Surrounding rock similar material for simulating active fault crossing tunnel experiment and preparation method

Abstract

The invention relates to the technical field of engineering simulation experiments, in particular to a surrounding rock similar material for simulating an active fault crossing tunnel experiment and a preparation method, and the surrounding rock similar material is prepared from the following raw materials in parts by weight: 50-90 parts of cement, 130-1400 parts of yellow sand, 75-85 parts of bryozoatum, 75-85 parts of vermiculite, 50-90 parts of gypsum and 130-150 parts of water. Glass fibers accounting for 0.3% of the total volume of the raw materials and a water reducing agent accounting for 0.5% of the total mass of the raw materials are further doped into the raw materials of the similar material, cement, gypsum, yellow sand, bryozoatum, vermiculite, the glass fibers and water are adopted as the raw materials for preparing the rock surrounding rock material for simulating the active fault crossing tunnel, the raw materials are easy to obtain, cost is low, and the similar material is suitable for large-scale production. Meanwhile, compared with other existing similar surrounding rock materials, the rock surrounding rock material prepared by the preparation method disclosed by the invention can better simulate the damage and cracking effects of the rock surrounding rock.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engineering simulation experiments, and in particular to a simulation surrounding rock similar material for a tunnel experiment across an active fault and a preparation method. BACKGROUND

[0002] The western and southwestern regions of China are experiencing a peak in tunnel construction, but are facing serious challenges from complex geological conditions, especially the safety risks when crossing fault fracture zones and seismic zones. Fault activity and earthquakes can easily cause geological deformation and stress release, seriously threatening the safety of tunnel structures. However, due to the high difficulty and complexity of the project, prototype tests are often difficult to implement. Scale model tests have become an effective supplementary research method. Scale model tests are based on the similarity theory and can reproduce the main mechanical behavior of real tunnels under fault activity and seismic loads through scale reduction. Although scale model tests can effectively simulate the mechanical and deformation behavior of tunnels, the selection of surrounding rock materials is still a bottleneck.

[0003] In recent years, Chinese researchers have also developed surrounding rock materials for tunnel and fault model experiments and have made corresponding progress. Currently, the surrounding rock materials used in China mainly include the following: 1. Using barite powder and gypsum powder as the main materials, sand, water, and laundry detergent as auxiliary materials; 2. Using coarse quartz sand, medium quartz sand, and iron concentrate powder as the main aggregate, gypsum as the cementing agent, and sodium citrate and water as the additives; 3. Using basalt, sand, and soil as the main materials, and anti-freezing solution as the auxiliary material; 4. Using river sand and gypsum cement as the main materials, and other materials as additives.

[0004] However, the above methods have certain limitations and are generally suitable for rock strata with high strength grades. Secondly, they are limited by high costs or the potential harmfulness of raw materials, making it difficult to meet the needs of large-scale tests. Moreover, they only focus on preparing similar surrounding rock materials that closely resemble the physical and mechanical properties of real soil, ignoring the shear failure characteristics of surrounding rock materials. In large-scale model experiments, they are limited by the shaking table or fault simulation device itself, which has a high breaking force and is difficult to cast and form. SUMMARY

[0005] The present application aims to provide a simulation surrounding rock similar material for a tunnel experiment across an active fault and a preparation method, which aims to solve the problems in the prior art.

[0006] The embodiment of the present application provides a kind of simulation across active fault tunnel experiment surrounding rock similar material, the raw material weight proportion of the surrounding rock similar material is as follows: cement: 50~90 parts, yellow sand: 130~1400 parts, sea float stone: 75~85 parts, vermiculite: 75~85 parts, gypsum: 50~90 parts, and water: 130~150 parts;The raw material of the similar material also mixed with 0.3% of the total volume of raw material glass fiber and 0.5% of the total mass of raw material water reducing agent.

[0007] A kind of simulation across active fault tunnel experiment surrounding rock similar material preparation method, comprising the following steps: Step one, cement, yellow sand, sea float stone, vermiculite are weighed according to predetermined ratio; Step two, glass fiber and cement, gypsum are put into stirrer and mixed evenly, stir 3-5 minutes, during which appropriate amount of water is added, so that it is mixed evenly;Sea float stone, vermiculite, yellow sand, water, water reducing agent are added into the mixer according to the amount, and slowly and uniformly stirred for 5-10 minutes to fully mix them, the rock surrounding rock material in wet state is placed into mold and vibrated on shaking table for 3 minutes; Step three, the rock surrounding rock material in wet state after oscillation is placed in indoor for 24 hours, and the dry rock surrounding rock material is obtained after natural air drying.

[0008] Further, the determination operation of the component ratio in step one is: S1, the similarity ratio of rock surrounding rock material is determined by dimensional analysis method, so as to determine the physical and mechanical parameters of rock surrounding rock material; S2: the composition and ratio of raw materials for preparing rock surrounding rock material are determined by the range of physical and mechanical parameters.

[0009] Further, the physical and mechanical parameters of the rock surrounding rock material include density, elastic modulus, poisson's ratio and compressive strength;The range of physical and mechanical parameters of the rock surrounding rock material is determined by the actual physical and mechanical parameters of the surrounding rock of the to-be-simulated cross-active fault mountain tunnel, density similarity ratio, elastic modulus similarity ratio and geometric similarity ratio.

[0010] Further, the cement is ordinary portland cement 325;The particle size of the yellow sand is 0.25mm~0.5mm;The particle size of the sea float stone is 6~12mm;The particle size of the vermiculite is 2~3mm;The gypsum is building gypsum.

[0011] Further, the glass fiber is short alkali-resistant glass fiber, and the length is 8mm;The water reducing agent is polycarboxylic acid high-performance water reducing agent.

[0012] The beneficial effects of the present application are: the present application adopts cement, gypsum, yellow sand, pumice, vermiculite, glass fiber and water as raw materials to prepare rock surrounding rock material for simulating cross active fault tunnel, the raw materials are easy to obtain and the cost is low; the rock surrounding rock material proposed by the present application can simulate the brittleness of rock, and its physical and mechanical properties are suitable for simulating Ⅵ surrounding rock when the elastic modulus similarity constant is 50, the stress similarity constant is 50, the geometric similarity constant is 20, and the density similarity constant is 2.1; and compared with other existing similar surrounding rock materials, the rock surrounding rock material prepared by the present application can better simulate the damage and cracking effect of rock surrounding rock. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 The flow chart of the surrounding rock material preparation of the present application.

[0014] Figure 2 The stress-strain curve of the rock surrounding rock material prepared in the embodiment 1 of the present application.

[0015] Figure 3 The stress-strain curve of the rock surrounding rock material prepared in the embodiment 2 of the present application.

[0016] Figure 4 The stress-strain curve of the rock surrounding rock material prepared in the embodiment 3 of the present application. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0018] A surrounding rock similar material for simulating cross active fault tunnel experiment, the weight ratio of raw materials of the surrounding rock similar material is: cement: 50-90 parts, yellow sand: 130-1400 parts, pumice: 75-85 parts, vermiculite: 75-85 parts, gypsum: 50-90 parts, and water: 130-150 parts; the raw materials of the similar material also contain 0.3% of glass fiber and 0.5% of water reducing agent in the total volume of raw materials, As Figure 1 shown in a preparation method of a surrounding rock similar material for simulating cross active fault tunnel experiment, specifically including the following steps: Step one: weigh the cement, yellow sand, pumice and vermiculite according to the predetermined ratio; the specific operation of each component ratio is as follows S1: determining the similar ratio of the rock surrounding rock material by dimensional analysis method, so as to determine the preparation of rock surrounding rock material physical and mechanical parameters; S2: determining the composition and proportion of the rock surrounding rock material raw material by the physical and mechanical parameter range; Step two: then put the glass fiber, cement and gypsum into the stirrer and mix evenly, stir for 3-5 minutes, add appropriate amount of water during stirring, and mix evenly; then add sea sponges, vermiculite, yellow sand, water and water reducing agent according to the amount into the stirrer and stir slowly and uniformly for 5-10 minutes to fully mix them, and put the rock surrounding rock material in wet state obtained into the mold and vibrate on the shaking table for 3 minutes; Step three: seal with plastic wrap and stand for 24 hours after initial setting, then demold, and stand for natural air drying to obtain the rock surrounding rock material in dry state; The similar ratio of the rock surrounding rock material is determined by dimensional analysis method, and the physical and mechanical parameters of the rock surrounding rock material are determined by the similar ratio of the actual engineering and the rock surrounding rock material; The physical and mechanical parameters of the rock surrounding rock material include density, elastic modulus, poisson's ratio and compressive strength; The rock surrounding rock material raw material is proportioned by weight, and the weight proportion of cement, yellow sand, sea sponges, vermiculite, gypsum and water is: 50-90, 1300-1400, 75-85, 75-85, 50-90, 130-150; the glass fiber accounts for 0.3% of the total volume, and the water reducing agent accounts for 0.5% of the total mass; The cement is ordinary Portland cement 325; as the cementing material of rock surrounding rock material, it plays a cementing role and provides certain strength and hardness.

[0019] The particle size of the yellow sand is 0.25-0.5mm; as the fine aggregate of rock surrounding rock material, it fills the gap between the coarse framework to form a dense structure.

[0020] The particle size of the sea sponges is 6-12mm; as the coarse aggregate of rock surrounding rock material, it forms a rigid framework with vermiculite to bear the main load.

[0021] The particle size of the vermiculite is 2-3mm; as the coarse aggregate of rock surrounding rock material, it forms a rigid framework with sea sponges to bear the main load.

[0022] The gypsum is building gypsum; as the reinforcing agent of rock surrounding rock material, it improves the strength of rock surrounding rock material.

[0023] The glass fiber is short alkali-resistant glass fiber with a length of 8mm; as the key material for maintaining the integrity of rock surrounding rock material.

[0024] The water reducing agent is a polycarboxylic acid high-performance water reducing agent; as an additive of the rock surrounding rock material, the water-cement ratio can be reduced, the fluidity can be improved, and the structural regularity of the molding can be improved. Embodiment

[0025] 90 g of cement, 90 g of gypsum, and 3 cm3of glass fiber were added to a stirrer, and an appropriate amount of water was added during stirring for 3-5 minutes to mix the glass fiber with the cement and gypsum. Then, 1300 g of yellow sand, 85 g of sea float stone, 85 g of vermiculite, and 8 g of water reducing agent were slowly poured into the stirrer, stirred at 450 rpm, and stirred for 5-10 minutes with a total of 140 g of water to obtain a mixed material in a wet state. The mixed material in the wet state was poured into a molding mold, shaken until fully compacted, sealed with plastic wrap, and left to stand for 24 hours before demolding. The rock surrounding rock material was obtained by natural air drying. The stress-strain curve of the rock surrounding rock material obtained in this example is shown in FIG. 1. Figure 2

[0026] Example 2: Sample 2 90 g of cement, 90 g of gypsum, and 3 cm3of glass fiber were added to a stirrer, and an appropriate amount of water was added during stirring for 3-5 minutes to mix the glass fiber with the cement and gypsum. Then, 1350 g of yellow sand, 80 g of sea float stone, 80 g of vermiculite, and 8 g of water reducing agent were slowly poured into the stirrer, stirred at 450 rpm, and stirred for 5-10 minutes with a total of 130 g of water to obtain a mixed material in a wet state. The mixed material in the wet state was poured into a molding mold, shaken until fully compacted, sealed with plastic wrap, and left to stand for 24 hours before demolding. The rock surrounding rock material was obtained by natural air drying. The stress-strain curve of the rock surrounding rock material obtained in this example is shown in FIG. 2. Figure 3

[0027] Example 3: Sample 3 90 g of cement, 90 g of gypsum, and 3 cm3of glass fiber were added to a stirrer, and an appropriate amount of water was added during stirring for 3-5 minutes to mix the glass fiber with the cement and gypsum. Then, 1400 g of yellow sand, 75 g of sea float stone, 75 g of vermiculite, and 8 g of water reducing agent were slowly poured into the stirrer, stirred at 450 rpm, and stirred for 5-10 minutes with a total of 150 g of water to obtain a mixed material in a wet state. The mixed material in the wet state was poured into a molding mold, shaken until fully compacted, sealed with plastic wrap, and left to stand for 24 hours before demolding. The rock surrounding rock material was obtained by natural air drying. The stress-strain curve of the rock surrounding rock material obtained in this example is shown in FIG. 3. Figure 4

[0028] The performance of the simulated cross-activity fault tunnel mountain rock surrounding rock material prepared in Examples 1-3 is shown in Table 1:​​​ The density was measured by electronic balance, the elastic modulus and Poisson's ratio were measured by rock uniaxial compression experiment, and the compressive strength was measured by rock uniaxial compression experiment. The test results are shown in Table 1 below: Table 1 Performance comparison

[0029] The above embodiments are not limiting to the present application, unless otherwise explicitly specified and limited, the terms "arrange", "mount", "connect", "connect" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances. The present application is also not limited to the above examples, and the changes, modifications, additions or replacements made by those skilled in the art within the scope of the technical solutions of the present application also belong to the protection scope of the present application. In addition, the technical features involved in the different embodiments of the present application described above can be combined with each other as long as they do not conflict with each other.

[0030] For those skilled in the art, it is obvious that the present application is not limited to the details of the above exemplary embodiments, and the present application can be realized in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application is defined by the appended claims rather than the above description, therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims involved.

Claims

1. A similar material for surrounding rock of a simulated tunnel across an active fault, characterized in that: The weight ratio of the raw materials of the surrounding rock similar material is: cement: 50 to 90 parts, yellow sand: 130 to 1400 parts, pumice: 75 to 85 parts, vermiculite: 75 to 85 parts, gypsum: 50 to 90 parts, and water: 130 to 150 parts; the raw materials of the similar material are also mixed with glass fiber accounting for 0.3% of the total volume of the raw materials and a water reducer accounting for 0.5% of the total mass of the raw materials.

2. A method for preparing similar surrounding rock materials for simulating tunnel experiments across active faults, characterized in that: The following steps are involved: Step 1: Weigh cement, sand, pumice and vermiculite according to a predetermined ratio; Step 2: Put the glass fiber, cement and gypsum into a blender and mix them evenly. Stir for 3-5 minutes, during which time add an appropriate amount of water to mix them evenly. Then add the pumice, vermiculite, yellow sand, water and water reducer according to the amount into the blender and stir slowly and evenly for 5-10 minutes to fully mix them. Put the obtained wet rock surrounding rock material into a mold and vibrate on a shaker for 3 minutes. Step 3: Place the rock surrounding rock material in a wet state that has been evenly vibrated indoors for 24 hours, then remove the mold and allow it to dry naturally to obtain the rock surrounding rock material.

3. The method for preparing similar surrounding rock materials for simulating tunnel experiments across active faults according to claim 2, characterized in that: The operation for determining the allocation ratio of each group in step 1 is as follows: S1. Determine the similarity ratio of rock surrounding materials by dimensional analysis method, so as to determine the physical and mechanical parameters of rock surrounding materials; S2: Determine the composition and proportion of the raw materials for preparing the rock surrounding rock material within the range of the physical and mechanical parameters.

4. The method for preparing similar surrounding rock materials for simulating tunnel experiments across active faults according to claim 3, characterized in that: The physical and mechanical parameters of the rock surrounding rock material include density, elastic modulus, Poisson's ratio, and compressive strength; the range of the physical and mechanical parameters of the rock surrounding rock material is determined by the actual physical and mechanical parameters, density similarity ratio, elastic modulus similarity ratio, and geometric similarity ratio of the surrounding rock of the mountain tunnel across the active fault to be simulated.

5. The method for preparing similar surrounding rock materials for simulating tunnel experiments across active faults according to claim 2, characterized in that: The cement is ordinary Portland 325 cement; the particle size of the yellow sand is 0.25mm-0.5mm; the particle size of the pumice is 6-12mm; the particle size of the vermiculite is 2-3mm; and the gypsum is building gypsum.

6. The method for preparing similar surrounding rock materials for simulating tunnel experiments across active faults according to claim 2, characterized in that: The glass fiber is short-cut alkali-resistant glass fiber with a length of 8 mm; the water reducer is a polycarboxylic acid high-performance water reducer.

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