Pressure relief type loading and testing method for ultimate bearing capacity test of deep-sea pressure-resistant structure

Abstract

The invention relates to a deep sea pressure-resistant structure ultimate bearing capacity test pressure relief type loading and testing method, a pressure-resistant structure is a closed shell, and the method comprises the following steps: placing the pressure-resistant structure in a pressure cylinder; the pressure-resistant structure is filled with water; the space between the pressure-resistant structure and the pressure cylinder is filled with water; pressurizing: pressurizing the pressure-resistant structure filled with water and the pressure cylinder to the maximum loading pressure by adopting pressurizing equipment, wherein the maximum loading pressure is greater than or equal to the breaking pressure of the pressure-resistant structure; pressure relief: the pressure in the pressure cylinder is kept unchanged, the pressure in the pressure-resistant structure is reduced, the pressure difference between the inside and outside of the pressure-resistant structure is gradually increased, and the pressure-resistant structure is damaged until the pressure difference reaches the breaking pressure, so that shock wave energy released when the pressure-resistant structure is damaged is greatly reduced, and the test safety and the structural integrity are guaranteed; the damage position and the damage form of the test object can be conveniently judged, and valuable experimental data is provided for research on the damage mode of the pressure-resistant structure.

Description

Technical Field

[0001] The present invention relates to the technical field of deep - sea equipment testing, and in particular to a pressure - relief loading method and a testing method for the ultimate bearing capacity test of a deep - sea pressure - resistant structure. Background Art

[0002] The pressure - resistant structure is the core pressure - bearing component of deep - sea equipment to resist the huge seawater pressure underwater, and can provide a safe environment of normal temperature and pressure for personnel and equipment. When the external seawater pressure exceeds the ultimate bearing capacity of the pressure - resistant structure, the pressure - resistant structure will be damaged.

[0003] During the development of deep - sea equipment, in order to verify and find out the safety bottom line of the pressure - resistant structure, generally, an ultimate bearing capacity test study is carried out on a scaled - down model or a full - scale model of the pressure - resistant structure by using a deep - sea environment simulation test device (also called "pressure cylinder"). The currently commonly used test loading method is to place the pressure - resistant structure model in the pressure cylinder and directly apply hydrostatic external pressure to it through the pressure cylinder loading and unloading system until the model is damaged.

[0004] During the above - mentioned test process, when the pressure - resistant structure model is damaged, the closed structure is instantly damaged, and the external water quickly rushes in and squeezes the internal air. Under the action of inertia force, the air inside the pressure - resistant structure is compressed to the minimum volume and releases a powerful internal explosion shock wave outward. The larger the size of the pressure - resistant structure model and the higher the test pressure, the greater the impact energy generated by the internal explosion, which will pose a threat to the safe use of the pressure cylinder and test safety, and may cause serious safety accidents and huge economic losses.

[0005] In addition, the shock wave in the commonly used test loading method will affect the integrity of the damaged pressure - resistant structure when it is damaged. It will be difficult to accurately judge the damage position and damage form of the model after the test, which is not conducive to the research on the failure mode of the pressure - resistant structure. Summary of the Invention

[0006] The applicant of the present invention aims at the above - mentioned disadvantages in the existing production technology, and provides a pressure - relief loading method and a testing method for the ultimate bearing capacity test of a deep - sea pressure - resistant structure, thereby greatly reducing the shock wave energy released when the pressure - resistant structure is damaged, ensuring the test safety of the pressure cylinder and the integrity of the damage of the pressure - resistant structure, facilitating the judgment of the damage position and damage form of the test object, and providing valuable experimental data for the research on the failure mode of the pressure - resistant structure.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A pressure - relief loading method for the ultimate bearing capacity test of a deep - sea pressure - resistant structure, the pressure - resistant structure being a closed shell, the method comprising the following steps:

[0009] Place the pressure - resistant structure in the pressure cylinder;

[0010] Fill the inside of the pressure-resistant structure with water;

[0011] Fill the space between the pressure-resistant structure and the pressure cylinder with water;

[0012] Pressurize: Use a pressurizing device to pressurize both the pressure-resistant structure filled with water and the inside of the pressure cylinder to the maximum loading pressure, where the maximum loading pressure is greater than or equal to the failure pressure of the pressure-resistant structure;

[0013] Depressurize: Keep the pressure inside the pressure cylinder unchanged, reduce the pressure inside the pressure-resistant structure, gradually increase the pressure difference between the inside and outside of the pressure-resistant structure until the pressure difference reaches the failure pressure, and then the pressure-resistant structure fails.

[0014] As a further improvement of the above technical solution:

[0015] The pressurizing device is connected to the pressure cylinder through a pressurizing pipeline, and also includes a communication pipeline connecting the inside of the pressure cylinder and the inside of the pressure-resistant structure. A first valve is installed on the communication pipeline located outside the pressure cylinder;

[0016] During the pressurizing step, the first valve is in the open state. While the pressurizing device pressurizes the pressure cylinder through the pressurizing pipeline, the pressure inside the pressure-resistant structure increases synchronously.

[0017] It also includes a depressurizing pipeline that communicates with the inside of the pressure-resistant structure and a water storage tank located outside the pressure cylinder. A second valve is installed on the depressurizing pipeline located outside the pressure cylinder;

[0018] During the depressurizing step, the first valve is in the closed state. Keep the pressure inside the pressure cylinder unchanged, open the second valve to drain the water inside the pressure-resistant structure to the water storage tank until the pressure difference between the inside and outside of the pressure-resistant structure reaches the failure pressure.

[0019] When injecting water between the pressure-resistant structure and the pressure cylinder, both the first valve and the second valve are in the open state. After filling the inside of the pressure cylinder with water through the water injection system, continue to inject water into the pressure cylinder to discharge the air in the communication pipeline and the air in the pressure-resistant structure from the depressurizing pipeline, so that the pressure cylinder and the pressure-resistant structure are filled with water.

[0020] It also includes a first pressure sensor for detecting the pressure inside the pressure cylinder and a second pressure sensor for detecting the pressure inside the pressure-resistant structure. The first pressure sensor is electrically connected to the pressurizing control system of the pressurizing device;

[0021] The first pressure sensor, the second pressure sensor, and the second valve are electrically connected to the test control system;

[0022] In the pressure relief step, the test control system calculates the current pressure difference according to the current values of the first pressure sensor and the second pressure sensor, discharges the water in the pressure-resistant structure by controlling the opening and closing intervals of the second valve, and gradually increases the value of the pressure difference.

[0023] The pressurizing device is connected to the water reservoir.

[0024] The pressure cylinder comprises a cylinder body and a cylinder cap installed on the upper end of the cylinder body through a clamp. The cylinder body is connected to a pressurizing device through a pressurizing pipeline. The pressurizing device comprises a pressure storage cylinder connected to a water source and a pressurizing pipeline.

[0025] A method for testing the ultimate bearing capacity of a deep-sea pressure-resistant structure comprises applying an equivalent hydrostatic external pressure to the pressure-resistant structure by any of the above-mentioned loading methods until the pressure-resistant structure is damaged, then relieving the pressure in the pressure cylinder, draining the water in the pressure cylinder, taking the pressure-resistant structure out of the pressure cylinder, and then observing and analyzing the damage position and morphology of the pressure-resistant structure.

[0026] The beneficial effects of the present invention are as follows:

[0027] The present invention has a compact and reasonable structure and is easy to operate. By maintaining the pressure inside the pressure cylinder (i.e., the outside of the pressure-resistant structure) unchanged and gradually reducing the internal pressure of the pressure-resistant structure, a pressure difference is formed inside and outside the pressure-resistant structure by a pressure-relief loading method, and hydrostatic external pressure is equivalently applied to the pressure-resistant structure. Since the interior of the model is filled with water, the pressure-resistant structure will not cause serious implosion at the moment of destruction, and the internal water medium has a buffering effect on the inertial force of the pressure-resistant structure collapsing inwards at the moment of destruction, which is beneficial to ensuring the safety of the pressure cylinder test and the integrity of the pressure-resistant structure, and is convenient for judging the destruction position and destruction form of the pressure-resistant structure, providing valuable experimental data for the study of the destruction mode of the pressure-resistant structure.

[0028] At the same time, the present invention also has the following advantages:

[0029] (1) A connecting pipeline is provided to connect the pressure cylinder and the inside of the pressure-resistant structure, and the pressure cylinder and the pressure-resistant structure are connected and isolated through a first valve, so that the pressure cylinder and the pressure-resistant structure can be pressurized simultaneously using the same set of pressurizing equipment, making the loading process more convenient and ensuring that the initial internal and external pressure difference is zero.

[0030] (2) A connecting pipeline and a pressure relief pipeline are provided to connect the interior of the pressure cylinder, the interior of the pressure-resistant structure and the water reservoir. The connecting pipeline and the pressure relief pipeline are switched on and off by valves respectively, which can not only realize the pressure relief inside the pressure-resistant structure, but also can inject water and exhaust air inside the pressure-resistant structure through the pressure cylinder to ensure that the pressure cylinder and the pressure-resistant structure are filled with water, so that the pressure-resistant structure is evenly stressed during pressure relief.

[0031] (3) In this embodiment, the equivalent hydrostatic external pressure is generated by utilizing the internal and external water pressure difference for loading. When the pressure-resistant structure fails, it is not affected by the internal explosion shock wave, and the fragmentation pattern is relatively more complete. The fragmentation position and state are relatively well retained, facilitating the acquisition of the accurate crack initiation position and pattern, and being conducive to studying the bearing pressure failure mechanism of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a system diagram of the loading method of the present invention.

[0033] Figure 2 It is a schematic diagram of the pressure cylinder structure of the present invention.

[0034] Figure 3 It is a schematic diagram of the loading method of the present invention.

[0035] Figure 4 It is the process of the loading method of the present invention Figure 1 .

[0036] Figure 5 It is the process of the loading method of the present invention Figure 2 .

[0037] Figure 6 It is the process of the loading method of the present invention Figure 3 .

[0038] Wherein:

[0039] 1. Pressure cylinder; 11. Cylinder cap; 12. Clamp; 13. Cylinder body;

[0040] 2. Pressure-resistant structure;

[0041] 3. Pressurizing device; 31. Pressurizing pipeline; 32. Pressurizing control system; 33. First pressure sensor;

[0042] 4. Connecting pipeline; 41. First valve;

[0043] 5. Pressure relief pipeline; 51. Second valve; 52. Second pressure sensor;

[0044] 6. Air compressor; 7. Test control system; 8. Water reservoir. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The following will describe the detailed embodiments of the present invention with reference to the accompanying drawings.

[0046] Embodiment 1:

[0047] As Figure 1 shown, for the pressure relief type loading method for the ultimate bearing capacity test of the deep-sea pressure-resistant structure in this embodiment, the pressure-resistant structure 2 is a closed shell, and the method includes the following steps:

[0048] Place the pressure-resistant structure 2 in the pressure cylinder 1;

[0049] Fill the inside of the pressure-resistant structure 2 with water;

[0050] Fill the space between the pressure-resistant structure 2 and the pressure cylinder 1 with water;

[0051] Pressurize: Use the pressurizing device 3 to pressurize both the water-filled pressure-resistant structure 2 and the pressure cylinder 1 to the maximum loading pressure. The maximum loading pressure is greater than or equal to the failure pressure of the pressure-resistant structure 2;

[0052] Depressurize: Keep the pressure inside the pressure cylinder 1 unchanged, reduce the pressure inside the pressure-resistant structure 2, so that the pressure difference between the inside and outside of the pressure-resistant structure 2 gradually increases. Until the pressure difference reaches the failure pressure, the pressure-resistant structure 2 fails.

[0053] The pressure-resistant structure 2 is an important structure for bearing the deep-water external pressure in deep-sea equipment. It has a cavity inside, and the external wall needs to bear an external pressure of more than 50 Mpa. The inside of the pressure-resistant structure 2 is usually in an atmospheric pressure environment, and the failure pressure is the minimum external pressure that causes the pressure-resistant structure 2 to fail.

[0054] Such as Figure 1 、 Figure 2 As shown, the pressure cylinder 1 includes a cylinder body 13 and a cylinder cap 11 installed at the upper end of the cylinder body 13 through a clamp 12. The cylinder body 13 is connected to the pressurizing device 3 through a pressurizing pipeline 31. The pressurizing device 3 includes a pressure accumulator cylinder that communicates with the water source and the pressurizing pipeline 31.

[0055] The pressurizing device 3 is controlled by a pressurizing control system 32. The pressurizing control system 32 controls the pressure accumulator cylinder to pressurize the inside of the pressure cylinder 1 by detecting the pressure inside the pressure cylinder 1. In the prior art, the common method for loading the pressure-resistant structure 2 is to directly use the pressurizing device 3 to pressurize the pressure-resistant structure 2 filled with atmospheric air inside until the pressure-resistant structure 2 fails.

[0056] A water injection system can be used to inject water into the pressure cylinder 1 and the pressure-resistant structure 2. The water injection system can be a tap water pipeline.

[0057] In the loading method of this embodiment, the previous loading method of simply applying external pressure to the pressure-resistant structure 2 is changed, and a method of using the pressure difference inside and outside the pressure-resistant structure 2 is proposed to apply an equivalent hydrostatic external pressure to the pressure-resistant structure 2. Since the inside of the pressure-resistant structure 2 is filled with water, a serious implosion phenomenon will not be caused when the pressure-resistant structure 2 is damaged instantaneously, which is safer and more reliable than the direct loading method of the pressure cylinder 1, avoiding damage to the pressure cylinder 1 or seriously affecting the service life of the pressure cylinder 1 during the test, and ensuring the safety of the test equipment; the buffering effect of the water medium inside the pressure-resistant structure 2 on the inertial force of the inward collapse when the pressure-resistant structure 2 is damaged instantaneously is also conducive to maximizing the retention of the damaged position and the integrity of the structure around the damaged position, facilitating the observation and analysis of the damage position and damage form of the pressure-resistant structure 2. For the pressure-resistant structure 2 that is prone to fragmentation damage, such as the pressure-resistant structure 2 made of brittle metal materials or carbon fiber composite materials, the possibility of the pressure-resistant structure 2 being damaged and torn into pieces is reduced.

[0058] The loading method of this embodiment reduces the shock wave energy released when the test object (pressure-resistant structure 2) is damaged, ensures the test safety and the structural integrity of the test object, and improves the effectiveness, economy and safety of the test of the ultimate bearing capacity of the pressure-resistant structure of deep-sea equipment.

[0059] The loading method of this embodiment forms a pressure difference inside and outside the pressure-resistant structure 2 by maintaining the pressure inside the pressure cylinder 1 (i.e., outside the pressure-resistant structure 2) unchanged and gradually reducing the pressure inside the pressure-resistant structure 2, and equivalently applies a hydrostatic external pressure to the pressure-resistant structure 2 by means of a pressure-relief loading method. Since the inside of the model is filled with water, a serious implosion phenomenon will not be caused when the pressure-resistant structure 2 is damaged instantaneously, and the internal water medium has a buffering effect on the inertial force of the inward collapse when the pressure-resistant structure 2 is damaged instantaneously, which is conducive to ensuring the test safety of the pressure cylinder 1 and the integrity of the damage of the pressure-resistant structure 2, facilitating the judgment of the damage position and damage form of the pressure-resistant structure 2, and providing valuable experimental data for the research on the damage mode of the pressure-resistant structure 2.

[0060] Embodiment Two:

[0061] As Figure 1 shown, on the basis of Embodiment One, a connecting pipeline is added to improve the convenience of the loading method.

[0062] In order to facilitate the synchronous pressurization of the pressure cylinder 1 and the pressure-resistant structure 2, a set of pressurization equipment 3 is used to pressurize the pressure-resistant structure 2 and the pressure cylinder 1 synchronously. In the loading method of this embodiment, the pressurization equipment 3 is connected to the pressure cylinder 1 through a pressurization pipeline 31, and further includes a communication pipeline 4 connecting the inside of the pressure cylinder 1 and the inside of the pressure-resistant structure 2, and a first valve 41 is installed on the communication pipeline 4 located outside the pressure cylinder 1;

[0063] During the pressurization step, the first valve 41 is in the open state. While the pressurization device 3 pressurizes the pressure cylinder 1 through the pressurization pipeline 31, the pressure inside the pressure-resistant structure 2 increases synchronously.

[0064] Figure 3 As shown, the pressure inside the pressure cylinder 1 is P1, and the pressure inside the pressure-resistant structure 2 is P2. The process of applying an equivalent hydrostatic external pressure to the pressure-resistant structure 2 is as follows:

[0065] Pressurization step (t0 - t1): Use the pressurization device 3 to synchronously pressurize the water-filled pressure-resistant structure 2 and the pressure cylinder 1 to the maximum loading pressure Pj. The maximum loading pressure Pj is greater than or equal to the failure pressure Ps of the pressure-resistant structure 2. At t1, P1 = P2 = Pj;

[0066] Pressure relief step (t1 - t2): Keep the pressure inside the pressure cylinder 1 unchanged at the maximum loading pressure Pj, and gradually reduce the pressure inside the pressure-resistant structure 2 to make the pressure difference △P between the inside and outside of the pressure-resistant structure 2 gradually increase. △P = P1 - P2. Until the pressure difference △P reaches the failure pressure Ps, that is, at t2, the pressure-resistant structure 2 fails.

[0067] During the above loading process, the pressure difference △P is equivalent to applying a hydrostatic external pressure Pi to the pressure-resistant structure 2 for loading. When the pressure difference △P reaches the critical pressure of the ultimate bearing capacity of the pressure-resistant structure 2, that is, the failure pressure Ps, the model will fail.

[0068] A communication pipeline 4 connecting the inside of the pressure cylinder 1 and the pressure-resistant structure 2 is set, and the communication between the pressure cylinder 1 and the pressure-resistant structure 2 is realized and isolated through the first valve 41, which is convenient for using the same set of pressurization devices 3 to synchronously pressurize the pressure cylinder 1 and the pressure-resistant structure 2, making the loading process more convenient and ensuring that the initial internal and external pressure difference is zero.

[0069] In the loading method of this embodiment, a pressure relief pipeline 5 is also included. The pressure relief pipeline 5 communicates with the inside of the pressure-resistant structure 2 and a water storage tank 8 located outside the pressure cylinder 1. A second valve 51 is installed on the pressure relief pipeline 5 located outside the pressure cylinder 1;

[0070] During the pressure relief step, the first valve 41 is in the closed state, the pressure inside the pressure cylinder 1 is kept unchanged, and the second valve 51 is opened to drain the water inside the pressure-resistant structure 2 to the water storage tank 8 until the pressure difference between the inside and outside of the pressure-resistant structure 2 reaches the failure pressure.

[0071] One end of the communication pipeline 4 connecting the inside of the pressure cylinder 1 is located at the top of the pressure cylinder 1, and one end of the pressure relief pipeline 5 connecting the pressure-resistant structure 2 is located at the top of the pressure-resistant structure 2. Specifically, as Figure 1 shown, both the communication pipeline 4 and the pressure relief pipeline 5 are connected to the cylinder cap 11, which is convenient for the connection of the communication pipeline 4 and the pressure relief pipeline 5 to the pressure-resistant structure 2.

[0072] In the loading method of this embodiment, when water is injected between the pressure-resistant structure 2 and the pressure cylinder 1, the first valve 41 and the second valve 51 are both in an open state. After the pressure cylinder 1 is filled with water through the water injection system, water continues to be injected into the pressure cylinder 1 to discharge the air in the connecting pipe 4 and the air in the pressure-resistant structure 2 from the pressure relief pipe 5, so that the pressure cylinder 1 and the pressure-resistant structure 2 are filled with water.

[0073] If the pressure-resistant structure 2 is already filled with water before being placed in the pressure cylinder 1, after the pressure cylinder 1 is filled with water, further water injection is only used for exhaust;

[0074] If the pressure-resistant structure 2 is not full of water before being placed in the pressure cylinder 1 , when water flows into the pressure-resistant structure 2 from the connecting pipe 4 , water is injected into the pressure-resistant structure 2 while air in the pressure-resistant structure 2 is discharged from the pressure relief pipe 5 .

[0075] A connecting pipe 4 and a pressure relief pipe 5 are provided to connect the interior of the pressure cylinder 1, the interior of the pressure-resistant structure 2 and the water reservoir 8. The connecting pipe 4 and the pressure relief pipe 5 are switched on and off by valves respectively, which can not only realize the pressure relief inside the pressure-resistant structure 2, but also enable the pressure cylinder 1 to inject water and exhaust the air into the pressure-resistant structure 2, ensuring that the pressure cylinder 1 and the pressure-resistant structure 2 are filled with water, so that the pressure-resistant structure 2 is evenly stressed during pressure relief.

[0076] The positions where the connecting pipeline 4 and the pressure relief pipeline 5 pass through the pressure cylinder 1 are both connected watertightly to the shell through a through-tank interface, and the through-tank interface is a conventional structure.

[0077] Further, if Figure 1 As shown, it also includes a first pressure sensor 33 for detecting the internal pressure of the pressure cylinder 1, and a second pressure sensor 52 for detecting the internal pressure of the pressure-resistant structure 2, and the first pressure sensor 33 is electrically connected to the pressurization control system 32 of the pressurization device 3;

[0078] The first pressure sensor 33, the second pressure sensor 52 and the second valve 51 are electrically connected to the test control system 7;

[0079] In the pressure relief step, the test control system 7 calculates the current pressure difference according to the current values of the first pressure sensor 33 and the second pressure sensor 52, and discharges the water in the pressure-resistant structure 2 by controlling the opening and closing intervals of the second valve 51, thereby gradually increasing the value of the pressure difference.

[0080] Specifically, Figure 1 As shown, a pressure gauge is also installed on the outer shell of the pressure cylinder 1 through a pipeline, a first pressure sensor 33 is installed on the pipeline, a branch pipe is installed through a three-way joint on the pressure relief pipeline 5 between the outside of the pressure cylinder 1 and the second valve 51, a pressure gauge is installed at the end of the branch pipe, and a second pressure sensor 52 is installed on the branch pipe. The second valve 51 can be an air-controlled valve, and an air source is provided by an air compressor 6.

[0081] The first pressure sensor 33 and the second pressure sensor 52 are electrically connected to the test control system 7 through signal lines, and the pressure values can be displayed on the display screen of the test control system 7. At the same time, the pressurization control system 32 can also be integrated into the test control system 7 to facilitate the centralized control of the test equipment.

[0082] Furthermore, as Figure 1 shown, the pressurizing device 3 is connected to the water storage tank 8.

[0083] The water discharged during pressure relief is drained into the water storage tank 8, and the water storage tank 8 provides water source for the pressurizing device 3 to facilitate the recycling of water. When the pressure-resistant structure 2 is not damaged after the first loading, then after increasing the maximum loading pressure value, the pressurization and pressure relief steps are repeated until the pressure-resistant structure 2 is damaged.

[0084] Based on the conditions of the currently commonly used loading system, the loading method of this embodiment can achieve a safe and reliable ultimate bearing capacity test of the pressure-resistant structure by configuring a simple pipeline connection structure and related detection and control components.

[0085] A specific working process of the loading method of this embodiment is as follows:

[0086] Fill the pressure-resistant structure 2 with water;

[0087] Place the pressure-resistant structure 2 inside the cylinder body 13 of the pressure cylinder 1, then connect the end of the pressure relief pipeline 5 inside the cylinder cap 11 to the pressure-resistant structure 2 through a penetration interface, and at the same time connect the end of the communication pipeline 4 inside the cylinder cap 11 to the pressure-resistant structure 2 through a penetration interface, and then connect the cylinder cap 11 to the cylinder body 13 through a clamp 12.

[0088] As Figure 4 shown, open the first valve 41 and the second valve 51 to keep the communication pipeline 4 and the pressure relief pipeline 5 unblocked. After starting the water injection system to fill the inside of the pressure cylinder 1 with water, continue to inject water into the pressure cylinder 1. Use the water injection system to discharge the air inside the pressure cylinder 1 and the pressure-resistant structure 2, and then install pressure gauges, sensors, etc.

[0089] Pressurization: Keep the first valve 41 open, close the second valve 51, and control the pressurization control system 32 to pressurize the inside of the pressure cylinder 1. The pressure inside the pressure cylinder 1 and the pressure-resistant structure 2 rises synchronously to the maximum loading pressure Pj, as Figure 5 shown;

[0090] Pressure relief: Close the first valve 41, that is, disconnect the pressure flow between the inside of the pressure-resistant structure 2 and the inside of the pressure cylinder 1, keep the pressure inside the pressure cylinder 1 unchanged, control the opening and closing of the second valve 51 by using the test program of the test control system 7, gradually relieve the pressure inside the pressure-resistant structure 2, and the pressure-relief water is discharged to the reservoir 8 through the pressure-relief pipeline 5 until the model is damaged, such as Figure 6 shown.

[0091] Embodiment 3:

[0092] For the test method of the ultimate load-bearing capacity of the deep-sea pressure-resistant structure in this embodiment, use the loading method of any of the above embodiments to apply an equivalent hydrostatic external pressure to the pressure-resistant structure 2. After the pressure-resistant structure 2 is damaged, relieve the pressure of the pressure cylinder 1, then drain the water inside the pressure cylinder 1, and take out the pressure-resistant structure 2 from the pressure cylinder 1, and then observe and analyze the damage position and form of the pressure-resistant structure 2.

[0093] When conducting the ultimate load-bearing capacity test, if using the conventional loading method, when the pressure-resistant structure 2 is damaged, the damaged position will extend from the damage point to the surrounding area, resulting in a tearing phenomenon, and the structure around the damage point will fall off. Especially for materials with poor toughness, due to the huge energy during damage, the pressure-resistant structure 2 may undergo a pulverizing damage, and the entire pressure-resistant structure 2 will be torn into fragments. This loading method cannot obtain the accurate crack initiation position and is difficult to estimate the development trend of the fracture.

[0094] In this embodiment, the equivalent hydrostatic external pressure is loaded by using the method of generating the equivalent hydrostatic external pressure by the internal and external water pressure difference. When the pressure-resistant structure 2 is damaged, it is not affected by the implosion shock wave, and the fracture form is relatively more complete, and the fracture position and state are relatively well retained, which is convenient for obtaining the accurate crack initiation position and form, and is beneficial to studying the bearing pressure failure mechanism of the structure.

[0095] The above description is an explanation of the present invention, not a limitation of the invention. The scope defined by the present invention is referred to the claims. Any form of modification can be made within the protection scope of the present invention.

Claims

1. A pressure-relieving loading method for testing the ultimate bearing capacity of a deep-sea pressure-resistant structure, characterized in that: The pressure-resistant structure (2) is a closed shell, and the method includes the following steps: Place the pressure-resistant structure (2) in the pressure cylinder (1); Fill the inside of the pressure-resistant structure (2) with water; Fill the space between the pressure-resistant structure (2) and the pressure cylinder (1) with water; Pressurize: Use the pressurizing device (3) to pressurize both the pressure-resistant structure (2) filled with water and the inside of the pressure cylinder (1) to the maximum loading pressure, and the maximum loading pressure is greater than or equal to the failure pressure of the pressure-resistant structure (2); Release pressure: Keep the pressure inside the pressure cylinder (1) unchanged, reduce the pressure inside the pressure-resistant structure (2), gradually increase the pressure difference between the inside and outside of the pressure-resistant structure (2), and until the pressure difference reaches the failure pressure, the pressure-resistant structure (2) fails.

2. The pressure relief type loading method for the ultimate bearing capacity test of the deep-sea pressure-resistant structure according to claim 1, characterized in that: The pressurizing device (3) is connected to the pressure cylinder (1) through a pressurizing pipeline (31), and further includes a communication pipeline (4) connecting the inside of the pressure cylinder (1) and the inside of the pressure-resistant structure (2), and a first valve (41) is installed on the communication pipeline (4) located outside the pressure cylinder (1); In the pressurizing step, the first valve (41) is in the open state. While the pressurizing device (3) pressurizes the pressure cylinder (1) through the pressurizing pipeline (31), the pressure inside the pressure-resistant structure (2) increases synchronously.

3. The pressure-relieving loading method for the ultimate bearing capacity test of the deep-sea pressure-resistant structure according to claim 2, characterized in that: It further includes a pressure relief pipeline (5), the pressure relief pipeline (5) communicates with the inside of the pressure-resistant structure (2) and a water storage tank (8) located outside the pressure cylinder (1), and a second valve (51) is installed on the pressure relief pipeline (5) located outside the pressure cylinder (1); In the pressure relief step, the first valve (41) is in the closed state, keep the pressure inside the pressure cylinder (1) unchanged, open the second valve (51) to drain the water inside the pressure-resistant structure (2) into the water storage tank (8) until the pressure difference between the inside and outside of the pressure-resistant structure (2) reaches the failure pressure.

4. The pressure relief type loading method for the ultimate bearing capacity test of the deep-sea pressure-resistant structure according to claim 3, wherein: When injecting water between the pressure-resistant structure (2) and the pressure cylinder (1), both the first valve (41) and the second valve (51) are in the open state. After filling the inside of the pressure cylinder (1) with water through the water injection system, continue to inject water into the pressure cylinder (1) to discharge the air in the communication pipeline (4) and the air in the pressure-resistant structure (2) from the pressure relief pipeline (5), so that the pressure cylinder (1) and the pressure-resistant structure (2) are filled with water.

5. The pressure relief type loading method for the ultimate bearing capacity test of the deep-sea pressure-resistant structure according to claim 3, characterized in that: It further includes a first pressure sensor (33) for detecting the pressure inside the pressure cylinder (1) and a second pressure sensor (52) for detecting the pressure inside the pressure-resistant structure (2), and the first pressure sensor (33) is electrically connected to the pressurizing control system (32) of the pressurizing device (3); The first pressure sensor (33), the second pressure sensor (52) and the second valve (51) are electrically connected to the test control system (7); In the pressure relief step, the test control system (7) calculates the current pressure difference according to the values of the current first pressure sensor (33) and the second pressure sensor (52), and discharges the water in the pressure-resistant structure (2) by controlling the opening and closing intervals of the second valve (51) to gradually increase the value of the pressure difference.

6. The pressure relief type loading method for the ultimate bearing capacity test of the deep-sea pressure-resistant structure according to claim 3, wherein: The pressurizing device (3) is connected to the water storage tank (8).

7. The pressure-relieving loading method for the ultimate load-bearing capacity test of the deep-sea pressure-resistant structure according to claim 2, characterized in that: The pressure cylinder (1) includes a cylinder body (13) and a cylinder cap (11) installed at the upper end of the cylinder body (13) through a clamp (12). The cylinder body (13) is connected to a pressurizing device (3) through a pressurizing pipeline (31). The pressurizing device (3) includes a pressure accumulator cylinder that communicates with a water source and the pressurizing pipeline (31).

8. A test method for the ultimate bearing capacity of a deep - sea pressure - resistant structure, characterized in that: Using the loading method according to any one of claims 1-7, apply an equivalent hydrostatic external pressure to the pressure-resistant structure (2). After the pressure-resistant structure (2) is damaged, relieve the pressure of the pressure cylinder (1), then drain the water in the pressure cylinder (1), take out the pressure-resistant structure (2) from the pressure cylinder (1), and then observe and analyze the damage location and form of the pressure-resistant structure (2).

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