Construction method of stiff pipe pile adopting double-wall steel pipe device for hole guiding

Abstract

The invention discloses a construction method of a stiff pipe pile adopting a double-wall steel pipe device to guide a hole, which comprises the following steps: at a set position, driving the double-wall steel pipe device to drill a pile hole by using a pile machine, clamping the pile machine on an outer steel pipe to drive the double-wall steel pipe device to rotate and sink when the pile hole is drilled, and meanwhile, spraying cement paste outwards through an outer paste spraying nozzle, cement paste and underground soil are mixed to form a cement soil annular structure; when the double-wall steel pipe device sinks to a set height, the hollow prestressed pipe pile sinks into the annular cavity; the inner steel pipe is pulled out upwards, so that the soil body in the inner steel pipe is reserved underground; and the outer steel pipe is upwards rotated and pulled out, cement paste is synchronously sprayed outwards, the cement soil annular structure is stirred, and the cement soil stirring pile is formed. The annular cavity of the double-wall steel pipe device is used for sinking the hollow prestressed pipe pile, the coaxiality of the cement-soil mixing pile and the hollow prestressed pipe pile is guaranteed, meanwhile, due to the fact that holes do not need to be cleaned in the annular cavity, the construction efficiency is improved, and the soil squeezing effect is reduced.

Description

Technical Field

[0001] The invention relates to a construction method of a rigid pipe pile using a double-wall steel pipe device to guide a hole. Background Art

[0002] Rigid composite pile is a new type of pile foundation. The realization of rigid composite pile is first to form cement soil pile, and then to press concrete core pile into place, thus forming a new pile type in which concrete core pile and cement soil work together to bear the upper load. Rigid composite pile has the characteristics of friction pile because the pile-soil squeeze-expansion interface is enlarged, the load transfer path is improved, and the cement soil pile has much higher lateral resistance than concrete pile, while the concrete core pile has much higher pile body strength than cement soil pile. The combination of the two can obtain a higher cost-effectiveness than traditional pile types.

[0003] The main problems in the construction of rigid composite pile foundations are: the pressing of cement soil piles and concrete core piles are two completely different processes, which require multiple equipments to perform cross-operation. The construction procedures are numerous and cumbersome, resulting in a long construction period and high cost; in the process of inserting concrete core piles, soil squeezing problems are prone to occur, leading to damage to adjacent piles and adjacent buildings; it is difficult to ensure that the concrete core piles are inserted from the pile core of the cement soil piles during the construction process, resulting in the phenomenon of non-coaxiality between the concrete core piles and the cement soil piles, which greatly reduces the bearing capacity of the rigid composite piles. During construction, if the upper part is an empty pile, it is very difficult to insert the pipe piles later because the pile position of the cement soil pile after construction is difficult to find accurately. In addition, for offshore operations, since the upper part is seawater, it is difficult to find the pile position of the cement soil pile constructed in the early stage, resulting in difficulty in implanting the core piles. This has limited the use of rigid composite piles.

[0004] Therefore, how to simplify the construction process to reduce the construction period, improve the construction efficiency, and reduce the soil squeezing effect during construction are still problems that need to be solved by rigid composite piles. In addition, when the upper part is an empty pile, how to accurately position the completed cement soil pile to improve the coaxiality between the cement soil pile and the core pile is also one of the problems that need to be solved during the construction of rigid composite piles. Summary of the invention

[0005] In order to solve at least one of the above problems, the present application proposes a construction method of a rigid pipe pile using a double-wall steel pipe device to lead a hole, the double-wall steel pipe device comprising an inner steel pipe, an outer steel pipe and a prefabricated pile tip, the prefabricated pile tip being a steel structure, the prefabricated pile tip comprising an inner pipe and an outer pipe coaxially sleeved together, wherein the inner pipe is located on the inner side of the outer pipe, the inner pipe and the outer pipe are both welded to the upper side of an annular plate, and a downwardly protruding conical pile tip portion is provided on the lower side of the annular plate; a core hole in the form of a through hole is provided in the prefabricated pile tip, the core hole is coaxially provided with the inner pipe; the outer steel pipe is detachably clamped on the outer pipe, the inner steel pipe is detachably clamped on the inner pipe, and an annular cavity is formed between the inner steel pipe and the outer steel pipe; the core hole is connected to the inner cavity of the inner steel pipe through the inner pipe;

[0006] An external grouting nozzle for spraying grout to the outside of the external steel pipe is arranged at the bottom of the external steel pipe, and the external grouting pipe is fixedly connected to the external grouting nozzle;

[0007] The construction method comprises the following steps:

[0008] (1) At a set position, a pile driver is used to drive a double-walled steel pipe device to drill a pile hole. When drilling the pile hole, the pile driver is clamped on the outer steel pipe, and driven by the pile driver, the double-walled steel pipe device rotates and sinks, and cement slurry is sprayed outward through an outer grouting nozzle. The cement slurry is mixed with the underground soil to form a cement soil annular structure;

[0009] (2) When the double-wall steel pipe device sinks to the set height, the hollow prestressed pipe pile is sunk into the annular cavity;

[0010] (3) First, pull the inner steel pipe upwards so that the soil inside the inner steel pipe remains underground;

[0011] Then the outer steel pipe is rotated upward and pulled out, and cement slurry is sprayed outward through the outer grouting nozzle simultaneously to mix the cement soil annular structure to form a cement soil mixing pile.

[0012] During the specific construction process, after the inner steel pipe is pulled out, a ring-shaped channel will be left. In order to prevent the soil inside the inner steel pipe from sinking, which will cause settlement holes to form in the inner cavity at the upper end of the hollow prestressed pipe, cement slurry can also be added to the inner side of the hollow prestressed pipe pile to reduce or eliminate the formation of the above-mentioned settlement holes.

[0013] In this application, a core hole connected to the inner steel pipe is set on the prefabricated pile tip. When the double-walled steel pipe device is sunk into the ground, the underground soil can enter the inner steel pipe through the core hole to form a soil core. When the inner steel pipe is pulled out, the soil core will remain underground, reducing the backfill and transportation volume of underground soil and reducing construction costs. In addition, since no underground soil is excavated to the ground during the construction process, there is no mud pollution in the whole process, which meets environmental protection requirements.

[0014] The inner cavity of the inner steel pipe is used to accommodate part of the underground soil, reduce the soil squeezing effect, and reduce or eliminate the threat to the completed underground piles and surrounding buildings. The core hole can also reduce the end resistance of the double-walled steel pipe device when sinking, which is more conducive to the sinking of the double-walled steel pipe device, thereby forming a pile hole with a larger diameter. The outer diameter of the rigid pipe pile formed by this application can reach more than 1m.

[0015] When the double-walled steel pipe device is completely sunk, it can form an annular cavity with only an upward opening for accommodating hollow prestressed pipe piles, which solves the problem that the cement soil mixing piles that have been completed are difficult to locate when the upper part is an empty pile. At the same time, there is no problem of residual underground soil, and there is no need to clean the hole multiple times, so the hollow prestressed pipe piles can be sunk underground at one time. Since the inner and outer steel pipes are still underground when the hollow prestressed pipe piles are sunk, the wall protection function can be completed, and there will be no hole collapse or shrinkage phenomenon, which makes the application have a wide range of adaptability and can be constructed in coarse and fine sand, silt soft soil, and even cobblestone layer soil areas. The use of an annular cavity to accommodate the hollow prestressed pipe piles effectively improves the coaxiality of the cement soil mixing piles and the hollow prestressed pipe piles.

[0016] Furthermore, in order to reduce the frictional resistance between the soil core and the inner steel pipe and reduce the amount of soil carried when the inner steel pipe is pulled out, an inner grouting nozzle is provided at the bottom of the inner steel pipe, and the inner grouting pipe is fixedly connected to the inner grouting nozzle. When the double-walled steel pipe device is sunk, cement slurry is injected into the inner steel pipe through the inner grouting nozzle to form a cement slurry isolation layer on the inner wall of the inner steel pipe. The cement slurry isolation layer can effectively reduce the frictional resistance between the soil core and the inner steel pipe.

[0017] Furthermore, in order to reduce the resistance of the inner steel pipe when it is pulled out, the inner steel pipe is pulled out by rotating and lifting upwards; or the inner steel pipe is pulled out by only lifting upwards. When the inner steel pipe is pulled out by rotating and lifting upwards, not only the resistance and the pulling force when the inner steel pipe is pulled out can be reduced, but also the bonding force between the soil core and the inner steel pipe can be destroyed, so as to ensure that the soil core remains underground.

[0018] Specifically, a first clamping groove is provided on the inner pipe, and the first clamping groove is L-shaped. The first clamping groove includes a first vertical groove extending in the vertical direction and a first transverse groove connected to the bottom of the first vertical groove; in the opposite direction of the rotation direction of the double-walled steel pipe device, the first transverse groove extends from the bottom of the first vertical groove toward a direction away from the first vertical groove; a first protrusion is fixed on the outer side of the bottom of the inner steel pipe, and the first protrusion enters into the first transverse groove through the first vertical groove, so that the inner steel pipe is clamped on the inner pipe and the inner steel pipe is lined inside the inner pipe; the inner steel pipe is rotated along the rotation direction of the double-walled steel pipe device, so that the first protrusion can enter into the first vertical groove from the first transverse groove, and when the inner steel pipe is lifted upward, the inner steel pipe can be separated from the inner pipe;

[0019] A second clamping groove is provided on the external tube, and the second clamping groove is L-shaped. The second clamping groove includes a second vertical groove extending in the vertical direction and a second transverse groove connected to the bottom of the second vertical groove; along the rotation direction of the double-walled steel pipe device, the second transverse groove extends from the bottom of the second vertical groove toward a direction away from the second vertical groove; a second protrusion is fixed on the inner side of the bottom of the external steel pipe, and the second protrusion enters into the second transverse groove through the second vertical groove, so that the external steel pipe is clamped on the external tube and the external steel pipe is sleeved on the outside of the external tube; rotating the external steel pipe in the opposite direction to the rotation direction of the double-walled steel pipe device can make the second protrusion enter into the second vertical groove from the second transverse groove, and when the external steel pipe is lifted upward, the external steel pipe can be separated from the external tube.

[0020] This design enables the inner steel pipe and the outer steel pipe to be smoothly separated from the connected inner pipe and outer pipe for recovery. Since the inner steel pipe is lined inside the inner pipe and the outer steel pipe is sleeved on the outside of the outer pipe, it can effectively prevent underground soil from entering the gap between the inner steel pipe and the inner pipe, and the gap between the outer steel pipe and the outer pipe, causing blockage of the first slot or the second slot, thereby affecting the recovery of the inner steel pipe or the outer steel pipe.

[0021] Furthermore, an outer retaining ring is provided on the outer wall of the external tube. When the outer steel pipe is clamped on the external tube, the outer steel pipe is pressed against the outer retaining ring, or a gap of no more than 5 mm is provided between the outer steel pipe and the outer retaining ring. An inner retaining ring is provided on the inner wall of the core hole. When the inner steel pipe is clamped on the inner tube, the inner steel pipe is pressed against the inner retaining ring, or a gap of no more than 5 mm is provided between the inner steel pipe and the inner retaining ring. After the inner retaining ring is provided, the underground soil can at most enter the gap between the inner steel pipe and the inner retaining ring, but will not enter the gap between the inner tube and the inner steel pipe. When the outer retaining ring is provided, the underground soil can at most enter the gap between the outer steel pipe and the outer retaining ring, but will not enter the gap between the external tube and the outer steel pipe. In order to prevent underground soil from entering the gap between the inner steel pipe and the inner retaining ring, and the gap between the outer pipe and the outer steel pipe, during the specific construction process, if the outer steel pipe and the outer retaining ring are not easy to seal, a sealing ring can be placed between the outer steel pipe and the outer retaining ring to close the gap between the outer steel pipe and the outer retaining ring. And if the inner steel pipe and the inner retaining ring are not easy to seal, a sealing ring can be placed between the inner steel pipe and the inner retaining ring to close the gap between the inner steel pipe and the inner retaining ring.

[0022] Furthermore, in the radial direction, the outer circumference of the outer retaining ring does not extend outwardly beyond the outer circumference of the outer steel pipe, and in the radial direction, the inner circumference of the inner retaining ring extends inwardly beyond the inner circumference of the inner steel pipe. That is, the outer diameter of the outer retaining ring is not greater than the outer diameter of the outer steel pipe, and the inner diameter of the inner retaining ring is smaller than the inner diameter of the inner steel pipe.

[0023] When the outer circumference of the outer retaining ring does not extend outward beyond the outer circumference of the outer steel pipe, the outer diameter of the double-walled steel pipe device in the radial direction can be reduced, and the resistance of the underground soil to the sinking of the double-walled steel pipe device can be reduced. When the inner circumference of the inner retaining ring extends inward beyond the inner circumference of the inner steel pipe, the underground soil can be compressed when entering the inner steel pipe through the core hole, so that the outer diameter of the soil core formed is smaller than the inner diameter of the inner steel pipe. Although the soil core will still contact the inner wall of the inner steel pipe due to deformation after entering the inner steel pipe, the frictional resistance between the soil core and the inner steel pipe will still be reduced, so that when the inner steel pipe is pulled out, it is more conducive to keeping the soil core underground. Preferably, the inner diameter of the inner retaining ring is 5-10mm smaller than the inner diameter of the inner steel pipe.

[0024] Furthermore, in order to improve the mixing uniformity of cement slurry and underground soil, a stirring blade is provided at the bottom of the outer steel pipe, and the stirring blade is located on the outside of the outer steel pipe. Preferably, the stirring outer diameter of the stirring blade is 1.5-2.5 times the outer diameter of the hollow prestressed pipe pile. The present application has no special requirements for the structure of the stirring blade, and the stirring blade of the existing stirring pile can be applied to the present application, for example, spiral type, plate type and other stirring blades can be used.

[0025] Furthermore, in order to improve the transmission of torque between the inner steel pipe and the outer steel pipe, an inner groove is provided on the outer wall of the inner steel pipe, an outer groove is provided on the inner wall of the outer steel pipe, a synchronization plate is inserted in the annular cavity along the vertical direction, and opposite sides of the synchronization plate are respectively inserted in the inner groove and the outer groove. The synchronization plate is used as a torque transmission member between the inner steel pipe and the outer steel pipe, so that the outer steel pipe can evenly transmit the torque generated by the external force to the inner steel pipe. Preferably, the synchronization plate is only provided on the top of the inner steel pipe and the outer steel pipe, and the height of the synchronization plate is controlled between 0.3-2 meters.

[0026] Furthermore, in order to smoothly pull the inner and outer steel pipes out of the ground, both the inner and outer steel pipes need to be pulled out before the cement soil mixing piles complete initial setting. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of an embodiment of a double-wall steel pipe device.

[0028] Figure 2 This is a diagram of the state after the prefabricated pile tip is separated from the inner steel pipe and the outer steel pipe in the double-wall steel pipe device.

[0029] Figure 3 yes Figure 2 A zoomed-in view of the center AA axis.

[0030] Figure 4 yes Figure 3 Magnified view of part B.

[0031] Figure 5 It is a structural schematic diagram of the prefabricated pile tip.

[0032] Figure 6 It is a three-dimensional structural diagram of the prefabricated pile tip.

[0033] Figure 7 It is a construction flow chart of rigid pipe piles using double-walled steel pipe devices to guide holes. DETAILED DESCRIPTION

[0034] The following first describes the structure of the double-wall steel pipe device. Figure 1-Figure 6 The double-walled steel pipe device includes an inner steel pipe 12, an outer steel pipe 11 and a prefabricated pile tip 20. The prefabricated pile tip 20 is a steel structure. The prefabricated pile tip 20 includes an annular plate 23 and an inner pipe 22 and an outer pipe 21 welded on the upper side of the annular plate. The inner pipe 22 and the outer pipe 21 are coaxially sleeved together, wherein the inner pipe is located on the inner side of the outer pipe.

[0035] A conical pile tip portion protruding downward is welded to the lower side of the annular plate, and the pile tip portion includes a cylindrical core tube 25 extending in the vertical direction and a conical tube 24 welded to the outside of the core tube 25. The small end of the conical tube faces downward, and the inner cavity of the core tube is formed as a core hole 28. The core hole is a through hole, so that the core hole passes through the conical tube downward. The core hole is coaxially arranged with the inner tube and is connected to the inner cavity of the inner tube.

[0036] The outer steel pipe is detachably clamped on the outer pipe, and the inner steel pipe is detachably clamped on the inner pipe, forming an annular cavity 17 between the inner and outer steel pipes. An upwardly open annular pile tip cavity 29 is formed between the inner and outer pipes, and the annular cavity 17 is connected to the pile tip cavity 29. The core hole is connected to the inner cavity of the inner steel pipe through the inner pipe; when the double-wall steel pipe device is working, underground soil can enter the inner steel pipe through the core hole to form a soil core 33.

[0037] Specifically in this embodiment, three first slots 221 are provided on the inner tube 22, and the three first slots are evenly arranged along the circumferential direction. The first slots 221 are L-shaped, and each first slot 221 includes a first vertical slot 222 extending in the vertical direction and a first transverse slot 223 connected to the bottom of the first vertical slot; in the opposite direction of the rotation direction of the double-wall steel pipe device, the first transverse slot extends from the bottom of the first vertical slot toward a direction away from the first vertical slot. Figure 6 The direction of the arrow S in the figure indicates the rotation direction of the double-wall steel pipe device.

[0038] Three first protrusions 121 are welded on the outer side of the bottom of the inner steel pipe, and each first protrusion 121 can enter the first transverse groove through a first vertical groove of a first clamping groove, so that the inner steel pipe is clamped on the inner pipe and lined inside the inner pipe. The inner steel pipe is rotated along the rotation direction of the double-wall steel pipe device, so that the first protrusion can enter the first vertical groove from the first transverse groove, and when the inner steel pipe is lifted upward, the inner steel pipe can be separated from the inner pipe.

[0039] Three second slots 211 are provided on the external tube 21, and the three second slots are evenly arranged along the circumference. The second slots 211 are L-shaped, and each second slot 211 includes a second vertical slot 212 extending in the vertical direction and a second transverse slot 213 connected to the bottom of the second vertical slot; along the rotation direction of the double-wall steel pipe device, the second transverse slot extends from the bottom of the second vertical slot toward a direction away from the second vertical slot.

[0040] Three second protrusions 111 are welded on the inner side of the bottom of the outer steel pipe, and each second protrusion 111 can enter the second transverse groove through the second vertical groove of a second clamping groove, so that the outer steel pipe is clamped on the outer tube and the outer steel pipe is sleeved on the outer side of the outer tube. The outer steel pipe is rotated in the opposite direction of the rotation direction of the double-wall steel pipe device, so that the second protrusion can enter the second vertical groove from the second transverse groove, and when the outer steel pipe is lifted upward, the outer steel pipe can be separated from the outer tube.

[0041] In this embodiment, three first slots and three second slots are provided. In this application, there is no strict requirement on the number of the first slots and the second slots. However, in order to facilitate driving the double-wall steel pipe hole-guiding device to rotate along its central axis, at least two first slots and two second slots need to be provided. When only two first slots and two second slots are provided, the two first slots need to be arranged opposite to each other, and the two second slots also need to be arranged opposite to each other. The number of the first slots and the second slots can be controlled within 2-10.

[0042] In order to prevent the underground soil from entering the first clamping groove or the second clamping groove, thereby hindering the rotation of the inner steel pipe or the outer steel pipe, causing the inner steel pipe to be unable to detach from the inner pipe, or causing the outer steel pipe to be unable to detach from the outer pipe, in this embodiment, the outer peripheral surface of the annular plate 23 extends outward beyond the outer peripheral surface of the outer pipe, and forms an annular outer retaining ring 231. When the outer steel pipe is clamped on the outer pipe, the outer steel pipe is tightly pressed against the outer retaining ring to close the gap between the outer steel pipe and the outer pipe. Of course, in other embodiments, the outer retaining ring can also be set separately. It can be understood that in other embodiments, a gap of no more than 5 mm can be provided between the outer steel pipe and the outer retaining ring, and a sealing ring can be placed in the gap to close the gap between the outer steel pipe and the outer pipe.

[0043] In the radial direction, the outer circumference of the annular plate 23 does not extend outward beyond the outer circumference of the outer steel pipe; that is, in the radial direction, the outer circumference of the outer retaining ring does not extend outward beyond the outer circumference of the outer steel pipe to reduce resistance.

[0044] In this embodiment, in the radial direction, the inner diameter of the core tube 25 is smaller than the inner diameter of the inner tube 22, so that the core tube also serves as an inner retaining ring. When the inner steel tube is clamped on the inner tube, the inner steel tube is tightly pressed against the top end surface 251 of the core tube 25 to close the gap between the inner steel tube and the top end surface of the core tube 25. Of course, in other embodiments, the inner retaining ring can also be set separately. It is understood that in other embodiments, a gap of no more than 5 mm can be provided between the inner steel tube and the top end surface of the core tube 25, and a sealing ring is placed in the gap to close the gap between the outer steel tube and the top end surface of the core tube 25.

[0045] In this embodiment, the inner diameter of the core tube 25 is smaller than the inner diameter of the inner steel tube, so that in the radial direction, the inner circumference of the core tube 25 inwardly exceeds the inner circumference of the inner steel tube; that is, in the radial direction, the inner circumference of the inner retaining ring inwardly exceeds the inner circumference of the inner steel tube. During the construction process, underground soil will enter the inner steel tube to form a soil core 33. When the underground soil passes through the core hole, it will compress the underground soil so that the outer diameter of the formed soil core is smaller than the inner diameter of the inner steel tube. Although the soil core will still contact the inner wall of the inner steel tube due to deformation after entering the inner steel tube, it will reduce the frictional resistance between the soil core and the inner steel tube, so that when the inner steel tube is pulled out, it is more conducive to keeping the soil core underground.

[0046] The inner diameter of the core tube 25 is preferably 5-10 mm smaller than the inner diameter of the inner steel tube. Specifically in this embodiment, the inner diameter of the core tube 25 is 8 mm smaller than the inner diameter of the inner steel tube. That is, the inner diameter of the inner retaining ring is 8 mm smaller than the inner diameter of the inner steel tube.

[0047] An inner grouting pipe 272 and an outer grouting pipe 271 are arranged in the annular cavity. The inner grouting pipe and the outer grouting pipe are both connected to the grouting equipment via a rotary joint.

[0048] An inner grouting ring pipe 274 is welded at the bottom of the inner grouting pipe, and three inner grouting nozzles 262 are installed at the bottom of the inner steel pipe. The three inner grouting nozzles 262 are evenly spaced along the circumference of the inner steel pipe, and each inner grouting nozzle penetrates the pipe wall of the inner steel pipe and connects to the inner cavity of the inner steel pipe. The inner grouting ring pipe extends around the outer wall of the inner steel pipe and fits on the outer wall of the inner steel pipe. The inner grouting pipe fits on the outer wall of the inner steel pipe and extends upward from the annular cavity in the vertical direction.

[0049] An outer grouting ring pipe 273 is welded at the bottom of the outer grouting pipe, and three outer grouting nozzles 261 are installed at the bottom of the outer steel pipe. The three outer grouting nozzles 261 are evenly spaced along the circumference of the outer steel pipe, and each outer grouting nozzle penetrates the pipe wall of the outer steel pipe and connects to the outside of the outer steel pipe. The outer grouting ring pipe extends around the inner wall of the outer steel pipe and fits on the inner wall of the outer steel pipe. The outer grouting pipe fits on the inner wall of the outer steel pipe and extends upward from the annular cavity in the vertical direction.

[0050] In order to improve the uniformity of torque transmission between the outer steel pipe and the inner steel pipe, three inner clamping parts groups are welded on the outer wall of the inner steel pipe, each inner clamping part group includes five inner clamping parts 11 arranged at intervals in the vertical direction, and each inner clamping part has an inner clamping groove radially facing outward, and the inner clamping groove passes through the upper and lower end surfaces of the inner clamping part in the vertical direction.

[0051] Three external clamping member groups are welded on the inner wall of the outer steel pipe. Each external clamping member group includes five external clamping members 152 arranged at intervals in the vertical direction. Each external clamping member has an external clamping groove radially facing inward, and the external clamping groove vertically penetrates the upper and lower end surfaces of the external clamping member. Each internal clamping member group is arranged opposite to an external clamping member group in the radial direction. The internal clamping member group and the external clamping member group arranged opposite to each other together constitute a clamping member combination. Corresponding to each clamping member combination, a synchronous plate 16 is arranged. The synchronous plate 16 is inserted into the annular cavity 17 in the vertical direction, and the opposite sides of the synchronous plate are respectively inserted into the inner and outer clamping grooves of the corresponding clamping member combination. The synchronous plate is used to make the outer steel pipe evenly transfer the torque generated by the external force to the inner steel pipe.

[0052] Since the bottoms of the inner steel pipe and the outer steel pipe are both connected to the prefabricated pile tip, the inner steel pipe and the outer steel pipe can transmit torque through the prefabricated pile tip. Therefore, in another embodiment, each inner clamping member group can be provided with only one inner clamping member located at the top of the inner steel pipe, and each outer clamping member group can be provided with only one outer clamping member located at the top of the outer steel pipe, and the height of the synchronization plate can be shortened so that the synchronization plate is only provided at the top of the inner steel pipe and the outer steel pipe. When the synchronization plate is only provided at the top of the inner steel pipe and the outer steel pipe, the height of the synchronization plate can be controlled between 0.3-2 meters, specifically 0.3 meters, 0.5 meters, 1 meter, 1.5 meters or 2 meters, or other data between 0.3-2 meters.

[0053] In this embodiment, both the inner clamping member and the outer clamping member are made of channel steel, and the groove of the channel steel extends in the vertical direction, and the groove of the channel steel is used as the inner clamping groove and the outer clamping groove.

[0054] In order to strengthen the mixing of cement slurry and underground soil, a stirring blade 13 is provided at the bottom of the outer steel pipe, and the stirring blade is located outside the outer steel pipe. The stirring outer diameter of the stirring blade 13 is twice the outer diameter of the hollow prestressed pipe pile. It can be understood that in other embodiments, the stirring outer diameter of the stirring blade 13 is 1.5 times, 1.8 times, 2.2 times or 2.5 times the outer diameter of the hollow prestressed pipe pile, and of course it can also be other multiples between 1.5-2.5 times.

[0055] The following is an explanation of the construction method of the double-wall steel pipe installation and drilling method for the rigid pipe pile. Figure 7 , the construction method comprises the following steps:

[0056] (1) Please refer to Figure 7 In step (a) and step (b), at a set position, a pile driver is used to drive the double-walled steel pipe device to drill a pile hole. When drilling the pile hole, the power head of the pile driver is clamped on the outer steel pipe, and driven by the pile driver, the double-walled steel pipe device rotates and sinks. During the rotation and sinking process of the double-walled steel pipe device, underground soil enters the inner cavity of the inner steel pipe through the core hole 28 to form a soil core 33. Figure 7 In the figure, reference numeral 100 indicates the ground.

[0057] During the rotation and sinking process of the double-walled steel pipe device, cement slurry is sprayed outward through the outer grouting nozzle, and the cement slurry sprayed to the outside of the outer steel pipe is mixed with the underground soil under the stirring of the stirring blade to form a cement soil annular structure 31. At the same time, cement slurry is injected into the inner steel pipe through the inner grouting nozzle to form a cement slurry isolation layer on the inner wall of the inner steel pipe. The cement slurry isolation layer is located between the soil core and the inner steel pipe, and the friction between the soil core and the inner steel pipe is reduced by the cement slurry isolation layer.

[0058] (2) Please refer to Figure 7 In step (c), when the double-walled steel pipe device sinks to a set height, the synchronous plate is first pulled out, and then the hollow prestressed pipe pile 32 is sunk into the annular cavity.

[0059] (3) Please refer to Figure 7 In step (d) and step (e), before the cement soil mixing pile completes initial setting, the inner steel pipe and the outer steel pipe are pulled out in sequence, so that the soil core inside the inner steel pipe remains underground.

[0060] When pulling out the inner steel pipe, first rotate the inner steel pipe along the rotation direction of the double-wall steel pipe device, so that the first protrusion enters the first vertical groove from the first transverse groove, and then lift the inner steel pipe upward to separate the inner steel pipe from the inner pipe, and then completely pull the inner steel pipe out of the ground by only lifting it upward. It can be understood that in another embodiment, after the inner steel pipe is separated from the inner pipe, it can also be completely pulled out of the ground by rotating and lifting it upward.

[0061] When pulling out the outer steel pipe, first rotate the outer steel pipe in the opposite direction of the rotation direction of the double-wall steel pipe device, so that the second protrusion enters the second vertical groove from the second transverse groove, and then lift the outer steel pipe upward to separate the outer steel pipe from the external pipe; then rotate the outer steel pipe upward to pull it out, and continue to spray cement slurry through the external grouting nozzle to mix the cement soil annular structure to form a cement soil mixing pile 34. When the outer steel pipe is completely pulled out, the construction of the rigid pipe pile is completed.

Claims

1. A construction method for rigid pipe piles using double-walled steel pipes for drilling holes, characterized in that: The double-wall steel pipe device comprises an inner steel pipe, an outer steel pipe and a prefabricated pile tip, wherein the prefabricated pile tip is a steel structure, and comprises an inner pipe and an outer pipe coaxially sleeved together, wherein the inner pipe is located on the inner side of the outer pipe, and the inner pipe and the outer pipe are both welded to the upper side of an annular plate, and a downwardly protruding conical pile tip portion is provided on the lower side of the annular plate; a through-hole-shaped core hole is provided in the prefabricated pile tip, and the core hole is coaxially provided with the inner pipe; the outer steel pipe can be detachably clamped on the outer pipe, and the inner steel pipe can be detachably clamped on the inner pipe, and an annular cavity is formed between the inner steel pipe and the outer steel pipe; the core hole is connected to the inner cavity of the inner steel pipe through the inner pipe; An external grouting nozzle for spraying grout to the outside of the external steel pipe is arranged at the bottom of the external steel pipe, and the external grouting pipe is fixedly connected to the external grouting nozzle; The construction method comprises the following steps: (1) At a set position, a pile driver is used to drive a double-walled steel pipe device to drill a pile hole. When drilling the pile hole, the pile driver is clamped on the outer steel pipe, and driven by the pile driver, the double-walled steel pipe device rotates and sinks, and cement slurry is sprayed outward through an outer grouting nozzle. The cement slurry is mixed with the underground soil to form a cement soil annular structure; (2) When the double-wall steel pipe device sinks to the set height, the hollow prestressed pipe pile is sunk into the annular cavity; (3) First, pull the inner steel pipe upwards so that the soil inside the inner steel pipe remains underground; Then the outer steel pipe is rotated upward and pulled out, and cement slurry is sprayed outward through the outer grouting nozzle simultaneously to mix the cement soil annular structure to form a cement soil mixing pile.

2. The construction method according to claim 1, characterized in that: An inner grouting nozzle is provided at the bottom pipe of the inner steel pipe, and the inner grouting pipe is fixedly connected to the inner grouting nozzle. When the double-wall steel pipe device sinks, cement slurry is injected into the inner steel pipe through the inner grouting nozzle to form a cement slurry isolation layer on the inner wall of the inner steel pipe.

3. The construction method according to claim 1, characterized in that: When the inner steel pipe is pulled out, the inner steel pipe is pulled out by rotating and lifting upwards; or the inner steel pipe is pulled out by only lifting upwards.

4. The construction method according to claim 1, characterized in that: A first clamping groove is provided on the inner pipe, the first clamping groove is L-shaped, and the first clamping groove includes a first vertical groove extending in the vertical direction and a first transverse groove connected to the bottom of the first vertical groove; the first transverse groove extends from the bottom of the first vertical groove in the direction away from the first vertical groove in the opposite direction of the rotation direction of the double-wall steel pipe device; a first protrusion is fixed on the outer side of the bottom of the inner steel pipe, and the first protrusion enters into the first transverse groove through the first vertical groove, so that the inner steel pipe is clamped on the inner pipe and the inner steel pipe is lined inside the inner pipe; Rotating the inner steel pipe along the rotation direction of the double-wall steel pipe device can make the first protrusion enter the first vertical groove from the first transverse groove, and when the inner steel pipe is lifted upward, the inner steel pipe can be separated from the inner pipe; A second clamping groove is provided on the external tube, and the second clamping groove is L-shaped. The second clamping groove includes a second vertical groove extending in the vertical direction and a second transverse groove connected to the bottom of the second vertical groove; along the rotation direction of the double-walled steel pipe device, the second transverse groove extends from the bottom of the second vertical groove toward a direction away from the second vertical groove; a second protrusion is fixed on the inner side of the bottom of the external steel pipe, and the second protrusion enters into the second transverse groove through the second vertical groove, so that the external steel pipe is clamped on the external tube and the external steel pipe is sleeved on the outside of the external tube; rotating the external steel pipe in the opposite direction to the rotation direction of the double-walled steel pipe device can make the second protrusion enter into the second vertical groove from the second transverse groove, and when the external steel pipe is lifted upward, the external steel pipe can be separated from the external tube.

5. The construction method according to claim 4, characterized in that: An outer retaining ring is arranged on the outer wall of the external tube. When the outer steel tube is clamped on the external tube, the outer steel tube is pressed against the outer retaining ring, or a gap of no more than 5 mm is provided between the outer steel tube and the outer retaining ring. An inner retaining ring is arranged on the inner wall of the core hole. When the inner steel pipe is clamped on the inner pipe, the inner steel pipe is pressed against the inner retaining ring, or a gap of no more than 5 mm is provided between the inner steel pipe and the inner retaining ring.

6. The construction method according to claim 5, characterized in that: In the radial direction, the outer circumference of the outer retaining ring does not extend outward beyond the outer circumference of the outer steel pipe; and in the radial direction, the inner circumference of the inner retaining ring extends inward beyond the inner circumference of the inner steel pipe.

7. The construction method according to claim 1, characterized in that: A stirring blade is arranged at the bottom of the outer steel tube, and the stirring blade is located outside the outer steel tube.

8. The construction method according to claim 7, characterized in that: The outer diameter of the stirring blade is 1.5-2.5 times the outer diameter of the hollow prestressed pipe pile.

9. The construction method according to claim 1, characterized in that: An inner groove is arranged on the outer wall of the inner steel pipe, an outer groove is arranged on the inner wall of the outer steel pipe, a synchronous plate is inserted in the annular cavity along the vertical direction, and opposite sides of the synchronous plate are respectively inserted in the inner groove and the outer groove.

10. The construction method according to claim 1, characterized in that: Both the inner and outer steel pipes need to be pulled out before the cement-soil mixing piles complete initial setting.

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