A similar material simulating tunnel surrounding rock and a preparation method thereof

Abstract

The present application relates to the technical field of similar material, especially to a similar material for simulating tunnel surrounding rock and a preparation method thereof.The preparation method comprises the following steps: determining the physical and mechanical parameters of the similar material according to the types and characteristics of the tunnel surrounding rock, and determining the mechanical parameters of the target similar material; selecting appropriate similar material components and determining the final proportioning result according to the determined mechanical parameters; mixing and stirring the similar material components according to the proportioning result to obtain a mixture of the similar material components; pouring the mixture into a mold, demolding after standing, and curing to obtain the similar material for simulating the tunnel surrounding rock.The raw material components for preparing the similar material are simple and easy to obtain, the preparation method is simple, the strength characteristics of the material can be easily changed by adjusting the similar material components, the surrounding rock of different properties can be simulated, and the application range of the similar material for simulating the surrounding rock is expanded.

Description

Technical Field

[0001] This invention relates to the field of similar materials technology, and in particular to a similar material for simulating tunnel surrounding rock and its preparation method. Background Technology

[0002] In geotechnical engineering, mining engineering, and underground structure research, the mechanical behavior of surrounding rock has a decisive influence on engineering stability. As the load-bearing body and source of load for engineering structures, the deformation characteristics, strength properties, and failure modes of surrounding rock directly affect the long-term safety of underground caverns, tunnels, and roadways. However, due to inherent limitations such as high cost, long cycle, and uncontrollable geological conditions in in-situ tests, researchers often find it difficult to obtain comprehensive and reliable mechanical parameters of surrounding rock through direct testing. Against this backdrop, physical similarity simulation tests, due to their advantages of high repeatability, good parameter controllability, and intuitive observation, have become a key technical means to study the deformation mechanism, failure characteristics, and support effectiveness of surrounding rock. Similar materials, as the material basis for physical simulation tests, directly determine the scientific validity and engineering guidance value of the test results based on the degree of matching between their performance parameters and the prototype rock mass. An ideal similar material should be able to accurately reproduce various mechanical properties of the real rock mass, including but not limited to key indicators such as compressive strength, elastic modulus, Poisson's ratio, internal friction angle, and cohesion, while also considering the complex mechanical behaviors of the rock mass, such as anisotropy, rheological properties, and damage evolution. However, due to the complex composition and varied structure of natural rock masses, developing similar materials that can comprehensively simulate these properties presents a significant challenge. This involves both theoretical breakthroughs in materials science and addressing the feasibility of engineering applications, thus remaining a key focus and challenge in this field of research.

[0003] In existing technologies, some patents simulate the characteristics of surrounding rock under different geological conditions through the combination of composite materials. For example, some studies use a six-component blend of river sand, bentonite, barite powder, etc., to simulate mudstone surrounding rock in tunnels; other schemes use four materials, including fly ash and quartz sand, to simulate the mechanical behavior of Class IV and V surrounding rock; and other technologies reproduce the engineering characteristics of expansive soil surrounding rock based on graded mix proportions of different expansive soils. However, these methods generally suffer from high material costs and complex processes, making it difficult to meet the economic and operational requirements of large-scale model tests. In particular, the requirement for precise proportion control of multi-component materials further increases the difficulty of experimental implementation.

[0004] Therefore, how to prepare a similar material that can simulate the surrounding rock of a tunnel, achieve the specified mechanical properties, and has the advantages of simple preparation process and low cost is a problem that technicians urgently need to solve. Summary of the Invention

[0005] The primary objective of this invention is to provide a similar material for simulating tunnel surrounding rock, which can effectively simulate tunnel surrounding rock and meet the physical and mechanical properties of materials.

[0006] The second objective of this invention is to provide a method for preparing a similar material to simulate tunnel surrounding rock, which has a simple preparation process and low cost.

[0007] This invention provides a method for preparing a similar material to simulate tunnel surrounding rock, comprising the following steps: S1. Determine the physical and mechanical parameters of similar materials based on the type and characteristics of the surrounding rock of the tunnel, and determine the mechanical parameters of the target similar material; S2. Based on the determined mechanical parameters, select appropriate similar material components and determine their final proportions; the similar material components include cementitious materials, sand, and water, wherein the cementitious materials include cement, gypsum, and fly ash; S3. Mix and stir the similar material components according to the proportions to obtain a mixture of similar material components; S4. Inject the mixture into the mold, let it stand, demold it, and cure it to obtain a similar material to the simulated tunnel surrounding rock.

[0008] Preferably, the specific steps of step S3 are as follows: weigh similar material components according to the proportion; mix cement, sand, gypsum and fly ash and pour into a mixer, slowly add water and stir for 25-40 minutes to obtain a mixture.

[0009] Preferably, the specific steps of step S4 are as follows: inject the mixture into the mold, let it stand for 7 days, demold it, and cure it at room temperature for 28 days to obtain a similar material to the simulated tunnel surrounding rock.

[0010] Preferably, in step S4, after curing, the material is subjected to mechanical testing, and the actual test results are compared with the mechanical parameters of the target similar material. The material with the closest compressive strength parameters and modulus parameters is selected to obtain the final similar material for simulating the surrounding rock of the tunnel.

[0011] This invention provides a similar material for simulating tunnel surrounding rock, prepared by the aforementioned method for preparing similar materials for simulating tunnel surrounding rock. The tunnel surrounding rock is Class III surrounding rock, and the mass ratio of cement, sand, gypsum, fly ash, and water is (1.3–1.8):(33.5–38):(0.85–1.2):(4.8–5.35):(4.5–4.8). The amount of water directly affects the material's flowability and workability.

[0012] Preferably, the mass ratio of cement, sand, gypsum, fly ash, and water is 1.5:35:1:5:4.65.

[0013] Preferably, the cement is slag silicate cement with a strength grade of 32.5, an initial setting time of ≥45 min, and a final setting time of ≤10 h.

[0014] Preferably, the sand is medium-coarse manufactured sand with a particle size range of 2.6~3.5mm and an apparent density ≥2500kg / m³. 3 Porosity ≤ 47%.

[0015] Preferably, the gypsum is high-strength gypsum with a density of 2.6~2.8 g / cm³. 3 The final setting time is 15-30 minutes.

[0016] Preferably, the fly ash is extra-grade fly ash with a fineness of ≤12% residue on a 45μm square-hole sieve and a specific surface area ≥700m². 2 / kg.

[0017] Beneficial effects: This invention constructs a complete simulation system for similar materials used in tunnel surrounding rock using conventional engineering materials such as cement, sand, fly ash, gypsum, and water. This material system has significant advantages, including readily available raw materials, economical cost, and simple preparation, and can meet the simulation requirements for the physical and mechanical properties of surrounding rock under different geological conditions.

[0018] This invention achieves precise control of the material's bulk density by scientifically regulating the ratio of sand to fly ash. Simultaneously, based on the optimized selection of sand and gravel particle size, the internal friction characteristics and deformation parameters of the material can be effectively adjusted, and the introduction of fine particles significantly improves the material's compactness. Cement, as a key cementitious component, not only provides the necessary structural strength but also ensures the material's stability in aquatic environments. Gypsum enables independent control of the material's brittle characteristics, a characteristic of which is significant for simulating the failure modes of different rock masses; its ability to improve slurry fluidity also greatly enhances the material's workability. Through the synergistic effect of its components, this material system achieves comprehensive simulation of the multi-scale mechanical behavior of surrounding rock, providing a reliable material basis for tunnel engineering model tests. Its simple preparation process and controllable performance parameters make it promising for both scientific research and engineering practice. Detailed Implementation

[0019] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0020] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 A method for preparing a similar material to simulate tunnel surrounding rock includes the following steps: S1. Based on the type and characteristics of the surrounding rock of the tunnel, determine the physical and mechanical parameters of the similar materials. The mechanical parameters of the target similar material are determined to be one-tenth of those of the simulated material. According to the similarity ratio theory, the geometric similarity ratio is numerically equal to the material strength similarity ratio and the modulus similarity ratio. Considering that it is difficult for similar materials to meet the similarity of all mechanical performance parameters, only the strength and modulus of the material are considered when designing the similar material. Since various simulation tests usually use a 1 / 10 scale for similarity simulation, this embodiment uses a geometric similarity ratio of 1 / 10, and the mechanical parameters of the target similar material are one-tenth of the compressive strength and modulus parameters of the Class III tunnel surrounding rock. The types of surrounding rock and the range of its physical and mechanical properties are mainly determined by the relevant physical and mechanical parameters of Class III surrounding rock, as well as the geometric similarity ratio, gravity similarity ratio, and time similarity ratio. The physical and mechanical parameters mainly include: density, wave velocity, compressive strength, deformation modulus, and wave impedance. The physical and mechanical parameters of Class III surrounding rock are as follows: density 2600 kg / m³ 3 Wave velocity 2402 m / s, compressive strength 30 MPa, elastic modulus 12 GPa, deformation modulus 8.3 GPa, wave impedance 6.25 × 10⁻⁶ 6 kg / m 2 ·s.

[0023] S2. Based on the determined mechanical parameters, select suitable similar material components and determine their final mix proportions; the similar material components include cementitious materials, sand, and water, wherein the cementitious materials include cement, gypsum, and fly ash; the mass ratio between cement, sand, gypsum, fly ash, and water is 1.5:35:1:5:4.65; the cement-sand ratio (cement:gypsum) is 1:23; The cement is slag silicate cement with a strength grade of 32.5, with an initial setting time of ≥45min and a final setting time of ≤10h; The sand is medium-coarse manufactured sand, with a particle size range of 2.6~3.5mm and an apparent density ≥2500kg / m³. 3 Porosity ≤ 47%; The gypsum is high-strength gypsum with a density of 2.6~2.8 g / cm³. 3 Final setting time: 15-30 minutes; The fly ash is of extra-high grade, with a fineness of ≤12% residue on a 45μm square-hole sieve and a specific surface area ≥700m². 2 / kg; The water used is natural water; S3. Weigh out similar material components according to the proportion; mix cement, sand, gypsum, and fly ash, pour into a mixer, slowly add water and stir for 25-40 minutes to obtain a mixture; S4. Inject the mixture into the mold, let it stand for 7 days, then demold it and cure it at room temperature for 28 days to obtain a similar material to the simulated tunnel surrounding rock.

[0024] S5. Perform mechanical tests on the similar material of the simulated tunnel surrounding rock, compare the actual test results with the mechanical parameters of the target similar material, select the similar material of the simulated tunnel surrounding rock with the closest compressive strength parameters and modulus parameters, further clarify the raw material ratio of the similar material, and obtain the final similar material of the simulated tunnel surrounding rock.

[0025] Its mechanical properties meet the following specifications: density 2100 kg / m³ 3 Wave velocity 617 m / s, compressive strength 3.7 MPa, elastic modulus 1.2 GPa, deformation modulus 0.83 GPa, wave impedance 1.30 × 10⁻⁶ 6 kg / m 2 ·s.

[0026] Example 2 A method for preparing a similar material to simulate tunnel surrounding rock differs from Example 1 in that the mass ratio of cement, sand, gypsum, fly ash, and water in step S2 is 1.3:33.5:1.2:5.35:4.8.

[0027] Its mechanical properties meet the following specifications: density 2040 kg / m³ 3 Wave velocity 594 m / s, compressive strength 3.2 MPa, elastic modulus 1.06 GPa, deformation modulus 0.65 GPa, wave impedance 1.21 × 10⁻⁶ m / s 6 kg / m 2 ·s.

[0028] Example 3 A method for preparing a similar material to simulate tunnel surrounding rock differs from Example 1 in that the mass ratio of cement, sand, gypsum, fly ash, and water in step S2 is 1.8:38:0.85:4.8:4.5.

[0029] Its mechanical properties meet the following specifications: density 2217 kg / m³ 3 Wave velocity 689 m / s, compressive strength 4.1 MPa, elastic modulus 1.30 GPa, deformation modulus 0.87 GPa, wave impedance 1.52 × 10⁻⁶ 6 kg / m 2 ·s.

[0030] Comparative Example 1 A method for preparing a similar material to simulate tunnel surrounding rock differs from Example 1 in that the mass ratio of cement, gypsum, fly ash, and water in step S2 is 1.5:35:3:5:4.65, and the mass ratio of cementitious material to sand is 1:23. The mass of fly ash is 500g, and the mass of gypsum is 300g.

[0031] The compressive strength of the obtained product was 4.47 MPa and the deformation modulus was 1.1 GPa.

[0032] Comparative Example 2 A method for preparing a similar material to simulate tunnel surrounding rock differs from Example 1 in that the mass ratio of cement, gypsum, fly ash, and water in step S2 is 1.5:35:2:5:4.65, and the mass ratio of cementitious material to sand is 1:23. The mass of fly ash is 500g, and the mass of gypsum is 200g.

[0033] The compressive strength of the obtained product was measured to be 4.1 MPa, and the deformation modulus was 0.93 GPa.

[0034] Comparative Example 3 A method for preparing a similar material to simulate tunnel surrounding rock differs from Example 1 in that the mass ratio of cement, gypsum, fly ash, and water in step S2 is 1.5:18:1:5:4.65, and the mass ratio of cementitious material to sand is 1:12. The mass of fly ash is 500g, and the mass of gypsum is 100g.

[0035] The compressive strength of the obtained product was 4.87 MPa and the deformation modulus was 1.27 GPa.

[0036] The mechanical property test results of the similar material and Class III surrounding rock are shown in Table 1.

[0037] Table 1

[0038] The mechanical property test results of the materials obtained in Example 1 and Comparative Examples 1-3 are shown in Table 2.

[0039] Table 2

[0040] Table 2 shows that, comparing the test results of the materials obtained in Example 1 and Comparative Example 3, increasing the mortar-cement ratio (increasing cement content) of the similar materials effectively improves their strength, with both compressive strength and elastic modulus increasing. Comparing the test results of the materials obtained in Example 1, Comparative Example 1, and Comparative Example 2, it is shown that increasing the amount of gypsum slightly alters the strength of the similar materials, with a slower increase in compressive strength and deformation modulus. By studying the test results between Comparative Examples 1-3 and Example 1, the roles of each key component in the preparation of the similar materials are clarified.

[0041] The raw material components for preparing similar materials provided by this invention are simple and easy to obtain, and the preparation method is simple. By adjusting the similar material components, the strength characteristics of the material can be easily changed, and surrounding rocks of different property categories can be obtained, thus expanding the applicability of the surrounding rock similar materials simulated by this invention.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a similar material to simulate tunnel surrounding rock, characterized in that, Includes the following steps: S1. Determine the physical and mechanical parameters of similar materials based on the type and characteristics of the surrounding rock of the tunnel, and determine the mechanical parameters of the target similar material; S2. Based on the determined mechanical parameters, select appropriate similar material components and determine their final proportions; the similar material components include cementitious materials, sand, and water, wherein the cementitious materials include cement, gypsum, and fly ash; S3. Mix and stir the similar material components according to the proportions to obtain a mixture of similar material components; S4. Inject the mixture into the mold, let it stand, demold it, and cure it to obtain a similar material to the simulated tunnel surrounding rock.

2. The method for preparing a similar material for simulating tunnel surrounding rock according to claim 1, characterized in that, The specific steps of step S3 are as follows: weigh similar material components according to the proportion; mix cement, sand, gypsum and fly ash and pour into a mixer, slowly add water and stir for 25-40 minutes to obtain a mixture.

3. The method for preparing a similar material for simulating tunnel surrounding rock according to claim 1, characterized in that, The specific steps of step S4 are as follows: inject the mixture into the mold, let it stand for 7 days, then demold it, and cure it at room temperature for 28 days to obtain a similar material to the simulated tunnel surrounding rock.

4. The method for preparing a similar material for simulating tunnel surrounding rock according to claim 1, characterized in that, In step S4, after curing, mechanical tests are performed on the material. The actual test results are compared with the mechanical parameters of the target similar material. The material with the closest compressive strength parameters and modulus parameters is selected to obtain the final similar material for simulating the surrounding rock of the tunnel.

5. A similar material for simulating tunnel surrounding rock, characterized in that, The material is prepared by the method for preparing similar materials for simulating tunnel surrounding rock according to any one of claims 1-4, wherein the tunnel surrounding rock is Class III surrounding rock, and the mass ratio of cement, sand, gypsum, fly ash and water is (1.3–1.8):(33.5–38):(0.85–1.2):(4.8–5.35):(4.5–4.8).

6. The similar material for simulating tunnel surrounding rock according to claim 5, characterized in that, The mass ratio of cement, sand, gypsum, fly ash, and water is 1.5:35:1:5:4.

65.

7. The similar material for simulating tunnel surrounding rock according to claim 5, characterized in that, The cement is slag silicate cement with a strength grade of 32.5, an initial setting time of ≥45 min, and a final setting time of ≤10 h.

8. The similar material for simulating tunnel surrounding rock according to claim 5, characterized in that, The sand is medium-coarse manufactured sand with a particle size range of 2.6~3.5mm and an apparent density ≥2500kg / m³. 3 Porosity ≤ 47%.

9. The similar material for simulating tunnel surrounding rock according to claim 5, characterized in that, The gypsum is high-strength gypsum with a density of 2.6~2.8 g / cm³. 3 The final setting time is 15-30 minutes.

10. The similar material for simulating tunnel surrounding rock according to claim 5, characterized in that, The fly ash is high-grade fly ash with a fineness of ≤12% residue on a 45μm square-hole sieve and a specific surface area ≥700m². 2 / kg.

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