Tunnel inverted arch, inverted arch filled early strength slurry bone polymeric concrete and construction method

Abstract

The invention provides a tunnel inverted arch, inverted arch filling early strength slurry bone polymeric concrete and a construction method, and relates to the technical field of tunnel inverted arches, inverted arch filling concrete materials and construction methods. The early-strength slurry bone polymer concrete is formed by injecting an early-strength grouting material into aggregate, the design strength can be achieved within 12 h, and continuous excavation construction of the tunnel is achieved; the aggregate of the inverted arch is 9.5-20 mm, the aggregate of the filling layer is 4.75-31.5 mm coarse aggregate, the aggregate is densely piled in advance, the proportion of the aggregate is large, the shrinkage of the slurry is restrained, and the cooperative development of strength and elastic modulus is facilitated; the early-strength grouting material contains preferable industrial sand and a reasonable dosage of retarder, high strength and high fluidity are achieved, the retarding time meeting the pouring duration is met, the slurry proportion is small, shrinkage is small, the cracking risk is small, and durability is better; during construction, the aggregate is taken and filled nearby, the slurry is prepared and poured nearby, film covering and curing are conducted in time, pure slurry flows fast, consumed time is short, vibration is not needed, the delayed coagulation duration allowance is enough, the initial coagulation risk is small, the management difficulty is small, the forming quality is good, cost is low, and the popularization value is high.

Description

Technical Field

[0001] This invention relates to the technical field of building materials and construction methods, and particularly to the technical field of tunnel invert arches and invert arch filling concrete materials and construction methods. Specifically, it relates to a tunnel invert arch and invert arch filling early-strength grout aggregate polymer concrete and construction method. Background Technology

[0002] The tunnel invert is a reverse arch structure installed at the bottom of the tunnel to improve the stress conditions of the superstructure. It is one of the main components of the tunnel structure. On the one hand, it effectively transfers the ground pressure above the tunnel to the underground through the tunnel sidewall structure or the load from the road surface. On the other hand, it effectively resists the reaction force from the strata below the tunnel and forms an integral part of the tunnel with the secondary lining, increasing structural stability. The tunnel invert infill refers to the middle part above the tunnel invert and below the road surface structure, which serves to fill to the required elevation and transfer the road surface load downwards.

[0003] The existing construction process for tunnel invert and invert filling is as follows: construction preparation → excavation and foundation treatment of tunnel invert layer → initial support and waterproofing layer laying of tunnel invert layer → reinforcement binding and formwork installation of tunnel invert layer → concrete pouring and vibration of tunnel invert layer → demolding of tunnel invert concrete when it reaches the design strength → formwork erection of tunnel invert filling layer → concrete pouring of tunnel invert filling layer → curing of tunnel invert filling concrete to the design strength → opening to traffic.

[0004] In existing technologies, the construction of cast-in-place tunnel inverts and their filling concrete involves complex procedures and a long curing period. Furthermore, the invert concrete requires meticulous vibration. To enable continuous tunnel excavation, invert trestle bridges are typically used, allowing muck trucks to pass above while the tunnel invert is constructed below, ensuring no interference between the two processes. However, invert trestle bridges are expensive, their movement is complex, and their location above the under-construction invert restricts operational space and makes quality control difficult. Although attempts have been made to shorten the curing period and open traffic sooner by adding early-strength admixtures, these methods generally suffer from slow early strength development, poor fluidity, high costs, and poor molding quality. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of slow early strength development and unstable workability of concrete, complex construction procedures and long curing period in existing materials and construction methods for tunnel inverts and invert filling concrete. The invention proposes a tunnel invert and invert filling early-strength grout-aggregate polymer concrete and construction method.

[0006] To achieve the above-mentioned objectives, the present invention provides a tunnel invert and an invert-filled early-strength grout aggregate polymer concrete, 1. comprising the following raw materials by volume: 58-60 parts of aggregate, 40-42 parts of early-strength grout; In the aforementioned early-strength aggregate polymer concrete, the strength grade of the tunnel invert arch portion shall not be lower than C25, and the strength grade of the tunnel invert arch filling portion shall not be lower than C15. The preparation method of the early-strength grout-aggregate polymer concrete is as follows: the early-strength grout is injected into the pre-stacked aggregate to wrap the aggregate and fill the voids in the aggregate, and then cured to form the concrete. The aggregate includes coarse aggregates of three particle sizes: 4.75–9.5 mm, 9.5–20 mm, and 16–31.5 mm; the ratio of the parent rock compressive strength of the coarse aggregate to the design compressive strength of the concrete is not less than 1.5. The 12h, 28d, and 60d compressive strength of the early-strength grouting material shall not be lower than the 12h, 28d, and 60d design compressive strength of the corresponding early-strength grout-aggregate polymer concrete. The early-strength slurry per cubic meter comprises the following raw materials: Sulfoaluminate cement 500-600kg, Class F II fly ash 400-500kg, industrial sand 600-800kg, water 400-450kg, water-reducing agent 10.8-19.8kg, retarder 0.18-0.66kg; The total binder of the early-strength grouting material includes sulfoaluminate cement and Class F II fly ash, and the mass of the total binder is 900-1100 kg / m³. The water-cement ratio of the early-strength grout is 0.36-0.5; The industrial sand has a particle size of 0.075-2.36 mm, a fineness modulus of no more than 1.8, a porosity of 20-30%, a water absorption rate of 0.8-5.0%, and a silica content of 30-45%.

[0007] The technical solution of this invention addresses the different mechanical performance requirements of the tunnel invert (the main load-bearing structure) and the invert infill (the main force-transmitting structural layer), designing aggregates and early-strength grouting materials separately, making the material design more targeted and scientific. Both the tunnel invert and invert infill utilize early-strength grouting materials, which exhibit rapid early strength development, short curing periods, and earlier traffic opening times. This eliminates the need for equipment such as invert trestle bridges, reducing procedures and making the process convenient and efficient.

[0008] This invention utilizes industrial sand, specifically screened for use as fine aggregate in early-strength grouting materials. The industrial sand refers to industrial waste materials used undisturbed or processed that can replace natural river sand or manufactured sand, offering advantages such as low cost, wide availability, and solid waste resource utilization. By controlling the particle size, fineness modulus, and specific surface area of ​​the industrial sand, the proportion of reactive micro-fine aggregates in the industrial sand is increased. On one hand, the high silica content (30% or more) and large specific surface area of ​​the industrial sand can promote the reaction with calcium hydroxide during cement hydration, producing calcium silicate gel and enhancing the strength and durability of the early-strength grouting material. On the other hand, the small particle size and strong adsorption capacity of the industrial sand allow for more thorough contact with cement and other cementitious materials, resulting in more and more intense chemical reactions, thus promoting faster early strength development.

[0009] Industrial sand has no sharp edges and obvious ball bearing effect, which can increase the flowability of early-strength grout and ensure the density of early-strength grout filling in the aggregate; its porous surface can store moisture, providing sufficient moisture for later internal curing, further reducing the drying shrinkage of early-strength grout and reducing the risk of cracking of tunnel invert and invert filling.

[0010] Among them, Class F II fly ash is preferred, as it can better control the shrinkage of early-strength grout, improve fluidity, and optimize material costs.

[0011] Preferably, the water-reducing agent is a comb-structured polycarboxylate-based water-reducing agent with a water reduction rate of not less than 25%, and the dosage of the water-reducing agent accounts for 1.2-1.8% of the total binder mass. The comb-structured polycarboxylate-based water-reducing agent has a high water reduction rate and excellent dispersion stability, enabling it to impart excellent flowability and long-term workability retention to early-strength grouting materials at a low water-cement ratio. This is one of the key factors enabling early-strength grouting materials to achieve self-leveling and fully penetrate and fill aggregate voids. Its dosage range has been optimized to achieve the best water reduction effect while avoiding serious problems such as segregation and industrial sand settling due to excessive addition.

[0012] Preferably, the retarder comprises a carbohydrate retarder and a hydroxycarboxylic acid retarder, with a mass ratio of 1:1.5-2.5, and the retarder dosage accounts for 0.2-0.6‰ of the total binder mass. The carbohydrate retarder includes glucose, fructose, and sucrose; the hydroxycarboxylic acid retarder includes tartaric acid and its salts, citric acid and its salts, and gluconic acid and its salts. The addition of the retarder can prolong the slump retention time of the early-strength grout, maintain its workable state, reduce the hydration heat release rate, and lower the risk of cracking due to concentrated heat release. Using a composite retarder of carbohydrates and hydroxycarboxylic acids allows for a more stable and controllable regulation of the hydration process of sulfoaluminate cement by utilizing the synergistic effect of different retarding mechanisms.

[0013] Preferably, the working performance of the early-strength grout is as follows: the initial flow cone time is not greater than 18s, the 2h flow cone time is not greater than 35s; the initial truncated cone flowability is not less than 400mm, and the 2h truncated cone flowability is not less than 350mm.

[0014] Preferably, the 28-day shrinkage expansion rate of the early-strength grout satisfies the formula: (δ △ +δ v )+δ c ≤r; where r is the design value of the 28-day shrinkage and expansion rate of the tunnel invert or the early-strength aggregate polymer concrete filling the invert; δ △ The design value for the expansion rate of early-strength grouting material; δ v δ represents the design value for shrinkage constraint of coarse aggregate on early-strength grout; c This is the design value for the shrinkage rate of early-strength grouting material.

[0015] Furthermore, to achieve the above-mentioned objectives, this invention provides a construction method for a tunnel invert and the early-strength aggregate polymer concrete filling for the invert, comprising the following steps: Step 1: Tie the reinforcing steel bars of the tunnel invert layer and construct the overall formwork for the tunnel invert layer; Step 2: Fill the openings in the tunnel invert arch formwork with the first aggregate, which is filled by free stacking. Step 3: After the first aggregate is filled, pour early-strength grout into the first aggregate through the opening in the template; Step 4: After the early-strength grouting material for the tunnel invert layer is poured, immediately cover it with a thick plastic film for moisture retention and curing; after the strength is not less than 75% of the design strength, remove the formwork, cover it with a thick plastic film for continued moisture retention and curing, until the next construction process is carried out. Step 5: Erect the formwork for the tunnel invert arch filling layer; Step 6: Fill the tunnel invert arch filling layer template with the second aggregate. The second aggregate is filled by free stacking. Step 7: After the second aggregate is filled, pour early-strength grout into the second aggregate; Step 8: After the early-strength grouting material for the tunnel invert arch filling layer is poured, immediately cover the top surface with a thick plastic film for moisture retention and curing; after the strength reaches the design requirements, remove the formwork and cover with a thick plastic film to continue moisture retention and curing for at least 3 days.

[0016] This method is highly compatible with material properties. The "aggregate first, then early-strength grout" construction process avoids problems such as segregation, bleeding, and pipe blockage that may occur in traditional concrete pouring from the source. It also eliminates the need for vibration, is simple in process, has low equipment investment, and produces high-quality results, making it particularly suitable for construction in confined spaces within tunnels. The "pour and cure simultaneously" method ensures that the early-strength grout has sufficient moisture for full reaction during strength development, while reducing the risk of dehydration, drying, and shrinkage cracking. This construction method avoids the traditional method of monolithic mixing, transportation, and pouring of concrete. It eliminates the need for large-scale mixing plants and the need for repeated transportation by concrete mixer trucks. Only a small-scale grouting machine is needed locally to prepare the early-strength grout, saving transportation time and solving the problem of time loss during transportation that is unavoidable with traditional early-strength concrete (traditional early-strength concrete has a fast reaction rate, is prone to initial setting during transportation, and is difficult to release from the mixer truck, so it is rarely used in actual construction).

[0017] Preferably, in step 2, the first aggregate in the tunnel invert layer is coarse aggregate with a particle size of 9.5-20mm.

[0018] The first aggregate in the tunnel invert layer is coarse aggregate with a particle size of 9.5-20mm. This is done for two reasons: first, to control the maximum particle size of the aggregate and ensure that it can pass smoothly through the gaps in the steel mesh; and second, because the coarse aggregate of 9.5-20mm forms a porosity of about 41-43% (confidence level 95%), the relatively larger porosity allows for the pouring of more early-strength grout, which helps to improve the structural strength.

[0019] Preferably, in step 6, the second aggregate in the tunnel invert filling layer is coarse aggregate with a particle size of 4.75-9.5:9.5-20:16-31.5mm, forming a gradation of 1:5:4, 1:6:3, or 1:3:6.

[0020] The second aggregate in the tunnel invert filling layer is selected as coarse aggregate with a particle size of 4.75-9.5: 9.5-20: 16-31.5mm, forming a gradation of 1:5:4, or 1:6:3, or 1:3:6, resulting in a porosity of approximately 40-41.5% (confidence level 95%). The relatively smaller porosity allows for the use of less expensive early-strength grouting material, saving material costs while meeting strength requirements.

[0021] Preferably, in steps 3 and 7, the early-strength grout is injected by direct pouring or by filling from the bottom up using a conduit.

[0022] Preferably, in steps 4 and 8, within 5 minutes after the early-strength grout is injected, a 0.08-0.15mm thick plastic film is applied to cover the entire cross-section for moisture retention and curing. By limiting the covering time and film thickness, moisture evaporation can be prevented in a timely and effective manner.

[0023] Preferably, if the truncated cone flowability of the early-strength grout is less than 350mm, pouring should be stopped immediately. During construction, the longitudinal length of the pouring section should be controlled according to the duration of performance maintenance to avoid loss of performance leading to incomplete filling.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. An early-strength grouting material was invented to inject aggregate to form early-strength grout-aggregate polymer concrete for tunnel invert and invert filling layer, achieving rapid early strength development, short curing period, and early opening to traffic. It eliminates the need for equipment such as invert trestle bridges, reduces procedures, and is convenient and efficient. 2. The construction method of "pile aggregate first, then inject early-strength grout" avoids the problems of segregation, bleeding, and pipe blockage that occur during long-term transportation and construction of traditional concrete coarse and fine aggregates and cementitious materials through overall mixing, transportation, and pouring. It improves the quality of structural forming, eliminates the need for large-scale mixing plants and the need for repeated transportation of concrete mixer trucks, and only requires the preparation of early-strength grout using a small slurry making machine nearby, saving transportation time and solving the problem of time loss caused by transportation that is unavoidable in traditional early-strength concrete. 3. Early-strength grout-aggregate polymer concrete has a higher proportion of aggregates compared to traditional concrete, which fully utilizes the role of the aggregate skeleton, further constrains the drying shrinkage of the early-strength grout, and reduces the risk of cracking. 4. The transportation cost of coarse aggregate in concrete accounts for about 25% of the concrete cost. This invention can use local materials and nearby materials, saving the cost of transporting coarse aggregate back and forth. 5. This production method saves energy, generates less dust, requires no manual vibration, and reduces carbon emissions by approximately 25%. Detailed Implementation

[0025] To more clearly describe the inventive objectives, technical solutions, and advantages of the specific embodiments of this invention, the solutions in the specific embodiments will be described in detail below. The specific technical solutions involved in the following specific embodiments are merely for the purpose of clearly and completely describing the innovative technical solutions of this invention. They are only a part of the specific implementation methods that this invention can adopt, not all the embodiments, and should not be construed as limiting the innovative solutions of this invention. Any solution that adopts the same inventive concept as this invention should be included within the protection scope of this invention.

[0026] For those skilled in the art, when understanding the solutions described in the specific embodiments of the present invention, conventional technical manuals in the field can be consulted. At the same time, appropriate understandings or adjustments can be made to the above-mentioned terms to deduce the same or similar technical solutions without creative effort.

[0027] To examine the superior performance of the tunnel invert and the early-strength aggregate-polymer concrete filling obtained by the technical solution of this invention, the following formula adjustments were made, and performance comparisons were conducted through experiments, as well as material costs were calculated. In each embodiment, the early-strength grout used in the tunnel invert and the early-strength aggregate-polymer concrete filling uses the same formula; however, the formulas of the early-strength grout differ in different embodiments. Furthermore, based on the actual strength requirements of the tunnel invert and the filling, different formulas of early-strength grout can be used for the two structural components to further reduce raw material costs.

[0028] Example 1 An early-strength aggregate-polymer concrete for tunnel inverts and invert fillings comprises the following raw materials by volume: C25 Tunnel Invert: 59 parts aggregate, 41 parts early strength grout, aggregate particle size 9.5-20mm, parent rock compressive strength ≥37.5MPa; C15 tunnel invert filling: 59 parts aggregate, 41 parts early strength grout, aggregate particle size ratio of 4.75-9.5mm: 9.5-20mm: 16-31.5mm = 1:5:4, aggregate parent rock compressive strength ≥22.5MPa; Each cubic meter of the early-strength grout is composed of the following raw materials mixed together: 550 kg of sulfoaluminate cement, 450 kg of fly ash (secondary fly ash), 700 kg of industrial sand (particle size 0.075-2.36 mm, fineness modulus 1.6, porosity 25%, water absorption 2%, silica content 40%), 15 kg of water-reducing agent (polyester-type polycarboxylate water-reducing agent), 425 kg of water, and 0.42 kg of retarder (T:QJSS ratio 1:2). In this embodiment, the total adhesive content is 1000 kg (cement + fly ash). The water-cement ratio is 0.43; the water-reducing agent dosage is 1.5%; and the retarder dosage is 0.42‰. The density of the early-strength grout is 2155 kg / m³; the density of the C25 early-strength grout aggregate polymer concrete for the tunnel invert is 2380 kg / m³; and the density of the C15 early-strength grout aggregate polymer concrete for filling the tunnel invert is 2380 kg / m³.

[0029] Example 2 An early-strength aggregate-polymer concrete for tunnel inverts and invert fillings comprises the following raw materials by volume: C25 Tunnel Invert: 59 parts aggregate, 41 parts early strength grout, aggregate particle size 9.5-20mm, parent rock compressive strength ≥37.5MPa; C15 tunnel invert filling: 58 parts aggregate, 42 parts early strength grout, aggregate particle size ratio of 4.75-9.5mm: 9.5-20mm: 16-31.5mm = 1:6:3, aggregate parent rock compressive strength ≥22.5MPa; Each cubic meter of the early-strength grout is composed of the following raw materials mixed together: 550 kg of sulfoaluminate cement, 450 kg of fly ash (secondary fly ash), 700 kg of industrial sand (particle size 0.075-2.36 mm, fineness modulus 1.6, porosity 25%, water absorption 2%, silica content 40%), 15 kg of water-reducing agent (polyester-type polycarboxylate water-reducing agent), 425 kg of water, and 0.42 kg of retarder (T:QJSS ratio 1:2). In this embodiment, the total adhesive content is 1000 kg (cement + fly ash). The water-cement ratio is 0.43; the water-reducing agent dosage is 1.5%; and the retarder dosage is 0.42‰. The density of the early-strength grout is 2155 kg / m³; the density of the C25 early-strength grout aggregate polymer concrete for the tunnel invert is 2380 kg / m³; and the density of the C15 early-strength grout aggregate polymer concrete for filling the tunnel invert is 2385 kg / m³.

[0030] Example 3 An early-strength aggregate-polymer concrete for tunnel inverts and invert fillings comprises the following raw materials by volume: C25 Tunnel Invert: 59 parts aggregate, 41 parts early strength grout, aggregate particle size 9.5-20mm, parent rock compressive strength ≥37.5MPa; C15 tunnel invert filling: 60 parts aggregate, 40 parts early strength grout, aggregate particle size ratio of 4.75-9.5mm: 9.5-20mm: 16-31.5mm = 1:3:6, parent rock compressive strength ≥22.5MPa; Each cubic meter of the early-strength grout is composed of the following raw materials mixed together: 550 kg of sulfoaluminate cement, 450 kg of fly ash (secondary fly ash), 700 kg of industrial sand (particle size 0.075-2.36 mm, fineness modulus 1.6, porosity 25%, water absorption 2%, silica content 40%), 15 kg of water-reducing agent (polyester-type polycarboxylate water-reducing agent), 425 kg of water, and 0.42 kg of retarder (T:QJSS ratio 1:2). In this embodiment, the total adhesive content is 1000 kg (cement + fly ash). The water-cement ratio is 0.43; the water-reducing agent dosage is 1.5%; and the retarder dosage is 0.42‰. The density of the early-strength grout is 2155 kg / m³; the density of the C25 early-strength grout aggregate polymer concrete for the tunnel invert is 2380 kg / m³; and the density of the C15 early-strength grout aggregate polymer concrete for filling the tunnel invert is 2340 kg / m³.

[0031] Example 4 An early-strength aggregate-polymer concrete for tunnel inverts and invert fillings comprises the following raw materials by volume: C25 Tunnel Invert: 59 parts aggregate, 41 parts early strength grout, aggregate particle size 9.5-20mm, parent rock compressive strength ≥37.5MPa; C15 tunnel invert filling: 59 parts aggregate, 41 parts early strength grout, aggregate particle size ratio of 4.75-9.5mm: 9.5-20mm: 16-31.5mm = 1:5:4, aggregate parent rock compressive strength ≥22.5MPa; Each cubic meter of the early-strength grout is composed of the following raw materials mixed together: 500 kg of sulfoaluminate cement, 400 kg of fly ash (secondary fly ash), 800 kg of industrial sand (particle size 0.075-2.36 mm, fineness modulus 1.8, porosity 25%, water absorption 2%, silica content 30%), 12 kg of water-reducing agent (polyester-type polycarboxylate water-reducing agent), 450 kg of water, and 0.52 kg of retarder (T:QJSS ratio 1:1.5). In this embodiment, the total adhesive content is 900 kg (cement + fly ash). The water-cement ratio is 0.5; the water-reducing agent dosage is 1.3%; and the retarder dosage is 0.58‰. The density of the early-strength grout is 2160 kg / m³; the density of the C25 early-strength grout aggregate polymer concrete for the tunnel invert is 2390 kg / m³; and the density of the C15 early-strength grout aggregate polymer concrete for filling the tunnel invert is 2390 kg / m³.

[0032] Example 5 An early-strength aggregate-polymer concrete for tunnel inverts and invert fillings comprises the following raw materials by volume: C25 Tunnel Invert: 59 parts aggregate, 41 parts early strength grout, aggregate particle size 9.5-20mm, parent rock compressive strength ≥37.5MPa; C15 tunnel invert filling: 59 parts aggregate, 41 parts early strength grout, aggregate particle size ratio of 4.75-9.5mm: 9.5-20mm: 16-31.5mm = 1:5:4, aggregate parent rock compressive strength ≥22.5MPa; Each cubic meter of the early-strength grout is composed of the following raw materials mixed together: 600 kg of sulfoaluminate cement, 500 kg of fly ash (secondary fly ash), 600 kg of industrial sand (particle size 0.075-2.36 mm, fineness modulus 1.5, porosity 25%, water absorption 2%, silica content 45%), 18 kg of water-reducing agent (polyester-type polycarboxylate water-reducing agent), 400 kg of water, and 0.35 kg of retarder (T:QJSS ratio 1:2.5). In this embodiment, the total adhesive content is 1100 kg (cement + fly ash). The water-cement ratio is 0.36; the water-reducing agent dosage is 1.6%; and the retarder dosage is 0.32‰. The density of the early-strength grout is 2170 kg / m³; the density of the C25 early-strength grout aggregate polymer concrete for the tunnel invert is 2400 kg / m³; and the density of the C15 early-strength grout aggregate polymer concrete for filling the tunnel invert is 2400 kg / m³.

[0033] Example 6 An early-strength aggregate-polymer concrete for tunnel inverts and invert fillings comprises the following raw materials by volume: C25 Tunnel Invert: 59 parts aggregate, 41 parts early strength grout, aggregate particle size 9.5-20mm, parent rock compressive strength ≥37.5MPa; C15 tunnel invert filling: 59 parts aggregate, 41 parts early strength grout, aggregate particle size ratio of 4.75-9.5mm: 9.5-20mm: 16-31.5mm = 1:5:4, aggregate parent rock compressive strength ≥22.5MPa; Each cubic meter of the early-strength grout is composed of the following raw materials mixed together: 550 kg of sulfoaluminate cement, 450 kg of fly ash (secondary fly ash), 700 kg of manufactured sand (manufactured sand particle size 0-4.75 mm, fineness modulus 2.7), 15 kg of water-reducing agent (polyester polycarboxylate water-reducing agent), 425 kg of water, and 0.42 kg of retarder (T:QJSS ratio 1:2). In this embodiment, the total adhesive content is 1000 kg (cement + fly ash). The water-cement ratio is 0.43; the water-reducing agent dosage is 1.5%; and the retarder dosage is 0.42‰. The density of the early-strength grout is 2140 kg / m³; the density of the C25 early-strength grout aggregate polymer concrete for the tunnel invert is 2335 kg / m³; and the density of the C15 early-strength grout aggregate polymer concrete for filling the tunnel invert is 2330 kg / m³.

[0034] Comparative Example 1 A type of ordinary concrete for tunnel inverts and invert filling, wherein the strength grade of the tunnel invert concrete is C25 and the strength grade of the tunnel invert filling concrete is C15, and both types of concrete comprise the following raw materials in parts by weight: Each cubic meter of C25 invert concrete comprises the following raw materials by weight: 229 kg of cement, 98 kg of fly ash, 782 kg of manufactured sand (the particle size of the manufactured sand is 0-4.75 mm and the fineness modulus is 2.8), 1176 kg of coarse aggregate, 143 kg of water, and 3.27 kg of high-performance polycarboxylate superplasticizer (polyester-type polycarboxylate superplasticizer with a water reduction rate of more than 25%). In this comparative example, the total adhesive content is 327 kg (cement + fly ash). The water-cement ratio is 0.44; the concrete density is 2400 kg / m³; the initial setting time is 6 hours, the final setting time is 10 hours, there is no strength after 12 hours, the compressive strength after 28 days is 37.4 MPa, and the raw material cost per m³ of concrete is 316.6 yuan.

[0035] The C15 invert arch filling concrete per cubic meter comprises the following raw materials by weight: 195kg of cement, 83kg of fly ash, 968kg of manufactured sand (the particle size of the manufactured sand is 0-4.75mm and the fineness modulus is 2.9), 1008kg of coarse aggregate, 150kg of water, and 2.78kg of high-performance polycarboxylate superplasticizer (polyester-type polycarboxylate superplasticizer with a water reduction rate of more than 25%). In this comparative example, the total adhesive content is 278 kg (cement + fly ash). The water-cement ratio is 0.54; the concrete density is 2380 kg / m³; the initial setting time is 6 hours, the final setting time is 9 hours, there is no strength after 12 hours, the compressive strength after 28 days is 29.4 MPa, and the raw material cost per m³ of concrete is 275.0 yuan.

[0036] To fully demonstrate the superior performance of the tunnel invert and the early-strength aggregate polymer concrete filling for the invert of the present invention, and to facilitate performance comparison, the concrete formulation parameters of the above embodiments are preferably summarized in this embodiment: Table 1 is a comparison table of parameter information for the early-strength aggregate polymer concrete formulas used in the tunnel invert and invert filling for Examples 1-6.

[0037] Regarding the effectiveness verification data: Table 2 is a summary table of the performance tests of the tunnel invert and the early-strength aggregate polymer concrete filling for Examples 1-6.

[0038] Table 3 is a summary table of parameter information and performance test information for the comparative examples.

[0039] The above embodiments describe only the basic principles, main features and / or advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and the description of the invention content in the specification are only the principles or specific cases of the present invention. Without departing from the essence of the innovative idea of ​​the present invention, there are various changes and improvements to the innovative solution of the present invention, and all such changes and improvements fall within the scope of protection claimed by the present invention.

Claims

1. A tunnel invert arch and the early-strength aggregate-polymer concrete for filling the invert arch, characterized in that, The raw materials include the following volume fractions: 58-60 parts of aggregate and 40-42 parts of early-strength grout; In the aforementioned early-strength aggregate polymer concrete, the strength grade of the tunnel invert arch portion shall not be lower than C25, and the strength grade of the tunnel invert arch filling portion shall not be lower than C15. The preparation method of the early-strength grout-aggregate polymer concrete is as follows: the early-strength grout is injected into the pre-stacked aggregate to wrap the aggregate and fill the voids in the aggregate, and then cured to form the concrete. The aggregate includes coarse aggregates of three particle sizes: 4.75–9.5 mm, 9.5–20 mm, and 16–31.5 mm; the ratio of the parent rock compressive strength of the coarse aggregate to the design compressive strength of the concrete is not less than 1.

5. The 12h, 28d, and 60d compressive strength of the early-strength grouting material shall not be lower than the 12h, 28d, and 60d design compressive strength of the corresponding early-strength grout-aggregate polymer concrete. The early-strength slurry per cubic meter comprises the following raw materials: Sulfoaluminate cement 500-600kg, Class F II fly ash 400-500kg, industrial sand 600-800kg, water 400-450kg, water-reducing agent 10.8-19.8kg, retarder 0.18-0.66kg; The total binder of the early-strength grouting material includes sulfoaluminate cement and Class F II fly ash, and the mass of the total binder is 900-1100 kg / m³. The water-cement ratio of the early-strength grout is 0.36-0.5; The industrial sand has a particle size of 0.075-2.36 mm, a fineness modulus of no more than 1.8, a porosity of 20-30%, a water absorption rate of 0.8-5.0%, and a silica content of 30-45%.

2. The tunnel invert and the early-strength aggregate polymer concrete filling the invert as described in claim 1, characterized in that, The water-reducing agent is a comb-shaped polycarboxylate-based water-reducing agent, the water reduction rate of the water-reducing agent is not less than 25%, and the dosage of the water-reducing agent accounts for 1.2~1.8% of the total adhesive material content.

3. The tunnel invert and the early-strength aggregate polymer concrete filling the invert as described in claim 1, characterized in that, The retarder includes a sugar retarder and a hydroxycarboxylic acid retarder, with a mass ratio of 1:1.5-2.

5. The amount of the retarder is 0.2-0.6‰ of the total amount of the adhesive material.

4. The tunnel invert and the early-strength aggregate polymeric concrete filling the invert according to any one of claims 1-3, characterized in that, The working performance of the early-strength grout is as follows: the initial flow cone time is not greater than 18s, and the 2h flow cone time is not greater than 35s; the initial truncated cone flowability is not less than 400mm, and the 2h truncated cone flowability is not less than 350mm.

5. The tunnel invert and the early-strength aggregate polymeric concrete filling the invert according to any one of claims 1-3, characterized in that, The 28-day shrinkage and expansion rate of the early-strength grouting material satisfies the formula: (δ △ +δ v )+δ c ≤r; where r is the design value of the 28-day shrinkage and expansion rate of the tunnel invert or the early-strength aggregate polymer concrete filling the invert; δ △ δ is the design value for the expansion rate of the early-strength grout; v δ represents the design value for shrinkage constraint of coarse aggregate on early-strength grout; c This is the design value for the shrinkage rate of early-strength grouting material.

6. A construction method for the tunnel invert and the early-strength aggregate polymer concrete filling the invert as described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Tie the reinforcing steel bars of the tunnel invert layer and construct the overall formwork for the tunnel invert layer; Step 2: Fill the openings in the tunnel invert arch formwork with the first aggregate, which is filled by free stacking. Step 3: After the first aggregate is filled, pour early-strength grout into the first aggregate through the opening in the template; Step 4: After the early-strength grouting material for the tunnel invert layer is poured, immediately cover it with a thick plastic film for moisture retention and curing; after the strength is not less than 75% of the design strength, remove the formwork, cover it with a thick plastic film for continued moisture retention and curing, until the next construction process is carried out. Step 5: Erect the formwork for the tunnel invert arch filling layer; Step 6: Fill the tunnel invert arch filling layer template with the second aggregate. The second aggregate is filled by free stacking. Step 7: After the second aggregate is filled, pour early-strength grout into the second aggregate; Step 8: After the early-strength grouting material for the tunnel invert arch filling layer is poured, immediately cover the top surface with a thick plastic film for moisture retention and curing; after the strength reaches the design requirements, remove the formwork and cover with a thick plastic film to continue moisture retention and curing for at least 3 days.

7. The construction method according to claim 6, characterized in that, In step 2, the first aggregate in the tunnel invert layer has a particle size of 9.5-20mm coarse aggregate; in step 6, the second aggregate in the tunnel invert filling layer is 4.75-9.5:9.5-20:16-31.5mm coarse aggregate, forming a gradation of 1:5:4, or 1:6:3, or 1:3:

6.

8. The construction method according to claim 6, characterized in that, In steps 3 and 7, the early-strength grout is injected either by direct pouring or by filling from the bottom up using a conduit.

9. The construction method according to claim 6, characterized in that, In steps 4 and 8, within 5 minutes after the early-strength grout is injected, cover it with a 0.08-0.15mm thick plastic film.

10. The construction method according to claim 6, characterized in that, If the flowability of the early-strength grout is less than 350mm, pouring should be stopped immediately. During construction, the longitudinal length of the pouring section should be controlled according to the duration of performance maintenance to avoid loss of performance and resulting in incomplete filling.

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