Magnesium slag-based multi-solid-waste shield wall post-grouting slurry and preparation method thereof

Abstract

The invention discloses magnesium slag-based multi-solid-waste shield wall post-grouting slurry and a preparation method thereof. The magnesium slag-based multi-solid-waste shield wall post-grouting slurry is prepared from the following components in parts by weight: 100 parts of shield muck and 20 parts of a cementing material, and the water-binder ratio is 1.95-2.15; the cementing material is composed of magnesium slag, slag, cement and gypsum. According to the invention, the sandy soil in the shield muck is used as a main raw material, a large amount of magnesium slag and slag and a small amount of cement and gypsum are used as cementing materials to prepare the backfill grouting slurry, and the waste is reused, so that the pollution of the waste to the environment is reduced, and the material cost of the backfill grouting slurry is reduced.

Description

Technical Field

[0001] This invention relates to the field of post-grouting and materials technology for tunnel boring machines (TBMs), and in particular to a magnesium slag-based multi-solid waste TBM wall post-grouting slurry and its preparation method. Background Technology

[0002] With the continuous development of urban subways in my country, a large amount of tunnel boring machine (TBM) slag has been generated. Currently, the slag is dehydrated, compressed into mud cakes, and transported to landfills. However, this method is not only expensive and consumes a large amount of land resources, but also impacts the ecological environment. As the national economy continues to develop, the demand for magnesium is increasing, leading to a rise in magnesium slag. How to handle magnesium slag has become a technical challenge. In tunnel construction, backfill grouting is commonly used to fill the gaps at the tail of the TBM and prevent ground subsidence caused by soil loss. If magnesium slag and slag can be combined and applied to backfill grouting, it can not only reduce the cost of handling slag and magnesium slag, as well as the cost of purchasing raw materials such as sand and clay, but also prevent environmental pollution from slag and magnesium slag. This would achieve green and pollution-free utilization of TBM slag and magnesium slag while reducing project costs. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a magnesium slag-based multi-solid waste shield tunnel wall backfill grout and its preparation method. The grout uses sand from the shield tunnel slag as the main raw material and a large amount of magnesium slag, mineral slag and a small amount of cement and gypsum as cementing materials to prepare the backfill grout. By reusing waste, the pollution of waste to the environment is reduced and the material cost of the backfill grout is lowered.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: a magnesium slag-based multi-solid waste shield tunnel wall backfill grout, which is composed of the following components by weight: 100 parts shield tunnel slag, 20 parts cementing material, and a water-cement ratio of 1.95 to 2.15; the cementing material is composed of magnesium slag, slag, cement and gypsum.

[0005] Preferably, the total weight of the cement and gypsum accounts for 18% to 22% of the weight of the cementitious material.

[0006] Preferably, the weight ratio of cement to gypsum is 3.6 to 4.4.

[0007] Preferably, the weight ratio of magnesium slag to ore slag is 1 to 2.

[0008] Preferably, the water-cement ratio is 1.95, the weight of cement and gypsum accounts for 18% of the total weight of the cementitious materials, the weight ratio of cement to gypsum is 3.6, and the weight ratio of magnesium slag to blast furnace slag is 1.

[0009] Preferably, the water-cement ratio is 2.05, the weight of cement and gypsum accounts for 20% of the total weight of cementitious materials, the weight ratio of cement to gypsum is 4, and the weight ratio of magnesium slag to slag is 1.5.

[0010] Preferably, the water-cement ratio is 2.15, the weight of cement and gypsum accounts for 22% of the total weight of the cementitious materials, the weight ratio of cement to gypsum is 4.4, and the weight ratio of magnesium slag to blast furnace slag is 2.

[0011] Preferably, the tunnel boring machine excavation material is sandy soil with a sand content exceeding 50%.

[0012] Preferably, the cement is 42.5 grade ordinary Portland cement; the magnesium slag has a particle size of 325 mesh; the slag is S95 slag; and the gypsum is desulfurized flue gas gypsum.

[0013] Preferably, the method includes the following steps: measuring the moisture content of the slag, adding water to the slag according to a preset ratio to prepare slurry; adding magnesium slag, blast furnace slag, cement and gypsum to the slurry according to a preset material ratio to obtain slurry raw material; stirring the slurry raw material at a speed of 200 to 600 rpm / min for 5 to 10 minutes to make the slurry raw material evenly mixed to obtain grouting slurry.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. This invention uses sand and soil from shield tunneling slag as the main raw material, and a large amount of magnesium slag, mineral slag and a small amount of cement and gypsum as cementing materials to prepare the back wall grouting slurry. By reusing waste, the pollution of waste to the environment is reduced and the material cost of the back wall grouting slurry is reduced.

[0016] 2. This invention utilizes industrial solid waste such as magnesium slag with high added value to prepare it into grouting slurry for shield tunneling walls. While meeting performance requirements, it significantly reduces the amount of cement used and reduces the carbon emissions of the material system.

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 This invention illustrates the influence of various factors on the fluidity and consistency of the grouting slurry.

[0019] Figure 2 This invention illustrates the influence of various factors on the setting time of the grouting slurry.

[0020] Figure 3 This invention illustrates the influence of various factors on the bleeding rate of the grouting slurry.

[0021] Figure 4This invention relates to the influence of various factors on the volume expansion rate of the grouting slurry.

[0022] Figure 5 This invention relates to the influence of various factors on the unconfined compressive strength of the grouting fluid. Detailed Implementation

[0023] like Figures 1 to 5 As shown, this invention discloses a magnesium slag-based multi-solid waste shield tunnel wall backfill grout, which is composed of the following components by weight: 100 parts shield tunnel slag, 20 parts cementing material, and a water-cement ratio of 1.95 to 2.15; the cementing material is composed of magnesium slag, slag, cement and gypsum.

[0024] The water-cement ratio represents the ratio of water to cementitious materials.

[0025] The total weight of the cement and gypsum accounts for 18% to 22% of the weight of the cementitious materials.

[0026] The weight ratio of cement to gypsum is 3.6 to 4.4.

[0027] The weight ratio of magnesium slag to ore slag is 1 to 2.

[0028] The water-cement ratio is 1.95, the weight of cement and gypsum accounts for 18% of the total weight of cementitious materials, the weight ratio of cement to gypsum is 3.6, and the weight ratio of magnesium slag to blast furnace slag is 1.

[0029] The water-cement ratio is 2.05, the weight of cement and gypsum accounts for 20% of the total weight of cementitious materials, the weight ratio of cement to gypsum is 4, and the weight ratio of magnesium slag to blast furnace slag is 1.5.

[0030] The water-cement ratio is 2.15, the weight of cement and gypsum accounts for 22% of the total weight of cementitious materials, the weight ratio of cement to gypsum is 4.4, and the weight ratio of magnesium slag to blast furnace slag is 2.

[0031] The tunnel boring machine excavation material is sandy soil with a sand content exceeding 50%.

[0032] The cement is 42.5 grade ordinary Portland cement; the magnesium slag has a particle size of 325 mesh; the slag is S95 slag; and the gypsum is desulfurized flue gas gypsum.

[0033] Because the reaction rate of magnesium slag is slow, grinding the magnesium slag finely can activate its activity and increase the reaction rate. Therefore, this application uses a ball mill to grind the magnesium slag to a particle size of 325 mesh. Since the strength requirement of the grouting slurry is greater than 2 MPa, and there are also requirements for the setting time of the grouting slurry, 42.5 grade cement has high strength after hardening and a fast setting time. Therefore, 42.5 grade ordinary Portland cement is used. Adding slag to the magnesium slag can improve the reaction rate and help the slurry to have a certain strength in the early stage to meet the setting time requirements. While providing initial strength, the cement also forms an alkaline environment, which activates the activity of slag and magnesium slag and increases the reaction rate. Furthermore, desulfurized gypsum can be used to replace cement, which can reduce costs and utilize waste.

[0034] A method for preparing a magnesium slag-based multi-solid waste shield tunnel wall post-grouting slurry includes the following steps:

[0035] Measure the moisture content of the slag and add water to the slag according to a preset ratio to prepare mud.

[0036] Magnesium slag, mineral slag, cement and gypsum are added to the mud according to a preset material ratio to prepare slurry raw material;

[0037] Stir the slurry raw materials at a speed of 200-600 rpm / min for 5-10 minutes to ensure uniform mixing and obtain the grouting slurry.

[0038] The performance tests in this application are based on the following: fluidity is determined according to the "Method for Determination of Flowability of Cement Mortar" (GB / T2419-2005); consistency, setting time, and unconfined compressive strength are determined according to the "Standard for Test Methods of Basic Performance of Building Mortar" (JGJ / T70-2009); bleeding rate is determined according to the "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" (GB / T50080-2016); and volume expansion rate is determined by measuring the length, width, and height dimensions of the 28-day sample.

[0039] Example 1

[0040] Preparation work involves grinding the magnesium slag to 325 mesh using a ball mill, using 42.5 grade ordinary Portland cement or desulfurized gypsum, using S95 slag, and using desulfurized flue gas gypsum.

[0041] Prepare raw materials in predetermined weight proportions. In this embodiment, the water-cement ratio is 1.95, the weight of cement and gypsum accounts for 18% of the total weight of cementitious materials, the weight ratio of cement to gypsum is 3.6, and the weight ratio of magnesium slag to slag is 1. Therefore, by weight proportions, there are 100 parts of shield tunneling slag, 0.78 parts of cement, 2.8 parts of gypsum, 8.21 parts of magnesium slag, 8.21 parts of slag, and 39 parts of water.

[0042] A method for preparing a magnesium slag-based multi-solid waste shield tunnel wall post-grouting slurry includes the following steps:

[0043] The moisture content of the slag was measured, and 39 parts by weight of water were added to 100 parts by weight of the shield tunnel slag to prepare mud.

[0044] 0.78 parts by weight of cement, 2.8 parts by weight of gypsum, 8.21 parts by weight of magnesium slag and 8.21 parts by weight of blast furnace slag are added to the mud to prepare the slurry raw material.

[0045] The slurry raw materials are stirred at 400 rpm / min for 8 minutes to ensure uniform mixing and to obtain the grouting slurry.

[0046] The grout prepared in this embodiment was subjected to performance tests on fluidity, consistency, setting time, bleeding rate, and expansion rate. After the grout solidified, compressive strength tests were conducted at 3d, 7d, and 28d. The test results are shown in Table 1.

[0047] Table 1

[0048]

[0049] Flowability reflects the fluidity of the slurry during the curing process; consistency reflects the fluidity of the slurry; setting time reflects the curing speed of the slurry, that is, the time required for the slurry to change from a fluid state to a solid state, and the time required to finally reach complete hardening; bleeding rate reflects the ability of the slurry to release water during the standing process; expansion rate reflects the shrinkage compensation performance of the slurry, used to evaluate the characteristics of the volume change of the slurry during the hardening process; compressive strength reflects the mechanical properties of the slurry under pressure, specifically the material's ability to resist damage or deformation.

[0050] The results in Table 1 indicate that, due to the relatively small amount of water used in this experiment, and the fact that the hydration reaction in the early stage of mud preparation requires water, as well as the later stage of grouting preparation, the grouting slurry produced in this experiment has relatively low fluidity and consistency, and a short setting time.

[0051] Example 2

[0052] Prepare raw materials in predetermined weight proportions. In this embodiment, the water-cement ratio is 2.05, the weight of cement and gypsum accounts for 20% of the total weight of cementitious materials, the weight ratio of cement to gypsum is 4, and the weight ratio of magnesium slag to slag is 1.5. Therefore, by weight proportions, there are 100 parts of shield tunneling slag, 3.2 parts of cement, 0.8 parts of gypsum, 9.6 parts of magnesium slag, 6.4 parts of slag, and 41 parts of water.

[0053] A method for preparing a magnesium slag-based multi-solid waste shield tunnel wall post-grouting slurry includes the following steps:

[0054] The moisture content of the slag was measured, and 41 parts by weight of water were added to 100 parts by weight of the shield tunnel slag to prepare mud.

[0055] 3.2 parts by weight of cement, 0.8 parts by weight of gypsum, 9.6 parts by weight of magnesium slag and 6.4 parts by weight of slag are added to the mud to prepare the slurry raw material;

[0056] The slurry raw materials are stirred at 400 rpm / min for 8 minutes to ensure uniform mixing and to obtain the grouting slurry.

[0057] The grout prepared in this embodiment was subjected to performance tests on fluidity, consistency, setting time, bleeding rate, and expansion rate. After the grout solidified, compressive strength tests were conducted at 3d, 7d, and 28d. The test results are shown in Table 2.

[0058] Table 2

[0059]

[0060] The results in Table 2 show that the grout prepared in this experiment meets the performance requirements of mortar and there is room for optimization. The strength of the grout exceeds the requirements of mortar. Under the premise of ensuring that the strength meets the index, the amount of magnesium slag and slag can be further increased to reduce material costs and improve the utilization rate of waste residue.

[0061] Example 3

[0062] Prepare raw materials in predetermined weight proportions. In this embodiment, the water-cement ratio is 2.15, the weight of cement and gypsum accounts for 22% of the total weight of cementitious materials, the weight ratio of cement to gypsum is 4.4, and the weight ratio of magnesium slag to slag is 2. Therefore, by weight proportions, there are 100 parts of shield tunneling slag, 3.58 parts of cement, 0.82 parts of gypsum, 10.4 parts of magnesium slag, 5.2 parts of slag, and 43 parts of water.

[0063] A method for preparing a magnesium slag-based multi-solid waste shield tunnel wall post-grouting slurry includes the following steps:

[0064] The moisture content of the slag was measured, and 43 parts by weight of water were added to 100 parts by weight of the shield tunnel slag to prepare mud.

[0065] 3.58 parts by weight of cement, 0.82 parts by weight of gypsum, 10.4 parts by weight of magnesium slag and 5.2 parts by weight of slag are added to the mud to prepare the slurry raw material.

[0066] The slurry raw materials are stirred at 400 rpm / min for 8 minutes to ensure uniform mixing and to obtain the grouting slurry.

[0067] The grout prepared in this embodiment was subjected to performance tests on fluidity, consistency, setting time, bleeding rate, and expansion rate. After the grout solidified, compressive strength tests were conducted at 3d, 7d, and 28d. The test results are shown in Table 3.

[0068] Table 3

[0069]

[0070] The results in Table 3 show that the setting time, bleeding rate, and expansion rate of the grout in this experiment all meet the construction requirements. However, the amount of cement and gypsum used in the preparation of the grout is relatively large. After the experiment started, the initial reaction rate of the grout was relatively fast, resulting in low fluidity and consistency of the grout. Moreover, in this experiment, the amount of magnesium slag used was relatively large, which affected the later strength of the grout.

[0071] Based on Examples 1-3, it can be seen that during the preparation of grouting slurry, the weight of each component needs to be strictly controlled and adjusted to ensure that the grouting slurry meets all performance indicators while reducing the amount of cement and gypsum and appropriately increasing the amount of magnesium slag and blast furnace slag. Moreover, the amount of magnesium slag is greater than that of blast furnace slag, so as to achieve the purpose of fully utilizing magnesium slag. The optimal ratio of grouting slurry is selected through orthogonal experiments.

[0072] Example 4

[0073] In accordance with tunnel construction requirements, an orthogonal test of grouting behind the shield tunnel wall was conducted, specifically including the following:

[0074] The study used Box-Behnken in Design-Expert software for orthogonal experimental design. The water-cement ratio, the proportion of cement and gypsum content in the total amount of cementitious materials, the ratio of cement to gypsum, and the ratio of magnesium slag to slag were taken as four influencing factors A, B, C, and D. Four factors, three levels, and five center points were set. The response surface model ratio is shown in Table 4, and the experimental results are shown in Table 5.

[0075] Table 4. Response Surface Model Matching

[0076]

[0077]

[0078] Table 5 Experimental Results

[0079] The samples were prepared according to the proportions of the orthogonal experimental design in Table 4 above. The specific preparation steps are as follows:

[0080] First, measure the moisture content of the slag and soil, and then add an appropriate amount of water to the slag and soil to prepare mud based on the experimental plan;

[0081] Based on the experimental scheme, appropriate amounts of magnesium slag, slag, cement, and gypsum were added to the mud to prepare the slurry raw material.

[0082] The slurry raw materials are stirred at 400 rpm / min for 8 minutes to ensure uniform mixing and to obtain the grouting slurry.

[0083] The mixed grout was subjected to various performance tests and simultaneously poured into molds. After the grout solidified, 3-day, 7-day, and 28-day compressive strength tests were conducted. The influence of each factor on the grout's fluidity and consistency is detailed in [link to relevant documentation]. Figure 1 The results of the variance analysis of fluidity and consistency are shown in Table 6.

[0084] Table 6 Results of Variance Analysis of Flowability and Consistency

[0085]

[0086] Depend on Figure 1 It can be seen that the fluidity and consistency of the grouting slurry are positively correlated with factor A and negatively correlated with factors B, C, and D. According to the variance analysis results of fluidity and consistency in Table 6, the significance of the factors for fluidity is: A>D>B>C; the significance of the factors for consistency is: B>D>A>C.

[0087] according to Figure 1 It can be seen that if A increases, the free water content in the grout will increase, and the fluidity and consistency will increase accordingly. If B increases, the cement will undergo a hydration reaction, and the hemihydrate gypsum will be converted into dihydrate gypsum. In the above process, the water content will decrease due to hydration and evaporation, thus making the grout thicker and reducing its fluidity. If C increases, the cement content will increase and the gypsum content will decrease, the reaction rate of the grout will accelerate, and the water content will decrease due to the hydration reaction, thus reducing the fluidity and consistency of the grout. If the proportion of D increases, the magnesium slag content will increase. After being crushed and ground, the surface area of ​​the magnesium slag particles will increase, generating more dipoles. The dipoles will enhance the adsorption capacity of the particles for water molecules, thereby reducing the fluidity and consistency of the grout.

[0088] The influence of each factor on the slurry setting time is shown in the figure. Figure 2 As shown in Table 7, the results of the analysis of variance for condensation time are presented.

[0089] Table 7 Results of ANOVA on setting time

[0090] source sum of squares Mean Square F value p-value A 2.21 2.21 751.74 <0.0001 B 0.4370 0.4370 148.64 <0.0001 C 0.1045 0.1045 35.55 <0.0001 D 1.76 1.76 599.75 <0.0001

[0091] Depend on Figure 2 It can be seen that the slurry setting time is positively correlated with factors A, C, and D, and negatively correlated with factor B; according to the variance analysis results of setting time, the significance of the factors of setting time is: A>D>B>C.

[0092] according to Figure 2 It can be seen that when A increases, the water content in the grout increases, the spacing between cement particles increases, the hydration products decrease, and the density decreases, thus prolonging the setting time. When B increases, the hydration reaction rate accelerates, further stimulating the activity of magnesium slag and blast furnace slag, thereby shortening the setting time. An appropriate amount of gypsum will react with water, and the resulting hydration products can fill the tiny voids in the grout, thereby compressing the space of free water and accelerating the hydration reaction rate. When C increases, the cement content increases and the gypsum content decreases, weakening the promoting effect of gypsum on the hydration reaction, thus prolonging the setting time. The increased specific surface area of ​​blast furnace slag particles can provide more reaction sites, making the hydration reaction more complete and rapid. When D increases, the blast furnace slag production decreases, the promoting effect of blast furnace slag weakens, and the setting time prolongs.

[0093] The influence of each factor on the slurry bleeding rate is shown in the table below. Figure 3 The results of the analysis of variance on condensation time are shown in Table 8.

[0094] Table 8. Results of Analysis of Variance for Bleeding Rate

[0095] source sum of squares Mean Square F value p-value A 0.5941 0.5941 501.43 <0.0001 B 0.0721 0.0721 60.84 <0.0001 C 0.4370 0.4370 368.86 <0.0001 D 0.1850 0.1850 156.16 <0.0001

[0096] Depend on Figure 3 It can be seen that the bleeding rate of the grout is positively correlated with factors A, C, and D, and negatively correlated with factor B. According to Table 8, the significance of the factors in the bleeding rate is: A>C>D>B.

[0097] according to Figure 3 It can be seen that when A increases, the free water in the grout increases, and the bleeding rate rises; when B increases, the hydration reaction rate accelerates, further stimulating the activity of slag and magnesium slag, increasing the hydration reaction rate, and thus reducing the bleeding rate of the grout; gypsum has water absorption properties and can absorb some of the free water in the mortar, converting it into more stable bound water, thereby reducing the bleeding phenomenon; when C increases, the gypsum content decreases, the free water absorbed by gypsum decreases, and the bleeding rate of the grout increases; slag is rich in active substances, which can react chemically with cement hydration products to generate CSH gel energy products. These products can quickly fill the pores of the grout, improve the microstructure of the grout, and thus reduce the bleeding rate; when D increases, the slag content decreases, the number of reactions between slag and cement hydration products decreases, and the bleeding rate of the grout increases.

[0098] The influence of each factor on the volume expansion rate of the slurry is shown in the table below. Figure 4 The results of the variance analysis of the volume expansion rate are shown in Table 9.

[0099] Table 9 Results of the analysis of variance for volume expansion rate

[0100] source sum of squares Mean Square F value p-value A 4.20 4.20 383.79 <0.0001 B 1.86 1.86 169.61 <0.0001 C 0.6769 0.6769 61.84 <0.0001 D 6.12 6.12 559.17 <0.0001

[0101] Depend on Figure 4 It can be seen that the volume expansion rate of the grout is positively correlated with factor A and negatively correlated with factors B, C and D. According to Table 9, the significance of the volume expansion rate factors is: D>A>B>C.

[0102] according to Figure 4 It can be seen that when A increases, the water content in the grout increases, and the grout can maintain a certain humidity during the hardening process, reducing the drying shrinkage caused by water evaporation. When B increases, the amount of magnesium slag and slag decreases, the volume micro-expansion caused by the hydration reaction of magnesium slag and slag decreases, and the overall volume expansion rate of the grout decreases. Compared with pure cement, the combination of cement and gypsum has a stronger promoting effect on the hydration reaction of magnesium slag and slag, which can make the hydration reaction of magnesium slag and slag more complete and produce more hydration products, thereby effectively offsetting the self-shrinkage of the grout. However, when C increases, the amount of gypsum decreases, the promoting effect of cement and gypsum decreases, thereby reducing the volume expansion rate. When D increases, the amount of magnesium slag increases, the amount of slag decreases, the synergistic effect of magnesium slag and slag weakens, the corresponding hydration products decrease, the volume micro-expansion is reduced, and the volume expansion rate is reduced.

[0103] The influence of each factor on the strength of the grout at 3d, 7d, and 28d is shown in the table below. Figure 5 The results of the variance analysis of the unconfined compressive strength are shown in Table 10.

[0104] Table 10 Results of Unconfined Compressive Strength Analysis

[0105]

[0106] Depend on Figure 5 It can be seen that the compressive strength of the grout at 3d, 7d, and 28d is negatively correlated with factors A, C, and D, and positively correlated with factor B. According to the analysis of variance, the significance of the factors for 3d strength is: A>D>C>B; for 7d strength, it is: D>A>C>B; and for 28d strength, it is: D>A>B>C.

[0107] according to Figure 5It can be seen that as A increases, the free water content in the grout increases, the curing effect of the cementitious material weakens, and thus the compressive strength of the grout decreases. With the increase of B, the cement hydration reaction rate accelerates, and the resulting alkaline environment, along with sulfate ions in the gypsum, jointly stimulates the activity of the slag and magnesium slag, increasing their reaction rate and enhancing the compressive strength of the grout. Cement hydration generates Ca(OH)2, raising the pH value of the grout. In an alkaline environment, the calcium aluminate generated by gypsum and cement hydration reacts to form hydraulically hydrated calcium sulfoaluminate, a process that further enhances the grout's compressive strength. The rapid consumption of Ca(OH)2 promotes the utilization of Al2O3 in the slag, improving the microstructure of the grouting slurry. Calcium sulfoaluminate hydrate, as a hydraulic product, accelerates the hardening process and increases the strength of the slurry; therefore, gypsum plays a role in improving strength. However, with increasing carbon content, the gypsum content decreases, weakening its effect and reducing the compressive strength of the grouting slurry. As the alkalinity of the grouting slurry increases and sulfate ions are generated during gypsum hydration, the structure of the magnesium slag and the slag is disrupted. MgO in the magnesium slag undergoes a hydration reaction, promoting the hydration of the slag, and the generated OH... - This increased the pH value of the grouting slurry; under alkaline conditions, the colloids on the slag surface decomposed, releasing active ions, which reacted with Ca... 2+ The isocation reaction generates CSH gel and hydrated magnesia, etc.; these newly generated gel substances not only enhance the cohesion and strength of the grout, but also improve its microstructure; therefore, as D increases, the content of magnesium slag increases and the content of slag decreases, the synergistic effect of the two weakens, and the compressive strength of the grout decreases.

[0108] According to the orthogonal experimental results, the fluidity and consistency increase with increasing water-cement ratio, and decrease with increasing cement and gypsum content, cement and gypsum ratio, and magnesium slag and slag ratio in the cementitious material; the setting time increases with increasing water-cement ratio, cement and gypsum ratio, and magnesium slag and slag ratio, and decreases with increasing cement and gypsum content in the cementitious material; the bleeding rate increases with increasing water-cement ratio, cement and gypsum ratio, and magnesium slag and slag ratio, and decreases with increasing cement and gypsum content in the cementitious material; the volume expansion rate increases with increasing water-cement ratio, and decreases with increasing cement and gypsum content in the cementitious material. The compressive strength decreases with increasing water-cement ratio, cement-gypsum ratio, and magnesium slag-slag ratio; it increases with increasing cement and gypsum content in the cementitious material. Therefore, to reduce the raw material cost of grouting slurry preparation, it is necessary to adjust the water-cement ratio, cement and gypsum content, cement-gypsum ratio, and magnesium slag-slag ratio in the grouting slurry raw materials, so that the cement content is relatively reduced to lower costs, and the magnesium slag content is relatively increased to achieve the purpose of waste recycling. By adjusting the corresponding proportions, the performance of the grouting slurry can meet the requirements.

[0109] The performance indicators of backfill grouts from both domestic and international sources are shown in Table 11:

[0110] Table 11 Performance Indicators of Grouting Fluid Behind Wall

[0111]

[0112] Using response surface methodology, based on the influence of the above factors on the performance of the grouting slurry, combined with performance indicators and considering economic factors, the optimal mix ratio was obtained. The optimal mix ratio is: A = 2.05, B = 18, C = 4.235, D = 2. According to the mass percentage of cementitious material and shield tunneling slag being 20%, the grouting slurry behind the shield wall of the magnesium slag-based solid waste shield contains 100 parts shield tunneling slag, 2.9 parts cement, 0.7 parts gypsum, 10.9 parts magnesium slag, 5.5 parts slag, and 41 parts water.

[0113] Example 5

[0114] The grouting fluid behind the shield wall in this embodiment consists of the following components by weight: 100 parts shield slag, 2.9 parts cement, 0.7 parts gypsum, 10.9 parts magnesium slag, 5.5 parts slag, and 41 parts water.

[0115] The specific production steps are as follows:

[0116] First, measure the moisture content of the slag and soil. Based on the above optimal ratio, add 41 parts by weight of water to 100 parts by weight of the slag and soil to prepare slurry.

[0117] Based on the optimal ratio, 10.9 parts by weight of magnesium slag, 5.5 parts by weight of slag, 2.9 parts by weight of cement and 0.7 parts by weight of gypsum were added to the mud to prepare the slurry raw material.

[0118] The slurry raw materials are stirred at 400 rpm / min for 8 minutes to ensure uniform mixing and to obtain the grouting slurry.

[0119] Comparative Example 1

[0120] The grouting slurry prepared from pure cement consists of the following components by weight: 100 parts shield tunneling excavation soil, 20 parts cement, and 41 parts water.

[0121] Table 12 shows a comparison of the performance indicators of the grouting slurry made of pure cement with those of the grouting slurry of this application:

[0122] Table 12 Comparison of performance indicators between grouting slurry made from pure cement and grouting slurry of this application.

[0123]

[0124]

[0125] As shown in Table 12, the fluidity and consistency of the grout in this application are lower than those of pure cement grout, the bleeding rate is higher than that of pure cement grout, the setting time meets the requirements of the construction site, the volume expansion is controlled within 2%, and the 28-day strength is about 80% of that of pure cement group. The grout in this application meets all the performance indicators of the wall-mounted grout while the material cost is lower than that of pure cement group, and it has strong ecological and environmental value.

[0126] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A magnesium slag-based multi-solid waste shield tunnel wall post-grouting slurry, characterized in that, The material is composed of the following components by weight: 100 parts of shield tunneling slag, 20 parts of cementitious material, and a water-cement ratio of 1.95 to 2.15; the cementitious material is composed of magnesium slag, slag, cement and gypsum.

2. The magnesium slag-based multi-solid waste shield tunnel wall backfill grouting fluid according to claim 1, characterized in that, The total weight of the cement and gypsum accounts for 18% to 22% of the weight of the cementitious materials.

3. The magnesium slag-based multi-solid waste shield tunnel wall backfill grouting fluid according to claim 2, characterized in that, The weight ratio of cement to gypsum is 3.6 to 4.

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4. The magnesium slag-based multi-solid waste shield tunnel wall backfill grouting fluid according to claim 3, characterized in that, The weight ratio of magnesium slag to ore slag is 1 to 2.

5. A magnesium slag-based multi-solid waste shield tunnel wall backfill grouting fluid according to claim 4, characterized in that, The water-cement ratio is 1.95, the weight of cement and gypsum accounts for 18% of the total weight of cementitious materials, the weight ratio of cement to gypsum is 3.6, and the weight ratio of magnesium slag to blast furnace slag is 1.

6. A magnesium slag-based multi-solid waste shield tunnel wall backfill grouting fluid according to claim 4, characterized in that, The water-cement ratio is 2.05, the weight of cement and gypsum accounts for 20% of the total weight of cementitious materials, the weight ratio of cement to gypsum is 4, and the weight ratio of magnesium slag to blast furnace slag is 1.

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7. A magnesium slag-based multi-solid waste shield tunnel wall backfill grouting fluid according to claim 4, characterized in that, The water-cement ratio is 2.15, the weight of cement and gypsum accounts for 22% of the total weight of cementitious materials, the weight ratio of cement to gypsum is 4.4, and the weight ratio of magnesium slag to blast furnace slag is 2.

8. A magnesium slag-based multi-solid waste shield tunnel wall backfill grouting fluid according to claim 1, characterized in that, The tunnel boring machine excavation material is sandy soil with a sand content exceeding 50%.

9. A magnesium slag-based multi-solid waste shield tunnel wall backfill grouting fluid according to claim 1, characterized in that, The cement is 42.5 grade ordinary Portland cement; the magnesium slag has a particle size of 325 mesh; the slag is S95 slag; and the gypsum is desulfurized flue gas gypsum.

10. A method for preparing a magnesium slag-based multi-solid waste shield tunnel wall backfill grout according to claim 1, characterized in that, Includes the following steps: Measure the moisture content of the slag and add water to the slag according to a preset ratio to prepare mud. Magnesium slag, mineral slag, cement and gypsum are added to the mud according to a preset material ratio to prepare slurry raw material; Stir the slurry raw materials at a speed of 200-600 rpm / min for 5-10 minutes to ensure uniform mixing and obtain the grouting slurry.

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