CN214334546U - Thermal expansion type triaxial loading device - Google Patents
Thermal expansion type triaxial loading device Download PDFInfo
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- CN214334546U CN214334546U CN202120383557.3U CN202120383557U CN214334546U CN 214334546 U CN214334546 U CN 214334546U CN 202120383557 U CN202120383557 U CN 202120383557U CN 214334546 U CN214334546 U CN 214334546U
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Abstract
The utility model relates to a thermal expansion type three-axis loading device; the device comprises an upper end cover, a lower end cover, a middle thermal hoop cylinder, a heat source item, a heat insulation layer and a lower bottom plate, wherein the middle thermal hoop cylinder, in which the heat source item is arranged, is sleeved in the upper end cover, the bottom of the upper end cover is fixedly connected with the lower bottom plate, surrounding media are uniformly arranged on the inner wall of the middle thermal hoop cylinder, the outer side wall of each surrounding medium is attached to the inner wall of the middle thermal hoop cylinder, a temperature sensor and a pressure sensor are arranged in each surrounding medium, the heat insulation layer wraps the outer side of the cylinder body of the upper end cover, and the loading and unloading processes of a tested object are realized by utilizing the temperature stress generated by the surrounding media due to the temperature change; the loading of stress states such as true triaxial and conventional triaxial can be realized through the selection of surrounding media; the loading device disclosed by the invention is simple in structure, the labor intensity of personnel is reduced, and the cost is obviously reduced; the device can be applied to occasions where various materials and objects such as metal, rock and the like need high-temperature and high-pressure loading, has wide practicability, and is very suitable for popularization and application in rock mechanical tests and other related subjects.
Description
Technical Field
The utility model belongs to the technical field of mechanical test, concretely relates to heat expansion formula triaxial loading device.
Background
Mechanical tests are very common in the field of engineering technology, and in these tests, the tested object needs to be subjected to force loading, such as typical metal and rock mass material mechanical tests, and even soil body mechanical tests. Many stronger materials often require a greater load to achieve their purpose. For the existing mechanical loading experiment technology based on pump work, larger load is applied, which means larger investment. In recent years, with the continuous development of engineering construction, for example, the research on the development and utilization of deep energy resources and deep underground spaces is increasingly emphasized and promoted, many of them need to realize high stress loading, and the demand of high stress large-scale model experiments is also promoted. Therefore, how to control costs and achieve effective high stress loading to support large tests is an urgent need for many engineering mechanics studies.
In various loading test methods, specimen size is one of the determining factors. The widely used small cylindrical sample (phi 50mm x 100mm) is actually the material property of the object to be tested, and it is difficult to truly represent or simulate the "structural characteristics" of the object to be tested (such as a large rock mass). For this reason, it is often necessary to carry out so-called "model" experiments. The sample size of the model experiment is significantly increased. The reasonably designed model experiment has great value. Because the sample size is larger, the model test provides the possibility of revealing more experimental phenomena, the test result of the model test is often better similar to the actual engineering situation, and the model test is more true to the guidance of the actual engineering.
However, the load output of the test system is proportional to the square of the specimen size. For example, also when a stress of 60MPa is achieved, a load required for a cross section of 100mm × 100mm is 0.6MN, and when the specimen size is 1m × 1m × 1m, the required load increases to 60MN, which is a huge tonnage. At present, a hydraulic loading mode is generally used, so that oil cylinders and loading frames are extremely large due to the tonnage, and the manufacturing cost is extremely high. It can be seen that the application of high stress to large-size model specimens is difficult to achieve at lower cost.
Disclosure of Invention
Aiming at the problems in the prior art, the utility model provides a thermal expansion type triaxial loading device, which is a device that the temperature change is generated on the surrounding medium and the temperature stress is generated to be applied to the tested object, so as to simulate the stress condition of the tested object under different states, and the test result is always better similar to the actual engineering condition; the loading method of the utility model can realize the loading of the true triaxial, the conventional triaxial, the three-dimensional isopiestic pressure state of the tested object aiming at various materials such as metal, rock and the like, and has wide application condition; more importantly, the unloading of the force can also be achieved when the temperature of the surrounding medium decreases; device simple structure, low in labor strength, stability is high, is expected to show reduction construction cost and personnel's cost.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
a thermal expansion triaxial loading device comprising: the device comprises a surrounding medium 2, an upper end cover 31, a lower bottom plate 32, a longitudinal loading pressure head 4, a heat source item 51, a middle thermal hoop cylinder 52, a temperature control switch 6, a heat preservation layer 7, a temperature sensor and a pressure sensor; wherein the middle thermal hoop cylinder 52 with the heat source item 51 arranged in the cylinder wall is sleeved in the upper end cover 31, the bottom of the upper end cover 31 is fixedly connected with the lower bottom plate 32, four surrounding media 2 are uniformly arranged on the inner wall of the middle thermal hoop cylinder 52, the outer side wall of each surrounding medium 2 is attached to the inner wall of the middle thermal hoop cylinder 52, a temperature sensor and a pressure sensor are arranged inside each surrounding medium 2, and the heat-insulating layer 7 is wrapped outside the main cylinder body of the upper end cover 31.
The surrounding medium 2 has a thermal expansion coefficient greater than 10-7℃-1The upper end cover 31, the lower bottom plate 32, the middle thermal hoop cylinder 52 and the longitudinal loading pressure head 4 are made of materials with thermal expansion coefficients which are 0.001 times smaller than that of the surrounding medium 2.
The outer side wall of the surrounding medium 2 is a curved surface for being attached to the inner wall of the middle heat hoop cylinder 52, the outer side wall of the surrounding medium 2 is provided with a positioning strip 26, the surrounding medium 2 is connected with the positioning groove 521 on the inner wall of the middle heat hoop cylinder 52 in a matched mode through the positioning strip 26 on the outer side wall of the surrounding medium 2, the inner side wall of the surrounding medium 2 is a plane, the inner side wall of the surrounding medium 2 is provided with a groove 25, a temperature sensor and a pressure sensor are placed in the groove 25, leads of the temperature sensor and the pressure sensor extend to the upper end cover 31 along the groove 25 and penetrate out from a lead hole in the top end of the upper end cover 31.
The top end of the upper end cover 31 is provided with a square through hole, four lead holes for leading out of temperature sensors and pressure sensors are arranged on the upper end cover 31 around the square through hole, and a plurality of bolt holes are formed in the bottom skirt edge of the upper end cover 31 and used for being connected with the lower bottom plate 32.
The inner ring of the lower bottom plate 32 is provided with a plurality of vertical through holes for leading out of the heat source item 51, and the upper edge of the lower bottom plate 32 is provided with a plurality of bolt holes along the circumferential direction for connecting with the upper end cover 31.
The longitudinal loading pressure head 4 is contacted with the longitudinal end face of the tested object 1 through a square through hole at the top end of the upper end cover 31.
The heat source item 51 is an electromagnetic coil or a heating resistance wire.
Four positioning grooves 521 are uniformly arranged inside the middle heat hoop cylinder 52 and are matched with the positioning grooves 21 on the outer side wall of the surrounding medium 2, the middle heat hoop cylinder 52 is sleeved inside the upper end cover 31, and the outer side wall of the middle heat hoop cylinder 52 is attached to the inner side wall of the cylinder body of the upper end cover 31.
The utility model has the advantages that:
(1) the utility model discloses realize for the first time that environmental temperature changes and turn into the medium deformability in the periphery, and then turn into temperature stress and apply on the object under test, can realize the high stress loading and the uninstallation process of jumbo size model sample;
(2) the utility model can realize the loading and unloading of the tested object in stress states of true triaxial, conventional triaxial, biaxial, uniaxial and the like by means of selecting and selecting surrounding media, selecting materials and the like, and meet various loading requirements;
(3) Compared with the existing loading mode and device, the pressure chamber with a brand-new loading mode and a brand-new structure is equipped in the utility model, so that part of loading links can be saved, the structure of the pressure chamber is simpler, the labor intensity of personnel can be greatly reduced in actual operation, and the construction cost and the personnel cost are expected to be remarkably reduced;
(4) the utility model can replace the surrounding medium with metal or alloy material with the same or different thermal expansion coefficients according to the required temperature and stress conditions, thereby meeting the conventional triaxial or true triaxial test of large-size model samples under different temperature and stress conditions;
(5) the utility model discloses can be applied to various materials such as metal, rock and object and need the loaded occasion of high temperature high pressure, the cost is lower, and the practicality is wide, and popularization nature is strong.
Drawings
Fig. 1 is a schematic structural view of a thermal expansion type three-axis loading device according to the present invention;
fig. 2 is a schematic view of the overall structure of a thermal expansion type three-axis loading device according to the present invention;
fig. 3 is a schematic view of a partial structure in a thermal expansion type triaxial loading apparatus of the present invention;
fig. 4 is a top view of a partial structure in a thermal expansion type three-axis loading apparatus according to the present invention;
Fig. 5 is a transverse cross-sectional view of a partial structure in a thermal expansion type triaxial loading apparatus according to the present invention;
fig. 6 is a schematic structural view of a surrounding medium in the thermal expansion type triaxial loading apparatus of the present invention;
in the figure: 1 tested object, 21 first surrounding medium, 22 second surrounding medium, 23 third surrounding medium, 24 fourth surrounding medium, 25 grooves, 26 positioning strips, 31 upper end cover, 32 lower bottom plate, 4 longitudinal loading pressure head, 51 heat source item, 52 middle heat hoop cylinder, 521 positioning groove, 6 temperature control switch and 7 heat preservation layer.
Detailed Description
Example 1
A thermal expansion triaxial loading device comprising: the device comprises a surrounding medium 2, an upper end cover 31, a lower bottom plate 32, a longitudinal loading pressure head 4, a heat source item 51, a middle thermal hoop cylinder 52, a temperature control switch 6, a heat preservation layer 7, a temperature sensor and a pressure sensor; wherein the middle thermal hoop cylinder 52 with the heat source item 51 arranged in the cylinder wall is sleeved in the upper end cover 31, the bottom of the upper end cover 31 is fixedly connected with the lower bottom plate 32, 4 surrounding media 2 are uniformly arranged on the inner wall of the middle thermal hoop cylinder 52, the outer side wall of each surrounding medium 2 is attached to the inner wall of the middle thermal hoop cylinder 52, a temperature sensor and a pressure sensor are arranged inside each surrounding medium 2, and the heat preservation layer 7 is wrapped outside the main cylinder body of the upper end cover 31 and used for preserving heat and reducing heat loss.
The surrounding medium 2 has a thermal expansion coefficient greater than 10-7℃-1The upper end cover 31, the lower bottom plate 32, the middle thermal hoop cylinder 52 and the longitudinal loading pressure head 4 are made of materials with thermal expansion coefficients which are 0.001 times smaller than that of the surrounding medium 2.
The outer side wall of the surrounding medium 2 is a curved surface for being attached to the inner wall of the middle heat hoop cylinder 52, the outer side wall of the surrounding medium 2 is provided with a positioning strip 26, the surrounding medium 2 is connected with the positioning groove 521 on the inner wall of the middle heat hoop cylinder 52 in a matched mode through the positioning strip 26 on the outer side wall of the surrounding medium 2, the inner side wall of the surrounding medium 2 is a plane, the inner side wall of the surrounding medium 2 is provided with a groove 25, a temperature sensor and a pressure sensor are placed in the groove 25, leads of the temperature sensor and the pressure sensor extend to the upper end cover 31 along the groove 25 and penetrate out from a lead hole in the top end of the upper end cover 31.
The top end of the upper end cover 31 is provided with a square through hole, 4 lead holes for leading out of temperature sensors and pressure sensors are arranged on the upper end cover 31 around the square through hole, and a plurality of bolt holes are formed in the bottom skirt edge of the upper end cover 31 and used for being connected with the lower bottom plate 32.
The inner ring of the lower bottom plate 32 is provided with a plurality of vertical through holes for leading out of the heat source item 51, and the upper edge of the lower bottom plate 32 is provided with a plurality of bolt holes along the circumferential direction for connecting with the upper end cover 31.
The longitudinal loading pressure head 4 is contacted with the longitudinal end face of the tested object 1 through a square through hole at the top end of the upper end cover 31, and applies longitudinal load.
The heat source item 51 is an electromagnetic coil or a heating resistance wire, heat is directly provided, and a lead of the heat source item 51 is connected to the temperature control switch 6.
The inside 4 constant head tanks 521 that evenly arrange of middle thermal hoop section of thick bamboo 52, with the constant head tank 21 cooperation of medium 2 lateral wall on every side, inside upper end cover 31 was put to middle thermal hoop section of thick bamboo 52 cover, and the laminating of middle thermal hoop section of thick bamboo 52 lateral wall and the barrel inside wall of upper end cover 31.
The method for carrying out thermal expansion type triaxial loading by applying the thermal expansion type triaxial loading device comprises the following steps:
the method comprises the following steps: preparing a square tested object 1, and leveling and polishing the outer end face of the tested object 1;
step two: the lead of the heat source item 51 is connected to the temperature control switch 6 through the vertical through hole of the lower bottom plate 32;
step three: placing the tested object 1 obtained in the first step between the first surrounding medium 21 and the second surrounding medium 22, and respectively attaching the inner side walls of the first surrounding medium 21 and the second surrounding medium 22 to the outer end surfaces of the tested object 1 on two sides in the X direction;
respectively attaching the inner side walls of the third surrounding medium 23 and the fourth surrounding medium 24 to the outer end surfaces of the two sides of the tested object 1 in the Y direction;
Step four: manually pre-tightening, so that the inner side walls of the four surrounding media are completely attached to the outer end faces of the four sides of the tested object 1, and the outer side walls of the four surrounding media are respectively completely attached to the inner wall face of the middle thermal hoop cylinder 52;
step five: leading out temperature and pressure sensor leads through four lead holes at the top end of the upper end cover 31, and connecting the leads to an external data acquisition card;
step six: starting a temperature control switch 6, heating a heat source item 51 to enable the temperature of the heat source item to reach 80-300 ℃, enabling the tested object 1 to bear temperature stress acted by four surrounding media in the heating process, and reading data of a temperature sensor and a pressure sensor in each surrounding medium to obtain the temperature and the pressure of the tested object 1;
step seven: when the data of the temperature sensor and the pressure sensor in each surrounding medium reach the temperature and the pressure values required by the test design, the temperature and the pressure of the tested object 1 are shown to reach the requirements of the test design, the temperature control switch 6 is closed, the continuous heating is stopped, and the heat preservation is realized through the heat preservation layer 7;
step eight: adjusting the direction of a longitudinal loading pressure head 4 to enable the longitudinal loading pressure head 4 to be in contact with the middle thermal hoop cylinder 52 and the upper end face of the tested object 1 in the surrounding medium through a square through hole of the upper end cover 31, then enabling a cylinder rod of a vertical oil jack to be in contact with the longitudinal loading pressure head 4, applying gradually increased load to the tested object 1 through the longitudinal loading pressure head 4 by the cylinder rod of the vertical oil jack until the longitudinal pressure of the tested object 1 reaches the requirement of the test, and completing the triaxial loading test on the tested object 1;
Step nine: after the loading test is finished, popping up the longitudinal loading pressure head 4 to separate the longitudinal loading pressure head from the tested object 1, and removing the heat insulation layer 7;
step ten: and starting the temperature control switch 6, heating the heat source item 51 to make the temperature reach the room temperature, realizing reverse heating of the four surrounding media, when the data of the pressure sensors in the surrounding media are all zero, indicating that the pressure borne by the tested object 1 is recovered to zero, stopping heating, namely closing the temperature control switch 6, and completing the stress unloading process of the tested object 1.
If the four surrounding media in the middle thermal hoop cylinder 52 are materials with the same thermal expansion coefficient, the method is a conventional triaxial test performed on the tested object 1;
if two surrounding mediums transversely arranged oppositely in the middle thermal hoop cylinder 52 are made of materials with the same thermal expansion coefficient, two surrounding mediums 2 longitudinally arranged oppositely are made of materials with another thermal expansion coefficient value, namely the first surrounding medium 21 and the second surrounding medium 22 are made of materials with the same thermal expansion coefficient, and the third surrounding medium 23 and the fourth surrounding medium 24 are made of materials with another thermal expansion coefficient value, the method is a true triaxial loading test performed on the tested object 1.
The thermal expansion type triaxial loading method specifically comprises the following steps: wrapping the tested object 1 in the surrounding medium 2, tightly attaching the tested object to the surrounding medium 2, heating the surrounding medium 2, and limiting the deformation of the surrounding medium 2 except for the target loading direction to be zero in the heating process, so that the surrounding medium 2 generates temperature stress due to temperature change and deformation constraint and is applied to the tested object 1, and the stress loading of the tested object 1 is realized; after the loading is finished, the surrounding medium 2 is cooled down, so that the surrounding medium 2 is contracted due to temperature change and deformation, the contact with the tested object 1 is released, and the stress unloading process of the tested object 1 is realized.
The thermal expansion type three-axis loading method is characterized in that: according to different loading purposes, the loading of the temperature stress states of the tested object in a single-axis, two-way isobaric, two-way anisobaric, three-way isobaric, conventional three-axis and true three-axis states is respectively realized by means of controlling the unidirectional equal, two-way anisobaric, three-way full equal, three-way partial equal and three-way complete unequal application of the temperature stress generated by the surrounding medium 2.
The thermal expansion type three-axis loading method is characterized in that: there is no limitation on the type of the subject 1, metal or rock or concrete material.
Example 2
The utility model discloses a core thought lies in: the loading and unloading process of the tested object is realized by utilizing the temperature stress of the surrounding medium generated by the temperature change.
As shown in fig. 1 to 6, a thermal expansion type triaxial loading device includes: the heat insulation device comprises a first surrounding medium 21, a second surrounding medium 22, a third surrounding medium 23, a fourth surrounding medium 24, an upper end cover 31, a lower bottom plate 32, a longitudinal loading pressure head 4, a heat source item 51, a middle thermal hoop cylinder 52, a temperature control switch 6 and a heat insulation layer 7; the inner side walls of the first surrounding medium 21 and the second surrounding medium 22 are attached to the outer end face of the object 1 in the X direction; the inner side walls of the third surrounding medium 23 and the fourth surrounding medium 24 are attached to the outer end face of the tested object 1 in the Y direction; the inner side walls of the first surrounding medium 21, the second surrounding medium 22, the third surrounding medium 23 and the fourth surrounding medium 24 are all provided with vertical grooves 26 for placing temperature and pressure sensors; the upper end cover 31 is connected with the lower bottom plate 32 through bolts; the upper end cover 31 is provided with a square through hole with the same size and shape as the tested object 1, so that the longitudinal loading pressure head 4 can be conveniently added; the upper end cover 31 is provided with 4 lead holes, and leads of the temperature and pressure sensor are led out of the lead holes and connected with a data acquisition card; the lower bottom plate 32 is provided with a plurality of circular lead holes, and leads of the heat source item 5 are led out from the lead holes and connected with the temperature control switch 6; the middle heat hoop cylinder 52 is fixedly connected with the lower bottom plate 32; the longitudinal loading pressure head 4 is contacted with the upper end face of the tested object 1 and applies axial load; the positioning groove 521 on the inner wall surface of the middle thermal hoop cylinder 52 is overlapped with the positioning strip 26 on the outer side wall of the surrounding medium; the outer wall surface of the middle thermal hoop cylinder 52 is tightly attached to the inner wall surface of the main cylinder body of the upper end cover 31; the wall of the middle thermal hoop cylinder 52 is provided with a non-through pipeline for placing the heat source item 51; the heat-insulating layer 7 is tightly attached to the outer wall surface of the main cylinder body of the upper end cover 31 so as to reduce heat loss.
The utility model is characterized in that the first surrounding medium 21 and the second surrounding medium 22 are made of materials with the same and larger thermal expansion coefficients; the third surrounding medium 23 and the fourth surrounding medium 24 are made of materials with the same thermal expansion coefficient and larger thermal expansion coefficient; according to different loading purposes, the first surrounding medium 21, the second surrounding medium 22, the third surrounding medium 23 and the fourth surrounding medium 24 can be made of materials with the same or different thermal expansion coefficients, so that the conventional three-axis or true three-axis loading of the tested material 1 can be realized; the upper end cover 31, the lower bottom plate 32 and the middle thermal hoop cylinder 52 are made of materials with high rigidity, small deformation and thermal expansion coefficient far smaller than that of four surrounding media 2.
The utility model discloses the device temperature control switch 6 controls the intensification or the cooling of heat source item 51, and the heat evenly transmits for first surrounding medium 21, second surrounding medium 22, third surrounding medium 23, medium 24 around the fourth via middle heat hoop section of thick bamboo 52, and temperature variation makes first surrounding medium 21, second surrounding medium 22, third surrounding medium 23, medium 24 around the fourth take place to warp, simultaneously: the utility model discloses the upward deformation of first surrounding medium 21, second surrounding medium 22, third surrounding medium 23, fourth surrounding medium 24 axial of upper end cover 31 restriction, lower plate 32 restriction first surrounding medium 21, second surrounding medium 22, third surrounding medium 23, fourth surrounding medium 24 axial are downward deformed, middle heat hoop section of thick bamboo 52 restriction first surrounding medium 21, second surrounding medium 22, third surrounding medium 23, fourth surrounding medium 24 hoop outward deformation, the restraint all realizes through the face contact, so far first surrounding medium 21, second surrounding medium 22, third surrounding medium 23, fourth surrounding medium 24 deformation can only be the hoop inwards to "extrusion" subject 1, realize the loading test to subject 1; or, in the case of annealing, the first surrounding medium 21, the second surrounding medium 22, the third surrounding medium 23, and the fourth surrounding medium 24 are deformed and shrunk, and the inner side walls thereof are separated from the outer end face of the object 1, thereby realizing the unloading test of the object 1.
For better explanation of the feasibility of the invention, the following calculations were made:
(1) calculation example: true triaxial loading
The first surrounding medium 21 and the first surrounding medium 22 adopt hot-work die steel with the mark number of 4Cr5MoSiV, and the linear expansion coefficient of the hot-work die steel is 11.4 multiplied by 10 at the temperature of 20-300 DEG C-6℃-1The elastic modulus is 216000 MPa; the third surrounding medium 23 and the fourth surrounding medium 24 adopt hot-working die steel with the mark number of 4Cr5W2VSi, and the linear expansion coefficient of the hot-working die steel is 8.7 multiplied by 10 at the temperature of between 20 and 300 DEG C-6℃-1The elastic modulus is 210000 MPa; the upper end cover 31, the lower bottom plate 32 and the middle thermal hoop cylinder 52 are all made of cold-work die steel, and the thermal expansion is ignored.
Wherein ε represents the strain due to the thermal expansion of the surrounding medium, l represents the thickness of the surrounding medium, and α represents the linear expansion coefficient (deg.C) of the surrounding medium-1) E is the elastic modulus (MPa) of the surrounding medium, σ is the stress (MPa) generated by the surrounding medium, and T is the heating temperature (. degree. C.).
The following calculation is made according to equation (1): consider that the thicknesses of the first surrounding medium 21, the second surrounding medium 22, the third surrounding medium 23, and the fourth surrounding medium 24 are all 85 mm;
the stress of the first and second surrounding media 21 and 22 due to heat when heated to 300 ℃ is calculated from the formula (2):
When heated to 300 ℃, the stresses of the third surrounding medium 23 and the fourth surrounding medium 24 due to heat are calculated by formula (3):
due to sigma2＝738.72MPa≠σ3548.1MPa, therefore can think that the utility model discloses can realize true triaxial loading under prior art supports.
(2) Calculation example: conventional triaxial loading
The first surrounding medium 21, the second surrounding medium 22, the third surrounding medium 23 and the fourth surrounding medium 24 all adopt hot-work die steel with the mark number of 4Cr5MoSiV, and the linear expansion coefficient of the hot-work die steel is 11.4 multiplied by 10 at the temperature of 20 ℃ to 300 DEG C-6℃-1The elastic modulus is 216000 MPa; the upper end cover 31, the lower bottom plate 32 and the middle thermal hoop cylinder 52 are all made of cold-work die steel, and the thermal expansion is ignored.
The following calculation is made according to equation (1): consider that the thicknesses of the first surrounding medium 21, the second surrounding medium 22, the third surrounding medium 23, and the fourth surrounding medium 24 are all 85 mm;
the stress of the first and second surrounding media 21 and 22 due to heat when heated to 300 ℃ is calculated from the formula (4):
when heated to 300 ℃, the stresses of the third surrounding medium 23 and the fourth surrounding medium 24 due to heat are calculated by equation (5):
due to sigma2＝738.72MPa＝σ3738.72MPa, the utility model is considered to be in the prior art And conventional triaxial loading can be realized under the technical support.
The specific method for carrying out the model triaxial loading and unloading test by using the device comprises the following specific steps:
the method comprises the following steps: preparing a square tested object 1, and leveling and polishing the outer end face of the tested object 1;
step two: the heat source item 51 is arranged in the wall of the middle thermal hoop cylinder 52, the middle thermal hoop cylinder 52 is arranged on the lower bottom plate 32, and a lead of the heat source item 51 is connected to the temperature control switch 6 through a lead hole at the bottom of the lower bottom plate 32;
step three: the outer side wall positioning strips 26 of the first surrounding medium 21 and the second surrounding medium 22 are matched with the inner wall positioning grooves 521 of the middle thermal hoop cylinder 52;
step four: placing the temperature and pressure sensors in the inner side wall grooves 25 of the first surrounding medium 21 and the second surrounding medium 22, and leading out sensor leads from the grooves 22;
step five: placing the tested object 1 obtained in the first step between the first surrounding medium 21 and the second surrounding medium 22, and attaching the inner side walls of the first surrounding medium 21 and the second surrounding medium 22 to the outer end face of the tested object 1 in the X direction;
step six: placing the temperature and pressure sensors in the inner side wall grooves 25 of the third surrounding medium 23 and the fourth surrounding medium 24, and leading out sensor leads from the grooves 25;
Step seven: the outer side wall positioning strips 26 of the third surrounding medium 23 and the fourth surrounding medium 24 are matched with the inner wall positioning grooves 521 of the middle thermal hoop cylinder 52, and the inner side walls of the middle thermal hoop cylinder are attached to the outer end face of the tested object 1 in the Y direction;
step eight: manually pre-tightening to enable the four inner side walls of the surrounding medium to be completely attached to the outer end face of the tested object 1 and the four outer side walls of the surrounding medium to be completely attached to the inner wall face of the middle thermal hoop cylinder 52;
step nine: leading out temperature and pressure sensor leads through four lead holes at the top of the upper end cover 31, and connecting the leads to an external data acquisition card;
step ten: assembling the upper end cover 31 and the lower bottom plate 32 by using bolts to form a complete rigid system;
step eleven: the insulating layer 7 is sleeved on the outer wall of the main body cylinder of the upper end cover 31;
step twelve: starting a temperature control switch 6, heating a heat source item 51 (target: high temperature), bearing the temperature stress acted by the surrounding medium 2 on the tested object 1 in the heating process, and reading the temperature and pressure sensor data of each surrounding medium 2 to obtain the temperature and pressure of the tested object 1;
step thirteen: when the temperature and pressure sensor data of the tested object 1 reach the test design temperature and pressure values, indicating that the temperature and pressure of the tested object 1 reach the requirements of the test design, closing the temperature control switch 6, stopping continuing heating, and realizing heat preservation through the heat preservation layer 7;
Fourteen steps: adjusting the direction of a longitudinal loading pressure head 4 to enable the pressure head 4 to be in contact with the middle thermal hoop cylinder 52 and the upper end face of the tested object 1 in the surrounding medium 2 through a square through hole of the upper end cover 31, then enabling a cylinder rod of a vertical oil jack to be in contact with the pressure head 4, applying gradually increased load to the tested object 1 through the cylinder rod of the vertical oil jack until the longitudinal pressure of the tested object 1 reaches the requirement of the test, and completing a triaxial loading test on the tested object 1;
step fifteen: after the loading test is finished, popping up the longitudinal loading pressure head 4 to separate the longitudinal loading pressure head from the tested object 1;
sixthly, the steps are as follows: removing the heat-insulating layer 7, and paying attention to prevent high-temperature scalding;
seventeen steps: starting the temperature control switch 6, heating the heat source item 51 (target: low temperature), reversely heating the surrounding medium, when the pressure sensor data in each surrounding medium is zero, indicating that the pressure of the tested object 1 is recovered to zero, stopping heating, namely closing the temperature control switch 6, and completing the stress unloading process of the tested object 1.
Claims (8)
1. A thermal expansion type triaxial loading device, comprising: the device comprises a surrounding medium (2), an upper end cover (31), a lower bottom plate (32), a longitudinal loading pressure head (4), a heat source item (51), a middle thermal hoop cylinder (52), a temperature control switch (6), a heat preservation layer (7), a temperature sensor and a pressure sensor; wherein middle heat hoop section of thick bamboo (52) cover that the section of thick bamboo wall built-in heat source item (51) is put in upper end cover (31), upper end cover (31) bottom and lower plate (32) fixed connection, medium (2) around four have evenly been arranged to middle heat hoop section of thick bamboo (52) inner wall, the lateral wall of medium (2) all laminates with the inner wall of middle heat hoop section of thick bamboo (52) around every, and every medium (2) inside has all placed temperature sensor and pressure sensor around, heat preservation (7) parcel is in upper end cover (31) main part barrel outside.
2. A thermal expansion triaxial loading device according to claim 1, wherein the surrounding medium (2) has a thermal expansion coefficient greater than 10-7℃-1The upper end cover (31), the lower bottom plate (32), the middle thermal hoop cylinder (52) and the longitudinal loading pressure head (4) are made of materials with thermal expansion coefficients which are 0.001 times smaller than that of the surrounding medium (2).
3. The thermal expansion type triaxial loading device according to claim 2, wherein an outer side wall of the surrounding medium (2) is a curved surface for fitting with an inner wall of the middle thermal hoop cylinder (52), a positioning strip (26) is arranged on the outer side wall of the surrounding medium (2), the surrounding medium (2) is in fit connection with a positioning groove (521) on the inner wall of the middle thermal hoop cylinder (52) through the positioning strip (26) on the outer side wall of the surrounding medium (2), an inner side wall of the surrounding medium (2) is a plane, a groove (25) is arranged on the inner side wall of the surrounding medium (2), a temperature sensor and a pressure sensor are placed in the groove (25), leads of the temperature sensor and the pressure sensor extend to the upper end cover (31) along the groove (25) and penetrate out of a lead hole at the top end of the upper end cover (31).
4. The thermal expansion type triaxial loading device according to claim 3, wherein a square through hole is formed in the top end of the upper end cover (31), four lead holes for leading out of the temperature sensor and the pressure sensor are formed in the upper end cover (31) around the square through hole, and a plurality of bolt holes are formed in the bottom skirt of the upper end cover (31) and used for being connected with the lower base plate (32).
5. The thermal expansion triaxial loading device according to claim 4, wherein the lower base plate (32) has a plurality of vertical through holes for the lead wires of the heat source item (51) to pass through, and a plurality of bolt holes are formed in the lower base plate (32) along the circumferential direction for connecting with the upper end cap (31).
6. The thermal expansion type triaxial loading apparatus according to claim 5, wherein the longitudinal loading ram (4) is in contact with the longitudinal end face of the subject (1) through a square through hole at the top end of the upper end cap (31).
7. The thermally expanding triaxial loading device according to claim 6, wherein the heat source element (51) is an electromagnetic coil or a heating resistance wire.
8. The thermal expansion type triaxial loading device according to claim 7, wherein four positioning grooves (521) are uniformly arranged in the middle thermal hoop cylinder (52) and are matched with the positioning strips (26) on the outer side wall of the surrounding medium (2), the middle thermal hoop cylinder (52) is sleeved in the upper end cover (31), and the outer side wall of the middle thermal hoop cylinder (52) is attached to the inner side wall of the cylinder body of the upper end cover (31).
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