Testing equipment and testing method for testing connection performance between piles and columns

Abstract

The present invention discloses a detection device and a detection method for detecting the connection performance between piles and columns, wherein the detection device includes a platform system, a load loading system and a data system; the platform system includes a loading platform and a platform bracket, the loading platform is installed on the top of the platform bracket, and is placed horizontally through the platform bracket; the load loading system is installed on the top surface of the placement platform and is located between two placement through holes, the load loading system includes a hydraulic control system, a horizontal jack, a force transmission column and a spherical hinge support; the data system includes a plurality of data acquisition sensor groups and a data receiving control end, the plurality of data acquisition sensor groups are installed on the pile column to be tested, and are sequentially arranged along the height direction of the pile column to be tested, the data receiving control end is not located on the loading platform, and is respectively connected to each displacement sensor, each strain sensor and the hydraulic control system. The present invention can realize the detection and evaluation of the connection performance between the pile columns of the substructure of the assembled bridge.

Description

Technical Field

[0001] The present invention relates to the field of construction inspection of prefabricated bridges, and in particular to an inspection device and an inspection method for inspecting the connection performance between piles and columns, which is specifically aimed at the substructure of a bridge using a "pile-column integration" process. Background Art

[0002] With the guidance of national and local policies in recent years, prefabricated construction technology has been strongly developed. The prefabricated construction technology of bridges has gradually expanded from the prefabrication and assembly of the upper structure to the lower structure. Since the piles and columns in the lower structure of the bridge are often tens of meters long, in order to facilitate prefabrication and transportation, they often need to be prefabricated into multiple sections, and then transported to the site for on-site splicing. At the same time, in order to simplify on-site construction and reduce the site occupation area after construction, the traditional cap connection form between the piles and columns is changed to a welding connection or a flange connection, that is, the cap structure is removed, and the lower structure of the bridge is designed as "pile-column integration". When the bridge is subjected to upper horizontal loads (vehicles, temperature, earthquakes, etc.), it will be transmitted to the lower part through welding connections or flange connections. If the connection quality is not up to standard, it will directly affect the safety of the bridge structure. Therefore, it is crucial to ensure the connection quality between piles and columns. At present, the specification has clear requirements for the horizontal bearing capacity test of piles, but there is no clear detection method for the detection of the connection performance between piles and columns. Based on this, the present invention proposes a detection device and a detection method for detecting the connection performance between piles and columns. Summary of the invention

[0003] In view of the above, it is necessary to provide a detection device and a detection method for detecting the connection performance between piles and columns, so as to realize the detection and evaluation of the connection performance between piles and columns of the substructure of prefabricated bridges.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A detection device for detecting the connection performance between piles and columns, comprising a platform system, a load loading system and a data system; the platform system comprises a loading platform and a platform bracket, the loading platform is installed on the top of the platform bracket, and is placed horizontally through the platform bracket, two placement through holes are spaced apart on the loading platform, and two piles to be tested are penetrated through the two placement through holes, the aperture of the placement through holes is larger than the pipe diameter of the pile to be tested, and the loading platform is close to the top of the pile to be tested relative to the connection between the two piles on the pile to be tested; the load loading system is installed on the top surface of the loading platform and is located between the two placement through holes, and the load loading system comprises a hydraulic control system, a horizontal jack, a force transmission column and a spherical hinge support, the hydraulic control system is connected to the horizontal jack, the horizontal jack is placed horizontally, and its two ends in the telescopic direction are respectively connected to a pile to be tested through the force transmission column and the spherical hinge support, and the top thrust generated by the horizontal jack, the force transmission column and the spherical hinge support axis are On the same straight line, the straight line passes through the center line of the pile column to be measured; the data system includes a plurality of data acquisition sensor groups and a data receiving control end, the plurality of data acquisition sensor groups are installed on the pile column to be measured, and are arranged in sequence along the height direction of the pile column to be measured, and data acquisition sensor groups are arranged on the upper and lower sides of the connection of each pile column to be measured, each data acquisition sensor group includes two displacement sensors and two strain sensors, all sensors in each data acquisition sensor group are located at the same height of the two pile columns to be measured, and a displacement sensor and a strain sensor in a data acquisition sensor group are arranged at the same height of each pile column to be measured, the displacement sensor and the strain sensor are arranged on the opposite sides of the pile column to be measured, and are located in the plane formed by the jacking force generated by the horizontal jack and the center line of the pile column to be measured, the data receiving control end is not located on the loading platform, and is respectively connected to each displacement sensor, each strain sensor and the hydraulic control system.

[0006] Furthermore, the platform support is constructed using steel pipes.

[0007] Furthermore, the top surface of the loading platform is 1 m away from the top of the pile to be tested.

[0008] Furthermore, the vertical spacing between two adjacent data acquisition sensor groups close to the connection of the pile column to be measured is smaller than the vertical spacing between two adjacent data acquisition sensor groups far from the connection of the pile column to be measured.

[0009] In addition, the present invention also proposes a detection method for detecting the connection performance between piles and columns, which uses the above-mentioned detection device for detecting the connection performance between piles and columns. The detection method comprises the following steps:

[0010] (1) Excavate the ground around the piles to be tested so that the connection between the piles is exposed for more than 1m;

[0011] (2) Set up a loading platform and platform support 1m away from the top of the pile to be tested, and ensure that the top surface of the loading platform is level;

[0012] (3) Grind the outer surface of the pile to be tested and mark it at a certain interval;

[0013] (4) Install displacement sensors and strain sensors at the marked locations, increase the density of sensors within 1 m from the connection between the piles, and the maximum vertical spacing between two adjacent sensors within this range should not be greater than 0.5 m. Then connect each sensor to the data receiving control terminal with wires;

[0014] (5) Install the horizontal jack, force transmission column and spherical hinge support on the loading platform;

[0015] (6) The test load is graded according to the estimated ultimate bearing capacity of the pile column to be tested, and the increment of each load grade is determined. The estimated ultimate bearing capacity is the horizontal ultimate bearing capacity of the pile column to be tested;

[0016] (7) Warm up the horizontal jack for 5 minutes;

[0017] (8) The horizontal jack applies a load to the pile column to be tested by a slow load maintenance method, and collects displacement and strain data after each load level is applied and the displacement sensor detects that the displacement of the pile column to be tested is stable, and transmits the collected displacement and strain data to the data receiving control end;

[0018] (9) Uninstall;

[0019] (10) The collected data are integrated at the data receiving and controlling end, and the connection performance between the piles to be tested is evaluated based on the integrated information.

[0020] Furthermore, in step (6), the estimated ultimate bearing capacity is 1.5 times the design load, and the maximum load of each load level during the test is 1 / 10 of the estimated ultimate bearing capacity.

[0021] Furthermore, in step (8), after each level of load is applied, the horizontal displacement is measured at 5 minutes, 15 minutes, 30 minutes, 45 minutes and 60 minutes respectively, and then the horizontal displacement is measured every 30 minutes; the standard for judging the stability of the displacement of the pile column to be tested after each level of load is applied is: starting from the 30th minute after the graded load is applied, the horizontal displacement of the pile top measured every 30 minutes does not exceed 0.1 mm, and this occurs three times in succession, indicating that the horizontal displacement of the pile column to be tested is stable; when the displacement rate of the pile top reaches the above standard, the next level of load can be applied.

[0022] Furthermore, in step (8), loading can be terminated when one of the following situations occurs:

[0023] 1) The pile body is broken;

[0024] 2) When the horizontal displacement of the pile to be tested exceeds 40mm;

[0025] 3) The applied horizontal load has exceeded the limit load determined by the horizontal load-time-pile top horizontal displacement (Ht-Y0) curve or the horizontal load-displacement gradient (H-ΔY0 / ΔH) curve;

[0026] 4) The horizontal displacement of the pile to be tested reaches the allowable value of horizontal displacement required by the design.

[0027] Furthermore, in step (9), during unloading, the load is unloaded in stages at twice the load level of each loading grade. Each load level should be maintained for 1 hour. After the horizontal displacement is measured at the 15th, 30th and 60th minute respectively, the next load level can be unloaded. After unloading to zero, the residual displacement should be measured. The measurement duration shall not be less than 3 hours. The measurement time is the 15th and 30th minute, and the residual displacement is measured every 30 minutes thereafter.

[0028] Furthermore, in step (10), the connection performance evaluation method between the piles to be tested is as follows:

[0029] 1) During the process of loading to the maximum test load, if there is obvious fracture or bending at the connection between the piles and columns, the connection quality between the piles and columns to be tested can be directly assessed as unqualified;

[0030] 2) If the situation in 1) does not occur, the connection performance between the piles and columns is determined by the following method:

[0031] a) Obtain the displacement data and strain data at each mark when the horizontal displacement is stable under each load level;

[0032] b) For the data under a certain level of load, the displacement data of the two piles to be tested at the same height are averaged as the displacement value at that height, and the strain data of the two piles to be tested at the same height are averaged as the strain value at that height;

[0033] c) performing a difference in height for the displacement values ​​at different heights, thereby obtaining a differential scatter point of the displacement distribution along the pile height, or performing a difference in height for the strain values ​​at different heights, thereby obtaining a differential scatter point of the strain distribution along the pile height; wherein the differential value of the displacement or strain of each differential scatter point is calculated as follows:

[0034]

[0035] In formula (1), c i represents the differential value of displacement or strain at the i-th point, d i represents the displacement or strain value of the i-th point, h iIndicates the height of the i-th point from the ground, i = 1, 2, 3...;

[0036] d) For the difference value c i Polynomial fitting is performed to obtain a differential curve based on displacement or a differential curve based on strain, and the connection performance between piles and columns is determined according to the smoothness of the obtained differential curve.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The detection equipment for detecting the connection performance between piles and columns proposed by the present invention only needs to add a loading platform and some measuring point arrangements on the basis of the instrument used for the horizontal bearing capacity test of conventional piles. The slow sustained load method adopted by the equipment is also consistent with the conventional pile column detection loading method, which is easy for detection personnel to master.

[0039] (2) The detection method for detecting the connection performance between piles and columns proposed in the present invention can detect the connection performance between piles and columns. The detection method has the advantages of simple calculation and clear results, and is easy for detection personnel to master. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a layout diagram of the detection device of the present invention;

[0041] Figure 2 It is the differential curve diagram when the connection between the piles to be tested is intact;

[0042] Figure 3 It is a differential curve diagram when there is a defect in the connection between the piles to be tested.

[0043] Main component symbols

[0044] In the figure: loading platform 1, platform bracket 2, horizontal jack 3, force transmission column 4, spherical hinge support 5, displacement sensor 6, strain sensor 7, data receiving control terminal 8, pile column to be tested 9, welding connection 10, flange connection 11.

[0045] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0046] See also Figure 1 In a preferred embodiment of the present invention, a detection device for detecting the connection performance between piles and columns includes a platform system, a load loading system and a data system.

[0047] The platform system includes a loading platform 1 and a platform bracket 2. The loading platform 1 is installed on the top of the platform bracket 2 and is placed horizontally by the platform bracket 2. Two placement through holes are spaced apart on the loading platform 1, and two piles 9 to be tested are penetrated through the two placement through holes. The aperture of the placement through holes is larger than the diameter of the pile 9 to be tested, so that there is enough space between the loading platform 1 and the pile, so that the pile can be deformed sufficiently after loading. The connection between the two piles on the loading platform relative to the pile 9 to be tested is close to the top of the pile 9 to be tested, and specifically, the top surface of the loading platform 1 is 1m away from the top of the pile 9 to be tested. In this embodiment, the platform bracket 2 is constructed by steel pipes.

[0048] The load loading system is installed on the top surface of the loading platform and is located between the two placement through holes. The load loading system includes a hydraulic control system, a horizontal jack 3, a force transmission column 4 and a spherical hinge support 5. The hydraulic control system is connected to the horizontal jack 3 to control the jacking force of the horizontal jack 3 through the hydraulic control system. The horizontal jack 3 is placed horizontally, and its two ends in the telescopic direction are respectively connected to a pile column 9 to be tested through the force transmission column 4 and the spherical hinge support 5 to transmit the jacking force to the pile column 9 to be tested. The jacking force generated by the horizontal jack 3, the force transmission column 4 and the spherical hinge support 5 are in the same straight line, and the straight line passes through the center line of the pile column 9 to be tested. In this embodiment, the measuring range of the horizontal jack 3 should be greater than the total horizontal allowable deformation of the pile column.

[0049] The data system includes a plurality of data acquisition sensor groups and a data receiving control terminal 8. The plurality of data acquisition sensor groups are installed on the pile columns 9 to be tested and are arranged in sequence along the height direction of the pile columns 9 to be tested. The data acquisition sensor groups are arranged on both sides of the upper and lower sides of the connection of each pile column 9 to be tested. Each data acquisition sensor group includes two displacement sensors 6 and two strain sensors 7. All sensors in each data acquisition sensor group are located at the same height of the two pile columns 9 to be tested. A displacement sensor 6 and a strain sensor 7 in a data acquisition sensor group are arranged at the same height of each pile column 9 to be tested. , the displacement sensor 6 and the strain sensor 7 are arranged on opposite sides of the pile column 9 to be tested, and are located in the plane formed by the thrust force generated by the horizontal jack 3 and the center line of the pile column 9 to be tested. The data receiving control terminal 8 is not located on the loading platform 1, and is respectively connected to each displacement sensor 6, each strain sensor 7 and the hydraulic control system. The displacement sensor 6 is used to detect the displacement change in the horizontal direction when the pile column 9 to be tested is subjected to the thrust of the horizontal jack 3, and the strain sensor 7 is used to detect the strain generated when the pile column 9 to be tested is subjected to the thrust of the horizontal jack 3. Furthermore, the vertical spacing between two adjacent data acquisition sensor groups close to the connection of the pile column 9 to be tested is smaller than the vertical spacing between two adjacent data acquisition sensor groups far from the connection of the pile column 9 to be tested, so as to accurately know the displacement change and strain of the connection.

[0050] In addition, based on the above detection device for detecting the connection performance between piles and columns, the present invention also proposes a detection method for detecting the connection performance between piles and columns, and the detection method comprises the following steps:

[0051] (1) Excavate the ground around the pile column 9 to be tested so that the connection between the pile columns (the connection is actually welded 10 or flanged 11) is exposed for more than 1m.

[0052] (2) A loading platform 1 and a platform support 2 are set up 1 m away from the top of the pile column 9 to be tested, and the top surface of the loading platform 1 is ensured to be level.

[0053] (3) The outer surface of the pile column 9 to be tested is polished and marked at a certain interval.

[0054] (4) Install displacement sensors 6 and strain sensors 7 at the marked locations, increase the density of sensors within 1 m from the connection between the piles, and the maximum vertical spacing between two adjacent sensors within this range should not be greater than 0.5 m. Then connect each sensor to the data receiving control terminal 8 with wires.

[0055] (5) Install the horizontal jack 3, force transmission column 4 and spherical hinge support 5 on the loading platform 1.

[0056] (6) The test load is graded according to the estimated ultimate bearing capacity of the pile column to be tested, and the increment of each load level is determined. The estimated ultimate bearing capacity is the horizontal ultimate bearing capacity of the pile column to be tested (also the maximum horizontal thrust value of the pile column to be tested). In the present invention, the estimated ultimate bearing capacity is 1.5 times the design load, and the maximum load of each load level during the test is 1 / 10 of the estimated ultimate bearing capacity.

[0057] (7) Warm up the horizontal jack 3 for 5 minutes.

[0058] (8) The horizontal jack 3 applies load to the pile column 9 to be tested by a slow-maintained load method, and collects displacement and strain data after each level of load is applied and the displacement sensor 6 detects that the displacement of the pile column 9 to be tested is stable. The collected displacement and strain data are transmitted to the data receiving control terminal 8. In the present invention, the collection of displacement and strain data is carried out by applying load step by step. When collecting displacement and strain data, after each level of load is applied, the horizontal displacement is measured at 5 minutes, 15 minutes, 30 minutes, 45 minutes, and 60 minutes, and then the horizontal displacement is measured every 30 minutes; the standard for judging the displacement stability of the pile column 9 to be tested after each level of load is applied is: starting from the 30th minute after the graded load is applied, the horizontal displacement of the pile top measured every 30 minutes does not exceed 0.1 mm, and this occurs three times in a row, which means that the horizontal displacement of the pile column 9 to be tested is stable; when the displacement rate of the pile top reaches the above standard, the next level of load can be applied.

[0059] It should be noted that during the loading process, if one of the following situations occurs, the loading can be terminated:

[0060] 1) The pile body is broken;

[0061] 2) When the horizontal displacement of the pile column 9 to be tested exceeds 40 mm;

[0062] 3) The applied horizontal load has exceeded the limit load determined by the horizontal load-time-pile top horizontal displacement (Ht-Y0) curve or the horizontal load-displacement gradient (H-ΔY0 / ΔH) curve;

[0063] 4) The horizontal displacement of the pile column 9 to be tested reaches the allowable value of horizontal displacement required by the design.

[0064] (9) Unloading: Specifically, during unloading, the load should be twice the load level of each loading level. Each load level should be maintained for 1 hour. After the horizontal displacement is measured at the 15th, 30th and 60th minute, the next load level can be unloaded. After unloading to zero, the residual displacement should be measured. The measurement duration should not be less than 3 hours. The measurement time is the 15th and 30th minute. The residual displacement should be measured every 30 minutes thereafter.

[0065] (10) The collected data is integrated at the data receiving control terminal 8, and the connection performance between the piles 9 to be tested is evaluated based on the integrated information; specifically, the connection performance evaluation method between the piles 9 to be tested is as follows:

[0066] 1) During the process of loading to the maximum test load, if there is obvious fracture, bending, etc. at the connection between the piles, it can be directly assessed that the connection quality between the piles to be tested 9 is unqualified;

[0067] 2) If the situation in 1) does not occur, the connection performance between the piles and columns is determined by the following method:

[0068] a) Obtain the displacement data and strain data at each mark when the horizontal displacement is stable under each load level;

[0069] b) For the data under a certain level of load, the displacement data on the two piles 9 to be tested at the same height are averaged as the displacement value at the height, and the strain data on the two piles 9 to be tested at the same height are averaged as the strain value at the height;

[0070] c) performing a difference in height for the displacement values ​​at different heights, thereby obtaining a differential scatter point of the displacement distribution along the pile height, or performing a difference in height for the strain values ​​at different heights, thereby obtaining a differential scatter point of the strain distribution along the pile height; wherein the differential value of the displacement or strain of each differential scatter point is calculated as follows:

[0071]

[0072] In formula (1), c i represents the differential value of displacement or strain at the i-th point, d i represents the displacement or strain value of the i-th point, h i Indicates the height of the i-th point from the ground, i = 1, 2, 3...;

[0073] d) For the difference value c i Perform polynomial fitting to obtain a displacement-based differential curve or a strain-based differential curve. The connection performance between piles and columns is determined based on the smoothness of the obtained differential curve. For example, Figure 2 and Figure 3 The difference curve diagram shown in Figure 2 It is the differential curve diagram when the 9 connections between the piles to be tested are intact. Figure 3 is the differential curve when there are defects at the 9 connections between the tested piles. Figure 2 and Figure 3 It can be seen that Figure 2 The difference curve is smooth and has no kinks. Figure 3 The difference curve of has a kink at the first difference divergence point below the connection, which also shows Figure 3The connection of the pile column 9 to be tested is defective.

[0074] In summary, the detection method provided by the present invention can detect the connection performance between piles and columns, and the detection method is simple, easy to operate and has good practicality.

[0075] The above description is a detailed description of the preferred feasible embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modified changes completed under the technical spirit suggested by the present invention should fall within the patent scope covered by the present invention.

Claims

1. A detection device for detecting the connection performance between piles and columns, characterized in that: The invention comprises a platform system, a load loading system and a data system; the platform system comprises a loading platform and a platform bracket, the loading platform is installed on the top of the platform bracket, and is placed horizontally through the platform bracket, two placement through holes are arranged on the loading platform at intervals, and two piles to be tested are penetrated through the two placement through holes, the aperture of the placement through holes is larger than the pipe diameter of the pile to be tested, the loading platform is close to the top of the pile to be tested relative to the connection between the two piles on the pile to be tested, and the connection between the two piles on the pile to be tested is welded or flanged; the load loading system is installed on the top surface of the loading platform and is located between the two placement through holes, the load loading system comprises a hydraulic control system, a horizontal jack, a force transmission column and a spherical hinge support, the hydraulic control system is connected to the horizontal jack, the horizontal jack is placed horizontally, and its two ends in the telescopic direction are respectively connected to a pile to be tested through the force transmission column and the spherical hinge support, the top thrust generated by the horizontal jack, the force transmission column and the spherical hinge support The axis of the seat is in the same straight line, and the straight line passes through the center line of the pile column to be measured; the data system includes a plurality of data acquisition sensor groups and a data receiving control end, the plurality of data acquisition sensor groups are installed on the pile column to be measured, and are arranged in sequence along the height direction of the pile column to be measured, and data acquisition sensor groups are arranged on both sides of the upper and lower sides of the connection of each pile column to be measured, each data acquisition sensor group includes two displacement sensors and two strain sensors, all sensors in each data acquisition sensor group are located at the same height of the two pile columns to be measured, and a displacement sensor and a strain sensor in a data acquisition sensor group are arranged at the same height of each pile column to be measured, the displacement sensor and the strain sensor are arranged on opposite sides of the pile column to be measured, and are located in a plane formed by the top thrust generated by the horizontal jack and the center line of the pile column to be measured, the data receiving control end is not located on the loading platform, and is respectively connected to each displacement sensor, each strain sensor and the hydraulic control system; The vertical spacing between two adjacent data acquisition sensor groups close to the connection of the pile column to be measured is smaller than the vertical spacing between two adjacent data acquisition sensor groups far from the connection of the pile column to be measured.

2. The detection device for detecting the connection performance between piles and columns according to claim 1, characterized in that: The platform support is constructed using steel pipes.

3. The detection device for detecting the connection performance between piles and columns according to claim 1, characterized in that: The top surface of the loading platform is 1m away from the top of the pile to be tested.

4. A method for detecting the connection performance between piles and columns, which uses the detection device for detecting the connection performance between piles and columns as claimed in claim 1, characterized in that: The detection method comprises the following steps: (1) Excavate the ground around the piles to be tested so that the connection between the piles is exposed for more than 1m; (2) Set up a loading platform and platform support 1m away from the top of the pile to be tested, and ensure that the top surface of the loading platform is level; (3) Grind the outer surface of the pile to be tested and mark it at a certain interval; (4) Install displacement sensors and strain sensors at the marked locations, increase the density of sensors within 1 m from the connection between the piles, and the maximum vertical spacing between two adjacent sensors within this range should not be greater than 0.5 m. Then connect each sensor to the data receiving control terminal with wires; (5) Install the horizontal jack, force transmission column and spherical hinge support on the loading platform; (6) The test load is graded according to the estimated ultimate bearing capacity of the pile column to be tested, and the increment of each load grade is determined. The estimated ultimate bearing capacity is the horizontal ultimate bearing capacity of the pile column to be tested; (7) Warm up the horizontal jack for 5 minutes; (8) The horizontal jack applies a load to the pile column to be tested by a slow load maintenance method, and collects displacement and strain data after each load level is applied and the displacement sensor detects that the displacement of the pile column to be tested is stable, and transmits the collected displacement and strain data to the data receiving control end; (9) Uninstall; (10) The collected data are integrated at the data receiving and controlling end, and the connection performance between the piles to be tested is evaluated based on the integrated information.

5. A detection method for detecting the connection performance between piles and columns as claimed in claim 4, characterized in that: In step (6), the estimated ultimate bearing capacity is 1.5 times the design load, and the maximum load for each load level during the test is 1 / 10 of the estimated ultimate bearing capacity.

6. A detection method for detecting the connection performance between piles and columns as claimed in claim 4, characterized in that: In step (8), after each level of load is applied, the horizontal displacement is measured at 5 minutes, 15 minutes, 30 minutes, 45 minutes and 60 minutes respectively, and then the horizontal displacement is measured every 30 minutes; the standard for judging the stability of the displacement of the pile column to be tested after each level of load is applied is: starting from the 30th minute after the graded load is applied, the horizontal displacement of the pile top measured every 30 minutes does not exceed 0.1 mm, and this occurs three times in succession, then the horizontal displacement of the pile column to be tested is judged to be stable; when the displacement rate of the pile top reaches the above standard, the next level of load can be applied.

7. A detection method for detecting the connection performance between piles and columns as claimed in claim 4, characterized in that: In step (8), loading can be terminated when one of the following situations occurs: 1) The pile body is broken; 2) When the horizontal displacement of the pile to be tested exceeds 40mm; 3) The applied horizontal load has exceeded the limit load determined by the horizontal load-time-pile top horizontal displacement (Ht-Y0) curve or the horizontal load-displacement gradient (H-ΔY0 / ΔH) curve; 4) The horizontal displacement of the pile to be tested reaches the allowable value of horizontal displacement required by the design.

8. A detection method for detecting the connection performance between piles and columns as claimed in claim 5, characterized in that: In step (9), during unloading, the load is unloaded in stages at twice the load level of each loading grade. Each load level should be maintained for 1 hour. After the horizontal displacement is measured at the 15th, 30th and 60th minute respectively, the next load level can be unloaded. After unloading to zero, the residual displacement should be measured. The measurement duration shall not be less than 3 hours. The measurement time is the 15th and 30th minute. The residual displacement is measured every 30 minutes thereafter.

9. A detection method for detecting the connection performance between piles and columns as claimed in claim 4, characterized in that: In step (10), the connection performance evaluation method between the piles to be tested is as follows: 1) During the process of loading to the maximum test load, if there is obvious fracture or bending at the connection between the piles and columns, it can be directly assessed that the connection quality between the piles and columns to be tested is unqualified; 2) If the situation in 1) does not occur, the connection performance between the piles and columns is determined by the following method: a) Obtain the displacement data and strain data at each mark when the horizontal displacement is stable under each load level; b) For the data under a certain level of load, the displacement data of the two piles to be tested at the same height are averaged as the displacement value at that height, and the strain data of the two piles to be tested at the same height are averaged as the strain value at that height; c) performing a difference in height for the displacement values ​​at different heights, thereby obtaining a differential scatter point of the displacement distribution along the pile height, or performing a difference in height for the strain values ​​at different heights, thereby obtaining a differential scatter point of the strain distribution along the pile height; wherein the differential value of the displacement or strain of each differential scatter point is calculated as follows: In formula (1), c i represents the differential value of displacement or strain at the i-th point, d i represents the displacement or strain value of the i-th point, h i Indicates the height of the i-th point from the ground, i = 1, 2, 3...; d) For the difference value c i Polynomial fitting is performed to obtain a differential curve based on displacement or a differential curve based on strain, and the connection performance between piles and columns is determined according to the smoothness of the obtained differential curve.

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