An in-situ loaded tension pile and its construction method

Abstract

This application relates to an in-situ loaded tension pile and a construction method for the tension pile. The in-situ loaded tension pile includes a precast tension pile with a connector embedded inside, parallel to the pile body. The connector extends beyond the top of the precast tension pile, and an extension rod is detachably connected to the connector. The construction method for the in-situ loaded tension pile includes the following steps: S1, driving the precast tension pile into the ground and connecting the extension rod; S2, continuing to drive the pile to the desired elevation; S3, after the precast tension pile reaches the desired elevation, pulling out the driving rod and filling the pile hole with loose sand; S4, setting up a static load testing device for the pile tension at the pile hole and connecting the extension rod to the testing device, then conducting an in-situ loading test on the precast tension pile; S5, after the test, dismantling the static load testing device for the pile tension and removing the extension rod; S6, backfilling the pile hole. This application has the advantages of improving testing accuracy, reducing construction costs, and accelerating construction progress.

Description

Technical Field

[0001] This application relates to the field of pile foundation testing, and in particular to an in-situ loaded tension pile and a construction method for the tension pile. Background Technology

[0002] Uplift piles refer to piles driven into underground structures of building projects when the soil level is lower than the surrounding water level, in order to counteract the buoyancy force exerted on the structure by water in the soil. They are widely used in anti-buoyancy of large basements, anti-uplift of tall buildings (structures), anti-uplift of offshore dock platforms, anchor pile foundations of suspension bridges and cable-stayed bridges, pile foundations of large dock floor slabs, and anchor pile foundations in static load test piles, etc.

[0003] After the tension piles are driven into the ground, it is necessary to measure the load and deformation of a single pile under vertical load to determine whether the vertical tension bearing capacity of the single pile meets the design requirements. When performing load testing on tension piles in existing basements, the entire tension pile to be tested is located underground. Generally, a splice is made at the top of the pile to be tested, so that the spliced ​​pile extends out of the ground, thus facilitating in-situ load testing of the tension pile on the ground.

[0004] The pile bearing capacity obtained through the above testing methods needs to be adjusted to remove the excess friction from the upper splice. However, the actual excess friction from the splice cannot be obtained through testing and can only be estimated theoretically, leading to inaccurate pile bearing capacity data from conventional in-situ loading tests. In addition, the upper splice portion of the tension pile needs to be removed later, which not only wastes materials and labor but also affects the construction progress. Summary of the Invention

[0005] In order to obtain accurate data on pile foundation bearing capacity, reduce construction costs, and accelerate construction progress, this application provides an in-situ loaded tension pile and a construction method for the tension pile.

[0006] Firstly, for convenience, the in-situ loading anti-uplift pile provided in this application adopts the following technical solution:

[0007] An in-situ loaded tension pile includes a precast tension pile, wherein a connector parallel to the pile body is pre-embedded inside the precast tension pile, the connector extends out of the pile top of the precast tension pile, and an extension rod is detachably connected to the connector. After the precast tension pile is driven into the ground, the end of the extension rod is higher than the ground surface.

[0008] By adopting the above technical solution, precast tension piles with connectors are driven into the ground during construction. When the top of the precast tension pile is close to the ground, the extension rod is connected to the connector. Then, the precast tension pile is driven to the specified elevation, and the pile hole is filled with loose sand. Then, a static load test device for pile tension is set up at the pile hole, and the extension rod is connected to the static load test device for pile tension to conduct the test. After the test is completed, the extension rod is removed, and the pile hole is backfilled to complete the construction.

[0009] Since precast tension piles do not require splicing at the top for testing, there is no additional friction from splicing at the top of the precast tension pile. Furthermore, the friction between the extension rod and the sand is extremely small and negligible, allowing for accurate pile foundation bearing capacity data to be obtained. Eliminating the need to remove the spliced ​​portion of the precast tension pile reduces construction costs and accelerates the construction process.

[0010] Optionally, the connector is a screw, and the end of the extension rod is hollow and threadedly connected to the screw.

[0011] By adopting the above technical solution, using a screw as a connector and threadedly connecting the extension rod and the screw, firstly, the threads on the screw surface increase the connection stability between the screw and the precast tension pile, making it less likely for the screw to detach from the precast tension pile, thus meeting the strength requirements of the test. Secondly, the threaded connection is simple, convenient, and secure. The screw and extension rod are connected through the interlocking of their threads, which can withstand large tensile and shear forces and are not prone to loosening. Therefore, the connection between the screw and the extension rod is reliable during the test.

[0012] Optionally, a steel cage is pre-embedded inside the precast anti-tension pile. Two limiting bars are arranged parallel to each other on the steel cage. The limiting bars are arranged perpendicular to the screw rod. The screw rod is located between the two limiting bars. A limiting arc groove is opened on the screw rod, and the limiting bars are partially embedded in the limiting arc groove.

[0013] By adopting the above technical solution, the screw is clamped by two limiting ribs and partially embedded in the limiting arc groove, so that the limiting ribs play an axial limiting role on the screw, making the connection between the screw and the precast pull-out pile more reliable.

[0014] Optionally, the connector is located at the center of the top of the precast tension pile.

[0015] By adopting the above technical solution, the connector is placed at the center of the top of the precast tension pile, so that the precast tension pile bears a vertically upward force during the test, making the force on the precast tension pile more uniform and improving the accuracy of the test data.

[0016] Optionally, a limiting plate is provided at the top of the precast tension pile, and a limiting ring groove is formed on the limiting plate. The center of the limiting ring groove coincides with the axis of the extension rod. An abutment plate is provided at one end of the extension rod near the precast tension pile. The extension rod is perpendicular to the abutment plate, and an insertion ring is provided on the abutment plate. The insertion ring and the limiting ring groove are inserted into each other.

[0017] By adopting the above technical solution, a plug-in ring is set on the contact plate, and a limiting ring groove is opened on the limiting plate parallel to the contact plate. When the extension rod is threadedly connected to the screw, the limiting ring gradually enters the limiting ring groove until it touches the bottom of the limiting ring groove, which has a limiting effect on the rotating extension rod, making it less likely for the extension rod to tilt and keeping it in a vertical state. This ensures that the extension rod, together with the precast anti-pull pile, only bears the vertical upward force, thus ensuring the accuracy of the test data.

[0018] Optionally, a reinforcing rib is provided between the extension rod and the contact plate.

[0019] By adopting the above technical solution, the reinforcing ribs on the contact plate support the extension rod, reducing the possibility of the extension rod tilting, and at the same time improving the connection strength between the extension rod and the contact plate.

[0020] Optionally, several reinforcing ribs are distributed around the circumference of the extension rod.

[0021] By adopting the above technical solution, several reinforcing ribs make the extension rod less prone to tilting, while further improving the connection strength between the extension rod and the contact plate.

[0022] On the other hand, the in-situ loading anti-tension pile construction method provided in this application adopts the following technical solution:

[0023] A construction method for in-situ loaded tension piles includes the following steps:

[0024] S1. Drive the precast tension piles into the ground. When the top of the pile is close to the ground, connect the extension rod to the connector.

[0025] S2. Continue to drive the precast tension pile downwards using the pile driving rod on the pile driver until the precast tension pile reaches the elevation, at which point the top of the extension rod will protrude from the ground.

[0026] S3. After the precast tension piles reach the elevation, pull out the pile driving rod, and then fill the pile hole with loose sand until it is level with the ground.

[0027] S4. Set up a static load test device for the pull-out of the foundation pile at the pile hole and connect the extension rod to the test device, and then conduct an in-situ loading test on the precast pull-out pile.

[0028] S5. After the test is completed, dismantle the pile pull-out static load test device and remove the extension rod;

[0029] S6. Backfill the pile hole to protect the precast pull-out pile.

[0030] By adopting the above technical solution, an extension rod is connected to the top of the precast tension pile, and then the extended rod exposed above ground is connected to the static load testing device for pile tension, eliminating the step of splicing the top of the precast tension pile. Therefore, there is no additional friction at the top of the precast tension pile due to splicing, resulting in accurate pile foundation bearing capacity data. Furthermore, there is no need to remove the spliced ​​portion of the precast tension pile, reducing construction costs and accelerating the construction progress.

[0031] Optionally, the pile pull-out static load test device described in step S4 includes a frame and a jack set between the frame and the ground. The frame has a gap for the extension rod to pass through. A connecting plate is detachably connected to the top of the frame. A connecting sleeve is provided at the bottom of the connecting plate. The connecting sleeve is threaded to the end of the extension rod.

[0032] By adopting the above technical solution, during the test, the frame connected to the prefabricated anti-tension piles was lifted upwards using jacks, and accurate pile bearing capacity data was obtained based on the force exerted by the jacks. The connecting sleeve was threaded onto the extension rod, thus ensuring the connection strength between the extension rod and the frame, while also ensuring a convenient and reliable connection.

[0033] Optionally, a plurality of studs are vertically arranged on the frame, the studs are movably passed through the connecting plate and connected to the locking nut, and a support sleeve is sleeved on the outside of the studs, the support sleeve being located between the frame and the connecting plate.

[0034] By adopting the above technical solution, the connecting plate is supported by the support sleeve, thus supporting the connecting plate even when there is a gap between the connecting plate and the frame. Moreover, different lengths of support sleeves can be selected according to the distance between the connecting plate and the frame, reducing the possibility of deformation of the connecting plate after tightening the lock nut.

[0035] In summary, this application includes at least one of the following beneficial technical effects:

[0036] 1. During construction, precast tension piles with connectors are driven into the ground. When the top of the precast tension pile is close to the ground surface, an extension rod is connected to the connector. The precast tension pile is then driven to the specified elevation, and the pile hole is filled with loose sand. A static load testing device for pile tension is then erected at the pile hole, and the extension rod is connected to the device for testing. After the test, the extension rod is removed, and the pile hole is backfilled to complete the construction. Since there is no additional friction from the splice at the top of the precast tension pile, and the friction between the extension rod and the sand is negligible, accurate pile bearing capacity data can be obtained. There is no need to remove the splice portion of the precast tension pile, reducing construction costs and accelerating the construction progress.

[0037] 2. A plug-in ring is set on the contact plate, and a limiting ring groove is opened on the limiting plate parallel to the contact plate. When the extension rod is threadedly connected to the screw, the limiting ring gradually enters the limiting ring groove until it touches the bottom of the limiting ring groove, which has a limiting effect on the rotating extension rod, making it less likely to tilt and keeping it in a vertical state. This ensures that the extension rod connected to the precast pull-out pile only bears the vertical upward force, thus ensuring the accuracy of the test data.

[0038] 3. By connecting an extension rod to the top of the precast tension pile and then connecting the exposed extension rod to the static load testing device for pile tension, the step of splicing the top of the precast tension pile is eliminated. Therefore, there is no additional friction at the top of the precast tension pile due to splicing, resulting in accurate pile foundation bearing capacity data. Furthermore, it eliminates the need to remove the spliced ​​portion of the precast tension pile, reducing construction costs and accelerating the construction progress. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of this application.

[0040] Figure 2 This is a schematic diagram illustrating the limiting rib structure in Embodiment 1 of this application.

[0041] Figure 3 This is a schematic diagram illustrating the structure of the static load test device for pile pull-out resistance in Embodiment 1 of this application.

[0042] Figure 4 This is a schematic diagram of the overall structure of Embodiment 2 of this application.

[0043] Figure 5 This is a schematic diagram illustrating the mating structure of the insertion ring and the limiting ring groove in Embodiment 2 of this application.

[0044] Explanation of reference numerals in the attached figures:

[0045] 1. Precast anti-tension pile; 2. Screw rod; 21. Limiting arc groove; 3. Extension rod; 4. Reinforcing cage; 41. Limiting bar; 5. Limiting plate; 51. Limiting ring groove; 6. Contact plate; 61. Insertion ring; 62. Reinforcing rib; 71. Frame; 72. Jack; 73. Connecting plate; 731. Connecting sleeve; 74. Stud; 741. Locking nut; 742. Support sleeve. Detailed Implementation

[0046] The following is in conjunction with the appendix Figure 1-5 This application will be described in further detail.

[0047] Example 1

[0048] This application discloses an in-situ loaded pull-out pile.

[0049] Reference Figure 1and Figure 2 An in-situ loaded tension pile includes a precast tension pile 1, with a reinforcing cage 4 and a connector pre-embedded inside. The connector extends beyond the center of the top of the precast tension pile 1. An extension rod 3 is detachably connected to the connector. During construction, the precast tension pile 1 is first driven into the ground until the top of the pile is slightly above the ground level. Then, the extension rod 3 is connected to the connector, and the precast tension pile 1 is driven to the desired elevation. Loose sand is then filled into the pile hole. At this point, a static load test device for pile tension is set up at the pile hole. The top of the extension rod 3 is connected to the static load test device for pile tension to conduct the test. After the test is completed, the extension rod 3 is removed, and the pile hole is backfilled to complete the construction.

[0050] Reference Figure 1 Since the top of the precast tension pile 1 does not require splicing, there is no additional friction on the upper part of the precast tension pile 1, and the friction between the extension rod 3 and the sand is extremely small and negligible, thus allowing for accurate pile foundation bearing capacity data to be obtained. At the same time, eliminating the need for splicing and chiseling reduces construction costs and accelerates the construction progress.

[0051] Reference Figure 1 and Figure 2 The connector is a rod or screw with a flange, which facilitates connection with other components. In this embodiment, the connector is a screw 2. After the precast tension pile 1 is formed, the thread on the surface of the screw 2 increases the connection stability between the screw 2 and the precast tension pile 1, making it less likely for the screw 2 to detach from the precast tension pile 1. The screw 2 is set along the length of the precast tension pile 1 and is located at the top of the precast tension pile 1. One end of the screw 2 is connected to the reinforcing cage 4, and the other end extends out of the top of the precast tension pile 1.

[0052] Reference Figure 1 and Figure 2 To further improve the stability of the screw rod 2, two limiting ribs 41 perpendicular to the screw rod 2 are installed on the reinforcing cage 4. The screw rod 2 is located between the two limiting ribs 41, and the ends of the limiting ribs 41 are tied to the reinforcing cage 4. A limiting arc groove 21 is opened on the screw rod 2 near each limiting rib 41, and part of the limiting rib 41 is embedded in the limiting arc groove 21. By embedding part of the limiting rib 41 into the limiting arc groove 21, the limiting rib 41 plays an axial limiting role for the screw rod 2, making the connection between the screw rod 2 and the precast tension pile 1 more reliable.

[0053] Reference Figure 1 and Figure 2 In this embodiment, the end of the extension rod 3 is hollow and is threadedly connected to the screw 2. The threaded connection has the advantages of being simple, convenient and strong. The screw 2 and the extension rod 3 are connected by the interlocking of the threads, which makes the screw 2 and the extension rod 3 less likely to loosen.

[0054] The implementation principle of an in-situ loaded tension pile in this application embodiment is as follows: During construction, the precast tension pile 1 is first driven into the ground. When the top of the precast tension pile 1 is slightly higher than the ground, the driving of the pile is stopped, and the extension rod 3 is threaded onto the screw rod 2. Then the driving of the pile continues until the precast tension pile 1 reaches the elevation, and then the pile hole is filled with loose sand.

[0055] Then, a static load test device for pile pull-out was set up at the pile hole, and the extension rod 3 was connected to the static load test device for pile pull-out to conduct the test. After the test was completed, the static load test device for pile pull-out and the extension rod 3 were removed, and the pile hole was backfilled with soil.

[0056] This application also discloses a construction method for in-situ loaded anti-uplift piles.

[0057] A construction method for in-situ loaded tension piles includes the following steps:

[0058] S1. Drive the precast anti-tension pile 1 into the ground. When the top of the pile is close to the ground, thread the extension rod 3 onto the screw rod 2.

[0059] S2. Continue to drive the precast tension pile 1 downward using the pile driving rod on the pile driver until the precast tension pile 1 reaches the elevation. At this time, the top of the extension rod 3 will be exposed above the ground.

[0060] S3. After the precast anti-tension pile 1 reaches the elevation, pull out the pile driving rod, and then fill the pile hole with loose sand until it is level with the ground.

[0061] S4. Set up a static load test device for the pull-out of the foundation pile at the pile hole, connect the extension rod 3 to the test device, and then conduct an in-situ loading test on the precast pull-out pile 1.

[0062] Reference Figure 3 The static load test device for pile pull-out includes a frame 71 and jacks 72. The frame 71 is horizontally positioned at the pile hole and is square in shape. One jack 72 is located at each of the four corners of the bottom of the frame 71. The jacks 72 are placed on the ground, with their piston rods contacting the frame 71. A connecting plate 73 is horizontally placed above the frame 71, and a connecting sleeve 731 is fixedly installed at the bottom of the connecting plate 73. The connecting sleeve 731 is vertically positioned and threadedly connected to the top of the extension rod 3. Several studs 74 are vertically installed on the frame 71 and are fixedly connected to the frame 71. The studs 74 movably pass through the connecting plate 73 and are connected to locking nuts 741. A support sleeve 742 is fitted around the studs 74, located between the frame 71 and the connecting plate 73.

[0063] S5. After the test is completed, remove the pile pull-out static load test device and rotate the extension rod 3 in the opposite direction until it can be removed.

[0064] S6. Backfill the pile hole to protect the precast pull-out pile 1.

[0065] The implementation principle of an in-situ loading anti-tension pile construction method is as follows: First, an extension rod 3 is connected to the top of the precast anti-tension pile 1. After the precast anti-tension pile 1 is constructed to the specified elevation, the extension rod 3 exposed above the ground is connected to the pile anti-tension static load testing device for testing. This eliminates the need for splicing the pile at the top of the precast anti-tension pile 1. This method not only yields accurate pile foundation bearing capacity data but also eliminates the need for splicing and chiseling, reducing construction costs and accelerating the construction progress.

[0066] Example 2

[0067] Reference Figure 4 and Figure 5 The difference between this embodiment and Embodiment 1 is that a limiting plate 5 is fixedly installed on the top of the precast tension pile 1. The limiting plate 5 is integrally formed with the precast tension pile 1, and a limiting annular groove 51 is formed on the side of the limiting plate 5 away from the precast tension pile 1. The center of the limiting annular groove 51 coincides with the axis of the extension rod 3. An abutment plate 6 is fixedly connected to the end of the extension rod 3 near the limiting plate 5. The extension rod 3 and the abutment plate 6 are arranged perpendicularly, and a reinforcing rib 62 is fixedly installed between the extension rod 3 and the abutment plate 6. Several reinforcing ribs 62 are distributed around the circumference of the extension rod 3. An insertion ring 61 is fixedly installed on the abutment plate 6, and the insertion ring 61 and the limiting annular groove 51 are inserted into each other.

[0068] The implementation principle of Example 2 is as follows: When the extension rod 3 is threadedly connected to the screw 2, the insertion ring 61, which is coaxially arranged with the extension rod 3, will gradually enter the limiting ring groove 51. The limiting ring groove 51, which is coaxial with the extension rod 3, limits the insertion ring 61, thereby limiting the extension rod 3, making it less likely for the extension rod 3 to tilt during rotation, keeping it in a vertical state, and ensuring the accuracy of the test data.

[0069] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. An in-situ loaded tension pile, characterized in that: The system includes a precast tension pile (1), in which a connector parallel to the pile body is embedded, the connector being a screw rod (2) located at the center of the pile top, the screw rod (2) extending beyond the pile top, a reinforcing cage (4) embedded inside the precast tension pile (1), two limiting ribs (41) arranged parallel to each other on the reinforcing cage (4), the limiting ribs (41) being perpendicular to the screw rod (2), the screw rod (2) being located between the two limiting ribs (41), a limiting arc groove (21) being formed on the screw rod (2), and the limiting ribs (41) being partially embedded inside the limiting arc groove (21); an extension rod (3) is detachably connected to the screw rod (2), the extension rod (3) The precast anti-tension pile (1) is hollow at the end and threadedly connected to the screw (2). A limiting plate (5) is provided at the top of the pile. A limiting ring groove (51) is opened on the limiting plate (5). The center of the limiting ring groove (51) coincides with the axis of the extension rod (3). A contact plate (6) is provided at one end of the extension rod (3) near the precast anti-tension pile (1). A plug ring (61) is provided on the contact plate (6). The plug ring (61) and the limiting ring groove (51) are plugged in. Several reinforcing ribs (62) are provided between the extension rod (3) and the contact plate (6) in the circumferential direction of the extension rod (3). After the precast anti-tension pile (1) is driven into the ground, the end of the extension rod (3) is higher than the ground.

2. A construction method for an in-situ loaded tension pile as described in claim 1, characterized in that, The process includes the following steps: S1, driving the precast tension pile (1) into the ground. When the top of the pile is close to the ground, thread the extension rod (3) onto the screw rod (2); S2, using the pile driving rod on the pile driver, continue to drive the precast tension pile (1) downward until the precast tension pile (1) reaches the elevation, at which point the top of the extension rod (3) protrudes from the ground; S3, after the precast tension pile (1) reaches the elevation, pull out the pile driving rod, and then fill the pile hole with loose sand until it is level with the ground; S4, setting up a static load test device for the tension pile at the pile hole. The static load test device for the tension pile includes a frame (71) and a jack (72) set between the frame (71) and the ground. The frame (71) has a gap for the extension rod (3) to pass through. A connecting plate (73) is detachably connected to the top of the frame (71). A connecting sleeve (731) is provided at the bottom, and the connecting sleeve (731) is threaded to the end of the extension rod (3). Several studs (74) are vertically provided on the frame (71). The studs (74) are movably passed through the connecting plate (73) and connected to the locking nut (741). A support sleeve (742) located between the frame (71) and the connecting plate (73) is sleeved on the outside of the studs (74). The extension rod (3) is connected to the test device, and then the precast anti-tension pile (1) is subjected to an in-situ loading test. S5. After the test is completed, the pile anti-tension static load test device is removed and the extension rod (3) is unloaded. S6. The pile hole is backfilled to protect the precast anti-tension pile (1).

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