Prefabricated pipe pile air pressure auxiliary precession pile pressing method used for soft and hard interaction layer working condition

Abstract

The invention discloses an air-pressure-assisted precession pile pressing method for a prefabricated pipe pile used for a soft and hard interaction layer working condition. The prefabricated pipe pile comprises a pile body, a pile head, a rotary supporting piece and a jet swirling rod. The jet swirling rod is fixedly connected with the pile head through a fixer carried by the pile head, and a jet pipe in the jet swirling rod is connected with a gas guide groove in the pile head; air nozzles and drilling threads are distributed on the surface of the pile head. According to the pile sinking method for the prefabricated pipe pile, the air pressure is used for assisting the screw-in pile pressing system, air curtain resistance reduction and pile head screw-in are combined, the integrated operation of penetration and pile forming is achieved, hole guiding is not needed, and the conventional procedures of secondary drilling pretreatment, backfilling, re-pressing and the like are avoided. The equipment can work continuously, multiple sets of machines and tools do not need to go in and out of the site repeatedly, mechanical and labor cost is saved, and the equipment is suitable for soft-hard interaction strata and high in construction efficiency.

Description

Technical Field

[0001] This application relates to the field of static pressure precast pipe pile technology on soft soil foundation, and in particular to a pneumatic-assisted rotary pile driving method for precast pipe piles in soft-hard interlayer conditions. Background Technology

[0002] Precast pipe piles have advantages such as high bearing capacity, good bending performance, and low engineering cost. They can effectively reduce roadbed settlement and are widely used in high embankment sections at highway bridgeheads, widening sections, and general sections with large soft soil depths on soft soil foundations, with good treatment effects.

[0003] Precast pipe piles are often driven using the static pressure method, which involves driving the precast pile into the soil using the self-weight of the pile driver and the reaction force of the counterweight on the frame. This method is relatively low-cost and has minimal impact on the surrounding environment. Static pressure pipe piles mainly consist of a pile body and a pile tip. During construction, the pile tip "pierces" into the soil under static pressure, causing minimal soil disturbance and facilitating the utilization of end resistance, thereby improving the pile tip bearing capacity. However, in areas with extremely deep soft soil foundations, the penetration resistance at the pile tip increases significantly with depth, and the soil compression effect intensifies, making it difficult for the precast pipe pile to penetrate to the design bearing layer, thus affecting the load transfer to deeper layers. When the strata at the pile driving location are a soft-hard interlayer composed of soft soil and dense sand, it is difficult for the pile body to penetrate or pass through the hard soil interlayer.

[0004] To address these issues, traditional construction methods often involve drilling or water jetting at the pile driving location to ensure that the precast pipe piles reach the predetermined bearing stratum. However, this method reduces the soil squeezing effect at the drilling site, weakening the pile's side friction and leading to uncontrollable pile bearing capacity. Furthermore, secondary drilling significantly reduces construction efficiency and economic benefits. Summary of the Invention

[0005] In view of the above-mentioned technical problems, the present invention aims to propose a pneumatic-assisted rotary pile driving method for precast pipe piles in soft-hard interlayer conditions. This method can not only solve the construction adaptability problem of pipe piles being difficult to penetrate hard soil interlayers or sand layers, but also has less impact on the pile body, higher pile driving quality, and higher construction efficiency and economic benefits.

[0006] To achieve the above-mentioned technical objectives, the present invention provides the following technical solution: A pneumatic-assisted rotary pile driving method for precast pipe piles in soft-hard interaction layer conditions, wherein the precast pipe pile includes a pile body, a pile head, a rotary support, and a jet-driven rotary rod; the bottom of the pile body and the pile head are connected by the rotary support. The upper part of the pile head is provided with a fixing device, and the fixing device is provided with a cavity for the jet rotary rod to be inserted. The cavity wall is provided with an elastic locking device that can extend and retract radially along the cavity. The side wall of the jet rotary rod is provided with a limiting groove that cooperates with the elastic locking device to limit the axial displacement of the jet rotary rod relative to the pile head. The cavity is provided with a circumferential displacement limiting structure to limit the circumferential rotation of the jet rotary rod. The pile head includes a conical tip, the front surface of which is provided with drilling threads, the rear surface of which is provided with multiple air jet holes evenly distributed in a ring, and the inside of which is provided with an air guide groove communicating with the air jet holes; The jet rotating rod is equipped with a jet channel inside, which is connected to the air guide groove of the pile head. In soft soil, static pressure is applied to the pile body. Under the action of pressure, the pile head penetrates the soil and the pile body moves into the soil. At the same time, jets are sprayed into the jet rotating rod. The gas passes through the jet channel and air guide groove in sequence and is discharged from the jet hole, forming an air curtain around the pile, thereby reducing the frictional resistance around the pile. When the pile encounters a hard interlayer during the pile driving process, the external rotating drive device rotates the jet swivel rod, which drives the pile head to rotate and break through the hard interlayer, thereby accelerating the pile driving rate. When the pile body is pressed down and leaves the hard interlayer and re-enters the soft soil layer, the external rotation drive device drives the jet swivel rod to stop rotating and continue to apply static pressure downwards; After the pile driving is completed, the jet-driven rotating rod is pulled out of the fixture and moved to the next position to repeat the construction.

[0007] Beneficial effects:

[0008] First, the rotary pile driving technology provided by this invention combines the technological advantages of static pile driving and drilling operations. By setting a spiral drill bit at the pile tip to weaken the resistance of hard interlayers, continuous penetration is achieved, which effectively reduces the difficulty of pile driving when passing through hard soil interlayers, gravel layers, or dense sand layers, and significantly improves construction efficiency.

[0009] Secondly, the pneumatic-assisted rotary pile driving system enables integrated penetration and pile formation, avoiding conventional secondary drilling pretreatment, backfilling, and re-pressurization processes. The equipment can operate continuously, eliminating the need for multiple sets of equipment to repeatedly enter and exit the site, saving on machinery and labor costs, and facilitating standardization and mass production.

[0010] Third, the pneumatic-assisted rotary pile driving method for precast pipe piles used in soft-hard interlayer conditions allows for the simultaneous injection of high-pressure air around the pile via the drill bit during the pile driving process. This creates an air curtain at the pile-soil interface, effectively reducing the dynamic friction coefficient between the pile and the soil. The air curtain's resistance reduction is also timely and reversible; once pile driving is completed and air injection stops, the air curtain disappears, and the frictional resistance at the pile-soil interface recovers, minimizing the impact on the long-term bearing capacity of the pile.

[0011] In one alternative embodiment, before construction, the soil is detected by a detection device to determine the distribution of soft soil layers and hard interlayers, and then the static pressure equipment and external rotation drive device are controlled by a controller to achieve automated construction.

[0012] In one optional embodiment, the pile head further includes an air guide adapter plate; the lower side of the air guide adapter plate is fixed to a conical tip, and the upper side is fixed to a fixture, and the air guide adapter plate is provided with an air guide channel communicating with the air guide groove.

[0013] Beneficial effects: The pile head is divided into three components: a fixing device, an air guide disc, and a conical tip. The fixing device and the conical tip are connected by the air guide disc, which can ensure the airtightness of the air guide passage of the device, reduce the manufacturing process difficulty when carving the air guide groove in the pile head, and reduce manufacturing costs.

[0014] In one alternative embodiment, the resilient locking device includes a spring and a ball bearing.

[0015] Beneficial effects: The use of springs and ball bearings as elastic locking devices not only limits the axial displacement of the jet-driven rotating rod relative to the pile head, but also facilitates the removal of the jet-driven rotating rod from the fixing cavity after construction.

[0016] In one optional embodiment, the circumferential displacement limiting structure includes: A recessed and convex groove is provided at the bottom of the cavity; The lower end of the jet rotary rod is provided with a shape that fits into the groove at the bottom of the cavity.

[0017] Beneficial effects: This design limits the circumferential displacement of the jet-driven rotating rod relative to the pile head, ensuring that slippage does not occur when the jet-driven rotating rod drives the conical tip to rotate.

[0018] In one alternative embodiment, a rubber pad is adhered to the surface of the groove for airtight cushioning.

[0019] Beneficial effects: Placing a rubber pad with a certain degree of elasticity between the jet rotating rod and the contact surface of the groove can not only ensure that the high-pressure gas does not leak from the gap between the two contact surfaces, but also serve as a buffer device to protect the jet rotating rod and the groove, so that they do not collide when the jet rotating rod starts to rotate, thus ensuring the integrity of their structures.

[0020] In one alternative embodiment, the jet-driven rotating rod includes a fixed rod and at least one connecting rod section; The fixed rod and the connecting rod, as well as the two connecting rods, are connected by threaded screws.

[0021] In one optional embodiment, the outer diameter of the jet rotary rod is 40mm~50mm, and the diameter of the jet channel is 15mm~20mm; The diameter of the jet hole is 2mm to 5mm, and the air guide groove is a tubular structure with the same diameter as the jet hole.

[0022] Beneficial effects: This aperture design ensures that the airflow velocity during jetting is neither too high nor too low, guaranteeing that the airflow forms a stable air curtain around the pile. It has a certain loosening effect on the soil around the pile without damaging the structure of the soil around the pile, ensuring that the frictional resistance around the pile will not be significantly reduced due to the damage to the structure of the soil around the pile after construction.

[0023] In one alternative embodiment, the pile body is composed of multiple precast concrete pipe piles connected by a welding fixing device, and a rotating support is fixed at the bottom of the lowest pile body.

[0024] In summary, the pneumatic-assisted rotary pile driving method of the present invention overcomes the problem of penetrating hard soil interlayers through the coordinated operation of rotary driving, static pressure and air curtain, resulting in efficient pile construction, controllable quality, cost savings and reliable bearing capacity, providing an efficient solution for the construction of precast pipe piles in complex strata. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the complete structure of the precast pipe pile of the present invention; Figure 2 This is a side cross-sectional view of the precast pipe pile of the present invention; Figure 3 This is an enlarged structural diagram of the precast pipe pile head of the present invention; Figure 4 This is an enlarged view of the jet-driven rotating rod fixing device of the present invention; Figure 5 This is an enlarged schematic diagram of the connection between the jet rotary rod fixing rod and the connecting rod of the present invention; Figure 6 This is a schematic diagram showing the connection between the jet-driven rotating rod fixing rod and the pile head fixing device of the present invention; Wherein: 1 is the pile head, 2 is the pile body, 3 is the air jet rotating rod, 4 is the rotating support; 11 is the air jet hole, 12 is the air guide groove, 13 is the fixer, 14 is the air guide adapter plate, 15 is the drilling thread, 16 is the conical tip; 17 is the annular protrusion, 21 is the pile body connector, 22 is the bottom pile body, 23 is the welding fixing device; 31 is the outer wall of the air jet rotating rod, 32 is the air jet channel; 131 is the spring, 132 is the spherical ball, 133 is the concave-convex groove, 134 is the rubber gasket; 311 is the fixing rod, 312 is the connecting rod, 313 is the external thread pipe joint, 314 is the internal thread pipe joint. Detailed Implementation

[0026] To make the technical means, creative features, achieved objectives, and effects of this invention easier to understand, the invention is further described below with reference to specific embodiments. However, the following embodiments are merely preferred embodiments of this invention and not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments described herein without creative effort are all within the protection scope of this invention.

[0027] A pneumatic-assisted rotary pile driving method for precast pipe piles in soft-hard interlayer conditions, referring to Figure 1 The precast pipe pile includes a pile body 2, a pile head 1, a rotating support 4, and a jet-driven rotating rod 3; The bottom of the pile body 2 is connected to the pile head 1 by a rotating support 4; the rotating support 4 serves as a load transfer medium, transferring the static pressure on the pile body 2 to the pile head 1 while allowing the pile head 1 and the pile body 2 to rotate relative to each other.

[0028] The upper part of the pile head 1 is provided with a fixing device 13, and the fixing device 13 is provided with a cavity for the jet rotary rod 3 to be inserted. The cavity wall is provided with an elastic locking device that can extend and retract radially along the cavity. The side wall of the jet rotary rod 3 is provided with a limiting groove that cooperates with the elastic locking device to limit the axial displacement of the jet rotary rod 3 relative to the pile head 1. The cavity is provided with a circumferential displacement limiting structure to limit the circumferential rotation of the jet rotary rod 3. The jet rotary rod 3 is used to spray air to the pile head and provide knob force.

[0029] The pile head 1 includes a conical tip 16, the front surface of the conical tip 16 is provided with a drilling thread 15, the rear surface of the conical tip 16 is provided with a plurality of air jet holes 11 evenly distributed in an annular shape, and the inside of the conical tip 16 is provided with an air guide groove 12 communicating with the air jet holes 11. The jet rotating rod 3 is provided with a jet channel 32 inside, which is connected to the air guide groove 12 of the pile head 1. In the soft soil layer, static pressure is applied to the pile body. Under the action of pressure, the pile head penetrates into the soil and the pile body moves into the soil. At the same time, jets are sprayed into the jet rotating rod. The gas passes through the jet channel and the air guide groove in sequence and is discharged from the jet hole, forming an air curtain around the pile, thereby reducing the frictional resistance around the pile. When the pile encounters a hard interlayer during the pile driving process, the external rotating drive device rotates the jet swivel rod, which drives the pile head to rotate and break through the hard interlayer, thereby accelerating the pile driving rate. When the pile body is pressed down and leaves the hard interlayer and re-enters the soft soil layer, the external rotation drive device drives the jet swivel rod to stop rotating and continue to apply static pressure downwards; After the pile driving is completed, the jet-driven rotating rod is pulled out of the fixture and moved to the next position to repeat the construction.

[0030] Specifically, refer to Figure 1In this embodiment, the pile body 2 includes a pile body connector 21, a bottom pile body 22, and a welding fixing device 23; the pile body connector 21 and the bottom pile body 22 are fixed by the welding fixing device 23.

[0031] Reference Figure 2 In this embodiment, the jet-driven rotating rod 3 includes an outer wall 31 and a jet-driven channel 32, which communicates with the air guide groove 12 in the air guide adapter plate 14. Dividing the pile head into three components—a fixing device, an air guide rotating plate, and a conical tip—and connecting the fixing device and the conical tip via the air guide rotating plate ensures the airtightness of the device's air guide passage, reduces the manufacturing difficulty of carving the air guide groove on the pile head, and lowers manufacturing costs.

[0032] Reference Figure 4 In this embodiment, the fixture 13 includes a spring 131, a spherical ball bearing 132, a groove 133, and a rubber pad 134. The lower side wall of the fixing rod 311 has a groove. When the fixing rod 311 is pressed into the fixture 13, the spherical ball bearing 132 is embedded in the groove on the side wall of the fixing rod 311, thereby limiting the up-and-down movement of the fixing rod 311. The selection of a spring and a spherical ball bearing as an elastic locking device not only limits the axial displacement of the air jet rotating rod relative to the pile head, but also facilitates the removal of the air jet rotating rod from the fixture cavity after construction.

[0033] Reference Figure 6 The groove 133 is used to limit the horizontal movement of the jet rotating rod 3. The lower end of the fixing rod 311 has an irregular shape and can be fitted into the groove 133 below the fixing device 13. Through this design, the circumferential displacement of the jet rotating rod relative to the pile head is limited, ensuring that the jet rotating rod will not slip when it drives the conical tip to rotate.

[0034] Furthermore, the rubber gasket 134 is adhered to the surface of the groove 133 for buffering and sealing.

[0035] Reference Figure 5 In this embodiment, the jet-driven rotating rod 3 is divided into a fixed rod 311 and a connecting rod 312; the upper end of the fixed rod 311 is a threaded pipe connector 313; the lower end of the connecting rod 312 is a threaded pipe connector 314, and the upper end is a threaded pipe connector 313; when connecting the rods, the threaded pipe connector 313 at the upper end of the fixed rod 311 and the threaded pipe connector 314 at the lower end of the connecting rod 312 are screwed together to fix them.

[0036] Furthermore, the jet rotary rod 3 is made of high-strength and corrosion-resistant 420 stainless steel, with an outer diameter of 40mm~50mm and a jet channel 32 diameter of 15mm~20mm; the jet hole 11 has a diameter of 2mm~5mm; the air guide groove 12 is tubular with a diameter of 2mm~5mm; and the rubber gasket 134 is made of butyl rubber with excellent airtightness.

[0037] The pile body is composed of multiple precast concrete pipe piles connected by a welding fixing device. The rotating support is a bearing. The outer ring of the bearing is fixed to the bottom of the bottom pile body, and the inner ring of the bearing is fixedly connected to the annular protrusion 17 on the pile head.

[0038] In this invention, unless otherwise explicitly specified and limited, "upper" and "lower" refer to differences in horizontal height.

[0039] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A pneumatic-assisted rotary pile driving method for precast pipe piles in soft-hard interlayer conditions, wherein the precast pipe pile comprises: The pile body, pile head, rotating support, and jet-driven rotating rod; The bottom of the pile body and the pile head are connected by a rotating support; The upper part of the pile head is provided with a fixing device, and the fixing device is provided with a cavity for the jet rotary rod to be inserted. The cavity wall is provided with an elastic locking device that can extend and retract radially along the cavity. The side wall of the jet rotary rod is provided with a limiting groove that cooperates with the elastic locking device to limit the axial displacement of the jet rotary rod relative to the pile head. The cavity is provided with a circumferential displacement limiting structure to limit the circumferential rotation of the jet rotary rod. The pile head includes a conical tip, the front surface of which is provided with drilling threads, the rear surface of which is provided with multiple air jet holes evenly distributed in a ring, and the inside of which is provided with an air guide groove communicating with the air jet holes; The jet-driven rotating rod has an internal jet channel that communicates with the air guide groove of the pile head. Its characteristic is that... In soft soil layers, static pressure is applied to the pile body. Under the action of pressure, the pile head penetrates into the soil and the pile body moves into the soil. At the same time, air is sprayed into the air jet rotating rod. The gas passes through the air jet channel and air guide groove in sequence and is discharged from the air jet hole, forming an air curtain around the pile, thereby reducing the frictional resistance around the pile. When the pile encounters a hard interlayer during the pile driving process, the external rotating drive device rotates the jet swivel rod, which drives the pile head to rotate and break through the hard interlayer, thereby accelerating the pile driving rate. When the pile body is pressed down and leaves the hard interlayer and re-enters the soft soil layer, the external rotation drive device drives the jet swivel rod to stop rotating and continue to apply static pressure downwards; After the pile driving is completed, the jet-driven rotating rod is pulled out of the fixture and moved to the next position to repeat the construction.

2. The method for pneumatic-assisted rotary pile driving of precast pipe piles for soft-hard interlayer conditions according to claim 1, characterized in that, Before construction, the soil is detected by a detection device to determine the distribution of soft soil layers and hard interlayers. Then, the static pressure equipment and external rotation drive device are controlled by a controller to achieve automated construction.

3. The pneumatic-assisted rotary pile driving method for precast pipe piles in soft-hard interlayer conditions according to claim 1, characterized in that, The pile head also includes an air guide adapter plate; the lower side of the air guide adapter plate is fixed to a conical tip, and the upper side is fixed to a fixing device. The air guide adapter plate is provided with an air guide channel that communicates with the air guide groove.

4. The pneumatic-assisted rotary pile driving method for precast pipe piles in soft-hard interlayer conditions according to claim 3, characterized in that, The elastic locking device includes a spring and a ball bearing.

5. The pneumatic-assisted rotary pile driving method for precast pipe piles in soft-hard interlayer conditions according to claim 4, characterized in that, The circumferential displacement limiting structure includes: A recessed and convex groove is provided at the bottom of the cavity; The lower end of the jet rotary rod is provided with a shape that fits into the groove at the bottom of the cavity.

6. The pneumatic-assisted rotary pile driving method for precast pipe piles in soft-hard interlayer conditions according to claim 5, characterized in that, The surface of the groove is covered with a rubber pad for airtight cushioning.

7. The pneumatic-assisted rotary pile driving method for precast pipe piles in soft-hard interlayer conditions according to claim 1, characterized in that, The jet-driven rotating rod includes a fixed rod and at least one connecting rod section; The fixed rod and the connecting rod, as well as the two connecting rods, are connected by threaded screws.

8. The pneumatic-assisted rotary pile driving method for precast pipe piles in soft-hard interlayer conditions according to claim 1, characterized in that, The outer diameter of the jet rotary rod is 40mm~50mm, and the diameter of the jet channel is 15mm~20mm; The diameter of the jet hole is 2mm to 5mm, and the air guide groove is a tubular structure with the same diameter as the jet hole.

9. The pneumatic-assisted rotary pile driving method for precast pipe piles in soft-hard interlayer conditions according to claim 1, characterized in that, The pile body is composed of multiple precast concrete pipe piles connected by a welding fixing device. The rotating support is a bearing, with the outer ring of the bearing fixed to the bottom of the pile body and the inner ring of the bearing fixedly connected to the annular protrusion on the pile head.

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