A similar simulation test system and a similar simulation test method

Abstract

The application discloses a similar simulation test system and a similar simulation test method, which injects sodium hydroxide solution into an upper aquifer and water into a lower aquifer, collects water gushing from a goaf in a liquid storage tank, pours quantitative solution in the liquid storage tank into a sampling reaction tank, slowly adds hydrochloric acid solution with the same concentration into the sampling reaction tank, and observes temperature change in the sampling reaction tank, so that contribution of the upper and lower aquifers to water gushing in the goaf, water gushing amount or water supplementing amount can be determined, and current liquid / water amount of the upper and lower aquifers can be determined, important guiding data for research on aquifer water resource protection is provided, and different protection modes can be selected according to actual water gushing conditions of each layer.

Description

Technical Field

[0001] This invention relates to the field of similarity simulation test technology for coal seam mining, and in particular to a similarity simulation test system and a similarity simulation test method. Background Technology

[0002] During coal mining, when the overlying strata (aquitard) above the coal seam fractures, the mining-induced fissures can connect to aquifers, allowing water from the aquifers to flow into the goaf. The amount of water flowing into the goaf is a crucial parameter when constructing underground reservoirs.

[0003] In existing technologies, the water inflow is determined by collecting water from the goaf during simulation tests, and it is assumed that the inflow is from the nearest aquifer above the coal seam being mined. However, in reality, there may be multiple aquifers above the coal seam. If the mining-induced fractures are too high, they can connect different aquifers.

[0004] Therefore, determining the contribution or replenishment of water from each aquifer to the goaf becomes a necessary research topic. Obtaining the contribution or replenishment of water from each aquifer to the goaf can provide important guiding data for subsequent research on aquifer water resource protection, allowing for the selection of different protection methods based on the actual water inflow situation.

[0005] Existing similar simulation tests have not solved the problem of how to determine the contribution or replenishment of water from each aquifer to the goaf.

[0006] Therefore, it is necessary to provide a similar simulation test system and similar simulation test method that can determine the contribution or replenishment of water from each aquifer to the goaf. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a similar simulation test system and similar simulation test method that can determine the contribution or replenishment of water from each aquifer to the goaf.

[0008] The present invention provides a similar simulation test system, comprising:

[0009] A similar simulation test device includes an upper aquifer and a lower aquifer arranged at intervals, and a lower similar coal seam is located below the lower aquifer;

[0010] The liquid supply device includes an upper liquid supply tank for injecting sodium hydroxide solution into the upper aquifer and a lower water supply tank for injecting water into the lower aquifer; the outlet pipe of the upper liquid supply tank is connected to the upper aquifer, and a first flow meter is connected to the outlet pipe; the outlet pipe of the lower water supply tank is connected to the lower aquifer, and a second flow meter is connected to the outlet pipe.

[0011] A liquid storage tank is used to receive and store water discharged from the similar simulation test device, and a third flow meter is provided at the water inlet of the liquid storage tank;

[0012] A sampling reaction chamber is used to extract a certain amount of water from the storage tank. The sampling reaction chamber is connected to the storage tank through a first pipe. The first pipe is equipped with a fourth flow meter and a first control valve. A temperature sensor is installed in the sampling reaction chamber.

[0013] The reaction solution supply tank contains hydrochloric acid solution of the same concentration as the sodium hydroxide solution, and is used to supply the hydrochloric acid solution to the sampling reaction tank for reaction; the reaction solution supply tank and the sampling reaction tank are connected by a second pipeline, and the second pipeline is equipped with a fifth flow meter and a second control valve;

[0014] When the temperature sensor reaches its maximum value, the second control valve is closed. The sodium hydroxide solution content in the sampling reaction tank is determined based on the amount of hydrochloric acid solution used. Then, the respective contents of sodium hydroxide solution and water in the storage tank are determined, and the respective replenishment amounts of the upper aquifer and the lower aquifer to the goaf are determined.

[0015] In one of the alternative technical solutions, the similarity simulation test system includes a control device;

[0016] The first flow meter, the second flow meter, the third flow meter, the fourth flow meter, the fifth flow meter, the temperature sensor, the first control valve, and the second control valve are respectively connected to the control device via signal connection.

[0017] In one of the optional technical solutions, the sodium hydroxide solution in the upper liquid supply tank and the water in the lower water supply tank contain fluorescent powder respectively;

[0018] When simulating the excavation of the lower similar coal seam, the time when liquid containing fluorescent powder flows into the goaf is counted as the start time of water inrush.

[0019] In one of the alternative technical solutions, the bottom of the housing of the similar simulation test device has a funnel structure;

[0020] The top opening of the funnel structure is equipped with a filter screen, and the lower similar coal seam is located on the filter screen;

[0021] The inlet of the liquid storage tank is connected to the bottom of the funnel structure.

[0022] In one of the alternative technical solutions, there is an upper similar coal seam below the upper aquifer, and the lower aquifer is located below the upper similar coal seam.

[0023] In one of the alternative technical solutions, a set of liquid supply devices is respectively arranged on both sides of the similar simulation test device.

[0024] In one of the alternative technical solutions, the liquid supply device includes a first lifting mechanism and a second lifting mechanism, with the upper liquid supply tank mounted on the first lifting mechanism and the lower water supply tank mounted on the second lifting mechanism.

[0025] In one of the alternative technical solutions, the liquid supply device includes a first supply tank for replenishing the upper liquid supply tank with sodium hydroxide solution and a second supply tank for replenishing the lower water supply tank with clean water.

[0026] The present invention also provides a similarity simulation test method, which uses the similarity simulation test system described in any of the foregoing technical solutions;

[0027] Includes the following steps:

[0028] S1: Sodium hydroxide solution is continuously injected into the upper aquifer using the upper liquid supply tank, and water is continuously injected into the lower aquifer using the lower water supply tank;

[0029] S2: Simulates excavation of a similar lower coal seam;

[0030] S3: When liquid flows into the storage tank, after a preset time delay, stop injecting liquid into the upper aquifer and stop injecting water into the lower aquifer, and calculate the total liquid injection volume V1 and the total water injection volume V2.

[0031] S4: Observe the liquid level in the storage tank. When the liquid level stops rising, calculate the total liquid volume V3 in the storage tank.

[0032] S5: Draw a fixed amount of liquid from the storage tank into the sampling reaction chamber, the sampling amount is V4;

[0033] S6: Continuously and slowly add hydrochloric acid solution from the reaction solution supply tank to the storage tank, and record the amount of hydrochloric acid solution added in real time;

[0034] S7: Observe the temperature in the sampling reaction chamber:

[0035] If the temperature in the sampling reaction chamber remains constant, it indicates that the solution in the sampling reaction chamber is entirely water, and the liquid in the storage tank is also entirely water. Therefore, the water replenishment from the lower aquifer to the goaf is V3, and the liquid replenishment from the upper aquifer to the goaf is 0.

[0036] If the temperature in the sampling reaction chamber first rises and then falls, the amount of hydrochloric acid solution added at the highest temperature in the reaction chamber is obtained as V5, and then the content of sodium hydroxide solution in the sampling reaction chamber is determined to be V5.

[0037] The contents of sodium hydroxide solution (V6) and water (V7) in the storage tank are calculated. Then, it is determined that the amount of liquid replenished from the upper aquifer to the goaf is V6, the amount of water replenished from the lower aquifer to the goaf is V7, the current liquid storage volume of the upper aquifer is V8, and the current water storage volume of the lower aquifer is V9.

[0038] Where, V6 = V3 × V5 / V4, V7 = V3 × (V4 - V5) / V4, V 8＝ V1-V3×V5 / V4, V 9＝ V2-V3×(V4-V5) / V4.

[0039] In one of the alternative technical solutions, the similar simulation test method further includes the following steps:

[0040] After simulating the excavation of a similar lower coal seam, record the start time T1 when liquid begins to flow into the goaf;

[0041] Record the time T2 at which the liquid level in the storage tank stops rising;

[0042] The water inflow per unit time in the goaf is calculated as V3 / (T2-T1).

[0043] The above technical solution has the following beneficial effects:

[0044] The similarity simulation test system and method provided by this invention involve injecting sodium hydroxide solution into the upper aquifer and water into the lower aquifer. After collecting the water inflow from the goaf in the storage tank, a quantitative amount of solution is extracted from the storage tank and transferred to a sampling reaction tank. Then, a hydrochloric acid solution of equal concentration is slowly added to the sampling reaction tank, and the temperature change in the sampling reaction tank is observed. If the temperature in the sampling reaction tank remains approximately constant, it indicates that the contribution or water replenishment from the upper aquifer to the goaf is zero, and the fracture development zone is not connected to the upper aquifer. If the temperature in the sampling reaction tank gradually increases, it indicates that the sodium hydroxide solution in the upper aquifer flows into the storage tank, and the fracture development zone is connected to the upper aquifer. The amount of hydrochloric acid solution added to the sampling reaction chamber when the temperature reaches its maximum value is recorded and determined. This allows for the determination of the sodium hydroxide solution content in the sampling reaction chamber, the proportion of sodium hydroxide solution in the storage tank, and ultimately the content or volume of sodium hydroxide solution in the storage tank. The content or volume of water in the storage tank is also determined, thus identifying the contribution, flow rate, or replenishment of water from the upper and lower aquifers to the goaf. Furthermore, the current storage / water volume of the upper and lower aquifers is determined, providing crucial guiding data for aquifer water resource protection research, enabling the selection of different protection methods based on the actual water inflow conditions of each layer. Attached Figure Description

[0045] The disclosure of this invention will become more readily understood by referring to the accompanying drawings. It should be understood that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings:

[0046] Figure 1 This is a schematic diagram of a similar simulation test system provided in an embodiment of the present invention;

[0047] Figure 2 This is a schematic diagram of the layout of a similar simulation test device;

[0048] Figure 3 This is a schematic diagram of the liquid supply device layout;

[0049] Figure 4 A schematic diagram of the layout of the sampling reaction chamber and the reaction liquid supply chamber;

[0050] Figure 5 A schematic diagram showing a liquid supply device arranged on both sides of a similar simulation test device;

[0051] Figure 6 This is a schematic diagram showing the signal connections between the control device and various electrical components. Detailed Implementation

[0052] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. Identical components are indicated by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, while the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0053] like Figures 1-4 As shown, an embodiment of the present invention provides a similarity simulation test system, comprising:

[0054] The similarity simulation test device 1 includes an upper aquifer 12 and a lower aquifer 13 arranged at intervals, and a lower similar coal seam 15 is located below the lower aquifer 13.

[0055] The liquid supply device 2 includes an upper liquid supply tank 21 for injecting sodium hydroxide solution into the upper aquifer 12 and a lower water supply tank 22 for injecting water into the lower aquifer 13. The outlet pipe 211 of the upper liquid supply tank 21 is connected to the upper aquifer 12, and a first flow meter 212 is connected to the outlet pipe 211. The outlet pipe 221 of the lower water supply tank 22 is connected to the lower aquifer 13, and a second flow meter 222 is connected to the outlet pipe 221.

[0056] The liquid storage tank 3 is used to receive and store the liquid discharged from the similar simulation test device 1. A third flow meter 31 is provided at the inlet of the liquid storage tank 3.

[0057] The sampling reaction chamber 4 is used to extract a certain amount of liquid from the storage tank 3. The sampling reaction chamber 4 is connected to the storage tank 3 through the first pipe 6. The first pipe 6 is equipped with a fourth flow meter 61 and a first control valve 62. The sampling reaction chamber 4 is equipped with a temperature sensor 41.

[0058] The reaction solution supply tank 5 contains hydrochloric acid solution of the same concentration as the sodium hydroxide solution, and is used to supply the hydrochloric acid solution to the sampling reaction tank 4 for reaction. The reaction solution supply tank 5 and the sampling reaction tank 4 are connected by a second pipe 7, which is equipped with a fifth flow meter 71 and a second control valve 72.

[0059] When the temperature of the temperature sensor 41 reaches its maximum value, the second control valve 72 is closed. The content of sodium hydroxide solution in the sampling reaction tank 4 is obtained based on the amount of hydrochloric acid solution used, and then the contents of sodium hydroxide solution and water in the storage tank 3 are obtained. The supply amounts of the upper aquifer 12 and the lower aquifer 13 to the goaf are determined.

[0060] The similarity simulation test system provided by the present invention includes a similarity simulation test device 1, a liquid supply device 2, a liquid storage tank 3, a sampling reaction tank 4, a reaction liquid supply tank 5, a first pipeline 6, a second pipeline 7, a water pump 8, a water pressure gauge 9, etc.

[0061] The similarity simulation test device 1 includes a box 11, with tempered glass on one or more sides for observing the internal conditions. The box 11 contains a lower similar coal seam 15, a lower aquifer 13, and an upper aquifer 12. The lower similar coal seam 15 and the lower aquifer 13 are covered with similar impermeable rock layers, as are the lower aquifer 13 and the upper aquifer 12. A similar overlying rock layer is laid above the upper aquifer 12, and so on. The lower similar coal seam 15 is simulated using multiple plastic pipes (PVC). Extracting these plastic pipes simulates coal seam mining or excavation; the space formed after the pipes are removed is a goaf or a similar goaf. A steel beam that can be opened is located in the box 11 corresponding to the lower similar coal seam 15 to allow for the extraction of the plastic pipes.

[0062] The housing 11 has openings corresponding to the upper aquifer 12 and the lower aquifer 13 for inserting water pipes. The bottom of the housing 11 has a water outlet for draining water that flows into the goaf.

[0063] The liquid supply device 2 includes an upper liquid supply tank 21 and a lower water supply tank 22. The upper liquid supply tank 21 contains a sodium hydroxide solution of a certain concentration, which is used to inject the sodium hydroxide solution into the upper aquifer 12. The concentration of the sodium hydroxide solution is preferably 0.1 mol / L. The outlet pipe 211 of the upper liquid supply tank 21 is connected to the upper aquifer 12, and a first flow meter 212 is connected to the outlet pipe 211 to measure the volume or flow rate of the sodium hydroxide solution injected into the upper aquifer 12. If necessary, a water pump 8 and a pressure gauge 9 can be connected to the outlet pipe 211. The water pump 8 is preferably a variable frequency pump to maintain stable pressure during liquid injection.

[0064] As needed, multiple first water level sensors can be installed around and in the middle of the upper aquifer 12 to determine whether the sodium hydroxide solution has filled the upper aquifer 12.

[0065] The lower water supply tank 22 contains clean water and is used to inject water into the lower aquifer 13. The outlet pipe 221 of the lower water supply tank 22 is connected to the lower aquifer 13, and a second flow meter 222 is connected to the outlet pipe 221 to measure the volume or flow rate of the clean water injected into the lower aquifer 13. If necessary, a water pump 8 and a pressure gauge 9 can be connected to the outlet pipe 221. The water pump 8 is preferably a variable frequency pump to maintain stable pressure during water injection.

[0066] As needed, multiple second water level sensors can be installed around and in the middle of the lower aquifer 13 to determine whether the water has filled the lower aquifer 13.

[0067] The storage tank 3 is connected to the bottom of the tank body 11, and its inlet is directly connected to the outlet of the tank body 11 or connected through a pipe. The storage tank 3 is used to receive and store the liquid discharged from the similar simulation test device 1, that is, the liquid flowing into the goaf after simulating coal seam excavation will be collected in the storage tank 3. A third flow meter 31 is provided at the inlet of the storage tank 3 to measure the volume or flow rate flowing into the storage tank 3.

[0068] A sampling reaction chamber 4 is arranged on one side of the storage tank 3 and is used to take samples from the sampling reaction chamber 4 for reaction experiments. The inlet of the sampling reaction chamber 4 is connected to the storage tank 3 via a first pipe 6. The first pipe 6 is equipped with a fourth flow meter 61, a first control valve 62, a water pump 8, and a water pressure gauge 9. The fourth flow meter 61 is used to measure the volume or flow rate of the liquid flowing into the sampling reaction chamber 4. The first control valve 62 is used to control the opening and closing of the first pipe 6. After extracting a preset volume of liquid from the sampling reaction chamber 4, the first control valve 62 is closed. A temperature sensor 41 is installed in the sampling reaction chamber 4 to monitor the real-time temperature in the sampling reaction chamber 4.

[0069] A reaction solution supply tank 5 is located on one side of the sampling reaction tank 4. The reaction solution supply tank 5 contains hydrochloric acid solution with a concentration equal to, preferably equal to, that of the sodium hydroxide solution (0.1 mol / L). The reaction solution supply tank 5 is connected to the sampling reaction tank 4 via a second pipe 7. The second pipe 7 is equipped with a fifth flow meter 71, a second control valve 72, a water pump 8, and a pressure gauge 9, used to supply the hydrochloric acid solution to the sampling reaction tank 4 for chemical reaction. The fifth flow meter 71 measures the volume or flow rate of the hydrochloric acid solution flowing into the sampling reaction tank 4. The second control valve 72 controls the opening and closing of the second pipe 7. The rate at which the hydrochloric acid solution is supplied to the sampling reaction tank 4 can be adjusted by regulating the frequency of the water pump 8 on the second pipe 7.

[0070] When hydrochloric acid solution and sodium hydroxide solution undergo an acid-base neutralization reaction in sampling reaction tank 4, heat is generated, and the temperature in sampling reaction tank 4 continuously rises. When the temperature reaches its peak and begins to drop, it indicates that the reaction has been completed. At this point, the amount of hydrochloric acid solution used is the content of sodium hydroxide solution in sampling reaction tank 4. In this invention, the content and amount of liquid are measured by volume. Thus, the content ratio of sodium hydroxide solution is obtained, and the amount of sodium hydroxide solution contained in storage tank 3 is calculated. This content of sodium hydroxide solution is the amount of water replenished or contributed by the upper aquifer 12 to the goaf. The total volume of liquid in storage tank 3 minus the content of sodium hydroxide solution is the amount of water replenished or contributed by the lower aquifer 13 to the goaf.

[0071] If the temperature in reaction chamber 4 remains approximately constant during the experiment, it indicates that there is no sodium hydroxide solution in the sampling reaction chamber 4, which means that the fracture development zone is not connected to the upper aquifer 12 during simulated coal mining. The total volume of liquid in storage tank 3 represents the amount of water replenished or contributed by the lower aquifer 13 to the goaf.

[0072] The liquid storage tank 3, reaction tank 4 and reaction liquid supply tank 5 in this invention can be made of glass fixtures. As needed, multiple vertically spaced liquid level sensors can be configured inside, and corresponding scales can be configured on the outside to measure the liquid storage volume, liquid level, liquid intake volume, liquid supply volume, etc. in the fixture.

[0073] The specific steps are as follows:

[0074] The first step is to turn on the water pump 8 on the outlet pipe 211, continuously injecting sodium hydroxide solution into the upper aquifer 12 from the upper supply tank 21. The pressure gauge 9 is observed and maintained at a preset pressure, ensuring stable injection for a preset time to allow the sodium hydroxide solution to fill the upper aquifer 12. The preset time can be selected and set according to the injection flow rate and the area and thickness of the upper aquifer 12. The injection volume of sodium hydroxide solution is measured using the first flow meter 212.

[0075] Turn on the water pump 8 on the outlet pipe 221 to continuously inject water into the lower aquifer 13 using the lower water supply tank 22. Observe the water pressure gauge 9 and maintain the preset pressure, keeping the water injection stable for the preset time until the lower aquifer 13 is filled with clean water. The preset time can be selected and set according to the water injection flow rate and the area and thickness of the lower aquifer 13. The injection volume of clean water is measured by the second flow meter 222.

[0076] The second step involves opening the steel beam behind box 11 and sequentially removing plastic pipes in a pre-set order to simulate excavating the lower similar coal seam 15. The space after removing the plastic pipes is the goaf. The upper similar rock strata and aquitard will also collapse, with some falling into the goaf. During the collapse of the upper similar rock strata and aquitard, fissures will be generated, called water-conducting fissures. The area formed by these fissures is called the fissure development zone.

[0077] The third step involves observing the storage tank 3. After liquid flows into the storage tank 3, a preset time is allowed, such as 5 seconds, 10 seconds, 15 seconds, 1 minute, etc., before stopping the injection of liquid into the upper aquifer 12 and simultaneously stopping the injection of water into the lower aquifer 13. The total injection volume V1 into the upper aquifer 12 and the total injection volume V2 into the lower aquifer 13 are obtained from the first flow meter 212 and the second flow meter 222, respectively.

[0078] The fourth step is to observe the liquid level in storage tank 3. When the liquid level in storage tank 3 stops rising, it indicates that no more water is flowing into storage tank 3. The total liquid volume V3 in storage tank 3 is measured by the third flow meter 31. The total liquid volume V3 is the contribution, inflow, or replenishment of the aquifer to the goaf in this experiment.

[0079] The total liquid volume V3 may be solely the contribution, inflow, or replenishment from the lower aquifer 13, or it may be the combined contribution, inflow, or replenishment from both the upper aquifer 12 and the lower aquifer 13.

[0080] Fifth, turn on the water pump 8 and the first control valve 62 on the first pipeline 6, observe the water pressure gauge 9 and maintain it at the preset pressure to ensure stable liquid extraction, and draw a fixed amount of liquid from the storage tank 3 into the sampling reaction tank 4. The sampling volume can be set as needed. The sampling volume V4 is measured by the fourth flow meter 61.

[0081] Step 6: Open the water pump 8 and the second control valve 72 on the second pipeline 7, observe the pressure gauge 9 and maintain the preset pressure to ensure a stable liquid supply. Slowly add hydrochloric acid solution from the reaction solution supply tank 5 to the storage tank 3. The amount of hydrochloric acid solution added needs to be determined based on the subsequent reactions. The amount of hydrochloric acid solution added is measured and recorded in real time using the fifth flow meter 71.

[0082] Step 7: Observe the temperature change in the sampling reaction chamber 4 using temperature sensor 41.

[0083] If the temperature in sampling reaction chamber 4 remains constant after a period of time, such as 1 minute, 3 minutes, and 5 minutes, it indicates that the solution in sampling reaction chamber 4 is entirely water. This further confirms that the liquid in storage chamber 3 is also entirely water. This means that during the simulated coal seam excavation, the fracture development height did not reach the upper aquifer 12, and the water inflow in the goaf is entirely clear water from the lower aquifer 13. Therefore, the water replenishment from the lower aquifer 13 to the goaf is determined to be V3, and the replenishment from the upper aquifer 12 to the goaf is 0. After obtaining this data, users can specifically protect the mine water in the lower aquifer 13, which is beneficial for strengthening the construction of the fault layer, or for identifying fracture zones and constructing underground reservoirs below them to preserve mine water, etc.

[0084] For example, if 0 < V3 / V2 < 1 / 3, it indicates that the degree of fracture development in the aquitard below the lower aquitard 13 is generally low. In actual construction, it is advisable to construct a partition layer in the aquitard below the lower aquitard 13 to reduce the influence of the fracture development zone and reduce the influx of water from the lower aquitard 13 into the goaf.

[0085] If 1 / 3 ≤ V3 / V2 < 2 / 3, it indicates that the fissures in the aquifer below the lower aquifer 13 are highly developed. In actual construction, it is impossible to prevent water inflow by constructing a fault layer. Therefore, it is recommended to construct one or more underground reservoirs in the goaf area to store mine water.

[0086] If 2 / 3 ≤ V3 / V2, it indicates that the fissures in the impermeable layer below the lower aquifer 13 are highly developed. During actual construction, the water inflow will be large, requiring strengthened support to prevent roof collapse. Constructing an underground reservoir on-site may not be sufficient to store the inflow. It is necessary to utilize previously formed goaf areas to construct underground reservoirs in advance to store the incoming mine water, or to utilize existing underground reservoirs. During construction, it is necessary to lay water pipelines and pumps in advance to transport the incoming mine water to underground reservoirs in other areas.

[0087] If the temperature in sampling reaction chamber 4 first rises and then falls, it indicates that sampling reaction chamber 4 contains a certain amount of sodium hydroxide solution. The reaction between the sodium hydroxide solution and the hydrochloric acid solution causes the temperature in sampling reaction chamber 4 to rise. Once the reaction is complete, the temperature begins to fall. This also indicates that during the simulated coal seam excavation, the fracture development height reaches the upper aquifer 12, and the water inflow in the goaf is a combined inflow from the upper aquifer 12 and the lower aquifer 13. Since the concentrations of the hydrochloric acid solution and the sodium hydroxide solution are equal, according to the chemical formula NaOH + HCl = NaCl + H2O, the amount of hydrochloric acid solution used is the same as the amount of sodium hydroxide solution.

[0088] When the temperature in sampling reaction tank 4 reaches its highest point, it indicates that the reaction between the hydrochloric acid solution and the sodium hydroxide solution is complete. Then, based on the real-time data recorded by the fifth flow meter 71, the amount of hydrochloric acid solution added, V5, at which the temperature in sampling reaction tank 4 is highest is determined. The content of sodium hydroxide solution in sampling reaction tank 4 is then determined to be V5. V5 / V4 is the ratio of sodium hydroxide solution content in sampling reaction tank 4 and storage tank 3, which can be expressed as a volume ratio.

[0089] Then, the sodium hydroxide solution content V6 and the water content V7 in the storage tank 3 are calculated, and the replenishment amount of the upper aquifer 12 to the goaf is determined to be V6, the replenishment amount of the lower aquifer 13 to the goaf is V7, the current liquid storage volume of the upper aquifer 12 is V8, and the current water storage volume of the lower aquifer 13 is V9.

[0090] Where, V6 = V3 × V5 / V4, V7 = V3 × (V4 - V5) / V4, V 8＝ V1-V3×V5 / V4, V 9＝ V2-V3×(V4-V5) / V4.

[0091] The aforementioned current liquid / water volume refers to the current liquid / water content in the aquifer. Of course, there is a possibility that some sodium hydroxide solution in the upper aquifer 12 may flow into the lower aquifer without reaching the goaf, but this does not affect the aforementioned current liquid / water volume data, providing researchers with a valuable reference for their research and judgment.

[0092] The upper aquifer 12 is related to the ecological environment of the surface layer. Therefore, it is necessary to avoid the water level of the upper aquifer 12 dropping too much and affecting the surface ecology.

[0093] Based on the above data, if the inflow of water in the upper aquifer 12 exceeds 1 / 3 and the current liquid / water content is less than 2 / 3, that is, V6 / V1 > 1 / 3 and V8 / V1 < 2 / 3, then a barrier layer needs to be constructed in the impermeable layer below the upper aquifer 12 to reduce the influence of the fracture development zone and thus reduce the drop in water level in the upper aquifer 12.

[0094] When mining the lower coal seam 15, it generally does not cause large-scale water inrush in the upper aquifer 12. The upper aquifer 12 is mainly protected by water-blocking and isolation methods.

[0095] The protection method for the lower aquifer 13 is the same as that described above, and will not be repeated here.

[0096] In summary, the similarity simulation test system provided by this invention involves injecting sodium hydroxide solution into the upper aquifer 12 and water into the lower aquifer 13. After the water from the goaf is collected in the storage tank 3, a quantitative amount of solution is extracted from the storage tank 3 and transferred to the sampling reaction tank 4. Then, a hydrochloric acid solution of the same concentration is slowly added to the sampling reaction tank 4, and the temperature change in the sampling reaction tank 4 is observed. If the temperature in the sampling reaction tank 4 remains approximately constant, it indicates that the contribution or water replenishment from the upper aquifer 12 to the goaf is zero, and the fracture development zone is not connected to the upper aquifer 12. If the temperature in the sampling reaction tank 4 gradually increases, it indicates that the sodium hydroxide solution in the upper aquifer 12 flows into the storage tank 3, and the fracture development zone is connected to the upper aquifer 12. The amount of hydrochloric acid solution added to sampling reaction chamber 4 when the temperature in the sampling reaction chamber 4 reaches its maximum value is recorded and obtained. Then, the sodium hydroxide solution content in sampling reaction chamber 4 is determined, the proportion of sodium hydroxide solution in storage tank 3 is obtained, and finally, the content or volume of sodium hydroxide solution in storage tank 3 is obtained. The content or volume of water in storage tank 3 is determined, and the contribution, inflow, or replenishment of water from the upper and lower aquifers to the goaf is determined. The current liquid / water volume of the upper and lower aquifers is also determined, providing important guiding data for the research on aquifer water resource protection, so as to select different protection methods according to the actual water inflow conditions of each layer.

[0097] In one embodiment, such as Figure 6 As shown, the similar simulation test system includes a control device 10.

[0098] The first flow meter 212, the second flow meter 222, the third flow meter 31, the fourth flow meter 61, the fifth flow meter 71, the temperature sensor 41, the first control valve 62, and the second control valve 72 are respectively connected to the control device 10 via signals.

[0099] In this embodiment, the control device 10 may be a computer, controller, processor, etc., to realize automatic calculation, storage and processing, and display the data on the display screen.

[0100] In one embodiment, the sodium hydroxide solution in the upper supply tank 21 and the water in the lower supply tank 22 contain fluorescent powder.

[0101] When simulating the excavation of a similar lower coal seam 15, the time when liquid containing fluorescent powder flows into the goaf is counted as the start time of water inrush.

[0102] In this embodiment, a certain amount of fluorescent powder is added to the sodium hydroxide solution and the water, respectively. During the experiment, a camera is used to capture the flow path of the sodium hydroxide solution and the water, so as to determine whether the sodium hydroxide solution fills the upper aquifer 12 and whether the water fills the lower aquifer 13. The time when the solution containing fluorescent powder begins to flow into the goaf is recorded as the water inflow start time T1, and the time when no more water flows into the storage tank 3 is recorded as the water inflow end time T2. Thus, the water inflow per unit time in the goaf can be determined as V3 / (T2-T1), which provides necessary reference data for the construction of an underground reservoir.

[0103] In one embodiment, such as Figure 2 As shown, the bottom of the box of the similar simulation test device 1 has a funnel structure 16.

[0104] The top opening of the funnel structure 16 is provided with a filter screen 17, and the lower layer, similar to the coal seam 15, is located on the filter screen 17.

[0105] The inlet of the liquid storage tank 3 is connected to the bottom of the funnel structure 16.

[0106] In this embodiment, a funnel structure 16 is provided at the bottom of the housing 11 to facilitate water collection. A filter screen 17 is provided at the top opening of the funnel structure 16 to perform a filtering function. If necessary, one or more layers of filter screens 17 can be provided in the funnel structure 16 to improve the filtering effect.

[0107] In one embodiment, such as Figures 1-2 As shown, there is an upper similar coal seam 14 below the upper aquifer 12, and the lower aquifer 13 is located below the upper similar coal seam 14.

[0108] In this embodiment, an upper similar coal seam 14 and a lower similar coal seam 15 are set to simulate a situation with multiple coal seams. After simulating the mining of the lower similar coal seam 15, the mining of the upper similar coal seam 14 can be simulated to specifically test the water inflow of the upper aquifer 12, and different protection methods can be formulated according to the size of the water inflow.

[0109] Of course, the descriptions of "upper" and "lower" in the terms "upper similar coal seam 14", "lower similar coal seam 15", "upper aquifer 12" and "lower aquifer 13" in this invention are merely names defined for ease of description and do not represent that there are only two coal seams or two aquifers. Their number can be set according to the actual situation of the mining area.

[0110] In one embodiment, such as Figure 5 As shown, a set of liquid supply devices 2 are respectively configured on both sides of the similar simulation test device 1. During the test, liquid / water is injected synchronously from both sides, which can increase the speed of filling the upper and lower aquifers.

[0111] In one embodiment, such asFigure 3 As shown, the liquid supply device 2 includes a first lifting mechanism 26 and a second lifting mechanism 27. The upper liquid supply tank 21 is installed on the first lifting mechanism 26, and the lower water supply tank 22 is installed on the second lifting mechanism 27.

[0112] The first lifting mechanism 26 and the second lifting mechanism 27 can use multiple hydraulic cylinders to drive the upper liquid supply tank 21 and the lower water supply tank 22 to lift and lower, respectively, to simulate water heads at different heights.

[0113] The first lifting mechanism 26 and the second lifting mechanism 27 can be integrated onto a mounting bracket 25. The mounting bracket 25 includes a bracket base plate 251, a bracket top plate 252, and multiple support legs connecting the bracket base plate 251 and the bracket top plate 252. The first lifting mechanism 26 is mounted on the bracket base plate 251, and the second lifting mechanism 27 is mounted on the bracket top plate 252.

[0114] In one embodiment, such as Figure 1 and Figure 3 As shown, the liquid supply device 2 includes a first supply tank 23 for supplying sodium hydroxide solution to the upper liquid supply tank 21 and a second supply tank 24 for supplying clean water to the lower water supply tank 22.

[0115] In this embodiment, the first replenishment tank 23 is used to replenish the upper supply tank 21 with sodium hydroxide solution, and its output pipeline is equipped with a water pump 8, control valve, etc. When the sodium hydroxide solution in the upper supply tank 21 is used up, the first replenishment tank 23 will replenish it with new sodium hydroxide solution.

[0116] The second replenishment tank 24 is used to replenish the clean water in the lower water supply tank 22. Its output pipe is equipped with a water pump 8, control valves, etc. When the clean water in the lower water supply tank 22 is used up, the second replenishment tank 24 will replenish it with new clean water.

[0117] Combination Figures 1-6 As shown, one embodiment of the present invention provides a similarity simulation test method, which employs the similarity simulation test system described in any of the foregoing embodiments.

[0118] Includes the following steps:

[0119] S1: Sodium hydroxide solution is continuously injected into the upper aquifer 12 using the upper liquid supply tank 21, and water is continuously injected into the lower aquifer 13 using the lower water supply tank 22.

[0120] S2: Simulate excavation of the lower similar coal seam 15.

[0121] S3: When liquid flows into the storage tank 3, after a preset time delay, the injection of liquid into the upper aquifer 12 is stopped, and the injection of water into the lower aquifer 13 is stopped at the same time. The total injection volume V1 and the total water injection volume V2 are calculated.

[0122] S4: Observe the liquid level in the storage tank 3. When the liquid level stops rising, calculate the total liquid volume V3 in the storage tank 3.

[0123] S5: Extract a fixed amount of liquid from the storage tank 3 into the sampling reaction tank 4, with a sampling volume of V4.

[0124] S6: Continuously and slowly add hydrochloric acid solution from reaction solution supply tank 5 to storage tank 3, and record the amount of hydrochloric acid solution added in real time.

[0125] S7: Observe the temperature in sampling reaction chamber 4:

[0126] If the temperature in the sampling reaction chamber 4 remains unchanged, it indicates that the solution in the sampling reaction chamber 4 is all water and the liquid in the storage tank 3 is also all water. Therefore, the water replenishment from the lower aquifer 13 to the goaf is V3 and the liquid replenishment from the upper aquifer 12 to the goaf is 0.

[0127] If the temperature in the sampling reaction chamber 4 first rises and then falls, the amount of hydrochloric acid solution added at the highest temperature in the reaction chamber is obtained as V5, and then the content of sodium hydroxide solution in the sampling reaction chamber 4 is determined to be V5.

[0128] The contents of sodium hydroxide solution V6 and water content V7 in storage tank 3 are calculated, and then it is determined that the amount of liquid replenished from the upper aquifer 12 to the goaf is V6, the amount of water replenished from the lower aquifer 13 to the goaf is V7, the current liquid storage volume of the upper aquifer 12 is V8 and the current water storage volume of the lower aquifer 13 is V9.

[0129] Where, V6 = V3 × V5 / V4, V7 = V3 × (V4 - V5) / V4, V 8＝ V1-V3×V5 / V4, V 9＝ V2-V3×(V4-V5) / V4.

[0130] The similar simulation test method provided by this invention involves injecting sodium hydroxide solution into the upper aquifer 12 and water into the lower aquifer 13. After the water inflow from the goaf is collected in the storage tank 3, a quantitative amount of solution from the storage tank 3 is transferred to the sampling reaction tank 4. Then, a hydrochloric acid solution of the same concentration is slowly added to the sampling reaction tank 4, and the temperature change in the sampling reaction tank 4 is observed. If the temperature in the sampling reaction tank 4 remains approximately constant, it indicates that the contribution or water replenishment from the upper aquifer 12 to the goaf is zero, and the fracture development zone is not connected to the upper aquifer 12. If the temperature in the sampling reaction tank 4 gradually increases, it indicates that the sodium hydroxide solution in the upper aquifer 12 flows into the storage tank 3, and the fracture development zone is connected to the upper aquifer 12. The amount of hydrochloric acid solution added to sampling reaction chamber 4 when the temperature in the sampling reaction chamber 4 reaches its maximum value is recorded and determined. Then, the sodium hydroxide solution content in sampling reaction chamber 4 is determined, the proportion of sodium hydroxide solution in storage tank 3 is obtained, and finally, the content or volume of sodium hydroxide solution in storage tank 3 is determined. The content or volume of water in storage tank 3 is also determined, and the contribution or replenishment of water from the upper and lower aquifers to the goaf is determined. This provides important guiding data for the research on aquifer water resource protection, so as to select different protection methods according to the actual water inflow conditions of each layer.

[0131] In one embodiment, the similar simulation test method further includes the following steps:

[0132] After simulating the excavation of the lower similar coal seam 15, the start time T1 when the liquid begins to flow into the goaf is recorded.

[0133] Record the time T2 when the liquid level in storage tank 3 stops rising.

[0134] The water inflow per unit time in the goaf was calculated to be V3 / (T2-T1), providing necessary reference data for the construction of an underground reservoir.

[0135] As needed, the above technical solutions can be combined to achieve the best technical effect.

[0136] The above are merely the principles and preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several other modifications can be made based on the principles of the present invention, and these modifications should also be considered within the scope of protection of the present invention.

Claims

1. A similar simulation test system, characterized in that, include: A similar simulation test device includes an upper aquifer and a lower aquifer arranged at intervals, and a lower similar coal seam is located below the lower aquifer; The liquid supply device includes an upper liquid supply tank for injecting sodium hydroxide solution into the upper aquifer and a lower water supply tank for injecting water into the lower aquifer; the outlet pipe of the upper liquid supply tank is connected to the upper aquifer, and a first flow meter is connected to the outlet pipe; the outlet pipe of the lower water supply tank is connected to the lower aquifer, and a second flow meter is connected to the outlet pipe. A liquid storage tank is used to receive and store the liquid discharged from the similar simulation test device, and a third flow meter is provided at the inlet of the liquid storage tank; A sampling reaction chamber is used to extract a certain amount of liquid from the storage tank. The sampling reaction chamber is connected to the storage tank through a first pipeline. The first pipeline is equipped with a fourth flow meter and a first control valve. A temperature sensor is installed in the sampling reaction chamber. The reaction solution supply tank contains hydrochloric acid solution of the same concentration as the sodium hydroxide solution, and is used to supply the hydrochloric acid solution to the sampling reaction tank for reaction; the reaction solution supply tank and the sampling reaction tank are connected by a second pipeline, and the second pipeline is equipped with a fifth flow meter and a second control valve; When the temperature sensor reaches its maximum value, the second control valve is closed. The sodium hydroxide solution content in the sampling reaction tank is determined based on the amount of hydrochloric acid solution used. Then, the respective contents of sodium hydroxide solution and water in the storage tank are determined, and the respective replenishment amounts of the upper aquifer and the lower aquifer to the goaf are determined.

2. The similarity simulation test system according to claim 1, characterized in that, Includes control devices; The first flow meter, the second flow meter, the third flow meter, the fourth flow meter, the fifth flow meter, the temperature sensor, the first control valve, and the second control valve are respectively connected to the control device via signal connection.

3. The similarity simulation test system according to claim 1, characterized in that, The sodium hydroxide solution in the upper supply tank and the water in the lower supply tank contain fluorescent powder, respectively. When simulating the excavation of the lower similar coal seam, the time when liquid containing fluorescent powder flows into the goaf is counted as the start time of water inrush.

4. The similarity simulation test system according to claim 1, characterized in that, The bottom of the box of the similar simulation test device has a funnel structure; The top opening of the funnel structure is provided with a filter screen, and at least a portion of the lower similar coal seam is located on the filter screen; The inlet of the liquid storage tank is connected to the bottom of the funnel structure.

5. The similarity simulation test system according to claim 1, characterized in that, Below the upper aquifer is a similar upper coal seam, and the lower aquifer is located below the similar upper coal seam.

6. The similarity simulation test system according to claim 1, characterized in that, The liquid supply device is configured on each of the opposite sides of the similar simulation test device.

7. The similarity simulation test system according to claim 1, characterized in that, The liquid supply device includes a first lifting mechanism and a second lifting mechanism. The upper liquid supply tank is installed on the first lifting mechanism, and the lower water supply tank is installed on the second lifting mechanism.

8. The similarity simulation test system according to claim 7, characterized in that, The liquid supply device includes a first supply tank for replenishing sodium hydroxide solution to the upper liquid supply tank and a second supply tank for replenishing clean water to the lower water supply tank.

9. A similarity simulation test method, characterized in that, The similar simulation test system according to any one of claims 1-8 is adopted; Includes the following steps: S1: Sodium hydroxide solution is continuously injected into the upper aquifer using the upper liquid supply tank, and water is continuously injected into the lower aquifer using the lower water supply tank; S2: Simulates excavation of a similar lower coal seam; S3: When liquid flows into the storage tank, after a preset time delay, stop injecting liquid into the upper aquifer and stop injecting water into the lower aquifer, and calculate the total liquid injection volume V1 and the total water injection volume V2. S4: Observe the liquid level in the storage tank. When the liquid level stops rising, calculate the total liquid volume V3 in the storage tank. S5: Draw a fixed amount of liquid from the storage tank into the sampling reaction chamber, the sampling amount is V4; S6: Continuously and slowly add hydrochloric acid solution from the reaction solution supply tank to the storage tank, and record the amount of hydrochloric acid solution added in real time; S7: Observe the temperature in the sampling reaction chamber: If the temperature in the sampling reaction chamber remains constant, it indicates that the solution in the sampling reaction chamber is entirely water, and the liquid in the storage tank is also entirely water. Therefore, the water replenishment from the lower aquifer to the goaf is V3, and the liquid replenishment from the upper aquifer to the goaf is 0. If the temperature in the sampling reaction chamber first rises and then falls, the amount of hydrochloric acid solution added at the highest temperature in the reaction chamber is obtained as V5, and then the content of sodium hydroxide solution in the sampling reaction chamber is determined to be V5. The contents of sodium hydroxide solution (V6) and water (V7) in the storage tank are calculated. Then, it is determined that the amount of liquid replenished from the upper aquifer to the goaf is V6, the amount of water replenished from the lower aquifer to the goaf is V7, the current liquid storage volume of the upper aquifer is V8, and the current water storage volume of the lower aquifer is V9. Among them,V6=V3×V5 / V4,V7=V3×(V4-V5) / V4,V 8＝ V1-V3×V5 / V4,V 9＝ V2-V3×(V4-V5) / V4.

10. The similarity simulation test method according to claim 9, characterized in that, It also includes the following steps: After simulating the excavation of a similar lower coal seam, record the start time T1 when liquid begins to flow into the goaf; Record the time T2 at which the liquid level in the storage tank stops rising; The water inflow per unit time in the goaf is calculated as V3 / (T2-T1).

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