An indoor fire source loading method for simulating real fire in underground tunnels

Abstract

The application discloses an indoor fire source loading method for simulating real fire in an underground tunnel, S1: processing a test rock block in the shape of a cuboid; S2: selecting rock blocks as bases and placing the test rock block above the two bases with a distance between the two bases, so as to form a structure similar to a "pin" character; S3: setting a heating groove in the space between the two bases and the bottom surface of the test rock block; S4: spraying fireproof materials at the intersection gap between the bottom of the left and right side walls of the test rock block and the two bases, and at the intersection gap between the bottom of the front and back wall surfaces of the test rock block and the heating groove; S5: placing combustion materials in the heating groove and performing open fire source damage loading; and S6: extinguishing the open fire source and performing post-processing on the test rock block. The method can effectively realize single-side open fire loading on the rock block in a laboratory scale, is closer to the actual situation that the single-side wall of surrounding rock is affected by fire, and is more reasonable and intuitive for simulating and studying rock open fire damage in real fire in an underground tunnel.

Description

Technical Field

[0001] This invention belongs to the field of tunnel rock mass engineering technology, specifically relating to an indoor fire source loading method for simulating a real fire in an underground tunnel, which can be widely used in laboratory-scale rock strength testing, deep mineral resource mining, and deep-buried tunnel construction. Background Technology

[0002] In numerous geotechnical engineering applications, such as underground coal gasification, geothermal energy extraction, and radioactive waste treatment, rocks are often subjected to high-temperature conditions, altering their internal structure and mechanical properties. Furthermore, tunnels and stone structures also face the threat of high temperatures caused by fires, especially the damage from open flames, which significantly impacts the deformation and stability of the surrounding rock. Therefore, studying the effects of open flames on rock mechanical behavior and damage development is crucial.

[0003] Rocks are typically heterogeneous materials, exhibiting complex physical and mechanical behaviors due to variations in mineral composition, grain size, and microstructure. Generally, the localized thermal stress between minerals with different coefficients of thermal expansion induces the formation and coalescence of internal microcracks, causing changes in the compressive strength, elastic modulus, p-wave velocity, peak strain, porosity, permeability, and resistivity of thermally damaged rocks with temperature. Furthermore, rocks will suffer varying degrees of damage under open flame loading at different distances or for different durations. In recent years, numerous experimental studies have been conducted on the effects of thermal damage on the properties of different rock types. However, most indoor tests on thermally damaged rocks utilize electric furnace heating to generate omnidirectional, uniform thermal stress. In practical engineering scenarios, such as tunnels experiencing fires, the surrounding rock is only damaged on one side wall by open flame, which differs significantly from electric furnace heating. Figure 1 As shown. Therefore, the currently widely used electric furnace heating method cannot realistically simulate the changes in the surrounding rock of a fire-prone tunnel. Summary of the Invention

[0004] In view of this, the present invention aims to provide a simple and easy-to-implement indoor fire source loading method for simulating real fires in underground tunnels, which is similar to the actual application scenario of tunnel rocks in fire accidents, and provides a new method for studying the properties of engineering rocks in fire environments.

[0005] To achieve the above objectives, this invention proposes an indoor fire source loading method for simulating a real fire in an underground tunnel, comprising the following steps:

[0006] S1: Select rock blocks of suitable material according to research needs and process them into complete rectangular test rock blocks;

[0007] S2: Select two rock blocks of the same material as the bases and place them at a certain distance apart left and right. Place the test rock block above the two bases, leaving part of the bottom surface suspended, forming a structure similar to the Chinese character "pin".

[0008] S3: Set up a heating tank in the space separated from the bottom surface of the test rock block between the two bases.

[0009] S4: Spray fireproof materials along the intersection gaps between the bottom of the left and right side walls of the test rock block and the two bases, and along the intersection gaps between the bottom of the front and rear wall surfaces of the test rock block and the heating tank, to prevent the subsequent open fire source from directly burning the four side walls of the test rock block.

[0010] S5: Place combustion materials in the heating tank and conduct open fire source damage loading to meet the open fire temperature during a fire.

[0011] S6: After the open fire source damage loading is completed, extinguish the open fire source and conduct post-treatment on the test rock block.

[0012] As a preference of the above solution, in step S1, the size of the test rock block is 600 mm in the front-back length × 150 mm in the left-right length × 300 mm in height.

[0013] Further preferably, in step S2, the material of the base is the same as that of the test rock block and they are from the same origin.

[0014] Further preferably, in step S3, the heating tank is an iron heating tank and has a handle.

[0015] Further preferably, in step S3, the height of the heating tank is adjustable to simulate different distances between the open fire source and the tunnel surrounding rock during an actual fire; the heating tank can be blown to increase the combustion temperature to simulate different temperatures generated at different stages during an actual fire.

[0016] Further preferably, in step S4, the front and rear ends of the base extend outside the front and rear ends of the test rock block, and the front and rear ends of the heating tank are located inside the front and rear ends of the test rock block.

[0017] Further preferably, in step S5, the combustion material is charcoal, and the combustion temperature of the charcoal is as high as 750 - 1100 °C.

[0018] Further preferably, in step S6, the post-treatment of the test rock block is natural cooling or impact water pressure cooling or drilling and cutting.

[0019] The beneficial effects of the present invention are: It can effectively achieve single-sided open fire loading of rock blocks at the laboratory scale, which is closer to the actual situation of the single side wall of the surrounding rock affected by fire, and it is more reasonable and intuitive to use it to simulate and study the real fire rock open fire damage in underground tunnels. Description of the Drawings

[0020] Figure 1 Schematic diagram of open fire damage to the side wall of a tunnel in practice;

[0021] Figure 2 Schematic diagram of single-sided open fire damage loading of rock blocks at the laboratory scale;

[0022] Figure 3 is Figure 2 three-dimensional view of. Specific implementation manner

[0023] To describe the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0024] In conjunction with Figure 2 、 Figure 3 As shown, an indoor fire source loading method for simulating a real fire in an underground tunnel includes the following steps:

[0025] S1: Select a rock block with appropriate material according to research needs and process it into a complete cuboid test rock block 1.

[0026] Preferably, the size of the test rock block 1 is 600 mm in the front-back length × 150 mm in the left-right length × 300 mm in height. The material of the rock block is selected according to the origin required by the research, and the size can also be processed into corresponding specifications according to the research requirements.

[0027] S2: Select two rock blocks of the same material as the base 2 and place them at a certain distance apart left and right. Place the test rock block 1 above the two bases 2, leaving part of the bottom surface suspended, forming a structure similar to a "pin" character.

[0028] Preferably, the material of the base 2 is the same as that of the test rock block 1 and comes from the same origin; selecting the same origin can simulate the actual situation as much as possible to avoid different thermal stresses generated between other materials and the rock material of the test rock block.

[0029] S3: Set up a heating groove 3 in the space separated from the bottom surface of the test rock block 1 between the two bases 2 for placing combustion materials to simulate an open fire source.

[0030] Preferably, the heating groove 3 is an iron heating groove and has a handle, which can be pushed into the lower space of the test rock block and pulled out after the test loading is completed. Further, the height of the heating groove can be adjusted to simulate different distances between the open fire source and the tunnel surrounding rock during an actual fire; the heating groove can be subjected to air blowing operation to increase the combustion temperature to simulate different temperatures generated at different stages during an actual fire.

[0031] S4: Fireproof material 4 is sprayed along the bottom of the left and right side walls of the test rock block 1 and the intersection of the two bases 2, and along the bottom of the front and rear walls of the test rock block 1 and the intersection of the heating groove 3, to prevent subsequent open flame sources from directly burning the four side walls of the test rock block, in order to create a real tunnel open flame source causing thermal damage to the side wall rocks.

[0032] Ideally, the front and rear ends of the base 2 extend beyond the front and rear ends of the test rock block 1, while the front and rear ends of the heating groove 3 are located inside the front and rear ends of the test rock block; this facilitates the subsequent spraying of fireproof materials and prevents the open flame from burning the sidewalls of the rock block when an open flame source is applied.

[0033] S5: Place combustible materials in the heating tank 3 and apply open flame damage to meet the open flame temperature in the event of a fire.

[0034] The combustion material can be charcoal, which burns at temperatures as high as 750-1100℃, meeting the open flame temperature requirements during a fire. Alternatively, other combustion materials can be used, depending on the research needs, to adapt to the different temperatures of different actual fires.

[0035] S6: After the open flame source damage loading is completed, the open flame source is extinguished and the test rock block is post-processed.

[0036] The post-treatment of the test rock blocks can be natural cooling, water pressure cooling, or drilling and cutting, depending on the research objective.

Claims

1. An indoor fire source loading method simulating a real fire in an underground tunnel, characterized by, The method comprises the following steps: S1: selecting rock blocks with appropriate material according to research needs and processing them into complete cuboid test rock blocks; S2: selecting two rock blocks with the same material as the base and placing them at a distance apart, and placing the test rock block above the two bases, leaving part of the bottom surface suspended, to form a structure similar to a "pin" character; S3: setting a heating groove in the space between the two bases and the bottom surface of the test rock block; the height of the heating groove can be adjusted to simulate the different distances between the open fire source and the surrounding rock of the tunnel during actual fire occurrence; the heating groove can be operated to blow air to increase the burning temperature, to simulate the different temperatures produced at different stages during actual fire occurrence; S4: spraying fireproof material along the intersection gap between the bottom of the left and right side walls of the test rock block and the two bases, and along the intersection gap between the bottom of the front and rear walls of the test rock block and the heating groove, to prevent the subsequent open fire source from directly burning the four side wall surfaces of the test rock block; S5: placing burning materials in the heating groove and performing open fire source damage loading to meet the open fire temperature during fire occurrence; S6: after the open fire source damage loading is completed, extinguishing the open fire source and performing post-processing on the test rock block.

2. The method of claim 1, wherein: In the S1 step, the size of the test rock block is 600mm in front and back length, 150mm in left and right length, and 300mm in height.

3. The method of claim 1, wherein: In the S2 step, the base has the same material as the test rock block and comes from the same production area.

4. The method of claim 1, wherein: In the S3 step, the heating groove is an iron heating groove with a handle.

5. The method of claim 1, wherein: In the S4 step, the front and rear ends of the base extend outside the front and rear ends of the test rock block, and the front and rear ends of the heating groove are located inside the front and rear ends of the test rock block.

6. The method of claim 1, wherein: In the S5 step, the burning material is charcoal fire, and the temperature of the charcoal fire burning is as high as 750-1100℃.

7. The method of claim 1, wherein: In the S6 step, the post-processing of the test rock block is natural cooling or impact water pressure cooling or drilling and cutting.

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