A device and method for measuring deformation of a high-temperature and high-pressure cylindrical sample in a limited space

Abstract

The application discloses a kind of high temperature high pressure cylinder sample deformation measuring devices and methods in limited space, belong to rock mechanics experimental testing technical field, solve the sensor adaptability of existing HPHT triaxial test equipment, constrain triaxial chamber volume and the problem of high cost.The rigid measuring rod of traditional LVDT is replaced by inelastic flexible wire in the application, the volume is reduced, so that the triaxial chamber can be more miniaturized, and the first displacement sensor and the second displacement sensor are built-in in the triaxial chamber base, not only need to occupy the internal space of triaxial chamber, so that the triaxial chamber can be designed more compact, reduce the amount of confining pressure oil medium, shorten the temperature rising time, and avoid direct exposure to high temperature and high pressure environment, significantly improve its reliability in high temperature and high pressure environment, while using displacement sensor combined with inelastic flexible wire mechanical transmission scheme to replace imported special sensor, and reduce the cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rock mechanics experimental testing, and particularly relates to a device and method for measuring deformation of a cylindrical sample under high temperature and high pressure in a limited space. BACKGROUND

[0002] With the deepening of the development of deep earth resources, the research on tectonic evolution mechanism and the analysis of deep earthquake incubation mechanism, the mechanical behavior testing of rock under high geostress and high temperature (referred to as High Pressure High Temperature, HPHT) conditions has become an important direction of geological and engineering mechanics research. Rock experiences hundreds of megapascals of geostress and hundreds of degrees of stratum temperature in the deep crust, and shows complex deformation and failure characteristics such as nonlinearity, temperature-pressure coupling and time dependence. Through HPHT triaxial experiments, the mechanical response behavior of rock under extreme working conditions can be reproduced, and key information such as strength and stress-strain relationship can be obtained, thereby providing support for scientific modeling and engineering prediction.

[0003] The currently widely used HPHT triaxial experimental equipment includes the GCTS rock triaxial test system of the United States, the MTS high pressure high temperature test device, the TOP high temperature rheometer of the French Rock-Physics company, etc. These devices usually use high temperature and high pressure resistant silicone oil or other liquid pressure transmission medium to apply confining pressure to standard cylindrical rock samples (such as 100 mm high and 50 mm in diameter), and realize precise temperature control in a thermal sleeve or a heating cavity. These devices are usually large and heavy, and have high requirements for installation space; secondly, the large triaxial chamber leads to a long temperature loading and unloading process in high temperature experiments, and usually only one experiment can be completed in a day, which seriously restricts the testing efficiency. Traditional LVDT (Linear Variable Differential Transformer), resistance strain gauge and other measurement technologies have good performance in conventional triaxial experiments, for example, the LVDT differential variable displacement sensor used in the rock sample deformation measuring device and equipment with the announcement number CN212692781U, but they face the following difficulties in HPHT experiments:

[0004] 1. Insufficient adaptability to extreme environment: conventional contact type sensors (such as LVDT and strain gauge) cannot withstand confining pressures above 200 MPa and high temperatures above 200℃ for a long time, and are prone to mechanical failure or signal drift.

[0005] 2. Limitation of sensor size on testing efficiency: compared with the traditional triaxial chamber, the compact triaxial chamber requires less pressure medium, which can significantly shorten the temperature rising and falling time in high temperature experiments. However, the special sensors resistant to high temperature and high pressure (such as some piezoelectric ceramic sensors) are large in size (usually greater than 5 cm), which are difficult to embed in the compact triaxial pressure chamber, thereby restricting the realization of miniaturization of the triaxial chamber to reduce the volume and weight and improve the efficiency of high temperature experiments.

[0006] 3. High cost: Special sensors rely on imports, and the unit price can reach hundreds of thousands of yuan, which seriously restricts the popularization of high temperature and high pressure experiments.

[0007] In summary, the existing HPHT triaxial experimental equipment has the problems of insufficient sensor adaptability, restricting the volume of the triaxial chamber, and high cost. SUMMARY

[0008] In view of the above problems in the prior art, the present application provides a limited space high temperature and high pressure cylindrical sample deformation measuring device and method, which solves the problems of insufficient sensor adaptability, restricting the volume of the triaxial chamber, and high cost in the existing HPHT triaxial experimental equipment.

[0009] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0010] On the one hand, a limited space high temperature and high pressure cylindrical sample deformation measuring device is provided, which comprises an HPHT triaxial experimental equipment, and the HPHT triaxial experimental equipment at least comprises one detachable triaxial chamber, a rock sample is arranged in each triaxial chamber, and a hoop deformation measuring assembly and an axial deformation measuring assembly are arranged on the rock sample; the hoop deformation measuring assembly comprises a first pre-tightening winding device arranged on the ring surface of the rock sample, a first inelastic flexible wire is arranged around the ring surface of the rock sample in the first pre-tightening winding device, and the free end of the first inelastic flexible wire is fixedly connected with the detection end of a first displacement sensor; the axial deformation measuring assembly comprises a second inelastic flexible wire arranged vertically, one end of the second inelastic flexible wire is fixed on an axial press head in the triaxial chamber through a second pre-tightening winding device, and the other end of the second inelastic flexible wire is fixed on the detection end of a second displacement sensor; wherein the first displacement sensor and the second displacement sensor are respectively used for detecting the displacement of the first inelastic flexible wire and the second inelastic flexible wire, and the first displacement sensor and the second displacement sensor are arranged in the base of the triaxial chamber.

[0011] Further, the first displacement sensor and the second displacement sensor are structurally identical, and each includes a shell, a cavity is arranged in the shell, a third slip ring seal ring is arranged in the middle of the inner wall of the cavity, a floating disc column is slidingly sealed in the third slip ring seal ring, the upper end surface and the lower end surface of the floating disc column are fixed to the top end and the bottom end of the cavity through an upper balancing spring assembly and a lower balancing spring assembly respectively, the top end and the bottom end of the cavity are in communication with a first channel and a second channel in the shell respectively, a first slip ring seal ring and a second slip ring seal ring are arranged in the first channel and the second channel respectively, the middle part of the first slip ring seal ring and the second slip ring seal ring is slidingly and sealingly connected to the upper connecting column and the lower connecting column of the floating disc column respectively, the upper connecting column is fixedly connected to the first inelastic flexible wire or the second inelastic flexible wire, the lower connecting column is fixedly connected to the iron core, and a coil for detecting the movement signal of the iron core is arranged in the second channel; wherein, a surrounding pressure oil channel is arranged on the wall between the second slip ring seal ring and the third slip ring seal ring of the cavity, and the three-axis chamber is in communication with the surrounding pressure oil channel and the first slip ring seal ring at the upper part of the first channel.

[0012] Further, the top surface area of the upper connecting column is equal to the annular bottom surface area of the floating disc column.

[0013] Further, the floating disc column includes an initial state and a moving state; when the floating disc column is in the initial state, the floating disc column is located in the middle of the cavity, and the sum of the pre-tightening force of the first pre-tightening winder or the first pre-tightening winder and the pulling force of the upper balancing spring assembly is equal to the sum of the sinking force of the floating disc column and the pulling force of the lower balancing spring assembly.

[0014] Further, a ceramic lining is arranged on the inner wall of the second channel, and a heat insulation sheet is arranged at the connection between the lower connecting column and the iron core.

[0015] Further, a threaded structure is arranged on the outer wall of the shell, and the threaded structure is screw-connected with a sink groove in the base of the three-axis chamber.

[0016] Further, a planar sliding table is arranged on the top surface of the upper connecting column, a sliding block for sliding on the planar surface is arranged on the planar sliding table, and the sliding block is fixedly connected with the first inelastic flexible wire or the second inelastic flexible wire.

[0017] Further, the bottom of the axial pressure head and the bottom of the rock sample are respectively provided with an upper pad and a lower pad, and the annular wall of the upper pad is fixedly connected with the second pre-tightening winder through a positioning bolt.

[0018] Further, the HPHT triaxial experimental equipment further includes a carrying mechanism for moving the three-axis chamber.

[0019] On the other hand, a measurement method of a limited space high temperature high pressure cylindrical sample deformation measuring device is provided, including the following steps:

[0020] S1, the rock sample in each triaxial chamber, and the upper and lower pads on the top and bottom of the rock sample respectively are wrapped with heat shrink film as a whole, and the circumferential deformation measuring assembly and the axial deformation measuring assembly are installed;

[0021] S2, each triaxial chamber is filled with oil and heated to the target temperature, then each triaxial chamber is moved to the loading table of the HPHT triaxial test equipment in turn by the carrying mechanism, and the loading table is used to load each triaxial chamber in turn with confining pressure and axial pressure, and after loading is completed, each triaxial chamber is carried to the cooling area in turn by the carrying mechanism;

[0022] S3, the circumferential deformation and axial deformation of each rock sample are collected by the circumferential deformation measuring assembly and the axial deformation measuring assembly in each triaxial chamber.

[0023] The application discloses a limited space high-temperature and high-pressure cylindrical sample deformation measuring device and method, which has the beneficial effects that:

[0024] 1. The present application replaces the rigid measuring rod (such as the sensor support in the rock sample deformation measuring device and equipment with the announcement number CN212692781U) of the traditional LVDT with the inelastic flexible wire, which not only reduces the volume, makes the triaxial chamber more miniaturized, eliminates the measurement error caused by material thermal expansion, and meets the needs of measuring the circumferential deformation and axial deformation of the rock sample. By embedding the first displacement sensor and the second displacement sensor in the triaxial chamber base, the internal space of the triaxial chamber is not occupied, the triaxial chamber can be designed more compactly, the amount of confining pressure oil medium is reduced, the temperature rising and falling time is shortened, and the displacement sensor is directly exposed to the high-temperature and high-pressure environment, which significantly improves the reliability of the sensor in the high-temperature environment. By combining the mechanical transmission scheme of the inelastic flexible wire with the displacement sensor, the imported special sensor is replaced, and the cost is reduced.

[0025] 2. The present application ensures that the pressure inside and outside the cavity is automatically balanced through the confining pressure oil channel by arranging the floating disc cylinder, the first sliding ring seal, the second sliding ring seal and the third sliding ring seal. At the same time, the core and the coil are arranged in the second channel to isolate the interference of the confining pressure oil high temperature on the electromagnetic signal, thereby avoiding the failure of the sensor under high temperature and high pressure conditions, and further enabling the sample deformation measurement under higher temperature and higher pressure.

[0026] 3. The top surface area of the upper connecting column of the present application is equal to the annular bottom surface area of the floating disc cylinder, which ensures that the stress areas of the upper and lower end surfaces of the floating disc cylinder are consistent, avoids tilting and jamming caused by pressure difference, and improves the sensitivity of the sensor.

[0027] 4、The first pre-tightening reel or the pre-tightening force F1 of the first pre-tightening reel and the tension F2 of the upper balance spring assembly are equal to the sum of the sinking force G of the floating disc column and the tension F3 of the lower balance spring assembly, so that the floating disc column is always in a dynamic balance state and only responds to the displacement change of the wire.

[0028] 5、The heat insulation sheet and the ceramic lining are arranged in the scheme to reduce the influence of metal heat transfer on the sensor core part.

[0029] 6、The shell is connected with the base sink groove through a threaded structure in the scheme, so that the sensor can be quickly disassembled, maintained and assembled with reduced complexity.

[0030] 7、The first inelastic flexible wire and the second inelastic flexible wire will tilt during the deformation of the rock sample, which affects the detection accuracy of the first displacement sensor and the second displacement sensor, so that the connection of the first inelastic flexible wire or the second inelastic flexible wire can move through the slider on the plane sliding table, so that the first inelastic flexible wire and the second inelastic flexible wire can remain vertical under the constant pre-tightening force of the first pre-tightening reel and the second pre-tightening reel, thereby improving the circumferential deformation measurement accuracy and the axial deformation measurement accuracy.

[0031] 8、The size of the triaxial chamber is significantly reduced in the scheme, the amount of confining pressure oil medium is reduced, and the temperature rising and falling time is shortened, so that the detachable triaxial chamber cooperates with the carrying mechanism to realize the rotation loading and cooling of multiple triaxial chambers, and the number of experiments per day is increased from 1 to 4-6 times. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a structural schematic view of a triaxial chamber;

[0033] Figure 2 is a structural schematic view of a first displacement sensor;

[0034] Figure 3 is a structural schematic view of a first displacement sensor;

[0035] 1、triaxial chamber; 11、axial pressure head; 12、upper pad; 121、positioning bolt; 13、lower pad; 14、heat shrink film;

[0036] 2、circumferential deformation measurement assembly; 21、first pre-tightening reel; 22、first inelastic flexible wire; 23、first displacement sensor;

[0037] 3、axial deformation measurement assembly; 31、second pre-tightening reel; 32、second inelastic flexible wire; 33、second displacement sensor;

[0038] 4, housing; 401, screw structure; 41, cavity; 411, first channel; 412, second channel; 4121, ceramic lining; 413, confining pressure oil channel; 42, floating disc column; 421, upper connecting column; 422, lower connecting column; 43, iron core; 431, heat insulation sheet; 44, coil; 45, third sliding ring seal; 451, first sliding ring seal; 452, second sliding ring seal. DETAILED DESCRIPTION

[0039] The specific embodiments of the present application are described below to facilitate the understanding of the present application for those skilled in the art, but it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the present application defined and determined by the appended claims, and all the inventions utilizing the concept of the present application are within the scope of protection.

[0040] The present embodiment provides a structure diagram of a limited space high temperature and high pressure cylindrical sample deformation measuring device and its method, which aims to solve the problems of insufficient sensor adaptability, restricted triaxial chamber 1 volume and high cost in existing HPHT triaxial experimental equipment. The following will be described in detail.

[0041] Reference Figure 1 A limited space high temperature and high pressure cylindrical sample deformation measuring device, comprising an HPHT triaxial experimental equipment, the HPHT triaxial experimental equipment at least comprising one detachable triaxial chamber 1, each triaxial chamber 1 being provided with a rock sample, and the rock sample being provided with a hoop deformation measuring assembly 2 and an axial deformation measuring assembly 3. In the present embodiment, the triaxial chamber 1 and the heating and confining pressure structure inside the triaxial chamber 1 are all prior art, and the specific working principle and connection relationship thereof will not be described in detail.

[0042] Specifically, the hoop deformation measuring assembly 2 comprises a first pre-tightening winding device 21 arranged on the hoop surface of the rock sample, the first pre-tightening winding device 21 being provided with a first inelastic flexible wire 22 arranged around the hoop surface of the rock sample, and the free end of the first inelastic flexible wire 22 being fixedly connected with the detection end of a first displacement sensor 23.

[0043] Specifically, the axial deformation measuring assembly 3 comprises a second inelastic flexible wire 32 arranged vertically, one end of the second inelastic flexible wire 32 being fixed on the axial pressure head 11 in the triaxial chamber 1 through a second pre-tightening winding device 31, and the other end of the second inelastic flexible wire 32 being fixed on the detection end of a second displacement sensor 33.

[0044] The circumferential deformation measuring assembly 2 and the axial deformation measuring assembly 3 replace the rigid measuring rod (for example, the sensor support in the rock sample deformation measuring device and equipment with publication number CN212692781U) of the traditional LVDT by the inelastic flexible wire, not only reduces the volume, so that the triaxial chamber 1 can be more miniaturized, but also eliminates the measurement error caused by material thermal expansion, and at the same time, meets the needs of measuring the circumferential deformation and the axial deformation of the rock sample. The bottom of the axial pressure head 11 and the bottom of the rock sample are respectively provided with an upper pad 12 and a lower pad 13, and the circumferential wall of the upper pad 12 is fixedly connected with the second pre-tightening reel 31 through positioning bolts 121. The first pre-tightening reel 21 and the second pre-tightening reel 31 can be a reel with contraction force or a low-friction pulley.

[0045] In the embodiment, the first displacement sensor 23 and the second displacement sensor 33 are respectively used to detect the displacement of the first inelastic flexible wire 22 and the second inelastic flexible wire 32, and the first displacement sensor 23 and the second displacement sensor 33 are arranged in the base of the triaxial chamber 1. By embedding the first displacement sensor 23 and the second displacement sensor 33 in the base of the triaxial chamber 1, the internal space of the triaxial chamber 1 is not occupied, so that the triaxial chamber 1 can be designed to be more compact, the amount of confining oil medium is reduced, the temperature rising and falling time is shortened, and the triaxial chamber 1 is avoided to be directly exposed to the high-temperature and high-pressure environment, so that the reliability of the triaxial chamber 1 in the high-temperature environment is significantly improved. At the same time, the mechanical transmission scheme of the displacement sensor combined with the inelastic flexible wire is used to replace the imported special sensor, and the cost is reduced.

[0046] The first displacement sensor 23 and the second displacement sensor 33 are the same in structure, and can refer to Figure 2 and Figure 3 , which both include a shell 4, a threaded structure 401 is arranged on the outer wall of the shell 4, the threaded structure 401 is threadedly connected with a sink groove in the base of the triaxial chamber 1, and a sealing ring is arranged on the top of the threaded structure 401.

[0047] A cavity 41 is arranged in the shell 4, a third slip ring sealing ring 45 is arranged in the middle of the inner wall of the cavity 41, a floating disc column 42 is slidingly sealed in the third slip ring sealing ring 45, and the upper end face and the lower end face of the floating disc column 42 are fixed with the top end and the bottom end of the cavity 41 through upper and lower balance spring assemblies.

[0048] The top end and the bottom end of the cavity 41 are respectively communicated with the first channel 411 and the second channel 412 in the shell 4, and the first sliding ring seal 451 and the second sliding ring seal 452 are respectively arranged in the first channel 411 and the second channel 412; the middle parts of the first sliding ring seal 451 and the second sliding ring seal 452 are respectively slidingly connected with the upper connecting column 421 and the lower connecting column 422 of the floating disc column 42, the upper connecting column 421 is fixedly connected with the first inelastic flexible wire 22 or the second inelastic flexible wire 32, the lower connecting column 422 is fixedly connected with the iron core 43, and the second channel 412 is provided with the coil 44 for detecting the moving signal of the iron core 43. The inner wall of the second channel 412 is provided with the ceramic lining 4121, and the connecting position of the lower connecting column 422 and the iron core 43 is provided with the heat insulation sheet 431. The arrangement of the heat insulation sheet 431 and the ceramic lining 4121 reduces the influence of metal heat transfer on the core part of the sensor.

[0049] The cavity 41 is provided with the surrounding pressure oil channel 413 at the wall body between the second sliding ring seal 452 and the third sliding ring seal 45, and the triaxial chamber 1 is communicated with the surrounding pressure oil channel 413 and the first sliding ring seal 451 at the upper part of the first channel 411. In order to ensure that the force area of the upper end surface and the lower end surface of the floating disc column 42 is consistent, the top surface area of the upper connecting column 421 is equal to the annular bottom surface area of the floating disc column 42, that is, the upper end surface pressure F4 of the floating disc column 42 is equal to the lower end surface pressure F5 of the floating disc column 42, so that the tilt jam caused by the pressure difference is avoided, and the sensitivity of the sensor is improved.

[0050] In the embodiment, the floating disc column 42 includes an initial state and a moving state; when the floating disc column 42 is in the initial state, the floating disc column 42 is located in the middle part of the cavity 41, and the sum of the pre-tightening force F1 of the first pre-tightening winder 21 or the first pre-tightening winder 21 and the tension F2 of the upper balance spring assembly is equal to the sum of the sinking force G of the floating disc column 42 and the tension F3 of the lower balance spring assembly, and the sinking force G includes all the gravity of the floating disc column 42 and the connecting structure on the floating disc column 42. In this way, the floating disc column 42 is always in a dynamic balance state and only responds to the displacement change of the wire. In order to realize the balance, the rigidity of the lower balance spring assembly is greater than the rigidity of the upper balance spring assembly.

[0051] As a further scheme of the embodiment, in view of the inclination of the first inelastic flexible wire 22 and the second inelastic flexible wire 32 during the deformation of the rock sample, which affects the detection accuracy of the first displacement sensor 23 and the second displacement sensor 33, a planar sliding table is arranged on the top surface of the upper connecting column 421, and a sliding block for sliding on the planar surface is arranged on the planar sliding table, and the sliding block is fixedly connected with the first inelastic flexible wire 22 or the second inelastic flexible wire 32. The connection of the first inelastic flexible wire 22 or the second inelastic flexible wire 32 can be moved through the sliding block on the planar sliding table, so that the first inelastic flexible wire 22 and the second inelastic flexible wire 32 can both remain vertical under the constant pre-tightening force of the first pre-tightening reel 21 and the second pre-tightening reel 31, thereby improving the measurement accuracy of the hoop deformation and the measurement accuracy of the axial deformation. Preferably, in order to adapt to the narrow installation surface of the upper connecting column 421, the planar sliding table can be a horizontal moving cross bar arranged on the upper connecting column 421, and the sliding block is a linear bearing directly sleeved on the cross bar, and the linear bearing is fixedly connected with the first inelastic flexible wire 22 or the second inelastic flexible wire 32. The cooperation of the linear bearing and the cross bar realizes the effect of the XY two-dimensional sliding block, and reduces the space, and at the same time the linear bearing itself can rotate on the cross bar, which can ensure that the connection end of the first inelastic flexible wire 22 or the second inelastic flexible wire 32 is always upward.

[0052] As a further scheme of the embodiment, the HPHT triaxial test device further comprises a carrying mechanism for moving the triaxial chamber 1. The carrying mechanism can comprise a carrying conveyor belt and a carrying robot. Traditional high-temperature experiments require 3-4 hours in both the heating and cooling steps, resulting in more than 10 hours for a high-temperature experiment, and at most one high-temperature experiment per day. The size of the triaxial chamber 1 of the present scheme can be significantly reduced, the amount of confining pressure oil medium can be reduced, and the heating and cooling time can be shortened, so that the detachable triaxial chamber 1 cooperates with the carrying mechanism, and multiple triaxial chambers 1 can be loaded and cooled in turn, thereby increasing the number of experiments per day from one to four to six.

[0053] In summary, the present embodiment provides a measurement method of a limited-space high-temperature high-pressure cylindrical sample deformation measurement device, comprising the following steps:

[0054] S1, the rock sample in each triaxial chamber 1, and the upper pad 12 and the lower pad 13 respectively located at the top and the bottom of the rock sample are wrapped with a heat shrinkable film 14, and the hoop deformation measurement assembly 2 and the axial deformation measurement assembly 3 are installed;

[0055] S2, oiling and heating each triaxial chamber 1, and after reaching the target temperature, moving each triaxial chamber 1 to the loading table of the HPHT triaxial test equipment in turn by the carrying mechanism, and loading each triaxial chamber 1 with confining pressure and axial pressure in turn by the loading table, and after loading is completed, carrying each loaded triaxial chamber 1 to the cooling area in turn by the carrying mechanism;

[0056] S3, collecting the hoop deformation and axial deformation of each rock sample by the hoop deformation measurement assembly 2 and the axial deformation measurement assembly 3 in each triaxial chamber 1.

[0057] Specifically, the principle of the hoop deformation measurement assembly 2 and the axial deformation measurement assembly 3 in use is as follows:

[0058] Since the length of the inelastic flexible wire remains constant, when the rock sample produces hoop expansion, the upper connecting rod moves upward, driving the iron core 43 to move, causing the induced voltage in the coil 44 to change, and after demodulation and amplification, an electrical signal corresponding linearly to the displacement can be output. Correspondingly, when the rock sample produces hoop shrinkage deformation, the tension F1 of the inelastic flexible wire decreases, and F3 must decrease to maintain force balance, the disc drives the iron core 43 to move downward, and the output signal can also reflect the shrinkage amount accordingly. Thus, the hoop strain of the sample can be obtained by dividing the displacement of the iron core 43 by the hoop circumference of the sample: upward movement of the iron core 43 corresponds to expansion deformation, and downward movement of the iron core 43 corresponds to shrinkage deformation. Similarly to the above principle, when the rock sample produces axial compression, the iron core 43 moves downward; when the rock sample produces axial elongation, the iron core 43 moves upward. At this time, the axial strain of the sample can be obtained by dividing the displacement of the iron core 43 by the height of the sample: upward movement of the iron core 43 corresponds to tensile deformation, and downward movement of the iron core 43 corresponds to compressive deformation.

[0059] Although the specific embodiments of the application are described in detail with reference to the accompanying drawings, it should not be understood as limiting the scope of protection of the present application. Various modifications and variations made by those skilled in the art within the scope described in the claims are still within the scope of protection of the present application.

Claims

1. A device for measuring the deformation of a cylindrical sample under high temperature and high pressure in a confined space, characterized in that, The application relates to a high-pressure and high-temperature (HPHT) triaxial experimental device, which comprises at least one detachable triaxial chamber (1), a rock sample arranged in each triaxial chamber (1), a ring-direction deformation measuring assembly (2) and an axial-direction deformation measuring assembly (3) arranged on the rock sample. The ring-direction deformation measuring assembly (2) comprises a first pre-tightening winding device (21) arranged on the ring surface of the rock sample, a first inelastic flexible wire (22) arranged around the ring surface of the rock sample in the first pre-tightening winding device (21), and a first displacement sensor (23) fixedly connected with the free end of the first inelastic flexible wire (22). The axial-direction deformation measuring assembly (3) comprises a second inelastic flexible wire (32) vertically arranged, one end of the second inelastic flexible wire (32) is fixed on an axial-direction pressing head (11) in the triaxial chamber (1) through a second pre-tightening winding device (31), and the other end of the second inelastic flexible wire (32) is fixed on the detection end of a second displacement sensor (33). The first displacement sensor (23) and the second displacement sensor (33) are respectively used for detecting the displacement of the first inelastic flexible wire (22) and the second inelastic flexible wire (32), and the first displacement sensor (23) and the second displacement sensor (33) are arranged in the base of the triaxial chamber (1). The first displacement sensor (23) and the second displacement sensor (33) are structurally identical, and each comprises an outer shell (4) provided with a cavity (41), a third sliding ring seal ring (45) arranged in the middle of the inner wall of the cavity (41), a floating disc column (42) slidingly sealed in the third sliding ring seal ring (45), and the upper end face and the lower end face of the floating disc column (42) are fixed to the top end and the bottom end of the cavity (41) through upper and lower balance spring assemblies. The top end and the bottom end of the cavity (41) are respectively communicated with a first channel (411) and a second channel (412) in the outer shell (4), the first channel (411) and the second channel (412) are respectively provided with first and second sliding ring seal rings (451) and (452), the middle parts of the first and second sliding ring seal rings (451) and (452) are respectively slidingly connected with the upper and lower connecting columns (421) and (422) of the floating disc column (42), the upper connecting column (421) is fixedly connected with the first inelastic flexible wire (22) or the second inelastic flexible wire (32), the lower connecting column (422) is fixedly connected with an iron core (43), and the second channel (412) is provided with a coil (44) for detecting the movement signal of the iron core (43). The cavity (41) is provided with an oil passage (413) at the wall between the second sliding ring seal (452) and the third sliding ring seal (45), and the triaxial chamber (1) is in communication with the oil passage (413) and the first sliding ring seal (451) at the upper part of the first passage (411).

2. The apparatus according to claim 1, wherein The top surface area of the upper connecting column (421) is equal to the annular bottom surface area of the floating disc column (42).

3. The apparatus according to claim 2, wherein The floating disc column (42) comprises an initial state and a moving state; when the floating disc column (42) is in the initial state, the floating disc column (42) is located in the middle of the cavity (41), and the sum of the pre-tightening force of the first pre-tightening reel (21) or the first pre-tightening reel (21) and the tension of the upper balance spring assembly is equal to the sum of the sinking force of the floating disc column (42) and the tension of the lower balance spring assembly.

4. The apparatus according to claim 2, wherein The inner wall of the second passage (412) is provided with a ceramic lining (4121), and the connecting position of the lower connecting column (422) and the iron core (43) is provided with a heat insulation sheet (431).

5. The apparatus for measuring deformation of a high-temperature high-pressure cylindrical sample in a limited space according to claim 2, wherein The outer wall of the shell (4) is provided with a threaded structure (401), and the threaded structure (401) is in threaded connection with a sink groove in the base of the triaxial chamber (1).

6. The apparatus according to claim 2, wherein The top surface of the upper connecting column (421) is provided with a planar sliding table, the planar sliding table is provided with a sliding block for sliding on the planar surface, and the sliding block is fixedly connected with the first inelastic flexible wire (22) or the second inelastic flexible wire (32).

7. The apparatus according to claim 1, wherein The bottom of the axial pressure head (11) and the bottom of the rock sample are respectively provided with an upper pad (12) and a lower pad (13), and the annular wall of the upper pad (12) is fixedly connected with the second pre-tightening reel (31) through positioning bolts (121).

8. The apparatus according to claim 1, wherein The HPHT triaxial experimental equipment further comprises a carrying mechanism for moving the triaxial chamber (1).

9. The measurement method of the limited space high temperature and high pressure cylinder sample deformation measuring apparatus according to any one of claims 1 to 8, characterized by, The method comprises the following steps: S1, the rock sample in each triaxial chamber (1), and the upper pad (12) and the lower pad (13) respectively located at the top and the bottom of the rock sample are wrapped with a heat shrinkable film (14) as a whole, and a circumferential deformation measuring assembly (2) and an axial deformation measuring assembly (3) are installed; S2, each triaxial chamber (1) is filled with oil and heated, and after reaching the target temperature, each triaxial chamber (1) is moved to the loading table of the HPHT triaxial experimental equipment in sequence through the carrying mechanism, and the loading table is used to load the confining pressure and the axial pressure on each triaxial chamber (1) in sequence, and after the loading is completed, each triaxial chamber (1) after the loading is completed is carried to the cooling area through the carrying mechanism; S3, the circumferential deformation and the axial deformation of each rock sample are collected through the circumferential deformation measuring assembly (2) and the axial deformation measuring assembly (3) in each triaxial chamber (1).

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