Rock mass hydraulic fracturing test device and method based on flexible hydraulic pillow stress monitoring

Abstract

The application discloses a kind of rock mass hydraulic fracturing test device and method based on flexible hydraulic pillow stress monitoring, comprising: the rock mass to be tested, is provided with the fracturing hole that penetrates normal direction on it;Hydraulic pillow, including flexible normal load loading hydraulic pillow, horizontal load loading hydraulic pillow and longitudinal load loading hydraulic pillow, through hole is arranged on normal load loading hydraulic pillow, water injection fracturing device, including high-pressure water pump, and the fracturing assembly of high-pressure water pump is connected by high-pressure pipeline, the fracturing assembly is set in the fracturing hole of the rock mass to be tested by through hole;Data acquisition system includes hydraulic pillow pressure sensor connected with hydraulic pillow, waterway pressure sensor being arranged on high-pressure pipeline and data acquisition terminal being electrically connected with hydraulic pressure sensor and waterway pressure sensor.The application can perfectly fit the surface of rock mass to realize flexible loading, the additional stress generated by sealing reinforcement measure is considered, and then the precision of triaxial loading is improved.

Description

Technical Field

[0001] This invention belongs to the technical field of rock mechanics testing, specifically relating to a rock mass hydraulic fracturing test device and method based on stress monitoring of a flexible hydraulic pillow. Background Technology

[0002] Hydraulic fracturing technology is an important tool in the fields of deep-earth resource reservoir stimulation and in-situ stress testing. Simulation of the physical processes of hydraulic fracturing is an approximate reproduction of fracture evolution and its hydraulic coupling during rock fracturing; simultaneously, physical simulation experiments are also a necessary method for evaluating the reliability of numerical simulation results. Because physical simulation has a stronger correlation with reality than numerical simulation, and is characterized by low cost and ease of operation, it plays a crucial role in hydraulic fracturing research. Therefore, a scientifically rigorous physical simulation test design is indispensable for exploring the fracturing mechanism of rock masses under hydraulic fracturing.

[0003] Currently, hydraulic fracturing equipment is developing towards multi-field coupling with more simulation conditions, a wider simulation range, and a larger simulation scale, and fracturing methods are gradually diversifying with engineering applications. However, the triaxial loading accuracy of fracturing equipment needs further improvement. In the process of hydraulic fracturing of rock masses, epoxy resin or sealing rings are often used to seal and reinforce the fracturing test section to prevent leakage of fracturing fluid. However, the additional stress generated by sealing or reinforcement is often ignored.

[0004] Application number CN120609660A discloses a test method for simulating rock hydraulic fracturing under true triaxial stress. By conducting hydraulic fracturing tests with different hydraulic pressurization sequences, a qualitative analysis of the evolution law of reservoir rock cracks under true triaxial stress is completed, so as to optimize the location layout of hydraulic fracturing wells and the sequence of hydraulic pressure application.

[0005] Application number CN120609684A discloses an experimental method for hydraulic fracturing of rocks under true triaxial stress. It proposes to apply pulsed circulating water pressure using a pressure bar. The advantage is that the frequency and magnitude of the water pressure application are more consistent with the actual working conditions at the bottom of the well in hydraulic fracturing engineering. Furthermore, by changing the impact speed of the pressure bar, the high and low water pressure exchange can be simulated without pausing the water pressure application, so as to better study the mechanism of pulsed circulating hydraulic fracturing.

[0006] Application number CN114294059A discloses a high-precision control method for hydraulic fracturing of hard rock formations. The method pre-determines the hard rock formations based on the borehole columnar section of geological exploration; and obtains the actual rock formation information of the target rock formation through borehole logging analysis, thereby adjusting the hydraulic fracturing process parameters to achieve high-precision control of the formations.

[0007] Patent CN219864999U provides a directional hydraulic fracturing device, which can perform directional hydraulic fracturing by having a slotting pipe on the outside of the injection section. It can conveniently and efficiently realize the integration of slotting and fracturing, enabling hydraulic fractures to be effectively directionally initiated and propagated.

[0008] Application number CN111691871A discloses a method for monitoring crack propagation in a hydraulically fracturing rock pretreatment test. The method evaluates the fracturing effect by comparing the longitudinal wave velocity of the rock mass before and after fracturing, and determines the propagation location of the hydraulic crack by inverting the microseismic signal data in the microseismic detector to locate the seismic source.

[0009] The above-mentioned hydraulic fracturing test studies on rock masses mainly focus on the pressurization method and the direction of hydraulic fracture propagation, while insufficient attention is paid to the influence of the test device itself on the fracturing test process. The applied triaxial stress state is usually obtained by the sensors of the loading device itself, rather than the true three-dimensional stress state of the rock mass. There is a lack of consideration for the additional stress generated by the rock mass sample under the action of sealing and reinforcement measures. The loading accuracy of the triaxial stress environment needs further consideration. Summary of the Invention

[0010] One objective of this invention is to address the shortcomings of existing technologies by providing a rock mass hydraulic fracturing test device based on stress monitoring of a flexible hydraulic pillow. This device uses a flexible loading device to apply triaxial loading to the rock mass. The loading device can perfectly conform to the surface of the rock mass to apply the loading, thereby improving the accuracy of the triaxial loading. Furthermore, it takes into account the additional stress generated by the sealing and reinforcement measures, thereby further improving the accuracy of the triaxial loading.

[0011] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0012] A rock mass hydraulic fracturing test device based on flexible hydraulic pillow stress monitoring includes:

[0013] The rock mass to be tested has fracturing holes that penetrate the normal direction.

[0014] The hydraulic pillow includes a flexible hydraulic pillow for normal load loading, a hydraulic pillow for horizontal load loading, and a hydraulic pillow for longitudinal load loading. The hydraulic pillows for normal load loading, horizontal load loading, and longitudinal load loading are fixed on the three corresponding surfaces of the rock mass to be tested. The hydraulic pillow for normal load loading is used to apply a normal load to the rock mass to be tested, the hydraulic pillow for horizontal load loading is used to apply a horizontal load to the rock mass to be tested, and the hydraulic pillow for longitudinal load loading is used to apply a longitudinal load to the rock mass to be tested. The hydraulic pillow for normal load loading has threaded through holes corresponding to the fracturing holes.

[0015] The water injection fracturing device includes a high-pressure water pump and a fracturing assembly connected to the high-pressure water pump via a high-pressure pipeline. The fracturing assembly is installed in the fracturing hole of the rock mass to be tested through a through hole. The high-pressure water pump injects fracturing fluid into the fracturing assembly through the high-pressure pipeline so that the rock mass to be tested is fractured.

[0016] The data acquisition system includes hydraulic pressure sensors connected to the hydraulic sleepers for normal load loading, horizontal load loading, and longitudinal load loading, respectively; a water pressure sensor installed on the high-pressure pipeline; and a data acquisition terminal electrically connected to the hydraulic pressure sensor and the water pressure sensor.

[0017] Furthermore, the fracturing assembly includes a central perforated tube disposed in the fracturing hole, an upper water-passing bolt and a lower water-passing bolt respectively connected to both ends of the central perforated tube. The upper water-passing bolt and the lower water-passing bolt each include a panel that presses against the hydraulic cushion under normal load and a bolt joint that is vertically disposed on the panel and passes through a through hole to connect with the central perforated tube. The panel has a water passage communicating with the central perforated tube, and the central perforated tube has multiple water outlet holes.

[0018] Furthermore, the inner diameter of the through hole is equivalent to the outer diameter of the bolt joint. An internal thread is provided in the through hole, and an external thread that mates with it is provided on the bolt joint. The two are connected by threads.

[0019] Furthermore, the outer diameter of the central perforated tube is comparable to the inner diameter of the fracturing hole.

[0020] Furthermore, flexible pads are installed between the hydraulic sleepers for normal load loading, horizontal load loading, and longitudinal load loading and the rock mass to be tested.

[0021] Furthermore, the hydraulic sleepers for normal load loading, horizontal load loading, and longitudinal load loading are all externally connected to a high-pressure water outlet hose, a high-pressure water inlet hose, and a high-pressure pressure monitoring hose. The high-pressure water inlet hose is also connected to a high-pressure water pump, the high-pressure pressure monitoring hose is connected to a pressure sensor of the hydraulic sleeper, and the high-pressure water outlet hose is used to unload the load.

[0022] Another object of the present invention is to provide a test method for a rock mass hydraulic fracturing test device based on the above-mentioned flexible hydraulic pillow stress monitoring, characterized by comprising the following steps:

[0023] Step 1: Drill a through-hole in the rock mass to be tested along the normal direction. Fix a hydraulic pillow for normal load on the normal surface of the rock mass to be tested. Fix a hydraulic pillow for horizontal load on the horizontal surface of the rock mass to be tested. Fix a hydraulic pillow for longitudinal load on the longitudinal surface of the rock mass to be tested. Install the fracturing assembly in the fracturing hole and connect the fracturing assembly to the high-pressure water pump through a high-pressure pipeline.

[0024] Step 2: Start the normal load loading hydraulic pillow to preload the rock mass under test in the normal direction, and then start the horizontal load loading hydraulic pillow and the longitudinal load loading hydraulic pillow to preload the rock mass under test.

[0025] Step 3: Simultaneously load the target load onto all six faces of the rock mass, maintain constant pressure, then start the high-pressure water pump to inject fracturing fluid into the fracturing assembly until the rock mass reaches the target failure state. After that, turn off the high-pressure water pump and use a data acquisition device to collect data from the hydraulic cushion pressure sensor and water circuit pressure sensor throughout the entire water injection fracturing process. Calculate the stress and strain of the rock mass based on the collected data.

[0026] Furthermore, in step 2, the preload in the normal, horizontal, and longitudinal directions does not exceed 1 MPa.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1) This invention uses a flexible hydraulic pillow to load the rock mass on six surfaces in three axes. This allows the flexible hydraulic pillow to adaptively adjust its contact with the rock mass surface during the pressurization process, thereby enabling the hydraulic pillow to apply uniform pressure to the rock mass surface during the loading process, thus improving the accuracy of triaxial loading.

[0029] 2) Current techniques for this test typically involve installing sealing and reinforcement devices (such as epoxy resin or bolt washers) at the orifice of the fracturing hole. This introduces additional anchoring stress into the fracturing specimen, which cannot be monitored. Furthermore, the impact of this additional stress is generally not considered when processing fracturing test data, thus affecting the accuracy of the stress state assessment of the specimen during the fracturing process. This invention, however, uses a hydraulic pillow to directly monitor the normal stress on the rock mass surface and employs a flexible hydraulic pillow as a stress transfer device. The advantages of the hydraulic pillow are mainly reflected in the following two aspects: First, by taking the anchoring force of the bolts into account, the accuracy of triaxial loading in the test is improved; second, the flexible loading method has the characteristic of adaptively conforming to the rock mass surface, which, compared to the traditional steel plate loading method, can effectively avoid uneven loading caused by non-ideal surface flatness. Attached Figure Description

[0030] Figure 1 A schematic diagram showing the results of the rock mass hydraulic fracturing test device according to an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of triaxial loading on the target rock mass for fracturing according to an embodiment of the present invention;

[0032] Figure 3 The following are three views of a hydraulic sleeper under normal load according to an embodiment of the present invention, wherein (a) is a front view, (b) is a top view, and (c) is a left view.

[0033] Figure 4 The following are structural views of the upper and lower water-passing bolts according to an embodiment of the present invention, wherein (a) is a top view and (b) is a front view. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0036] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0037] like Figure 1 As shown, this invention discloses a rock mass hydraulic fracturing test device based on stress monitoring using a flexible hydraulic pillow, including a rock mass 1 to be tested, a hydraulic pillow, a water injection fracturing device, and a data acquisition system. A through-hole is drilled along the normal center position of the rock mass 1 to be tested. The hydraulic pillow includes a flexible normal load loading hydraulic pillow 21, a horizontal load loading hydraulic pillow, and a longitudinal load loading hydraulic pillow 22. The normal load loading hydraulic pillow 21, the horizontal load loading hydraulic pillow, and the longitudinal load loading hydraulic pillow 22 are respectively fixed on the three corresponding surfaces of the rock mass 1 to be tested. Figure 2 As shown, the normal load loading hydraulic pillow 21 is used to apply a normal load to the rock mass under test, the horizontal load loading hydraulic pillow is used to apply a horizontal load to the rock mass under test, and the longitudinal load loading hydraulic pillow 22 is used to apply a longitudinal load to the rock mass under test. To ensure the loading conforms more closely to the rock surface, flexible lubricating gaskets are placed between the load loading hydraulic pillows in the three directions and the rock mass under test. Furthermore, to prevent fluid leakage during pressurization, sealing gaskets made of rubber are also placed between the load loading hydraulic pillows in the three directions and the rock mass under test.

[0038] To facilitate the installation of the water injection fracturing device, a through hole 210 corresponding to the fracturing hole is provided on the hydraulic pillow 21 under normal load, as shown in the figure. Figure 3 Each of the three load-bearing hydraulic pillows has three outlets on one side, which are respectively connected to a high-pressure water outlet hose, a high-pressure water inlet hose, and a high-pressure pressure monitoring hose.

[0039] The water injection fracturing device includes a high-pressure water pump 31 and a fracturing assembly connected to the high-pressure water pump 31 via a high-pressure pipeline. In this embodiment, the fracturing assembly includes a central perforated pipe 32 disposed in the fracturing hole, and an upper water-passing bolt 33 and a lower water-passing bolt 34 respectively connected to both ends of the central perforated pipe 32. See Figure 4 Both the upper water-passing bolt 33 and the lower water-passing bolt 34 include a panel 331 that presses against the hydraulic cushion 21 under normal load, and a bolt joint 332 vertically mounted on the panel 331 and connected to the central perforated pipe 32 through a through hole. The central perforated pipe 32 has multiple water outlet holes and is placed inside a specially designed fracturing sleeve 35. The specially designed fracturing sleeve is made of seamless steel pipe and has multiple holes. Both ends of the specially designed fracturing sleeve are externally connected to the bolt joint 332 as fracturing sections. The panel 331 has a water passage 333 communicating with the central perforated pipe 32. The water passage 333 is connected to a high-pressure water pump 31 via a high-pressure pipeline. During the test, the high-pressure water pump 31 injects high-pressure water into the central perforated pipe 32 through the high-pressure pipeline and the water passage 333, causing the rock mass under test to be fractured. To account for the anchoring force of the upper and lower water-passing bolts acting on the surface of the hydraulic cushion 21 under normal load, an internal thread is provided in the through hole, and a matching external thread is provided on the bolt joint 332, with the inner diameter of the through hole being approximately equal to the outer diameter of the bolt joint. To prevent fluid leakage during pressurization, a sealing ring is provided between the panel 331 and the hydraulic cushion 21 under normal load.

[0040] The data acquisition system includes hydraulic pressure sensors 41 connected to the hydraulic cushions 21 (normal load loading), 21 (horizontal load loading), and 22 (longitudinal load loading), water pressure sensors 42 mounted on the high-pressure pipeline, and a data acquisition terminal 43 electrically connected to the hydraulic pressure sensors 41 and 42. The hydraulic pressure sensors 41 are connected to a high-pressure monitoring hose and collect data on the pressure of the hydraulic cushions under load in all three directions during fracturing of the rock mass 1, obtaining the true triaxial stress state experienced by the rock mass during fracturing. The water pressure sensors 42 are mounted on the high-pressure pipeline and are used to collect the pressure within the fracturing hole during water-induced fracturing.

[0041] The method for conducting tests using the aforementioned rock mass hydraulic fracturing test device based on flexible hydraulic pillow stress monitoring includes the following steps:

[0042] Step 1, Sample preparation stage: The rock block is processed into a standard cubic rock mass, and a through-hole is drilled in the rock mass 1 according to the test target size, wherein the diameter of the through-hole matches the outer diameter of the central perforated tube 32;

[0043] Step 2, Fracturing Device Assembly Stage: The installation sequence from bottom to top is as follows: lower water-passing bolt 34, bolt gasket, lower normal load-loading hydraulic pillow 21, lower sealing gasket, central perforated pipe 32, fracturing casing 35, rock mass 1, horizontal load-loading hydraulic pillow (2 pieces), longitudinal load-loading device 22 (2 pieces), upper sealing gasket, upper normal load-loading hydraulic pillow 21, bolt gasket, upper water-passing bolt 33. Before installation, all hydraulic pillows are filled with water and sealed. After installation, pressure sensors 41 are connected to the hydraulic pillows via high-pressure monitoring hoses. Hydraulic pillow pressure sensors 41 and water circuit pressure sensors 42 are connected to data acquisition terminals 43 for real-time data collection, with a data acquisition frequency of no less than 10Hz.

[0044] Step 3, Sample Installation Stage: First, the rock mass is tested. Preloading is performed on the two surfaces in the direction of normal by connecting a high-pressure water inlet hose to a high-pressure water pump, which then injects water into the hydraulic cylinder until the preset pressure value is reached; afterwards, the horizontal direction is preloaded. With longitudinal Symmetrical preloading is performed in two directions (4 faces), using the same method as in the normal direction, while avoiding eccentric loading, and the preloading pressure does not exceed 1 MPa;

[0045] Step 4: After preloading, the hydraulic pillows in three directions are used to slowly and symmetrically load the six faces of rock mass 1 to the target load. After the load curve stabilizes, the loading is stopped and the pressure on the six faces remains unchanged.

[0046] Step 5: Open all hydraulic pressure sensors 41, water pressure sensors 42 and data acquisition terminal 43 to collect data, and turn on the high-pressure water pump. The high-pressure water pump injects high-pressure water into the fracturing hole through the water flow channel 333. After pressurizing the fracturing hole until the rock mass reaches the target failure state, turn off the high-pressure water pump.

[0047] Step 6: After the fracturing test is completed, the pressure on the six surfaces is slowly, symmetrically, and synchronously reduced to zero to avoid differential stress damage to the rock mass or affecting the fracture state caused by excessively rapid or asynchronous unloading; calculations are performed based on the collected data. , , The stress-strain condition was analyzed and fracturing curves were plotted. Based on the principle of force balance of the system, the force relationship of the rock mass sample can be calculated according to the following formula:

[0048] (1)

[0049] (2)

[0050] (3)

[0051] In the formula, σv σ is the normal stress acting on the rock mass. H / σ h These correspond to the maximum and minimum horizontal stresses acting on the rock mass, T, respectively. f For the preload of the center-split pipe thread, T c The preload force of the sleeve thread, together with the preload force of the center perforated pipe thread, acts on the water-passing bolt; P v / P H / P h These represent the internal pressure of the three-way hydraulic pillow, F V / F H / F h The three-way hydraulic sleeper is subjected to external loads, S V / S H / S h These represent the actual contact area between the three-dimensional hydraulic sleeper and the rock mass, K. V / K H / K h These are the pressure calibration coefficients of the three-dimensional hydraulic pillow. Due to the end effect caused by the shape of the hydraulic pillow, there is a certain proportional relationship between the internal pressure of the hydraulic pillow and the actual pressure acting on the rock surface. The proportional coefficient of each hydraulic pillow needs to be calibrated before the experiment.

[0052] Step 7: End of test: After unloading, remove the rock mass, describe the morphology of the hydraulic fracturing fractures, and the test is complete.

[0053] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. A rock mass hydraulic fracturing test device based on stress monitoring of a flexible hydraulic pillow, characterized in that, include: The rock mass to be tested has fracturing holes that penetrate the normal direction. The hydraulic pillow includes a flexible hydraulic pillow for normal load loading, a hydraulic pillow for horizontal load loading, and a hydraulic pillow for longitudinal load loading. The hydraulic pillows for normal load loading, horizontal load loading, and longitudinal load loading are fixed on the three corresponding surfaces of the rock mass to be tested. The hydraulic pillow for normal load loading is used to apply a normal load to the rock mass to be tested, the hydraulic pillow for horizontal load loading is used to apply a horizontal load to the rock mass to be tested, and the hydraulic pillow for longitudinal load loading is used to apply a longitudinal load to the rock mass to be tested. The hydraulic pillow for normal load loading has through holes corresponding to the fracturing holes. The water injection fracturing device includes a high-pressure water pump and a fracturing assembly connected to the high-pressure water pump via a high-pressure pipeline. The fracturing assembly is installed in the fracturing hole of the rock mass to be tested through a through hole. The high-pressure water pump injects fracturing fluid into the fracturing assembly through the high-pressure pipeline so that the rock mass to be tested is fractured. The data acquisition system includes hydraulic pressure sensors connected to the hydraulic sleepers for normal load loading, horizontal load loading, and longitudinal load loading, respectively; a water pressure sensor installed on the high-pressure pipeline; and a data acquisition terminal electrically connected to the hydraulic pressure sensor and the water pressure sensor.

2. The rock mass hydraulic fracturing test device based on flexible hydraulic pillow stress monitoring according to claim 1, characterized in that, The fracturing assembly includes a central perforated tube disposed in the fracturing hole, an upper water-passing bolt and a lower water-passing bolt respectively connected to both ends of the central perforated tube. The upper water-passing bolt and the lower water-passing bolt each include a panel that presses against the hydraulic cushion under normal load and a bolt joint that is vertically disposed on the panel and passes through a through hole to connect with the central perforated tube. The panel has a water flow channel communicating with the central perforated tube, and the central perforated tube has multiple water outlet holes.

3. The rock mass hydraulic fracturing test device based on flexible hydraulic pillow stress monitoring according to claim 1, characterized in that, The inner diameter of the through hole is equivalent to the outer diameter of the bolt joint. An internal thread is set in the through hole, and an external thread that matches it is set on the bolt joint. The two are connected by threads.

4. The rock mass hydraulic fracturing test device based on flexible hydraulic pillow stress monitoring according to claim 1, characterized in that, The outer diameter of the central perforated tube is approximately equal to the inner diameter of the fracturing hole.

5. The rock mass hydraulic fracturing test device based on flexible hydraulic pillow stress monitoring according to claim 1, characterized in that, Flexible pads are installed between the hydraulic sleepers for normal load loading, horizontal load loading, and longitudinal load loading and the rock mass to be tested.

6. The rock mass hydraulic fracturing test device based on flexible hydraulic pillow stress monitoring according to claim 1, characterized in that, The hydraulic sleepers for normal load loading, horizontal load loading, and longitudinal load loading are all externally connected to a high-pressure water outlet hose, a high-pressure water inlet hose, and a high-pressure pressure monitoring hose. The high-pressure water inlet hose is also connected to a high-pressure water pump, and the high-pressure pressure monitoring hose is connected to a pressure sensor of the hydraulic sleeper. The high-pressure water outlet hose is used to unload the load.

7. A test method using the rock mass hydraulic fracturing test device based on flexible hydraulic pillow stress monitoring as described in any one of claims 1-7, characterized in that, The steps include the following: Step 1: Drill a through-hole in the rock mass to be tested along the normal direction. Fix a hydraulic pillow for normal load on the normal surface of the rock mass to be tested. Fix a hydraulic pillow for horizontal load on the horizontal surface of the rock mass to be tested. Fix a hydraulic pillow for longitudinal load on the longitudinal surface of the rock mass to be tested. Install the fracturing assembly in the fracturing hole and connect the fracturing assembly to the high-pressure water pump through a high-pressure pipeline. Step 2: Start the normal load loading hydraulic pillow to preload the rock mass under test in the normal direction, and then start the horizontal load loading hydraulic pillow and the longitudinal load loading hydraulic pillow to preload the rock mass under test. Step 3: Simultaneously load the target load onto all six faces of the rock mass, maintain constant pressure, then start the high-pressure water pump to inject fracturing fluid into the fracturing assembly until the rock mass reaches the target failure state. After that, turn off the high-pressure water pump and use a data acquisition device to collect data from the hydraulic cushion pressure sensor and water circuit pressure sensor throughout the entire water injection fracturing process. Calculate the stress and strain of the rock mass based on the collected data.

8. The test method for rock mass hydraulic fracturing test device based on flexible hydraulic pillow stress monitoring according to claim 1, characterized in that, In step 2, the preload in the normal, horizontal and longitudinal directions shall not exceed 1 MPa.

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