A three-dimensional photoelastic testing device and testing method for pipe joints

Abstract

The present invention provides a three-dimensional photoelastic testing device and testing method for pipe sections, which relates to the field of pipe section model tests and includes: a transparent model box for inserting two mutually abutting pipe sections with variable included angles between the axes of the two pipe sections; a loading assembly for applying a force to the pipe sections; a photo-inspection assembly for respectively obtaining the interference fringes of the two pipe sections, the photo-inspection assembly including an outer module, an inner module and a light source, the light source being arranged on one side of the outer module away from the pipe section, the outer module including an outer polarizer and an outer quarter-wave plate, the outer module being semi-cylindrical, the axis of the outer module being parallel to the corresponding pipe section, the inner module including a photosensitive screen, an inner analyzer, an inner quarter-wave plate, an eyepiece and an objective lens, the photosensitive screen, the inner analyzer and the inner quarter-wave plate all being semi-cylindrical; a recording system for obtaining the interference fringes and the magnitude of the loading force. The present application uses a three-dimensional curved photoelastic imaging method to obtain the interference fringes of the pipe section, thereby realizing the analysis of the stress field of the pipe section.

Description

Technical Field

[0001] The present invention relates to the field of pipe joint model tests, and particularly to a three-dimensional photoelastic testing device and testing method for pipe joints. Background Art

[0002] In recent years, with the acceleration of the process of underground space development and utilization, the pipe jacking method, as a key trenchless technology, has been widely applied. For pipe jacking projects under complex engineering geological conditions, the existing relevant theories are difficult to accurately predict the interaction law between stress and deformation, and simple on-site tests often have uncertainty and randomness and are difficult to repeat. Therefore, it is necessary to design indoor model tests to accurately grasp the stress change law during pipe jacking and provide reference and guidance for actual construction.

[0003] In existing pipe jacking model test devices, the stress states mostly exist in three-dimensional forms, and theoretical calculation and analysis are often complicated, especially some stress concentration problems in components cannot be effectively analyzed. Therefore, the stress analysis of engineering components mostly uses photoelastic experimental methods for analysis. The commonly used photoelastic test method usually tests two-dimensional structures. For three-dimensional photoelastic tests and their measurements, the stress freezing method is often used. The stress freezing method is to apply a load to the test piece, heat it to the freezing temperature of the test piece material in the state where the applied load on the test piece remains unchanged, slowly cool it to room temperature, remove the external load, slice the test piece, and analyze the stress distribution by observing the interference fringes preserved on the slices. However, this method cannot completely obtain the stress distribution of the test piece, and the workload of multiple slicing is large, which does not meet the experimental conditions of multiple working conditions. Currently, there are few three-dimensional curved surface photoelastic direct imaging devices, especially for large model imaging devices. Therefore, a three-dimensional photoelastic testing device and test method for pipe joints are proposed. Summary of the Invention

[0004] The present invention provides a three-dimensional photoelastic testing device and testing method for pipe joints, and the purpose is to provide a device for photoelastic imaging based on a three-dimensional curved surface, simplifying the process and difficulty of stress field distribution research.

[0005] To achieve the above purpose, an embodiment of the present invention provides a three-dimensional photoelastic testing device for pipe joints, including:

[0006] A transparent model box, in which two pipe joints that abut against each other end to end are inserted, and the included angle between the axes of the two pipe joints is variable;

[0007] A loading assembly, which acts on one end of any pipe joint to apply a force;

[0008] Two optical detection components, respectively used to obtain the interference fringes of two pipe sections. The optical detection component includes an outer module, an inner module and a light source. The outer module is used to be arranged outside the two pipe sections. The inner module is used to be arranged inside the two pipe sections. The light source is arranged on one side of the outer module away from the outside of the pipe section. The outer module includes an outer polarizer and an outer quarter-wave plate from outside to inside. The outer module is semi-cylindrical. The axis of the outer module is parallel to the corresponding pipe section. The inner module successively includes a photosensitive screen, an inner analyzer, an inner quarter-wave plate, an eyepiece and an objective lens from outside to inside. The photosensitive screen, the inner analyzer and the inner quarter-wave plate are all semi-cylindrical;

[0009] A recording system, used to obtain the interference fringes obtained by the photosensitive screen and the magnitude of the acting force applied by the loading component.

[0010] Preferably, a pipe-passing hole is arranged on the side wall of the model box. The diameter of the pipe-passing hole is larger than the diameter of the pipe section. The pipe sections respectively penetrate through the pipe-passing holes and abut inside the model box.

[0011] Preferably, the loading component further includes a reaction frame and a jack. The jack is arranged on the reaction frame. The jack is arranged at one end of the pipe section exposed outside the model box and acts on the end of the pipe section. A pressure sensor is arranged between the jack and the abutting pipe section.

[0012] Preferably, the recording system includes a PC terminal and a digital display instrument. The digital display instrument is used to obtain the magnitude of the loading force of the pressure sensor. The digital display instrument and the photosensitive screen are respectively connected to the PC terminal in signal.

[0013] Preferably, both the pipe section and the model box are made of transparent materials.

[0014] This application also provides a three-dimensional photoelastic test method for pipe sections, using the aforementioned three-dimensional photoelastic test device for pipe sections, including:

[0015] S10. Fix the two inner modules in the two pipe sections respectively;

[0016] S20. Insert the two pipe sections into the model box from one end of the model box respectively and abut them. The two pipe sections form an axial intersection angle. Fill the model box with transparent soil at a preset temperature. The transparent soil applies different preset loads to the two pipe sections;

[0017] S30. Fix the two outer modules and the light source outside the model box respectively, and ensure that the bending directions of the inner module and the outer module of the same pipe section are opposite;

[0018] S40. Turn on the loading component, apply a loading force to the end of the pipe section exposed outside the model box, and obtain the interference fringes on the photosensitive screen for the first time;

[0019] S50. Rotate the inner module and the outer module 180° inside and outside their respective pipe sections, apply the same loading force to the same pipe section in S40, and obtain the interference fringes on the photosensitive screen for the second time;

[0020] S60. splice the interference fringes obtained twice to obtain complete interference fringes, and analyze the stress field distribution of the pipe section based on the complete interference fringes, loading force, load, and temperature.

[0021] Preferably, the three-dimensional photoelastic test method for the pipe section further includes step S70. In step S70, at least one of the following is changed: the size of the axis intersection angle, the size of the load, the size of the loading force, and the temperature of the transparent soil, and steps S10-S60 are repeated.

[0022] Preferably, the angle range of the axis intersection angle is 0-10°.

[0023] Preferably, transparent soil is filled into the model box, and the transparent soil is buried to different depths of the pipe section to form different loads.

[0024] The above solution of the present invention has the following beneficial effects:

[0025] This application uses three-dimensional curved photoelastic imaging to obtain the interference fringes of the pipe section, and then realizes the analysis of the stress field of the pipe section. This application can completely obtain the stress distribution information of the pipe section, and the operation process is more convenient and concise in the process of obtaining the stress distribution information.

[0026] The optical detection component solves the problems of low accuracy and poor adaptability in the test of cylindrical pipe sections through the curved surface adaptation optical path design and the double-wave plate closed-loop polarization control.

[0027] Other features and advantages of the present invention will be described in detail in the subsequent specific implementation part. Description of the Drawings

[0028] Figure 1 is the overall schematic diagram of this application;

[0029] Figure 2 is the schematic diagram of the axis intersection angle of the first pipe section and the second pipe section;

[0030] Figure 3 is the schematic diagram of the optical detection component;

[0031] Figure 4 is the schematic diagram of the loading component;

[0032] Figure 5 is the flow chart of the test method.

[0033]

Description of the Reference Numerals

[0034] 100 - Model box, 200 - First pipe section, 300 - Second pipe section,

[0035] 400 - Loading component, 410 - Reaction frame, 420 - Jack, 421 - Pressure sensor,

[0036] 510 - Outer module, 511 - Outer polarizer, 512 - Outer quarter - wave plate,

[0037] 520 - Inner module, 521 - Photosensitive screen, 522 - Inner quarter - wave plate, 523 - Eyepiece, 524 - Objective lens, 525 - Inner analyzer

[0038] 530 - Light source,

[0039] 600 - Recording system, 610 - PC terminal, 620 - Digital display.

[0040] α - Axis intersection angle. Detailed implementation manners

[0041] To make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments.

[0042] As Figures 1-4 shown, an embodiment of the present invention provides a three - dimensional photo - elastic test device for pipe sections, including a model box 100, a photo - inspection component, a loading component 400 and a recording system 600. The model box 100 is used for passing through two pipe sections and filling soil. The pipe sections include a first pipe section 200 and a second pipe section 300. The first pipe section 200 and the second pipe section 300 respectively penetrate into the model box 100 from the side of the model box 100 and abut against each other in the model box 100. The axis intersection angle α of the first pipe section 200 and the second pipe section 300 is variable. When passing through the first pipe section 200 and the second pipe section 300, the second pipe section 300 can be completely inside the model box 100 or partially inside the model box 100. One end of the first pipe section 200 is inside the model box 100 and the other end is outside the model box 100.

[0043] Preferably, the diameters of the first pipe section 200 and the second pipe section 300 are the same.

[0044] The optical inspection component includes a light source 530 for emitting light, an outer module 510 for being arranged outside the pipe section, and an inner module 520 for being arranged inside the pipe section. The outer module 510 includes an outer polarizer 511 and an outer quarter-wave plate 512 that are successively attached from outside to inside. In this application, the center of the pipe section is defined as the inner side, and the direction extending outward from the center of the circle is the outer side. Both the outer polarizer 511 and the outer quarter-wave plate 512 are semi-cylindrical, and the diameters of both the outer polarizer 511 and the outer quarter-wave plate 512 are larger than the diameter of the pipe section. The axial direction of the outer module 510 is parallel to the axial directions of the first pipe section 200 and the second pipe section 300. The inner module 520 includes, from outside to inside, a photosensitive screen 521, an inner analyzer 525, an inner quarter-wave plate 522, an eyepiece 523, and an objective lens 524 that are successively attached. Among them, the photosensitive screen 521, the inner analyzer 525, and the inner quarter-wave plate 522 are all semi-cylindrical, and the eyepiece 523 and the objective lens 524 are plate-shaped. The light source 530 is arranged on the outer side of the outer module 510, that is, on the side of the outer module 510 away from the pipe section.

[0045] In this application, the light rays emitted by the light source 530 pass through the outer polarizer 511, the outer quarter-wave plate 512, the pipe section, the objective lens 524, the eyepiece 523, the inner quarter-wave plate 522, and the inner analyzer 525 in sequence and are received by the photosensitive screen 521. During the process of light penetration, plane-polarized light is generated under the action of the outer polarizer 511, and the plane-polarized light is converted into circularly polarized light by the outer quarter-wave plate 512. The pipe section is a force model during the jacking process. The circularly polarized light is received by the objective lens 524 after passing through the pipe section and forms a real image. The eyepiece 523 magnifies the real image. The inner quarter-wave plate 522 restores the circularly polarized light of the real image to plane-polarized light. Interference fringes are generated after the plane-polarized light passes through the inner analyzer 525, and the interference fringes are received by the photosensitive screen 521 to achieve three-dimensional curved surface imaging. At the same time, the settings of the eyepiece 523 and the objective lens 524 ensure that the light rays passing through the pipe section are reduced by an equal multiple, ensuring that the photosensitive screen 521 can obtain the complete stress field of the pipe section.

[0046] The outer quarter-wave plate 512 is located outside the pipe section. After receiving the plane-polarized light generated by the outer polarizer 511, it converts it into circularly polarized light. This conversion can ensure that the circularly polarized light generates a birefringence effect when passing through the pipe section, forming an optical path difference related to the stress distribution. The outer quarter-wave plate 512 is semi-cylindrical and has a diameter larger than that of the pipe section, solving the problem of optical path matching of the pipe section's curved surface and avoiding phase errors caused by the deviation of the incident angle of marginal light rays. The outer quarter-wave plate 512 and the inner quarter-wave plate 522 form a closed-loop optical path, which can suppress the interference of ambient light and improve the contrast of interference fringes.

[0047] The collaborative magnification of the eyepiece 523 and the objective lens 524 enables the photosensitive screen 521 to completely receive the stress fringes of the pipe section and improves the spatial resolution.

[0048] The loading component 400 is provided at one end of the pipe segment and applies a loading force to simulate the jacking of the pipe segment.

[0049] The recording system 600 is used to obtain the interference fringes acquired by the photosensitive screen 521 and the magnitude of the loading force applied by the loading component 400.

[0050] Preferably, in the present application, the external polarizer 511 is formed by bonding multiple small pieces of polarizers into a semi-cylindrical shape, and the external quarter-wave plate 512 is formed by bonding multiple small pieces of quarter-wave plates into a semi-cylindrical shape. Similarly, the internal analyzer 525 and the internal quarter-wave plate 522 are formed by bonding the corresponding analyzers and quarter-wave plates.

[0051] The aforementioned pipe segment is made of a transparent material. In this embodiment, it is made of an epoxy resin material. The light source 530 contains white and yellow monochromatic lights, which is convenient for switching the light color to form clearer interference fringes.

[0052] Furthermore, in the present application, the side wall of the model box 100 is detachable. A pipe-passing hole is provided on one side wall of the model box 100, and the diameter of the pipe-passing hole is larger than the diameter of the pipe segment, so that the included angle between the axes of the first pipe segment 200 and the second pipe segment 300 can change.

[0053] The aforementioned loading component 400 includes a reaction frame 410. A jack 420 is provided on the reaction frame 410. The jack 420 has a telescopic end, and different loading forces are applied to the end of the pipe segment exposed outside the model box 100 by the telescopic movement of the telescopic end to simulate jacking. A pressure sensor 421 is also provided at the telescopic end of the jack 420. The pressure sensor 421 is located between the telescopic end of the jack 420 and the end of the pipe segment to obtain the loading force of the jack 420.

[0054] The recording system 600 includes a PC terminal 610 and a digital display 620. The digital display 620 is signal-connected to the pressure sensor 421 and transmits the recorded loading force information to the PC terminal 610. The PC terminal 610 is also signal-connected to the photosensitive screen 521.

[0055] Refer to Figure 5 , the present application also provides a three-dimensional photoelastic testing method for pipe segments, based on the aforementioned three-dimensional photoelastic testing device for pipe segments, which is used to simulate the change of the stress field during the jacking process of the pipe segments, including the following steps:

[0056] S10. Fix the two inner modules 520 in the first pipe segment 200 and the second pipe segment 300 respectively.

[0057] In this step, two inner modules 520 are fixed inside the first pipe section 200 and the second pipe section 300 by using a detachable fixture. The perimeter of the inner module 520 is half of the perimeter of the pipe section.

[0058] S20. Insert the first pipe section 200 and the second pipe section 300 into the model box 100 from one side of the model box 100 respectively and abut them. The first pipe section 200 and the second pipe section 300 form an axis intersection angle. Fill the model box 100 with transparent soil at a preset temperature. The transparent soil exerts different preset loads on the first pipe section 200 and the second pipe section 300.

[0059] In this step, the first pipe section 200 and the second pipe section 300 with the inner module 520 are inserted into the model box 100 respectively and abut them. The first pipe section 200 and the second pipe section 300 form different axis intersection angles according to the test requirements.

[0060] Preferably, the range of the axis intersection angle is 0 - 10°.

[0061] Heat the transparent soil to a temperature higher than the preset temperature, fill the heated transparent soil into the model box 100, and keep the axis intersection angle unchanged. The transparent soil is buried to different depths of the first pipe section 200 and the second pipe section 300, so as to exert different preset loads on the first pipe section 200 and the second pipe section 300.

[0062] Preferably, during the soil filling process, the transparent soil can be buried to all, one - half, one - third, one - fourth, etc. of the pipe section height, so as to simulate different preset loads such as full load, one - half load, etc.

[0063] S30. Fix the two outer modules 510 and the light source 530 outside the model box 100 respectively, and ensure that the bending directions of the inner module 520 and the outer module 510 in the same pipe section are opposite.

[0064] In this step, two outer modules 510 are erected outside the model box 100. Each outer module 510 is installed corresponding to the inner module 520 in the pipe section. The two light sources 530 are respectively arranged on the outer sides of the two outer modules 510, that is, on the side away from the model box 100. The light rays emitted by each light source 530 can pass through the outer module 510, the pipe section and the inner module 520 in sequence, and are received by the photosensitive screen 521 of the inner module 520.

[0065] The bending direction of the inner module 520 is to the right, and the bending direction of the outer module 510 is to the left, forming a spatial pattern where the bending directions of the inner module 520 and the outer module 510 are opposite.

[0066] S40. Turn on the loading component 400, apply a loading force to one of the pipe sections, and first obtain the interference fringes on the photosensitive screen 521.

[0067] In this step, when the temperature of the transparent soil drops to the preset temperature, a loading force is applied to one end of the first pipe section 200 that is not located inside the model box 100, and the interference fringes captured by the photosensitive screen 521 are obtained for the first time. In this embodiment, the interference fringes obtained by the photosensitive screen 521 for the first time reflect the stress field changes on the right side of the first pipe section 200 and the second pipe section 300.

[0068] S50. Rotate the inner module 520 and the outer module 510 180 degrees inside and outside their respective pipe sections, apply the same loading force to the same pipe section, and obtain the interference fringes on the photosensitive screen 521 for the second time.

[0069] In this step, the inner module 520 is rotated 180°, so that the bending direction of the inner module 520 is to the left, and the outer module 510 and the light source 530 are arranged on the other side of the first pipe section 200 and the second pipe section 300, forming a spatial pattern where the bending direction of the inner module 520 is to the left and the bending direction of the outer module 510 is to the right. After applying the same loading force to the same pipe section in step S50, the interference fringes obtained by the photosensitive screen 521 reflect the stress field changes on the left side of the first pipe section 200 and the second pipe section 300.

[0070] S60. Splice the interference fringes obtained twice to obtain complete interference fringes, and analyze the stress field distribution of each pipe section based on the complete interference fringes, the loading force, the load, and the temperature.

[0071] In step S40 and step S50, the interference fringes on one side of each of the first pipe section 200 and the second pipe section 300 are obtained respectively. The interference fringes of the first pipe section 200 and the second pipe section 300 are spliced to obtain the complete interference fringes of the first pipe section 200 and the second pipe section 300, and the stress field changes of the first pipe section 200 and the second pipe section 300 are analyzed based on the complete interference fringes, the loading force of the loading component 400, the load of the transparent soil, and the temperature.

[0072] S70. Change at least one of the axis intersection angle, the magnitude of the loading force, the load of the transparent soil, and the temperature, and repeat steps S10 - S60 to obtain the corresponding relationships between multiple groups of interference fringes and different factors, and analyze the corresponding relationships between the stress field distributions of the first pipe section 200 and the second pipe section 300 and different factors.

[0073] The corresponding relationships between the stress field distributions and different factors can be trained using existing data models. For example, using the physical neural network algorithm, a physical - data dual - driven stress PINN prediction model is established to obtain the stress field distributions of the pipe sections under different factors.

[0074] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A three-dimensional photoelastic testing method for pipe segments, using a three-dimensional photoelastic testing device for pipe segments, and the three-dimensional photoelastic testing device for pipe segments includes: A transparent model box, in which two pipe segments abutting against each other end to end are inserted, and the included angle between the axes of the two pipe segments is variable; A loading component, which acts on one end of any pipe segment to apply a force; Two photo-detection components, which are respectively used to obtain the interference fringes of the two pipe segments. The photo-detection component includes an outer module, an inner module and a light source. The outer module is used to be arranged outside the two pipe segments, the inner module is used to be arranged inside the two pipe segments, the light source is arranged on one side of the outer module away from the outside of the pipe segment. The outer module includes an outer polarizer and an outer quarter-wave plate from outside to inside. The outer module is semi-cylindrical, and the axis of the outer module is parallel to the corresponding pipe segment. The inner module successively includes a photosensitive screen, an inner analyzer, an inner quarter-wave plate, an eyepiece and an objective lens from outside to inside. The photosensitive screen, the inner analyzer and the inner quarter-wave plate are all semi-cylindrical; A recording system, which is used to obtain the interference fringes obtained by the photosensitive screen and the magnitude of the force applied by the loading component; The three-dimensional photoelastic testing method for pipe segments includes: S10. Fix the two inner modules in the two pipe segments respectively; S20. Insert the two pipe segments into the model box from one end of the model box and abut them. The two pipe segments form an included angle between their axes. Fill the model box with transparent soil at a preset temperature, and the transparent soil applies different preset loads to the two pipe segments; S30. Fix the two outer modules and the light source outside the model box respectively, and ensure that the bending directions of the inner module and the outer module of the same pipe segment are opposite; S40. Turn on the loading component, apply a loading force to the end of the pipe segment exposed outside the model box, and obtain the interference fringes on the photosensitive screen for the first time; S50. Rotate the inner module and the outer module 180° inside and outside their respective pipe segments, apply the same loading force to the same pipe segment in S40, and obtain the interference fringes on the photosensitive screen for the second time; S60. splice the interference fringes obtained twice to obtain complete interference fringes, and analyze the stress field distribution of the pipe segment based on the complete interference fringes, the loading force, the load and the temperature.

2. The three-dimensional photoelastic testing method for pipe segments according to claim 1, wherein: A pipe passing hole is arranged on the side wall of the model box, and the diameter of the pipe passing hole is larger than the diameter of the pipe segment. The pipe segments respectively pass through the pipe passing hole and abut inside the model box.

3. The three-dimensional photoelastic testing method for pipe sections according to claim 1, characterized in that: The loading component further includes a reaction frame and a jack. The jack is arranged on the reaction frame. The jack is arranged at one end of the pipe segment exposed outside the model box and acts on the end of the pipe segment. A pressure sensor is arranged between the jack and the abutting pipe segment.

4. The three-dimensional photoelastic test method for pipe sections according to claim 3, characterized in that: The recording system includes a PC terminal and a digital display instrument. The digital display instrument is used to obtain the magnitude of the loading force of the pressure sensor, and the digital display instrument and the photosensitive screen are respectively connected to the PC terminal in signal.

5. The three-dimensional photoelastic testing method for pipe segments according to claim 1, wherein: Both the pipe segment and the model box are made of transparent materials.

6. The three-dimensional photoelastic test method for pipe sections according to claim 1, wherein: The three-dimensional photoelastic testing method for pipe segments further includes step S70. In step S70, at least one of the included angle between the axes, the magnitude of the load, the magnitude of the loading force and the temperature of the transparent soil is changed, and steps S10-S60 are repeated.

7. The three-dimensional photoelastic test method for pipe segments according to claim 1, characterized in that: The angular range of the included angle between the axes is 0-10°.

8. The three-dimensional photoelastic testing method for pipe sections according to claim 1, characterized in that: Pour transparent soil into the model box, and bury the transparent soil to different depths of the pipe section to form different loads.

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