Concrete for annular lining structure of tunnel as well as preparation method and construction method of concrete

Abstract

The invention discloses concrete for an annular lining structure of a tunnel as well as a preparation method and a construction method of the concrete. The concrete is prepared from 246 parts by weight of cement, 160 parts by weight of water, 78 parts by weight of mineral powder, 77 parts by weight of fly ash, 753 to 801 parts by weight of sand, 978 to 1026 parts by weight of gravel, 4.63 to 4.81 parts by weight of a water reducing agent and 20 parts by weight of an expanding agent. According to the concrete for the annular lining structure of the tunnel, through the action of various materials in the formula, the prepared concrete has the advantages in early strength, durability, impermeability and crack resistance, so that the service life of the tunnel structure is prolonged; the durability defects of alkali aggregate reaction, chloride ion erosion, carbonization and the like of the existing concrete are overcome, the service life of the concrete is short, and the defects of vibration leakage, cold joints, honeycombs, top cavities and the like in the construction process along with the acceleration of the construction rhythm are overcome.

Description

Technical Field

[0001] The invention relates to the field of building materials, and in particular to concrete for a tunnel annular lining structure and a preparation method thereof. Background Art

[0002] In railway tunnels, structural defects emerge in an endless stream. The most prominent problems are the hollowing out, looseness, collapse of construction joints, falling blocks of concrete in the arch, cracks, and even seepage and leakage of tunnel lining vaults, which seriously threaten the driving safety of high-speed railways and restrict the rapid development of railway transportation. In the case of fluctuations in the market of concrete raw materials and unreasonable adjustments in mix design, concrete has durability defects such as alkali-aggregate reaction, chloride ion corrosion, and carbonization, which affect the service life of concrete; and as the construction pace accelerates, quality problems such as vibration leakage, cold joints, honeycombs, and top voids during construction will eventually affect the later operation of the entire tunnel. When using the shield method to excavate a tunnel, the shield shell and lining segments are used to support the surrounding rock and soil to prevent collapse while the shield machine advances the excavation. The advantage of the synchronous lining structure is to ensure the safety of the tunnel structure. It is crucial to develop concrete materials suitable for the synchronous lining structure of the shield tunnel for different working conditions. To this end, it is extremely important to study a concrete with good workability, high density, low collapse, high early strength, strong durability and crack resistance, and the ability to improve the service life of the tunnel structure. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a concrete for a tunnel annular lining structure and a preparation method and a construction method thereof, which overcome the durability defects of existing concrete such as alkali-aggregate reaction, chloride ion corrosion, carbonization, etc. The service life of concrete is short, and as the construction pace accelerates, defects such as vibration leakage, cold joints, honeycombs, and top voids occur during construction.

[0004] The present invention provides a concrete for a tunnel annular lining structure, wherein the concrete for a tunnel annular lining structure comprises:

[0005] 246 parts by weight of cement, 160 parts by weight of water, 78 parts by weight of mineral powder, 77 parts by weight of fly ash, 753 to 801 parts by weight of sand, 978 to 1026 parts by weight of crushed stone, 4.63 to 4.81 parts by weight of water reducing agent, and 20 parts by weight of expansion agent.

[0006] Optionally, the cement is ordinary Portland cement with a strength of 42.5, and the ordinary Portland cement includes tricalcium silicate, dicalcium silicate, and tricalcium aluminate, and the weight ratio of the tricalcium silicate, dicalcium silicate, and tricalcium aluminate is 6:3:1.

[0007] Optionally, the type of the mineral powder is S95, and the activity index of the mineral powder is greater than 95.

[0008] Optionally, the fly ash is Class C Grade II, the water requirement ratio of the fly ash is ≤105%, and the stability of the fly ash is ≤5.0mm.

[0009] Optionally, the fineness modulus of the sand is between 2.3-3.0, the mud content of the sand is ≤2.0wt%, the mud block content of the sand is ≤1.0wt%, and the sand includes natural river sand or lake sand with a chloride ion content of ≤0.002wt%.

[0010] Optionally, the crushed stone is gravel with a particle size of 5mm-25mm, the content of needle-like particles in the crushed stone is less than 5wt%, the mud content in the crushed stone is less than 0.8wt%, and the content of mud blocks in the crushed stone is less than 0.5wt%; wherein, the crushed stone includes 308 parts by weight of gravel with a particle size of 5mm-16mm and 718 parts by weight of gravel with a particle size of 16mm-25mm, or the crushed stone includes 293 parts by weight of gravel with a particle size of 5mm-16mm and 685 parts by weight of gravel with a particle size of 16mm-25mm.

[0011] Optionally, the water reducer is a polycarboxylate high-efficiency water reducer, and the polycarboxylate high-efficiency water reducer comprises 20wt%-30wt% of modified phosphate.

[0012] Optionally, the weight of the 20wt%-30wt% modified phosphate is 1.2% of the sum of the weights of the cement, fly ash and mineral powder.

[0013] Optionally, the expansion agent is one or more of gypsum, lime, and aluminum powder.

[0014] In addition, the present invention also provides a method for preparing concrete, which is used to prepare the concrete for the tunnel annular lining structure as described above, and the preparation method comprises:

[0015] According to the formula, cement, mineral powder, fly ash and expansion agent are uniformly mixed and stirred for 30 seconds, then sand and crushed stone are added and stirred for 30 seconds, and after the dry materials are evenly mixed, water and water reducing agent are added and stirred for 1 minute to obtain the concrete for the tunnel annular lining structure.

[0016] In addition, the present invention also provides a concrete construction method, which is used to cast the concrete for the tunnel annular lining structure on site, and the construction method comprises:

[0017] a. Pour the concrete symmetrically in layers from bottom to top, with each layer pouring height less than or equal to 30 cm, and fully vibrate with an attached plate vibrator and a manual insertion vibrator;

[0018] b. The pouring sequence of each layer should start from the end where the concrete has been constructed to ensure the joint quality of the concrete construction joint and facilitate exhaust;

[0019] c. Remove the mold after 24-36 hours. After the mold is removed, the concrete should be cured immediately. Use special personnel to sprinkle water. The curing time is greater than or equal to 14 days;

[0020] d. When lining the arch wall, first retract the side walls on both sides to the middle, and then slowly lower the trolley to prevent the side walls from sticking to the mold. After demolding is completed, clean the template with a high-pressure water gun and apply demolding oil for the next cycle.

[0021] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0022] The concrete for the tunnel annular lining structure provided by the embodiment of the present invention comprises 246 parts by weight of cement, 160 parts by weight of water, 78 parts by weight of mineral powder, 77 parts by weight of fly ash, 753 parts by weight to 801 parts by weight of sand, 978 parts by weight to 1026 parts by weight of crushed stone, 4.63 parts by weight to 4.81 parts by weight of water reducing agent, and 20 parts by weight of expansion agent. The concrete for the tunnel annular lining structure of the present invention has advantages in early strength, durability, impermeability and crack resistance through the interaction between various materials in the formula, thereby improving the service life of the tunnel structure.

[0023] In addition, the method for preparing concrete provided by the embodiment of the present invention is simple and easy to operate.

[0024] In addition, the concrete construction method provided by the embodiment of the present invention can complete the pouring of lining structure concrete under the conditions of narrow space and multiple working surfaces, avoiding defects such as cold joints, color difference, cracks, and voids on the surface of the lining structure concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a later effect diagram of Example 2 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0026] As described in the background technology, in the prior art, tunnel lining vaults are hollow, not dense, construction joints are crushed, vault concrete blocks fall off, cracks occur, and even seepage and leakage occur, which seriously threaten the driving safety of high-speed railways and restrict the rapid development of railway transportation.

[0027] In order to solve the above technical problems, the concrete for the tunnel annular lining structure provided by the embodiment of the present invention comprises 246 parts by weight of cement, 160 parts by weight of water, 78 parts by weight of mineral powder, 77 parts by weight of fly ash, 753 parts by weight to 801 parts by weight of sand, 978 parts by weight to 1026 parts by weight of crushed stone, 4.63 parts by weight to 4.81 parts by weight of water reducing agent, and 20 parts by weight of expansion agent. The concrete for the tunnel annular lining structure of the present invention has advantages in early strength, durability, impermeability and crack resistance through the interaction between various materials in the formula, thereby improving the service life of the tunnel structure.

[0028] In addition, the method for preparing concrete provided by the embodiment of the present invention is simple and easy to operate.

[0029] In addition, the concrete construction method provided by the embodiment of the present invention can complete the pouring of lining structure concrete under the conditions of narrow space and multiple working surfaces, avoiding defects such as cold joints, color difference, cracks, and voids on the surface of the lining structure concrete.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] The raw materials, equipment, etc. used in the preparation process of the concrete for the tunnel annular lining structure described in the embodiment of the present invention are all commercially available and can be purchased on the market.

[0032] An embodiment of the present invention provides concrete for a tunnel annular lining structure, wherein the concrete for a tunnel annular lining structure includes: 246 parts by weight of cement, 160 parts by weight of water, 78 parts by weight of mineral powder, 77 parts by weight of fly ash, 753 parts by weight to 801 parts by weight of sand, 978 parts by weight to 1026 parts by weight of crushed stone, 4.63 parts by weight to 4.81 parts by weight of a water reducer, and 20 parts by weight of an expansion agent.

[0033] Optionally, in some embodiments, the cement is ordinary Portland cement with a strength of 42.5, and the ordinary Portland cement includes tricalcium silicate, dicalcium silicate, and tricalcium aluminate, and the weight ratio of the tricalcium silicate, dicalcium silicate, and tricalcium aluminate is 6:3:1. It should be noted that the strength classification of the ordinary Portland cement of 42.5 can refer to the standards GB / T18046-2017 "Granulated blast furnace slag powder for cement, mortar and concrete" and GB / T 20491-2017 "Steel slag powder for cement and concrete", which will not be repeated here. In addition, when the cement adopts ordinary Portland cement of 42.5, and the effective ingredients in the cement are tricalcium silicate, dicalcium silicate and tricalcium aluminate, the hydrated calcium silicate and hydrated calcium aluminate formed by the hydration reaction with water provide a source of strength for the concrete.

[0034] Optionally, in some embodiments, the type of mineral powder is S95, and the activity index of the mineral powder is greater than 95. It should be noted that the activity index of the mineral powder refers to the mixing of mineral powder and cement in a ratio of 1:1, making standard test pieces according to the cement mortar molding method, and curing according to the standard method. At the same time, standard test pieces of the cement used are also made and cured in a standard manner, and their strengths are measured at the ages of 7d and 28d, respectively. The ratio of the strength of the test piece with mineral powder added to the strength of the cement test piece at the same age is the activity index. S95 means that the 28d activity index reaches 95% or more, that is, the ratio of the mortar strength with 50% mineral powder added to the mortar strength without mineral powder added is not less than 95%.

[0035] Optionally, in some embodiments, the fly ash is Class C II, the water requirement ratio of the fly ash is ≤105%, and the stability of the fly ash is ≤5.0mm. It should be noted that the classification of the fly ash can refer to GB / T1596-1979 "Fly ash used in cement and concrete", which will not be repeated here. The water requirement ratio refers to the amount of water required for the mixture of fly ash and water to reach a certain fluidity, and the stability refers to the ability of fly ash to maintain stable physical and chemical properties under specific conditions.

[0036] It should be noted that selecting mineral powder with specification S95 and activity index >95%; fly ash of Class C II, water requirement ratio ≤105%, and stability ≤5.0mm can reduce the release of cement hydration heat to control the temperature cracks generated during the concrete forming process and play a certain anti-cracking role.

[0037] Optionally, in some embodiments, the fineness modulus of the sand is between 2.3-3.0, the mud content of the sand is ≤2.0wt%, the mud block content of the sand is ≤1.0wt%, and the sand comprises natural river sand or lake sand with a chloride ion content of ≤0.002wt%. Among them, natural river sand or lake sand with a fineness modulus between 2.3-3.0, a mud content of ≤2.0%, a mud block content of ≤1.0%, and a chloride ion content of ≤0.002% is selected to better fill the voids, control cracking during the concrete molding process, and improve its workability and fluidity.

[0038] Optionally, in some embodiments, the crushed stone is a stone with a particle size of 5mm-25mm, the content of needle-like particles in the crushed stone is less than 5wt%, the mud content in the crushed stone is less than 0.8wt%, and the content of mud blocks in the crushed stone is less than 0.5wt%; wherein, the crushed stone includes 308 parts by weight of stones with a particle size of 5-16mm and 718 parts by weight of stones with a particle size of 16-25mm, or the crushed stone includes 293 parts by weight of stones with a particle size of 5mm-16mm and 685 parts by weight of stones with a particle size of 16mm-25mm. It should be noted that the required needle-like particles are particles whose length is greater than 2.4 times the average particle size of the particle grade to which the particle belongs, which are called needle-like particles, and particles whose thickness is less than 0.4 times the average particle size are called flake particles. For details, please refer to GJ 52-2006 "Standards for Quality and Inspection Methods of Sand and Stone for Ordinary Concrete".

[0039] Optionally, in some embodiments, the water reducer is a polycarboxylate high-efficiency water reducer, and the polycarboxylate high-efficiency water reducer includes 20wt%-30wt% of modified phosphate. Wherein, a polycarboxylate water reducer is selected as an admixture, wherein 20%-30% of modified phosphate is contained as a retarding component, and the modified phosphate reacts with calcium hydroxide in the clinker to form insoluble calcium phosphate on the surface of the clinker, thereby extending the setting time of the concrete, enhancing the concrete collapse-preserving effect, extending the effective working time, ensuring the fluidity of the concrete under long-term lining pouring, and avoiding the situation of the vault being hollowed out and not dense; at the same time, the early strength is ensured according to the mix ratio of the cementitious material, and the firmness of the tunnel lining structure is increased; the retarding component can be adjusted within the range of 20wt%-30wt% according to demand.

[0040] Optionally, in some embodiments, the weight of the 20wt%-30wt% modified phosphate is 1.2% of the sum of the weight parts of the cement, fly ash and mineral powder. Cement, fly ash and mineral powder are cementitious materials in the concrete of the present invention. The amount of cement, mineral powder and fly ash in the present invention is 401 parts by weight, and the water-cement ratio is 0.40.

[0041] Optionally, in some embodiments, the expansion agent is one or more of gypsum, lime, and aluminum powder. In the embodiment of the present invention, one or more of gypsum, lime, and aluminum powder are selected as expansion agents to compensate for the shrinkage of concrete, improve the crack resistance and impermeability, effectively avoid water seepage and block falling caused by cracks caused by self-shrinkage, improve the engineering quality of the construction structure, extend the life of the structure, and reduce the subsequent maintenance cost.

[0042] In addition, an embodiment of the present invention further provides a method for preparing concrete, which is used to prepare the concrete for the tunnel annular lining structure as described above, and the method comprises: uniformly mixing cement, mineral powder, fly ash, and expansion agent according to the formula for 30 seconds, then adding sand and crushed stone and stirring for 30 seconds, and after the dry materials are uniformly mixed, adding water and water reducing agent and stirring for 1 minute to obtain the concrete for the tunnel annular lining structure. The preparation method is simple and easy to operate.

[0043] In addition, an embodiment of the present invention further provides a concrete construction method, which is used to cast the concrete for the tunnel annular lining structure on site, and the construction method includes:

[0044] a. Pour the concrete symmetrically in layers from bottom to top, with each layer pouring height less than or equal to 30 cm, and fully vibrate with an attached plate vibrator and a manual insertion vibrator;

[0045] b. The pouring sequence of each layer should start from the end where the concrete has been constructed to ensure the joint quality of the concrete construction joint and facilitate exhaust;

[0046] c. Remove the mold after 24-36 hours. After the mold is removed, the concrete should be cured immediately. Use special personnel to sprinkle water. The curing time is greater than or equal to 14 days;

[0047] d. When lining the arch wall, first retract the side walls on both sides to the middle, and then slowly lower the trolley to prevent the side walls from sticking to the mold. After demolding is completed, clean the template with a high-pressure water gun and apply demolding oil for the next cycle.

[0048] The concrete construction method provided by the embodiment of the present invention can complete the pouring of lining structure concrete under the conditions of narrow space and multiple working surfaces, and avoid defects such as cold joints, color differences, cracks, and voids on the surface of the lining structure concrete.

[0049] The concrete for the tunnel annular lining structure and the preparation method thereof provided in the embodiments of the present invention are specifically described below through Examples 1 and 2.

[0050] Example 1

[0051] 1. Concrete for tunnel ring lining structure and its preparation

[0052] (1) Formulation

[0053] The concrete used for the tunnel annular lining structure in this embodiment includes:

[0054] 246Kg of 42.5PO ordinary Portland cement, 160Kg of water, 78Kg of S95 mineral powder, 77Kg of Class C II fly ash, 753Kg of sand with fineness modulus 2.5, 308Kg of 5mm-16mm gravel, 718Kg of 16mm-25mm gravel, 4.63Kg of polycarboxylate water-reducing agent containing 20wt% of modified phosphate, and 20Kg of gypsum aluminum powder expansion agent.

[0055] Among them, ordinary silicate cement includes tricalcium silicate, dicalcium silicate and tricalcium aluminate, and the weight ratio of tricalcium silicate, dicalcium silicate and tricalcium aluminate is 6:3:1. The activity index of mineral powder is greater than 95. The water requirement ratio of fly ash is ≤105%, and the stability of fly ash is ≤5.0mm. The mud content of sand is ≤2.0wt%, the mud content of sand is ≤1.0wt%, and the sand includes natural river sand with a chloride ion content of ≤0.002wt%. The weight of 20wt% modified phosphate is 1.2% of the sum of the weight parts of cement, fly ash and mineral powder.

[0056] (2) Preparation method

[0057] First, ordinary Portland cement, S95 mineral powder, Class C II fly ash, and gypsum aluminum powder expansion agent are evenly mixed and stirred for 30 seconds, and then sand and gravel are added and stirred for 30 seconds. After the dry materials are evenly mixed, water and water reducing agent are added and stirred for 1 minute to obtain concrete products.

[0058] (3) Performance testing

[0059] The prepared concrete products were subjected to relevant performance tests, and the test results are shown in Tables 1 and 2.

[0060] Table 1 Performance indicators in Example 1

[0061]

[0062] Table 2 Slump index in Example 1

[0063]

[0064] Example 2

[0065] 1. Concrete for tunnel ring lining structure and its preparation

[0066] (1) Formulation

[0067] The concrete used for the tunnel annular lining structure in this embodiment includes:

[0068] 246Kg of 42.5PO ordinary Portland cement, 160Kg of water, 78Kg of S95 mineral powder, 77Kg of Class C II fly ash, 801Kg of sand with fineness modulus 2.6, 293Kg of 5-16mm crushed stone, 685Kg of 16-25mm crushed stone, 4.81Kg of polycarboxylate water reducer containing 25wt% of modified phosphate, and 20Kg of gypsum aluminum powder expansion agent.

[0069] Among them, ordinary silicate cement includes tricalcium silicate, dicalcium silicate and tricalcium aluminate, and the weight ratio of tricalcium silicate, dicalcium silicate and tricalcium aluminate is 6:3:1. The activity index of mineral powder is greater than 95. The water requirement ratio of fly ash is ≤105%, and the stability of fly ash is ≤5.0mm. The mud content of sand is ≤2.0wt%, the mud content of sand is ≤1.0wt%, and the sand includes natural river sand with a chloride ion content of ≤0.002wt%. The weight of 25wt%-modified phosphate is 1.2% of the sum of the weight of cement, fly ash and mineral powder.

[0070] (2) Preparation method

[0071] First, ordinary Portland cement, S95 mineral powder, Class C II fly ash, and gypsum aluminum powder expansion agent are evenly mixed and stirred for 30 seconds, and then sand and gravel are added and stirred for 30 seconds. After the dry materials are evenly mixed, water and water reducing agent are added and stirred for 1 minute to obtain concrete products.

[0072] (3) Performance testing

[0073] The prepared concrete products were subjected to relevant performance tests, and the test results are shown in Tables 3 and 4.

[0074] Table 3 Performance indicators in Example 2

[0075]

[0076] Table 4 Slump index in Example 2

[0077]

[0078] Comparative Example 1

[0079] The difference between this comparative example 1 and examples 1 and 2 is that the formula composition is different. In particular, the water reducing agent used in this comparative example 1 is different from that in examples 1 and 2, and this comparative example 1 does not contain an expansion agent and does not contain 20wt%-30wt% of modified phosphate.

[0080] (1) Formulation

[0081] 216Kg of 42.5PO ordinary Portland cement, 155Kg of water, 52Kg of S95 mineral powder, 82Kg of Class C II fly ash, 775Kg of sand with fineness modulus 2.8, 1028Kg of 5mm-25mm crushed stone, and 3.14Kg of polycarboxylic acid water reducer.

[0082] (2) Preparation method

[0083] First, ordinary Portland cement, S95 mineral powder, and Class C II fly ash are evenly mixed and stirred for 30 seconds, and then sand and gravel are added and stirred for 30 seconds. After the dry materials are evenly mixed, water and polycarboxylate water reducer are added and stirred for 1 minute to obtain concrete products.

[0084] (3) Performance testing

[0085] The prepared concrete products were subjected to relevant performance tests, and the test results are shown in Tables 5 and 6.

[0086] Table 5 Performance indicators in comparative example 1

[0087]

[0088] Table 6 Slump index of comparative example 1

[0089]

[0090]

[0091] As can be seen from Table 1 to Table 6, the concrete for the annular lining structure of the tunnel provided by Examples 1 and 2 of the present invention has a slump of ≥200mm within 1 hour, an expansion of ≥400mm, an initial setting time of 8-10h, a final setting time of 12-14h, a working performance retention time of 4h, a 3d compressive strength of ≥35.0MPa, and an electric flux of ≤1200C; and the preparation is simple, which can meet the long-term construction requirements of the tunnel. Compared with Examples 1 and 2, the slump of Comparative Example 1 is higher than that of Examples 1 and 2, and the concrete product prepared in Comparative Example 1 has a higher collapse loss and cannot meet the performance requirements of long-term construction, which is easy to cause a decrease in structural performance, an increase in construction difficulty, and a shortened lifespan.

[0092] Effect Example 1 In this effect example, the concrete of Example 2 and Comparative Example 1 were poured on site, and the subsequent molding effect was as follows: Figure 1 As shown, compared with the comparative example 1, the concrete of Example 2 has no obvious cracking marks in its molding effect.

[0093] In this effect example, the concrete of Example 2 and Comparative Example 1 were respectively cast on site. In terms of the later forming effect, as shown in FIG. 2 , the concrete of Example 2 had no obvious cracking marks compared with the concrete of Comparative Example 1.

[0094] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A concrete for a tunnel annular lining structure, characterized in that: The concrete for the tunnel annular lining structure comprises: 246 parts by weight of cement, 160 parts by weight of water, 78 parts by weight of mineral powder, 77 parts by weight of fly ash, 753 to 801 parts by weight of sand, 978 to 1026 parts by weight of crushed stone, 4.63 to 4.81 parts by weight of water reducing agent, and 20 parts by weight of expansion agent.

2. The concrete for the tunnel annular lining structure according to claim 1, characterized in that: The cement is ordinary Portland cement with a strength of 42.5, and the ordinary Portland cement includes tricalcium silicate, dicalcium silicate, and tricalcium aluminate, and the weight ratio of the tricalcium silicate, dicalcium silicate, and tricalcium aluminate is 6:3:

1.

3. The concrete for the tunnel annular lining structure according to claim 1, characterized in that: The type of the mineral powder is S95, and the activity index of the mineral powder is greater than 95.

4. The concrete for the tunnel annular lining structure according to claim 1, characterized in that: The fly ash is of Class C II, the water requirement ratio of the fly ash is ≤105%, and the stability of the fly ash is ≤5.0mm.

5. The concrete for tunnel annular lining structure according to claim 1, characterized in that: The fineness modulus of the sand is between 2.3 and 3.0, the mud content of the sand is ≤2.0wt%, the mud block content of the sand is ≤1.0wt%, and the sand includes natural river sand or lake sand with a chloride ion content of ≤0.002wt%.

6. The concrete for tunnel annular lining structure according to claim 1, characterized in that: The crushed stone is gravel with a particle size of 5mm-25mm, the content of needle-like particles in the crushed stone is less than 5wt%, the mud content in the crushed stone is less than 0.8wt%, and the mud block content in the crushed stone is less than 0.5wt%; wherein, the crushed stone includes 308 parts by weight of gravel with a particle size of 5mm-16mm and 718 parts by weight of gravel with a particle size of 16mm-25mm, or the crushed stone includes 293 parts by weight of gravel with a particle size of 5mm-16mm and 685 parts by weight of gravel with a particle size of 16mm-25mm.

7. The concrete for the tunnel annular lining structure according to claim 1, characterized in that: The water reducer is a polycarboxylic acid high-efficiency water reducer, and the polycarboxylic acid high-efficiency water reducer comprises 20wt%-30wt% of modified phosphate.

8. The concrete for the tunnel annular lining structure according to claim 7, characterized in that: The weight of the 20wt%-30wt% modified phosphate is 1.2% of the total weight of the cement, fly ash and mineral powder.

9. The concrete for the tunnel annular lining structure according to claim 1, characterized in that: The expansion agent is one or more of gypsum, lime and aluminum powder.

10. A method for preparing concrete, characterized in that: The preparation method is used to prepare the concrete for the tunnel annular lining structure according to any one of claims 1 to 9, and the preparation method comprises: According to the formula, cement, mineral powder, fly ash and expansion agent are uniformly mixed and stirred for 30 seconds, then sand and crushed stone are added and stirred for 30 seconds, and after the dry materials are evenly mixed, water and water reducing agent are added and stirred for 1 minute to obtain the concrete for the tunnel annular lining structure.

11. A method for constructing concrete, characterized in that: The construction method is used to cast on-site the concrete for the tunnel annular lining structure according to any one of claims 1 to 9, and the construction method comprises: a. Pour the concrete symmetrically in layers from bottom to top, with each layer pouring height less than or equal to 30 cm, and fully vibrate with an attached plate vibrator and a manual insertion vibrator; b. The pouring sequence of each layer should start from the end where the concrete has been constructed to ensure the joint quality of the concrete construction joint and facilitate exhaust; c. Remove the mold after 24-36 hours. After the mold is removed, the concrete should be cured immediately. Use special personnel to sprinkle water. The curing time is greater than or equal to 14 days; d. When lining the arch wall, first retract the side walls on both sides to the middle, and then slowly lower the trolley to prevent the side walls from sticking to the mold. After demolding is completed, clean the template with a high-pressure water gun and apply demolding oil for the next cycle.

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