A fast-setting, erosion-resistant, water-rich tunnel shotcrete and its preparation method and application

Abstract

The present invention provides a fast-setting, erosion-resistant water-rich tunnel shotcrete and its preparation method and application, belonging to the technical field of shotcrete. The water-rich tunnel shotcrete provided by the present invention optimizes the composition of ordinary shotcrete, adjusts the dosage of the accelerating agent, adds modified microsilica powder, thickener admixture, and asphalt-based carbon fiber, to form a complete set of technology for fast-setting, early-strength, and low-rebound control of water-rich tunnel shotcrete; at the same time, the accelerating agent is improved, and the dosage of the accelerating agent in the water-rich tunnel shotcrete is controlled, so that the water-rich tunnel shotcrete can have a good prevention and control effect on different types of tunnel water inrush; by optimizing the accelerating agent, the setting time of the water-rich tunnel shotcrete can be greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of shotcrete, and in particular to a fast-setting, scour-resistant, water-rich tunnel shotcrete and a preparation method and application thereof. Background Art

[0002] Affected by geological structure, topography, landform and groundwater characteristics, tunnels are prone to water inrush during construction. Tunnel water inrush is a major difficulty in tunnel construction, which directly affects the construction progress and the life safety of construction personnel, and even has a huge impact on the subsequent commissioning of tunnels. Therefore, solving the problem of tunnel water inrush is a key factor in promoting tunnel construction and development. As the last step of the initial support process, the main function of water-rich tunnel shotcrete is to increase the thickness and strength of the structure and improve the stability and layer capacity of the tunnel. Its early strength (within 24 hours), adhesion, collapse resistance and workability have a great impact on the safety, quality, cost and work efficiency of the tunnel construction period. Its later strength and durability are of great significance to the quality of tunnel operation. The commonly used water-rich tunnel shotcrete has low early strength, large rebound and poor durability, which makes the construction of water-rich tunnel difficult. The adhesion of water-rich tunnel shotcrete to the surrounding rock is very poor. In addition, the cement hydration degree is not high at an early age, and the erosion of groundwater on the initial support concrete will increase exponentially. Due to the serious water gushing phenomenon in the tunnel, the water gushing is in strands and the amount of water gushing is large. In actual on-site application, the rebound rate of ordinary water-rich tunnel shotcrete is generally around 20~30%, so there is a serious waste after spraying. At the same time, under the scouring effect of the gushing water, the water-rich tunnel shotcrete is difficult to adhere closely to the rock mass, and the block falling phenomenon is serious, which cannot meet the on-site requirements. It is still necessary to propose certain technical means to effectively control the rebound rate and scouring resistance of water-rich tunnel shotcrete construction.

[0003] In order to reduce the rebound rate of shotcrete in water-rich tunnels and improve the scouring resistance, relevant research has been conducted in the prior art. For example, Chinese invention patent application CN113511860A discloses a method for reducing the rebound rate by introducing emulsified asphalt into shotcrete in water-rich tunnels. The method achieves control of the rebound rate of shotcrete in water-rich tunnels and improves the bonding force by high-speed stirring of concrete containing emulsified asphalt. However, the amount of emulsified asphalt added to the shotcrete in water-rich tunnels provided by the scheme is large, and 70 to 100 parts of emulsified asphalt are required for 435 parts of cement. The high content of asphalt makes it difficult to disperse the raw materials during the stirring process of shotcrete in water-rich tunnels, making preparation difficult. CN109437722A discloses a low-rebound and high-early-strength wet shotcrete, which controls the rebound rate of shotcrete in water-rich tunnels by introducing high-strength ultrafine admixtures (such as microsilica powder). However, according to the records in Table 3, the rebound rate of the low-rebound and high-early-strength wet shotcrete obtained by the scheme in water-rich areas is still as high as 24.3%, which is difficult to meet the requirements of the prior art.

[0004] Therefore, providing a water-rich tunnel shotcrete with short setting time, low rebound rate and excellent scour resistance has become a technical problem to be solved urgently in the field. Summary of the invention

[0005] The purpose of the present invention is to provide a fast-setting, scour-resistant water-rich tunnel shotcrete and its preparation method and application. The water-rich tunnel shotcrete provided by the present invention has a short setting time and excellent scour resistance. It can play a good preventive effect on tunnel water inrush with strands of water >3cm, tunnel water inrush with strands of water ≤3cm and tunnel water inrush with wetting water flow. At the same time, the rebound rate of the shotcrete is low.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The invention provides a fast-setting, erosion-resistant, water-rich tunnel shotcrete, which comprises the following components by weight: 130-150 parts of water, 350-400 parts of silicate cement, 15-30 parts of sulphoaluminate cement, 50-80 parts of fly ash, 15-30 parts of modified microsilica powder, 50-80 parts of waterborne polyurethane, 900-1100 parts of fine aggregate, 600-700 parts of coarse aggregate, 4-5 parts of water reducer, 30-40 parts of preservative, 150-200 parts of asphalt-based carbon fiber, 0.1-1 parts of thickener and strong accelerating setting agent;

[0008] The composition of the strong accelerator includes a curing agent, an SN (I) accelerator and an alkali-free accelerator, and the composition of the alkali-free accelerator includes: aluminate, phosphotungstate, a low molecular weight polymer, a high molecular weight polymer and water; the mass ratio of the curing agent, the SN (I) accelerator and the alkali-free accelerator is (0.5-0.8):1:(0.5-2); the dosage of the strong accelerator is 6-10% of the total mass of silicate cement, sulphoaluminate cement and fly ash.

[0009] Preferably, the water-rich tunnel shotcrete includes the following ingredients, measured by mass: 146 parts of water, 375 parts of silicate cement, 20 parts of sulphoaluminate cement, 60 parts of fly ash, 20 parts of modified microsilica powder, 60 parts of water-based polyurethane, 998 parts of fine aggregate, 665 parts of coarse aggregate, 4.59 parts of water reducer, 36 parts of preservative, 160 parts of asphalt-based carbon fiber, 0.5 parts of thickener and a strong accelerator.

[0010] Preferably, the tow specification of the asphalt-based carbon fiber is 1K, 3K, 6K or 12K, and the asphalt-based carbon fiber includes asphalt-based carbon fiber with a length of 6 to 10 mm and asphalt-based carbon fiber with a length of 30 to 40 mm.

[0011] Preferably, the composition of the alkali-free accelerator includes, by mass percentage, 15-20% of aluminate, 5-10% of phosphotungstate, 15-25% of low molecular weight polymer, 20-30% of high molecular weight polymer and the balance of water.

[0012] Preferably, the low molecular weight polymer includes any one of polyacrylamide, polymethylbenzenesulfonic acid, polyimide and polydimethyldiallylammonium chloride or a combination thereof, and the molecular weight of the low molecular weight polymer is ≥ 100,000.

[0013] Preferably, the high molecular weight polymer is polyethylene glycol with a molecular weight ≥ 1 million.

[0014] Preferably, the mass ratio of the curing agent, SN (I) accelerator and alkali-free accelerator is (0.6-0.8):1:(1-1.5).

[0015] Preferably, the modified microsilica powder is microsilica powder treated with a silane coupling agent.

[0016] The present invention provides a method for preparing the fast-setting, erosion-resistant, water-rich tunnel shotcrete described in the above technical solution, comprising the following steps:

[0017] (1) Mixing water, modified microsilica fume, waterborne polyurethane, water reducing agent, preservative and thickener to obtain an admixture solution;

[0018] (2) mixing silicate cement, sulphoaluminate cement, fly ash, fine aggregate, coarse aggregate, asphalt-based carbon fiber and the admixture solution obtained in step (1) to obtain concrete to be sprayed;

[0019] (3) The shotcrete obtained in step (2) is mixed with a strong accelerating setting agent to obtain a fast-setting and erosion-resistant water-rich tunnel shotcrete.

[0020] The present invention provides the application of the fast-setting, erosion-resistant, water-rich tunnel shotcrete described in the above technical scheme or the fast-setting, erosion-resistant, water-rich tunnel shotcrete prepared by the preparation method described in the above technical scheme in preventing and controlling water gushing in tunnels.

[0021] The invention provides a fast-setting, erosion-resistant, water-rich tunnel shotcrete, which comprises the following components by weight: 130-150 parts of water, 350-400 parts of silicate cement, 15-30 parts of sulphoaluminate cement, 50-80 parts of fly ash, 15-30 parts of modified microsilica powder, 50-80 parts of waterborne polyurethane, 900-1100 parts of fine aggregate, 600-700 parts of coarse aggregate, 4-5 parts of water reducer, 30-40 parts of preservative, 150-200 parts of asphalt-based carbon fiber, and 100-200 parts of asphalt-based carbon fiber. 0.1-1 part of thickener and strong accelerating setting agent; the composition of the strong accelerating setting agent includes curing agent, SN (I) accelerating setting agent and alkali-free accelerating setting agent, and the composition of the alkali-free accelerating setting agent includes: metaaluminate, phosphotungstate, low molecular weight polymer, high molecular weight polymer and water; the mass ratio of the curing agent, SN (I) accelerating setting agent and alkali-free accelerating setting agent is (0.5-0.8):1:(0.5-2); the dosage of the strong accelerating setting agent is 6-10% of the total mass of silicate cement, sulphoaluminate cement and fly ash.The present invention optimizes the composition of ordinary shotcrete, adjusts the amount of accelerating agent, adds modified microsilica powder, thickener, admixture and asphalt-based carbon fiber, and forms a complete set of technology for controlling rapid setting, early strength and low rebound of shotcrete in water-rich tunnels. The present invention adopts silicate cement as gel material, which can make the shotcrete have high strength in the later stage. However, the setting rate of silicate cement is slow, which is difficult to meet the use requirements of shotcrete in water-rich tunnels. Therefore, a small amount of sulphoaluminate cement is introduced as a stabilizer and accelerator. The addition of sulphoaluminate cement can accelerate the reaction speed of the cementitious material system, control the hydration products such as CSH gel and ettringite, and improve the quality of the shotcrete. The synchronous development of materials, thereby realizing the rapid coagulation of shotcrete, makes the water-rich tunnel shotcrete provided by the present invention have the characteristics of fast coagulation speed, high early strength and excellent 28-day mechanical properties compared with the direct use of sulphoaluminate cement as the gel material; the present invention adds water-based polyurethane to concrete, on the one hand, the water-based polyurethane has a good bonding effect, thereby improving the bonding effect between the raw materials in the concrete, thereby significantly reducing the rebound rate of the concrete, and at the same time improving the early strength of the concrete; on the other hand, the water-based polyurethane has good coagulation after coagulation. The invention adopts asphalt-based carbon fiber as reinforcing material, which can strengthen the shotcrete from two aspects: on the one hand, in the process of concrete spraying, due to the large bonding force between the asphalt-based carbon fiber and the matrix concrete, the external force needs to overcome the bonding force, or the fiber breaks or pulls out, which consumes a lot of fracture energy, thereby reducing the rebound rate of the shotcrete; on the other hand, after the shotcrete solidifies, when the asphalt-based carbon fiber has not been pulled out or broken, due to the presence of the asphalt-based carbon fiber, the concrete will not fall off quickly even if cracks are generated during the scouring process, but new cracks will be generated, so the stress and energy are dispersed on different sections to enhance the ductility of the concrete, so that the concrete with the asphalt-based carbon fiber added shows great scouring resistance, and the fibers are evenly distributed in the concrete, and the pull-out shear stress of the fibers causes a large number of microcracks in the concrete, thereby dispersing and consuming energy and relieving stress concentration; the invention improves the accelerator and controls the amount of the accelerator in the shotcrete, so that the shotcrete can have a good prevention and control effect on different types of tunnel water inrush. The results of the embodiments show that after the water-rich tunnel shotcrete provided by the present invention is stirred, the color is uniform, no segregation and water bleeding are observed, the water-rich tunnel shotcrete has good workability, good cohesion, no water retention, medium stickiness, slump of 200mm, and apparent density of 2420kg / m. 3 . BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1This is a physical picture of the water-rich tunnel shotcrete obtained in Example 1 of the present invention;

[0023] Figure 2 This is a physical picture of the slump test of the water-rich tunnel shotcrete obtained in Example 1 of the present invention;

[0024] Figure 3 A physical picture of the water-rich tunnel shotcrete after solidification provided in Example 1 of the present invention;

[0025] Figure 4 This is a physical picture of the shotcrete after solidification provided in Comparative Example 1. DETAILED DESCRIPTION

[0026] The invention provides a fast-setting, erosion-resistant, water-rich tunnel shotcrete, which comprises the following components, measured by mass: 130-150 parts of water, 350-400 parts of Portland cement, 15-30 parts of sulphoaluminate cement, 50-80 parts of fly ash, 15-30 parts of modified microsilica powder, 50-80 parts of waterborne polyurethane, 900-1100 parts of fine aggregate, 600-700 parts of coarse aggregate, 4-5 parts of water reducer, 30-40 parts of preservative, 150-200 parts of asphalt-based carbon fiber, 0.1-1 part of thickener and a strong accelerating setting agent.

[0027] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known to those skilled in the art.

[0028] Calculated by weight, the fast-setting, erosion-resistant, water-rich tunnel shotcrete provided by the present invention includes 130 to 150 parts of water, preferably 135 to 150 parts, and more preferably 140 to 146 parts.

[0029] Based on the mass fraction of water being 130-150 parts, the fast-setting, erosion-resistant, water-rich tunnel shotcrete provided by the present invention also includes 350-400 parts of silicate cement, preferably 375-380 parts. In the present invention, the silicate cement is preferably PO 42.5 grade ordinary silicate cement. In one embodiment of the present invention, the technical indicators of the silicate cement are: stability 0.5mm, 3d flexural strength 5.5MPa, 28d flexural strength 7.8MPa, 3d compressive strength 27.0MPa, 28d compressive strength 46.4MPa.

[0030] Based on the mass fraction of water being 130 to 150 parts, the fast-setting, erosion-resistant, water-rich tunnel shotcrete provided by the present invention also includes 15 to 30 parts of sulphoaluminate cement, preferably 20 to 25 parts. In the present invention, the sulphoaluminate cement is preferably 42.5-grade sulphoaluminate cement or 52.5-grade sulphoaluminate cement, more preferably 42.5-grade sulphoaluminate cement. The present invention introduces a small amount of sulphoaluminate cement as a stabilizer and accelerator. The addition of sulphoaluminate cement can accelerate the reaction speed of the cementitious material system, control the synchronous development of hydration products such as CSH gel and calcium sulfonate, thereby achieving rapid setting of shotcrete. However, compared with directly using sulphoaluminate cement as a gel material, the shotcrete prepared by adding a small amount of sulphoaluminate cement has the characteristics of fast setting speed, high early strength and excellent 28-day mechanical properties.

[0031] Based on the mass fraction of water being 130-150 parts, the fast-setting, erosion-resistant water-rich tunnel shotcrete provided by the present invention also includes 50-80 parts of fly ash, preferably 60-70 parts. In the present invention, the fly ash is preferably Class F II fly ash. In one embodiment of the present invention, the technical indicators of the fly ash are: ignition loss 3.6%, water content 0.5%, water requirement ratio 100%, activity index (28d) 78%, fineness content 21.0%, sulfur trioxide content 0.76%, free calcium oxide content 0.64%, alkali content 0.66%, chloride ion 0.033%. The present invention adds fly ash to the water-rich tunnel shotcrete, which can play a certain activity effect on the one hand, and on the other hand, the fly ash can play a filling effect and improve the structural density. At the same time, the fly ash can improve the fluidity, later strength and durability of the concrete.

[0032] Calculated based on 130 to 150 parts by mass of water, the fast-setting, erosion-resistant, water-rich tunnel shotcrete provided by the present invention also includes 15 to 30 parts of modified microsilica powder, preferably 20 to 25 parts. In the present invention, the modified microsilica powder is preferably microsilica powder treated with a silane coupling agent; the preparation method of the modified microsilica powder is: soaking the microsilica powder in a silane coupling agent solution with a concentration of 1 to 2wt.% for 10 to 30 minutes, and then filtering and drying in sequence to obtain the modified microsilica powder. In one embodiment of the present invention, the technical indicators of the microsilica powder are: SiO2 content 95.49wt.%, water requirement ratio 106%, water content 1.7%, specific surface area 22475m 2 / kg, activity index 118%, loss on ignition 1.9%, Cl - Content 0.004%, apparent density 27000kg / m 3The present invention improves the dispersibility of microsilica powder by modifying the microsilica powder, so that the microsilica powder can be evenly dispersed in the water-rich tunnel shotcrete, thereby improving the early strength of the water-rich tunnel shotcrete and reducing the rebound rate.

[0033] The fast-setting, scour-resistant, water-rich tunnel shotcrete provided by the present invention also includes 50 to 80 parts of water-based polyurethane, preferably 60 parts, based on 130 to 150 parts by mass of water. In the present invention, the water-based polyurethane is preferably S339A, S339B, H39, H40 or H34A produced by Wengkaier Company. The present invention adds water-based polyurethane to concrete. On the one hand, the water-based polyurethane has a good bonding effect, thereby improving the bonding effect between the raw materials in the concrete, thereby significantly reducing the rebound rate of the concrete and improving the early strength of the concrete. On the other hand, the water-based polyurethane has good water washing fastness after condensation, and can play a good protective effect even if it is scour by water.

[0034] Based on the mass fraction of water being 130-150 parts, the fast-setting, erosion-resistant, water-rich tunnel shotcrete provided by the present invention also includes 600-700 parts of coarse aggregate, preferably 650-665 parts. In the present invention, the coarse aggregate is preferably crushed stone with a particle size of 5mm-10mm. In one embodiment of the present invention, the technical indicators of the crushed stone are: mud content 0.0%, needle-like particle content 6.2%, apparent density 2694kg / m 3 , mud content 0.6%, water absorption rate 0.14%, porosity 42.8%. The present invention can form a dense skeleton structure by using the crushed stone of the above particle size as coarse aggregate, thereby improving the mechanical properties of the water-rich tunnel shotcrete.

[0035] Based on the mass fraction of water being 130-150 parts, the fast-setting, erosion-resistant, water-rich tunnel shotcrete provided by the present invention also includes 900-1100 parts of fine aggregate, preferably 950-1050 parts, and more preferably 998 parts. In the present invention, the fine aggregate is preferably machine-made sand with a particle size of ≤4.75 mm. In one embodiment of the present invention, the technical indicators of the machine-made sand are: mud content 0.2%, methylene blue MBV 0.8 g / kg, apparent density 2660 kg / m 3 , stone powder content 5.7%, crushing value 16%, bulk density 1627kg / m 3 , the void ratio is 38.8%. The present invention can fill the voids formed between the coarse aggregates by adding fine aggregates, thereby further improving the compactness of the water-rich tunnel shotcrete.

[0036] Based on the mass fraction of water being 130 to 150 parts, the fast-setting, erosion-resistant, water-rich tunnel shotcrete provided by the present invention also includes 4 to 5 parts of a water reducer, preferably 4.5 to 4.59 parts. In the present invention, the water reducer is preferably a KDSP polycarboxylic acid high-energy water reducer. In one embodiment of the present invention, the technical indicators of the water reducer are: water reduction rate 28%, air content 3.1%, slump change over time of 1h 59mm, 3d compressive strength ratio 167%, 28d compressive strength ratio 148%, 28d shrinkage ratio 99%, solid content 22.20%, Cl - The content is 0.064% and the total alkali content is 2.48%. The present invention can improve the fluidity of concrete and the stability of the structure by adding a water reducing agent, thereby improving the strength of the water-rich tunnel shotcrete.

[0037] Based on the mass fraction of water being 130 to 150 parts, the fast-setting, erosion-resistant, water-rich tunnel shotcrete provided by the present invention further comprises 30 to 40 parts of an antiseptic, preferably 35 to 36 parts. In the present invention, the antiseptic is preferably a KD-9 antiseptic. In one embodiment of the present invention, the technical indicators of the antiseptic are: 7d compressive strength ratio 95%, 28d compressive strength ratio 106%, solid content 14.41%, Cl - The content is 0.025%, and the total alkali content is 0.50%. The present invention can effectively improve the corrosion resistance and alkali-aggregate reaction resistance of water-rich tunnel shotcrete by adding preservatives, thereby improving the structural durability of the concrete.

[0038] Based on the mass fraction of water being 130 to 150 parts, the fast-setting, erosion-resistant, water-rich tunnel shotcrete provided by the present invention also includes 150 to 200 parts of asphalt-based carbon fibers, preferably 160 to 200 parts, and more preferably 170 to 180 parts. In the present invention, the tow specification of the asphalt-based carbon fibers is preferably 1K, 3K, 6K or 12K, and more preferably 3K, 6K or 12K; the asphalt-based carbon fibers preferably include asphalt-based carbon fibers with a length of 6 to 10 mm and asphalt-based carbon fibers with a length of 30 to 40 mm; the mass ratio of the asphalt-based carbon fibers with a length of 6 to 10 mm and the asphalt-based carbon fibers with a length of 30 to 40 mm is preferably 1: (1 to 5), and more preferably 1: (3 to 5). The present invention introduces asphalt-based carbon fibers into the shotcrete of the water-rich tunnel. Compared with traditional polypropylene fibers, the asphalt-based carbon fibers have higher tensile strength and elastic modulus, which can further improve the anti-cracking performance and scouring resistance of the shotcrete. Since the asphalt-based carbon fibers contain two different sizes, they can be staggered in the shotcrete of the water-rich tunnel, which can play a good synergistic role. On the one hand, it can make the bonding performance between materials better, thereby reducing the rebound rate of the shotcrete of the water-rich tunnel during use; on the other hand, it can further improve the anti-cracking performance and scouring resistance of the concrete, so that the shotcrete of the water-rich tunnel can still be closely attached to the rock mass even in the case of large water gushing.

[0039] Based on the mass fraction of water being 130 to 150 parts, the fast-setting, erosion-resistant water-rich tunnel shotcrete provided by the present invention also includes 0.1 to 1 part of a thickener, preferably 0.5 part. In the present invention, the thickener is preferably an L-210 thickener. In one embodiment of the present invention, the technical indicators of the thickener are: molecular weight 18 million, hydrolysis degree 25%, solid content 90.15%, water solubility time 1.5h, pH value 7 to 9. By adding a thickener to the water-rich tunnel shotcrete, the present invention can adjust the rheology of the concrete and avoid problems such as splashing during use.

[0040] The fast-setting, erosion-resistant, water-rich tunnel shotcrete provided by the present invention also includes a strong accelerating setting agent. In the present invention, the composition of the strong accelerating setting agent includes a curing agent, an SN (I) accelerating setting agent and an alkali-free accelerating setting agent; the mass ratio of the curing agent, the SN (I) accelerating setting agent and the alkali-free accelerating setting agent is (0.5-0.8):1:(0.5-2), preferably (0.6-0.8):1:(1-1.5), and more preferably 0.8:1:1.5.

[0041] In the present invention, the curing agent is preferably ethylene glycol or propylene glycol. In the present invention, the curing agent can promote the curing of waterborne polyurethane, thereby further improving the mechanical properties of concrete.

[0042] In the present invention, the technical indicators of the SN (I) quick-setting agent are: initial setting time 2 minutes and 40 seconds, final setting time 11 minutes and 56 seconds, compressive strength 9.8 MPa, and 28d compressive strength ratio 82%.

[0043] In the present invention, the composition of the alkali-free accelerator includes: metaaluminate, phosphotungstate, low molecular weight polymer, high molecular weight polymer and water. In the present invention, the composition of the alkali-free accelerator is preferably 15-20% of metaaluminate, 5-10% of phosphotungstate, 15-25% of low molecular weight polymer, 20-30% of high molecular weight polymer and the balance of water, and more preferably 15% of metaaluminate, 8-10% of phosphotungstate, 18-20% of low molecular weight polymer, 25-28% of high molecular weight polymer and the balance of water. In the present invention, the low molecular weight polymer preferably includes any one or a combination of several of polyacrylamide, polymethylbenzenesulfonic acid, polyimide and polydimethyldiallylammonium chloride, and more preferably polyacrylamide or polyimide; the molecular weight of the low molecular weight polymer is preferably ≥100,000, and more preferably 100,000-200,000. In the present invention, the high molecular weight polymer is preferably polyethylene glycol with a molecular weight ≥1 million, and more preferably polyethylene glycol with a molecular weight of 1 million-1.5 million. In the present invention, the metaaluminate is preferably sodium metaaluminate; the phosphotungstate is preferably sodium phosphotungstate. The present invention increases the content of aluminum ions in the accelerator by introducing amorphous aluminum hydroxide using metaaluminate; the use of phosphotungstate introduces phosphorus and tungsten atoms with larger atomic radius, and the chemical imbalance caused can make gypsum and C3A (tricalcium aluminate) more easily soluble, thereby promoting the early generation of a large amount of calcium sulfonate, thereby further improving the effect of rapid setting; the use of low molecular weight polymers and high molecular weight polymers with different molecular weights for grading can effectively improve the accelerating coagulation and early strength performance of the accelerator, so as to improve the bonding force between the water-rich tunnel shotcrete and the substrate, and reduce the rebound rate of the water-rich tunnel shotcrete.

[0044] In the present invention, the dosage of the strong accelerator is 6-10% of the total mass of silicate cement, sulfoaluminate cement and fly ash. In the present invention, the dosage of the strong accelerator is preferably adjusted according to the amount of water when the tunnel is gushing; when the tunnel gushing is a wetting water flow, the dosage of the strong accelerator in the water-rich tunnel shotcrete is 6-8% of the total mass of silicate cement, sulfoaluminate cement and fly ash; when the tunnel gushing is a strand of water, the dosage of the strong accelerator in the water-rich tunnel shotcrete is preferably 8-10% of the total mass of silicate cement, sulfoaluminate cement and fly ash. In the present invention, when the diameter of the strand of water is ≤3cm, the water-rich tunnel shotcrete can be sprayed on the surface of the strand of water in a manner well known to those skilled in the art. In the present invention, when the diameter of the strand of water is >3cm, it is preferred to first use a fine drainage method to make the diameter of the strand of water ≤3cm, and then spray the water-rich tunnel shotcrete on the surface of the strand of water; the fine drainage is preferably drained in a pipeline. The present invention can achieve good prevention and control effects for different tunnel water gushing situations by controlling the dosage of the accelerating setting agent.

[0045] The present invention optimizes the composition of ordinary shotcrete, adjusts the amount of accelerating agent, adds modified microsilica powder, thickener, admixture and asphalt-based carbon fiber, thus forming a complete set of technology for fast-setting, early-strength and low-rebound control of water-rich tunnel shotcrete; by adding water-based polyurethane to concrete, on the one hand, the water-based polyurethane has a good bonding effect, thereby improving the bonding effect between the raw materials in the concrete, thereby significantly reducing the rebound rate of the concrete and improving the early strength of the concrete; on the other hand, the water-based polyurethane has good water washing fastness after coagulation, and can play a good protective effect even if it is washed by water; by using asphalt-based carbon fiber as a reinforcing material, the shotcrete can be strengthened in two aspects: on the one hand, during the concrete spraying process, due to the large bonding force between the asphalt-based carbon fiber and the base concrete, the external force needs to overcome the bonding force, Or the fiber may break or be pulled out, which consumes a lot of fracture energy, thereby reducing the rebound rate of shotcrete; on the other hand, after the shotcrete solidifies, when the asphalt-based carbon fiber has not been pulled out or broken, due to the presence of the asphalt-based carbon fiber, the concrete will not fall off quickly even if cracks occur during the scouring process, but new cracks will be generated. Therefore, the stress and energy are dispersed on different sections to enhance the ductility of the concrete, so that the concrete with the addition of asphalt-based carbon fiber exhibits great scouring resistance. In addition, the fibers are evenly distributed in the concrete, and the pull-out shear stress of the fibers causes a large number of microcracks in the concrete, thereby dispersing and consuming energy and alleviating stress concentration; at the same time, improving the accelerator and controlling the amount of the accelerator in the shotcrete can make the shotcrete have a good prevention and control effect on different types of tunnel water gushing.

[0046] The present invention also provides a method for preparing the fast-setting, erosion-resistant, water-rich tunnel shotcrete described in the above technical solution, comprising the following steps:

[0047] (1) Mixing water, modified microsilica fume, waterborne polyurethane, water reducing agent, preservative and thickener to obtain an admixture solution;

[0048] (2) mixing silicate cement, sulphoaluminate cement, fly ash, fine aggregate, coarse aggregate, asphalt-based carbon fiber and the admixture solution obtained in step (1) to obtain concrete to be sprayed;

[0049] (3) The shotcrete obtained in step (2) is mixed with a strong accelerating setting agent to obtain a fast-setting and erosion-resistant water-rich tunnel shotcrete.

[0050] The present invention mixes water, modified microsilica powder, waterborne polyurethane, a water reducing agent, a preservative and a thickener to obtain an additive solution. The present invention has no particular limitation on the specific manner of the mixing, and any mixing method well known to those skilled in the art can be used.

[0051] After obtaining the admixture solution, the present invention mixes silicate cement, sulphoaluminate cement, fly ash, fine aggregate, coarse aggregate, asphalt-based carbon fiber and the admixture solution to obtain concrete to be sprayed.

[0052] The present invention can make the raw materials mixed more evenly by adopting the above-mentioned mixing method, thereby further improving the mechanical properties of the water-rich tunnel shotcrete.

[0053] After obtaining the concrete to be sprayed, the present invention mixes the concrete to be sprayed with a strong accelerating setting agent to obtain the fast-setting, scour-resistant and water-rich tunnel sprayed concrete.

[0054] The invention adds the strong accelerating setting agent to the concrete last, thus preventing the concrete from solidifying in the spraying device due to the strong accelerating setting agent being added too early.

[0055] The preparation method provided by the present invention is simple and can be constructed on site, thus facilitating the control of the setting time of concrete; after the concrete to be sprayed and the strong accelerating setting agent are mixed to obtain the water-rich tunnel sprayed concrete, the water-rich tunnel sprayed concrete should be sprayed as soon as possible.

[0056] The present invention also provides the use of the fast-setting, erosion-resistant, water-rich tunnel shotcrete described in the above technical scheme or the fast-setting, erosion-resistant, water-rich tunnel shotcrete prepared by the preparation method described in the above technical scheme in preventing and controlling tunnel water inrush.

[0057] In the present invention, when the tunnel water gushing is an infiltration-like water flow or a strand-like water with a diameter of ≤3cm, the fast-setting, erosion-resistant, water-rich tunnel shotcrete can be sprayed on the surface of the strand-like water in a manner well known to those skilled in the art. In the present invention, when the tunnel water gushing is a strand-like water with a diameter of >3cm, it is preferred to first use a fine drainage method to make the diameter of the strand-like water ≤3cm, and then spray the fast-setting, erosion-resistant, water-rich tunnel shotcrete on the surface of the strand-like water; the fine drainage is preferably carried out by means of a pipeline. The present invention can further improve the bonding strength between the water-rich tunnel shotcrete and the rock mass by using the above-mentioned method to apply the water-rich tunnel shotcrete.

[0058] The present invention adjusts the dosage of the accelerating setting agent in the water-rich tunnel shotcrete according to different types of tunnel water gushing, so that the water-rich tunnel shotcrete can be closely attached to the rock mass without falling off, and will not be dispersed due to the scouring effect of the water flow before solidification.

[0059] The present invention has no special limitation on the specific operation of spraying the fast-setting, erosion-resistant, water-rich tunnel shotcrete, and the spraying process well known to those skilled in the art can be adopted.

[0060] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] Example 1

[0062] A fast-setting, scour-resistant, water-rich tunnel shotcrete, composed of the following components by mass: 146 parts of water, 375 parts of silicate cement, 20 parts of sulphoaluminate cement, 60 parts of fly ash, 20 parts of modified microsilica powder, 60 parts of waterborne polyurethane, 998 parts of fine aggregate, 665 parts of coarse aggregate, 4.59 parts of water reducer, 36 parts of preservative, 160 parts of asphalt-based carbon fiber, 0.5 parts of thickener and strong accelerating setting agent;

[0063] The cement is ordinary Portland cement with a PO 42.5 grade; the fly ash is Class F II fly ash; the preparation method of the modified microsilica powder is: soak the microsilica powder in a silane coupling agent solution with a concentration of 1.5wt.% for 130 minutes, and then filter and dry in sequence to obtain the modified microsilica powder; the water-based polyurethane is S339B produced by Wengkaier Company; the coarse aggregate is crushed stone with a particle size of 5-10mm; the fine aggregate is machine-made sand with a particle size of ≤4.75mm; the water reducer is KDSP polycarboxylic acid high-energy water reducer; the preservative is KD-9 preservative; the tow specification of the asphalt-based carbon fiber is 6K, the asphalt-based carbon fiber is an asphalt-based carbon fiber with a length of 6-10mm and an asphalt-based carbon fiber with a length of 30-40mm, and the mass ratio of the asphalt-based carbon fiber with a length of 6-10mm to the asphalt-based carbon fiber with a length of 30-40mm is 1:3; the thickener is L-210 thickener;

[0064] The composition of the strong accelerating setting agent is a curing agent, an SN (I) accelerating setting agent and an alkali-free accelerating setting agent, wherein the mass ratio of the SN (I) accelerating setting agent to the alkali-free accelerating setting agent is 0.6:1:1.2; the dosage of the strong accelerating setting agent is 6% of the total mass of silicate cement, sulphoaluminate cement and fly ash; the curing agent is ethylene glycol;

[0065] The composition of the alkali-free accelerator is 15% sodium aluminate, 8% sodium phosphotungstate, 20% low molecular weight polymer, 25% high molecular weight polymer and the balance water by mass percentage; the low molecular weight polymer is polyacrylamide with a molecular weight of ≥100,000; the high molecular weight polymer is polyethylene glycol with a molecular weight of ≥1,000,000;

[0066] The method for preparing the fast-setting, erosion-resistant, water-rich tunnel shotcrete comprises the following steps:

[0067] (1) Mix water, modified microsilica powder, water-based polyurethane, water reducer, preservative and thickener and stir for 30 minutes to obtain an admixture solution;

[0068] (2) mixing cement, fly ash, fine aggregate, coarse aggregate, asphalt-based carbon fiber and the admixture solution obtained in step (1) to obtain concrete to be sprayed;

[0069] (3) The shotcrete obtained in step (2) is mixed with a strong accelerating setting agent to obtain a fast-setting and erosion-resistant water-rich tunnel shotcrete.

[0070] The actual picture of the water-rich tunnel shotcrete obtained in Example 1 of the present invention is as follows Figure 1 As shown. Figure 1 It can be seen that after the water-rich tunnel shotcrete is mixed, the color is uniform, no segregation or water seepage is observed, and the workability of the water-rich tunnel shotcrete is good.

[0071] The actual picture of the slump test of the water-rich tunnel shotcrete obtained in Example 1 of the present invention is as follows Figure 2 As shown. Figure 2 It can be seen that the water-rich tunnel shotcrete obtained by the present invention has good cohesiveness, no water retention, medium stickiness and slump of 200 mm.

[0072] The apparent density of the water-rich tunnel shotcrete obtained in Example 1 of the present invention was tested, and the results showed that the apparent density of the water-rich tunnel shotcrete obtained in Example 1 was 2420 kg / m 3 .

[0073] The actual picture of the water-rich tunnel shotcrete after solidification provided by Example 1 of the present invention is as follows Figure 3 As shown. Figure 3 It can be seen that the water-rich tunnel shotcrete provided by the present invention has no cracking phenomenon as a whole after solidification and has a stable structure.

[0074] Example 2

[0075] The dosage of the strong accelerating setting agent is 8% of the total mass of silicate cement, sulphoaluminate cement and fly ash, and other conditions are the same as those in Example 1.

[0076] Example 3

[0077] The dosage of the strong accelerating setting agent is 10% of the total mass of silicate cement, sulphoaluminate cement and fly ash, and other conditions are the same as those in Example 1.

[0078] Example 4

[0079] The mass ratio of the curing agent, SN (I) accelerator and alkali-free accelerator is 0.6:1:0.5, and other conditions are the same as those in Example 1.

[0080] Example 5

[0081] The mass ratio of the curing agent, SN (I) accelerator and alkali-free accelerator is 0.6:1:1.0, and other conditions are the same as those in Example 1.

[0082] Example 6

[0083] The mass ratio of the curing agent, SN (I) accelerator and alkali-free accelerator is 0.6:1:1.5, and other conditions are the same as those in Example 1.

[0084] Example 7

[0085] The mass ratio of the curing agent, SN (I) accelerator and alkali-free accelerator is 0.6:1:2.0, and other conditions are the same as those in Example 1.

[0086] Example 8

[0087] The aqueous polyurethane was 70 parts, and other conditions were the same as those in Example 1.

[0088] Example 9

[0089] The aqueous polyurethane was 80 parts, and other conditions were the same as those in Example 1.

[0090] Example 10

[0091] The sulphoaluminate cement is 30 parts, and other conditions are the same as those in Example 1.

[0092] Comparative Example 1

[0093] The strong accelerating setting agent was replaced by sodium aluminate, and other conditions were the same as those in Example 1.

[0094] Comparative Example 2

[0095] The strong accelerating setting agent was replaced by SN (I) accelerating setting agent, and other conditions were the same as those in Example 1.

[0096] Comparative Example 3

[0097] The strong accelerating setting agent was replaced by an alkali-free accelerating setting agent, and other conditions were the same as those in Example 1.

[0098] Comparative Example 4

[0099] The dosage of the strong accelerating setting agent is 2% of the total mass of silicate cement, sulphoaluminate cement and fly ash, and other conditions are the same as those in Example 1.

[0100] Comparative Example 5

[0101] The dosage of the strong accelerating setting agent is 4% of the total mass of silicate cement, sulphoaluminate cement and fly ash, and other conditions are the same as those in Example 1.

[0102] Comparative Example 6

[0103] No waterborne polyurethane was added, and other conditions were the same as in Example 1.

[0104] Comparative Example 7

[0105] The dosage of the waterborne polyurethane is 20 parts, and other conditions are the same as those in Example 1.

[0106] Comparative Example 8

[0107] The asphalt-based carbon fiber was replaced with polypropylene fiber, and other conditions were the same as those in Example 1.

[0108] Comparative Example 9

[0109] The sulphoaluminate cement was omitted, and other conditions were the same as those in Example 1.

[0110] Comparative Example 10

[0111] A water-rich tunnel shotcrete consists of the following ingredients, measured by mass: 146 parts of water, 375 parts of sulphoaluminate cement, 60 parts of fly ash, 20 parts of modified microsilica powder, 60 parts of water-based polyurethane, 998 parts of fine aggregate, 665 parts of coarse aggregate, 4.59 parts of water reducer, 36 parts of preservative, 160 parts of asphalt-based carbon fiber, 0.5 parts of thickener and a strong accelerator.

[0112] The actual picture of the shotcrete after solidification provided in Comparative Example 1 is as follows Figure 4 As shown. Figure 4 It can be seen that the sprayed concrete provided in the comparative example is unstable and fragile after solidification.

[0113] The performance of the shotcrete provided by Examples 1 to 10 and Comparative Examples 1 to 10 was tested, and the results are shown in Table 1:

[0114] Table 1 Performance of shotcrete provided by Examples 1 to 10 and Comparative Examples 1 to 10

[0115]

[0116] In Table 1, the initial setting time and final setting time are tested by using a penetration resistance meter, where the initial setting time is the time when the penetration resistance is 3.5MPa, and the final setting time is the time when the penetration resistance is 28MPa; the compressive strength test is carried out in accordance with relevant standards. This test is carried out in accordance with GB / T50081-2002 "Standard for Test Methods for Building Materials".

[0117] It can be seen from Table 1 that with the adjustment of the components and dosage in the shotcrete, the setting rate and mechanical properties of the shotcrete change significantly; it can be seen from Examples 1 to 3 and Comparative Examples 4 to 5 that with the increase of the dosage of the strong accelerating setting agent in the shotcrete, the initial setting time and the final setting time of the shotcrete are reduced, indicating that the strong accelerating setting agent provided by the present invention can accelerate the solidification of the shotcrete; it can be seen from Examples 1 and 4 to 7 that with the increase of the dosage of the alkali-free accelerating setting agent in the strong accelerating setting agent, the setting time of the shotcrete first decreases and then tends to be stable, indicating that appropriately increasing the dosage of the alkali-free accelerating setting agent in the strong accelerating setting agent can effectively improve the strong accelerating setting agent. The quick-setting effect of the effective accelerating setting agent can be obtained by comparing Example 1, Examples 8-9 and Comparative Example 7. It can be seen that the addition of waterborne polyurethane and the control of its dosage can slightly improve the early strength of concrete. It can be seen from the comparison of Example 1, Example 10 and Comparative Examples 9-10 that by adding a small amount of sulphoaluminate cement to silicate cement, the hydration rate of silicate cement can be greatly improved, thereby reducing the initial setting and final setting time, and improving the early strength of concrete. Although the use of all sulphoaluminate cement in Comparative Example 10 can improve the strength of concrete at an early stage, it can be seen from Table 2 that the late strength of the shotcrete prepared in this way is relatively low.

[0118] The compressive strength of the shotcrete prepared in Examples 1 to 10 and Comparative Examples 1 to 10 was tested, and the results are shown in Table 2:

[0119] Table 2 Compressive strength of shotcrete prepared in Examples 1 to 10 and Comparative Examples 1 to 10

[0120]

[0121] It can be seen from Table 2 that with the adjustment of the components and dosage in the shotcrete, the mechanical properties of the shotcrete change significantly; it can be seen from Examples 1 to 3 and Comparative Examples 4 to 5 that with the increase of the amount of the strong accelerating setting agent in the shotcrete, the compressive strength of the shotcrete at different times will change slightly, indicating that the strong accelerating setting agent provided by the present invention can accelerate the solidification of the shotcrete; it can be seen from Examples 1 and 4 to 7 that with the increase of the amount of the alkali-free accelerating setting agent in the strong accelerating setting agent, the compressive strength of the shotcrete will be adjusted slightly, indicating that the alkali-free accelerating setting agent The adjustment of the dosage can regulate the mechanical properties of concrete; by comparing Example 1, Examples 8-9 and Comparative Example 7, it can be seen that adding waterborne polyurethane and controlling its dosage can slightly improve the early strength of concrete; by comparing Example 1, Example 10 and Comparative Examples 9-10, it can be seen that by adding a small amount of sulphoaluminate cement to silicate cement, it will not have much effect on the later strength of shotcrete, and although the use of all sulphoaluminate cement in Comparative Example 10 can improve the strength of concrete in the early stage, the later strength of the shotcrete is much lower than that of Example 1.

[0122] The rebound rates of the shotcrete prepared in Examples 1 to 10 and Comparative Examples 1 to 10 were tested, and the results are shown in Table 3:

[0123] Table 3 Resilience of shotcrete prepared in Examples 1 to 10 and Comparative Examples 1 to 10

[0124]

[0125] It can be seen from Table 3 that the rebound rate of the shotcrete provided by the present invention is less than 2.5% when there is no gushing water, and the rebound rate is less than 9% when the gushing water is a wetting water flow, and the rebound rate is less than 15% when the gushing water is a strand of water with a diameter of 2 cm; it can be seen from the comparison between the embodiment and comparative examples 6-7 that the present invention can significantly reduce the rebound rate of the shotcrete by adding water-based polyurethane to the shotcrete.

[0126] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A fast-setting, erosion-resistant, water-rich tunnel shotcrete, comprising the following components in parts by mass: 130-150 parts of water, 350-400 parts of Portland cement, 15-30 parts of sulphoaluminate cement, 50-80 parts of fly ash, 15-30 parts of modified microsilica fume, 50-80 parts of waterborne polyurethane, 900-1100 parts of fine aggregate, 600-700 parts of coarse aggregate, 4-5 parts of water reducer, 30-40 parts of preservative, 150-200 parts of asphalt-based carbon fiber, 0.1-1 parts of thickener and strong accelerator; The composition of the strong accelerator includes a curing agent, an SN (I) accelerator and an alkali-free accelerator, wherein the composition of the alkali-free accelerator includes: aluminate, phosphotungstate, low molecular weight polymer, high molecular weight polymer and water; the mass ratio of the curing agent, the SN (I) accelerator and the alkali-free accelerator is (0.5-0.8):1:(0.5-2); the dosage of the strong accelerator is 6-10% of the total mass of silicate cement, sulfoaluminate cement and fly ash; the composition of the alkali-free accelerator includes: 15-20% of aluminate, 5-10% of phosphotungstate, 15-25% of low molecular weight polymer, 20-30% of high molecular weight polymer and the balance of water; the curing agent is ethylene glycol or propylene glycol; the technical indicators of the SN (I) accelerator are: initial setting time 2 minutes and 40 seconds, final setting time 11 minutes and 56 seconds, compressive strength 9.8MPa, 28d compressive strength ratio 82%; The tow specifications of the asphalt-based carbon fiber are 1K, 3K, 6K or 12K, and the asphalt-based carbon fiber includes an asphalt-based carbon fiber with a length of 6 to 10 mm and an asphalt-based carbon fiber with a length of 30 to 40 mm; The low molecular weight polymer includes any one or a combination of polyacrylamide, polymethylbenzenesulfonic acid, polyimide and polydimethyldiallylammonium chloride, and the molecular weight of the low molecular weight polymer is ≥ 100,000; The high molecular weight polymer is polyethylene glycol with a molecular weight ≥ 1 million; The modified microsilica powder is microsilica powder treated with a silane coupling agent.

2. The water-rich tunnel shotcrete according to claim 1 is characterized in that: Calculated by mass, it includes the following ingredients: 146 parts of water, 375 parts of silicate cement, 20 parts of sulphoaluminate cement, 60 parts of fly ash, 20 parts of modified microsilica fume, 60 parts of water-based polyurethane, 998 parts of fine aggregate, 665 parts of coarse aggregate, 4.59 parts of water reducer, 36 parts of preservative, 160 parts of asphalt-based carbon fiber, 0.5 parts of thickener and a strong accelerator.

3. The water-rich tunnel shotcrete according to claim 1, characterized in that: The mass ratio of the curing agent, SN (I) accelerator and alkali-free accelerator is (0.6-0.8):1:(1-1.5).

4. The method for preparing the fast-setting, erosion-resistant, water-rich tunnel shotcrete according to any one of claims 1 to 3, comprising the following steps: (1) Mixing water, modified microsilica fume, waterborne polyurethane, water reducing agent, preservative and thickener to obtain an admixture solution; (2) mixing silicate cement, sulphoaluminate cement, fly ash, fine aggregate, coarse aggregate, asphalt-based carbon fiber and the admixture solution obtained in step (1) to obtain concrete to be sprayed; (3) The shotcrete obtained in step (2) is mixed with a strong accelerating setting agent to obtain a fast-setting and erosion-resistant water-rich tunnel shotcrete.

5. Use of the fast-setting, erosion-resistant, water-rich tunnel shotcrete according to any one of claims 1 to 3 or the fast-setting, erosion-resistant, water-rich tunnel shotcrete prepared by the preparation method according to claim 4 in preventing and controlling water inrush in tunnels.

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