A screw pile body strain gauge installation auxiliary device and installation method

Abstract

The application relates to the technical field of screw pile composite foundation testing, in particular to a screw pile body strain gauge installation auxiliary device and a method, the auxiliary device comprises a sleeve and an installation rod capable of being inserted into the sleeve, one end of the sleeve is provided with a sealing head, the sealing head is rotationally connected with the sleeve so that the sealing head can be opened or closed, and the strain gauge is arranged on the installation rod, so that the strain gauge can be conveniently installed into the screw pile, and the screw pile can be conveniently and deeply researched.

Description

Technical Field

[0001] This application relates to the field of testing technology for screw pile composite foundations, and in particular to an auxiliary device and method for installing screw pile strain gauges. Background Technology

[0002] Screw pile composite foundation, also known as screw pile composite foundation, is a new type of composite foundation that has been developed in recent years. Similar to traditional composite foundations, it consists of screw-shaped piles with relatively high stiffness and soil between the piles with relatively low stiffness, which jointly bear the upper load. It has advantages such as high bearing capacity and convenient construction, and is now widely used in practical engineering.

[0003] The existing main construction process for screw piles is as follows: drilling rig positioning → drilling rod hole formation → drilling rig stopping (drilling stops when the drilling depth reaches the design requirements) → grouting and pipe pulling.

[0004] The above-mentioned technical solution has the following drawbacks: In order to facilitate people to understand the distribution characteristics of the axial force and side resistance of the pile under the action of the upper load in actual engineering, strain gauges need to be installed inside the screw pile. However, the forming process of the above-mentioned screw pile makes the installation of strain gauges difficult, which in turn limits the in-depth study of the stress condition of the screw pile. Summary of the Invention

[0005] This application provides an auxiliary device and method for installing strain gauges in screw piles to facilitate the installation of strain gauges inside the piles and to enable in-depth research on the piles.

[0006] The above-mentioned technical objective of this application is achieved through the following technical solution:

[0007] An auxiliary device for installing a strain gauge on a screw pile includes a sleeve and an installation rod that can be inserted into the sleeve. One end of the sleeve is provided with a sealing head, which is rotatably connected to the sleeve so that the sealing head can be opened or closed. The strain gauge is mounted on the installation rod.

[0008] By adopting the above scheme, strain gauges need to be installed inside the screw pile. First, a sleeve with a sealing head is inserted into the freshly poured pile. After the sleeve descends to the preset elevation of the pile, the installation rod with the strain gauge is inserted into the sleeve. Then, the sleeve is lifted upwards, and the sealing head will open under the squeezing action of the lower end of the installation rod. Finally, the lower end of the installation rod will pass through the lower port of the sleeve. Continue to lift the sleeve upwards until the sleeve is completely detached from the pile. Finally, wait for the screw pile to reach its design strength, and then use a load test to determine the stress and strain at each measuring point, and calculate the axial force and side resistance of the pile. This achieves the goal of conveniently installing strain gauges inside the screw pile, thereby enabling in-depth research on screw pile composite foundations.

[0009] Preferably, a torsion spring is fitted on the rotating shaft between the sealing head and the sleeve to keep the sealing head in a closed state.

[0010] By adopting the above scheme, when the casing is lowered, the torsion spring can keep the sealing head closed, which can reduce the amount of concrete entering the casing and reduce the possibility of the strain gauge being damaged by the pressure of the concrete. After the installation rod is pressed against the sealing head, the installation rod can overcome the elastic force of the torsion spring to open the sealing head, so that the device can be used normally.

[0011] Preferably, the length of the mounting rod is greater than or equal to the depth of the screw pile.

[0012] By adopting the above scheme, the length of the mounting rod is relatively large, which can ensure that the mounting rod can fill the screw pile body, thereby enabling a comprehensive test of the stress on the screw pile body.

[0013] Preferably, an annular temporary storage box is fitted on the outer side of the sleeve, the volume of the temporary storage box is greater than or equal to the volume of the sleeve, the lower surface of the temporary storage box has multiple inlet holes, and the upper surface of the temporary storage box has an exhaust hole.

[0014] By adopting the above scheme, during the casing descent, the freshly poured concrete has a certain fluidity, so it will flow to the outside of the pile body as the casing is inserted. When the temporary storage box contacts the concrete surface, the concrete will pass through the manhole and enter the temporary storage box. When the casing is subsequently removed from the pile body, the concrete inside the temporary storage box will also flow back into the pile body at the manhole. The temporary storage box can reduce concrete waste, and the vent on the temporary storage box can allow external concrete to smoothly enter the temporary storage box.

[0015] Preferably, a fixing ring is fitted on the outer surface of the temporary storage box, the outer diameter of the fixing ring is larger than the inner diameter of the screw pile body, and a fixing bolt is provided on the fixing ring.

[0016] By adopting the above scheme, after the casing is completely lowered into the pile body, the fixing ring can be fixed to the ground with fixing bolts. The fixing ring can fix the position of the casing. Then, the installation rod is inserted into the casing. The setting of fixing ring and fixing bolt can reduce the manpower required for the use of installation auxiliary devices and make the use of installation auxiliary devices more convenient.

[0017] Preferably, a sliding block is provided on the inner surface of the temporary storage box, the sliding block is embedded in the inner surface of the outer surface of the sleeve, and a clearance groove is provided on the outer surface of the sleeve for the sliding block to reciprocate along the central axis of the sleeve.

[0018] By adopting the above scheme, the temporary storage box can be moved back and forth along the central axis of the sleeve by the sliding block. After the sealing head has just entered the screw pile body, the temporary storage box can be moved towards the sealing head. In this way, the overflowing concrete that may occur when the sleeve and sealing head enter the screw pile body will enter the temporary storage box. After the sleeve is fully entered into the screw pile body, the same volume of concrete will also enter the temporary storage box, which can further reduce the loss of concrete.

[0019] Preferably, the temporary storage box has multiple observation holes on its side wall, and the observation holes are fitted with sealed glass. A scale groove is provided on the side wall of the temporary storage box and on one side of the observation hole.

[0020] By adopting the above method, after the casing is fully inserted into the screw pile body, a large amount of concrete will enter the temporary storage box. By observing the liquid level at multiple observation holes, people can determine whether the casing is in a vertical state. This makes it easier to control the verticality of the installation rod that is about to be inserted into the casing.

[0021] Preferably, the sleeve is provided with multiple limiting plates inside, the limiting plates are coaxial with the sleeve, the multiple limiting plates are arranged sequentially along the central axis of the sleeve, and the limiting plates are provided with through holes for the mounting rod and the strain gauge on the mounting rod to pass through.

[0022] By adopting the above scheme, when the installation rod is inserted into the casing, the installation rod will pass through the through hole on the limiting plate. When the casing is in a vertical state, the limiting plate can also ensure that the installation rod is in a vertical state, which can improve the accuracy of the pile stress test data.

[0023] Preferably, an annular buoyancy plate is fitted onto the mounting rod, and the buoyancy plate is detachably connected to the mounting rod. Multiple levels are embedded on the upper surface of the buoyancy plate.

[0024] By adopting the above method, after the installation rod is completed, the outer sleeve will be removed. At this time, the buoyancy plate can be put on the upper end of the installation rod. The buoyancy plate is located above the concrete. Then, people can observe the position of the bubbles of multiple levels on the surface of the buoyancy plate to determine whether the level is horizontal. By observing the state of the level, people can determine whether the installation rod is vertical.

[0025] This application provides a method for installing a strain gauge on a screw pile, comprising the following steps:

[0026] S1. Move the sleeve with the sealing head installed to the vicinity of the top of the newly poured screw pile, and move the temporary storage box to a position close to the sealing head.

[0027] S2. Gradually insert the sleeve and sealing head into the screw pile body until the sleeve and sealing head descend to the design elevation of the screw pile body.

[0028] S3. Insert the mounting rod with the strain gauge installed longitudinally into the sleeve until the lower end of the mounting rod abuts against the sealing head;

[0029] S4. Move the sleeve upwards, and the lower end of the installation rod passes through the lower port of the sleeve. Continue to move the installation rod downwards until the installation rod descends to the design elevation of the screw pile body.

[0030] S5. Continue moving the sleeve upwards until the sleeve and sealing head are completely detached from the top of the screw pile.

[0031] S6. Place the buoyancy plate onto the mounting rod, and use the buoyancy plate to determine and adjust the verticality of the mounting rod.

[0032] S7. Once the screw pile body has fully reached its design strength, use load tests to determine the stress and strain at each measuring point, and calculate the axial force and side resistance of the pile body.

[0033] In summary, this application has the following technical effects:

[0034] 1. By setting up a strain gauge installation auxiliary device, after the screw pile body is poured, the auxiliary device can facilitate the installation of strain gauges into the pile body, which can facilitate in-depth research on screw pile composite foundations.

[0035] 2. By setting up a temporary storage box, when the sleeve is inserted into the pile body, the overflowing concrete will enter the temporary storage box. After the sleeve is removed from the pile body, the concrete in the temporary storage box will flow back into the pile body. The setting of the temporary storage box can reduce concrete waste.

[0036] 3. By setting up a buoyancy plate, when the casing is removed from inside the pile, the buoyancy plate is placed on the installation rod. People can judge whether the installation rod is in a vertical state by the level on the buoyancy plate, which can ultimately improve the accuracy of the test data. Attached Figure Description

[0037] Figure 1 This is an overall structural diagram of the strain gauge installation auxiliary device in use according to the embodiments of this application;

[0038] Figure 2 This is a longitudinal sectional view of the strain gauge installation auxiliary device in use in the embodiments of this application (the shaded area in the figure is the ground);

[0039] Figure 3 This is a partial view of the connection between the sleeve and the sealing head in an embodiment of this application;

[0040] Figure 4 This is a cross-sectional view of the strain gauge installation auxiliary device in use in the embodiments of this application (the shaded area in the figure is the ground, and the black arrow points to the direction of movement of the sleeve).

[0041] Figure 5 This is a diagram showing the state of the casing after it has been removed from the pile body in this embodiment of the application.

[0042] In the diagram, 1. Sleeve; 11. Limiting plate; 12. Through hole; 2. Mounting rod; 21. Buoyancy plate; 3. Sealing head; 4. Torsion spring; 5. Pile body; 6. Strain gauge; 7. Temporary storage assembly; 71. Temporary storage box; 72. Fixing ring; 73. Fixing bolt; 74. Sliding block; 75. Vent hole; 76. Leaving groove; 77. Sealing glass; 78. Scale groove; 8. Level. Detailed Implementation

[0043] The present application will be further described in detail below with reference to the accompanying drawings.

[0044] Reference Figures 1-3 This application provides an auxiliary device for installing strain gauges on a screw pile, including a sleeve 1, an installation rod 2, a sealing head 3, and a torsion spring 4. The length of the sleeve 1 is equal to the depth of the screw pile body 5. The sealing head 3 is hemispherical in shape and is located at one end of the sleeve 1 and is rotatably connected to the sleeve 1. The torsion spring 4 is located on the hinge shaft between the sleeve 1 and the sealing head 3 and can drive the sealing head 3 to seal one end of the sleeve 1. In this embodiment, the installation rod 2 is made of steel bar and its length is greater than the depth of the screw pile body 5. Multiple strain gauges 6 are provided and are distributed sequentially along the length direction of the installation rod 2, and the connecting line formed by the multiple strain gauges 6 is threaded.

[0045] Combined Figure 4 When installing strain gauges 6 inside the screw pile body 5, first insert the sleeve 1 with the sealing head 3 into the freshly poured pile body 5. After the sleeve 1 descends to the preset elevation of the pile body 5, insert the installation rod 2 with the strain gauge 6 into the sleeve 1. Then lift the sleeve 1 upwards. The sealing head 3 will open under the squeezing action of the lower end of the installation rod 2. Finally, the lower end of the installation rod 2 will pass through the lower port of the sleeve 1. Continue to lift the sleeve 1 upwards until the sleeve 1 is completely detached from the pile body 5. Finally, wait for the screw pile body 5 to reach the design strength, and then use load tests to determine the stress and strain at each measuring point, and calculate the axial force and side resistance of the pile. This achieves the effect of facilitating the installation of strain gauges 6 inside the screw pile and facilitating in-depth research on the screw pile.

[0046] Reference Figure 1 and Figure 2The sleeve 1 with the sealing head 3 has a certain volume. After the sleeve 1 is inserted into the screw pile body 5, some of the previously poured concrete will overflow. In order to reduce the waste of concrete, a temporary storage component 7 for collecting concrete is provided on the sleeve 1.

[0047] The temporary storage assembly 7 includes a temporary storage box 71, a fixing ring 72, a fixing bolt 73, and a sliding block 74. The internal volume of the temporary storage box 71 is equal to the overall volume of the sleeve 1 and the sealing head 3. Multiple inlet holes are provided on the lower surface of the temporary storage box 71 along the circumferential direction, and an exhaust hole 75 is provided on the upper surface of the temporary storage box 71. The fixing ring 72 is sleeved on the outside of the temporary storage box 71, and the outer diameter of the fixing ring 72 is larger than the inner diameter of the screw post body 5. The fixing bolt 73 is set on the fixing ring 72. The sliding block 74 is set on the inner surface of the temporary storage box 71 and is embedded in the outer surface of the sleeve 1. A clearance groove 76 for the reciprocating movement of the sliding block 74 is provided on the outer surface of the sleeve 1 along the central axis direction of the sleeve 1.

[0048] The temporary storage box 71 can be moved back and forth along the central axis of the sleeve 1 by the sliding block 74. After the sealing head 3 has just entered the screw pile body 5, the temporary storage box 71 can be moved towards the sealing head 3 until the fixing ring 72 on the temporary storage box 71 abuts the ground. Then, the fixing bolt 73 is used to fix the position of the fixing ring 72 and the temporary storage box 71. During the process of lowering the sleeve 1, the sleeve 1 and the sealing head 3 may cause the overflowing concrete to enter the temporary storage box 71 when they enter the screw pile body 5. After the sleeve 1 is fully entered into the screw pile body 5, the same volume of concrete will also enter the temporary storage box 71, thus reducing the loss of concrete.

[0049] After the sleeve 1 is lowered into the screw pile body 5, the installation rod 2 is placed inside the sleeve 1. The verticality of the sleeve 1 also affects the verticality of the installation rod 2. To facilitate judgment on whether the sleeve 1 is vertical, multiple observation holes are provided on the side wall of the temporary storage box 71. Sealed glass 77 is installed inside each observation hole. A graduated groove 78 is provided on the side wall of the temporary storage box 71, on one side of each observation hole. After the sleeve 1 is fully inserted into the screw pile body 5, a significant amount of concrete will enter the temporary storage box 71. By observing the liquid level at the multiple observation holes, it is possible to determine whether the sleeve 1 is vertical. This facilitates control over the verticality of the installation rod 2, which is about to be inserted into the sleeve 1. It should be noted that the temporary storage box 71 needs to be fixed on a level surface for more accurate judgment.

[0050] Reference Figure 2After the sleeve 1 is installed, in order to improve the accuracy of the mounting rod 2, multiple limiting plates 11 are set inside the sleeve 1. The limiting plates 11 are coaxial with the sleeve 1 and are arranged sequentially along the central axis of the sleeve 1. The limiting plates 11 have through holes 12 for the mounting rod 2 and the strain gauge 6 on the mounting rod 2 to pass through. When the mounting rod 2 is inserted into the sleeve 1, the mounting rod 2 will pass through the through hole 12 on the limiting plate 11. When the sleeve 1 is in a vertical position, the limiting plates 11 can also ensure that the mounting rod 2 is in a vertical position.

[0051] Reference Figure 5 After the installation rod 2 is completed, the outer sleeve 1 is removed. To keep the installation rod 2 vertical, an annular buoyancy plate 21 is fitted onto the installation rod 2. The buoyancy plate 21 is detachably connected to the installation rod 2, and multiple levels 8 are embedded in the upper surface of the buoyancy plate 21. After the sleeve 1 is removed, the buoyancy plate 21 is fitted onto the upper end of the installation rod 2. The buoyancy plate 21 is located above the concrete. People can then determine whether the levels 8 are level by observing the positions of the bubbles in the multiple levels 8 on the upper surface of the buoyancy plate 21. The state of the levels 8 indicates whether the installation rod 2 is vertical.

[0052] This application also provides a method for installing a strain gauge on a screw pile, including the following steps:

[0053] S1. Move the sleeve 1 with the sealing head 3 installed to the vicinity of the top of the newly poured screw pile body 5, and move the temporary storage box 71 to a position close to the sealing head 3.

[0054] S2. Move the temporary storage box 71 on the sleeve 1 until the temporary storage box 71 is moved close to the sealing head 3. Gradually insert the sleeve 1 and the sealing head 3 into the screw pile body 5 until the sleeve 1 and the sealing head 3 are lowered to the design elevation of the screw pile body 5. Repair and level the ground, tighten the fixing bolt 73 on the fixing ring 72 to fix the position of the temporary storage box 71.

[0055] S3. Insert the mounting rod 2, on which the strain gauge 6 is installed, longitudinally into the sleeve 1. At this time, it is necessary to ensure that the mounting rod 2 passes through the through hole 12 on the limiting piece 11 until the lower end of the mounting rod 2 abuts against the sealing head 3.

[0056] S4. Move the sleeve 1 upwards, and the lower end of the mounting rod 2 passes through the lower port of the sleeve 1. Continue to move the mounting rod 2 downwards until the mounting rod 2 descends to the design elevation of the screw pile body 5.

[0057] S5. Continue to move the sleeve 1 upwards until the sleeve 1 and the sealing head 3 are completely detached from the top of the screw pile.

[0058] S6. Fit the buoyancy plate 21 onto the mounting rod 2, and use the buoyancy plate 21 to determine and adjust the verticality of the mounting rod 2;

[0059] S7. When the screw pile body 5 reaches the design strength, use load tests to determine the stress and strain at each measuring point, and calculate the axial force and side resistance of the pile body.

[0060] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A screw pile shaft strain gauge installation aid characterised in that: The sleeve (1) includes a sleeve (1) and an installation rod (2) that can be inserted into the sleeve (1). One end of the sleeve (1) is provided with a sealing head (3), which is rotatably connected to the sleeve (1) so that the sealing head (3) can be opened or closed. A strain gauge (6) is provided on the installation rod (2). An annular temporary storage box (71) is sleeved on the outside of the sleeve (1). The volume of the temporary storage box (71) is greater than or equal to the volume of the sleeve (1). Multiple inlet holes are provided on the lower surface of the temporary storage box (71), and an exhaust hole (75) is provided on the upper surface of the temporary storage box (71). A sliding block (74) is provided on the inner surface of the temporary storage box (71), and the sliding block (74) is embedded in the outer surface of the sleeve (1). Inside, a clearance groove (76) is provided on the outer surface of the sleeve (1) for the sliding block (74) to reciprocate along the central axis of the sleeve (1); multiple observation holes are provided on the side wall of the temporary storage box (71), and a sealing glass (77) is provided inside the observation hole. A scale groove (78) is provided on the side wall of the temporary storage box (71) and on one side of the observation hole; multiple limiting pieces (11) are provided inside the sleeve (1), and the limiting pieces (11) are coaxial with the sleeve (1). The multiple limiting pieces (11) are arranged sequentially along the central axis of the sleeve (1). A through hole (12) is provided on the limiting piece (11) for the mounting rod (2) and the strain gauge (6) on the mounting rod (2) to pass through.

2. A screw pile body strain gauge installation aid according to claim 1, characterised in that: A torsion spring (4) is fitted on the rotating shaft between the sealing head (3) and the sleeve (1) to keep the sealing head (3) in a closed state.

3. A screw pile body strain gauge installation aid according to claim 1, characterised in that: The length of the mounting rod (2) is greater than or equal to the depth of the screw pile body (5).

4. A screw pile body strain gauge installation aid according to claim 1, characterised in that: A fixing ring (72) is fitted on the outer surface of the temporary storage box (71). The outer diameter of the fixing ring (72) is larger than the inner diameter of the screw pile body (5). A fixing bolt (73) is provided on the fixing ring (72).

5. A screw pile body strain gauge installation aid according to claim 1, characterised in that: An annular buoyancy plate (21) is fitted on the mounting rod (2). The buoyancy plate (21) is detachably connected to the mounting rod (2). Multiple levels (8) are embedded on the upper surface of the buoyancy plate (21).

6. A method for installing strain gauges on screw piles, using the auxiliary device for installing strain gauges on screw piles as described in claim 5, characterized in that... Includes the following steps: S1. Move the sleeve (1) with the sealing head (3) installed to the vicinity of the top of the newly poured screw pile body (5), and move the temporary storage box (71) to a position close to the sealing head (3). S2. Gradually insert the sleeve (1) and sealing head (3) into the screw pile body (5) until the sleeve (1) and sealing head (3) descend to the design elevation of the screw pile body (5); S3. Insert the mounting rod (2) with the strain gauge (6) longitudinally into the sleeve (1) until the lower end of the mounting rod (2) abuts against the sealing head (3); S4. Move the sleeve (1) upward, and the lower end of the mounting rod (2) passes through the lower port of the sleeve (1). Continue to move the mounting rod (2) downward until the mounting rod (2) descends to the design elevation of the screw pile body (5). S5. Continue to move the sleeve (1) upward until the sleeve (1) and the sealing head (3) are completely removed from the top of the screw pile; S6. Place the buoyancy plate (21) on the mounting rod (2), and determine and adjust the verticality of the mounting rod (2) through the buoyancy plate (21); S7. When the screw pile body (5) has fully reached the design strength, use load tests to determine the stress and strain at each measuring point, and calculate the axial force of the pile body and the pile side resistance.

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