Adjustable backfill material based on low-viscosity fine-grained soil and preparation method of adjustable backfill material

Abstract

The invention belongs to the technical field of resource utilization of engineering residue soil, and particularly discloses an adjustable backfill material based on low-viscosity fine-grained soil and a preparation method of the adjustable backfill material. The adjustable backfill material comprises the following components in percentage by mass: 65-85% of low-viscosity engineering waste soil, 5-10% of a high-strength curing material system, 0-1% of a fluidity promoting material system, 0-1.5% of a compactness reinforcing material system and 5-25% of water, wherein the sum of the percentages of the components is 100%. According to the backfill material, low-viscosity fine-grained soil serves as base soil, three different material systems including a high-strength curing material system, a fluidity promoting material system and a compactness enhancing material system are doped, and cured soil with the properties of high fluidization, self-compaction, controllable strength, low permeability and the like is obtained; the raw materials of the backfill material are simple and easy to obtain, the process is simple and convenient, different engineering requirements can be met by regulating and controlling the proportion of different material systems, and the problems that the muck containing area is insufficient and the disposal cost is high can be effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of resource utilization of engineering slag, and in particular to an adjustable backfill material based on low-viscosity fine-grained soil and a preparation method thereof. Background Art

[0002] At present, in the field of underground engineering in my country, backfilling problems of foundation pits, underground cavities (mining pits and mine caves, karst caves), underground pipelines, underground pipe corridors, etc. are often encountered, and the problem of engineering slag is becoming increasingly prominent. The disposal of slag faces problems such as insufficient accommodation area and high disposal costs. There is an urgent need for resource utilization of engineering slag. In response to these construction needs, practitioners currently use some specific curing agents to solidify and treat engineering slag before backfilling to achieve the purpose of turning waste into treasure. In the preparation method of the curing agent, different proportions of cementitious materials (such as cement), active mixed materials (such as fly ash, steel slag), micro-expansive materials (such as quicklime, gypsum), activators (sodium hydroxide, sodium carbonate), dispersants (polycarboxylic acid water reducers), early strength agents, retarders, shrinkage reducers, viscosity regulators, water retention agents and penetrants are generally used.

[0003] The existing method of solidifying and backfilling construction waste has some defects, such as:

[0004] Patent application CN112142406A discloses a soil curing agent for high fluidity solidified soil, the raw materials of which are composed of gelling material, active mixed material, micro-expansion material, activator, dispersant, hydrophobic nano-silicon oxide, inorganic polyphosphate, polyquaternary ammonium salt and its derivatives, the amount of the soil curing agent is 3-15% of the mass of the base soil, and the solidified soil mixture prepared by the soil curing agent has the advantages of high fluidity and dispersion retention, low construction cost, strong adaptability to the base soil, high mechanical properties, etc. However, the curing agent requires many types of materials, and a conical twin-screw spiral mixer is also required during preparation, the process is relatively complicated, and it is not suitable for promotion.

[0005] Patent CN114940611B discloses a fluidized solidified soil based on gold tailings and a preparation method thereof. The fluidized solidified soil prepared by adding gold tailings (particles are mainly clay particles) as the main material and adding dispersants and solidifying materials can be used as filling materials and solve the pollution problem caused by gold tailings landfill. The gold tailings materials required for the solidified soil are difficult to obtain and difficult to apply to other types of base soils, and have no promotion value.

[0006] In addition, different engineering scenarios have different performance requirements for backfill soil, and usually have different emphases on properties such as fluidity, density, and strength. The existing engineering waste solidification backfill materials do not have good performance controllability and are difficult to meet diverse engineering needs, so their applicable scenarios are limited. Summary of the invention

[0007] To solve the above problems, the present invention provides an adjustable backfill material based on low-viscosity fine-grained soil and a preparation method thereof. The present invention uses low-viscosity fine-grained soil such as silt and sand as the base soil, and mixes three different material systems, namely, a high-strength solidification material system, a fluidity-promoting material system, and a density-enhancing material system, to obtain a solidified soil having high fluidization, self-compactness, controllable strength, low permeability, and the like, and is green and environmentally friendly, efficient in construction, controllable in quality, and low in cost. The present invention can meet different engineering needs by adjusting the ratio of different material systems, is suitable for different engineering scenes, and more efficiently optimizes the role of each solidification material system. For example, in a certain project, the strength of the soil used is very high, and the permeability and density requirements are relatively low. The material dosage of the strength solidification system can be increased, and the materials contained in the density-enhancing system can be added or added less. In this way, without wasting materials, the engineering needs are also met, and the problem of the difficulty of absorbing engineering slag is effectively solved, and the required raw materials are simple and easy to obtain, with good economy; the carbon emissions can be effectively controlled during the preparation process, and the environmental protection value is relatively high.

[0008] In order to achieve the above object, the specific technical solution adopted by the present invention is as follows:

[0009] In a first aspect, the present invention provides an adjustable backfill material based on low-viscosity fine-grained soil, which comprises the following components in percentage by mass: 65-85% low-viscosity engineering waste soil, 5-10% high-strength solidifying material system, 0-1% fluidity-promoting material system, 0-1.5% density-enhancing material system, and 5-25% water, and the sum of the percentages of each component is 100%; the high-strength solidifying material system comprises cement and / or fly ash, the fluidity-promoting material system comprises a water reducer, and the density-enhancing material system comprises an activator and / or a fiber material.

[0010] The addition of three different material systems of the present invention plays a key role in the treatment of low-viscosity fine-grained soil. The high-strength solidification material system improves the early strength and stability of the solidified soil through hydration reaction, and provides an alkaline environment at the same time. Under an alkaline environment, the density enhancement material system undergoes a series of physical and chemical reactions with the soil body, and solidifies with the soil body to generate hydration products to fill the internal voids of the soil particles, thereby increasing the overall density and stability, and continuously improving the strength of the solidified soil. The addition of the fluidity-promoting material system is to maintain the fluidity of the solidified soil, and can also form a synergistic effect with the high-strength solidification material system to improve the early strength of the treated soil. In the density enhancement material system, the stimulator and the fiber material should be used in combination, and the combined use has a higher compressive strength. If the tensile properties of the solidified soil are not required to be high, the fiber material can be reduced or not used. In the high-strength solidification system, fly ash is added on the basis of cement, and the compressive strength of the backfill material at each age (7d, 28d, 60d) is improved.

[0011] Preferably, the mass percentage of the fluidity-promoting material system is 0.1-0.8%, and the mass percentage of the density-enhancing material system is 0.3-1.2%. The backfill material has good comprehensive performance within this formula range. The ratio of different material systems can be adjusted within this range to meet different engineering needs, with better results.

[0012] Preferably, the cement is selected from one or more of aluminate cement, silicate cement and sulphoaluminate cement.

[0013] Preferably, the water reducer is a polycarboxylate water reducer or a melamine water reducer, and the polycarboxylate water reducer is an early strength polycarboxylate water reducer, a slow-release polycarboxylate water reducer or an anti-mud polycarboxylate water reducer.

[0014] Preferably, the activator is selected from one or more of sodium hydroxide, sodium sulfate, sodium silicate, sodium carbonate, aluminum sulfate slag, desulfurization ash and wood calcium.

[0015] The fiber material is one or more of steel fiber, plant fiber, glass fiber and synthetic fiber.

[0016] Preferably, the low-viscosity engineering waste soil is low-viscosity, non-viscosity fine-grained soil or mixed soil, the content of particles with a particle size less than 0.005 mm is less than 20% of the total weight, the content of particles with a particle size greater than 0.075 mm is greater than 40% of the total weight, the proportion of soil particles with a particle size less than 2 cm is greater than 95%, and the maximum particle size of the particles is not greater than 10 cm. The particle size control range basically covers low (non-) viscosity soils such as sandy and powdery soils, which are common types of slag and are easy to obtain. The corresponding three systems and proportions have good applicability to engineering slag within this particle size range. If it exceeds this range, the effect is poor. For example, the content of particles with a particle size less than 0.005 mm exceeds 20%. Under the same conditions and the same proportion, the strength and fluidity of the backfill material will be significantly reduced. Therefore, in addition to the raw material ratio, the soil properties are also crucial in the present invention.

[0017] In a second aspect, the present invention provides a method for preparing the above-mentioned adjustable backfill material based on low-viscosity fine-grained soil, comprising the following steps:

[0018] (1) weighing a high-strength curing material system and a fluidity-promoting material system according to a mass ratio, stirring them in a stirring container, and simultaneously introducing air during the stirring process to uniformly mix the materials into a multi-type mixed material system;

[0019] (2) Weighing construction waste soil and water in a mass ratio, stirring them in a stirring container to fully mix them into a waste soil suspension;

[0020] (3) The waste soil suspension and various mixed material systems are mixed and stirred, and finally the density enhancing material system is added and mixed evenly to obtain an adjustable backfill material.

[0021] Preferably, in step (1), the stirring speed is 70-100 rpm and the stirring time is 6-9 minutes.

[0022] Preferably, in step (2), the stirring speed is 80-115 rpm and the stirring time is 5-8 minutes.

[0023] The present invention has the following beneficial effects:

[0024] 1. The addition of high-strength solidifying material system ensures that the strength of the treated low-viscosity fine-grained soil is rapidly improved. Through a series of chemical reactions such as hydration reactions, chemical products such as gel are generated, which directly act on the low-viscosity fine-grained soil to improve its strength characteristics.

[0025] 2. The fluidity-promoting material system improves the uniformity of the treated soil, absorbs excess pore water, and enables it to quickly have good fluidity and maintain fluidity.

[0026] 3. The density enhancement material system increases the density of the solidified soil structure, improves the early strength of the solidified fluidized soil, ensures the stable growth of subsequent strength, and improves the structural characteristics of low-viscosity fine-grained soil.

[0027] 4. The processing of the backfill material of the present invention has the characteristic of being controllable, and the proportion and amount of the corresponding processing material can be adjusted according to the actual project requirements, thereby achieving an efficient and rapid processing effect, and the processing method is highly targeted.

[0028] 5. By entraining air during the mixing and solidifying soil, the problem of uneven mixing of low-viscosity fine-grained soils such as silt and sand is solved. The preparation method of the backfill material of the present invention can ensure the uniformity and easy mixing of the solidified soil.

[0029] 6. The present invention can effectively solve the problems of insufficient slag storage area and high disposal cost. The prepared adjustable backfill material based on low-viscosity fine-grained soil is suitable for multiple scenarios such as backfilling of foundation pit fertilizer troughs. The raw materials are simple and easy to obtain, the process is simple, and it is easy to promote and apply. DETAILED DESCRIPTION

[0030] The present invention is further described below with reference to specific examples.

[0031] Example 1

[0032] A backfill material, the proportion of each component is: 75 parts of engineering waste soil, 6 parts of high-strength solidification material system, 0.2 parts of fluidity-promoting material system, 0.3 parts of density-enhancing material system and 18.5 parts of water. Among them, the engineering waste soil is non-cohesive fine-grained soil, and the particle gradation is: 6.8% (<0.005mm), 47.3% (0.005-0.075mm), 45.9% (0.075-0.25mm); the high-strength solidification material system is cement; the fluidity-promoting material system is polycarboxylic acid; the density-enhancing material system is sodium hydroxide.

[0033] The preparation method of the backfill material is as follows:

[0034] (1) weighing a high-strength curing material system and a fluidity-promoting material system according to a mass ratio, stirring them in a stirring container at a speed of 70-100 rpm for 6-9 minutes, and simultaneously introducing air during the stirring process to uniformly mix the mixed material system into a multi-type mixed material system;

[0035] (2) Weighing construction waste soil and water according to mass ratio, stirring in a stirring container at a speed of 80-115 rpm for 5-8 minutes to fully mix and uniformly form a waste soil suspension;

[0036] (3) The waste soil suspension and various mixed material systems are mixed and stirred for 2-3 minutes, and finally the density enhancing material system is added and mixed evenly to obtain an adjustable backfill material.

[0037] The backfill material was tested for fluidity (expansion) and unconfined compressive strength, and the performance test results were: expansion 265mm, 7d strength 1.55MPa, 28d strength 3.42MPa, and 60d strength 3.86MPa.

[0038] Example 2

[0039] A backfill material, the proportion of each component is: 65 parts of engineering waste soil, 10 parts of high-strength solidification material system, 0.4 parts of fluidity-promoting material system, 0.6 parts of density-enhancing material system and 24 parts of water. Among them, the engineering waste soil is non-cohesive fine-grained soil, and the particle gradation is: 6.8% (<0.005mm), 47.3% (0.005-0.075mm), 45.9% (0.075-0.25mm); the high-strength solidification material system is composed of cement and fly ash, and the mass ratio of cement to fly ash is 4:1; the fluidity-promoting material system is polycarboxylic acid; and the density-enhancing material system is desulfurized ash.

[0040] The preparation method of the backfill material is as follows:

[0041] (1) Weighing a high-strength solidifying material system and a fluidity-promoting material system according to a mass ratio, crushing fly ash into about 50 μm, sieving and evenly mixing with other raw materials, stirring in a stirring container at a speed of 70-100 rpm for 6-9 minutes, and simultaneously introducing air during the stirring process to uniformly mix into a multi-type mixed material system;

[0042] (2) Weighing construction waste soil and water according to mass ratio, stirring in a stirring container at a speed of 80-115 rpm for 5-8 minutes to fully mix and uniformly form a waste soil suspension;

[0043] (3) The waste soil suspension and various mixed material systems are mixed and stirred for 2-3 minutes, and finally the density enhancing material system is added and mixed evenly to obtain an adjustable backfill material.

[0044] The test results of backfill material performance are: expansion 280mm, 7d strength 1.79MPa, 28d strength 4.05MPa, 60d strength 4.13MPa.

[0045] Example 3

[0046] A backfill material, wherein the proportions of each component are: 79 parts of engineering waste soil, 6 parts of high-strength solidification material system, 0.1 parts of fluidity-promoting material system, 0.6 parts of density-enhancing material system and 14.3 parts of water. Among them, the engineering waste soil is non-cohesive fine-grained soil, and the particle gradation is: 6.8% (<0.005mm), 47.3% (0.005-0.075mm), 45.9% (0.075-0.25mm); the high-strength solidification material system is composed of cement and fly ash, and the mass ratio of cement to fly ash is 4:1; the fluidity-promoting material system is melamine; the density-enhancing material system is desulfurization ash + synthetic fiber, and the proportion of synthetic fiber does not exceed 1% of the total mass of the two. The preparation method of the backfill material is the same as that of Example 2.

[0047] The test results of backfill material performance are: expansion 225mm, 7d strength 1.83MPa, 28d strength 4.12MPa, 60d strength 4.28MPa.

[0048] Example 4

[0049] A backfill material, wherein the proportions of each component are: 83 parts of construction waste soil, 7 parts of high-strength solidifying material system, 0.8 parts of fluidity-promoting material system, 1.2 parts of density-enhancing material system and 8 parts of water. The construction waste soil is a non-viscous mixed soil, and the particle gradation is: 3.9% (<0.005mm), 43.7% (0.005-0.075mm), 52.4% (0.075-0.25mm); the high-strength solidifying material system is composed of cement and fly ash, and the mass ratio of cement to fly ash is 4:1; the fluidity-promoting material system is polycarboxylic acid; and the density-enhancing material system is sodium silicate. The preparation method of the backfill material is the same as that of Example 2.

[0050] The performance test results of the backfill material are: expansion 243mm, 7d strength 1.96MPa, 28d strength 4.15MPa, and 60d strength 4.37MPa.

[0051] Comparative Example 1

[0052] A backfill material, wherein the proportions of each component are: 75 parts of engineering waste soil, 6 parts of high-strength solidifying material system and 19 parts of water. The engineering waste soil is non-cohesive fine-grained soil, and the particle gradation is: 6.8% (<0.005mm), 47.3% (0.005-0.075mm), 45.9% (0.075-0.25mm); the high-strength solidifying material system is cement.

[0053] The preparation method of the backfill material is as follows:

[0054] (1) Weighing construction waste soil and water according to mass ratio, stirring in a stirring container at a speed of 80-115 rpm for 5-8 minutes to fully mix and uniformly form a waste soil suspension;

[0055] (2) Weigh the high-strength solidifying material system according to the mass ratio, mix the waste soil suspension and the high-strength solidifying material system and stir for 2-3 minutes to obtain the backfill material.

[0056] The test results of backfill material performance are: expansion 174mm, 7d strength 1.13MPa, 28d strength 2.82MPa, 60d strength 3.14MPa. The specimens showed obvious shrinkage during the curing process, and cracks were found in some parts.

[0057] Comparative Example 2

[0058] A backfill material, the proportion of each component is: 79 parts of engineering waste soil, 6 parts of high-strength solidification material system, 0.1 parts of fluidity-promoting material system and 14.9 parts of water. Among them, the engineering waste soil is non-cohesive fine-grained soil, and the particle gradation is: 6.8% (<0.005mm), 47.3% (0.005-0.075mm), 45.9% (0.075-0.25mm); the high-strength solidification material system is composed of cement and fly ash, and the mass ratio of cement to fly ash is 4:1; the fluidity-promoting material system is melamine.

[0059] The preparation method of the backfill material is as follows:

[0060] (1) weighing a high-strength curing material system and a fluidity-promoting material system according to a mass ratio, stirring them in a stirring container, and simultaneously introducing air during the stirring process to uniformly mix the materials into a multi-type mixed material system;

[0061] (2) Weighing construction waste soil and water in a mass ratio, stirring them in a stirring container to fully mix them into a waste soil suspension;

[0062] (3) The waste soil suspension and the various mixed material systems are mixed and stirred for 2-3 minutes to obtain an adjustable backfill material.

[0063] The test results of the backfill material performance are: expansion 223mm, 7d strength 1.36MPa, 28d strength 3.42MPa, 60d strength 3.60MPa. After the sample is destroyed, the degree of crushing is significantly greater than that of the example sample.

[0064] Comparative Example 3

[0065] A backfill material, the proportion of each component is: 83 parts of engineering waste soil, 7 parts of high-strength solidifying material system, 1.2 parts of density enhancing material system and 8.8 parts of water. Among them, the engineering waste soil is non-cohesive mixed soil, and the particle gradation is: 3.9% (<0.005mm), 43.7% (0.005-0.075mm), 52.4% (0.075-0.25mm); the high-strength solidifying material system is composed of cement and fly ash, and the mass ratio of cement to fly ash is 4:1; the density enhancing material system is sodium silicate.

[0066] The preparation method of the backfill material is as follows:

[0067] (1) Weighing construction waste soil and water according to mass ratio, stirring in a stirring container at a speed of 80-115 rpm for 5-8 minutes to fully mix and uniformly form a waste soil suspension;

[0068] (2) Weigh the high-strength solidifying material system and the density enhancing material system according to the mass ratio, mix the waste soil suspension and the various mixed material systems for 3-5 minutes, and finally add the density enhancing material system and mix evenly to obtain the adjustable backfill material.

[0069] The test results of backfill material performance are: expansion 150mm, 7d strength 1.48MPa, 28d strength 3.69MPa, 60d strength 3.93MPa.

[0070] Comparative Example 4

[0071] A backfill material, wherein the proportions of each component are: 75 parts of engineering waste soil, 0.4 parts of a fluidity-promoting material system, 0.6 parts of a density-enhancing material system and 24 parts of water. The engineering waste soil is non-cohesive fine-grained soil, and the particle gradation is: 6.8% (<0.005mm), 47.3% (0.005-0.075mm), 45.9% (0.075-0.25mm); the fluidity-promoting material system is polycarboxylic acid; and the density-enhancing material system is desulfurized ash.

[0072] The preparation method of the backfill material is as follows:

[0073] (1) Weighing construction waste soil and water according to mass ratio, stirring in a stirring container at a speed of 80-115 rpm for 5-8 minutes to fully mix and uniformly form a waste soil suspension;

[0074] (2) Weigh the fluidity-promoting material system and the density-enhancing material system according to the mass ratio, mix the waste soil suspension with the fluidity-promoting material system and the density-enhancing material system and stir for 2-3 minutes to obtain the backfill material.

[0075] Backfill material test results: expansion 290mm, slurry failed to solidify, no strength at 7d, 28d, and 60d.

[0076] Comparative Example 5

[0077] A backfill material is basically the same as Example 2, except that the engineering waste soil in this comparative example is clay soil, and the particle grading is: 11.5% (<0.005mm), 81.3% (0.005-0.075mm), and 7.2% (0.075-0.25mm).

[0078] The preparation method of the backfill material is basically the same as that of Example 1. Due to the difficulty in stirring, the stirring time in steps (2) and (3) is increased to 10-15 minutes and 3-5 minutes respectively, to obtain a relatively uniform backfill material.

[0079] The test results of backfill material performance are: expansion 143mm, 7d strength 0.36MPa, 28d strength 0.96MPa, 60d strength 1.22MPa.

[0080] The raw material composition and performance test results of the backfill materials of the above embodiments and comparative examples are summarized in the following table. It can be seen that the backfill materials of Examples 1-4 have both good fluidity and compressive strength, and the 28d strength is significantly increased compared with the 7d strength, and the 60d strength is not much different from the 28d strength, indicating that the strength of the adjustable backfill material can be stably maintained. It can be seen from Examples 2 and 3 that the combined use of the stimulator and the fiber material in the same amount of the density enhancement system has a better effect on improving the strength than the use of the stimulator alone. Comparative Examples 1-3 lack at least one of the fluidity-promoting material system and the density enhancement material system, and the corresponding fluidity or strength is significantly reduced, which is only suitable for engineering scenarios that do not require high overall performance of the backfill material or only require a single performance. Comparative Example 5 uses the three systems of the present invention for clay soil, and the fluidity and strength of the obtained backfill material are far inferior to those of the embodiments, reflecting the applicability of the present invention to low-viscosity engineering waste soil.

[0081]

[0082] This specific implementation is only an explanation of the present invention, not a limitation of the present invention. Any changes made by those skilled in the art after reading the specification of the present invention will be protected by the patent law as long as they are within the scope of the claims of the present invention.

Claims

1. An adjustable backfill material based on low-viscosity fine-grained soil, characterized in that: The following components are included by mass percentage: 65-85% low-viscosity engineering waste soil, 5-10% high-strength solidification material system, 0-1% fluidity-promoting material system, 0-1.5% density-enhancing material system, 5-25% water, the sum of the percentages of each component is 100%; The high-strength solidifying material system includes cement and / or fly ash, the fluidity-promoting material system includes a water reducing agent, and the density-enhancing material system includes an activator and / or a fiber material.

2. The adjustable backfill material based on low-viscosity fine-grained soil according to claim 1, characterized in that: The mass percentage of the fluidity-promoting material system is 0.1-0.8%, and the mass percentage of the density-enhancing material system is 0.3-1.2%.

3. The adjustable backfill material based on low-viscosity fine-grained soil according to claim 1, characterized in that: The cement is selected from one or more of aluminate cement, silicate cement and sulphoaluminate cement.

4. The adjustable backfill material based on low-viscosity fine-grained soil according to claim 1, characterized in that: The water reducer is a polycarboxylate water reducer or a melamine water reducer, and the polycarboxylate water reducer is an early strength type polycarboxylate water reducer, a slow-release type polycarboxylate water reducer or an anti-mud type polycarboxylate water reducer.

5. The adjustable backfill material based on low-viscosity fine-grained soil according to claim 1, characterized in that: The activator is selected from one or more of sodium hydroxide, sodium sulfate, sodium silicate, sodium carbonate, aluminum sulfate slag, desulfurization ash and wood calcium.

6. The adjustable backfill material based on low-viscosity fine-grained soil according to claim 1, characterized in that: The fiber material is one or more of steel fiber, plant fiber, glass fiber and synthetic fiber.

7. The adjustable backfill material based on low-viscosity fine-grained soil according to claim 1, characterized in that: The low-viscosity engineering waste soil is low-viscosity, non-viscosity fine-grained soil or mixed soil, the content of particles with a particle size less than 0.005 mm is less than 20% of the total weight, the content of particles with a particle size greater than 0.075 mm is greater than 40% of the total weight, the proportion of soil particles with a particle size less than 2 cm is greater than 95%, and the maximum particle size is not greater than 10 cm.

8. The method for preparing the adjustable backfill material based on low-viscosity fine-grained soil according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) weighing a high-strength curing material system and a fluidity-promoting material system according to a mass ratio, stirring them in a stirring container, and simultaneously introducing air during the stirring process to uniformly mix the materials into a multi-type mixed material system; (2) Weighing construction waste soil and water in a mass ratio, stirring them in a stirring container to fully mix them into a waste soil suspension; (3) The waste soil suspension and various mixed material systems are mixed and stirred, and finally the density enhancing material system is added and mixed evenly to obtain an adjustable backfill material.

9. The method for preparing an adjustable backfill material based on low-viscosity fine-grained soil according to claim 8, characterized in that: In step (1), the stirring speed is 70-100 rpm and the stirring time is 6-9 minutes.

10. The method for preparing an adjustable backfill material based on low-viscosity fine-grained soil according to claim 8, characterized in that: In step (2), the stirring speed is 80-115 rpm and the stirring time is 5-8 minutes.

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