Slurry bone polymeric concrete for tunnel secondary lining and construction method

Abstract

The invention provides slurry bone polymeric concrete for a tunnel secondary lining and a construction method, and relates to the technical field of tunnel concrete materials and construction methods. In the slurry bone polymer concrete, the aggregate is formed by one or two ranges of coarse aggregates and is compactly piled and filled, the proportion of the formed skeleton is larger, a stronger inhibition effect on the hardening shrinkage of the slurry can be achieved, and the shrinkage rate is remarkably reduced while the structural strength is guaranteed; industrial sand with spherical appearance, activity and water storage and maintenance functions is screened as fine aggregate to be used for slurry, the fluidity, the strength and the shrinkage resistance are improved, a trace amount of nano silicon dioxide is further doped, the fluidity is not affected, and the compression resistance, the breaking strength and the anti-permeability performance can be synergistically improved; in addition, the aggregate is piled up in advance, then the slurry is injected to fill and wrap the aggregate, the energy consumption of traditional concrete aggregate reciprocating transportation and whole raw material stirring can be reduced, and the pouring method of the tunnel secondary lining is simple in process, high in efficiency, low in cost, little in pollution and good in forming quality.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials and construction methods, in particular to the technical field of concrete materials and construction methods for tunnels, and specifically to a mortar-bone polymer concrete for tunnel secondary lining and a construction method. Background Art

[0002] With the rapid development of my country's infrastructure construction, the number of tunnel projects continues to increase. As an important component of tunnels, the quality of tunnel secondary lining concrete structures is directly related to the safety and durability of tunnels. However, existing tunnel secondary lining concrete materials and construction methods have some urgent problems that need to be solved.

[0003] Existing tunnel secondary lining concrete materials are primarily formulated using Portland cement, fly ash, coarse and fine aggregates, water reducers, and water, which are mixed together. While these existing concrete materials can meet the construction requirements of tunnel secondary lining structures to a certain extent, they still have shortcomings in controlling shrinkage. During the hardening process, concrete experiences significant shrinkage due to shrinkage caused by cement hydration, drying shrinkage due to water evaporation, and shrinkage due to temperature fluctuations. High shrinkage can cause cracks in the concrete structure, impacting its mechanical and waterproof properties. Therefore, existing tunnel secondary lining concrete materials typically require the addition of large amounts of admixtures (such as high-efficiency water-reducing and anti-shrinkage agents and expansion agents) to improve their performance. However, these admixtures are limited in effectiveness and are expensive, increasing the overall cost of concrete. In addition, the existing tunnel secondary lining construction methods mostly use traditional concrete mixing and pouring methods, which involve the mining and crushing of coarse aggregate and then transporting it to the mixing plant. All raw materials are mixed as a whole using high-power equipment and then transported to the site for pouring. There is energy consumption in the reciprocating transportation of coarse aggregate, construction investment in the high-power mixing plant, and energy consumption in the mixing of the mixing plant. Not only is the energy consumption high and the carbon emissions large, but it also generates noise and dust pollution. Furthermore, the integrally mixed concrete has the risk of segregation between the coarse aggregate and the cementitious material during the pouring process. The height of the concrete entering the mold and the height difference of the concrete pouring on both sides must be strictly controlled. It must be vibrated while pouring. The construction process is complex, there are many supporting personnel, many control links, and it is difficult to manage, which is prone to quality defects.

[0004] Therefore, developing a new type of tunnel secondary lining concrete material and its pouring method is of great significance for improving the quality of tunnel secondary lining structure, reducing construction costs and improving construction efficiency. Summary of the Invention

[0005] The purpose of the present invention is to overcome the technical defects of existing concrete materials used for tunnel secondary lining, such as large shrinkage, low construction efficiency, high cost and large carbon emissions, and propose a mortar-bone polymer concrete for tunnel secondary lining and a casting method for tunnel secondary lining.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides a mortar-bone polymer concrete for tunnel secondary lining, comprising the following raw materials in parts by weight: 58-60 parts of aggregate, 40-42 parts of mortar; The aggregate comprises coarse aggregates in two particle size ranges: 9.5-20 mm and 16-31.5 mm; one or two of the coarse aggregates in the two particle size ranges are mixed in a certain proportion to form the aggregate; the ratio of the parent rock compressive strength of the coarse aggregate to the design compressive strength of the tunnel secondary lining is not less than 1.5; The slurry is a high-flow grouting material containing fine aggregate, and each cubic meter of the high-flow grouting material includes the following raw materials by weight: 500-600 kg of cement, 300-400 kg of fly ash, 800-1000 kg of industrial sand, 350-400 kg of water, 6.4-15 kg of water reducer, and 0.8-2 kg of nano-silicon dioxide; The total adhesive material of the high-fluidity grouting material is 800-1000kg, and the water-binder ratio is 0.35-0.5; The industrial sand has a particle size of 0.075-2.36 mm, a fineness modulus of no more than 2.0, a porosity of 20-40%, a water absorption rate of 0.8-5%, a silica content of 35-50%, and an activity index of no less than 65% after 28 days of testing after grinding; The mortar-bone aggregate concrete is formed in the following manner: the aggregate and the mortar are prepared separately, and during construction, the coarse aggregate is first piled up and then the mortar is poured to fill the gaps in the coarse aggregate and solidify to form the mortar-bone aggregate concrete.

[0007] The present invention provides a grout-bone aggregate concrete for tunnel secondary lining, which is composed of aggregate and high-flow grouting material (hereinafter referred to as "grout"). The aggregate formed by compacting a single or two ranges of coarse aggregate accounts for more than 58%. Compared with conventional concrete with an aggregate content of no more than 50%, the skeleton in the grout-bone aggregate concrete can exert a stronger inhibitory effect on the hardening shrinkage of the grout, not only significantly reducing the material shrinkage rate, but the hard aggregate also provides the concrete with sufficient strength and elastic modulus. By screening industrial sand with spherical shape, activity and water storage and curing functions as fine aggregate, it is added to cementitious materials to form a slurry. By adjusting the consistency of the cementitious material, the industrial sand is evenly suspended in the slurry to avoid segregation. At the same time, the spherical shape of the industrial sand provides a ball effect for the slurry, which makes it have higher fluidity, which are important indicators for the slurry to fully fill the aggregate voids. By controlling the particle size, fineness modulus and silica content, the proportion of reactive fine aggregate in the industrial sand is increased. At the same time, the smaller the particle size of the industrial sand, the larger the specific surface area, the stronger the adsorption capacity, the more complete the contact with cement and other cementitious materials, the more intense the chemical reaction caused, and the further promoted the reaction with cement hydrated calcium hydroxide to form calcium silicate gel, thereby enhancing the strength and durability of the slurry. There are irregular holes on the surface of the industrial sand particles, which have water storage function, providing internal curing moisture for the later hardening of the slurry and playing an anti-shrinkage role. Furthermore, adding a small amount of nano-silica into the slurry fills the pores between the aggregate and the slurry, reduces the porosity of the interface transition zone, optimizes the performance of the interface transition zone, and makes the structure denser. It not only does not affect the fluidity, but also synergistically improves the compressive strength, flexural strength and anti-permeability properties.

[0008] Among them, the cement is preferably ordinary Portland cement 42.5.

[0009] Among them, preferably, among the aggregates, one can be selected from two coarse aggregates with different particle size ranges, or they can be mixed in a mass ratio of 0.33-3:1; that is, the weight mixing ratio of coarse aggregate with a particle size range of 9.5-20 mm and coarse aggregate with a particle size range of 16-31.5 mm is 0.33-3:1.

[0010] The optimal aggregate mass ratio condition results in a higher aggregate skeleton bulk density, a lower bulk porosity, less slurry, a stronger skeleton constraint, and a smaller shrinkage rate of the slurry-bone aggregate concrete, making it more suitable for tunnel secondary lining structures.

[0011] Among them, the industrial sand refers to the waste material left over from mining or industrial processing. After processing and screening, it can be used to prepare high-fluidity grouting materials, which has the advantages of low cost and wide source.

[0012] Among them, preferably, the fly ash is secondary fly ash; the preferred fly ash can better improve the durability and crack resistance of concrete.

[0013] Among them, preferably, the particle size of the nano-silica is 50-200 nm; the larger the particle size, the less conducive it is to filling the pores, and the smaller the particle size, the worse the dispersibility.

[0014] Among them, preferably, the water reduction rate of the water reducer is not less than 25%; more preferably, the water reducer is a polycarboxylic acid water reducer with a comb-like structure; such as polyester polycarboxylic acid water reducer and polyether polycarboxylic acid water reducer.

[0015] Preferably, the high-fluidity grouting material further comprises 0.08-0.3 kg of retarder per cubic meter. The addition of retarder can prolong the setting time of concrete, reduce the hydration heat release rate, and improve the working performance of the slurry.

[0016] More preferably, the retarder is a sugar retarder, such as glucose, fructose, sucrose, starch, and cellulose.

[0017] Among them, preferably, each cubic meter of the high-fluidity grouting material also includes 0.08-0.25 kg of defoaming agent; the addition of the defoaming agent can reduce bubbles in the gelling grouting material, reduce the number of pores on the surface of the mortar-bone polymer concrete after curing, and improve the strength of the concrete.

[0018] More preferably, the defoaming agent is a polyether defoaming agent, such as glycerol polyether defoaming agent (GP defoaming agent), glycerol polyoxypropylene oxyethylene ether defoaming agent (GPE defoaming agent), silicone modified polyether defoaming agent (GPES defoaming agent), polypropylene glycol defoaming agent (PPG type defoaming agent), ethylene oxide-propylene oxide block copolymer defoaming agent (EO / PO copolymer defoaming agent).

[0019] Preferably, each cubic meter of the slurry further includes 0.5-0.9 kg of organic short fiber material; by adding organic short fiber material, the toughness and crack resistance of the concrete can be increased, which is beneficial to improving the mechanical properties of the concrete.

[0020] Preferably, the organic short fiber material has a diameter of 20-25 μm, a length of 3-6 mm, and a tensile strength of not less than 350 MPa; the preferred fiber material of the present invention has better dispersibility and better effect on improving the mechanical properties of mortar-bone polymer concrete.

[0021] Preferably, the organic short fiber material is polypropylene fiber.

[0022] Among them, the industrial sand in the high-fluidity grouting material of the present invention has a spherical shape and a ball-rolling effect compared to ordinary sand due to the grinding effect on the industrial production line, but has a larger particle size than silica fume, microbeads, etc., so the water requirement is smaller; at the same time, the high-fluidity grouting material is not mixed with the aggregate, which avoids the water being carried away by the aggregate, greatly improving the fluidity of the slurry.

[0023] Preferably, the initial flow cone time of the high-fluidity grouting material is not greater than 18s, and the 3h flow cone time is not greater than 35s; the initial truncated cone fluidity is not less than 360mm, and the 3h truncated cone fluidity is not less than 320mm; under a pressure of 0.36MPa, the water seepage rate is not greater than 1%.

[0024] Preferably, the 28d shrinkage and expansion ratio of the high-fluidity grouting material satisfies the formula: δ △ +(δ v +δ c )≤r; where r is the design value of the shrinkage and expansion rate of the tunnel secondary lining over 28 days; δ △ is the design value of the expansion rate of high-flow grouting material; δ v is the design value of aggregate shrinkage; δ c It is the design value of shrinkage of high-flow grouting material.

[0025] Among them, preferably, the mortar-bone aggregate concrete is prepared by filling the pores of the accumulated aggregate with a high-fluidity grouting material and then solidifying it, that is, first filling the aggregate in the formwork and then solidifying it by pouring the high-fluidity grouting material; the preferred preparation method can avoid the costs of stone transportation, mixing energy consumption, etc., and can significantly reduce the cost of concrete.

[0026] Furthermore, in order to achieve the above-mentioned object of the invention, the present invention provides a construction method of the mortar aggregate concrete for the secondary lining of the tunnel according to the above-mentioned method, which specifically comprises the following steps: Step 1: Assemble the integral formwork of the tunnel secondary lining, and preset grouting holes at the bottom of the arch foot on both sides of the tunnel secondary lining formwork, and preset exhaust holes at the top of the formwork; the longitudinal spacing of the grouting holes is 3-6m, and the longitudinal spacing of the exhaust holes is 0.5-1m; Step 2: Filling the secondary tunnel lining template with aggregate to form a skeleton; the aggregate is densely packed by its own weight; Step 3: After the aggregate filling is completed, the grouting holes and 3-5 adjacent vent holes on the same section are opened, and the remaining grouting holes and vent holes are kept closed, and high-fluidity grouting material is poured through the preset grouting holes; Step 4: Pressure-inject high-fluidity grouting material from bottom to top, with the maximum pump pressure not exceeding 2 MPa, until uniform slurry continuously overflows from the exhaust hole, and the injection is completed; Step 5: After the high-fluidity grouting material is poured, the grouting holes and the vent holes are sealed; Step 6: Repeat steps 2 to 5 until the grouting of the mortar-bone aggregate concrete along the entire length of the tunnel is completed. Step 7: After the strength of the tunnel secondary lining mortar-bone polymer concrete meets the requirements, the formwork is removed. After the formwork is removed, the mortar-bone polymer concrete is subjected to moisturizing maintenance to obtain the tunnel secondary lining mortar-bone polymer concrete structure.

[0027] The present invention provides a method for pouring concrete for a tunnel secondary lining, which forms a tunnel secondary lining mortar-bone aggregate concrete by pre-stacked aggregates and then injecting slurry to fill and wrap the aggregates. Aggregates are sourced and used locally, which can reduce the energy consumption of traditional concrete aggregate transportation. The slurry can be mixed using a mobile slurry making machine of ordinary power, and can be produced and used nearby, saving the investment cost of large, fixed mixing stations and reducing the energy consumption of mixing all raw materials as a whole. It also avoids the risk of initial setting of the prepared slurry during long-distance transportation. The pouring method for the tunnel secondary lining of the present invention has the advantages of fast slurry flow, no need for vibration, and the ability to complete full-section construction at one time. It has the advantages of simple process, high efficiency, low cost, and low pollution. In addition, the slurry can penetrate all pores, fully filling the gap between the aggregate and the formwork to form a dense and smooth surface, and the apparent molding quality of the tunnel secondary lining is better. This invention not only provides a concrete material that meets the requirements, changes the existing concrete production model, reduces carbon emissions, improves molding quality, and saves costs, but also further consumes solid waste materials such as industrial sand, turning waste into treasure, making a huge contribution to environmental protection, and can be used on a large scale in tunnel secondary lining structures.

[0028] Further preferably, in step 1, the diameter of the grouting hole is 2-5 cm; the preferred grouting hole diameter is conducive to the rapid injection of high-fluidity grouting material.

[0029] Preferably, the diameter of the vent hole is 5-10 mm. The preferred vent hole diameter is conducive to the discharge of gas inside the template during the pouring of high-fluidity grouting material, while ensuring that the top of the tunnel secondary lining is fully poured.

[0030] Further preferably, in step 2, preferably, after the aggregate is piled up, the porosity is about 40-45%.

[0031] Among them, in step 3, preferably, the perfusion pressure is not greater than 2 MPa; the requirements for the perfusion equipment are smaller, which is conducive to reducing equipment costs.

[0032] Further preferably, in step 4, when grouting material overflows from the exhaust hole, it indicates that the grouting is completed.

[0033] In step 7, the curing method includes: controlling the humidity of the concrete surface to above 90%; ensuring that the temperature difference between the concrete interior and surface does not exceed 20°C, and that the temperature difference between the concrete surface and the surrounding environment does not exceed 20°C; and curing for at least 14 days. This facilitates the hydration of the mortar-bone aggregate concrete, ensuring both internal and surface hydration of the concrete, thereby reducing concrete shrinkage and ensuring surface quality.

[0034] Compared with the prior art, the present invention has the following beneficial effects: 1. The mortar-bone aggregate concrete of the present invention uses a single or two ranges of coarse aggregates for dense filling, forming a larger proportion of the skeleton, which can exert a stronger inhibitory effect on the hardening shrinkage of the mortar, ensuring structural strength while significantly reducing the shrinkage rate and reducing the risk of shrinkage cracking of the tunnel secondary lining.

[0035] 2. The mortar-bone aggregate concrete used for the secondary lining of tunnels of the present invention selects spherical industrial sand with activity and water storage and maintenance functions as fine aggregate for the preparation of the slurry, thereby improving fluidity, strength and shrinkage resistance. It further incorporates a trace amount of nano-silicon dioxide to synergistically improve the compressive strength, flexural strength and anti-seepage properties. This not only disposes of industrial solid waste materials, but also turns waste into treasure, making a great contribution to environmental protection.

[0036] 3. The present invention's secondary tunnel lining pouring method utilizes a construction method that first fills the secondary tunnel lining formwork with aggregate and then pours a high-fluidity grout. This reduces the energy consumption associated with conventional concrete aggregate transportation and overall mixing of all raw materials, significantly lowering construction costs. This pouring method also eliminates the need for vibration, saving steps and labor, and improving pouring efficiency.

[0037] 4. The pouring method of the tunnel secondary lining of the present invention utilizes the excellent fluidity of the high-fluidity grouting material to fully fill the gap between the aggregate and the formwork, so that the surface of the tunnel secondary lining formed is dense and smooth, and the apparent molding quality is better.

[0038] 5. The method for pouring the tunnel secondary lining of the present invention reduces carbon emissions, improves molding quality, and saves costs, and is suitable for large-scale pouring construction of tunnel secondary lining mortar-bone polymer concrete structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the initial grouting after the secondary lining of the tunnel is filled with aggregate in the technical solution of the present invention.

[0040] Figure 2 This is a schematic diagram of the completion of the secondary lining grouting of the tunnel in the technical solution of the present invention.

[0041] Figure 3 This is a schematic diagram of the tunnel secondary lining reaching the designed strength and undergoing the curing stage in the technical solution of the present invention.

[0042] Figure 4 This is a schematic diagram of a simulation test in which aggregate and slurry are filled separately in the technical solution of the present invention.

[0043] Figure 5 This is a schematic diagram of an experiment of filling slurry in aggregate in the technical solution of the present invention.

[0044] Figure numerals: 1-aggregate; 2-slurry; 3-grouting hole; 4-vent hole; 5-surrounding rock; 6-tunnel secondary lining. DETAILED DESCRIPTION

[0045] In order to more clearly describe the purposes, technical solutions and technical effect advantages of the specific embodiments of the present application, the following will make a detailed description of the solutions in the specific embodiments in conjunction with the drawings of the present application.

[0046] The specific technical solutions involved in the following specific embodiments are only for clearly and completely describing the innovative technical solutions of the present application, and only a part of the specific embodiments of the present application can be adopted, not all the embodiments, and should not be understood as a limitation of the innovative solutions of the present application. Any solutions adopting the same inventive concept of the present application should be included in the protection scope of the present application.

[0047] In the specific embodiments of the present application, the designed compressive strength of the tunnel secondary lining is 30 MPa.

[0048] The present embodiment discloses a construction method of slurry-bone polymerized concrete for tunnel secondary lining, as shown in Figure 1-Figure 3 The present embodiment discloses a construction method of slurry-bone polymerized concrete for tunnel secondary lining, as shown in Specifically includes the following steps: Step 1, assemble the tunnel secondary lining 6 overall formwork, and preset the grouting hole 3 at the bottom position of the arch foot on both sides of the tunnel secondary lining 6 formwork, and preset the exhaust hole 4 at the arch top position; the longitudinal setting interval of the grouting hole 3 is 3-6 m, and the longitudinal setting interval of the exhaust hole 4 is 0.5-1 m; wherein the diameter of the grouting hole 3 is preferably 2-5 cm; in the present embodiment, the diameter of the grouting hole 3 is set to 5 cm; the diameter of the exhaust hole 4 is preferably 5-10 mm; in the present embodiment, the diameter of the exhaust hole 4 is set to 10 mm; Step 2, fill the aggregate in the tunnel secondary lining 6 formwork to form a framework; the filling of the aggregate relies on the self-weight tight stacking; after the aggregate filling is completed, the porosity is about 40-45%.

[0049] Step 3, after the aggregate filling is completed, open the grouting hole 3 and the adjacent 3-5 exhaust holes 4 on the same section, and maintain the rest in a closed state, and pour high-flow grouting material through the preset grouting hole 3; preferably, the pouring pressure is not greater than 2 MPa; in the present embodiment, it is set to 2 MPa.

[0050] Step 4, pour high-flow grouting material from bottom to top, the maximum pump pressure is not more than 2 MPa, until uniform slurry 2 continuously overflows from the exhaust hole 4, and the pouring is completed; Step 5, after the high-flow grouting material pouring is completed, seal the grouting hole 3 and the exhaust hole 4; Step 6, repeat steps 2-5 until the slurry-bone polymerized concrete filling pouring of all tunnel design lengths is completed; Step 7, after the strength of the tunnel secondary lining slurry-bone polymerized concrete meets the requirements, the formwork is removed, and the slurry-bone polymerized concrete is maintained after the formwork is removed, to obtain the tunnel secondary lining 6 slurry-bone polymerized concrete structure.

[0051] As shown in Figure 4-Figure 5 Fig. 1 is a schematic view of a simulation test of a slurry-bone polymerized concrete pouring method, the upper drawing is a state of only filling the aggregate, and the lower drawing is a schematic view of the slurry filling into the gap of the aggregate.

[0052] According to the specific embodiment, the concrete formula is adjusted and set as follows in the embodiment to investigate the excellent technical effects possessed by the method.

[0053] Embodiment 1 A slurry-bone polymerized concrete for a tunnel secondary lining, which is solidified by the following weight parts of raw materials: 59 parts of aggregate 1 and 41 parts of slurry; In the aggregate, the mass ratio of coarse aggregate with a particle size of 9.5-20 mm to coarse aggregate with a particle size of 16-31.5 mm is 1:1; the compressive strength of the coarse aggregate is greater than 45 MPa; The following weights of raw materials are mixed per cubic meter of the slurry to form the slurry: 550 kg of cement (P·O42.5), 350 kg of fly ash (second-grade fly ash), 900 kg of industrial sand (particle size of 0.075-2.36 mm, fineness modulus of 1.8, porosity of 28%, water absorption rate of 2.8%, and silicon dioxide content of 43%), 360 kg of water, 10 kg of water reducing agent (polyester type polycarboxylic acid water reducing agent), and 1.5 kg of nano silicon dioxide (particle size of 100 nm); the water-binder ratio of the slurry is 0.40.

[0054] The slurry-bone polymerized concrete is formed according to the following manner: the aggregate and the slurry are respectively prepared, and in construction, the aggregate is first stacked, and then the slurry is poured to fill the slurry into the gap of the aggregate to solidify the slurry-bone polymerized concrete.

[0055] The performance test results of the tunnel secondary lining slurry-bone polymerized concrete are summarized in Table 2.

[0056] Embodiment 2 A slurry-bone polymerized concrete for a tunnel secondary lining, which is solidified by the following weight parts of raw materials: 60 parts of aggregate and 40 parts of slurry; In the aggregate, the mass ratio of coarse aggregate with a particle size of 9.5-20 mm to coarse aggregate with a particle size of 16-31.5 mm is 3:1; the compressive strength of the coarse aggregate is greater than 45 MPa; The following weights of raw materials are mixed per cubic meter of the slurry to form the slurry: 500kg of cement (P∙O42.5), 300kg of fly ash (secondary fly ash), 1000kg of industrial sand (particle size 0.075-2.36mm, fineness modulus 2.0, porosity 20%, water absorption 2%, silica content 50%), 400kg of water, 6.4kg of water reducer (polyester polycarboxylate water reducer), 0.8kg of nano-silica (particle size 50nm); the water-cement ratio of the slurry is 0.5.

[0057] The performance test results of the tunnel secondary lining mortar aggregate concrete are summarized in Table 2.

[0058] Example 3 A mortar aggregate concrete for tunnel secondary lining, comprising the following raw materials in parts by weight and solidified: 58 parts aggregate, 42 parts paste; Among the aggregates, the mass ratio of coarse aggregate with a particle size of 9.5-20 mm to coarse aggregate with a particle size of 16-31.5 mm is 0.33:1; the compressive strength of the coarse aggregate is greater than 45 MPa; Each cubic meter of the slurry comprises a mixture of the following raw materials by weight: 600kg of cement (P∙O42.5), 400kg of fly ash (secondary fly ash), 800kg of industrial sand (particle size 0.075-2.36mm, fineness modulus 1.8, porosity 26%, water absorption 2.5%, silica content 48%), 350kg of water, 15kg of water reducer (polyester polycarboxylate water reducer), 2kg of nano-silica (particle size 200nm); the water-cement ratio of the slurry is 0.35.

[0059] The performance test results of the tunnel secondary lining mortar aggregate concrete are summarized in Table 2.

[0060] Example 4 A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: Among the aggregates, the mass ratio of coarse aggregate with a particle size of 9.5-20 mm to coarse aggregate with a particle size of 16-31.5 mm is 3:1.

[0061] Example 5 A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: Among the aggregates, the mass ratio of coarse aggregate with a particle size of 9.5-20 mm to coarse aggregate with a particle size of 16-31.5 mm is 0.33:1.

[0062] Example 6 A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: The particle size of industrial sand is 0.075-2.36mm, the fineness modulus is 1.6, the porosity is 20%, the water absorption rate is 2%, and the silica content is 50%.

[0063] Comparative Example 1 A mortar aggregate concrete for tunnel secondary lining, the composition of which is exactly the same as that of Example 1, with the only difference being: After the aggregate and slurry are pre-mixed evenly, they are poured into the formwork as a whole to solidify and form the structure. Comparative Example 1 adopts the traditional construction process of first mixing the whole and then pouring.

[0064] Comparative Example 2 A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: Natural river sand was used to replace industrial sand. The river sand had a particle size of 0.5-4.75 mm, a fineness modulus of 3, a porosity of 40%, a water absorption rate of 0.9%, and a silica content of 90%. Comparative Example 2 used natural river sand.

[0065] Comparative Example 3 A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: The industrial sand has a particle size of 0.075-2.36 mm, a fineness modulus of 2.2, a porosity of 28%, a water absorption rate of 2.8%, and a silica content of 43%. The fineness modulus of the industrial sand in Comparative Example 3 exceeds the preferred range.

[0066] A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: The industrial sand has a particle size of 0.075-2.36 mm, a fineness modulus of 1.8, a porosity of 8%, a water absorption of 0.5%, and a silica content of 43%. In Comparative Example 4, the porosity and water absorption of the industrial sand exceeded the preferred range.

[0067] Comparative Example 5 A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: The particle size of the coarse aggregate is 16-31.5 mm. The particle size range of the coarse aggregate is narrower than that of Example 1.

[0068] Comparative Example 6 A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: The particle size of the coarse aggregate is 4.75-9.5 mm. The particle size range of the coarse aggregate is narrower than that of Example 1, and the particle size is relatively small.

[0069] Comparative Example 7 A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: No nano-silicon dioxide is added into each cubic meter of the slurry.

[0070] Comparative Example 8 A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: The amount of cement (P∙O 42.5) used in each cubic meter of the slurry was 450 kg, which was lower than the preferred range.

[0071] Comparative Example 9 A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: The amount of cement (P∙O42.5) used in each cubic meter of the slurry was 650 kg, which exceeded the preferred range.

[0072] Comparative Example 10 A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: The amount of fly ash (secondary fly ash) used in each cubic meter of the slurry is 250 kg, which is lower than the preferred range.

[0073] Comparative Example 11 A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: The amount of fly ash (secondary fly ash) in each cubic meter of the slurry is 450 kg, which is higher than the preferred range.

[0074] Comparative Example 12 A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: The amount of industrial sand used in each cubic meter of the slurry is 750 kg, which is lower than the preferred range.

[0075] Comparative Example 13 A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: The amount of industrial sand in each cubic meter of the slurry is 1050 kg, which is higher than the preferred range.

[0076] Comparative Example 14 A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: The amount of water used in each cubic meter of the slurry was 270 kg, and the water-binder ratio was 0.30, which is lower than the preferred range.

[0077] Comparative Example 15 A mortar aggregate concrete for tunnel secondary lining, the composition of which is substantially the same as that of Example 1, with the only difference being: The amount of water used in each cubic meter of the slurry was 495 kg, and the water-binder ratio was 0.55, which is higher than the preferred range.

[0078] The mix ratios of the tunnel secondary lining mortar-bone polymer concrete of Examples 1 to 6 and Comparative Examples 1 to 15 are summarized in Table 1. Examples 1 to 6 are referred to as Examples 1 to 6, and Comparative Examples 1 to 15 are referred to as Comparative Examples 1 to 15.

[0079] Table 1 Summary of parameter data of tunnel secondary lining mortar-bone polymer concrete of Examples 1 to 6 and Comparative Examples 1 to 15

[0080] The performance of the tunnel secondary lining mortar-bone polymer concrete in Examples 1 to 6 and Comparative Examples 1 to 15 was tested, and the raw material costs were statistically analyzed. The results are summarized in Table 2. Among them, Examples 1 to 6 are referred to as Examples 1 to 6, and Comparative Examples 1 to 15 are referred to as Comparative Examples 1 to 15. The 28d compressive strength of ordinary C30 concrete is ≥30MPa, and the shrinkage rate is about 250×10 -6 , the material cost is about 365 yuan / m³.

[0081] Table 2 Experimental data of tunnel secondary lining mortar-bone polymer concrete in Example 1-Example 6 and Comparative Example 1-Comparative Example 15

[0082] Analysis of the data in Table 2 shows that tunnel secondary lining mortar-bone aggregate concrete has certain performance and cost advantages. In the embodiments of the present invention, the aggregate is densely packed with a single or two ranges of coarse aggregate, forming a larger proportion of the skeleton, which can exert a stronger inhibitory effect on the hardening shrinkage of the slurry, ensuring structural strength while significantly reducing the shrinkage rate. By screening spherical industrial sand with active and water-storage curing functions as fine aggregate for the slurry, the fluidity, strength, and shrinkage resistance are improved. Further incorporation of trace amounts of nano-silica does not affect fluidity and can synergistically improve compressive and flexural strength and impermeability. Moreover, pre-stacked aggregates and then injected with slurry to fill and encapsulate the aggregates can reduce the energy consumption of traditional concrete aggregate transportation and overall mixing of all raw materials.

[0083] 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 above embodiments and the invention content of the specification only describe the principles or specific cases of the present invention. Without departing from the essence of the innovative ideas of the present invention, the innovative solutions of the present invention may be subject to various changes and improvements, and these changes and improvements all fall within the scope of protection claimed by the present invention.

Claims

1. A mortar aggregate concrete for tunnel secondary lining, characterized in that: The raw materials include the following parts by weight: 58-60 parts of aggregate, 40-42 parts of slurry; The aggregate comprises coarse aggregates in two particle size ranges: 9.5-20 mm and 16-31.5 mm; one or two of the coarse aggregates in the two particle size ranges are mixed in a certain proportion to form the aggregate; the ratio of the parent rock compressive strength of the coarse aggregate to the design compressive strength of the tunnel secondary lining is not less than 1.5; The slurry is a high-flow grouting material containing fine aggregate, and each cubic meter of the high-flow grouting material includes the following raw materials by weight: 500-600 kg of cement, 300-400 kg of fly ash, 800-1000 kg of industrial sand, 350-400 kg of water, 6.4-15 kg of water reducer, and 0.8-2 kg of nano-silicon dioxide; The total adhesive material of the high-fluidity grouting material is 800-1000kg, and the water-binder ratio is 0.35-0.5; The industrial sand has a particle size of 0.075-2.36 mm, a fineness modulus of no more than 2.0, a porosity of 20-40%, a water absorption rate of 0.8-5%, a silica content of 35-50%, and an activity index of no less than 65% after 28 days of testing after grinding; The mortar-bone aggregate concrete is formed in the following manner: the aggregate and the mortar are prepared separately, and during construction, the coarse aggregate is first piled up and then the mortar is poured to fill the gaps in the coarse aggregate and solidify to form the mortar-bone aggregate concrete.

2. The mortar aggregate concrete for tunnel secondary lining according to claim 1, characterized in that: In the aggregate, the weight mixing ratio of coarse aggregate with a particle size range of 9.5-20 mm and coarse aggregate with a particle size range of 16-31.5 mm is 0.33-3:

1.

3. The mortar aggregate concrete for tunnel secondary lining according to claim 1, characterized in that: Each cubic meter of the high-fluidity grouting material also includes 0.08-0.3 kg of retarder.

4. The mortar aggregate concrete for tunnel secondary lining according to claim 3, characterized in that: Each cubic meter of the high-fluidity grouting material also includes 0.08-0.25 kg of defoaming agent.

5. The mortar aggregate concrete for tunnel secondary lining according to claim 4, characterized in that: Each cubic meter of the high-fluidity grouting material also includes 0.5-0.9 kg of organic short fiber material.

6. The mortar aggregate concrete for tunnel secondary lining according to any one of claims 1 to 5, characterized in that: The high-fluidity grouting material has an initial flow cone time of no more than 18 seconds and a 3-hour flow cone time of no more than 35 seconds; an initial truncated cone fluidity of no less than 360 mm and a 3-hour truncated cone fluidity of no less than 320 mm; Under a pressure of 0.36MPa, the water seepage rate is no more than 1%.

7. A method for constructing a secondary tunnel lining, characterized in that: The mortar aggregate concrete for tunnel secondary lining according to any one of claims 1 to 6 is used, and the construction method comprises the following steps: Step 1: Assemble the integral formwork of the tunnel secondary lining, and preset grouting holes at the bottom of the arch foot on both sides of the tunnel secondary lining formwork, and preset exhaust holes at the top of the formwork; the longitudinal spacing of the grouting holes is 3-6m, and the longitudinal spacing of the exhaust holes is 0.5-1m; Step 2: Filling the secondary tunnel lining template with aggregate to form a skeleton; the aggregate is densely packed by its own weight; Step 3: After the aggregate filling is completed, the grouting holes and 3-5 adjacent vent holes on the same section are opened, and the remaining grouting holes and vent holes are kept closed, and high-fluidity grouting material is poured through the preset grouting holes; Step 4: Pressure-inject high-fluidity grouting material from bottom to top, with the maximum pump pressure not exceeding 2 MPa, until uniform slurry continuously overflows from the exhaust hole, and the injection is completed; Step 5: After the high-fluidity grouting material is poured, the grouting holes and the vent holes are sealed; Step 6: Repeat steps 2 to 5 until the grouting of the mortar-bone aggregate concrete along the entire length of the tunnel is completed. Step 7: After the strength of the tunnel secondary lining mortar-bone polymer concrete meets the requirements, the formwork is removed. After the formwork is removed, the mortar-bone polymer concrete is subjected to moisturizing maintenance to obtain the tunnel secondary lining mortar-bone polymer concrete structure.

8. The construction method according to claim 7, characterized in that: In step 1, the diameter of the grouting hole is 2-5 cm.

9. The construction method according to claim 7, characterized in that: The diameter of the exhaust hole is 5-10 mm.

10. The construction method according to claim 7, characterized in that: In step 7, the curing method is as follows: controlling the humidity of the concrete surface to be above 90%; ensuring that the temperature difference between the interior and surface of the concrete does not exceed 20°C, and the temperature difference between the surface of the concrete and the ambient temperature of the concrete does not exceed 20°C; and the curing time is not less than 14 days.

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