A PHS square pile driving device

Abstract

A PHS square pile driving device belongs to the technical field of pile foundation construction equipment. The device includes a sleeve-type pile cap, a pile driver, and a buffer pad. The sleeve-type pile cap includes a side plate, a support plate, a positioning plate, and a first lifting lug. The side plate is square on all four sides. A horizontal support plate is welded to the center of the inner side of the side plate. A grout drain hole is opened at the center of the support plate. A ring-shaped positioning plate is welded below the support plate, located between the grout drain hole and the side plate. A buffer pad is placed between the positioning plate and the side plate, and the buffer pad is fixed by a circumferentially evenly arranged fastening mechanism. The first lifting lug is welded to the outer side of the side plate, close to the slot. A second lifting lug is welded to the bottom side of the pile driver. The lifting holes of the first and second lifting lugs overlap. A shackle pin is inserted into both lifting holes simultaneously to connect the pile driver to the sleeve-type pile cap. This device has the advantages of relieving stress concentration at the pile head, improving pile driving positioning accuracy, and reducing pile breakage rate.

Description

Technical Field

[0001] This utility model belongs to the technical field of pile foundation construction equipment, specifically relating to a device used in the embedded pile driving of PHS prestressed concrete square piles, which is suitable for embedded pile driving projects in clay foundations. Background Technology

[0002] In the construction of prestressed high-strength concrete square piles (PHS), especially during pile driving operations on clay foundations, the performance of the pile driving device directly affects the construction quality and efficiency. Traditional pile driving devices have significant drawbacks: First, under rigid impact, severe stress concentration occurs in the pile head area, causing not only surface damage but also internal structural cracks, seriously affecting the pile's bearing capacity. Second, due to the lack of a precise positioning mechanism, there is a mismatch between the pile driving device and the pile top interface. This mismatch leads to displacement during pile driving, affecting the pile's verticality and final elevation. The root cause of these technical defects lies in the fact that traditional pile driving devices fail to fully consider the special requirements of PHS square piles, particularly the functional needs in areas such as energy dissipation, precise positioning, and elevation control. Therefore, developing a pile driving device specifically for PHS square piles has become a pressing technical challenge for the industry. Utility Model Content

[0003] To address the aforementioned problems, this utility model proposes a PHS square pile driving device, aiming to solve the problems of stress concentration and inaccurate positioning of traditional pile drivers in PHS square pile construction.

[0004] A PHS square pile driving device is characterized by comprising a sleeve-type pile cap, a pile driver, and a buffer pad. The sleeve-type pile cap includes a side plate, a support plate, a positioning plate, and a first lifting lug. The side plate is square on all four sides. A horizontal support plate is welded to the center of the inner side of the side plate. A grout drain hole is opened at the center of the support plate. An annular positioning plate is welded below the support plate. The positioning plate surrounds the grout drain hole and is located between the outer periphery of the grout drain hole and the side plate. A neoprene rubber buffer pad is placed between the positioning plate and the side plate. The buffer pad is fixed by a circumferentially uniformly arranged fastening mechanism. The fastening mechanism includes an arc-shaped pressure plate, a tightening bolt, a disc spring washer, a positioning nut, and a locking nut. The arc-shaped pressure plate is placed between the buffer pad and the positioning plate. The tightening bolt passes through the positioning plate and the arc-shaped pressure plate. The end of the plate is fixed against the buffer pad. On the other side of the positioning plate, the positioning nut is first screwed into the tightening bolt, then a disc spring washer is placed, and then the locking nut is screwed in to fix the tightening bolt. A slot is opened on the upper part of the side plate, and the lowest point of the slot is not lower than the support plate. The first lifting lug is welded to the outer side of the side plate close to the slot. The pile driver is a square column, and its plane side length is less than the length of the side plate. The second lifting lug is welded to the bottom of the side of the pile driver. The position of the second lifting lug matches the position of the slot. After the pile driver is placed in the sleeve-type pile cap, the lifting holes of the first and second lifting lugs overlap. The shackle pin is inserted into the two lifting holes at the same time to connect the pile driver to the sleeve-type pile cap. The third lifting lug is welded to the upper side of the pile driver. A steel wire rope is threaded into the lifting hole of the third lifting lug.

[0005] Furthermore, the buffer pads are arranged symmetrically in sections with gaps, the gap width being δ=0.05h, where h is the thickness of the buffer pad. This gap width can effectively adapt to the deformation requirements generated by the rubber body fastening operation.

[0006] Furthermore, the arc-shaped pressure plates are symmetrically arranged with a gap of 5mm, which is sufficient to meet the displacement deformation compensation requirements during the rubber pad fastening process.

[0007] Furthermore, the upper corner of the buffer pad near the side plate is rounded, with an outer radius R=10mm, which ensures that the gap between the buffer pad and the pile body is ≤0.5mm, thereby effectively avoiding stress concentration.

[0008] The beneficial effects of this utility model are as follows: The sleeve-type pile cap forms a rigid frame through the enclosing side plates, and the support plate bears the main impact load and transfers part of the load to the positioning plate. During the pile driving process, the buffer pad undergoes elastic deformation under the constraint of the fastening mechanism, and the disc spring washer compensates for the fluctuation of the bolt preload. The grout discharge hole promptly discharges the mud at the pile-soil interface, preventing pressure accumulation that could cause the pile to float. The pile driver achieves a rigid connection with the pile cap through the lifting lug and shackle, and the steel wire rope passing through the third lifting lug provides a stable lifting support point. After the impact energy is absorbed by the deformation of the buffer pad and dissipated elastically by the fastening mechanism, the remaining energy is evenly transferred to the pile body through the sleeve structure. Through the precise positioning connection structure between the sleeve-type pile cap and the pile driver, the elastic buffer design of the neoprene rubber buffer pad, and the multiple coordinations of the arc-shaped pressure plate fastening mechanism, the impact stress is effectively dispersed and the verticality of the pile body is maintained. This has the advantages of alleviating stress concentration at the pile head, improving pile driving positioning accuracy, and reducing the pile damage rate. Attached Figure Description

[0009] Figure 1 This is a side sectional view of a PHS square pile driving device.

[0010] Figure 2 This is a side cross-sectional view of a sleeve-type pile cap.

[0011] Figure 3 A top view of the assembly of the sleeve-type pile cap and the pile driver.

[0012] Figure 4 This is a bottom view of the sleeve-type pile cap.

[0013] Figure 5 This is a magnified view of the details at point A.

[0014] Among them: 1-side plate, 2-buffer pad, 3-first lifting lug, 4-second lifting lug, 5-third lifting lug, 6-pile body, 7-arc pressure plate, 8-positioning plate, 9-tightening bolt, 10-positioning nut, 11-locking nut, 12-support plate, 13-pile driver, 14-wire rope, 15-shackle pin, 16-slot, 17-grout drain hole, 18-disc spring washer. Detailed Implementation

[0015] Example 1: In existing technology, rigid pile drivers are commonly used for driving prestressed concrete square piles in clay foundations. Traditional devices rely on metal components to directly transmit impact loads, leading to stress concentration in the pile head area. Under complex geological conditions, the interface between the pile driver and the pile top is prone to lateral displacement, causing pile axis misalignment. Due to the lack of an energy dissipation mechanism, repeated impacts during pile driving can easily cause concrete spalling at the pile head, affecting construction quality. Therefore, this application proposes a PHS square pile driving device, which includes a sleeve-type pile cap, a pile driver 13, and a buffer pad 2. The sleeve-type pile cap is formed by four side plates 1 enclosing a square structure. A horizontal support plate 12 is welded to the inner side of the side plates 1. A grout drain hole 17 is opened in the center of the support plate 12, and an annular positioning plate 8 is welded below it. A neoprene rubber buffer pad 2 is placed between the positioning plate 8 and the side plates 1. The buffer pad 2 is fixed by a circumferentially distributed fastening mechanism. The fastening mechanism includes an arc-shaped pressure plate 7, a top-tightening bolt 9, a disc spring washer 18, a positioning nut 10, and a locking nut 11. The arc-shaped pressure plate 7 is placed between the buffer pad 2 and the positioning plate 8. The top-tightening bolt 9 passes through the positioning plate 8 and the arc-shaped pressure plate 7, and its end presses against the buffer pad 2 to fix it. The positioning nut 10 is first screwed into the bolt of the top-tightening bolt 9 located on the other side of the positioning plate 8, then the disc spring washer 18 is placed, and finally the locking nut 11 is screwed in to fix the top-tightening bolt 9. A slot 16 is made above the side plate 1, and the lowest point of the slot 16 is not lower than the support plate 12. The first lifting lug 3 is welded to the outside of the side plate 1, close to the slot 16. The pile driver 13 is a square column, and its side length is less than the length of the side plate 1. The second lifting lug 4 is welded to the bottom of the side of the pile driver 13. The position of the second lifting lug 4 matches the position of the slot 16. After the pile driver 13 is placed in the sleeve-type pile cap, the lifting holes of the first lifting lug 3 and the second lifting lug 4 overlap. The shackle pin 15 is inserted into the two lifting holes at the same time to connect the pile driver 13 to the sleeve-type pile cap. The third lifting lug 5 is welded to the upper side of the pile driver 13. The steel wire rope 14 is threaded into the lifting hole of the third lifting lug 5.

[0016] The sleeve-type pile cap side plate 1 is made of steel plate, and its internal support plate 12 and positioning plate 8 form a layered bearing system to disperse impact loads. The buffer pad 2 is an elastic medium placed between rigid components, made of neoprene rubber, which absorbs impact kinetic energy and reduces stress peaks. The buffer pad 2 is 60mm (±2mm) thick and adopts a split symmetrical arrangement, specifically, the entire buffer pad 2 is cut into two symmetrical parts along the centerline. This arrangement allows each unit to deform independently under load, avoiding mutual compression between adjacent areas. A gap of 3mm is left between the two separated buffer pads 2. This width provides space for the compression deformation of the buffer pad 2 and prevents positioning inaccuracies due to excessive gap. The upper corner of the buffer pad 2 near the side plate 1 is rounded, with an outer radius R=10mm, ensuring that the gap between the buffer pad 2 and the top of the pile 6 is ≤0.5mm. When the buffer pad 2 contacts the pile 6, the rounded corner structure transforms the original right-angle contact area into a smooth transition curved surface contact, causing the contact stress to change from a linear distribution to a planar distribution. By limiting the outer radius, a gradient deformation zone is formed at the edge of the contact surface while ensuring the structural integrity of the buffer pad. This deformation zone generates elastic deformation during compression, gradually absorbing impact energy and preventing local stress from exceeding the material's yield strength. Simultaneously, gap control, through matching the rounded corner curvature with the assembly dimensions, ensures uniform contact between the buffer pad 2 and the pile 6, eliminating unilateral compression caused by assembly errors.

[0017] In addition, the arc-shaped pressure plates 7 are also symmetrically arranged, that is, the two arc-shaped pressure plates 7 are distributed in a mirror symmetrical manner along the central axis of the annular positioning plate, and a 5mm gap is left between the two arc-shaped pressure plates 7. This arrangement can make the clamping force evenly transmitted to the surface of the buffer pad 2. The gap width provides a deformation compensation channel for the lateral expansion of the buffer pad after being compressed.

[0018] The preload of the top bolt 9 is ≥150kN, and a disc spring washer 18 with a preload of 1.5mm is provided between the locking nut 11 and the positioning nut 10 to provide a continuous locking force ≥8kN.

[0019] During construction, the sleeve-type pile cap is first placed on top of the pile body 6. The pile driver 13 is then hoisted into the sleeve-type pile cap using the wire rope 14. The second lifting lug 4 of the pile driver 13 is initially aligned with the first lifting lug 3 using the slot 16. Subsequently, the pile driver 13 and the sleeve-type pile cap are fixedly connected using the shackle pin 15, and the pile driver 13 is then subjected to hammering and pressure application. After the pile is driven, the shackle pin 15 is released, and the pile driver 13 is removed from the sleeve-type pile cap again using the wire rope 14 for reuse.

Claims

1. A PHS square pile driving device, characterized in that: The system includes a sleeve-type pile cap, a pile driver, and a buffer pad. The sleeve-type pile cap comprises a side plate, a support plate, a positioning plate, and a first lifting lug. The side plate is square on all four sides, with a horizontal support plate welded to the center of the inner side of the side plate. A grout drain hole is located at the center of the support plate. A ring-shaped positioning plate is welded below the support plate, surrounding the grout drain hole and positioned between the grout drain hole and the side plate. A neoprene rubber buffer pad is placed between the positioning plate and the side plate. The buffer pad is fixed by a circumferentially evenly arranged fastening mechanism, which includes an arc-shaped pressure plate, a tightening bolt, a disc spring washer, a positioning nut, and a locking nut. The arc-shaped pressure plate is placed between the buffer pad and the positioning plate. The tightening bolt passes through the positioning plate and the arc-shaped pressure plate, and its end presses against the buffer pad. To secure it, first screw a positioning nut into the top bolt screw located on the other side of the positioning plate, then place a disc spring washer, and finally screw in a locking nut to secure the top bolt. A slot is made above the side plate, with the lowest point of the slot not lower than the support plate. The first lifting lug is welded to the outer side of the side plate, close to the slot. The pile driver is a square column with a side length smaller than the side plate length. A second lifting lug is welded to the bottom side of the pile driver, matching the position of the slot. After placing the pile driver inside the sleeve-type pile cap, the lifting holes of the first and second lifting lugs overlap. Use a shackle pin to simultaneously insert into both lifting holes to connect the pile driver to the sleeve-type pile cap. A third lifting lug is welded to the upper side of the pile driver, and a steel wire rope is threaded through the lifting hole of the third lifting lug.

2. The PHS square pile driving device as described in claim 1, characterized in that... The buffer pads are arranged symmetrically in two sections with gaps between them.

3. The PHS square pile driving device as described in claim 1, characterized in that... The arc-shaped pressure plates are symmetrically arranged with gaps between them.

4. The PHS square pile driving device as described in claim 1, characterized in that... The upper corner of the buffer pad near the side plate is rounded.

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