Pre-mixed high-density shrinkage-compensating wet-sprayed concrete yield shear stress regulation method

Abstract

The application discloses a pre-mixed high-density compensation shrinkage wet spraying concrete yield shear stress regulation method and relates to the technical field of wet spraying concrete of hydraulic underground caverns, which comprises the following steps: S1, determining a yield shear stress target value τ0,targ in advance; and S2, according to the design strength and the slump, initially selecting the high-density compensation shrinkage wet spraying concrete water-binder ratio W / B, the cement mass mc, the silica fume mass msi, the expansive agent mass mexp, the water consumption mw, the water reducing agent mass mwr, the saturated surface dry state aggregate total mass ma and the mass fraction mPa,i of each particle size aggregate mixing ratio parameters. The application solves the wet spraying concrete mixing ratio production regulation and control problem oriented by the yield shear stress in the wet spraying construction process, realizes the wet spraying concrete production mixing ratio optimization adjustment based on the target yield shear stress, significantly reduces the rebound rate and the pipe blocking probability, and has obvious economic and social benefits.

Description

Technical Field

[0001] This invention relates to the field of wet sprayed concrete technology for underground caverns in hydraulic engineering, specifically to a method for controlling the yield shear stress of premixed high-density compensating shrinkage wet sprayed concrete. Background Technology

[0002] Wet-mixed shotcrete is one of the most important support materials for hydraulic tunnels. Its workability includes both sprayability and pumpability, with rebound rate being a crucial indicator of sprayability. Research has found that using yield shear stress to characterize sprayability has good technical results. Higher yield shear stress results in lower rebound rate, while lower yield shear stress leads to higher rebound rate. Rebound rate reflects the proportion of rebound material during wet-mixed shotcrete application. A higher rebound rate means more rebound material, greater economic losses, higher dust concentrations, and greater health risks to workers, resulting in poorer economic and social benefits. However, excessively high yield shear stress can conversely reduce pumpability and increase the probability of pipe blockage during spraying. Therefore, it is necessary to use concrete mixtures with moderate yield shear stress for production and spraying.

[0003] Existing yield shear stress results are mainly used for scientific research, revealing the reasons for high and low concrete rebound rates, or assessing the impact of different mix proportion parameters on rebound rates. Commercially available concrete rheometers are expensive, the testing process is cumbersome, and adjusting concrete production mix proportions based on real-time feedback from test results is impractical, with long testing cycles and high costs, hindering widespread application. According to incomplete statistics, there are no real-world cases of using yield shear stress to guide on-site construction of wet-mix shotcrete. High-density, shrinkage-compensating wet-mix shotcrete is a key building material for future implementation of permanent wet-mix shotcrete support and the elimination of secondary lining. Low rebound rate and low pipe blockage probability are two major technical guarantees for the efficient construction of permanent support using high-density, shrinkage-compensating wet-mix shotcrete. New building materials and new support structure types have new demands for reducing rebound rate and pipe blockage probability; a suitable yield shear stress in the mixture has become almost a necessary and sufficient condition. How to effectively control yield shear stress has become a key technical bottleneck for promoting permanent support using high-density, shrinkage-compensating wet-mix shotcrete. The lack of a method for optimizing and adjusting the mix proportions of high-density, shrinkage-compensating wet-mix shotcrete based on yield shear stress is the fundamental reason, and this problem remains to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide a method for controlling the yield shear stress of premixed high-density, shrinkage-compensating wet-mixed shotcrete, thereby solving technical problems in related technologies. To achieve the above objective, this invention provides the following technical solution: a method for controlling the yield shear stress of premixed high-density, shrinkage-compensating wet-mixed shotcrete, comprising the following steps: S1, determining the target value of the yield shear stress in advance. S2. Based on the design strength and slump, the water-cement ratio of high-density, shrinkage-compensating wet-mixed shotcrete is initially selected. Cement quality Silica fume quality Expanding agent quality Water consumption Water-reducing agent quality Total mass of saturated surface-dry aggregate and the mass fraction of aggregates of each particle size Equal mix proportion parameters; S3, collected cement density Silica fume density Density of expanding agent water density Density of water-reducing agent Apparent density of aggregate in saturated surface-dry state aggregate porosity Angle of friction of aggregate (Approximate characterization by measured angle of repose), slurry shear modulus slurry yield shear stress Raw material parameters; S4, calculate the total quantity of aggregates. Aggregate radius slurry volume Aggregate volume Thickness of slurry coating on aggregate surface The yield shear stress is calculated using a given mathematical expression, and the calculated value is obtained. S5. Compare calculated values With target value If the two match, the production mix ratio is determined directly; if they do not match, the unit water consumption is adjusted. Recalculate the mix proportions until the calculated value is reached. With target value S6. Match and determine the production mix ratio; S7. Complete the yield shear stress control and organize concrete production accordingly.

[0005] Preferably, the high-density, shrinkage-compensating wet-sprayed concrete has a water-cement ratio of 0.35 to 0.40, contains 8% to 12% silica fume, and contains 6% to 10% calcium oxide-based expansive agent.

[0006] Preferably, the calculated value of the concrete yield shear stress The expression is:

[0007] ;

[0008] In the formula: - Calculated value of concrete yield shear stress, Pa; -Slurry yield shear stress, Pa; - Pre-exponential factor of aggregate movement equivalent shear modulus, with a value of 27000; -Slurry shear modulus, Pa; - Tangent of the internal friction angle of aggregate, which is numerically equal to the angle of repose; - Aggregate radius, mm; -Thickness of the slurry coating on the aggregate surface, mm; -Water-to-glue ratio; - A constant, with a value of 0.09.

[0009] Preferably, the slurry is a mixture of wet-mixed shotcrete after deducting aggregate; the yield shear stress of the slurry is... Experimental results using the ramp-accelerated shear rate control mode showed that the shear rate increased from 60s to 30s. -1 The slurry shear modulus The actual measurement was conducted using a constant shear rate control mode, with a shear rate of 0.05 s⁻¹. -1 .

[0010] Preferably, the aggregate radius The calculation expression is: ;

[0011] In the formula: -Total mass of aggregate per cubic meter of concrete, kg; -Total quantity of aggregate per cubic meter of concrete, in units; - Apparent density of aggregate in saturated surface-dry state, kg / m³ 3 .

[0012] Preferably, the total amount of aggregate The calculation expression is: In the formula: -Mass fraction of aggregates by size, % - Upper limit of particle size for each aggregate size class, mm; -Lower limit of aggregate size for each size fraction, in mm.

[0013] Preferably, the thickness of the slurry coating on the aggregate surface is... The calculation expression is: ;

[0014] In the formula: - Volume of grout in a single cubic meter of concrete, m 3 ; -Aggregate volume in a single cubic meter of concrete, m³ 3 ; - Aggregate porosity, %.

[0015] Preferably, the volume of grout in the unit volume of concrete is... The calculation expression is: ;

[0016] In the formula: -Water consumption per cubic meter of concrete, kg; - Cement mass in a single cubic meter of concrete, kg; -Weight of silica fume per cubic meter of concrete, kg; - Mass of expansion agent in a single cubic meter of concrete, kg; - Mass of water-reducing agent in a single cubic meter of concrete, kg; -Water density, kg / m³ 3 ; - Cement density, kg / m³ 3 ; -Silica fume density, kg / m³ 3 ; - Density of the expanding agent, kg / m³ 3 ; - Density of water-reducing agent, kg / m³ 3 ; -Air content of concrete, m 3 ;

[0017] Preferably, the aggregate volume The calculation expression is: .

[0018] Preferably, the calculated yield shear stress value With the target value of yield shear stress The two conditions are met if the relative deviation between the calculated value and the target value does not exceed 10% of the target value.

[0019] The beneficial effects of this invention are:

[0020] 1. This invention solves the problem of wet spraying concrete mix proportion production control guided by yield shear stress in the wet spraying construction process, realizes the optimization and adjustment of wet spraying concrete production mix proportion based on target yield shear stress, significantly reduces rebound rate and pipe blockage probability, and has obvious economic and social benefits.

[0021] 2. This invention, through precise control of the yield shear stress of premixed high-density compensating shrinkage wet-mixed shotcrete, can leverage the comprehensive technical advantages of high-density compensating shrinkage wet-mixed shotcrete, such as crack resistance and durability, while synergistically developing the high-efficiency construction performance of the concrete. This plays a key supporting role in promoting the application of high-density compensating shrinkage wet-mixed shotcrete permanent support technology in water conservancy and hydropower projects.

[0022] Of course, any product implementing this invention does not necessarily need to achieve all of the above advantages at the same time. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The flowchart of the method for controlling the yield shear stress of premixed high-density compensated shrinkage wet-sprayed concrete involved in this invention is shown in the present invention.

[0025] Figure 2 This is a schematic diagram of the constant shear rate mode in the slurry shear modulus test in the embodiment.

[0026] Figure 3 This is a schematic diagram of the ramp accelerated shear rate formula for the slurry yield shear stress test in the embodiment. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] like Figure 1-3 As shown, the present invention provides a method for controlling the yield shear stress of premixed high-density compensated shrinkage wet-mixed shotcrete, comprising the following steps: S1, determining the target value of yield shear stress in advance. S2. Based on the design strength and slump, the water-cement ratio of high-density, shrinkage-compensating wet-mixed shotcrete is initially selected. Cement quality Silica fume quality Expanding agent quality Water consumption Water-reducing agent quality Total mass of saturated surface-dry aggregate and the mass fraction of aggregates of each particle size Equal mix proportion parameters; S3, collected cement density Silica fume density Density of expanding agent water density Density of water-reducing agent Apparent density of aggregate in saturated surface-dry state aggregate porosity Angle of friction of aggregate (Approximate characterization by measured angle of repose), slurry shear modulus slurry yield shear stress Raw material parameters; S4, calculate the total quantity of aggregates. Aggregate radius slurry volume Aggregate volume Thickness of slurry coating on aggregate surface The yield shear stress is calculated using a given mathematical expression, and the calculated value is obtained. S5. Compare calculated values With target value If the two match, the production mix ratio is determined directly; if they do not match, the unit water consumption is adjusted. Recalculate the mix proportions until the calculated value is reached. With target value S6. Match and determine the production mix ratio; S7. Complete the yield shear stress control and organize concrete production accordingly.

[0029] In this invention, the high-density, shrinkage-compensating wet-sprayed concrete has a water-cement ratio of 0.35~0.40, contains 8%~12% silica fume, and 6%~10% calcium oxide-based expansive agent. The calculated yield shear stress of the concrete... The expression is:

[0030] ;

[0031] In the formula: - Calculated value of concrete yield shear stress, Pa; -Slurry yield shear stress, Pa; - Pre-exponential factor of aggregate movement equivalent shear modulus, with a value of 27000; -Slurry shear modulus, Pa; - Tangent of the internal friction angle of aggregate, which is numerically equal to the angle of repose; - Aggregate radius, mm; -Thickness of the slurry coating on the aggregate surface, mm; -Water-to-glue ratio; - A constant, with a value equal to 0.09. The slurry is a uniformly mixed mixture obtained by deducting aggregates from the wet-mixed shotcrete proportions; the yield shear stress of the slurry... Experimental results using the ramp-accelerated shear rate control mode showed that the shear rate increased from 60s to 30s. -1 The slurry shear modulus The actual measurement was conducted using a constant shear rate control mode, with a shear rate of 0.05 s⁻¹. -1 .

[0032] The aggregate radius The calculation expression is:

[0033] ;

[0034] In the formula: -Total mass of aggregate per cubic meter of concrete, kg; -Total quantity of aggregate per cubic meter of concrete, in units; - Apparent density of aggregate in saturated surface-dry state, kg / m³ 3 The total quantity of the aggregate. The calculation expression is:

[0035] ;

[0036] In the formula: -Mass fraction of aggregates by size, % - Upper limit of particle size for each aggregate size class, mm; - Lower limit of aggregate size for each grade, mm. Thickness of the slurry coating on the aggregate surface. The calculation expression is:

[0037] ;

[0038] In the formula: - Volume of grout in a single cubic meter of concrete, m 3 ; -Aggregate volume in a single cubic meter of concrete, m³ 3 ; - Aggregate porosity, %. Volume of paste in the unit volume of concrete. The calculation expression is:

[0039] ;

[0040] In the formula: -Water consumption per cubic meter of concrete, kg; - Cement mass in a single cubic meter of concrete, kg; -Weight of silica fume per cubic meter of concrete, kg; - Mass of expansion agent in a single cubic meter of concrete, kg; - Mass of water-reducing agent in a single cubic meter of concrete, kg; -Water density, kg / m³ 3 ; - Cement density, kg / m³ 3 ; -Silica fume density, kg / m³ 3 ; - Density of the expanding agent, kg / m³ 3 ; - Density of water-reducing agent, kg / m³ 3 ; -Air content of concrete, m 3 The aggregate volume The calculation expression is:

[0041] The calculated value of the yield shear stress With the target value of yield shear stress The two conditions are met if the relative deviation between the calculated value and the target value does not exceed 10% of the target value.

[0042] Specifically, the relevant embodiments of the present invention are as follows:

[0043] Example 1:

[0044] 1) Predetermine the target value of yield shear stress. =160 Pa.

[0045] 2) Confirm the design strength grade of wet sprayed concrete as C50 and the slump as 160mm~200mm.

[0046] The preliminary mix design for high-density, shrinkage-compensating wet-mix shotcrete is shown in Table 1, with a water-cement ratio of 0.35, silica fume content of 10%, and expansion agent content of 7%. Cement mass: 439 kg / m³. 3 Silica fume mass 53 kg / m 3 Expansion agent mass 37 kg / m 3 Water consumption: 185 kg / m³ 3 Water-reducing agent mass: 5.29 kg / m³ 3 898 kg / m³ of fine aggregate in saturated surface-dry state 3 735 kg / m³ of coarse aggregate in saturated surface-dry state 3 The proportions of coarse aggregate (5mm-10mm) are 45%, fine aggregate (2.5mm-5mm) is 7.1%, fine aggregate (1.25mm-2.5mm) is 6.6%, fine aggregate (0.63mm-1.25mm) is 11.6%, fine aggregate (0.315mm-0.63mm) is 19.4%, fine aggregate (0.16mm-0.315mm) is 6.8%, fine aggregate (0.08mm-0.16mm) is 0.6%, and fine aggregate (0-0.08mm) is 2.9%.

[0047] Table 1 Preliminary mix design proportions for C50 high-density, shrinkage-compensating wet-mix shotcrete (kg / m³) 3 )

[0048]

[0049] Note: Both coarse and fine aggregates are in a saturated, surface-dry state.

[0050] The cement is P·O42.5 ordinary Portland cement produced by Shangzhi Jinshi Cement Co., Ltd.; the silica fume is 920 semi-densified silica fume provided by Elken International Trading (Shanghai) Co., Ltd.; the expanding agent is calcium oxide expanding agent provided by Tianjin Baoming Co., Ltd.; the parent rock of the aggregates is limestone, with a fineness modulus of 2.9 and a particle size range of 0~5mm for fine aggregates and a particle size range of 5mm~10mm for coarse aggregates; the water-reducing agent is a standard high-performance water-reducing agent provided by Changchun Dongkan New Building Materials Co., Ltd., with a dosage of 1.0% and a water reduction rate of 29.6%.

[0051] 3) Collect cement with a density of 3.08 g / cm³ 3 Silica fume density 2.18 g / cm³ 3 The density of the expanding agent is 2.56 g / cm³. 3 Water density 1.00 g / cm³ 3 Water-reducing agent density: 1.02 g / cm³ 3 The apparent density of the fine aggregate in the saturated surface-dry state is 2.63 g / cm³. 3 The apparent density of the coarse aggregate in its saturated surface-dry state is 2.65 g / cm³. 3 aggregate porosity The internal friction angle of the aggregate is 33.2%. The tangent of the internal friction angle is 36.28° (measured angle of repose 36.28°). The shear modulus of the slurry is 0.734. See the test process Figure 2 As shown, yield shear stress See the test process Figure 3 As shown in Table 1, the mixture prepared according to the concrete mix proportions without adding coarse or fine aggregates and stirred evenly is the slurry to be tested. The slurry shear modulus... The yield shear stress is 56 Pa. The value is 15 Pa.

[0052] 4) Calculate the total quantity of aggregate. Aggregate radius slurry volume Aggregate volume Thickness of slurry coating on aggregate surface The yield shear stress is calculated using a given mathematical expression, and the calculated value is obtained. ;

[0053] =542,744,208;

[0054] =0.6481 mm;

[0055] =0.381 m3 ;

[0056] =0.619 m 3 ;

[0057] According to the formula

[0058] =0.025 mm

[0059] =181 Pa.

[0060] 5) Compare the calculated values With target value If the two match, the production mix ratio is determined directly; if they do not match, the unit water consumption is adjusted. Recalculate the mix proportions until the calculated value is reached. With target value Matching, determining the production mix ratio;

[0061] Calculated yield shear stress The value is 181 Pa, which is close to the target value of the yield shear stress. The relative deviation of 160 Pa is 13%, which is greater than 10%, and the calculated value does not match the target value.

[0062] Increase water consumption to 195 kg / m³ 3 The results of the mix proportion adjustment are shown in Table 2.

[0063] Table 2 Optimized and adjusted mix proportions of C50 high-density shrinkage-compensating wet-mix shotcrete (kg / m³) 3 )

[0064]

[0065] Note: Both coarse and fine aggregates are in a saturated, surface-dry state.

[0066] Water-cement ratio 0.35, silica fume content 10%, expansion agent content 7%. Cement mass 462 kg / m³. 3 Silica fume mass 56 kg / m 3 39 kg / m³ of expanding agent 3 Water consumption: 195 kg / m³ 3 Water-reducing agent mass: 5.57 kg / m³ 3 869 kg / m³ of fine aggregate in saturated surface-dry state 3 711 kg / m³ of coarse aggregate in saturated surface-dry state 3 .

[0067] =525,132,846;

[0068] =0.6481 mm;

[0069] =0.401 m 3 ;

[0070] =0.599 m 3 ;

[0071] According to the formula

[0072] =0.035 mm

[0073] =167 Pa.

[0074] After optimizing and adjusting the mix proportions, the calculated yield shear stress value is... The value is 167 Pa, which is close to the target value of the yield shear stress. The relative deviation of 160 Pa is 4%, which is less than 10%, and the calculated value is consistent with the target value.

[0075] 6) Complete the control of yield shear stress and organize concrete production accordingly.

[0076] Therefore, the concrete mix proportions in Table 2 are determined to be the production mix proportions.

[0077] Example 2:

[0078] 1) Predetermine the target value of yield shear stress. =120 Pa.

[0079] 2) Confirm the design strength grade of wet sprayed concrete as C40 and the slump as 160mm~200mm.

[0080] The preliminary mix design for high-density, shrinkage-compensating wet-mix shotcrete is shown in Table 3, with a water-cement ratio of 0.40, silica fume content of 10%, and expansion agent content of 6%. Cement mass: 410 kg / m³. 3 Silica fume mass 49 kg / m 3 Expansion agent mass 29 kg / m 3 Water consumption: 185 kg / m³ 3 Water-reducing agent mass: 4.63 kg / m³ 3 932 kg / m³ of fine aggregate in saturated surface-dry state 3 763 kg / m³ of coarse aggregate in saturated surface-dry state 3The proportions of coarse aggregate (5mm-10mm) are 45%, fine aggregate (2.5mm-5mm) is 7.1%, fine aggregate (1.25mm-2.5mm) is 6.6%, fine aggregate (0.63mm-1.25mm) is 11.6%, fine aggregate (0.315mm-0.63mm) is 19.4%, fine aggregate (0.16mm-0.315mm) is 6.8%, fine aggregate (0.08mm-0.16mm) is 0.6%, and fine aggregate (0-0.08mm) is 2.9%.

[0081] Table 3 Preliminary mix design proportions for C40 high-density, shrinkage-compensating wet-mix shotcrete (kg / m³) 3 )

[0082]

[0083] Note: Both coarse and fine aggregates are in a saturated, surface-dry state.

[0084] The cement is P·O42.5 ordinary Portland cement produced by Shangzhi Jinshi Cement Co., Ltd.; the silica fume is 920 semi-densified silica fume provided by Elken International Trading (Shanghai) Co., Ltd.; the expanding agent is calcium oxide expanding agent provided by Tianjin Baoming Co., Ltd.; the parent rock of the aggregates is limestone, with a fineness modulus of 2.9 and a particle size range of 0~5mm for fine aggregates and a particle size range of 5mm~10mm for coarse aggregates; the water-reducing agent is a standard high-performance water-reducing agent provided by Changchun Dongkan New Building Materials Co., Ltd., with a dosage of 1.0% and a water reduction rate of 29.6%.

[0085] 3) Collect cement with a density of 3.08 g / cm³ 3 Silica fume density 2.18 g / cm³ 3 The density of the expanding agent is 2.56 g / cm³. 3 Water density 1.00 g / cm³ 3 Water-reducing agent density: 1.02 g / cm³ 3 The apparent density of the fine aggregate in the saturated surface-dry state is 2.63 g / cm³. 3 The apparent density of the coarse aggregate in its saturated surface-dry state is 2.65 g / cm³. 3 aggregate porosity The internal friction angle of the aggregate is 33.2%. The tangent of the internal friction angle is 36.28° (measured angle of repose 36.28°). The shear modulus of the slurry is 0.734. See the test process Figure 2 As shown, yield shear stress See the test process Figure 3 As shown in Table 3, the mixture prepared according to the concrete mix proportions without adding coarse or fine aggregates and stirred evenly is the slurry to be tested. The slurry shear modulus... The yield shear stress is 38 Pa. The value is 10 Pa.

[0086] 4) Calculate the total quantity of aggregate. Aggregate radius slurry volume Aggregate volume Thickness of slurry coating on aggregate surface The yield shear stress is calculated using a given mathematical expression, and the calculated value is obtained. ;

[0087] =563,449,881;

[0088] =0.6481 mm;

[0089] =0.358 m 3 ;

[0090] =0.642 m 3 ;

[0091] According to the formula

[0092] =0.013 mm

[0093] =110 Pa.

[0094] 5) Compare the calculated values With target value If the two match, the production mix ratio is determined directly; if they do not match, the unit water consumption is adjusted. Recalculate the mix proportions until the calculated value is reached. With target value Matching, determining the production mix ratio;

[0095] Calculated yield shear stress The value is 110 Pa, which is close to the target value of the yield shear stress. The relative deviation of 120 Pa is 8%, which is less than 10%, and the calculated value is consistent with the target value.

[0096] 6) Complete the control of yield shear stress and organize concrete production accordingly.

[0097] Therefore, the concrete mix proportions in Table 3 are determined to be the production mix proportions.

[0098] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for controlling the yield shear stress of premixed high-density, shrinkage-compensating wet-mixed shotcrete, characterized in that, Includes the following steps: S1. Predetermine the target value of the yield shear stress. ; S2. Based on the design strength and slump, the water-cement ratio of high-density, shrinkage-compensating wet-mixed shotcrete is initially selected. Cement quality Silica fume quality Expanding agent quality Water consumption Water-reducing agent quality Total mass of saturated surface-dry aggregate and the mass fraction of aggregates of each particle size Mix proportion parameters; S3, Cement Density Silica fume density Density of expanding agent water density Density of water-reducing agent Apparent density of aggregate in saturated surface-dry state aggregate porosity Angle of friction of aggregate (Approximate characterization by measured angle of repose), slurry shear modulus slurry yield shear stress Raw material parameters; S4. Calculate the total quantity of aggregates. Aggregate radius slurry volume Aggregate volume Thickness of slurry coating on aggregate surface The yield shear stress is calculated using a given mathematical expression, and the calculated value is obtained. ; S5. Compare calculated values With target value If the two match, the production mix ratio is determined directly; if they do not match, the unit water consumption is adjusted. Recalculate the mix proportions until the calculated value is reached. With target value Matching, determining the production mix ratio; S6. Complete the control of yield shear stress and organize concrete production accordingly.

2. The method for controlling the yield shear stress of premixed high-density compensated shrinkage wet-mixed shotcrete according to claim 1, characterized in that, The high-density, shrinkage-compensating wet-sprayed concrete has a water-cement ratio of 0.35 to 0.40, contains 8% to 12% silica fume, and 6% to 10% calcium oxide-based expansive agent.

3. The method for controlling the yield shear stress of premixed high-density compensated shrinkage wet-mixed shotcrete according to claim 2, characterized in that, The calculated value of concrete yield shear stress The expression is: ； In the formula: - Calculated value of concrete yield shear stress, Pa; -Slurry yield shear stress, Pa; - Pre-exponential factor of aggregate movement equivalent shear modulus, with a value of 27000; -Slurry shear modulus, Pa; - Tangent of the internal friction angle of aggregate, which is numerically equal to the angle of repose; - Aggregate radius, mm; -Thickness of the slurry coating on the aggregate surface, mm; -Water-to-glue ratio; - A constant, with a value of 0.

09.

4. The method for controlling the yield shear stress of premixed high-density compensated shrinkage wet-mixed shotcrete according to claim 3, characterized in that, The slurry is a uniformly mixed mixture obtained by deducting aggregates from the wet-mixed shotcrete proportions; the yield shear stress of the slurry... Experimental results using the ramp-accelerated shear rate control mode showed that the shear rate increased from 60s to 30s. -1 The slurry shear modulus The actual measurement was conducted using a constant shear rate control mode, with a shear rate of 0.05 s⁻¹. -1 .

5. The method for controlling the yield shear stress of premixed high-density compensated shrinkage wet-mixed shotcrete according to claim 4, characterized in that, The aggregate radius The calculation expression is: ； In the formula: -Total mass of aggregate per cubic meter of concrete, kg; -Total quantity of aggregate per cubic meter of concrete, in units; - Apparent density of aggregate in saturated surface-dry state, kg / m³ 3 .

6. The method for controlling the yield shear stress of premixed high-density compensated shrinkage wet-mixed shotcrete according to claim 5, characterized in that, The total quantity of aggregate The calculation expression is: ； In the formula: -Mass fraction of aggregates by size, % - Upper limit of particle size for each aggregate size class, mm; -Lower limit of aggregate size for each size fraction, in mm.

7. The method for controlling the yield shear stress of premixed high-density compensated shrinkage wet-mixed shotcrete according to claim 6, characterized in that, The thickness of the slurry coating on the surface of the aggregate The calculation expression is: ； In the formula: - Volume of grout in a single cubic meter of concrete, m 3 ; -Aggregate volume in a single cubic meter of concrete, m³ 3 ; - Aggregate porosity, %.

8. The method for controlling the yield shear stress of premixed high-density compensated shrinkage wet-mixed shotcrete according to claim 7, characterized in that, The volume of slurry in the unit volume concrete The calculation expression is: ； In the formula: -Water consumption per cubic meter of concrete, kg; - Cement mass in a single cubic meter of concrete, kg; -Weight of silica fume per cubic meter of concrete, kg; - Mass of expansion agent in a single cubic meter of concrete, kg; - Mass of water-reducing agent in a single cubic meter of concrete, kg; -Water density, kg / m³ 3 ; - Cement density, kg / m³ 3 ; -Silica fume density, kg / m³ 3 ; - Density of the expanding agent, kg / m³ 3 ; - Density of water-reducing agent, kg / m³ 3 ; -Air content of concrete, m 3 .

9. The method for controlling the yield shear stress of premixed high-density compensated shrinkage wet-mixed shotcrete according to claim 8, characterized in that, The aggregate volume The calculation expression is: 。 10. The method for controlling the yield shear stress of premixed high-density compensated shrinkage wet-mixed shotcrete according to claim 9, characterized in that, The calculated value of yield shear stress With the target value of yield shear stress The two conditions are met if the relative deviation between the calculated value and the target value does not exceed 10% of the target value.

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