Pile cap for static load test of foundation pile and use method of pile cap

Abstract

The invention provides a pile cap for a foundation pile static load test and a using method thereof.The pile cap comprises a pile barrel and a top plate, the top plate is arranged at the top of the pile barrel, and a foundation pile mounting cavity is formed in the pile barrel; a containing cavity used for containing low-melting-point metal is further formed in the pile barrel, the containing cavity and the foundation pile mounting cavity are arranged in the axial direction of the pile barrel, and the containing cavity is located above the foundation pile mounting cavity. An injection hole communicated with the accommodating cavity is formed in the top of the pile cap; the pile barrel is further provided with a heating piece, a discharge hole and a sealing piece, the discharge hole is communicated with the containing cavity and is close to the bottom of the containing cavity, the sealing piece is arranged at the discharge hole to open or close the discharge hole, and the heating piece is used for heating the low-melting-point metal in the containing cavity after the test is finished. The pile cap is simple in structure, convenient to disassemble and assemble, good in universality, high in economical efficiency, capable of reducing the risk of pile cap damage and high in test precision.

Description

Technical Field

[0001] The invention relates to the technical field of pile foundation detection, and in particular to a pile cap used for a pile foundation static load test and a use method thereof. Background Art

[0002] Pile foundations generally require static load testing, that is, placing a pressure block on the top of the pile foundation to test the vertical bearing capacity of the pile foundation. Traditional pile foundation static load testing, in order to prevent the pressure block from crushing the pile foundation, generally requires pouring a concrete pile cap on the pile foundation. After curing, the concrete pile cap solidifies and reaches the preset strength before the static load test can be carried out. During the test, the pressure block is placed on the concrete pile cap. When using this method for static load testing, since it takes many days to wait after the concrete pile cap is poured, the concrete pile cap needs to be forcibly removed after the static load test is completed, which is time-consuming and labor-intensive, and wastes concrete resources. Moreover, in the process of removing the concrete pile cap, the pile foundation may be accidentally damaged.

[0003] The utility model patent with publication number CN210712987U discloses a simple and recyclable static load test pile steel pile cap, in which the space between the end steel plate and the top plane of the foundation pile is filled with yellow sand. However, yellow sand has strong fluidity. During the static load test, the yellow sand exerts strong lateral pressure on the steel cylinder, which is easy to deform, causing the pile cap to be eccentric, affecting the test accuracy. It is necessary to use a steel plate with higher strength or thicker thickness to make the steel cylinder, which makes the steel pile cap heavier and increases the manufacturing and installation costs. Summary of the invention

[0004] The first object of the present invention is to provide a pile cap which can reduce the risk of pile cap damage and can be used for static load detection on foundation piles of various complex structures.

[0005] The second object of the present invention is to provide a method for using the pile cap.

[0006] In order to achieve the above first purpose, the pile cap for pile foundation static load test provided by the present invention comprises a pile barrel and a top plate, wherein the top plate is arranged on the top of the pile barrel, and a pile foundation installation cavity is arranged in the pile barrel; The pile barrel is also provided with a accommodating chamber for accommodating low-melting-point metals, the accommodating chamber and the foundation pile installation chamber are arranged along the axial direction of the pile barrel, and the accommodating chamber is located above the foundation pile installation chamber; the top of the pile cap is provided with an injection hole connected with the accommodating chamber; the pile barrel is also provided with a heating element, a discharge hole and a sealing element, the discharge hole is connected with the accommodating chamber and is arranged close to the bottom of the accommodating chamber, the sealing element is arranged at the discharge hole to open or close the discharge hole, and the heating element is used to heat the low-melting-point metal in the accommodating chamber after the test is completed.

[0007] As can be seen from the above, the present invention transmits pressure to the top of the foundation pile through the solidified low-melting-point metal. Even if there are protruding steel bars on the top of the foundation pile, the top of the foundation pile can still evenly receive the test pressure, effectively protecting the top of the foundation pile and the pile cap. Since the low-melting-point metal can solidify into a solid, it can avoid the problem of the existing yellow sand exerting a strong lateral pressure on the steel cylinder, causing the steel cylinder to deform, avoid stress concentration and damage to the pile cap, and can effectively ensure the accuracy of the test data. At the same time, there is no need to cut off the steel bars left on the top of the foundation pile, and there is no need to raise the foundation pile concrete, which greatly improves the efficiency of arranging the top of the foundation pile. And the low-melting-point metal can be used repeatedly, greatly reducing production costs.

[0008] A further solution is that the heating element is arranged on the inner wall of the accommodating cavity; and / or the injection hole is located on the top plate and penetrates the top plate along the thickness direction of the top plate; and / or the sealing element is detachably installed at the discharge hole.

[0009] As can be seen from the above, the heating element arranged on the inner wall of the pile barrel can effectively improve the heating efficiency of the low melting point metal in the accommodating cavity, thereby increasing the speed of removing the pile cap after the detection is completed.

[0010] In a further embodiment, the heating element extends along the circumference of the pile barrel.

[0011] As can be seen from the above, the heating element extends along the circumference of the pile barrel, and the heating element can evenly and fully heat the low-melting-point metal, greatly improving the work efficiency.

[0012] A further solution is that an ultrasonic vibration device is also provided on the outer wall of the pile tube, and the ultrasonic vibration device is arranged close to the accommodating cavity.

[0013] It can be seen from the above that when the low-melting-point metal liquid is injected, the ultrasonic vibration device discharges the gas in the liquid low-melting-point metal, thereby reducing the risk of cavitation.

[0014] A further solution is that the pile cap also includes a positioning member, which is arranged on the peripheral wall of the pile barrel, and a positioning end of the positioning member passes through the peripheral wall of the pile barrel and extends into the accommodating cavity, and the positioning end is located at one end of the accommodating cavity close to the foundation pile installation cavity.

[0015] As can be seen from the above, by means of the provided positioning pieces, the pile cap can be quickly installed on the top of the foundation pile, greatly improving the assembly efficiency.

[0016] A further solution is that the number of the positioning members is more than two, and the positioning members are arranged at intervals along the circumference of the pile barrel.

[0017] A further solution is that reinforcing ribs are provided on the outer wall of the pile tube, and the reinforcing ribs extend along the circumferential direction of the outer wall of the pile tube.

[0018] As can be seen from the above, the outer wall of the pile barrel is provided with reinforcing ribs, the reinforcing ribs extend along the circumference of the pile barrel, and the reinforcing ribs and the accommodating cavity are arranged opposite to each other in the radial direction of the pile barrel.

[0019] A further solution is that the top plate is detachably connected to the pile barrel, a first pile diameter step and a second pile diameter step are provided on the lower side of the top plate, the radius of the first pile diameter step is smaller than the radius of the second pile diameter step; the pile barrel can dock with the first pile diameter step or the second pile diameter step.

[0020] As can be seen from the above, the detachable connection between the top plate and the pile barrel can facilitate the disassembly and assembly of the pile cap, while the first pile diameter step and the second pile diameter step provided on the side of the top plate facing the pile barrel for docking with the pile barrel can be universally installed with pile barrels of various diameters, greatly improving the versatility.

[0021] A further solution is that a high temperature resistant sealing gasket is provided between the pile tube and the top plate.

[0022] In order to achieve the above second objective, a method for using the above pile cap is provided, the method comprising the following steps: The pile cap is installed on the top of the foundation pile, and the top of the foundation pile is located in the foundation pile installation cavity; low-melting-point metal liquid is injected into the accommodating cavity from the injection hole; after the low-melting-point metal is cooled into a solid, a static load test is performed; the low-melting-point metal is heated by the heating element, and after the low-melting-point metal is completely melted, the discharge hole is opened, and the low-melting-point metal is discharged from the discharge hole.

[0023] In summary, it can be seen that the pile cap of the present invention has a simple structure, is convenient to disassemble and assemble, has good versatility, is highly economical, can reduce the risk of damage to the pile cap, and has high test accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a three-dimensional diagram of a pile cap embodiment and a pile foundation used for a pile foundation static load test.

[0025] Figure 2 The cross-sectional view of a pile cap embodiment and a pile foundation used for a pile foundation static load test according to the present invention is shown.

[0026] Figure 3 It is a structural exploded view of a pile cap embodiment of the present invention for a static load test of a pile foundation. DETAILED DESCRIPTION

[0027] See also Figures 1 to 3The pile cap for static load test of foundation pile 9 provided in this embodiment includes a pile barrel 1, a positioning member 6 and a top plate 3, wherein the top plate 3 is arranged on the top of the pile barrel 1 and is detachably connected to the pile barrel 1. The pile cap is installed on the top of the foundation pile 9, and the pile barrel 1 extends along the axial direction of the foundation pile 9. A receiving chamber 4 and a pile installation chamber 5 are sequentially arranged in the pile cap from top to bottom. The top of the foundation pile 9 is located in the pile installation chamber 5. In this embodiment, the pile cap is made of metal. The receiving chamber 4 and the pile installation chamber 5 are arranged along the axial direction of the pile barrel 1, and the receiving chamber 4 is used to fill a low-melting-point metal. Preferably, the low-melting-point metal is lead, tin, tin alloy, aluminum alloy, etc., whose melting point is much lower than that of the metal used to make the pile cap.

[0028] The positioning member 6 is arranged on the peripheral wall of the pile barrel 1, and the positioning end 60 of the positioning member 6 passes through the peripheral wall of the pile barrel 1 and extends into the accommodating cavity 4. The positioning end 60 is located at one end of the accommodating cavity 4 close to the foundation pile installation cavity 5. The positioning member 6 is a positioning bolt, and the number of the positioning bolts is at least three. Each positioning bolt is arranged at intervals along the circumference of the pile barrel 1, and the positioning end 60 of each positioning bolt extends into the accommodating cavity 4. The foundation pile installation cavity 5 is located below the positioning end 60. The positioning end 60 is used to limit the position of the pile cap relative to the foundation pile 9 in the vertical direction.

[0029] An injection hole 7 is provided on the top plate 3, which penetrates the top plate 3 along the thickness direction of the top plate 3 and is connected with the accommodating chamber 4. A heating element 8, a discharge hole (not shown in the figure) and a sealing element 10 are provided on the pile tube 1. The discharge hole is connected with the accommodating chamber 4 and is arranged near the bottom of the accommodating chamber 4. The sealing element 10 is arranged at the discharge hole to open or close the discharge hole. In this embodiment, the sealing element 10 is a plug, which is detachably installed in the discharge hole. The heating element 8 is arranged corresponding to the accommodating chamber 4. Optionally, the injection hole 7 can also be arranged on the side wall of the accommodating chamber 4 and close to the top plate 3.

[0030] Preferably, the heating element 8 is embedded in the inner wall of the accommodating cavity 4 and is located above the positioning element 6. The heating element 8 extends along the circumferential direction of the inner wall of the pile barrel 1. The number of the heating elements 8 is at least two, and a plurality of heating elements 8 can be arranged along the axial direction of the pile barrel 1. The heating element 8 includes a copper ring, and when installed on the inner wall of the pile barrel 1 made of metal, the outer side of the copper ring is wrapped with an insulating layer. Optionally, the heating element 8 can also be a heating tube, carbon fiber wire, etc.

[0031] The outer wall of the pile barrel 1 is also provided with an ultrasonic vibration device 2 and a reinforcing rib 11, the reinforcing rib 11 and the accommodating cavity 4 are arranged opposite to each other in the radial direction of the pile barrel 1, the ultrasonic vibration device 2 and the accommodating cavity 4 are arranged correspondingly in the radial direction of the pile barrel 1, and the reinforcing rib 11 extends along the circumferential direction of the outer wall of the pile barrel 1. The number of the reinforcing ribs 11 may be more than two, and more than two reinforcing ribs 11 are arranged along the axial direction of the pile barrel 1.

[0032] A first pile diameter step 12 and a second pile diameter step 13 for docking with the pile barrel 1 are provided on one side of the top plate 3 facing the pile barrel 1, and the radius of the first pile diameter step 12 is smaller than the radius of the second pile diameter step 13. The first pile diameter step 12 is docked with the pile barrel 1. A high temperature resistant sealing gasket 14 is provided between the pile barrel 1 and the top plate 3. Optionally, the sealing gasket 14 is sleeved outside the first pile diameter step 12 and is squeezed between the top wall of the pile barrel 1 and the lower surface of the top plate 3. Preferably, the elastic modulus of the sealing gasket 14 is smaller than the elastic modulus of the low melting point metal in the solid state, so as to reduce the shear force along the axial direction of the pile body on the positioning member 6.

[0033] The present invention also provides a method for using the pile cap. The method comprises the following steps: Step 1: chisel off the low-strength layer on the top of the foundation pile 9 and level the top surface of the foundation pile 9 by using a subtractive method; If there is steel bar left on the top of the foundation pile 9, there is no need to cut it off.

[0034] Step 2: Screw the positioning bolts into the receiving cavity 4 of the pile barrel 1, install the pile barrel 1 on the top of the foundation pile 9, install the top plate 3 on the top of the pile barrel 1, the top of the foundation pile 9 is located in the foundation pile installation cavity 5, and the positioning ends 60 of at least part of the positioning bolts are in contact with the top wall of the foundation pile 9; Preferably, after the pile barrel 1 is installed on the top of the foundation pile 9, a caulking agent is filled at the junction of the pile barrel 1 and the top surface of the foundation pile 9. The caulking agent is preferably made of inorganic materials, which can be ordinary glass glue, etc. After the liquid metal contacts the glass glue, the glass glue is rapidly carbonized, and the glass glue still has good resistance after carbonization. Even without the caulking agent, the liquid metal quickly cools down after contacting the pile barrel 1, which can also prevent the low-melting-point metal from continuously flowing into the gap.

[0035] Preferably, a release agent may be coated on the inner wall of the accommodating cavity 4 .

[0036] Step 3: injecting low-melting-point metal liquid into the containing cavity 4 from the injection hole 7, and starting the ultrasonic vibration device 2 when injecting the low-melting-point metal liquid to reduce the risk of cavitation; Step 4: After the low melting point metal is cooled into a solid, a static load test is performed; Step 5: After the static load test is completed, the low-melting-point metal is heated by the heating element 8. After it is completely melted, the discharge hole is opened and the low-melting-point metal liquid is discharged from the discharge hole.

[0037] In summary, the present invention transmits pressure to the top of the foundation pile through the solidified low-melting-point metal. Even if there are protruding steel bars on the top of the foundation pile, the top of the foundation pile can still evenly receive the test pressure, effectively protecting the top of the foundation pile and the pile cap. Since the low-melting-point metal can solidify into a solid, it can avoid the problem of the existing yellow sand exerting a strong lateral pressure on the steel cylinder, causing the steel cylinder to deform, avoid stress concentration and damage to the pile cap, and can effectively ensure the accuracy of the test data. At the same time, there is no need to cut off the steel bars left on the top of the foundation pile, and there is no need to raise the foundation pile concrete, which greatly improves the efficiency of arranging the top of the foundation pile. And the low-melting-point metal can be used repeatedly, greatly reducing production costs.

[0038] The above-described embodiments are only preferred examples of the present invention and are not intended to limit the scope of implementation of the present invention. Therefore, any equivalent changes or modifications made according to the structures, features and principles described in the scope of the patent application of the present invention should be included in the scope of the patent application of the present invention.

Claims

1. A pile cap for a static load test of a pile foundation, comprising a pile barrel and a top plate, wherein the top plate is arranged on the top of the pile barrel, and a pile foundation installation cavity is arranged in the pile barrel; Features: The pile barrel is also provided with a receiving cavity for receiving low melting point metal, the receiving cavity and the foundation pile installation cavity are arranged along the axial direction of the pile barrel, and the receiving cavity is located above the foundation pile installation cavity; The top of the pile cap is provided with an injection hole communicating with the accommodation cavity; The pile tube is also provided with a heating element, a discharge hole and a sealing element. The discharge hole is connected with the accommodating cavity and is arranged near the bottom of the accommodating cavity. The sealing element is arranged at the discharge hole to open or close the discharge hole. The heating element is used to heat the low-melting-point metal in the accommodating cavity after the test.

2. The pile cap for pile foundation static load test according to claim 1, characterized in that: The heating element is arranged on the inner wall of the accommodating cavity; and / or The injection hole is located on the top plate and penetrates the top plate along the thickness direction of the top plate; and / or The sealing member is detachably mounted at the discharge hole.

3. The pile cap for pile foundation static load test according to claim 2, characterized in that: The heating element extends along the circumference of the pile cylinder.

4. The pile cap for pile foundation static load test according to any one of claims 1 to 3, characterized in that: An ultrasonic vibration device is also provided on the outer wall of the pile tube, and the ultrasonic vibration device is arranged close to the accommodating cavity.

5. The pile cap for pile foundation static load test according to any one of claims 1 to 3, characterized in that: The pile cap also includes a positioning member, which is arranged on the peripheral wall of the pile barrel. The positioning end of the positioning member passes through the peripheral wall of the pile barrel and extends into the accommodating cavity. The positioning end is located at one end of the accommodating cavity close to the foundation pile installation cavity.

6. The pile cap for pile foundation static load test according to claim 5, characterized in that: The number of the positioning members is more than two, and the positioning members are arranged at intervals along the circumference of the pile barrel.

7. The pile cap for pile foundation static load test according to any one of claims 1 to 3, characterized in that: The outer wall of the pile barrel is provided with reinforcing ribs, the reinforcing ribs extend along the circumference of the pile barrel, and the reinforcing ribs and the accommodating cavity are arranged opposite to each other in the radial direction of the pile barrel.

8. The pile cap for pile foundation static load test according to any one of claims 1 to 3, characterized in that: The top plate is detachably connected to the pile barrel, a first pile diameter step and a second pile diameter step are provided on the lower side of the top plate, and the radius of the first pile diameter step is smaller than the radius of the second pile diameter step; The pile barrel can be docked with the first pile diameter step or the second pile diameter step.

9. The pile cap for pile foundation static load test according to claim 8, characterized in that: A high temperature resistant sealing gasket is arranged between the pile tube and the top plate.

10. A method for using a pile cap, characterized in that: The pile cap for pile foundation static load test according to any one of claims 1 to 9 above, the method comprises the following steps: The pile cap is installed on the top of the foundation pile, and the top of the foundation pile is located in the foundation pile installation cavity; Injecting low melting point metal liquid into the containing cavity from the injection hole; After the low melting point metal is cooled into a solid, a static load test is performed; The low melting point metal is heated by the heating element, and after the low melting point metal is completely melted, the discharge hole is opened, and the low melting point metal is discharged from the discharge hole.

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