Fluidified solidified soil for backfilling of nuclear power construction and method for preparing the same
By preparing a fluidized solidified soil by mixing weathered rock and soil, nuclear power solidifying agent and water, the problems of high strength and seismic resistance of the foundation and pit backfill of nuclear power plant buildings and structures were solved, and efficient earthwork disposal and foundation bearing capacity were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGXI FANGCHENGGANG NUCLEAR POWER
- Filing Date
- 2026-02-04
- Publication Date
- 2026-06-05
AI Technical Summary
During the construction of nuclear power plants, it is difficult to find suitable bearing foundations, resulting in an increase in waste soil and rock. Furthermore, existing backfilling methods, such as concrete, are costly and cannot meet earthquake resistance requirements.
Using weathered soil, nuclear power solidifying agent and water as raw materials, fluidized solidified soil is formed by mixing them in a specific ratio. It includes hydraulic cementitious components, composite active reinforcing components and multifunctional additives to ensure high fluidity and high strength, meeting the foundation and pit backfilling requirements of nuclear power plant buildings and structures.
It provides high mechanical properties and corrosion resistance, with a foundation bearing capacity of over 350 kPa and a shear wave velocity of over 300 m/s, reducing foundation settlement and meeting the seismic requirements of nuclear power plants.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of construction waste backfilling technology, and in particular to a fluidized solidified soil for backfilling nuclear power plant construction structures and its preparation method. Background Technology
[0002] With the accelerated pace of nuclear power plant construction in recent years and the increasingly complex geological conditions of nuclear power plant construction sites, it has become increasingly difficult to find suitable bearing foundations for conventional islands, auxiliary structures, and even the nuclear island. This leads to a significant increase in excavation volume, generating substantial amounts of waste soil and rock, raising both environmental and economic concerns regarding waste disposal. Simultaneously, substantial foundation and pit backfilling works are required, with existing methods often employing concrete backfilling. If soil stabilization technology could be used to process waste soil and rock into building materials suitable for foundation and pit backfilling, this problem in the nuclear power plant construction process would be effectively solved.
[0003] Currently, fluidized solidified soil is mainly used in foundation trench backfilling, but its application in bearing strata is relatively limited. For nuclear power engineering, some foundations not only have conventional static load requirements but also seismic resistance requirements. Therefore, fluidized solidified soil suitable for the foundations and pit backfilling of nuclear power plant buildings is necessary. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide a fluidized solidified soil for backfilling nuclear power plant structures and its preparation method.
[0005] The technical solution adopted by the present invention to solve its technical problem is: to provide a fluidized solidified soil for backfilling nuclear power plant buildings, comprising the following raw materials and their mass fractions as follows: 50-70 parts weathered rock and soil, 6-10 parts nuclear power solidification agent and 25-35 parts water; The nuclear power curing agent comprises 25-40% hydraulic cementitious component, 45-65% composite active reinforcing component, 8-15% composite activating component, and 2-6% multifunctional auxiliary component.
[0006] The weathered rock and soil are at least one of the following: crushed strongly weathered mudstone and shale, strongly weathered silty mudstone, and strongly weathered rock; the particle size of the weathered rock and soil is ≤20mm.
[0007] Preferably, the hydraulic cementitious component comprises sulfoaluminate cement clinker and silicate cement clinker in a mass ratio of 1:1 to 1:3, and is externally mixed with desulfurized gypsum accounting for 5% to 15% of the total mass of the hydraulic cementitious component as a setting regulator.
[0008] Preferably, the composite active enhancement component is formed by combining highly active mineral micro powder and moderately active industrial waste residue powder in a mass ratio of 1:2 to 2:1; the fineness requirement of the composite active enhancement component is that the residue on a 45-micron square hole sieve is no more than 5%.
[0009] The highly active mineral powder is silica fume or ultrafine calcined kaolin with a specific surface area of not less than 600 m² / kg; the medium-active industrial waste residue powder is selected from at least one of S95 grade mineral powder, selected fly ash, and red mud powder, and its 28-day activity index is not less than 70%.
[0010] Preferably, the composite activating component consists of a chemical activator and a physical structure forming agent; wherein the chemical activator is a mixture of water glass with a modulus of 1.0-1.8 and anhydrous sodium sulfate in a mass ratio of 3:1 to 5:1; and the physical structure forming agent is micron-sized calcined diatomaceous earth with a specific surface area of not less than 700 m² / kg.
[0011] Preferably, the multifunctional additive components include a viscosity-reducing polycarboxylate superplasticizer, a surfactant VAE, a stabilizer, and a water-retaining agent.
[0012] The viscosity-reducing polycarboxylate superplasticizer accounts for 60%-80% of the mass of the multifunctional additive components; the stabilizer is xanthan gum; and the water-retaining agent is nonionic cellulose ether.
[0013] Preferably, the fluidity of the solidified soil is 200mm to 300mm, and after 28 days of solidification and stabilization, the unconfined compressive strength is ≥0.6MPa, and the permeability coefficient is ≤1×10⁻⁶. -7 cm / s, the foundation bearing capacity can be higher than 350kPa, and the shear wave velocity is greater than 300m / s.
[0014] This invention also provides a method for preparing fluidized solidified soil, comprising the following steps: S1. Mix the nuclear power curing agent and water thoroughly and stir evenly to form a curing agent slurry; S2. Mix the curing agent slurry with weathered rock and soil and water and stir evenly until the set standard is reached to obtain fluidized solidified soil; the set standard is: the variation index of the torque of the main shaft of the mixing equipment does not exceed 0.1 under high-speed stirring conditions of not less than 40 rpm.
[0015] Preferably, in step S1, the mass ratio of the nuclear power curing agent to water is 1:1 to 1:2.
[0016] Preferably, the method for preparing the fluidized solidified soil further includes the following steps: S0. Pretreatment of weathered soil and rock; The blocky, strongly weathered argillaceous shale is crushed into particles of 1cm to 2cm using a crushing device, wherein the three-dimensional spindle speed of the crushing device is not less than 80 rpm.
[0017] The beneficial effects of this invention are as follows: The fluidized solidified soil of this invention has high mechanical properties, corrosion resistance and dynamic properties, and is suitable for the foundation and pit backfill of nuclear power plant buildings and structures. As a replacement foundation, its bearing capacity can reach more than 350 kPa and its shear wave velocity can reach more than 300 m / s, which can meet the performance requirements of the foundation replacement of nuclear power plant buildings and structures and reduce the permanent settlement of the foundation of buildings and structures under static load or strong earthquake. Detailed Implementation
[0018] The fluidized solidified soil for backfilling nuclear power plant structures according to one embodiment of the present invention comprises the following raw materials and their mass fractions: 50-70 parts weathered rock and soil, 6-10 parts nuclear power solidification agent, and 25-35 parts water.
[0019] Among them, weathered rock and soil, as the base material for fluidized solidified soil, are preferably at least one of crushed strongly weathered mudstone and shale, strongly weathered silty mudstone, and strongly weathered rock. The weathered rock and soil are granular with a particle size ≤20mm, and a particle size range of 10mm to 20mm is further preferred.
[0020] The nuclear power plant curing agent is formed by mixing multiple components, and the components and their mass percentages are as follows: hydraulic cementitious component 25-40%, composite active reinforcing component 45-65%, composite activating component 8-15%, and multifunctional auxiliary component 2-6%. The hydraulic cementitious component acts as the reaction core, providing early strength and a micro-expansion framework; the composite active reinforcing component acts as a micro-filler and source of long-term strength, optimizing particle size distribution and improving density; the composite activating component continuously stimulates the potential activity of the former two through a dual chemical and physical mechanism and achieves internal curing, ensuring stable strength development; while the multifunctional auxiliary component precisely controls the rheological state of the entire system on a macroscopic level, ensuring high fluidity and homogeneity, providing a guarantee for the full progress of the micro-reaction and the final formation of a high-modulus, high-damping dense structure.
[0021] The hydraulic cementitious component comprises sulfoaluminate cement clinker and silicate cement clinker in a mass ratio of 1:1 to 1:3, with 5% to 15% desulfurized gypsum added as a setting regulator. The hydraulic cementitious component is mainly composed of sulfoaluminate cement clinker and silicate cement clinker in a specific ratio. It has high activity, a fast reaction rate, and produces a large amount of hydration products. Furthermore, the low-to-medium activity of the composite active component enhances the early reaction environment, stimulating the production of more hydration products in the later stages of the hydration reaction. To maintain the early fluidity of the solidified soil, 5%-15% desulfurized gypsum is added as a setting regulator to prevent excessively rapid early setting of the solidified soil and to provide a sulfur source for the micro-expansion of the solidified soil.
[0022] The composite active reinforcing component is formed by combining highly active mineral micro powder and moderately active industrial waste residue powder at a mass ratio of 1:2 to 2:1. This composite active reinforcing component is a major component of the nuclear power plant solidification agent. While this material is low in cost and has low early-stage activity, it provides more aluminum, silicon, and calcium source substances, and its fineness is high. It exhibits a significant pozzolanic reaction in the later stages of the hydration reaction, steadily improving long-term strength and enhancing the flowability of the solidification agent. The fineness requirement for the composite active reinforcing component is that the residue on a 45-micron square-hole sieve should not exceed 5% to ensure its activity and reaction efficiency, while also improving the uniformity of the solidified soil material formed by the reaction.
[0023] Furthermore, the highly active mineral powder is silica fume or ultrafine calcined kaolin with a specific surface area of not less than 600 m² / kg; the moderately active industrial waste residue powder is selected from at least one of S95 grade mineral powder, selected fly ash, and red mud powder, with a 28-day activity index of not less than 70%. Increasing the specific surface area ensures the activity and reaction efficiency of the highly active mineral powder, while also improving the uniformity of the solidified soil material formed by the reaction.
[0024] The composite activation component consists of a chemical activator and a physical structure forming agent. The main components are anhydrous sodium sulfate and diatomaceous earth, which achieve sulfate activation, react with hydrated aluminum to generate more ettringite, and the porous structure of the diatomaceous earth can adsorb some water and activator, releasing them slowly in the later stages, thus providing internal maintenance and continuous activation. Specifically, the chemical activator is a mixture of water glass with a modulus of 1.0-1.8 and anhydrous sodium sulfate in a mass ratio of 3:1 to 5:1; the physical structure forming agent is micron-sized calcined diatomaceous earth with a specific surface area of not less than 700 m² / kg to ensure the water adsorption capacity of the diatomaceous earth.
[0025] The multifunctional additive components include a viscosity-reducing polycarboxylate superplasticizer, a surfactant, a stabilizer, and a water-retaining agent. The viscosity-reducing polycarboxylate superplasticizer achieves water reduction and dispersion effects, ensuring the high fluidity of the fluidized solidified soil while maintaining its high density, thus facilitating the achievement of high modulus and high wave velocity in the solidified soil. VAE forms a polymer film in the fluidized solidified soil slurry, bridging microcracks, enhancing the interfacial transition zone, and significantly improving the material's toughness and crack resistance. The stabilizer xanthan gum ensures the macroscopic and microscopic homogeneity of the cast body. The water-retaining agent, nonionic cellulose ether, ensures full hydration of all cementitious materials and provides appropriate viscosity, preventing plastic shrinkage cracking and ensuring full strength development. The viscosity-reducing polycarboxylate superplasticizer accounts for 60%-80% of the multifunctional additive components by mass. The surfactant VAE accounts for 8%-18% of the multifunctional additive components by mass, used to enhance interfacial adhesion between particles and crack resistance. The stabilizer, xanthan gum, accounts for 2%-6% of the mass of the multifunctional additive components. Its main function is to lock in the moisture of the fluidized solidified soil, prevent segregation, and maintain the stability of the fluidized solidified soil. The water-retaining agent, a non-ionic cellulose ether, accounts for 10%-20% of the mass of the multifunctional additive components.
[0026] The water used in the raw materials is industrial water. Seawater can also be used when industrial water is insufficient.
[0027] In the preparation of the fluidized solidified soil of the present invention, the raw materials can be mixed evenly by a sealed high-power mixing device to form a fluid and stable self-flowing filling slurry for use in foundation and pit backfilling.
[0028] The fluidity of the solidified soil of this invention is 200mm~300mm, and after 28 days of solidification and stabilization, the unconfined compressive strength is ≥0.6MPa, and the permeability coefficient is ≤1×10⁻⁶. -7 cm / s, the foundation bearing capacity can be higher than 350kPa, and the shear wave velocity is greater than 300m / s.
[0029] A method for preparing fluidized solidified soil according to an embodiment of the present invention may include the following steps: S0. Pretreatment of weathered soil and rock.
[0030] The crushing equipment breaks down the blocky, strongly weathered argillaceous shale into particles of 1cm to 2cm. The three-dimensional spindle speed of the crushing equipment is not less than 80 rpm.
[0031] S1. Premix the nuclear power curing agent and water, stirring thoroughly until homogeneous. The mass ratio of the nuclear power curing agent to water should be 1:1 to 1:2. After stirring, a curing agent slurry will be formed. Let it stand for later use. The standing time for the curing agent slurry should not exceed 30 minutes.
[0032] S2. Mix the curing agent slurry with weathered soil and water, and stir evenly until the set standard is reached to obtain fluidized solidified soil. The set standard is: the variation index of the main shaft torque of the mixing equipment does not exceed 0.1 under high-speed mixing conditions of not less than 40 rpm.
[0033] The present invention will be further described below through specific embodiments.
[0034] Example 1: Soil crushing: Specialized crushing equipment with a spindle speed of not less than 80 rpm is used to crush strongly weathered silty mudstone to form soil with a maximum particle size of ≤20mm.
[0035] Preparation of fluidized solidified soil: The nuclear power plant solidifying agent consists of 30% hydraulic cementitious components, 54% composite active reinforcing components, 12% composite activating components, and 4% multifunctional auxiliary components; the fluidized solidified soil contains 56.2 parts soil, 34.5 parts water, and 9.3 parts nuclear power plant solidifying agent, resulting in a wet density of 1.723 g / m³. 3 The flow spread is 165mm, which meets the requirements for self-leveling and vibration-free pouring during construction. The 28-day unconfined compressive strength is 1.435MPa. Triaxial static shear tests, based on the Duncan EB model parameters, yielded a static shear modulus K of 2795.3 and an exponent n of 0.272. Dynamic triaxial tests yielded a maximum dynamic shear modulus of 8168 and an exponent of 0.031. Dynamic permanent deformation tests yielded improved permanent deformation parameters for the Shenzhujiang concrete (c1 is a parameter related to the volumetric strain amplitude, c2 is an exponent of volumetric strain changing with stress level, c3 is an exponent of volumetric strain changing with the number of cycles, c4 is a parameter related to the shear strain amplitude, and c5 is an exponent of shear strain changing with stress level), indicating small permanent deformation under seismic conditions in the fluidized solidified soil.
[0036] Table 1. Permanent deformation parameters of the fluidized solidified soil obtained in Example 1 Example 2: Soil crushing: Specialized crushing equipment with a spindle speed of not less than 80 rpm is used to crush strongly weathered silty mudstone to form soil with a maximum particle size of ≤20mm.
[0037] Preparation of fluidized solidified soil: The nuclear power plant solidifying agent consists of 32% hydraulic cementitious components, 50% composite active reinforcing components, 13% composite activating components, and 5% multifunctional auxiliary components; the fluidized solidified soil contains 62.5 parts soil, 28.2 parts water, and 9.3 parts nuclear power plant solidifying agent, resulting in a wet density of 1.753 g / m³. 3The flow spread is 180mm, which meets the requirements for self-leveling and vibration-free construction. The 28-day unconfined compressive strength is 1.435MPa. Triaxial static shear tests, based on the Duncan EB model parameters, show a static shear modulus K of 3597.5 and an exponent n of 0.210. Dynamic triaxial tests yielded a maximum dynamic shear modulus of 12576 and an exponent of 0.052. Dynamic permanent deformation tests yielded improved permanent deformation parameters for the Shenzhujiang concrete, indicating small seismic permanent deformation in the fluidized solidified soil.
[0038] Table 2. Permanent deformation parameters of the fluidized solidified soil obtained in Example 2 Taking Example 2 as an example, in-situ tests were conducted on the fluidized solidified soil prepared in Example 2: In accordance with the backfilling requirements for the nuclear power plant's pipe gallery, a foundation pit with a plan dimension of 7m × 10m and a depth of 4m was excavated. The excavation surface of the foundation was strongly weathered silty mudstone. The fluidized solidified soil of Example 2 was used for the foundation and the foundation pit backfilling. After reaching the 28-day unconfined compressive strength, in-situ tests were conducted. The characteristic value of the foundation bearing capacity was found to be greater than 350kPa through the plate load test. The shear wave velocity of the fluidized solidified soil was found to be 362m / s to 368m / s through the single-hole shear wave velocity test. The backfilled site can meet the basic design requirements of the nuclear power plant's seismic resistance.
[0039] Comparative Example 1: Soil crushing: Specialized crushing equipment with a spindle speed of not less than 80 rpm is used to crush strongly weathered silty mudstone to form soil with a maximum particle size of ≤20mm.
[0040] Preparation of fluidized bed solidified soil: Ordinary Portland cement P.0 42.5 was used to replace the nuclear power plant solidifying agent. The fluidized bed solidified soil consisted of 56.2 parts soil, 34.5 parts water, and 9.3 parts cement, resulting in a wet density of 1.724 g / m³. 3 Flow spread 170mm, 28d unconfined compressive strength 0.819MPa.
[0041] The above comparison shows that the strength performance of the fluidized solidified soil prepared in Comparative Example 1 is significantly lower than that of the fluidized solidified soil prepared in Examples 1 and 2, resulting in the mechanical properties of the replacement foundation being worse than those in Examples 1 and 2.
[0042] It is understood that the above embodiments are only some representative embodiments of the present invention. When the raw materials of the fluidized solidified soil of the present invention are used in other mass parts within a limited range, they can also achieve high mechanical properties, corrosion resistance and dynamic properties. As a replacement foundation, the bearing capacity can reach more than 350 kPa and the shear wave velocity can reach more than 300 m / s, which can meet the performance requirements of the foundation replacement of nuclear power plant buildings and reduce the permanent settlement of the foundation of buildings under static load or strong earthquake.
[0043] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.
Claims
1. A fluidized solidified soil for backfilling nuclear power plant structures, characterized in that, The raw materials and their mass fractions are as follows: 50-70 parts weathered rock and soil, 6-10 parts nuclear power solidification agent, and 25-35 parts water; The nuclear power curing agent comprises 25-40% hydraulic cementitious component, 45-65% composite active reinforcing component, 8-15% composite activating component, and 2-6% multifunctional auxiliary component.
2. The fluidized solidified soil according to claim 1, characterized in that, The weathered rock and soil are at least one of the following: crushed strongly weathered mudstone and shale, strongly weathered silty mudstone, and strongly weathered rock; the particle size of the weathered rock and soil is ≤20mm.
3. The fluidized solidified soil according to claim 1, characterized in that, The hydraulic cementitious component comprises sulfoaluminate cement clinker and silicate cement clinker in a mass ratio of 1:1 to 1:3, and is externally mixed with desulfurized gypsum accounting for 5% to 15% of the total mass of the hydraulic cementitious component as a setting regulator.
4. The fluidized solidified soil according to claim 1, characterized in that, The composite active enhancement component is formed by combining highly active mineral micro powder and moderately active industrial waste residue powder at a mass ratio of 1:2 to 2:1; the fineness requirement of the composite active enhancement component is that the residue on a 45-micron square hole sieve is no more than 5%; The highly active mineral powder is silica fume or ultrafine calcined kaolin with a specific surface area of not less than 600 m² / kg; the medium-active industrial waste residue powder is selected from at least one of S95 grade mineral powder, selected fly ash, and red mud powder, and its 28-day activity index is not less than 70%.
5. The fluidized solidified soil according to claim 1, characterized in that, The composite activating component consists of a chemical activator and a physical structure forming agent; wherein, the chemical activator is a mixture of water glass with a modulus of 1.0-1.8 and anhydrous sodium sulfate in a mass ratio of 3:1 to 5:1; and the physical structure forming agent is micron-sized calcined diatomaceous earth with a specific surface area of not less than 700 m² / kg.
6. The fluidized solidified soil according to claim 1, characterized in that, The multifunctional additive components include a viscosity-reducing polycarboxylate superplasticizer, a surfactant VAE, a stabilizer, and a water-retaining agent; The viscosity-reducing polycarboxylate superplasticizer accounts for 60%-80% of the mass of the multifunctional additive components; the stabilizer is xanthan gum; and the water-retaining agent is nonionic cellulose ether.
7. The fluidized solidified soil according to any one of claims 1-6, characterized in that, The fluidity of the solidified soil is 200mm to 300mm, and after 28 days of solidification and stabilization, its unconfined compressive strength is ≥0.6MPa, and its permeability coefficient is ≤1×10⁻⁶. -7 cm / s, the foundation bearing capacity can be higher than 350kPa, and the shear wave velocity is greater than 300m / s.
8. A method for preparing the fluidized solidified soil according to claim 1, characterized in that, Includes the following steps: S1. Mix the nuclear power curing agent and water thoroughly and stir evenly to form a curing agent slurry; S2. Mix the curing agent slurry with weathered rock and soil and water and stir evenly until the set standard is reached to obtain fluidized solidified soil; the set standard is: the variation index of the torque of the main shaft of the mixing equipment does not exceed 0.1 under high-speed stirring conditions of not less than 40 rpm.
9. The method for preparing fluidized solidified soil according to claim 8, characterized in that, In step S1, the mass ratio of the nuclear power curing agent to water is 1:1 to 1:
2.
10. The method for preparing fluidized solidified soil according to claim 8 or 9, characterized in that, It also includes the following steps: S0. Pretreatment of weathered soil and rock; The blocky, strongly weathered argillaceous shale is crushed into particles of 1cm to 2cm using a crushing device, wherein the three-dimensional spindle speed of the crushing device is not less than 80 rpm.