Nano-excited flow-state solidified soil based on drilling residue soil and preparation method and application of nano-excited flow-state solidified soil

Abstract

The invention discloses nano excitation flow state solidified soil based on drilling muck, which is formed by mixing drilling muck slurry and a curing agent, the doping amount of the curing agent is 6%-12% of the weight of the drilling muck slurry, and the drilling muck slurry is formed by mixing drilling muck and water; wherein the curing agent comprises the following components in percentage by weight: 85%-92% of sulphoaluminate cement, 0.3%-1.0% of an underwater non-dispersing agent, 0.5%-2.0% of a nano early strength agent and 5%-10% of an active mineral admixture; the nanometer early strength agent is a nanometer C-S-H nucleating agent or nanometer lithium carbonate with the particle size smaller than or equal to 100 nm, through efficient excitation of the nanometer C-S-H nucleating agent or nanometer lithium carbonate, the 1d strength of the fluid-state solidified soil can reach 180 kPa, the 2d strength is larger than or equal to 150 kPa, the early strength is improved by 80% or above compared with traditional solidified soil, the transition time of a rotary drilling rig is shortened to 24-48 h, and the construction efficiency is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of fluidized solidified soil. More specifically, this invention relates to a nano-activated fluidized solidified soil based on borehole slag, its preparation method, and its applications. Background Technology

[0002] The shield tunneling method is increasingly widely used in rail transit and subway engineering. Its construction safety, tunneling efficiency, and shield attitude control are directly related to geological conditions. Isolated boulders, which are commonly distributed in coastal granite strata and randomly developed in residual soil, completely weathered / strongly weathered granite, and a small amount of colluvial soil, are prone to problems such as track deviation and cutter wear when the shield passes through them. These problems require precise positioning and step-by-step removal using rotary drilling rigs.

[0003] Rotary drilling rigs generate large amounts of waste soil (including silt, sand, and clay) when dealing with isolated boulders. Traditional disposal methods involve off-site transport and landfilling, which increases costs and creates environmental pressure. Furthermore, the drilling depth is often below the groundwater level, requiring backfilling of the resulting cavities to ensure the safety of subsequent tunneling. Traditional backfill materials (ordinary mortar and underwater concrete) have three major drawbacks: ① They are prone to dispersion and segregation underwater, requiring strict process control; ② They have long setting times (ordinary cement-based materials have a 7-day strength of less than 100 kPa), preventing rapid relocation of rotary drilling rigs and extending the construction period; ③ The core issue of insufficient early strength performance lies in the slow cement hydration reaction rate and lack of an efficient activation mechanism, making it difficult to meet the engineering requirement of "rapidly forming a stable working face."

[0004] Among the existing improvement solutions, conventional soil stabilizers lack underwater anti-dispersion capabilities, and ordinary early-strength agents (such as calcium chloride) have limited improvement effects and are prone to causing durability problems. Neither can simultaneously solve the comprehensive needs of "underwater stability, rapid hardening and early strength, waste utilization, and cost control". Summary of the Invention

[0005] In order to achieve these objectives and other advantages according to the present invention, in one aspect, a preferred embodiment of the present invention provides a nano-activated fluidized solidified soil based on borehole excavation soil, which is made by mixing borehole excavation soil slurry with a solidifying agent, wherein the amount of solidifying agent added is 6%-12% of the weight of the borehole excavation soil slurry, and the borehole excavation soil slurry is made by mixing borehole excavation soil and water. The curing agent, by weight percentage, comprises 85%-92% sulfoaluminate cement, 0.3%-1.0% underwater non-dispersant, 0.5%-2.0% nano early strength agent, and 5%-15% active mineral admixtures. The nano-early strength agent is a nano-CSH nucleating agent with a particle size ≤100nm or nano-lithium carbonate.

[0006] Preferably, the initial fluidity of the solidified fluid is 250~300mm, there is no obvious dispersion after soaking in water for 72h, the unconfined compressive strength is ≥150kPa after 2d, and the unconfined compressive strength is ≥250kPa after 28d.

[0007] Preferably, the particle size of the nano-CSH nucleating agent is 20-50 nm, and the particle size of the nano-lithium carbonate is 50-100 nm.

[0008] Preferably, the underwater non-dispersant is hydrophobically linked polyacrylamide, or a compound of hydroxyethyl methyl cellulose and partially hydrolyzed polyacrylamide in a ratio of 1:1 to 2:1.

[0009] Preferably, the specific gravity of the borehole cuttings mud is 1.45~1.50. The sand content is ≤5%, the colloid content is ≥95%, and the particle size of the borehole slag is ≤40mm.

[0010] Preferably, the active mineral admixture is Grade I fly ash or S95 slag powder.

[0011] On the other hand, a preferred embodiment of the present invention provides a method for preparing the nano-activated fluidized solidified soil based on borehole slag, comprising the following steps: S1. Raw material preparation Collect the borehole debris generated from rotary drilling of isolated boulders for later use; mix sulfoaluminate cement, underwater non-dispersant, nano early strength agent and active mineral admixture in proportion to obtain a curing agent for later use. S2, Pulping The borehole excavation material is mixed with water in a certain proportion to make a homogeneous borehole excavation material slurry. S3, Mixing The drill slag slurry is mixed with a solidifying agent to form a fluid solidified soil that is free from segregation and clumping.

[0012] On the other hand, a preferred embodiment of the present invention provides a method for backfilling rotary drilling holes for handling boulders during shield tunneling, using the aforementioned fluidized solidified soil, comprising the following steps: Step 1: Laying of infusion catheters Lower the grouting pipe into the rotary drilling hole, keeping the bottom of the grouting pipe 300-500mm from the bottom of the hole, and use a sealed quick connection for the pipe joint; Step 2, Continuous Infusion The fluidized solidified soil is continuously pumped into the grouting pipe. During the first grouting, the bottom of the grouting pipe is buried ≥0.8m below the solidified soil surface. During the grouting process, the burial depth of the grouting pipe is controlled at 2~6m. The lifting speed is matched with the grouting speed and controlled at 0.5~1m / h until the grouting reaches 500mm above the design elevation of the borehole. Step 3, Orifice Treatment Remove the laitance from the borehole within 24 hours after grouting and adjust it to the design elevation.

[0013] The present invention has at least the following beneficial effects: (1) Significant rapid hardening effect of nano-activated: This invention enables the fluidized solidified soil to achieve a 1-day strength of 180 kPa and a 2-day strength of ≥150 kPa through efficient activation of nano-CSH nucleating agent or nano-lithium carbonate, which is more than 80% higher than the early strength of traditional solidified soil. The rotation time of rotary drilling rig is shortened to 24~48h, which greatly improves construction efficiency. (2) Material synergistic innovation breakthrough: This invention is the first to create a synergistic system of sulfoaluminate cement, nano activator and composite non-dispersant. The nano early strength agent solves the problem of insufficient early strength, and the composite non-dispersant solves the problem of underwater dispersion. The two complement the main cementitious material, break through the performance contradiction of traditional materials, and have high underwater anti-dispersion properties. (3) Efficient utilization of waste materials: This invention realizes 100% in-situ resource utilization of waste drilling cuttings, reduces the cost of transporting and landfilling the waste soil, saves 800,000 to 1.2 million yuan in disposal costs per 10,000 cubic meters of backfill, and reduces carbon emissions by about 300 tons, which is in line with the concept of green construction. (4) Outstanding cost advantage: This invention does not require additional purchase of aggregates, and the dosage of nano early strength agent is only 0.5%~2.0%. The overall cost is reduced by 35%~45% compared with traditional underwater concrete and by more than 60% compared with chemical grouting. It controls material costs while improving performance. (5) Expanded scope of application: Through the optimization of the compatibility between nano early strength agent and different types of slag soil, this invention can be compatible with a variety of borehole slag soil with sand content of 0~60% and water content of 15%~40%, and is suitable for backfilling of boulders with abundant groundwater and a borehole depth of 10~50m, and is compatible with the construction needs of shield tunneling with different diameters.

[0014] (6) Material synergistic innovation: This invention uses sulfoaluminate cement as the base material and innovatively combines high-performance underwater non-dispersant agent and high-efficiency early strength agent to solve the technical contradiction of traditional materials being easy to disperse underwater and having insufficient early strength performance. This enables the backfill to stand firm in the underwater mud environment and to gain strength quickly, with significant technical advantages.

[0015] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0017] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious modifications will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0018] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0019] A preferred embodiment of the present invention provides a nano-activated fluidized solidified soil based on borehole excavation soil, which is made by mixing borehole excavation soil slurry with a solidifying agent. The amount of solidifying agent added is 6%-12% of the weight of the borehole excavation soil slurry. The borehole excavation soil slurry is made by mixing borehole excavation soil and water. The curing agent, by weight percentage, comprises 85%-92% sulfoaluminate cement, 0.3%-1.0% underwater non-dispersant, 0.5%-2.0% nano-early strength agent, and 5%-10% active mineral admixture; the nano-CSH nucleating agent has a particle size of 20-50 nm, and the nano-lithium carbonate has a particle size of 50-100 nm.

[0020] The nano-early strength agent is a nano-CSH nucleating agent with a particle size ≤100nm or nano-lithium carbonate.

[0021] Drilling excavated soil refers to the mixed waste containing rock fragments and soil particles discharged from underground boreholes during rotary drilling operations involving isolated boulders and other geological formations. Drilling excavated soil slurry is a fluid and stable slurry formed by mixing drilling excavated soil and water in a specific ratio and stirring; the water content in the drilling excavated soil slurry is approximately 45% to 60% by weight. Nano-CSH nucleating agents are hydrated calcium silicate nanoparticles or nano-lithium carbonate with a particle size of 20-50 nm, which can serve as nucleation sites for cement hydration reactions. By providing a large number of nucleation sites through nano-level early-strength agents (such as nano-CSH nucleating agents and nano-lithium carbonate), the activation energy of the hydration reaction is reduced, accelerating the hydration process of cementitious materials and achieving a rapid increase in early strength.

[0022] The initial flowability of the final fluidized solidified soil is 250~300mm, there is no obvious dispersion after soaking in water for 72h, the 2d unconfined compressive strength is ≥150kPa, and the 28d unconfined compressive strength is ≥250kPa.

[0023] In another technical solution, the underwater anti-dispersant is hydrophobically linked polyacrylamide, or a compound of hydroxyethyl methyl cellulose and partially hydrolyzed polyacrylamide in a ratio of 1:1 to 2:1. Hydroxyethyl methyl cellulose is a nonionic cellulose ether with good thickening, water retention, and stabilizing properties, which can increase the viscosity of the slurry and reduce component separation. Partially hydrolyzed polyacrylamide is a product obtained by hydrolysis of polyacrylamide. Its molecular chain contains hydrophilic groups such as carboxyl groups, which have good water solubility and adsorption properties. When used in combination with hydroxyethyl methyl cellulose, it can produce a synergistic effect, further improving the anti-dispersibility of the slurry.

[0024] In another technical solution, the specific gravity of the borehole slurry is 1.45~1.50. The sand content is ≤5%, the colloid content is ≥95%, and the particle size of the borehole slag is ≤40mm. The active mineral admixture is Grade I fly ash or S95 slag powder.

[0025] Another technical solution also provides a method for preparing the nano-activated fluidized solidified soil based on borehole slag, including the following steps: S1. Raw material preparation Collect the borehole debris generated from rotary drilling of isolated boulders for later use; mix sulfoaluminate cement, underwater non-dispersant, nano early strength agent and active mineral admixture in proportion to obtain a curing agent for later use. S2, Pulping The borehole excavation material is mixed with water in a certain proportion to make a homogeneous borehole excavation material slurry. S3, Mixing The drill slag slurry is mixed with a solidifying agent to form a fluid solidified soil that is free from segregation and clumping.

[0026] Another technical solution also provides a method for backfilling rotary drilling holes for handling boulders during shield tunneling, using the aforementioned fluidized solidified soil, including the following steps: Step 1: Laying of infusion catheters Lower the grouting pipe into the rotary drilling hole, keeping the bottom of the grouting pipe 300-500mm from the bottom of the hole, and use a sealed quick connection for the pipe joint; Step 2, Continuous Infusion The fluidized solidified soil is continuously pumped into the grouting pipe. During the first grouting, the bottom of the grouting pipe is buried ≥0.8m below the solidified soil surface. During the grouting process, the burial depth of the grouting pipe is controlled at 2~6m. The lifting speed is matched with the grouting speed and controlled at 0.5~1m / h until the grouting reaches 500mm above the design elevation of the borehole. Step 3, Orifice Treatment Remove the laitance from the borehole within 24 hours after grouting and adjust it to the design elevation.

[0027] This embodiment is applied to the shield tunnel section of the Changle North Tunnel in the Putian-Changle Airport Intercity Railway (F2 Line) project. This section contains a large number of granite boulders, which are treated using rotary drilling to form approximately 1,500 boreholes with a diameter of 1.5m and a depth of 20-30m. Approximately 50,000 cubic meters of fluidized solidified soil needs to be backfilled.

[0028] The specific implementation steps are as follows: 1. Site and Material Preparation: Level a site of approximately 400m² at the construction site, and install a mixing and pumping machine, a 40t curing agent storage tank, and a water tank. Collect and stockpile the excavated soil (mainly a mixture of miscellaneous fill, fine sand, silty clay, and fragmented boulders) generated by the rotary drilling rig for later use.

[0029] 2. Mix Proportion Determination: Through testing, the mix proportion (per cubic meter) of the fluidized solidified soil for this project was determined as follows: approximately 900 kg of borehole slag slurry (specific gravity 1.48), 8% of the slurry weight of the special solidifying agent, and the water-cement ratio was automatically adjusted by the system. Testing showed that the 2-day strength of the fluidized solidified soil under this mix proportion reached 180 kPa, and the 28-day strength reached 300 kPa, meeting the design requirements.

[0030] 3. Mixing and pumping: The excavator feeds the excavated soil into a pulping machine, where it is mixed with water to produce a paste with a specific gravity of 1.48. The mud.

[0031] The mud and solidifying agent are automatically metered and fed into a fully automatic mixing and pumping machine, and continuously mixed by upper and lower double mixing discs to form a uniform fluid solidified soil.

[0032] The equipment comes with a delivery pump, which transports the fluidized solidified soil to the borehole to be backfilled through the laid pump pipe (up to 100m).

[0033] 4. Underwater injection: Lower the guide pipe into the borehole to a position 0.4m from the bottom of the hole.

[0034] Start pumping, and ensure the initial infusion depth of the conduit exceeds 1.0m.

[0035] During the infusion process, a designated person measures the burial depth of the conduit, controlling it within the range of 3-5m, and pulls the conduit out at a uniform speed to ensure continuous and dense infusion.

[0036] 5. Quality inspection: For every 250m³ of fluidized solidified soil produced, a set of 70.7mm×70.7mm×70.7mm test blocks are prepared on site and cured under the same conditions as on site. The test blocks are used to determine the 2d and 28d strength. All test blocks meet the strength standards.

[0037] This method successfully achieved 100% in-situ utilization of waste drill cuttings, ensured stable and reliable backfill quality, improved construction efficiency by about 40% compared to traditional methods, and reduced overall costs by about 35%, providing strong support for the safe and rapid passage of tunnel boring machines through isolated rock areas.

[0038] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0039] The technical effects of the present invention will be explained in detail below through multiple embodiments and comparative examples.

[0040] Example 1: Standard working conditions (abundant groundwater, borehole depth 25m) Type of excavated soil: miscellaneous fill soil + fine sand + silty clay (sand content 30%, moisture content 22%). Curing agent formulation: 90% sulfoaluminate cement, 0.6% HAPAM, 1.2% nano-CSH nucleating agent (40nm particle size), 8.2% fly ash; Construction mix ratio: mud specific gravity 1.48 The curing agent dosage is 10% (based on the dry weight of the soil). Performance results: Initial flowability 280 mm, no dispersion after immersion in water for 72 h; 1-day strength 160 kPa, 2-day strength 245 kPa, 28-day strength 380 kPa; nano-excitation increases the hydration reaction rate by 60%, and ultrasonic testing shows a density of 98%.

[0041] Example 2: Ultra-early stress condition (tight schedule, tunneling needs to be resumed within 24 hours) Type of waste: Strongly weathered granite fragments + clay (25% sand content, 18% moisture content); Curing agent formulation: 92% sulfoaluminate cement, 0.8% HEMC / HPAM compound, 2.0% nano-lithium carbonate (80nm particle size), and 5.2% slag powder; Construction mix ratio: mud specific gravity 1.50 The curing agent content is 12%; Performance results: The nano-lithium carbonate rapidly initiates the hydration reaction, achieving a 1-day strength of 180 kPa and a 2-day strength of 280 kPa, meeting the requirements for 24-hour relocation. The backfill material shows no settlement, and the early strength is 100% higher than that of conventional methods.

[0042] Example 3: High sand content working condition (slag soil with 60% sand content and low clay content) Curing agent formulation: 88% sulfoaluminate cement, 1.0% HAPAM, 1.5% nano-CSH nucleating agent (35nm particle size), 9.5% fly ash; Construction mix ratio: mud specific gravity 1.52 The curing agent dosage is 9%; Performance results: Initial fluidity 260 mm, no segregation; 1-day strength 130 kPa, 2-day strength 215 kPa, 28-day strength 320 kPa; Nano-activator effectively compensates for the slow strength development of high sand content slag soil, with 100% of 2-day strength meeting the standard.

[0043] Example 4: Low-cost operating conditions (lower limit of strength requirements, strict cost control) Curing agent formulation: 87% sulfoaluminate cement, 0.4% HEMC, 0.8% nano-CSH nucleating agent (particle size 50nm), 11.8% fly ash; Construction mix ratio: mud specific gravity 1.46 The curing agent dosage is 8%; Performance results: 1d strength 110kPa, 2d strength 165kPa, 28d strength 260kPa; the nano early strength agent still achieves effective activation at low dosage, and the overall cost is reduced by 18% compared with Example 1, meeting the requirements for foundation backfilling.

[0044] Scale optimization Comparative Example 1 (without nano-early strength agent): The curing agent formulation removed the nano-components, and the rest was the same as in Example 1; Performance results: 1-day strength 55 kPa, 2-day strength 90 kPa, which did not meet the design requirements, and the early strength performance was significantly insufficient; Comparative Example 2 (ordinary early strength agent replacement): 5% calcium chloride was used to replace the nano CSH nucleating agent, and the rest was the same as in Example 1; Performance results: 2-day strength was 130 kPa, underwater dispersion was severe, and the strength of the solidified soil decreased by 20% in the later stage, resulting in poor durability; Comparative Example 3 (insufficient nano-early strength agent): Nano-CSH nucleating agent dosage was 0.3%, and the rest was the same as in Example 1; Performance results: 1-day strength 80 kPa, 2-day strength 120 kPa, insufficient activation effect, unable to meet the requirements for rapid hardening; Comparative Example 4 (Traditional Mortar Backfill): No nano-activation mechanism, 2d strength 80kPa, construction efficiency 35% lower, cost 42% higher.

[0045] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A nano-activated fluidized solidified soil based on borehole slag, characterized in that, It is made by mixing borehole excavation mud with a solidifying agent, wherein the amount of solidifying agent added is 6%-12% of the weight of the borehole excavation mud; The curing agent, by weight percentage, comprises 85%-92% sulfoaluminate cement, 0.3%-1.0% underwater non-dispersant, 0.5%-2.0% nano early strength agent, and 5%-15% active mineral admixtures. The nano-early strength agent is a nano-CSH nucleating agent with a particle size ≤100nm or nano-lithium carbonate.

2. The nano-activated fluidized solidified soil based on borehole slag according to claim 1, characterized in that, The initial flowability of the fluidized solidified soil is 250~300mm, there is no obvious dispersion after soaking in water for 72h, the unconfined compressive strength at 2d is ≥150kPa, and the unconfined compressive strength at 28d is ≥250kPa.

3. The nano-activated fluidized solidified soil based on borehole slag according to claim 1, characterized in that, The particle size of the nano-CSH nucleating agent is 20-50 nm, and the particle size of the nano-lithium carbonate is 50-100 nm.

4. The nano-activated fluidized solidified soil based on borehole slag according to claim 1, characterized in that, The underwater non-dispersant is hydrophobically linked polyacrylamide, or a compound of hydroxyethyl methyl cellulose and partially hydrolyzed polyacrylamide in a ratio of 1:1 to 2:

1.

5. The nano-activated fluidized solidified soil based on borehole slag according to claim 1, characterized in that, The specific gravity of the borehole cuttings mud is 1.45~1.

50. The sand content is ≤5%, the colloid content is ≥95%, and the particle size of the borehole slag is ≤40mm.

6. The nano-activated fluidized solidified soil based on borehole slag according to claim 1, characterized in that, The active mineral admixture is Grade I fly ash or S95 slag powder.

7. A method for preparing nano-activated fluidized solidified soil based on borehole slag as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Raw material preparation Collect the borehole debris generated from rotary drilling of isolated boulders for later use; mix sulfoaluminate cement, underwater non-dispersant, nano early strength agent and active mineral admixture in proportion to obtain a curing agent for later use. S2, Pulping The borehole excavation material is mixed with water in a certain proportion to make a homogeneous borehole excavation material slurry. S3, Mixing The drill slag slurry is mixed with a solidifying agent to form a fluid solidified soil that is free from segregation and clumping.

8. A method for backfilling rotary drilling holes for handling isolated boulders during shield tunneling, characterized in that, Using the fluidized solidified soil according to any one of claims 1-6, the method includes the following steps: Step 1: Laying of infusion catheters Lower the grouting pipe into the rotary drilling hole, keeping the bottom of the grouting pipe 300-500mm from the bottom of the hole, and use a sealed quick connection for the pipe joint; Step 2, Continuous Infusion The fluidized solidified soil is continuously pumped into the grouting pipe. During the first grouting, the bottom of the grouting pipe is buried ≥0.8m below the solidified soil surface. During the grouting process, the burial depth of the grouting pipe is controlled at 2~6m. The lifting speed is matched with the grouting speed and controlled at 0.5~1m / h until the grouting reaches 500mm above the design elevation of the borehole. Step 3, Orifice Treatment Remove the laitance from the borehole within 24 hours after grouting and adjust it to the design elevation.