Post-implanted post-tensioned large pipe pile axial force testing device and testing method

Abstract

The present invention discloses a post-implanted post-tensioned large pipe pile axial force testing device and testing method, including a post-tensioned large pipe pile formed by splicing several sections of concrete pipe piles; two symmetrically distributed metal pipes are pre-installed at the center of the pipe wall of each section of concrete pipe pile; after several sections of concrete pipe piles are spliced, the metal pipes of adjacent concrete pipe piles are spliced ​​to form a through sensor installation channel, and a Bragg fiber grating strain sensor is provided in the sensor installation channel; the optical fiber wire connected to the Bragg fiber grating strain sensor extends from the optical fiber wire guide port to connect to the fiber grating demodulator; the sensor installation channel is densely filled with grouting agent; and a calibrated section sensor is pre-buried near the top of the pile. The present invention improves the survival rate and accuracy of the sensor; optimizes the strain test effect; the process of post-grouting of the hole not only protects the sensor, but also improves the installation efficiency and effect of the sensor, and improves the correctness and accuracy of the axial force test.

Description

Technical Field

[0001] The invention relates to the technical fields of port engineering and pile foundation engineering, and in particular to a post-implanted post-tensioned prestressed large pipe pile body axial force testing device and a testing method. Background Art

[0002] The main purpose of static load pile test of high-pile wharf is to test the total bearing capacity of pile foundation and the lateral friction and end resistance of soil layer. The test results are used to verify the design bearing capacity and optimize the design, which is very important. Among them, the lateral friction and end resistance of soil layer are mainly achieved by testing the segmented axial force of pile body.

[0003] At present, large-scale port engineering high-pile docks have gradually begun to promote the use of post-tensioned prestressed concrete large pipe piles. This type of pile has the advantages of low cost, high tensile strength of the pile body, and high durability. The post-tensioned prestressed concrete large pipe pile, the pile diameter is generally 1.2m or 1.4m, and multiple pile sections are connected into a longer pile body after being tensioned by steel strands. The length of a single section does not exceed 10m. During the preparation process, the single-section pile body is subjected to high-speed rotation and high-temperature steam curing to form a single-section pipe section with a strength level of C60 or above. Multiple single-section piles are bonded with adhesives, tensioned, grouting, and tensioned to form a complete long pile. At the same time, a steel pile shoe is installed at the pile tip to form the final post-tensioned prestressed large pipe pile product.

[0004] The existing methods for testing the axial force of large post-tensioned prestressed concrete pipe piles mainly include two categories. The first category is to pre-embed a concrete strain gauge to test the strain of the pile body during the process of making piles with a single pipe section, and then connect the data lines of the sensors of each pipe section to form a test system. This type of method has the following obvious defects: ① The survival rate of the sensor after high-speed rotation and high-temperature steam curing is low; ② The process of connecting multiple pipe sections in series is difficult, and the wiring parts are easily damaged during construction, and the test quality cannot be guaranteed. The second category is to paste sensors and data wires on the inner wall of the pipe concrete after the large pipe pile is formed and protect them. The obvious defects of this type of method are: ① The rotary pile-making process causes the inner wall concrete to have a lot of loose slurry, abnormal elastic modulus, and large errors in the test results; ② The exposed wires are easily damaged by soil extrusion during the pile driving process after being covered and protected, and the test quality cannot be guaranteed.

[0005] To this end, the applicant has designed and developed a post-implanted post-tensioned large pipe pile axial force testing device and testing method to solve the above-mentioned problems. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a post-implanted post-tensioned prestressed large pipe pile axial force testing device and testing method.

[0007] The present invention is implemented as follows: a post-implanted post-tensioned large pipe pile axial force testing device comprises a post-tensioned large pipe pile formed by splicing a plurality of concrete pipe piles; the characteristics are as follows: two metal pipes with a diameter smaller than the wall thickness of the concrete pipe pile are pre-installed at the center of the pipe wall of each section of the concrete pipe pile, and the two metal pipes are symmetrically distributed relative to the center of the concrete pipe pile; and the length of the two metal pipes is equal to the length of the concrete pipe pile; after the plurality of sections of the concrete pipe piles are spliced, the metal pipes of the adjacent concrete pipe piles are spliced ​​to form a through sensor installation channel, and a sensor for measuring the force of ... A Bragg fiber Bragg Bragg strain sensor for pile body axial force; the Bragg fiber Bragg strain sensor is connected to an optical fiber conductor; an optical fiber conductor guide port connected to a metal pipe is provided on the inner side of the upper concrete pipe pile; the optical fiber conductor connected to the Bragg fiber Bragg strain sensor extends from the optical fiber conductor guide port to connect to an optical fiber Bragg demodulator; a grouting agent is densely filled in the sensor installation channel, and after the grouting agent solidifies, the Bragg fiber Bragg strain sensor, the optical fiber conductor, the metal pipe and the concrete pipe pile form an integrated structure; a calibration section sensor for calculating the comprehensive elastic modulus of the cross section is pre-buried near the top of the pile.

[0008] Preferably, the above technical solution is such that 6 to 8 Bragg fiber Bragg grating strain sensors are arranged in each channel; the above Bragg fiber Bragg grating strain sensors are connected in series by armored optical fibers.

[0009] Preferably, the above technical solution is that both ends of the Bragg fiber grating strain sensor are connected to the armored optical fiber through metal clamps.

[0010] Preferably, in the above technical solution, the outer diameter of the metal pipe is not greater than 1 / 3 of the wall thickness of the concrete pipe pile.

[0011] Preferably, the distance between the optical fiber wire guide port and the pile top is 2 m.

[0012] The present invention also discloses a method for manufacturing the post-implantation type post-tensioned large pipe pile axial force testing device, which is characterized in that it comprises the following steps:

[0013] S1. Making concrete pipe sections: two metal pipes with diameters smaller than the wall thickness of the concrete pipe pile are pre-installed at the center of the concrete pipe pile wall. The two metal pipes are symmetrically distributed relative to the center of the concrete pipe pile; and the lengths of the two metal pipes are equal to the length of the concrete pipe pile;

[0014] S2. Making post-tensioned prestressed large pipe piles. First, lower the concrete pipe pile with the steel pile tip to the designated position, and then lower the other concrete pipe piles one by one, ensuring that the metal pipes in the adjacent concrete pipe piles are concentric, and at the same time ensuring that the connection surfaces of the adjacent concrete pipe piles are sealed and fitted, and then perform prestressing and anchoring;

[0015] S3, making a Bragg grating strain string, several Bragg fiber Bragg strain sensors connected by armored optical cables, forming a Bragg grating strain string, the position and length of the Bragg fiber Bragg strain sensor need to be calculated in advance, metal chucks are set at both ends of the Bragg fiber Bragg strain sensor to clamp and fix it, and the Bragg fiber Bragg strain sensors are arranged at the boundaries of the soil layer at the test pile position, and 6 to 8 are arranged in each channel;

[0016] S4, inserting an armored Bragg fiber grating strain sensor with a metal clamp into the reserved metal pipe channel, so that each strain point corresponds to the boundary position of each soil layer after the pile is driven, and leading the armored optical fiber wire out of the inner wall of the pile body in advance at the optical fiber wire guide port;

[0017] S5. Test whether the Bragg fiber Bragg strain sensor works normally. If the Bragg fiber Bragg strain sensor at each soil layer boundary position can work normally after the test, proceed to the next step; if one or more Bragg fiber Bragg strain sensors do not work normally, it is necessary to take out the armored fiber optic wire through the fiber optic wire guide port for replacement or maintenance, and then lower and test it until all Bragg fiber Bragg strain sensors can work normally;

[0018] S6. After confirming that all Bragg fiber Bragg strain sensors are in normal condition, grouting treatment is performed on the sensor installation channel through the reserved grouting holes at the pile top and pile tip to ensure that the pile body is dense and has no gaps, and the entire pile body is regarded as a synchronous deformation state.

[0019] S7. Pre-embed a calibration section sensor near the top of the pile;

[0020] S8. The numerical curve of the comprehensive elastic modulus E of the pile body is calculated by the relationship between the force and strain of the calibrated section, and the axial force of the pile body of each test section is calculated by E and strain ε; a static load test is carried out and a 1Hz fiber grating demodulator is used for test collection to obtain the strain values ​​of the pile body at different parts of the pile body under different loads;

[0021] When the test pile reaches its ultimate bearing capacity,

[0022]

[0023] Calculate the axial force values ​​of different pile sections, and thus calculate the ultimate side resistance and end resistance of the layered soil; where N i is the axial force of the pile in the ith section, in kN, E is the comprehensive elastic modulus of the pile, in MPa, and A is the cross-sectional area of ​​the pile, in m 2 , ε i is the measured strain of the pile body in the ith section, in units of με.

[0024] The advantages and technical effects of the present invention are as follows: by adopting the above-mentioned test method, the present invention avoids the negative effects of rotating piles, steam curing, multiple wiring, etc. on the sensor by pre-burying a metal hole at the center of the pile wall of the pile pipe, and inserting an armored optical fiber string sensor after the pile is made, thereby improving the survival rate and accuracy of the sensor; and the sensor is located in the exact center of the pile wall, and the quality of the concrete at the center is uniform and good, so that the strain test effect is optimal; the process of post-grouting of the hole not only protects the sensor, but also improves the installation efficiency and effect of the sensor, and improves the correctness and accuracy of the axial force test. The method is easy to promote and has good effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the present invention.

[0026] In the figure, 1. concrete pipe pile; 1-1. optical fiber wire guide port; 2. metal pipe; 3. Bragg fiber Bragg strain sensor; 4. optical fiber wire; 5. fiber Bragg demodulator; 6. grouting agent; 7. calibration section sensor; 8. steel pile tip. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] See also Figure 1A post-implanted post-tensioned large pipe pile axial force testing device comprises a post-tensioned large pipe pile formed by splicing several sections of concrete pipe piles 1; two metal pipes 2 with a diameter smaller than the wall thickness of the concrete pipe pile are pre-installed at the center of the pipe wall of each section of the concrete pipe pile, and the two metal pipes are symmetrically distributed relative to the center of the concrete pipe pile; and the length of the two metal pipes is equal to the length of the concrete pipe pile; after the several sections of the concrete pipe piles are spliced, the metal pipes of the adjacent concrete pipe piles are spliced ​​to form a through sensor installation channel, and Bragg fiber grating strain sensors 3 for testing the axial force of the pile body are arranged at each boundary of the soil layer corresponding to the test pile position in the above-mentioned sensor installation channel; The Bragg fiber Bragg strain sensor is connected to an optical fiber conductor 4; an optical fiber conductor guide port 1-1 connected to the metal pipe is provided on the inner side of the upper concrete pipe pile; the optical fiber conductor connected to the Bragg fiber Bragg strain sensor extends from the optical fiber conductor guide port to connect to the optical fiber Bragg demodulator 5, which is an existing product and is used to measure the optical frequency; the sensor installation channel is densely filled with a grouting agent 6, and after the grouting agent solidifies, the Bragg fiber Bragg strain sensor, the optical fiber conductor, the metal pipe and the concrete pipe pile form an integrated structure; a calibration section sensor 7 for measuring the comprehensive elastic modulus of the pile body is pre-buried near the top of the pile.

[0029] Preferably, the above technical solution is such that 6 to 8 Bragg fiber Bragg grating strain sensors are arranged in each channel; the above Bragg fiber Bragg grating strain sensors are connected in series by armored optical fibers.

[0030] Preferably, the above technical solution is that both ends of the Bragg fiber grating strain sensor are connected to the armored optical fiber through a metal clamp 3-1.

[0031] In the above technical solution, the outer diameter of the metal pipe is preferably not greater than 1 / 3 of the wall thickness of the concrete pipe pile. Preferably, the outer diameter of the metal pipe is 44 mm and the wall thickness is 2 mm;

[0032] Preferably, the distance between the optical fiber wire guide port and the pile top is 2 m.

[0033] The present invention also discloses a method for manufacturing the post-implantation type post-tensioned large pipe pile axial force testing device, which is characterized in that it comprises the following steps:

[0034] S1. Making concrete pipe segments: two metal pipes with diameters smaller than the wall thickness of the concrete pipe pile are pre-installed at the center of the concrete pipe pile wall, and the two metal pipes are symmetrically distributed relative to the center of the concrete pipe pile; and the lengths of the two metal pipes are equal to the length of the concrete pipe pile; each concrete pipe pile is normally rotated into a pile and steam cured, which belongs to the prior art and will not be described in detail here;

[0035] S2, making post-tensioned prestressed large pipe piles, first lowering the concrete pipe pile with the steel pile tip 8 to the specified position, and then lowering other concrete pipe piles one by one, ensuring that the metal pipes in adjacent concrete pipe piles are concentric, and at the same time ensuring that the connecting surfaces of adjacent concrete pipe piles are sealed and fitted, and then prestressing and anchoring are performed, wherein the tensioning and anchoring belong to conventional techniques in this field and will not be described in detail here;

[0036] S3, making a Bragg grating strain string, several Bragg fiber Bragg strain sensors connected by armored optical cables, forming a Bragg grating strain string, the position and length of the Bragg fiber Bragg strain sensor need to be calculated in advance, metal chucks are set at both ends of the Bragg fiber Bragg strain sensor to clamp and fix it, and the Bragg fiber Bragg strain sensors are arranged at the boundaries of the soil layer at the test pile position, and 6 to 8 are arranged in each channel;

[0037] S4, inserting an armored Bragg fiber grating strain sensor with a metal clamp into the reserved metal pipe channel, so that each strain point corresponds to the boundary position of each soil layer after the pile is driven, and leading the armored optical fiber wire out of the inner wall of the pile body in advance at the optical fiber wire guide port;

[0038] S5. Test whether the Bragg fiber Bragg strain sensor works normally. If the Bragg fiber Bragg strain sensor at each soil layer boundary position can work normally after the test, proceed to the next step; if one or more Bragg fiber Bragg strain sensors do not work normally, it is necessary to take out the armored fiber optic wire through the fiber optic wire guide port for replacement or maintenance, and then lower and test it until all Bragg fiber Bragg strain sensors can work normally;

[0039] S6. After confirming that all Bragg fiber Bragg strain sensors are in normal condition, grouting is performed on the sensor installation channels through the reserved grouting holes at the pile top and pile tip using P.O42.5 cement mixed with 3% HLC-VII grouting agent to ensure that the pile body is dense and has no gaps. The entire pile body is regarded as a synchronous deformation state;

[0040] S7. Pre-embed a calibration section sensor near the top of the pile;

[0041] S8. The numerical curve of the comprehensive elastic modulus E of the pile body is calculated by the relationship between the force and strain of the calibrated section, and the axial force of the pile body of each test section is calculated by E and strain ε; a static load test is carried out and a 1Hz fiber grating demodulator is used for test collection to obtain the strain values ​​of the pile body at different parts of the pile body under different loads;

[0042] When the test pile reaches its ultimate bearing capacity,

[0043]

[0044] Calculate the axial force values ​​of different pile sections, and thus calculate the ultimate side resistance and end resistance of the layered soil; where N i is the axial force of the pile in the ith section, in kN, E is the comprehensive elastic modulus of the pile, in MPa, and A is the cross-sectional area of ​​the pile, in m 2 , ε i is the measured strain of the pile body in the ith section, in units of με.

[0045] The advantages and technical effects of the present invention are as follows: by adopting the above-mentioned test method, the present invention avoids the negative effects of rotating piles, steam curing, multiple wiring, etc. on the sensor by pre-burying a metal hole at the center of the pile wall of the pile pipe, and inserting an armored optical fiber string sensor after the pile is made, thereby improving the survival rate and accuracy of the sensor; and the sensor is located in the exact center of the pile wall, and the quality of the concrete at the center is uniform and good, so that the strain test effect is optimal; the process of post-grouting of the hole not only protects the sensor, but also improves the installation efficiency and effect of the sensor, and improves the correctness and accuracy of the axial force test. The method is easy to promote and has good effects.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention, such as the model of the sensor, the material of the metal tube, etc., should be included in the protection scope of the present invention.

Claims

1. A post-implanted post-tensioned large pipe pile axial force testing device, comprising a post-tensioned large pipe pile formed by splicing several sections of concrete pipe piles; characterized in that: Two metal tubes with diameters smaller than the wall thickness of the concrete pile are pre-installed at the center of the wall of each section of the concrete pile, and the two metal tubes are symmetrically distributed relative to the center of the concrete pile; and the length of the two metal tubes is equal to the length of the concrete pile; after several sections of the concrete pile are spliced, the metal tubes of the adjacent concrete piles are spliced ​​to form a through sensor installation channel, and Bragg fiber grating strain sensors for measuring the axial force of the pile body are arranged at each boundary of the soil layer corresponding to the test pile position in the above sensor installation channel; the Bragg fiber grating strain sensor is connected to the optical fiber wire; an optical fiber wire guide port connected to the metal tube is arranged on the inner side of the concrete pile located at the upper part; the optical fiber wire connected to the Bragg fiber grating strain sensor is extended from the optical fiber wire guide port to connect to the optical fiber grating demodulator; the sensor installation channel is densely filled with grouting agent, and after the grouting agent solidifies, the Bragg fiber grating strain sensor, the optical fiber wire, the metal tube and the concrete pile form an integrated structure; a calibration section sensor for calculating the comprehensive elastic modulus of the cross section is pre-buried near the top of the pile.

2. The post-implanted post-tensioned large pipe pile axial force testing device according to claim 1 is characterized in that: Each channel is arranged with 6 to 8 Bragg fiber Bragg strain sensors; the Bragg fiber Bragg strain sensors are connected in series by armored optical fibers.

3. The post-implanted post-tensioned large pipe pile axial force testing device according to claim 1 is characterized in that: Both ends of the Bragg fiber grating strain sensor are connected to the armored optical fiber through metal clamps.

4. The post-implanted post-tensioned large pipe pile axial force testing device according to claim 1 is characterized in that: The outer diameter of the metal pipe shall not be greater than 1 / 3 of the wall thickness of the concrete pipe pile.

5. The post-implanted post-tensioned large pipe pile axial force testing device according to claim 1 is characterized in that: The distance between the optical fiber wire guide port and the pile top is 2m.

6. A method for manufacturing a post-implanted post-tensioned large pipe pile axial force testing device according to any one of claims 1 to 5, characterized in that: The steps include: S1. Making concrete pipe sections: two metal pipes with diameters smaller than the wall thickness of the concrete pipe pile are pre-installed at the center of the concrete pipe pile wall. The two metal pipes are symmetrically distributed relative to the center of the concrete pipe pile; and the lengths of the two metal pipes are equal to the length of the concrete pipe pile; S2. Making post-tensioned prestressed large pipe piles. First, lower the concrete pipe pile with the steel pile tip to the designated position, and then lower the other concrete pipe piles one by one, ensuring that the metal pipes in the adjacent concrete pipe piles are concentric, and at the same time ensuring that the connection surfaces of the adjacent concrete pipe piles are sealed and fitted, and then perform prestressing and anchoring; S3, making a Bragg grating strain string, several Bragg fiber Bragg strain sensors connected by armored optical cables, forming a Bragg grating strain string, the position and length of the Bragg fiber Bragg strain sensor need to be calculated in advance, metal chucks are set at both ends of the Bragg fiber Bragg strain sensor to clamp and fix it, and the Bragg fiber Bragg strain sensors are arranged at the boundaries of the soil layer at the test pile position, and 6 to 8 are arranged in each channel; S4, inserting an armored Bragg fiber grating strain sensor with a metal clamp into the reserved metal pipe channel, so that each strain point corresponds to the boundary position of each soil layer after the pile is driven, and leading the armored optical fiber wire out of the inner wall of the pile body in advance at the optical fiber wire guide port; S5. Test whether the Bragg fiber Bragg strain sensor works normally. If the Bragg fiber Bragg strain sensor at each soil layer boundary position can work normally after the test, proceed to the next step; if one or more Bragg fiber Bragg strain sensors do not work normally, it is necessary to take out the armored fiber optic wire through the fiber optic wire guide port for replacement or maintenance, and then lower and test it until all Bragg fiber Bragg strain sensors can work normally; S6. After confirming that all Bragg fiber Bragg strain sensors are in normal condition, grouting is performed on the sensor installation channel through the reserved grouting holes at the pile top and pile tip to ensure that the pile body is dense and has no gaps, and the entire pile body is regarded as a synchronous deformation state; S7. Pre-embed a calibration section sensor near the top of the pile; S8. The numerical curve of the comprehensive elastic modulus E of the pile body is calculated by the relationship between the force and strain of the calibrated section, and the axial force of the pile body of each test section is calculated by E and strain ε; a static load test is carried out and a 1Hz fiber grating demodulator is used for test collection to obtain the strain values ​​of the pile body at different parts of the pile body under different loads; When the test pile reaches its ultimate bearing capacity, Calculate the axial force values ​​of different pile sections, and thus calculate the ultimate side resistance and end resistance of the layered soil; where N i is the axial force of the pile in the i-th section, in kN, E is the comprehensive elastic modulus of the pile, in MPa, and A is the cross-sectional area of ​​the pile, in m 2 , ε i is the measured strain of the pile body in the ith section, in units of με.

Images