting device 3. The rotatable grouting device 3 is axially moved to the lower surface of the base plate 4 by rotating the transmission butt joint 2; a butt connection part 2.1 is provided at the top end of the transmission butt joint 2 for connecting with the grouting pipe 1 in the hollow pile 6.

[0067] The advantages of the present invention using a liftable grouting pipe 1 are: (1) Since the pile driving construction needs to be implemented in multiple sections, the fixed grouting pipe must be connected when the piles in different sections are connected, which affects the efficiency of the pile driving construction. The grouting pipe can be lowered from the pile hole for grouting after all the pile driving is completed; (2) The grouting pipe can be reused, and a fixed grouting pipe needs to be installed for each pile, which saves grouting pipe materials; (3) The grouting pipe can be lowered for grouting after the pile driving construction, avoiding the risk of damaging the grouting pipe during the pile driving construction, and the grouting success rate is more reliable. Embodiment 1

[0068] Reference Figure 1-Figure 10 As shown, the grouting device of the embodiment of the present invention includes a device and a specific grouting method that can be used for grouting at the bottom of a hollow pile, wherein the grouting device includes a grouting pipe 1, a transmission joint 2, a rotatable grouting device 3, a base plate 4, a pile tip 5, and a hollow pile 6.

[0069] The grouting pipe 1 is fixed by connecting the thread with the thread of the transmission butt joint 2, and the grouting pipe 1 drives the transmission butt joint 2 to rotate.

[0070] The transmission joint 2 and the base plate 4 are non-fixedly connected so that the transmission joint 3 can rotate but cannot move. The method is as follows: an upper connecting slot 4.1 is welded on the upper surface of the base plate 4 so that the bottom connecting bayonet 2.3 of the transmission joint is embedded in the upper connecting slot 4.1.

[0071] The swivelable grouting device 3 adopts a segmented rigid tube 3.1, and the upper section of the rigid tube 3.1 is provided with an external thread 3.2 for matching with the internal thread of the transmission butt joint 2. The position of the swivelable grouting device 3 is controlled by rotating the transmission butt joint 2, so that the swivelable grouting device 3 is swivelable downward. The lower section of the rigid tube 3.1 is densely covered with grouting holes 3.5, so that the slurry in the grouting channel can flow out.

[0072] The lower surface of the bottom plate 4 is connected to the upper surface of the pile tip 5 to form the outer shell of the grouting device. The lower end of the pile tip 5 is provided with a second hole 5.1 with a diameter between the outer diameter of the rigid tube 3.1 and the outer diameter of the limit baffle 3.4. The second hole 5.1 is provided with two guide notches 5.2 in the diameter direction that are consistent with the rigid guide wings 3.6, so that the rotatable grouting device 3 can only move vertically in the second hole 5.1 of the pile tip 5.

[0073] The lower section of the rigid tube 3.1 is also provided with axial rigid guide wings 3.6, which are respectively inserted into the guide slots 5.2 to prevent the rotation of the swivelable grouting device 3. A limit baffle 3.4 having a diameter larger than the second hole 5.1 is provided in the middle of the rigid tube 3.1 to prevent the swivelable grouting device 3 from extending too far from the second hole 5.1 after rotation, so as to cause the swivelable grouting device 3 to be separated from the transmission docking head 2.

[0074] A one-way valve 3.3 is provided inside the swivellable grouting device 3 to ensure that the slurry can only flow from the rigid tube 3.1 to the grouting hole 3.5 in one direction and cannot flow in the opposite direction, thereby preventing the slurry from flowing back after the grouting stops and saving the slurry. A conical protective end 3.7 is provided on the lower end surface of the swivellable grouting device 3, and the outer edge of the protective end 3.7 can cover the second hole 5.1 and the guide notch 5.2 provided on the pile tip 5, thereby ensuring the sealing effect of the pile tip 5 during the pile pressing process and preventing soil from entering the grouting channel of the swivellable grouting device 3.

[0075] The pile tip 5 can have various structures, including but not limited to cone, flat head, spindle, etc. In special cases, the pile head structure can be directly cancelled, and the main structure can be connected only through the end steel plate and the inside of the hollow pile.

[0076] The specific implementation process of using this device for hollow pile bottom grouting is as follows:

[0077] The transmission butt joint 2, the screw-out grouting device 3, the bottom plate 4, and the pile tip 5 are connected and assembled. The bottom plate 4 and the pile tip 5 are welded, and the upper connecting groove 4.1 is welded on the bottom plate 4 near the pile pipe side so that the connecting bayonet 2.3 on the transmission butt joint 2 can be inserted into the upper connecting groove 4.1. The screw-out grouting device 3 is inserted from the second hole 5.1, and the transmission butt joint 2 is rotated so that the protective end 3.7 of the screw-out grouting device 3 is closely attached to the pile tip 5 and connected to the transmission butt joint 2 by thread.

[0078] The bottom plate 4 is connected to the bottom of the hollow pile 6 by welding, and conventional pile driving operation is carried out. After the pile foundation is constructed to the designed depth, the grouting pipe 1 is inserted into the middle cavity of the hollow pile 6. The grouting pipe 1 contacts the transmission joint 2 through the conical structure, and the grouting pipe 1 is rotated to make it tightly connected with the transmission joint 2.

[0079] The grouting pipe 1 is continuously rotated, driving the transmission joint 2 to rotate and push out the grouting device 3 through the thread, and the protective end 3.7 of the grouting device penetrates into the soil at the pile end and exposes the grouting hole 3.5.

[0080] Connect the grouting pipe to the grouting equipment and carry out grouting operation until the grouting is completed.

[0081] After the grouting operation is completed, the grouting pipe 1 is rotated in the reverse direction to disengage it from the transmission joint 2, and the grouting pipe 1 is recovered to complete the rear grouting work. Embodiment 2

[0082] Reference Figure 11-Figure 12 As shown, the second embodiment is similar to the first embodiment, and the main difference is that the connection mode between the bottom plate 4 and the transmission butt joint 2 has been changed, and the original upper connection slot 4.1 has been changed into a bearing-type structure, and the bottom plate 4 and the transmission butt joint 2 are rotatably connected by a rolling bearing 2.4. After the bearing-type connection is adopted, the transmission butt joint 2 and the bottom plate 4 can be directly connected by bearing welding, without the need for secondary processing, which can simplify the construction process and reduce the time of on-site processing. At the same time, the bearing connection has a small rotation resistance and the connection is more reliable. Embodiment 3

[0083] Reference Figure 13-14 As shown, Example 3 is similar to Example 1, and the main difference is that the grouting pipe 1 is changed from the original internal thread type to an external thread setting, and the thread 2.2 at the upper part of the transmission joint 2 below and the grouting pipe is also changed from the original external thread to an internal thread setting, and a partition plug 1.1 is provided above the end of the grouting pipe 1 as a rotation limit device to prevent the grouting pipe 1 from being rotated into place and its thread cannot drive the transmission joint 2 to continue rotating due to the lack of a locking mechanism.

[0084] The use of externally threaded grouting pipes is mainly to increase the application scenarios of actual on-site construction and to meet the construction scenarios of different types of grouting pipes. Embodiment 4

[0085] Reference Figure 15-18 As shown, the fourth embodiment is similar to the first embodiment, and the main difference from the first embodiment is that its end grouting device adopts a bladder grouting structure. As shown in the figure, a grouting bladder structure 3.8 is provided at the lower section of the rigid pipe 3.1, and the internal cavity of the grouting bladder structure 3.8 is connected to the grouting hole 3.5.

[0086] After the rotatable grouting device is pressed into the soil, the grouting is injected into the grouting bag structure 3.8. The grouting bag structure 3.8 is filled with slurry and expands, which can effectively control the shape and volume of the grouting. The grouting is completed after the designed grouting amount is reached.

[0087] The main purpose of this embodiment is also to increase the applicability of grouting for different formation conditions and improve the grouting effect for different formation conditions. Embodiment 5

[0088] Reference Fig.19As shown, the fifth embodiment is similar to the first embodiment, and the main difference from the first embodiment is that in order to prevent debris from falling from the upper part of the hollow pile, a raising platform 7 is added below to raise the height of the transmission butt joint 2, a certain space is reserved on both sides of the transmission butt joint 2 to store the debris falling from the upper part, and a protective device 8 is set on the top of the transmission butt joint 2. The protective device 8 can be made of, but not limited to, paper or plastic protective film, flip cover, etc., to prevent debris from falling onto the threads on the transmission butt joint during the pile pressing process, causing the butt joint to fail. The protective device 8 does not affect the grouting under the pressure of grouting.

[0089] The main purpose of this embodiment is to add the function of protecting the transmission joint thread, to prevent the transmission joint thread from failing due to debris falling into the hole during the pile driving process, and to improve the success rate of grouting implementation.

[0090] The above describes the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and the devices and structures that are not described in detail should be understood to be implemented in a common manner in the art; any technician familiar with the art can use the above-disclosed methods and technical contents to make many possible changes and modifications to the technical solutions of the present invention without departing from the scope of the technical solutions of the present invention, or modify them into equivalent embodiments of equivalent changes, which does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention are still within the scope of protection of the technical solutions of the present invention.

Claims

1. A grouting device for a hollow pile with a rotatable bottom, wherein the bottom of the hollow pile (6) is connected to a bottom plate (4), characterized in that: A transmission butt joint (2) is rotatably mounted on the bottom plate (4); after the transmission butt joint (2) is connected to the bottom plate (4), the transmission butt joint (2) can rotate circumferentially but cannot move axially; a rotatable grouting device (3) is internally threadedly connected to the transmission butt joint (2); the rotatable grouting device (3) is rotatably mounted below the bottom plate (4); a grouting channel is provided in the rotatable grouting device (3); the rotatable grouting device (3) is provided with a rigid tube (3.1); the internal space of the rigid tube (3.1) serves as the grouting channel; at least one grouting hole (3.5) is provided on the lower side wall of the rigid tube (3.1); and a protective end (3.7) is provided on the lower end surface of the rigid tube (3.1); The top end of the transmission joint (2) is used to be connected to the grouting pipe (1) in the hollow pile (6); The bottom plate (4) is provided with a first hole (4.2), a pile tip (5) is installed on the lower surface of the bottom plate (4), and a second hole (5.1) coaxial with the first hole (4.2) is provided at the bottom of the pile tip (5); The inner wall of the second hole (5.1) is provided with a guide mechanism that slidably cooperates with the rotatable grouting device (3), and the rotation of the transmission joint (2) drives the rotatable grouting device (3) to move out of the second hole ( 5.1) extending axially outward, the guide mechanism being at least one guide notch (5.2) circumferentially arranged on the inner diameter of the second hole (5.1); A circumferential rigid guide wing (3.6) is provided on the lower side wall of the rigid tube (3.1), and the rigid guide wing (3.6) is axially slidably matched with the guide notch (5.2).

2. The grouting device for a hollow pile with a rotatable bottom as claimed in claim 1, characterized in that: The grouting pipe (1) is axially lifted and lowered in the hollow pile (6); The bottom of the grouting pipe (1) is detachably connected to the top of the transmission butt joint (2), and the grouting pipe (1) and the transmission butt joint (2) are relatively fixed after being connected in place.

3. The grouting device for a hollow pile with a rotatable bottom as claimed in claim 2, characterized in that: The grouting pipe (1) is connected to the top end of the transmission joint (2) by means of a threaded connection, a mechanical buckle or a necked joint.

4. The grouting device for a hollow pile with a rotatable bottom as claimed in claim 3, characterized in that: A rotation limiting device is provided on the grouting pipe (1) or the transmission joint (2).

5. The grouting device for a hollow pile with a rotatable bottom as claimed in claim 1, characterized in that: A one-way valve (3.3) is provided in the transmission butt joint (2) or the rotatable grouting device (3).

6. The grouting device for a hollow pile with a rotatable bottom as claimed in claim 1, characterized in that: An upper connection slot (4.1) located outside the first hole (4.2) is welded or mechanically connected to the upper surface of the bottom plate (4), and a connection slot (2.3) embedded in the upper connection slot (4.1) is provided at the bottom of the transmission docking joint (2).

7. The grouting device for a hollow pile with a rotatable bottom as claimed in claim 5, characterized in that: The transmission joint (2) is rotatably mounted on the base plate (4) via a rolling bearing (2.4).

8. The grouting device for a hollow pile with a rotatable bottom as claimed in claim 1, characterized in that: A middle side wall of the rigid tube (3.1) is provided with a limit baffle (3.4) protruding outwards, and the diameter of the limit baffle (3.4) is larger than the bottom hole diameter of the second hole (5.1); The upper side wall of the rigid tube (3.1) is provided with an external thread (3.2) which cooperates with the internal thread of the transmission joint (2), and the second hole (5.1) is sealed by the protective end (3.7) during the pile pressing stage.

9. The grouting device for a hollow pile with a rotatable bottom as claimed in claim 1, characterized in that: A grouting bag structure (3.8) communicating with the grouting hole (3.5) is provided at the bottom of the rigid pipe (3.1).

10. The grouting device for a hollow pile with a rotatable bottom as claimed in claim 1, characterized in that: A protective device (8) is provided on the top of the transmission butt joint (2).

11. A pile bottom grouting method using the grouting device with a rotatable bottom of a hollow pile as claimed in any one of claims 1 to 10, characterized in that: The pile bottom grouting method is as follows: S1, constructing the hollow pile (6) to a preset depth, the transmission butt joint (2) being installed on the bottom plate (4) of the hollow pile (6), and the rotatable grouting device (3) being connected inside the transmission butt joint (2); S2, lowering the grouting pipe (1) through the middle cavity of the hollow pile (6) and docking it with the transmission butt joint (2), and the grouting pipe (1) and the transmission butt joint (2) are relatively fixed after being connected in place; S3, the grouting pipe (1) drives the transmission joint (2) to rotate, so that the rotatable grouting device (3) moves axially downward and penetrates into the soil layer at the pile end; S4, the slurry in the grouting pipe (1) is continuously injected into the grouting channel and flows out to the surrounding soil; S5, after the pile bottom grouting is completed, the grouting is stopped, and the connection between the grouting pipe (1) and the transmission joint (2) is released; S6, taking out the grouting pipe (1) from the hollow pile (6), and continuing the grouting construction of the next pile.

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