Thermal-fluid-solid coupling partition loading test device and method

Abstract

The invention discloses a heat-fluid-solid coupling partition loading test device and method, and relates to the technical field of deep mines and engineering. The device comprises an outer shell with the front portion and the rear portion closed and an inner shell placed in the outer shell, a three-way pressurizing device and a counter-force frame are arranged between the outer shell and the inner shell, a coal rock test piece is placed in the inner shell, a plurality of multifunctional measuring pipes are arranged in the inner shell, an inflation hole is formed in the outer shell, a groove is formed in the counter-force frame, and a sensor hole is formed in the groove; the test method comprises the following steps: loading a coal rock test piece, heating the multifunctional measuring tube in a partitioned manner to simulate a ground temperature gradient, inflating step by step to construct partitioned gas pressure, and applying stress to the three-way oil cylinder to simulate field stress distribution, so as to realize coupled partitioned loading of ground temperature, gas and stress. According to the invention, the complex occurrence environment of the deep non-uniform stratum can be truly restored, the problem that the existing device cannot simulate the zoning temperature and pressure stress characteristics is solved, and a scientific and reliable test platform is provided for deep coal mine dynamic disaster mechanism research.

Description

Technical Field

[0001] This invention relates to the field of deep mining and deep engineering technology, specifically to a thermo-fluid-solid coupled zone loading test device and method. Background Technology

[0002] With the depletion of shallow coal resources, the shift of mining focus to deeper strata has become an inevitable trend. Deep strata have undergone multiple phases of tectonic movement and sedimentary evolution throughout their long geological history, resulting in extremely complex and heterogeneous structures. At the microscopic level, differences in mineral composition, cementation degree, and microfracture distribution determine the basic mechanical properties of coal and rock. At the macroscopic level, geological structures such as faults and joints form anisotropic composite structures with varying mechanical properties. This multi-scale heterogeneity is particularly pronounced in the deep "four high" environment (high ground stress, high ground temperature, high osmotic pressure, and high gas pressure), leading to extremely uneven stress distribution and a strong size effect in the mechanical behavior of coal and rock masses. Non-uniformity poses a serious threat to the safety of deep coal mining: mining-induced stresses concentrate dramatically around weak structural planes, easily inducing dynamic disasters such as rock bursts and rockbursts; non-uniform fracture networks provide uneven transport channels for gas and groundwater, significantly increasing the risk of coal and gas outbursts and water inrushes; traditional support designs based on homogeneous assumptions often fail in non-uniform surrounding rock, leading to uncontrolled roadway deformation and soaring support costs. Therefore, deep non-uniform geological structures severely impact mining safety.

[0003] Physical simulation experiments are widely used in the study of coal mine dynamic disaster mechanisms due to their advantages such as good repeatability, adjustable and controllable factors, low cost, and short cycle. Current dynamic disaster simulation devices mostly simulate homogeneous strata, which differ significantly from the actual conditions of coal and rock strata structures, stress concentrations, zoned fracturing, zoned gas-liquid characteristics, and geothermal gradient distribution in deep coal mines. Therefore, they cannot meet the needs of dynamic disaster prevention and control in deep coal mines. Thus, there is an urgent need to propose a thermo-fluid-solid coupled zoned loading test device and method to realistically simulate the complex environment of deep strata, providing a scientific and reliable testing platform for conducting physical simulation experiments on coal mine dynamic disasters. Summary of the Invention

[0004] The purpose of this invention is to provide a thermal-fluid-structure interaction zoned loading test device and method to solve the problems existing in the prior art.

[0005] The technical solution adopted in this invention is: a thermo-fluid-structure interaction zoned loading test device, comprising:

[0006] outer shell;

[0007] The inner shell is placed inside the outer shell and is used to hold the coal and rock specimens;

[0008] The three-dimensional pressurizing device is respectively placed on the top, left side and front end of the inner shell, and is used to apply three-dimensional pressure to the coal and rock specimen. The rear end of each pressurizing device is fixed to the inner wall of the outer shell. The three-dimensional pressurizing device includes a combined hydraulic cylinder and a distributed pressure plate. The combined hydraulic cylinder is fixedly connected to the distributed pressure plate through a piston rod.

[0009] The reaction frame is located inside the outer shell, below and on the right side of the inner shell. Its front end is fixedly connected to the inner shell, and its rear end is fixedly connected to the inner wall of the outer shell (1). A slot is opened inside the reaction frame, and a sensor hole communicating with the outer shell is arranged in the slot.

[0010] Multiple multifunctional measuring tubes are set up and evenly arranged inside the coal and rock specimen along the length of the specimen. The tubes are circumferentially vented and have resistance wires wound around them.

[0011] As a further improvement of the present invention, the combined hydraulic cylinder is composed of multiple individual hydraulic cylinders, and the distributed pressure plate is composed of multiple individual pressure plates. The individual hydraulic cylinders are connected to the individual pressure plates through piston rods.

[0012] As a further improvement of the present invention, the outer shell is cylindrical, closed at one end and provided with a detachable end cap at the other end; the bottom is supported by a base; the inner shell is cuboid.

[0013] As a further improvement of the present invention, an air inlet is provided on the outer shell.

[0014] Secondly, the present invention also proposes a thermo-fluid-structure interaction (TFI) partitioned loading test method, which employs the aforementioned thermo-fluid-structure interaction (FFI) partitioned loading test apparatus and includes the following steps:

[0015] Step S1: For mines where dynamic disaster simulation is to be carried out, conduct on-site testing of the triaxial stress, ground temperature, gas pressure, and physical and mechanical parameters of the coal seam, roof, and floor; formulate an experimental plan based on the actual on-site parameters and similarity theory, and prefabricate coal and rock specimens;

[0016] Step S2: Open the inner shell, insert the coal and rock specimen, and install the multi-functional measuring tube and sensor;

[0017] Step S3: Start the triaxial pressurization device to apply triaxial stress to the coal and rock specimens to simulate the stress distribution pattern of the three zones in the field;

[0018] Step S4: Open the gas filling switches of the four multi-functional measuring tubes. Select the minimum gas pressure according to the formation gas pressure distribution to simultaneously fill and adsorb different areas of the coal and rock specimen until the adsorption reaches the minimum gas pressure. Then close all the gas filling switches. Open the gas filling port to fill the outer shell with gas, maintaining the gas pressure balance between the inner and outer shells and the coal and rock specimen.

[0019] Step S5: Turn on the heating switch of the multi-functional measuring tube and heat different areas of the coal and rock specimen according to the formation temperature distribution to show the different temperature distributions in different areas;

[0020] Step S6: When the coal seam stress, temperature and field parameter values ​​are similar, open the air filling switch of three of the multi-functional measuring tubes to perform air filling and adsorption, and keep the air pressure at the air inlet stable according to the gas pressure distribution of the formation.

[0021] Step S7: Conduct coal mine dynamic disaster simulation tests as needed.

[0022] Compared with the prior art, the present invention has the following technical advantages:

[0023] This invention achieves comprehensive deep stratum coupled zonal loading by considering factors such as ground temperature, gas pressure, and triaxial stress, realistically simulating the complex environment of deep strata. Regarding ground temperature, different temperature gradients can be achieved through heating with four multifunctional measuring tubes. For gas pressure, zonal gas distribution is achieved by first balancing the gas pressure to minimum and then simultaneously opening other air intake switches. Regarding stress, stress concentration can be simulated through distributed hydraulic cylinder grouping control. Furthermore, the coupling of ground temperature, gas pressure, and stress provides a scientifically sound and universally applicable experimental platform for simulating deep dynamic disasters. Attached Figure Description

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] Figure 1 This is a cross-sectional view of the thermo-fluid-structure interaction zoned loading test apparatus and method of the present invention;

[0026] Figure 2 This is a cross-sectional view of the thermo-fluid-structure interaction zoned loading test apparatus and method of the present invention;

[0027] In the figure, 1-outer shell; 2-inner shell; 3-base; 4-coal and rock specimen; 5, 8, 14-combined hydraulic cylinder; 6, 9, 15-distributed pressure plate; 7, 10-reaction frame; 11-air inlet; 12-multifunctional measuring tube; 13-sensor hole. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0029] like Figure 1 and Figure 2 As shown, a thermo-fluid-structure interaction (TFS) zonal loading test device of the present invention includes an outer shell 1, an inner shell 2, a pressurizing device, reaction frames 7 and 10, and a multi-functional measuring tube 12. Specifically, the outer shell 1 is closed at one end and has an openable end cap at the other end. The bottom of the outer shell 1 is supported by a base 3. The outer shell 1 has a diameter of 2 meters and a length of 4 meters. An air inlet 11 is provided on the outer shell 1. The inner shell 2 is placed inside the outer shell 1 and is used to place the coal and rock specimen 4. The inner shell 2 is a cuboid with a side length of 1 meter. The inner shell 2 and the outer shell 1 are made of thin steel plates welded together.

[0030] The pressurizing device is located between the outer shell 1 and the inner shell 2, and is used to apply pressure to the coal and rock specimen 4. Three pressurizing devices are respectively placed on the top, left side, and front end of the inner shell 2, providing triaxial (X, Y, and Z) stress to the coal and rock specimen 4. The pressurizing device includes distributed pressure plates 6, 9, and 15 and combined hydraulic cylinders 5, 8, and 14. Specifically, the combined hydraulic cylinders 5, 8, and 14 are composed of multiple individual hydraulic cylinders. Each individual hydraulic cylinder is powered by a hydraulic system, and each individual hydraulic cylinder is equipped with a solenoid valve. The solenoid valve is controlled by a PLC to control the movement of the individual hydraulic cylinder. The distributed pressure plates 6, 9, and 15 are composed of multiple upper pressure plates, and the individual hydraulic cylinders are connected to the pressure plates via piston rods. During pressurization, the PLC drives all the individual cylinders in the three combined cylinders 5, 8, and 14 to operate simultaneously, applying a uniform pressure across the entire cross-section of the coal and rock specimen 4, or driving some of the individual cylinders on the three surfaces to operate, simulating the application of unbalanced pressure to each surface of the coal and rock specimen 4, thereby more realistically simulating the stress distribution of the coal seam on site.

[0031] The reaction frames 7 and 10 are located inside the outer shell 1, below and on the right side of the inner shell 2, and are used to provide reverse support for the coal and rock specimen 4 when the pressurizing device applies pressure. A slot is cut inside the reaction frames 7 and 10, and sensor holes 13 communicating with the outer shell 1 are arranged in the slot.

[0032] Four multifunctional measuring tubes 12 are arranged inside the coal and rock specimen 4. Specifically, four holes are drilled evenly along the centerline of the bottom surface of the coal and rock specimen 4, and then the four multifunctional measuring tubes 12 are embedded in them. The multifunctional measuring tubes 12 have vent holes evenly distributed along their length and circumference for filling the coal and rock specimen 4 with methane gas, and resistance wires are wound around the tubes for heating the coal and rock specimen 4.

[0033] Specifically, the four multi-functional measuring tubes 12 divide the coal and rock specimen 4 into four equal regions along its length, such as... Figure 2As shown, when filling the four regions with gas, gas at the same pressure can be filled at the same time, or gas at different pressures can be filled to reflect the regional distribution of different gas pressures in the coal seam on site. This can better approximate the actual situation during simulation, thereby obtaining more realistic and accurate test data.

[0034] This invention also proposes a thermo-fluid-structure interaction (TFI) partitioned loading test method, which uses the aforementioned TFI partitioned loading test device. This method includes the following steps:

[0035] Step S1: For mines where dynamic disaster simulation is to be conducted, conduct on-site testing of the triaxial stress, ground temperature, gas pressure, and physical and mechanical parameters of the coal seam, roof, and floor. Based on the actual on-site parameters and similarity theory, formulate an experimental plan and prefabricate coal and rock specimens 4. Specifically, similarity theory is a doctrine that studies the principles of similar phenomena in nature and engineering, mainly exploring the relationship between commonalities and individual characteristics of phenomena, as well as the similarity correlation between models and prototypes.

[0036] Step S2: Open the inner shell 2, insert the coal and rock specimen 4, and install the multi-functional measuring tube 12 and sensor;

[0037] Step S3: Start the triaxial pressure device to apply triaxial stress to the coal and rock specimen 4 to simulate the stress distribution law of the three zones in the field.

[0038] Step S4: Open the gas filling switch of the multi-functional measuring tube 12, select the minimum gas pressure according to the formation gas pressure distribution, and simultaneously fill and adsorb different areas of the coal and rock specimen 4 until the adsorption is balanced to the minimum gas pressure, then close the switch; then open the gas filling hole 11 and fill the outer shell 1 with gas to maintain the gas pressure balance between the inner and outer shells and the coal and rock specimen 4.

[0039] Step S5: Turn on the heating switch of the multi-functional measuring tube 12, and heat different areas of the coal and rock specimen 4 according to the formation temperature distribution, and keep it constant.

[0040] Step S6: When the coal seam stress, temperature and field parameter values ​​are similar, open the gas filling switch of the multi-functional measuring tube 12 corresponding to the three areas other than the minimum gas pressure area, and keep the gas pressure at the inlet stable according to the gas pressure distribution of the formation.

[0041] Step S7: Conduct coal mine dynamic disaster simulation tests as needed.

[0042] The experimental method of this invention achieves coupled zonal loading of ground temperature, gas pressure, and triaxial stress through a step-by-step, orderly operation process: First, the multi-functional measuring tube 12 is used to heat and maintain a constant temperature zone according to the formation temperature distribution, accurately simulating the ground temperature gradient; then, through a step-by-step inflation method of "first absorbing and balancing to the minimum gas pressure, then filling the outer cavity with the maximum gas pressure, and finally opening the inflation switch of a specific area," a gas pressure zonal distribution that conforms to the actual field conditions is constructed; finally, the combined hydraulic cylinder is activated to apply stress, further matching the field stress state. This method couples ground temperature, gas, and stress, realistically reproducing the complex environment of deep strata, effectively solving the problem that traditional methods cannot simulate the zonal temperature, pressure, and stress characteristics. It can provide a field-fitting experimental scenario for the study of the dynamic disaster mechanism in deep coal mines, help clarify the disaster evolution law, and provide scientific data support for the research and development of disaster prevention and control technologies.

[0043] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Various changes that can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention are within the protection scope of the claims of the present invention.

Claims

1. A thermo-fluid-structure interaction zoned loading test device, characterized in that, include: Outer shell (1); The inner shell (2) is placed inside the outer shell (1) and is used to place the coal and rock specimen (4); The three-dimensional pressurization device is placed on the top, left side and front end of the inner shell (2) respectively, and is used to apply three-dimensional pressure to the coal and rock specimen (4). The rear end of each pressurization device is fixed to the inner wall of the outer shell (1). The three-dimensional pressurization device includes a combination cylinder (5, 8, 14) and a distributed pressure plate (6, 9, 15). The combination cylinder (5, 8, 14) is fixedly connected to the distributed pressure plate (6, 9, 15) through a piston rod. The reaction frame (7, 10) is located inside the outer shell (1), below and on the right side of the inner shell (2). Its front end is fixedly connected to the inner shell (2), and its rear end is fixedly connected to the inner wall of the outer shell (1). A slot is opened inside the reaction frame (7, 10), and a sensor hole (13) communicating with the outer shell (1) is arranged in the slot. Multiple multifunctional measuring tubes (12) are set up and are evenly arranged in the coal and rock specimen (4) along the length direction. The multifunctional measuring tube (12) has air holes evenly distributed around its circumference and a resistance wire is wound around its body.

2. The thermo-fluid-structure interaction zoned loading test device according to claim 1, characterized in that, The combined hydraulic cylinders (5, 8, 14) are all composed of multiple individual hydraulic cylinders, and the distributed pressure plates (6, 9, 15) are all composed of multiple individual pressure plates. The individual hydraulic cylinders are connected to the individual pressure plates through piston rods.

3. The thermo-fluid-structure interaction zoned loading test apparatus according to claim 1, characterized in that, The outer shell (1) is cylindrical, closed at one end and provided with a detachable end cap at the other end; the bottom is supported by a base (3); the inner shell (2) is cuboid.

4. The thermo-fluid-structure interaction zoned loading test apparatus according to claim 1, characterized in that, An air inlet (11) is provided on the outer shell (1).

5. A method for a thermo-fluid-structure interaction (TFI) partitioned loading test, employing the TFI partitioned loading test apparatus as described in any one of claims 1-4, characterized in that, Includes the following steps: Step S1: For the mine where dynamic disaster simulation is to be carried out, conduct on-site testing of the triaxial geostress, ground temperature, gas pressure, and physical and mechanical parameters of the coal seam, roof, and floor. Based on the actual on-site parameters and similarity theory, an experimental plan was developed, and coal and rock specimens were prefabricated (4); Step S2: Open the inner shell (2), put in the coal and rock specimen (4), and install the multi-functional measuring tube (12) and sensor; Step S3: Start the triaxial pressurization device to apply triaxial stress to the coal and rock specimen (4) to simulate the stress distribution law of the three zones in the field; Step S4: Open the gas filling switches of the four multi-functional measuring tubes (12), select the minimum gas pressure according to the formation gas pressure distribution, and simultaneously fill and adsorb different areas of the coal and rock specimen (4) until the adsorption is balanced to the minimum gas pressure, and then close all the gas filling switches; open the gas filling hole (11) and fill the outer shell (1) with gas to maintain the gas pressure balance between the inner and outer shells and the coal and rock specimen (4); Step S5: Turn on the heating switch of the multi-functional measuring tube (12) and heat different areas of the coal and rock specimen (4) according to the formation temperature distribution to present different temperature distributions in different areas; Step S6: When the coal seam stress, temperature and field parameter values ​​are similar, open the gas filling switch of three multi-functional measuring tubes (12) to perform gas filling and adsorption, and keep the gas pressure at the inlet stable according to the gas pressure distribution of the formation. Step S7: Conduct coal mine dynamic disaster simulation tests as needed.

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