Supergravity transparency physical simulation test equipment

Abstract

The invention discloses super-gravity transparent physical simulation test equipment which comprises a super-gravity centrifugal machine for providing a super-gravity environment for a transparent soil test and a transparent soil model test device. The transparent soil model test device comprises an experiment cabin, a transparent soil model box, a stand column, a cross beam, an imaging system, a loading system and an automatic control and data image processing system. The experiment cabin is of a hexahedron structure with an opening in the top face, and the transparent soil model box is placed in the center of the cabin bottom. The four stand columns are arranged at the four corners of the cabin bottom face, and cross beams are arranged at the upper ends of the stand columns. An imaging system and a loading system are carried on the cross beam, the imaging system comprises a sliding groove, a telescopic rod, a CCD camera and a laser, and the loading system comprises a loader, a servo actuator and a transparent soil loading arm. The automatic control and data image processing system is used for adjusting the position of the sliding groove, the length of the telescopic rod and the position and power of the servo actuator and processing speckle images collected at different moments and different sections.

Description

Technical Field

[0001] The invention relates to the technical field of transparent soil testing, in particular to a hypergravity transparency physical simulation testing device. Background Art

[0002] As an important geotechnical engineering physical simulation technology, transparent soil model testing has played an important role in recent years in the fields of soil deformation, seepage, pile foundation bearing, and geological disaster mechanism research. Traditional transparent soil materials match the refractive index to make the optical properties of soil particles and pore fluids consistent, thereby enabling visual observation of the deformation and failure process inside the soil. However, most existing transparent soil testing equipment is carried out under a 1g gravity field (conventional gravity). Due to the scale effect, it is difficult to accurately simulate the stress state and deformation characteristics of the soil in actual engineering. The scale effect causes the stress level of the model test to be much lower than that of the prototype, resulting in significant deviations in the mechanical response of the soil (such as strength, deformation modulus, and failure mode), which seriously restricts the engineering guidance value of the test results. In addition, conventional transparent soil testing relies on manual operation, with low data acquisition efficiency and susceptibility to subjective interference. Especially in complex stress paths or multi-field coupling tests, it is difficult to achieve high-precision and repeatable automated control.

[0003] To address the scaling effect, transparent soil technology has been combined with a high-gravity centrifuge. This approach uses a high-gravity environment (ng condition, where n is the centrifugal acceleration coefficient) to increase the self-weight stress of the model soil, making it equivalent to the prototype stress field. However, existing high-gravity transparent soil testing systems face two major technical bottlenecks. First, under high-speed rotation in high gravity, traditional optical observation systems suffer from image distortion due to vibration and off-axis offset, making it difficult to stably obtain internal deformation data of the transparent soil. Second, the test loading, data acquisition, and real-time analysis lack integrated automated control, making them unable to adapt to the rapid switching and precise control of multiple operating parameters (such as seepage-stress coupling and dynamic loading). Summary of the Invention

[0004] The purpose of the present invention is to provide a hypergravity transparency physical simulation test equipment, which includes a hypergravity centrifuge and a transparent soil model test device.

[0005] The transparent soil model test device comprises an experimental cabin, a transparent soil model box, columns, beams, an imaging system, a loading system, and an automatic control and data image processing system.

[0006] The experimental cabin is a hexahedral structure with an open top. The transparent soil model box is located in the cabin and placed at the center of the bottom of the experimental cabin. Four columns are arranged around the transparent soil model box at the four corners of the bottom of the experimental cabin, and a U-shaped cross beam is provided at the end of the column away from the bottom of the cabin.

[0007] The crossbeams include crossbeam I, crossbeam II, crossbeam III and crossbeam IV which are vertically connected in sequence. Slide rail I is provided on the outer side walls of crossbeam I, crossbeam II, crossbeam III and crossbeam IV, and slide rail II is also provided on the top surfaces of crossbeam I and crossbeam III.

[0008] The imaging system includes four slide slots, four telescopic rods, two CCD cameras and two lasers.

[0009] The fixed ends of the four telescopic rods are respectively connected to the four slide slots, and the movable ends are respectively connected to the two CCD cameras and the two lasers.

[0010] The four slide grooves are respectively slidably connected to the four slide rails.

[0011] The CCD camera and the laser are arranged opposite to each other, and the lenses are both facing the transparent soil model box.

[0012] The loading system comprises a loader, a servo actuator and a transparent soil loading arm with two ends slidingly connected to a crossbeam I and a crossbeam III slide rail II.

[0013] A slide rail III is provided on the side wall of the transparent soil loading arm, and the servo actuator is slidably connected to the slide rail III.

[0014] The servo actuator is connected to the loader and is used to control the loader to move up and down so that the loader acts on the transparent soil in the transparent soil model box.

[0015] The automatic control and data image processing system is used to adjust the position of the slide, the length of the telescopic rod, the position and power of the servo actuator, and to process the speckle images collected at different times and sections.

[0016] The experimental cabin is arranged at the test end of the rotating arm of the ultra-gravity centrifuge, and the ultra-gravity centrifuge is used to provide an ultra-gravity environment for transparent soil testing.

[0017] Furthermore, the crossbeam is arranged above the transparent soil model box.

[0018] Furthermore, the width of the crossbeam is greater than the cross-sectional dimension of the column, so that the column is wrapped inside the crossbeam.

[0019] Furthermore, the column is made of aluminum alloy or rigid material and has a diameter of 8-10 cm.

[0020] Furthermore, the crossbeam is made of aluminum alloy or rigid material and has a thickness of 5-8 cm.

[0021] Furthermore, the telescopic rod is made of aluminum alloy or rigid material.

[0022] Furthermore, the hypergravity experiment cabin includes a bottom plate and a cabin wall.

[0023] The bottom plate and the bulkhead are both made of aluminum alloy or rigid material.

[0024] Furthermore, the ultra-gravity centrifuge includes a counterweight, a rotating arm, a centrifugal rotating shaft, an ultra-gravity base, a power device, a power device base, a hanging basket and a test box rotating shaft.

[0025] A centrifugal shaft is provided on the supergravity base, a rotating arm is provided on the centrifugal shaft, one end of the rotating arm is a counterweight end loaded with a counterweight body, and the other end is a test end loaded with a hanging basket.

[0026] The experimental cabin is arranged on the hanging basket.

[0027] The supergravity base is equipped with a supergravity base, and the supergravity base is equipped with a power device for providing power to the centrifugal shaft.

[0028] Furthermore, the test end of the rotating arm is provided with a groove with the notch facing outward, and two connecting blocks are arranged opposite to each other on the end surface of the test end.

[0029] The connecting block is provided with a through hole I.

[0030] Through holes II are provided at both ends of the hanging basket.

[0031] The test box rotating shaft passes through through hole I and through hole II, and the hanging basket is fixed on the rotating arm.

[0032] Furthermore, the axes of the through hole I and the through hole II are on the same straight line.

[0033] The technical effects of the present invention are unquestionable, and the beneficial effects of the present invention are as follows:

[0034] This invention proposes a hypergravity transparency physical simulation test device. Through the innovative design of a hypergravity-optical system collaborative stabilization mechanism and a multimodal automated control platform, it achieves realistic reproduction of the stress and deformation fields of transparent soil tests under hypergravity environments and integrated full-process operation. This device not only overcomes the limitations of scale effects on model test accuracy but also provides an efficient and reliable research tool for hypergravity physical simulation in geotechnical engineering. It has important application value in disaster prevention and control for major projects such as deep earth development, submarine tunnels, and high dam slopes. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a three-dimensional schematic diagram of the hypergravity transparency physical simulation test equipment;

[0036] Figure 2 This is a three-dimensional schematic diagram of the internal structure of the centrifuge experimental chamber;

[0037] Figure 3 Schematic diagram of the transparent soil image acquisition and loading device.

[0038] In the figure: experimental cabin 1; automatic control and data image processing system 101; bulkhead 102; loader 103; servo actuator 104; column 105; telescopic rod 106; CCD camera 108; laser 109; beam 110; slide rail I 1101; slide rail II 1102; transparent soil loading arm 111; slide chute 112; transparent soil 113; transparent soil model box 114; bottom plate 115; counterweight 2; rotating arm 3; connecting block 301; centrifugal shaft 4; supergravity base 5; power unit 6; power unit base 7; hanging basket 8; test chamber shaft 9. DETAILED DESCRIPTION

[0039] The present invention will be further described below with reference to the following examples, but it should not be understood that the scope of the present invention is limited to the following examples. Without departing from the above technical ideas of the present invention, various substitutions and modifications can be made according to common technical knowledge and customary means in the art, and all should be included in the scope of protection of the present invention.

[0040] Example 1:

[0041] See also Figure 2 、 Figure 3 , a hypergravity transparency physical simulation test equipment, including a hypergravity centrifuge and a transparent soil model test device.

[0042] The transparent soil model test device includes an experimental cabin 1, a transparent soil model box 114, columns 105, beams 110, an imaging system, a loading system and an automatic control and data image processing system 101.

[0043] The experimental cabin 1 is a hexahedral structure with an open top. The transparent soil model box 114 is located in the cabin and placed at the center of the bottom of the experimental cabin. Four columns 105 are arranged at the four corners of the bottom of the experimental cabin around the transparent soil model box 114, and a U-shaped cross beam 110 is provided at the end of the column 105 away from the bottom of the cabin.

[0044] The crossbeam 110 includes crossbeam I, crossbeam II, crossbeam III and crossbeam IV which are vertically connected in sequence. Slide rails I 1101 are provided on the outer walls of crossbeams I, crossbeam II, crossbeam III and crossbeam IV, and slide rails II 1102 are also provided on the top surfaces of crossbeams I and beam III.

[0045] The imaging system includes four slide slots 112 , four telescopic rods 106 , two CCD cameras 108 and two lasers 109 .

[0046] The fixed ends of the four telescopic rods 106 are respectively connected to the four slide slots 112 , and the movable ends are respectively connected to the two CCD cameras 108 and the two lasers 109 .

[0047] The four sliding grooves 112 are slidably connected to the four sliding rails 1101 respectively.

[0048] The CCD camera 108 and the laser 109 are arranged opposite to each other, and their lenses are both facing the transparent soil model box 114.

[0049] The loading system includes a loader 103, a servo actuator 104 and a transparent soil loading arm 111 with both ends slidingly connected to the crossbeam I and the crossbeam III slide rail II 1102.

[0050] A slide rail III is provided on the side wall of the transparent soil loading arm 111 , and the servo actuator 104 is slidably connected to the slide rail III.

[0051] The servo actuator 104 is connected to the loader 103 and is used to control the loader 103 to move up and down so that the loader 103 acts on the transparent soil 113 in the transparent soil model box 114 .

[0052] The automatic control and data image processing system 101 is used to adjust the position of the slide 112, the length of the telescopic rod 106, the position and power of the servo actuator 104, and process the speckle images collected at different times and sections.

[0053] The experimental chamber 1 is arranged at the test end of the rotating arm of the ultra-gravity centrifuge, and the ultra-gravity centrifuge is used to provide an ultra-gravity environment for transparent soil testing.

[0054] Example 2:

[0055] The main structure of this embodiment is the same as that of embodiment 1. Figure 2 The crossbeam 110 is arranged above the transparent soil model box 114 .

[0056] Example 3:

[0057] The main structure of this embodiment is the same as any one of embodiments 1 to 2. Figure 3 The width of the crossbeam 110 is greater than the cross-sectional size of the column 105 so as to wrap the column 105 inside the crossbeam 110 .

[0058] Example 4:

[0059] The main structure of this embodiment is the same as any one of Embodiments 1 to 3. Furthermore, the column 105 is made of high-strength rigid materials such as 7075 aluminum alloy and low-alloy high-strength steel, and has a diameter of 8-10 cm.

[0060] Example 5:

[0061] The main structure of this embodiment is the same as any one of Embodiments 1 to 4. Furthermore, the crossbeam 110 is made of high-strength rigid materials such as 7075 aluminum alloy and low-alloy high-strength steel, and has a thickness of 5-8 cm.

[0062] Example 6:

[0063] The main structure of this embodiment is the same as any one of Embodiments 1 to 5. Furthermore, the telescopic rod 106 is made of high-strength rigid materials such as 7075 aluminum alloy and low-alloy high-strength steel.

[0064] Example 7:

[0065] The main structure of this embodiment is the same as any one of Embodiments 1 to 6. Furthermore, the hypergravity experiment chamber 1 includes a bottom plate 115 and a cabin wall 102 .

[0066] The bottom plate 115 and the bulkhead 102 are both made of high-strength rigid materials such as 7075 aluminum alloy and low-alloy high-strength steel.

[0067] Example 8:

[0068] The main structure of this embodiment is the same as any one of embodiments 1 to 7. Figure 1 The ultragravity centrifuge includes a counterweight body 2, a rotating arm 3, a centrifugal shaft 4, an ultragravity base 5, a power device 6, a power device base 7, a hanging basket 8 and a test box shaft 9.

[0069] A centrifugal shaft 4 is provided on the supergravity base 5 , and a rotating arm 3 is provided on the centrifugal shaft 4 . One end of the rotating arm 3 is a counterweight end loaded with a counterweight body 2 , and the other end is a test end loaded with a hanging basket 8 .

[0070] The experimental cabin 1 is arranged on a hanging basket 8 .

[0071] The supergravity base 5 is equipped with a supergravity base 5 , and the supergravity base 5 is equipped with a power device 6 for providing power to the centrifugal shaft 4 .

[0072] Example 9:

[0073] The main structure of this embodiment is the same as that of embodiment 8. Figure 1 The test end of the rotating arm 3 is provided with a groove with the notch facing outward, and two connecting blocks 301 are arranged opposite to each other on the end surface of the test end.

[0074] The connecting block 301 is provided with a through hole I.

[0075] Through holes II are provided at both ends of the hanging basket 8.

[0076] The test box rotating shaft 9 passes through the through hole I and the through hole II to fix the hanging basket 8 on the rotating arm 3.

[0077] Example 10:

[0078] The main structure of this embodiment is the same as any one of embodiments 8 to 9. Figure 1 , the axes of the through hole I and the through hole II are on the same straight line.

[0079] Example 11:

[0080] The main structure of this embodiment is the same as any one of the embodiments 1 to 10. Furthermore, a hypergravity transparency physical simulation test device includes a hypergravity system and a transparent soil automatic loading, image acquisition and data processing system.

[0081] The hypergravity system includes a hypergravity experimental cabin, a hypergravity counterweight, a hypergravity rotating arm, a hypergravity rotating shaft, a hypergravity base, a hypergravity power device, a power device base, a hypergravity hanging basket, a test box rotating shaft, an automatic control and data image processing system and other devices.

[0082] The supergravity hanging basket can be rotated along the test box rotating shaft through the test box rotating shaft and the supergravity rotating arm. During the test, the supergravity experimental cabin is fixedly installed on the upper part of the supergravity hanging basket, so that the supergravity experimental cabin and the supergravity hanging basket rotate around the test box rotating shaft under the power of the supergravity power device.

[0083] The supergravity base is directly connected to the supergravity rotating shaft, and a supergravity rotating arm is installed on the upper part, allowing the supergravity rotating arm to rotate in a plane around the supergravity rotating shaft. A power device base is installed on the bottom surface of the supergravity base, and a supergravity power device is arranged on the upper part of the power device base to provide power for the equipment during the supergravity test.

[0084] One end of the hypergravity rotating arm in the hypergravity system is connected to the hypergravity experimental cabin, and the other end is connected to the hypergravity counterweight to ensure that the weight of the two sections is balanced in the hypergravity environment when the hypergravity system rotates.

[0085] The transparent soil automatic loading, image acquisition and data processing system comprises a hypergravity experiment cabin, an automatic control and data image processing system and other devices.

[0086] The hypergravity experiment chamber is provided with a transparent soil model box, the interior of the model box is filled with prepared transparent sand or transparent clay material, four high-strength stainless steel columns are provided inside the hypergravity experiment chamber and are rigidly connected to the bottom of the experiment chamber, the upper part of the columns is fixedly connected to the acquisition system truss, and two laser horizontal movement tracks and two CCD camera horizontal movement tracks are respectively provided around the truss, and the tracks are respectively connected to the CCD camera plane moving device and the laser plane moving device, and the CCD camera plane moving device and the laser plane moving device can move in plane along their respective tracks.

[0087] The lower part of the CCD camera plane moving device is rigidly connected to the CCD camera vertical adjustment rod, the bottom of the CCD camera vertical adjustment rod is connected to the CCD camera, and the CCD camera vertical adjustment rod is set to a telescopic structure to ensure that the CCD camera can move up and down as needed.

[0088] The lower part of the laser camera plane moving device is rigidly connected to the laser vertical adjustment rod, and the bottom of the laser vertical adjustment rod is connected to the laser. The laser vertical adjustment rod is set as a telescopic structure to ensure that the laser can move up and down as needed.

[0089] The transparent soil loading arm is installed on the upper part of the acquisition system truss. A slide rail is arranged on the upper surface of the acquisition system truss, which allows the transparent soil loading arm to move in a plane along the slide rail. A servo actuator track is arranged on one side of the transparent soil loading arm and is connected to the servo actuator, so that the servo actuator can move along the servo actuator track. A loader is arranged on the servo actuator, so that the loader can move up and down under the power of the servo actuator, thereby realizing the loading of transparent soil pile foundation penetration, pull-out and other tests under supergravity conditions.

[0090] Furthermore, the hypergravity experiment cabin is made of high-strength steel with a thickness of 5-8 cm. Its size is customized according to the size of the hypergravity basket to ensure that the hypergravity experiment cabin can be installed on the hypergravity basket.

[0091] Furthermore, the hypergravity experiment cabin is rigidly connected to the column. The column is made of high-strength rigid material and its diameter is set to 8-10cm. The truss of the collection system on the upper part of the column is made of high-strength rigid material. Its plane size is set according to the diameter of the column. The column needs to be wrapped inside, and its thickness is set to 5-8cm. The CCD camera vertical adjustment rod and the laser vertical adjustment rod are made of high-strength rigid material to ensure that they do not deform in a hypergravity environment.

[0092] Furthermore, the servo actuator has a built-in power device that can drive the loader to load the transparent soil test, and is controlled by software in the automatic control and data image processing system.

[0093] Example 12:

[0094] The main structure of this embodiment is the same as any one of Embodiments 1 to 11. Furthermore, transparent sand or transparent clay is placed in the transparent soil model box 114.

[0095] Transparent sand is made by mixing solid particles such as fused quartz sand with pore liquids such as n-dodecane and white oil; transparent clay is made by mixing solid materials such as n-dodecane and spherical silica powder with pore liquids such as n-dodecane and white oil.

[0096] During the mixing process, the mixed material is stirred evenly to remove bubbles in the mixed material. After the preparation is completed, the prepared transparent soil sample is vacuumed to complete the preparation of the transparent soil material.

[0097] Then, the configured transparent soil 113 material is placed into the hypergravity test chamber 1. Before placing it in, the transparent soil loading arm 111 is moved to the edge to ensure that the transparent soil model box 114 can be placed in from the top and fixed to the bottom of the hypergravity test chamber 1.

[0098] Then, the transparent soil experimental cabin 1 is installed on the supergravity hanging basket 8, and the CCD camera 108, laser 109, servo actuator 104 and other equipment are connected to the automatic control and data image processing system. The CCD camera 108 and laser 109 are turned on and the position in the plane and vertical directions are adjusted through the CCD camera plane moving device, laser plane moving device, CCD camera vertical adjustment rod, and laser vertical adjustment rod until the target position is reached; the servo actuator is adjusted to the loading position on the upper part of the transparent soil model box.

[0099] The hypergravity power device is turned on to cause the centrifugal rotating arm of the hypergravity equipment to begin accelerating around the centrifugal rotating axis to the target acceleration (ng). After the acceleration stabilizes, the servo actuator is turned on to start the test. During the test, several CCD cameras and several lasers are used to collect speckle field images at different sections. During the test, the automatic control and data image processing system automatically controls and adjusts the position of the CCD camera and laser, and controls the power of the servo actuator. The speckle images collected at different times and different sections are processed using digital image processing software (PIV) to complete the test.

Claims

1. A hypergravity transparency physical simulation test device, characterized by: Includes ultra-gravity centrifuge and transparent soil model test device; The transparent soil model test device comprises an experimental cabin (1), a transparent soil model box (114), a column (105), a beam (110), an imaging system, a loading system, and an automatic control and data image processing system (101); The experimental cabin (1) is a hexahedral structure with an open top surface. A transparent soil model box (114) is located in the cabin and placed at the center of the bottom surface of the experimental cabin. Four columns (105) are arranged at four corners of the bottom surface of the experimental cabin around the transparent soil model box (114). An end of the column (105) away from the bottom of the cabin is provided with a U-shaped crossbeam (110). The crossbeam (110) comprises a crossbeam I, a crossbeam II, a crossbeam III and a crossbeam IV which are vertically connected in sequence, wherein the outer side walls of the crossbeam I, the crossbeam II, the crossbeam III and the crossbeam IV are all provided with a slide rail I (1101), and the top surfaces of the crossbeam I and the crossbeam III are also provided with a slide rail II (1102); The imaging system includes four slide slots (112), four telescopic rods (106), two CCD cameras (108) and two lasers (109); The fixed ends of the four telescopic rods (106) are respectively connected to the four slide slots (112), and the movable ends are respectively connected to the two CCD cameras (108) and the two lasers (109); The four slide grooves (112) are respectively slidably connected to the four slide rails (1101); The CCD camera (108) and the laser (109) are arranged opposite to each other, and the lenses of both cameras are facing the transparent soil model box (114); The loading system comprises a loader (103), a servo actuator (104) and a transparent soil loading arm (111) with two ends slidably connected to the crossbeam I and the crossbeam III slide rail II (1102); A slide rail III is provided on the side wall of the transparent soil loading arm (111), and the servo actuator (104) is slidably connected to the slide rail III; The servo actuator (104) is connected to the loader (103) and is used to control the loader (103) to move up and down, so that the loader (103) acts on the transparent soil (113) in the transparent soil model box (114); The automated control and data image processing system (101) is used to adjust the position of the slideway (112), the length of the telescopic rod (106), the position and power of the servo actuator (104), and to process speckle images collected at different times and sections; The experimental chamber (1) is arranged at the test end of the rotating arm of the ultra-gravity centrifuge, and the ultra-gravity centrifuge is used to provide an ultra-gravity environment for transparent soil testing.

2. The hypergravity transparency physical simulation test equipment according to claim 1, characterized in that: The crossbeam (110) is arranged above the transparent soil model box (114).

3. The hypergravity transparency physical simulation test equipment according to claim 1, characterized in that: The width of the crossbeam (110) is greater than the cross-sectional dimension of the column (105), so that the column (105) is wrapped inside the crossbeam (110).

4. The hypergravity transparency physical simulation test equipment according to claim 1, characterized in that: The pillar (105) is made of aluminum alloy or rigid material and has a diameter of 8-10 cm.

5. The hypergravity transparency physical simulation test equipment according to claim 1, characterized in that: The crossbeam (110) is made of aluminum alloy or rigid material and has a thickness of 5-8 cm.

6. The hypergravity transparency physical simulation test equipment according to claim 1, characterized in that: The telescopic rod (106) is made of aluminum alloy or rigid material.

7. The hypergravity transparency physical simulation test equipment according to claim 1, characterized in that: The hypergravity experiment cabin (1) comprises a bottom plate (115) and a cabin wall (102). The bottom plate (115) and the bulkhead (102) are both made of aluminum alloy or rigid material.

8. The hypergravity transparency physical simulation test equipment according to claim 1, characterized in that: The ultra-gravity centrifuge comprises a counterweight (2), a rotating arm (3), a centrifugal shaft (4), an ultra-gravity base (5), a power device (6), a power device base (7), a hanging basket (8) and a test chamber shaft (9); A centrifugal shaft (4) is provided on the supergravity base (5), a rotating arm (3) is provided on the centrifugal shaft (4), one end of the rotating arm (3) is a counterweight end, which is loaded with a counterweight body (2), and the other end is a test end, which is loaded with a hanging basket (8); The experimental cabin (1) is arranged on a hanging basket (8). The supergravity base (5) is equipped with a supergravity base (5), and the supergravity base (5) is equipped with a power device (6) for providing power for the centrifugal shaft (4).

9. The hypergravity transparency physical simulation test equipment according to claim 8, characterized in that: The test end of the rotating arm (3) is provided with a groove with the notch facing outward, and two connecting blocks (301) are arranged opposite to each other on the end surface of the test end; The connecting block (301) is provided with a through hole I; Through holes II are provided at both ends of the hanging basket (8); The test box rotating shaft (9) passes through the through hole I and the through hole II, and fixes the hanging basket (8) on the rotating arm (30).

10. The hypergravity transparency physical simulation test equipment according to claim 9, characterized in that: The axes of the through hole I and the through hole II are on the same straight line.

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