CN214952686U - Tensile test device for sediment containing methane hydrate - Google Patents

Abstract

The utility model provides a contain methane hydrate deposit tensile test device, including pressure-bearing storehouse, thermostated container, gas supply system, tensile system and data acquisition system. The utility model provides a contain methane hydrate deposit tensile test device, through setting up pressure-bearing storehouse and thermostated container, can simulate required low temperature and high-pressure environment of methane hydrate deposit when the seabed forms, inject into the soil sample that contains certain moisture content with methane through gas supply system in, make methane and water combination form methane hydrate and exist in soil sample hole under certain gas pressure and temperature condition, realized in the laboratory accurately simulate marine environment fast in the normal position contain the system appearance of methane hydrate soil, and then reduced the acquisition degree of difficulty and the cost of methane hydrate deposit test sample.

Description

Tensile test device for sediment containing methane hydrate

Technical Field

The utility model relates to a technical field of the physical properties test of material, in particular to contain methane hydrate deposit tensile test device.

Background

Methane hydrate (commonly called as combustible ice) is an ice-like and non-stoichiometric cage-like crystalline compound formed by absorbing gas molecules such as methane and the like into gaps of a cage-like water molecular group structure under certain pressure and temperature conditions, is widely distributed in submarine sediments and permafrost zones in land slope regions at continental borders, and has the characteristics of high combustion value, large energy, cleanness, no pollution and the like.

At present, the related research aiming at the mechanical property of the methane hydrate-containing sediment is still in the starting and exploring stages, and most laboratories adopt a triaxial test to simulate the mechanical property of the methane hydrate sediment in the actual geotechnical environment. The triaxial test is one of the most common test methods in laboratory soil test, but the following defects mainly exist when the triaxial test is applied to the test of methane hydrate sediments: firstly, methane hydrate sediments generally stably exist in deep sea sediment areas and land permafrost zones, so that the acquisition difficulty of test samples is high and the cost is high; secondly, the existing triaxial test device can only apply the ambient pressure and the axial pressure, but can not apply the force of other modes, so that the mechanical research range of the methane hydrate sediment is limited, and the development of the constitutive model is restricted.

SUMMERY OF THE UTILITY MODEL

For solving prior art, the sample that the mechanical test device of methane hydrate deposit exists acquires with high costs, the more technical problem who limits of mechanics research scope, the technical scheme of the utility model as follows:

on the one hand, the utility model provides a contain methane hydrate deposit tensile test device, including pressure-bearing storehouse, thermostated container, gas supply system, tensile system and data acquisition system.

The test device is characterized in that a dumbbell-shaped sample frame is arranged in the pressure-bearing bin and used for clamping a sample to be tested, the sample frame is formed by splicing a movable portion and a fixed portion, the fixed portion is fixed in the pressure-bearing bin, a piston hole communicated with the outside is further formed in the pressure-bearing bin, a stretching piston is inserted in the piston hole, and the movable portion is connected with the stretching piston and moves in the direction away from the fixed portion under the driving of the stretching piston.

The constant temperature box is arranged outside the pressure-bearing bin.

The gas supply system comprises a methane gas cylinder, a gas booster pump and a vacuum pump, the methane gas cylinder is connected with the gas booster pump, and the gas booster pump and the vacuum pump are respectively connected with the pressure bearing bin.

The stretching system comprises a loading pump, a hydraulic loading cylinder and a loading piston, wherein the loading pump is connected with the hydraulic loading cylinder so as to drive the loading piston in the hydraulic loading cylinder to act.

The data acquisition system comprises a processor, and a tension sensor, a displacement sensor, a temperature sensor and a first pressure sensor which are electrically connected with the processor, wherein the tension sensor is connected between the loading piston and the stretching piston, the displacement sensor is arranged on the stretching piston, and the first temperature sensor and the first pressure sensor are arranged on the pressure-bearing bin.

The utility model provides a contain methane hydrate deposit tensile test device, through setting up pressure-bearing storehouse and thermostated container, can simulate required low temperature and high-pressure environment of methane hydrate deposit when the seabed forms, inject into the soil sample that contains certain moisture content with methane through gas supply system in, make under certain gas pressure and temperature condition methane and water combine to form methane hydrate and be appeared in soil sample hole, realized in the laboratory simulation marine environment normal position contain the sample preparation of methane hydrate soil fast accurately, and then reduced the acquisition degree of difficulty and the cost of methane hydrate deposit test sample; by arranging the stretching system and the data acquisition system, the stretching test can be carried out according to different geological working conditions, so that various mechanical indexes such as tensile strength, modulus, reduction of area and the like can be obtained. The utility model provides a contain methane hydrate deposit tensile test device, its theory of operation accord with on-the-spot normal position hydrate formation mode and exploitation operating mode condition, and the structure is simple relatively, and low in cost can equip for most scientific research and reconnaissance design unit.

In one possible design, the pressure-bearing bin comprises a bin cover plate and a bin body, the bin cover plate is detachably covered on a bin opening of the bin body, and the bottom of the bin body is fixed on the test platform.

In one possible design, the gas supply system further comprises an air compressor, the air compressor is connected with the gas booster pump, and the gas booster pump provides a driving gas source.

In a possible design, a walking trolley is further arranged inside the pressure-bearing bin and comprises a supporting table and pulleys, and the sample frame is placed on the supporting table.

In a possible design, the gas supply system further comprises a gas buffer tank, a pressure regulating valve, a gas flow controller and a one-way valve, the gas buffer tank is connected between the gas booster pump and the pressure bearing bin, and the pressure regulating valve, the gas flow controller and the one-way valve are connected between the gas buffer tank and the pressure bearing bin.

In a possible design, the buffer tank is further provided with a safety valve and a second pressure sensor, and the second pressure sensor is electrically connected with the processor.

In one possible design, the device for tensile testing of methane hydrate-containing sediments of the present invention further comprises: and the gas recovery device is connected with the pressure-bearing bin.

In one possible design, the interior of the hydraulic loading cylinder is divided into a left cavity and a right cavity by the loading piston, and the left cavity and the right cavity are respectively connected with the loading pump; and a third pressure sensor is also arranged between the loading pump and the right cavity and is electrically connected with the processor.

On the other hand, the utility model also provides a tensile test method of containing methane hydrate deposit, test method is based on foretell containing methane hydrate deposit tensile test device, includes following step:

step one, forming a soil sample, namely pressing the soil sample into the sample by using a jack according to a set density, putting the pressed sample and a mould into a refrigerator for freezing, and taking out the soil sample;

step two, soil sample installation, namely installing the formed soil sample in a sample frame in a bin body, and covering a bin cover plate;

vacuumizing, starting a vacuum pump, vacuumizing the pressure-bearing bin and a connecting pipeline thereof, and removing impurities in the pressure-bearing bin;

step four, applying gas, opening the methane gas cylinder and the gas booster pump, adjusting the pressure regulating valve to regulate the pressure to a set pressure value of 6-10 Mpa, closing the methane gas cylinder and the gas booster pump, and closing the gas inlet of the pressure-bearing bin;

checking the air tightness, starting a data acquisition system and starting a constant temperature box, setting the temperature to be 18-20 ℃, maintaining the stable temperature in the pressure-bearing bin, and judging the air tightness of the pressure-bearing bin through the monitoring data change of a temperature sensor and a pressure sensor;

step six, synthesizing a hydrate-containing sample, setting the temperature of a constant temperature box to be-2 ℃, and reducing the internal temperature of the pressure-bearing bin, so that the temperature of the soil sample is reduced, the hydrate synthesis condition is achieved, and the hydrate begins to be formed in the soil sample;

step seven, judging that the synthesis of the hydrate is finished, and when the pressure value displayed by the pressure sensor I is kept stable and unchanged in the range of 3 Mpa-6 Mpa and the temperature value displayed by the temperature sensor is kept constant in the range of-2 ℃ to 2 ℃, completing the synthesis of the hydrate in the soil sample in the pressure-bearing bin and finishing the preparation of the sample;

step eight, in a tensile test, starting a loading pump to enable a loading piston to drive a tensile piston and a movable part to move, stretching a sample by the movable part, acquiring acting force of the loading piston on the tensile piston by a tension sensor, and acquiring transverse strain displacement data of the tensile piston by a displacement sensor;

and step nine, collecting gas and dismantling the sample, after the tensile test is finished, closing the loading pump, raising the temperature of the constant temperature box to 20 ℃, decomposing the hydrate of the sample, collecting the released methane through a gas recovery device, calculating the hydrate saturation of the sample according to the collection amount, and finally dismantling the sample from the sample frame.

In one possible design, in the first step, the set density of the soil sample is 1.5g/cm³～2.5g/cm³The water content is 2-40%.

The utility model provides an experimental method, better reproduction methane hydrate formation environment in the laboratory, the growth habit of simulation hydrate under the natural state to tensile strength test contains methane hydrate deposit mechanics action law and perfect corresponding constitutive model for visiting clearly and provides technical guarantee and support, also has positive impetus to china's methane hydrate commercial exploitation.

Drawings

Fig. 1 is a schematic diagram of a tensile testing apparatus for methane hydrate-containing sediments, according to an embodiment of the present invention;

fig. 2 is a schematic view of a stretching system and a bearing bin provided by an embodiment of the present invention;

FIG. 3 is a top view of the pressurized silo of FIG. 2 without the silo cover plate assembled;

fig. 4 is a schematic diagram of a sample provided by an embodiment of the present invention.

Reference numerals: 10. a pressure-bearing bin; 11. a sample frame; 111. a movable portion; 112. a fixed part; 12. a piston bore; 13. stretching the piston; 14. a support table; 15. a pulley; 16. a bin cover plate; 161. an air inlet; 162. a temperature measuring hole; 163. an air outlet; 17. a bin body; 20. a thermostat; 31. a methane cylinder; 32. a gas booster pump; 33. a vacuum pump; 34. a gas buffer tank; 341. a safety valve; 342. a second pressure sensor; 35. a pressure regulating valve; 36. a gas flow controller; 37. a one-way valve; 38. an air compressor; 41. a loading pump; 42. a hydraulic loading cylinder; 43. loading the piston; 44. a third pressure sensor; 51. a processor; 52. a tension sensor; 53. a displacement sensor; 54. a temperature sensor; 55. a first pressure sensor; 60. a gas recovery device; 70. a sample; 80. a tenth electromagnetic valve; 81. a first electromagnetic valve; 82. a second electromagnetic valve; 83. a third electromagnetic valve; 84. a fourth electromagnetic valve; 85. a fifth electromagnetic valve; 86. a sixth electromagnetic valve; 87. a seventh electromagnetic valve; 88. an eighth electromagnetic valve; 89. a ninth electromagnetic valve; 90. and (4) a test platform.

Detailed Description

The technical solution of the present invention will be described below with reference to the accompanying drawings. It is to be understood that the embodiments described are only some embodiments of the invention, and not all embodiments.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "side", "inner", "outer", "top", "bottom", and the like, indicate orientations or positional relationships based on installation, and are merely for convenience of description and simplicity of description, and do not indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the present invention.

It should be noted that, in the embodiments of the present invention, the same reference numerals are used to denote the same components or parts, and for the same components or parts in the embodiments of the present invention, only one of the components or parts may be used as an example to denote the reference numeral in the drawings, and it should be understood that the reference numerals are also applicable to other similar components or parts.

In the following, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature.

At present, a set of complete device and method for testing tensile strength of sediment containing methane hydrate are lacked. Most of the known devices for testing the tensile strength are correspondingly modified according to a conventional tensile tester, and cannot meet the working condition of simulating the submarine methane hydrate deposits to a certain extent. In addition, the lack of data on tensile strength of the methane hydrate-containing sediment restricts the development of constitutive models of the methane hydrate-containing sediment. The utility model discloses better reproduction methane hydrate formation environment in the laboratory, the growth habit of hydrate under the simulation natural state to tensile strength test, for visiting clear contain methane hydrate deposit mechanics action law and perfect corresponding constitutive model and provide technical guarantee and support, also have positive impetus to china's methane hydrate commercial exploitation.

As shown in fig. 1-3, an embodiment of the utility model provides a contain methane hydrate deposit tensile test device, including pressure-bearing storehouse 10, thermostated container 20, gas supply system, tensile system and data acquisition system, thermostated container 20 provides low temperature environment for pressure-bearing storehouse 10 in order to simulate seabed environment state, and gas supply system injects methane into in pressure-bearing storehouse 10 and makes it combine in the hole of soil sample with water, and then forms sample 70-methane hydrate deposit, and tensile system carries out tensile action to sample 70, and data acquisition system gathers test data in tensile process. The specific design of each component is as follows.

The pressure-bearing bin 10 is a rectangular parallelepiped mechanism, a dumbbell-shaped sample 70 frame 11 is arranged in the pressure-bearing bin and used for clamping a sample 70 to be tested, and the sample 70 frame 11 is formed by splicing two symmetrical frame-shaped parts, namely a movable part 111 and a fixed part 112. The fixing part 112 is fixed inside the pressure-bearing chamber 10, and when the stretching system performs stretching action, the fixing part 112 is always kept in a static state to fix one end of the sample 70; the pressure-bearing bin 10 is further provided with a piston hole 12 communicated with the outside, a stretching piston 13 is inserted in the piston hole 12, the movable part 111 is connected with the stretching piston 13, and the stretching piston 13 can axially move along the hole wall of the piston hole 12 to drive the movable part 111 to be linked together, so that the other end of the sample 70 is stretched.

The constant temperature box 20 is arranged outside the pressure-bearing bin 10, can regulate the temperature of the pressure-bearing bin 10 to simulate the low-temperature environment of the seabed, and in the stage of generating methane hydrate sediments, the constant temperature box 20 needs to provide a low-temperature environment of-2 ℃ to 2 ℃ for the pressure-bearing bin 10 and keep the temperature till the tensile test is finished, and when the test is required to be finished and methane is decomposed from a soil sample, the constant temperature box 20 needs to provide a temperature environment of 18 ℃ to 20 ℃ for the pressure-bearing bin 10.

The gas supply system comprises a methane gas cylinder 31, a gas booster pump 32 and a vacuum pump 33, wherein the methane gas cylinder 31 is connected with the gas booster pump 32, and the gas booster pump 32 and the vacuum pump 33 are respectively connected with the pressure-bearing bin 10. The gas booster pump 32 pumps the methane in the methane gas cylinder 31 into the pressure-bearing bin 10, so that the methane gas in the pressure-bearing bin 10 reaches 6-10 Mpa to simulate the high-pressure environment of the seabed, and before the methane is pumped into the pressure-bearing bin 10, the vacuum pump 33 is required to evacuate impurities in the pipeline and the pressure-bearing bin 10, so as to avoid the influence of the impurities on test data.

The stretching system comprises a loading pump 41, a hydraulic loading cylinder 42 and a loading piston 43, wherein the loading pump 41 is connected with the hydraulic loading cylinder 42 to drive the loading piston 43 in the hydraulic loading cylinder 42 to act. The loading piston 43 divides the interior of the hydraulic loading cylinder 42 into a left cavity and a right cavity, the loading pump 41 is connected with the left cavity and the right cavity respectively, when the loading pump 41 pumps liquid into the right cavity, the loading piston 43 can be pushed to move leftwards, the loading piston 43 drives the tension sensor 52, the stretching piston 13 and the movable part 111 to be linked together, and therefore the stretching system performs stretching action on the test sample 70.

The data acquisition system comprises a processor 51, and a tension sensor 52, a displacement sensor 53, a temperature sensor 54 and a pressure sensor 55 which are electrically connected with the processor 51, wherein the tension sensor 52 is connected between the loading piston 43 and the stretching piston 13, the displacement sensor 53 is arranged on the stretching piston 13, and the temperature sensor 54 and the pressure sensor are arranged on the pressure-bearing bin 10. The tension sensor 52 is connected between the loading piston 43 and the stretching piston 13, when the loading pump 41 drives the loading piston 43 to move leftward, the tension sensor 52 monitors the tension applied to the stretching piston 13, and the displacement sensor 53 monitors the displacement of the stretching piston 13, and since the stretching piston 13, the movable part 111 and the sample 70 are all in linkage relationship, the tension sensor 52 and the displacement sensor 53 also monitor the tension applied to the sample 70 and the strain displacement data synchronously. The temperature sensor 54 and the first pressure sensor 55 are both arranged on the pressure-bearing bin 10 and used for monitoring the temperature and the gas pressure in the pressure-bearing bin 10, wherein the temperature sensor 54 can be arranged inside the pressure-bearing bin 10 or in a temperature measuring hole 162, and the temperature measuring hole 162 is formed in the bin cover plate 16. The displacement sensor 53, the temperature sensor 54, the first pressure sensor 55 and the tension sensor 52 are all connected with the processor 51 through common signal wires, the processor 51 is connected with a computer through signal wires, and the real-time control and acquisition of data are realized through the computer.

The device injects methane into the samples 70 with different initial water contents and then cools the samples to prepare the samples 70 with different hydrate contents. After the sample 70 is formed, the mechanical parameters of the sample 70 can be determined by performing a tensile test on the sample 70 under a certain temperature and pressure condition. On the basis of the device, a set of method for testing the tensile mechanical parameters of the sediment containing methane hydrate is formed, and the mechanical parameters measured by the method are closer to the natural state.

The utility model discloses a preferred embodiment, close pressure-bearing storehouse 10 for switching that can be convenient to place the soil sample after the suppression in sample 70 frame 11, with the structure that pressure-bearing storehouse 10 design for can open and shut, specifically, pressure-bearing storehouse 10 includes cover plate 16 and storehouse body 17, storehouse body 17 is the cuboid structure, and the top is the cang kou, and cover plate 16 detachably covers fits the cang kou of storehouse body 17, and test platform 90 is fixed in to the bottom of storehouse body 17. Wherein, the storehouse apron 16 is connected with storehouse body 17 accessible bolt, and the junction still carries out sealing treatment, for example fills up and establishes the sealing washer, and storehouse body 17 also covers pressure-bearing storehouse 10 and test platform 90 in the lump through bolt fastening on test platform 90, thermostated container 20, carries out temperature regulation in the lump to pressure-bearing storehouse 10 and test platform 90. Wherein, the cover plate 16 is further provided with an air inlet 161 connected with an air supply system for feeding methane.

In the preferred embodiment of the present invention, because methane is a combustible gas, and there is a stricter explosion-proof requirement in the pressurizing process, the gas supply system further includes an air compressor 38, and the air compressor 38 is connected to the gas booster pump 32 to provide a driving gas source for the gas booster pump 32. Wherein, the air compressor 38 can be designed at a place far away from the methane gas cylinder 31 and the gas booster pump 32, and the high-pressure air generated by the air compressor 38 is supplied to the gas booster pump 32 through a long pipeline to be used as a driving air source of the gas booster pump 32, so as to make the gas booster pump 32 work.

In a preferred embodiment of the present invention, when performing the tensile test, the sample 70 is horizontally placed in the pressure-bearing chamber 10 through the frame 11 of the sample 70, in order to prevent the sample 70 from collapsing, the bottom of the sample 70 needs to have a supporting structure, and meanwhile, when stretching the sample 70, friction force will be generated between the sample 70 and the supporting structure, and further the test data is affected, therefore, a walking trolley is needed, and when supporting the sample 70, the friction force can be reduced to the minimum along with the movement of the sample 70. Specifically, the inside of the pressure-bearing bin 10 is also provided with a walking trolley, the walking trolley comprises a support table 14 and a pulley 15, and the support table 14 is provided with a sample 70 frame 11.

In a preferred embodiment of the present invention, in order to stably and safely operate the gas supply system, the gas supply system further includes a gas buffer tank 34, a pressure regulating valve 35, a gas flow controller 36, and a check valve 37, the gas buffer tank 34 is connected between the gas booster pump 32 and the pressure-bearing bin 10, and the pressure regulating valve 35, the gas flow controller 36, and the check valve 37 are connected between the gas buffer tank 34 and the pressure-bearing bin 10.

The buffer tank is mainly used for pressure fluctuation of a buffer system in various systems, so that the system works more stably, the buffer performance of the buffer tank is mainly realized by compressing gas in the tank, and in the embodiment, the gas buffer tank 34 is used for buffering the pressure fluctuation between the gas booster pump 32 and the pressure-bearing bin 10, so that the pressure of methane entering the pressure-bearing bin 10 is stable; the pressure regulating valve 35 is used for regulating the pressure of methane entering the pressure-bearing bin 10; the gas flow controller 36 is used for controlling the gas flow of methane and further controlling the methane gas inflow in the pressure-bearing bin 10; the check valve 37 is used to prevent methane in the pressurized cabin 10 from flowing back.

In a preferred embodiment of the present invention, in order to improve the safety of the gas buffer tank 34, prevent the risk of explosion when the gas pressure in the buffer pipe is too high, the gas buffer tank 34 is further provided with a safety valve 341 and a pressure sensor two 342, the pressure sensor two 342 is electrically connected with the processor 51, the safety valve 341 has a pressure threshold, when the gas pressure in the gas buffer tank 34 is too high, the safety valve 341 is automatically opened to release the pressure, the pressure sensor two 342 sends the pressure information in the gas buffer tank 34 to the processor 51, the real-time monitoring of the gas pressure condition of the gas buffer tank 34, if it is preset to exceed the preset value, the processor 51 sends the alarm information outwards.

In a preferred embodiment of the present invention, since methane is a combustible gas, in order to ensure safety, it is subjected to a recovery and centralized processing after the completion of the test, and at the same time, parameters are provided for calculating the saturation of the sample 70. Specifically, the tensile test apparatus for a methane hydrate-containing sediment in this embodiment further includes: and the gas recovery device 60 is connected with the pressure-bearing bin 10. The gas recovery device 60 is communicated with the pressure-bearing bin 10 through a pipeline, specifically, a gas outlet 163 is formed in the bin cover plate 16, and then the gas outlet 163 is connected with the gas recovery device 60. The gas recovery device 60 is a graduated vessel that collects the decomposition gases and also provides parameters for estimating saturation.

In a preferred embodiment of the present invention, the interior of the hydraulic loading cylinder 42 is divided into a left chamber and a right chamber by the loading piston 43, and the left chamber and the right chamber are respectively connected to the loading pump 41; and a third pressure sensor 44 is further arranged between the loading pump 41 and the right cavity, the third pressure sensor 44 is electrically connected with the processor 51, and the third pressure sensor 44 monitors the hydraulic pressure in the right cavity and measures the pressure value of the loading pump 41.

The left cavity of the hydraulic loading cylinder 42 is connected with the loading pump 41 through a three-way pipe, a five electromagnetic valve 85 and a six electromagnetic valve 86 are arranged on the three-way pipe, the five electromagnetic valve 85 controls liquid discharge, and the six electromagnetic valve 86 controls liquid inlet; correspondingly, the right cavity of the hydraulic loading cylinder 42 is also connected with the loading pump 41 through a three-way pipe, a seven electromagnetic valve 87 and an eight electromagnetic valve 88 are arranged on the three-way pipe, the eight electromagnetic valve 88 controls liquid discharge, and the seven electromagnetic valve 87 controls liquid inlet.

Wherein, the loading is performed by selecting the modes of constant pressure, stress type, strain type, etc., and the loading pump 41 is started to perform the tensile test on the sample 70.

Specifically, a first electromagnetic valve 81, a second electromagnetic valve 82, a third electromagnetic valve 83 and a fourth electromagnetic valve 84 are sequentially arranged on a connecting pipeline between the methane gas cylinder 31, the gas booster pump 32, the gas buffer tank 34, the pressure regulating valve 35, the one-way valve 37 and the pressure-bearing bin 10, a tenth electromagnetic valve 80 is arranged on a connecting pipeline between the vacuum pump 33 and the pressure-bearing bin 10, a sixth electromagnetic valve 86 and a seventh electromagnetic valve 87 are arranged on a connecting pipeline between the left cavity and the right cavity of the loading pump 41 and the hydraulic loading cylinder 42, a fifth electromagnetic valve 85 and an eighth electromagnetic valve 88 are arranged on an air outlet pipeline between the left cavity and the right cavity, and a ninth electromagnetic valve 89 is arranged on a connecting pipeline between the pressure-bearing bin 10 and the gas recovery device 60. The gas flow controller 36, the first solenoid valve 81 to the tenth solenoid valve 80 are electrically connected to the processor 51, and then the opening and closing of each pipeline is controlled in real time by the computer.

The utility model also provides a tensile test method of containing methane hydrate deposit, this test method is based on foretell containing methane hydrate deposit tensile test device.

In a preferred embodiment of the present invention, the testing method comprises the following steps:

step one, forming a soil sample, namely pressing the soil sample into the sample by a jack according to a set density, wherein the pressing die is dumbbell-shaped, and after pressing, putting the mould and the pressing die into a refrigerator for freezing and then taking out the soil sample; wherein the set density is the density of the soil of the simulated seabed methane hydrate stable layer and is 1.5-2.5 g/cm³The water content is 2-40%.

Step two, soil sample installation, namely installing the formed soil sample in the sample 70 frame 11 in the bin body 17, fixing two ends of the soil sample by the movable part 111 and the fixed part 112 respectively, connecting the bin cover plate 16 with the bin body 17 through bolts, and sealing the connection part through a sealing ring.

And step three, vacuumizing, closing the fourth electromagnetic valve 84 and the ninth electromagnetic valve 89, opening the vacuum pump 33 and the tenth electromagnetic valve 80, vacuumizing the pressure-bearing bin 10 and the connecting pipeline thereof, and removing impurities in the pressure-bearing bin.

And step four, applying gas, opening the methane gas cylinder 31, the gas booster pump 32 and the first to fourth electromagnetic valves 81 to 84, adjusting the pressure regulating valve 35 to regulate the pressure to a set pressure value of 6-10 Mpa, closing the methane gas cylinder 31, the gas booster pump 32 and the first to third electromagnetic valves 81 to 83, and simultaneously closing the gas inlet 161 of the pressure-bearing bin 10, namely closing the fourth electromagnetic valve 84.

Checking air tightness, starting a data acquisition system and starting a constant temperature box 20, and controlling the internal temperature of the pressure-bearing bin 10 after setting the temperature value to be 18-20 ℃; and monitoring and recording data changes of the temperature sensor 54 and the pressure sensor 55, and judging the air tightness of the pressure-bearing cabin 10.

Step six, synthesizing a hydrate-containing sample, setting the temperature of the constant temperature box 20 to be-2 ℃, reducing the internal temperature of the pressure-bearing bin 10, thereby reducing the temperature of the soil sample, achieving the hydrate synthesis condition, and beginning to form a hydrate in the soil sample

And step seven, judging that the synthesis of the hydrate is finished, and when the pressure value displayed by the pressure sensor I55 is kept stable and unchanged at 3 Mpa-6 Mpa and the temperature value displayed by the temperature sensor 54 is kept constant at-2 ℃, completing the synthesis of the hydrate in the soil sample in the pressure-bearing bin 10 and finishing the preparation of the sample 70.

And step eight, in the tensile test, the loading pump 41 is started to enable the loading piston 43 to drive the tensile piston 13 and the movable part 111 to move, the movable part 111 stretches the test sample 70, the tension sensor 52 collects acting force of the loading piston 43 on the tensile piston 13, and the displacement sensor 53 collects transverse strain displacement data of the tensile piston 13. Wherein, the loading in modes such as constant pressure, stress mode, strain mode, etc. can also be selected, and the loading pump 41 is started to carry out the tensile test on the sample 70.

And step nine, collecting gas and dismantling a sample, after the tensile test is finished, closing the loading pump 41, raising the temperature of the constant temperature box 20 to 20 ℃, decomposing the hydrate of the sample 70, collecting the released methane through the gas recovery device 60, calculating the saturation of the hydrate according to the collection amount, and finally dismantling the sample 70 from the frame 11 of the sample 70.

As shown in fig. 4, in a preferred embodiment of the present invention, the test specimen 70 is dumbbell-shaped, the length L1 is 240mm, the ball center distance L2 at both ends of the dumbbell is 150mm, the ball diameter D is 90mm, the L3 at the middle of the dumbbell is 50mm, and the L4 is 50 mm. That is, the dimensions of the sample 70 were the standard values when the sample 70 was subjected to the tensile test.

The above description is only for the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can easily think of the changes or substitutions within the technical scope of the present invention, and all should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (8)

1. A methane hydrate-containing sediment tensile test device is characterized by comprising:

the test device comprises a pressure-bearing bin (10), wherein a dumbbell-shaped sample frame (11) is arranged in the pressure-bearing bin and used for clamping a sample (70) to be tested, the sample frame (11) is formed by splicing a movable part (111) and a fixed part (112), the fixed part (112) is fixed in the pressure-bearing bin (10), the pressure-bearing bin (10) is further provided with a piston hole (12) communicated with the outside, a stretching piston (13) is inserted in the piston hole (12), and the movable part (111) is connected with the stretching piston (13) and moves in a direction away from the fixed part (112) under the driving of the stretching piston (13);

the constant temperature box (20) is arranged outside the pressure-bearing bin (10);

the gas supply system comprises a methane gas cylinder (31), a gas booster pump (32) and a vacuum pump (33), wherein the methane gas cylinder (31) is connected with the gas booster pump (32), and the gas booster pump (32) and the vacuum pump (33) are respectively connected with the pressure-bearing bin (10);

the stretching system comprises a loading pump (41), a hydraulic loading cylinder (42) and a loading piston (43), wherein the loading pump (41) is connected with the hydraulic loading cylinder (42) so as to drive the loading piston (43) in the hydraulic loading cylinder (42) to reciprocate;

the data acquisition system comprises a processor (51), and a tension sensor (52), a displacement sensor (53), a temperature sensor (54) and a first pressure sensor (55) which are electrically connected with the processor (51), wherein the tension sensor (52) is connected between the loading piston (43) and the stretching piston (13), the displacement sensor (53) is arranged on the stretching piston (13), and the temperature sensor (54) and the first pressure sensor (55) are both arranged on the pressure-bearing bin (10).

2. The methane hydrate-containing sediment tensile test device according to claim 1, wherein the pressure-bearing bin (10) comprises a bin cover plate (16) and a bin body (17), the bin cover plate (16) is detachably covered on a bin opening of the bin body (17), and the bottom of the bin body (17) is fixed on a test platform (90).

3. The methane hydrate-containing sediment tensile test device of claim 1, wherein the gas supply system further comprises an air compressor (38), and the air compressor (38) is connected with the gas booster pump (32) and used for providing a driving gas source for the gas booster pump (32).

4. The methane hydrate-containing sediment tensile test device according to claim 1, wherein a walking trolley is further arranged inside the pressure-bearing bin (10), the walking trolley comprises a supporting table (14) and pulleys (15), and the sample frame (11) is placed on the supporting table (14).

5. The tensile test device for sediments containing methane hydrates according to claim 1, wherein said gas supply system further comprises a gas buffer tank (34), a pressure regulating valve (35), a gas flow controller (36) and a one-way valve (37), said gas buffer tank (34) is connected between said gas booster pump (32) and said pressure-bearing bin (10), and said pressure regulating valve (35), said gas flow controller (36) and said one-way valve (37) are connected between said gas buffer tank (34) and said pressure-bearing bin (10).

6. The methane hydrate-containing sediment tensile test device according to claim 5, wherein the buffer tank is further provided with a safety valve (341) and a second pressure sensor (342), and the second pressure sensor (342) is electrically connected with the processor (51).

7. The methane hydrate-containing deposit tensile test apparatus of claim 1, further comprising:

the gas recovery device (60), the gas recovery device (60) with the pressure-bearing bin (10) is connected.

8. The methane hydrate-containing sediment tensile test device according to claim 1, wherein the interior of the hydraulic loading cylinder (42) is divided into a left cavity and a right cavity by the loading piston (43), and the left cavity and the right cavity are respectively connected with the loading pump (41); and a third pressure sensor (44) is also arranged between the loading pump (41) and the right cavity, and the third pressure sensor (44) is electrically connected with the processor (51).

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