Water-filled cavity making device and method

Abstract

The present application belongs to the technical field of tunnel and underground engineering physical model test, and relates to a water-filled cavity making device and method, which comprises a test box, a filling material for simulating rock-soil body arranged in the test box, a mold buried in the filling material for forming a solution cavity, the mold comprising a rubber capsule having an inlet, an ice mold arranged in the rubber capsule, the ice mold being in contact with the inner wall of the rubber capsule, the shape of the ice mold being used for simulating a solution cavity in an actual project, the shape of the ice mold being kept in a predetermined similarity ratio with the shape of the solution cavity, a hole breaking structure for breaking the rubber capsule to lead out water after the solution cavity is formed and the ice mold is watered, and a pulling-out structure connected with the inlet for pulling out the rubber capsule from the solution cavity after the water in the rubber capsule is led out. The present application ensures that the shape of the solution cavity keeps a predetermined similarity ratio with the actual project, and utilizes a forming mold to prefabricate the solution cavity, realizes the diversification of the solution cavity form, greatly improves the test efficiency, and ensures the accuracy of the measured parameters.

Description

Technical Field

[0001] This invention belongs to the field of physical model testing technology for tunnels and underground engineering, specifically relating to a device and method for fabricating water-filled cavities. Background Technology

[0002] With the implementation of the national strategy to build a strong transportation network, the transportation network is expanding deep into the mountainous and karst regions of western China. As a crucial component of this network, tunnel construction in karst areas often encounters various karst geological disasters due to complex engineering and hydrogeological conditions, well-developed karst structures, and active groundwater. Among these, water inrush is the most frequent and extremely dangerous. Such disasters can cause enormous economic losses, seriously endanger the safety of construction workers, and have a severe negative social impact.

[0003] Underground engineering physical model tests are based on similarity theory to reduce the actual project to a simplified model according to a certain similarity ratio, and use various monitoring elements to obtain the evolution law of parameters such as stress field, displacement field, and seepage field within the model, thereby solving practical problems in underground engineering.

[0004] Currently, the physical model test of water inrush in karst tunnels in geomechanics uses a traditional water-filled cavity. The water-filled cavity fabrication device includes a test chamber, which is filled with a similar material simulating the rock and soil mass. Rubber airbags are embedded in the similar material, and the shape of the rubber airbags is used to form a cavity within the similar material. After the cavity is fabricated, pressurized water is filled into the cavity so that the water content and water pressure in the cavity reach the predetermined requirements, thus forming the water-filled cavity for the experiment.

[0005] However, the construction of karst caves mainly involves prefabrication using inflatable rubber airbags. During the prefabrication process, the rubber airbags have limited rigidity and are easily deformed by the pressure of pouring and vibrating similar materials. As a result, the water-filled karst cavity formed is difficult to maintain the predetermined similarity ratio with the actual project, leading to significant errors in the measured parameters. Summary of the Invention

[0006] In view of this, the present invention provides a device and method for making water-filled cavities, which ensures that the shape of the cavities maintains a predetermined similarity ratio with the actual engineering. At the same time, the cavities are prefabricated using molding molds. Since the inner shape of the molding mold can be arbitrarily adjusted to spherical, square, rectangular, ellipsoidal and other irregular structures, the diversification of cavity forms is successfully realized, which greatly improves the experimental efficiency, ensures the accuracy of the measured parameters, and is highly practical and worthy of promotion.

[0007] The technical solution of this invention is:

[0008] A device for fabricating a water-filled cavity includes a test chamber, wherein the test chamber is filled with a filling material for simulating soil and rock masses, and further includes:

[0009] A mold, embedded in the filling material, is used to form a karst cave. The mold includes a rubber bladder with an entrance. An ice mold is placed inside the rubber bladder and contacts the inner wall of the rubber bladder. The shape of the ice mold is used to simulate a karst cave in an actual engineering project, and the shape of the ice mold maintains a predetermined similarity ratio with the shape of the karst cave.

[0010] The perforated structure is used to puncture the rubber bladder through the inlet to drain water after the formation of the cave and the melting of the ice.

[0011] A pull-out structure, connected to the inlet, is used to pull the rubber bladder out of the cave after the water inside the rubber bladder has been drained.

[0012] Preferably, the perforation structure includes a rod or tube with a tip, the length of which is greater than the distance between the bottom surface of the rubber bladder and the upper surface of the test chamber.

[0013] Preferably, the pull-out structure includes a hollow tube, one end of which is fitted onto the inlet, and a sealing connection structure is provided at the connection between the hollow tube and the rubber bladder.

[0014] Preferably, a tube is vertically inserted into the filling material, the tube is fitted outside the hollow tube, the tube has a free end located outside the filling material, the inlet is located inside the tube, and the end of the tube abuts against the rubber bladder;

[0015] A water pressure control system, whose output end is detachably connected to the free end of the pipe body, is used to control the water content and water pressure inside the cave.

[0016] Preferably, the water pressure control system includes a constant pressure water pump placed in the water source, the outlet of the constant pressure water pump is connected to one end of the outlet pipe, the other end of the outlet pipe is connected to the free end of the pipe body, and a valve is also provided on the outlet pipe for controlling the opening and closing of the water circuit.

[0017] A method for fabricating a water-filled cavity, using the aforementioned water-filled cavity fabrication apparatus, includes the following steps:

[0018] The filling material is laid in layers into the test chamber and compacted layer by layer until the filling material in the test chamber reaches the first height.

[0019] Place the mold, wherein the hollow tube is positioned on the upper side of the rubber bladder of the mold;

[0020] Fit the tube body onto the outside of the hollow tube until one end of the tube body comes into contact with the rubber bladder;

[0021] The filling material is laid in layers into the test chamber and compacted layer by layer to fix the position of the rubber bladder until the filling material in the test chamber reaches the second height.

[0022] During the predetermined time period, the filling material in the test chamber is subjected to constant pressure loading until the filling material is shaped.

[0023] Once all the ice inside the rubber bladder has melted into water, drain the water from the rubber bladder.

[0024] Pulling one end of the hollow tube pulls the rubber bladder through the tube body, forming a cavern;

[0025] Pressurized water at a predetermined pressure is injected into the cave to form a water-filled cavity.

[0026] Preferably, the preparation of the mold includes the following steps:

[0027] Place the rubber bladder into the inner cavity of the pre-fabricated melting cavity that can be opened from the top and bottom, and fix the molding mold.

[0028] Water is poured into the rubber bladder through the inlet until it is full, and the inlet on the rubber bladder is sealed with a plug.

[0029] The molding die is frozen for a predetermined time until the water inside the rubber bladder turns into solid ice to form an ice mold.

[0030] Once the ice mold has frozen completely, remove the molding mold and the plug.

[0031] Connect the inlet on the rubber bladder to one end of the hollow tube and seal it.

[0032] Preferably, before embedding the mold, lubricating oil is uniformly coated on the outer surface of the mold's rubber bladder.

[0033] Preferably, draining the water from the rubber bladder includes the following steps:

[0034] A rod or tube with a pointed tip is passed through a hollow tube connected to the rubber bladder to reach the bottom of the bladder, puncturing it and causing the water inside to gradually flow out.

[0035] Preferably, injecting pressurized water at a predetermined pressure into the cavern includes the following steps:

[0036] Seal the free end of the pipe to the outlet pipe, open the valve of the water pressure control system, start the constant pressure water pump to fill with water, fill with the required volume of water, and close the valve after the water volume and water pressure in the cave meet the test requirements.

[0037] The water-filled cavity fabrication device and method provided by this invention solve the problem that in traditional physical model tests, the cavity is difficult to maintain a predetermined similarity ratio with the actual engineering, resulting in large errors in the measured parameters.

[0038] Compared with existing technologies, this invention combines a rubber bladder with an ice mold, giving the whole structure a certain strength, enabling it to withstand certain external loads without deformation and exhibiting high stability. This ensures that the shape of the karst cave maintains a predetermined similarity ratio with the actual engineering. Furthermore, by using a molding die to prefabricate the ice mold and then using the ice mold to prepare the karst cavity, the invention achieves a diverse range of cavity shapes. This greatly improves experimental efficiency, ensures the accuracy of measured parameters, and demonstrates strong practicality, making it worthy of widespread adoption. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0040] Figure 2 This is a structural schematic diagram of the present invention in its usage state;

[0041] Figure 3 This is a partial schematic diagram of the present invention. Figure 1 ;

[0042] Figure 4 This is a partial schematic diagram of the present invention. Figure 2 ;

[0043] Figure 5 This is a partial schematic diagram of the present invention. Figure 3 ;

[0044] Figure 6 This is a partial schematic diagram of the present invention. Figure 4 ;

[0045] Figure 7 This is a partial schematic diagram of the present invention. Figure 5 ;

[0046] Figure 8 This is a partial schematic diagram of the present invention. Figure 6 ;

[0047] Figure 9 This is a partial schematic diagram of the present invention. Figure 7 .

[0048] Figure label:

[0049] 1—Car body; 2—Lun boom; 3—Wire rope; 4—Bug; 5—Manual ladder; 6—Pipe; 7—Rod or tube with a pointed tip; 8—Hollow tube; 9—Epoxy resin layer; 10—Rubber bladder; 11—Filling material; 12—Valve; 13—Water outlet pipe; 14—Constant pressure water pump; 15—Test chamber; 16—Ice mold; 17—Plug; 18—Threaded joint; 19—Cave; 20—Upper hemispherical mold; 21—Connector; 22—Lower hemispherical mold; 23—Reserved hole. Detailed Implementation

[0050] With the implementation of the national strategy to build a strong transportation network, the transportation network is expanding deep into the mountainous and karst regions of western China. As a crucial component of this network, tunnel construction in karst areas often encounters various karst geological disasters due to complex engineering and hydrogeological conditions, well-developed karst structures, and active groundwater. Among these, water inrush is the most frequent and extremely dangerous. Such disasters can cause enormous economic losses, seriously endanger the safety of construction workers, and have a severe negative social impact.

[0051] Underground engineering physical model tests are based on similarity theory to reduce the actual project to a simplified model according to a certain similarity ratio, and use various monitoring elements to obtain the evolution law of parameters such as stress field, displacement field, and seepage field within the model, thereby solving practical problems in underground engineering.

[0052] Currently, the traditional water-filled cavity is used in the physical model test of water inrush in karst tunnels in geomechanics. The water-filled cavity construction device includes a test chamber, which is filled with a similar material that simulates the rock and soil. Rubber airbags are embedded in the similar material. The shape of the rubber airbags is used to form a cavity 19 in the similar material. After the cavity 19 is constructed, pressurized water is filled into the cavity 19 so that the water content and water pressure in the cavity 19 reach the predetermined requirements to form the water-filled cavity in the experiment.

[0053] However, the construction of Cave 19 mainly uses rubber airbags for prefabrication. During the prefabrication process, due to the limited rigidity of the rubber airbags and their susceptibility to deformation caused by the pressure of pouring and vibrating similar materials, the resulting water-filled cavity is difficult to maintain the predetermined similarity ratio with the actual project, resulting in a large error in the measured parameters.

[0054] Based on this, the present invention provides an apparatus and method for fabricating a water-filled cavity to solve the above problems.

[0055] This invention provides a device for manufacturing a water-filled cavity, including a mold. Specifically, the structure of the mold is as follows: Figure 4As shown, it includes a rubber bladder 10 with an inlet. An ice mold 16 is disposed inside the rubber bladder 10. The inner wall of the rubber bladder 10 is in contact with the ice mold 16. The shape of the ice mold 16 is used to simulate the karst cave 19 in the actual project. Its shape is consistent with that of the karst cave 19 in the actual project, and its size is in a predetermined proportion.

[0056] For ease of retrieval and connection, such as Figure 3 and Figure 4 As shown, a hollow tube 8 is connected to the rubber bladder 10. Specifically, a plug 17 is provided on the inlet of the rubber bladder 10, and the inlet of the rubber bladder 10 is fitted with one end of the hollow tube 8. At the connection between the two, there is a sealing connection structure for sealing treatment. The sealing connection structure is an epoxy resin layer 9, which ensures that the two are sealed and forms a tightly connected integral structure.

[0057] The rubber bladder 10 has excellent contractility, which allows it to adapt to implants of different sizes and volumes, as well as to the external shape of the implants.

[0058] like Figures 7 to 9 As shown, in actual use, a pre-formed molding mold with a pre-formed melting cavity is needed to pre-form the rubber bladder 10 containing the ice mold 16. The molding spherical mold includes an upper hemispherical mold 20 and a lower hemispherical mold 22. An inner cavity with the same structure as the actual engineering structure is formed between the upper hemispherical mold 20 and the lower hemispherical mold 22. The shape of the inner cavity of the molding mold can be varied, and the specific shape depends on the actual engineering. Here, a standard spherical inner cavity molding mold is used as an example for explanation.

[0059] During the preparation process, the rubber bladder 10 is placed into the inner cavity of the pre-made melting cavity mold that can be opened from the top and bottom, so that the inlet of the rubber bladder 10 extends to the outside of the reserved hole 23. Then, the upper hemispherical mold 20 and the lower hemispherical mold 22 are fixed by the connector 21. Water is poured into the rubber bladder 10 through the inlet until it is full. The inlet on the rubber bladder 10 is sealed with the plug 17. Finally, the entire molding mold is placed in a freezer and frozen at -25 degrees Celsius for 24 hours until the water inside the rubber bladder 10 turns into solid ice to form an ice mold 16.

[0060] After the ice mold 16 has frozen completely, remove the molding mold and the plug 17. Connect the inlet on the rubber bladder 10 to one end of the hollow tube 8 and seal it with epoxy resin. When the ice mold 16 is placed inside the rubber bladder 10, the mold formed by the combination of the rubber bladder 10 and the ice mold 16 will have a certain strength and can withstand a certain external load without deformation.

[0061] The water-filled cavity test device for underground engineering physical modeling includes a test chamber 15, which is made of rigid material and is mainly used to ensure the stability of the entire device.

[0062] The test chamber 15 is filled with filling material 11, which is used to form the rock structure in the actual project. The pre-made mold is embedded in the filling material 11, which is used to simulate the karst cave 19 in the actual project.

[0063] When placing the above molds, if Figure 2 As shown, the filling material 11 is transferred using a hoisting device. The hoisting device includes a vehicle body 1, a boom 2, a wire rope 3, and a bucket 4. One end of the boom 2 is connected to the vehicle body 1, and the other end of the boom 2 is connected to one end of the wire rope 3. The other end of the wire rope 3 is connected to the bucket 4. This device can be implemented using an existing vehicle-mounted crane or other existing hoisting devices with hoisting functions. Therefore, its structure will not be described in detail in this invention.

[0064] The hoisting device is mainly used for hoisting and transferring the filling material 11. The uniformly mixed filling material 11 is loaded into the bucket 4, and then transported to the vicinity of the model test chamber 15 by the vehicle body 1. It is then laid in layers inside the test chamber 15 and compacted layer by layer. When the filling material 11 in the test chamber 15 reaches the first height, the prefabricated mold is placed in the predetermined position. Before embedding, the outer surface of the rubber bladder 10 is coated with a layer of lubricating oil to facilitate the removal of subsequent devices. At this time, the rubber bladder 10 is located at the first height, and is covered by the hollow tube 8. Install a tube 6, with one end of the tube 6 abutting against the rubber bladder 10. Then, continue to lay the filling material 11 in layers around the rubber bladder 10 and compact each layer to fix the position of the rubber bladder 10. When the filling material 11 in the test chamber 15 reaches the second height, the filling is completed. Apply constant pressure to the upper surface of the filling material 11 in the test chamber 15 for 20 days. During this process, the filling material 11 has been shaped, the ice mold 16 in the rubber bladder 10 has been completely melted into water, and the karst cave 19 in the filling material 11 has been completed.

[0065] At this point, the bottom of the rubber bladder 10 can be punctured using the perforation structure to create a perforation, allowing the water inside the rubber bladder 10 to flow out. Since the water inside the rubber bladder 10 is no longer supported, its volume becomes smaller. At this point, the rubber bladder 10 can be pulled out through the tube 6 by pulling one end of the hollow tube 8 made of rubber.

[0066] Specifically, such as Figure 5 As shown, the perforation structure includes a rod or tube 7 with a pointed tip, the length of which exceeds the embedment depth of the rubber bladder 10. On the one hand, it can be used to detect whether the ice mold 16 inside the rubber bladder 10 has completely melted. On the other hand, it can create a hole at the bottom of the rubber bladder 10, allowing all the ice water inside the rubber bladder 10 to flow out. This method can reduce the volume of the rubber bladder 10, making it easier to remove the rubber bladder 10 from the tube 6. The whole process causes less disturbance to the test.

[0067] In practical use, such as Figure 1 and Figure 6 As shown, a ladder 5 can be installed on one side of the test chamber 15. The ladder 5 allows the test personnel to reach the top of the test chamber 15. After the ice mold 16 inside the rubber bladder has completely melted into water, the test personnel can stand on the top of the test chamber 15 in a convenient position via the ladder 5. Then, a rod or tube 7 with a pointed tip is passed through the hollow tube 8 connected to the rubber bladder 10 to reach the bottom of the rubber bladder 10 and puncture the bottom of the rubber bladder 10, causing the water inside the bladder to gradually flow out, thus causing its volume to gradually decrease. When it shrinks to less than or equal to the diameter of the tube 6, the rubber bladder 10 can be easily removed by pulling the hollow tube 8 that is sealed to it, thereby forming the structure of the cave 19.

[0068] The aforementioned device can be used to create karst caves of different sizes in actual engineering contexts, with a wide range of applications and is closer to actual engineering projects.

[0069] After the above operations are completed, the structure of the cave 19 is formed. At this time, a water pressure control system can be connected to the pipe 6. The water pressure control system is connected to the interior of the cave 19 in the filling material 11. It is mainly used to control the water content and water pressure inside the cave 19.

[0070] Water pressure control system, such as Figure 2 As shown, it includes a miniature constant pressure water pump 14 placed in the water source. The outlet of the constant pressure water pump 14 is connected to one end of the water outlet pipe 13, and the other end of the water outlet pipe 13 is connected to the free end of the pipe body 6, so that the water source can be supplied to the karst cave 19 in the filling material 11. The water content and water pressure inside the karst cave 19 can be adjusted by adjusting the water pressure of the constant pressure water pump 14. The water content and water pressure can be adjusted according to the test requirements to meet the test requirements.

[0071] Specifically, the karst cave 19 is connected to the outside of the test chamber 15 via a pipe body 6, which in turn is connected to one end of the water outlet pipe 13 via a threaded connector 18. A valve 12 is installed between the water outlet pipe 13 and the threaded connector 18. The valve 12 is used to control the flow of water and regulate the amount of water entering the karst cave 19. The water pressure inside the karst cave 19 can be adjusted by regulating the outlet pressure of the constant pressure water pump 14.

[0072] In response to the above-mentioned device, the present invention also proposes a method for manufacturing a water-filled cavity, which mainly includes the following steps:

[0073] The volume of the cavity was calculated based on the size of the actual karst cave 19 and the model similarity ratio. A rubber bladder 10 was placed into the inner cavity of a prefabricated cavity forming mold, with the inlet of the rubber bladder 10 extending beyond the pre-drilled hole 23. The upper hemispherical mold 20 and the lower hemispherical mold 22 were then fixed using connector 21. Water of the same volume calculated based on the similarity ratio was poured into the rubber bladder 10 through its inlet. The inlet on the rubber bladder 10 was sealed using piston 17. Finally, the entire forming mold was placed in a freezer and frozen at -25 degrees Celsius for 24 hours until the water inside the rubber bladder 10 solidified into ice, forming an ice mold 16. After the ice mold 16 was frozen, the forming mold and piston 17 were removed. The inlet on the rubber bladder 10 was connected to one end of the hollow tube 8 and sealed with epoxy resin, thus forming the mold.

[0074] The well-mixed filling material 11 is layered and compacted inside the test chamber 15. When the filling material 11 in the test chamber reaches the first height, the mold is placed. Before embedding the rubber bladder 10, a layer of lubricating oil is applied to its outer surface to facilitate the removal of subsequent devices. At this time, the rubber bladder 10 is located at the first height. A tube 6 is fitted over the hollow tube 8 so that one end of the tube 6 abuts against the rubber bladder 10. Then, the filling material 11 is layered and compacted around the rubber bladder 10. When the filling material 11 in the test chamber 15 reaches the second height, the filling is completed. The upper surface of the filling material 11 in the test chamber 15 is subjected to constant pressure loading for 20 days. During this process, the filling material 11 has solidified, and the ice mold 16 inside the rubber bladder 10 has completely melted into water. The rubber bladder 10 can be punctured with a rod or tube 7 with a pointed tip through the hollow tube 8 connected to the rubber bladder 10, allowing the water inside to flow out slowly. After the water inside the rubber bladder 10 gradually flows out, the hollow tube 8 that is tightly connected to the rubber bladder 10 can be slowly pulled out, thereby realizing the removal of the rubber bladder 10 and completing the production of the cavities 19 in the filling material 11.

[0075] Seal the pipe body 6 to the outlet pipe 13 of the water pressure control system, open the valve 12 of the water pressure control system, turn on the constant pressure water pump 14 to fill with water, fill with the required volume of water, and close the valve 12 after the required water volume and water pressure in the cave 19 are reached.

[0076] The water-filled cavity fabrication device and method provided by this invention solve the problem that in traditional physical model tests, the cavity is difficult to maintain a predetermined similarity ratio with the actual engineering, resulting in large errors in the measured parameters.

[0077] This invention combines a rubber bladder with an ice mold, giving the entire structure sufficient strength to withstand external loads without deformation and ensuring high stability. This guarantees that the shape of the karst cave maintains a predetermined similarity to the actual engineering project. Simultaneously, a molding die is used to prefabricate the ice mold, which is then used to construct the karst cavity. Since the inner shape of the molding die can be arbitrarily adjusted to spherical, square, rectangular, ellipsoidal, and irregular shapes, diverse cavity forms are successfully achieved, better conforming to practical engineering and closely matching the design requirements of actual engineering physical model experiments. The fabrication of the ice mold within the molding die, as well as the puncturing and removal of the rubber bladder, makes the entire process simple, minimizes disturbance to the experiment, and is time-efficient and inexpensive, greatly improving experimental efficiency, ensuring the accuracy of measurement parameters, and demonstrating strong practicality and worthy of promotion.

[0078] The above-disclosed embodiments are merely preferred embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A device for fabricating a water-filled cavity, comprising a test chamber (15), wherein the test chamber (15) is provided with a filling material (11) for simulating soil and rock, characterized in that, Also includes: A mold is embedded in the filling material (11) to form a cave (19). The mold includes a rubber bladder (10) with an entrance. An ice mold (16) is placed inside the rubber bladder (10). The ice mold (16) is in contact with the inner wall of the rubber bladder (10). The shape of the ice mold (16) is used to simulate the cave (19) in the actual project. The shape of the ice mold (16) and the shape of the cave (19) maintain a predetermined similarity ratio. A perforated structure is provided for puncturing the rubber bladder (10) through the inlet to drain water after the cave (19) is formed and the ice mold (16) melts into water; A pull-out structure, connected to the inlet, is used to pull the rubber bladder (10) out of the cavern (19) after the water inside the rubber bladder (10) has been drained. The perforation structure includes a rod or tube (7) with a tip, the length of which is greater than the distance between the bottom surface of the rubber bladder (10) and the upper surface of the test chamber (15); The pull-out structure includes a hollow tube (8), one end of which is fitted onto the inlet, and a sealing connection structure is provided at the connection between the hollow tube (8) and the rubber bladder (10). The tube (6) is vertically inserted into the filling material (11), the tube (6) is fitted outside the hollow tube (8), the tube (6) has a free end located outside the filling material (11), the inlet is located inside the tube (6), and the end of the tube (6) abuts against the rubber bladder (10). The water pressure control system, whose output end is detachably connected to the free end of the pipe body (6), is used to control the water content and water pressure inside the cave (19).

2. The apparatus for fabricating a water-filled cavity according to claim 1, characterized in that, The water pressure control system includes a constant pressure water pump (14) placed in the water source. The outlet of the constant pressure water pump (14) is connected to one end of the outlet pipe (13), and the other end of the outlet pipe (13) is connected to the free end of the pipe body (6). A valve (12) is also provided on the outlet pipe (13), and the valve (12) is used to control the opening and closing of the water circuit.

3. A method for fabricating a water-filled cavity, using the water-filled cavity fabrication apparatus described in claim 2, characterized in that, Includes the following steps: The filling material (11) is laid in layers into the test chamber (15) and compacted layer by layer until the filling material (11) in the test chamber (15) is filled to the first height; Place the mold, wherein the hollow tube (8) is set on the upper side of the rubber bladder (10) of the mold; A tube body (6) is fitted over the hollow tube (8) until one end of the tube body (6) comes into contact with the rubber bladder (10); The filling material (11) is laid in layers into the test chamber (15) and compacted layer by layer to fix the position of the rubber bladder (10) until the filling material (11) in the test chamber (15) reaches the second height; During the predetermined time period, the filling material (11) in the test chamber (15) is subjected to constant pressure loading until the filling material (11) is shaped; Once the ice mold (16) inside the rubber bladder (10) has completely melted into water, drain the water from the rubber bladder (10). Pull one end of the hollow tube (8) to pull the rubber bladder (10) out through the tube body (6) to form a cave (19). Pressurized water at a predetermined pressure is injected into the karst cave (19) to form a water-filled karst cavity.

4. The method for fabricating a water-filled cavity according to claim 3, characterized in that, The preparation of the mold includes the following steps: Place the rubber bladder (10) into the inner cavity of the pre-made melting cavity that can be opened from the top and bottom, and fix the molding mold; Water is poured into the rubber bladder (10) through the inlet until it is full, and the inlet on the rubber bladder (10) is sealed with a plug (17). The molding die is frozen for a predetermined time until the water inside the rubber bladder (10) turns into solid ice to form an ice mold (16). Once the ice mold (16) has frozen completely, remove the molding mold and the plug (17). Connect the inlet on the rubber bladder (10) to one end of the hollow tube (8) and seal it.

5. The method for fabricating a water-filled cavity according to claim 3, characterized in that, Before embedding the mold, lubricating oil is uniformly coated on the outer surface of the rubber bladder (10) of the mold.

6. The method for fabricating a water-filled cavity according to claim 3, characterized in that, The water inside the rubber bladder (10) is drained, including the following steps: A rod or tube (7) with a pointed tip is passed through a hollow tube (8) connected to the rubber bladder (10) to reach the bottom of the rubber bladder (10), puncturing the rubber bladder (10) and causing the water inside the rubber bladder (10) to gradually flow out.

7. The method for fabricating a water-filled cavity according to claim 3, characterized in that, Injecting pressurized water at a predetermined pressure into the cave (19) includes the following steps: Seal the free end of the pipe (6) to the outlet pipe (13), open the valve (12) of the water pressure control system, turn on the constant pressure water pump (14) to fill the water, fill the required volume of water, and close the valve (12) after the water volume and water pressure in the cave (19) meet the test requirements.

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