Grouting reinforcement material for broken water-containing surrounding rock and construction process

Abstract

The invention relates to the technical field of geotechnical engineering reinforcement, and discloses a broken water-containing surrounding rock grouting reinforcement material and a construction technology.The reinforcement material comprises a component A and a component B. The component A comprises a sodium silicate aqueous solution, a catalyst and a surfactant, and the component B is a polyisocyanate prepolymer. The component B and the component A are subjected to a polymerization reaction to prepare a prepolymer, the prepolymer reacts with water in the environment to produce a water-insoluble consolidated body with certain elasticity and strength, and after a sodium silicate aqueous solution in the component A loses water, the water-insoluble consolidated body is added into the water-soluble consolidated body to form the water-soluble consolidated body. And the NCO group contained in the polymerized diphenylmethane diisocyanate not only can react with the OH group of the polyether polyol and water, but also can be self-polymerized. Polyurethane long chains are filled with the grouting material, and the sodium silicate aqueous solution polyurethane grouting material is low in cost, flame-retardant in nature and capable of achieving a good reinforcing effect.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering reinforcement technology, specifically to a grouting reinforcement material and construction process for fractured water-bearing surrounding rock. Background Technology

[0002] Currently, with the improvement of coal mining capacity, the increase in mining depth of old mines, and the widespread application of fully mechanized top coal caving mining technology, the number and distribution range of coal mines with extremely broken and water-bearing surrounding rock conditions are increasing and expanding year by year. These types of surrounding rock have poor stability and are extremely prone to collapse. Without measures such as advanced reinforcement and filling of high-collapse areas, normal mining and tunneling cannot be carried out. Although polymer grouting materials have characteristics such as fast curing, high strength, and good permeability, they are expensive when used alone and have insufficient flame retardancy, making it difficult to meet the reinforcement needs of extremely broken and water-bearing surrounding rock.

[0003] According to the research, the existing defects of grouting reinforcement materials are:

[0004] 1. In patent document CN113860835B, although the powder material has good strength and flame retardancy, its underwater stability and long-term durability under extremely crushed and high moisture content conditions may be insufficient. In addition, its composition is complex and has high requirements for the purity of raw materials, which may affect the convenience of on-site construction and cost control.

[0005] 2. In patent document CN205370587U, the problems of outer tube collapse and grouting uniformity during the grouting process are solved by the structure of grouting pipe and outer tube, but the performance optimization of the grouting material itself is not involved.

[0006] 3. In patent document CN116285374A, although the grouting material is designed in layers to address water damage to the roof, its preparation process is complicated, involves multiple chemical synthesis steps, has high cost, and has stringent requirements for construction conditions, making it difficult to promote and apply on a large scale in complex and variable downhole environments.

[0007] 4. In patent document CN112341118A, a grouting material for the base plate with cement, mineral powder, desulfurized gypsum and other main raw materials is proposed. However, it is mainly for the reinforcement of the base plate and has limited effect on the penetration and reinforcement of the extremely broken surrounding rock of the top plate. Moreover, there is still room for improvement in terms of rapid setting and high strength.

[0008] How to simultaneously address multiple challenges in grouting materials under fractured and water-bearing conditions, such as high permeability, high strength, rapid curing, good underwater stability, excellent flame retardancy, low cost, and ease of construction, is a key technical problem that urgently needs to be solved in current coal mine underground rock reinforcement technology. Summary of the Invention

[0009] This invention provides a grouting reinforcement material and construction process for fractured water-bearing surrounding rock, in order to solve the technical problems mentioned in the background art, such as low permeability, low strength, slow curing speed, poor underwater stability, and high cost of existing materials.

[0010] This invention provides a grouting reinforcement material and construction process for fractured water-bearing surrounding rock. The reinforcement material comprises component A and component B, wherein:

[0011] Component A contains an aqueous solution of sodium silicate, a catalyst, and a surfactant;

[0012] Component B is a polyisocyanate prepolymer, specifically composed of prepolymerized diphenylmethane diisocyanate and polyether polyol, with the addition of a plasticizer.

[0013] The polymerization reaction of component B and component A produces a prepolymer. The prepolymer reacts with water in the environment to produce a solid that is insoluble in water and has a certain elasticity and strength. After the sodium silicate aqueous solution in component A loses water, it solidifies into a high-strength solid and fills the spaces between the long polyurethane chains. The NCO group contained in the polymerized diphenylmethane diisocyanate can not only react with the OH group of the polyether polyol and water, but also can self-polymerize.

[0014] The reaction mechanism is as follows:

[0015] 1-1. Reaction of isocyanate and hydroxyl group: RN=C=O+R'-OH→RNHCOOR;

[0016] 1-2. Reaction of isocyanate with water: 2R-N=C=O+H2O→RNHCONHR+CO2↑;

[0017] 1-3. Urea carbamate reaction: RN=C=O + R'NHCOOR” → RNHCOR'NCOOR”;

[0018] 1-4. Biuret reaction: RN=C=O+R'NHCONHR'→RNHCOR'NCONHR.

[0019] Preferably, the concentration of sodium silicate aqueous solution in component A is controlled, and the mass fraction of sodium silicate aqueous solution is limited to 30% to 40% to avoid excessive water triggering a large number of reactions 1-2. A desiccant is added to component A to adsorb free water in the environment and reduce the side reaction between NCO and water. The desiccant can be anhydrous calcium chloride.

[0020] Preferably, the structure of component B prepolymer is adjusted by prepolymerizing a high-functionality polyether polyol with a polyisocyanate prepolymer, increasing the competitive priority of -NCO and -OH in reaction 1-1, reducing the proportion of reaction 1-2, and reducing CO2 generation from the source. The high-functionality polyether polyol can be selected as a 4-functionality polyether.

[0021] Preferably, an organosilicon defoamer is added to component A to inhibit the formation and growth of CO2 bubbles in reaction 1-2. The organosilicon defoamer can be selected as polydimethylsiloxane.

[0022] Preferably, the catalyst in component A is a combination of a main catalyst and a retarder:

[0023] The main catalyst ensures the final reaction is complete; the main catalyst can be dibutyltin dilaurate.

[0024] The delay agent inhibits the reaction in the early stage of grouting, ensuring that the grout has enough time to flow. After penetrating into the micro-cracks, the delay agent gradually becomes ineffective, and the reaction accelerates the solidification. The delay agent can be benzoyl chloride or phosphate ester.

[0025] Preferably, the amount of catalyst is increased in a low-temperature environment (<5°C), or an antifreeze is added to component A to lower the freezing point of the slurry and ensure reaction activity. The amount of catalyst is increased by 10% to 20% higher than at room temperature. The antifreeze can be ethylene glycol.

[0026] Preferably, when mixing component A and component B, a sodium silicate aqueous solution is treated with a silane coupling agent. The amino / epoxy groups of the coupling agent react with the polyurethane in component B through urea bond reaction. The siloxane groups in the silane coupling agent can combine with the SiO2 in the sodium silicate aqueous solution to form an organic-inorganic bridge, reducing phase separation.

[0027] Preferably, nano-SiO2 and nano-TiO2 can be added to component A, with a mass fraction of 1% to 3%. The nanoparticles can fill the interfacial gap between the sodium silicate aqueous solution and polyurethane, enhancing the interfacial bonding force. At the same time, the high specific surface area of ​​the nanoparticles can adsorb surfactants.

[0028] Preferably, when mixing component A and component B, or by treating the sodium silicate aqueous solution with fluorosilane, a hydrophobic layer is formed on the SiO2 surface through modification treatment, reducing the penetration of water and acid.

[0029] Glass fiber or basalt fiber is added to component A. Sodium silicate forms a continuous Si-O-Si three-dimensional gel matrix through hydrolysis and condensation under the action of a catalyst. Surfactant ensures that the fiber is uniformly dispersed and bonded to the matrix. Glass fiber / basalt fiber is embedded in the matrix through physical interweaving and chemical adsorption, together forming a stable and high-strength three-dimensional structure that blocks the contact between acid and sodium silicate aqueous solution, while enhancing the crack resistance of the solidified body.

[0030] Preferably, the construction process steps for grouting reinforcement materials are as follows:

[0031] S1. Drilling: The initial grouting depth is set at 15 to 20m. All holes will be vertical with an opening diameter of 130mm. When drilling into bedrock, the hole diameter can be appropriately reduced, but not less than 91mm. Drill to a depth of 0.5m into bedrock and use casing for wall protection. If a karst cave is encountered at the predetermined depth, drilling should continue to 1.0m below the bottom of the karst cave.

[0032] S2. Slurry preparation: A combination of static mixer and dynamic stirring is adopted. A static mixer is installed at the front end of the grouting pipe to ensure that components A and B are fully mixed during transportation. The storage tanks of components A and B are equipped with low-speed stirring devices to avoid sedimentation of sodium silicate aqueous solution and stratification of prepolymer.

[0033] S3. Grouting pressure: Generally, it should be no less than 0.1 to 0.3 MPa in bedrock, gradually increasing to 0.3 to 0.5 MPa at the rock-soil interface, with a maximum of 1.0 MPa. During construction, the grouting pressure should be adjusted according to the grouting situation, and the grouting pump flow rate should be 38 to 90 L / min.

[0034] S4. Grouting Completion Criteria: Grouting can be terminated when one of the following criteria is met:

[0035] ①The pressure at the grouting pipe orifice rises to above 0.5MPa and remains stable for 15 minutes;

[0036] ②The pressure at the grouting pipe orifice did not reach 0.5MPa, but the grouting rate was less than 5L / min and lasted for 15 minutes;

[0037] ③ The bedrock of the grouting borehole is intact, or multiple grouting operations are performed, and the borehole pressure exceeds 1.0 MPa;

[0038] ④ The grout leakage point has extended 3 to 5 meters beyond the grouting range;

[0039] ⑤ When the grouting volume in a single hole reaches 1.5 to 2.0 times the average grouting volume, and the grout absorption volume decreases significantly;

[0040] If the above standards are not met, the hole should be cleaned and grouting should be repeated.

[0041] S5. Grout diffusion radius: Grout diffusion radius is an important parameter in grouting treatment. However, due to the extremely uneven development of karst in both vertical and horizontal directions, it is difficult to obtain a representative grout diffusion radius applicable to the entire stratum, whether through theoretical calculation or grouting test. Based on the experience of grouting treatment projects, the diffusion radius in bedrock can be considered as 3.5m, and the diffusion radius in Quaternary can be considered as 0.75m.

[0042] Compared with the prior art, the beneficial effects of the present invention are:

[0043] Compared to ordinary roof grouting materials, sodium silicate aqueous solution-polyurethane grout is a prepolymer prepared by the polymerization reaction of polyisocyanate and polyhydroxy compound. It reacts with sodium silicate aqueous solution and water in the environment to produce a solidified body that is insoluble in water and has a certain elasticity and strength. After the sodium silicate aqueous solution loses water, it solidifies into a high-strength solid, which fills the spaces between the long chains of polyurethane and plays a role in solidification. Sodium silicate aqueous solution polyurethane grout has a low cost, is inherently flame retardant, and can achieve good reinforcement effect in most cases.

[0044] Furthermore, in flowing water, sodium silicate aqueous solution polyurethane grout will not be diluted or dissolved, and its solidified body has high strength. Therefore, it can still play a good reinforcing role in the presence of water. The -NCO group contained in MDI or TDI can not only react with the -OH group of polyether polyol in component A and water, but also can self-polymerize. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the cross-sectional structure of the grouting face of the present invention;

[0046] Figure 2 This is a schematic diagram of the working face grouting planar structure of the present invention. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] Example 1

[0049] A grouting reinforcement material for fractured water-bearing surrounding rock comprises: component A and component B, wherein:

[0050] Component A contains an aqueous solution of sodium silicate, a catalyst, and a surfactant;

[0051] Component B is a polyisocyanate prepolymer, specifically composed of prepolymerized diphenylmethane diisocyanate and polyether polyol, with the addition of a plasticizer.

[0052] Component B reacts with Component A to produce a prepolymer. The prepolymer reacts with water in the environment to produce a solid that is insoluble in water and has a certain elasticity and strength. After losing water, the sodium silicate aqueous solution in Component A solidifies into a high-strength solid, which fills the spaces between the polyurethane long chains and acts as a solidifying agent. The NCO group contained in the polymerized diphenylmethane diisocyanate can not only react with the OH group of the polyether polyol and water, but also can self-polymerize.

[0053] The reaction mechanism is as follows:

[0054] 1-1. Reaction of isocyanate and hydroxyl group: RN=C=O+R'-OH→RNHCOOR;

[0055] 1-2. Reaction of isocyanate with water: 2R-N=C=O+H2O→RNHCONHR+CO2↑;

[0056] 1-3. Urea carbamate reaction: RN=C=O + R'NHCOOR” → RNHCOR'NCOOR”;

[0057] 1-4. Biuret reaction: RN=C=O+R'NHCONHR'→RNHCOR'NCONHR.

[0058] It should be noted that the concentration of sodium silicate aqueous solution in component A should be controlled, and the mass fraction of sodium silicate aqueous solution should be limited to 30% to 40% to avoid excessive water triggering a large number of reactions 1-2. A desiccant should be added to component A to adsorb free water in the environment and reduce the side reaction between NCO and water. Anhydrous calcium chloride can be selected as the desiccant.

[0059] It is important to note that by adjusting the structure of the prepolymer of component B and using a high-functionality polyether polyol and a polyisocyanate prepolymer, the competitive priority between -NCO and -OH in reaction 1-1 is increased, the proportion of reaction 1-2 is reduced, and the amount of CO2 generated is reduced from the source. The high-functionality polyether polyol can be selected as a 4-functionality polyether.

[0060] Furthermore, an organosilicone defoamer can be added to component A to inhibit the formation and growth of CO2 bubbles in reaction 1-2. The organosilicone defoamer can be selected as polydimethylsiloxane.

[0061] It should be noted that the catalyst in component A is a combination of a main catalyst and a retarder:

[0062] The main catalyst ensures the final reaction is complete; the main catalyst can be dibutyltin dilaurate.

[0063] The delay agent inhibits the reaction in the early stage of grouting, ensuring that the grout has enough time to flow. After penetrating into the micro-cracks, the delay agent gradually becomes ineffective, and the reaction accelerates the solidification. The delay agent can be benzoyl chloride or phosphate ester.

[0064] It should be noted that in low-temperature environments (<5℃), the amount of catalyst can be increased, or an antifreeze can be added to component A to lower the freezing point of the slurry and ensure reaction activity. The amount of catalyst can be increased by 10% to 20% higher than at room temperature. The antifreeze can be ethylene glycol.

[0065] In addition, the amount of catalyst can be reduced in high-temperature environments (>30°C), or a cooling agent can be added to component A to absorb the exothermic reaction and prevent the slurry from gelling prematurely. The cooling agent can be a microcapsule-encapsulated phase change material.

[0066] It should be noted that when mixing components A and B, a silane coupling agent is used to treat the sodium silicate aqueous solution. The amino / epoxy groups of the coupling agent react with the polyurethane in component B through urea bond reaction. The siloxane groups in the silane coupling agent can combine with the SiO2 in the sodium silicate aqueous solution to form an organic-inorganic bridge, reducing phase separation.

[0067] Specifically, taking the amino-containing KH-550 silane coupling agent as an example, the siloxane group with the structure NH2(CH2)3Si(OCH3)3 reacts with SiO2 in sodium silicate to form an inorganic-inorganic link. The siloxane group undergoes hydrolysis in aqueous solution to generate active silanol groups. The aqueous solution of sodium silicate contains SiO2 monomers or oligomeric siloxane chains (containing Si-OH groups). The Si-OH generated by silane hydrolysis undergoes a dehydration condensation reaction with the Si-OH on the surface of SiO2 to form a stable Si-O-Si covalent bond. Finally, the silane coupling agent is anchored in the inorganic network of sodium silicate through the Si-O-Si bond, with the amino group (-NH2) exposed at the other end, preparing for reaction with the organic phase.

[0068] Polyurethane (component B) typically contains isocyanate groups (-NCO). The amino group (-NH2) or epoxy group (such as the epoxypropoxy group in KH-560) of the silane coupling agent reacts chemically with the -NCO to form an organic-organic bond. The amino group reacts with the urea bond of the -NCO (taking aminosilane as an example). The amino group (-NH2) of the silane is nucleophilic and undergoes an addition reaction with the -NCO in the polyurethane to form a urea bond. The epoxy group reacts with the -NCO (taking epoxysilane such as KH-560 as an example). Taking 60 as an example, the epoxy group undergoes ring opening under the action of a catalyst (such as amines) and undergoes an addition reaction with -NCO to form a urethane bond. Through the above two-step reaction, one end of the silane coupling agent is connected to the inorganic phase (SiO2 network) of sodium silicate through Si-O-Si bonds, and the other end is connected to the organic phase (-NCO chain) of polyurethane through urea bonds or urethane bonds, ultimately forming an organic-inorganic bridging structure of "inorganic phase-Si-O-Si-silane-urea bond / ester bond-organic phase".

[0069] Furthermore, the core of this process is the "bifunctional division of labor" of the silane coupling agent: the siloxane alkyl group (inorganic end) combines with the SiO2 of sodium silicate through hydrolysis-condensation reaction to form an inorganic link, and the amino / epoxy group (organic end) reacts with the -NCO of polyurethane to form an organic link. Finally, the silane molecules "bridge" the originally incompatible inorganic phase (sodium silicate) and organic phase (polyurethane), significantly improving the interfacial bonding force.

[0070] In addition, nano-SiO2 and nano-TiO2 can be added to component A, with a mass fraction of 1% to 3%. The nanoparticles can fill the interfacial gap between the sodium silicate aqueous solution and polyurethane, enhancing the interfacial bonding force. At the same time, the high specific surface area of ​​the nanoparticles can adsorb surfactants, further improving dispersibility and avoiding uneven solidified structure.

[0071] It should be noted that when mixing component A and component B, or when treating sodium silicate aqueous solution with fluorosilane, a hydrophobic layer is formed on the SiO2 surface through modification treatment, reducing the penetration of water and acid.

[0072] Furthermore, glass fiber or basalt fiber is added to component A. Sodium silicate forms a continuous Si-O-Si three-dimensional gel matrix through hydrolysis and condensation under the action of a catalyst. The surfactant ensures that the fiber is uniformly dispersed and bonded to the matrix. The glass fiber / basalt fiber is embedded in the matrix through physical interweaving and chemical adsorption, together forming a stable and high-strength three-dimensional structure that blocks the contact between the acid solution and the sodium silicate aqueous solution, while enhancing the crack resistance of the solidified body.

[0073] Mechanical property experiments of the grouting material: A grouting material consolidation body was prepared, and cores were taken using a vertical coring machine. The cores were processed into standard specimens with a diameter of 50 mm and a height of 100 mm. Uniaxial loading tests were conducted on intact specimens and grouting consolidation bodies of fractured rock blocks. The failure load and compressive strength of the specimens were measured, and the strength recovery coefficient (k-value) of the grouting consolidation body was calculated. Triaxial compressive strength tests were conducted on the specimens under lateral pressure to analyze the failure load and compressive strength of the grouting material consolidation body under different lateral pressures. Uniaxial shear loading tests were conducted on the specimens to measure their shear strength, evaluating the effect of grouting reinforcement on improving the shear resistance of the rock mass. The mechanical property data of different specimens were compared to analyze the degree to which grouting improves the residual strength of fractured rock or coal.

[0074] Water resistance test: Accurately weigh the grouting material and add an appropriate amount of water according to the recommended ratio. Stir evenly to form a slurry. Slowly pour the slurry into a standard graduated cylinder (e.g., a 1000mL graduated cylinder) until it reaches approximately 800mL ± 10mL. Cover with a sealed cap and let stand for 1 minute. Measure and record the initial slurry surface height (a1). Place the graduated cylinder on a horizontal operating table and maintain the ambient temperature and humidity as specified (e.g., temperature 20±1℃, relative humidity greater than 90%). After standing for 3 hours and 24 hours, measure and record the water level height (a2) and the slurry expansion surface height (a3). Calculate the bleeding rate and expansion rate according to the formulas.

[0075] Free water secretion rate: Bfi = (a2−a3)a1×100% Bfi = a1(a2−a3)×100%;

[0076] Free expansion rate: Bfi = (a3−a1)a1×100% Bfi = a1(a3−a1)×100%;

[0077] The arithmetic mean of the two parallel experimental data is taken as the final result.

[0078] Shrinkage rate experiment: Accurately weigh the grouting material and add an appropriate amount of water according to the recommended ratio, stir evenly to form a slurry, pour the slurry into a standard mold, smooth the surface, and gently vibrate if necessary to remove air bubbles. Let the molded specimen stand under standard conditions, such as 2 hours, to ensure the initial solidification of the slurry. Record the initial length or volume of the specimen as the benchmark for shrinkage rate calculation. Transfer the specimen to a curing chamber or a specific expansion measuring device, maintain constant temperature and humidity conditions, and use appropriate measuring tools, such as dial gauges or non-contact measuring systems, to monitor the volume change of the specimen at specific time points (such as 3 hours and 24 hours). Calculate the shrinkage rate based on the measured changes in specimen length or volume. The shrinkage rate calculation formula is usually: S=[(B−A) / B]×100%, where S is the shrinkage rate, B is the length before treatment, and A is the length after treatment. Analyze the shrinkage rate data to evaluate the volume change of the grouting material during the hardening process.

[0079] Example 2

[0080] The selected raw materials include component A and component B, wherein: component A contains polyether polyol, catalyst and surfactant;

[0081] Component B includes diphenylmethane diisocyanate and chain extender;

[0082] Component B reacts with component A to prepare a prepolymer. The prepolymer reacts with water in the environment to produce a solid that is insoluble in water and has a certain elasticity and strength. The polyether polyol in component A acts as a solidifying agent. The -NCO group contained in diphenylmethane diisocyanate reacts with -OH / water to generate polyurethane chains.

[0083] Example 3

[0084] The selected raw materials include component A and component B, wherein: component A includes epoxy resin, catalyst and surfactant;

[0085] Component B includes diphenylmethane diisocyanate and amine / anhydride curing agents;

[0086] Component B reacts with component A to prepare a prepolymer. The prepolymer reacts with water in the environment to produce a solid that is insoluble in water and has a certain elasticity and strength. The epoxy groups of the epoxy resin undergo ring-opening polymerization with the active groups of the curing agent (such as NH2) to form a dense, rigid cross-linked structure.

[0087] Comparative Example 1

[0088] Existing grouting reinforcement materials for fractured water-bearing surrounding rock generally include cement-based materials, resin and curing agent, flexible components, self-expanding components, fly ash, bentonite, ultrafine powder aggregate, and water-reducing agent. The difference from Example 1 is that the raw material components of this comparative example do not contain sodium silicate aqueous solution and polymeric MDI / TDI prepolymer. The rest of the preparation methods are the same as in Example 1.

[0089] Comparative Example 2

[0090] Hollow glass microspheres and powdered graphene oxide are further added to the existing grouting reinforcement material for fractured water-bearing surrounding rock. The difference from Example 1 is that the raw material components of this comparative example do not contain sodium silicate aqueous solution and polymeric MDI / TDI prepolymer, but hollow glass microspheres and powdered graphene oxide are added. The rest of the preparation method is the same as in Example 1.

[0091] Comparison Dimensions Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 core components Component A (sodium silicate aqueous solution, catalyst) + Component B (polymeric MDI / TDI prepolymer, plasticizer) Component A (polyether polyol, catalyst) + Component B (MDI / TDI, chain extender) Component A (epoxy resin) + Component B (amine / anhydride curing agent) The composition consists of: a base cementitious phase (cement-based materials, resin, and curing agent) + a functional conditioning phase (flexible components, self-expanding components, etc.) + an additive phase (water-reducing agent). Basic cementitious phase + functional modified phase + high-performance components (hollow glass microspheres, powdered graphene oxide) + auxiliary phase Solidification core mechanism 1. -NCO reacts with -OH / water to form polyurethane chains; 2. Sodium silicate aqueous solution dehydrates and condenses into a siliceous solid (filling the gaps in the polyurethane). -NCO reacts with -OH / water to form polyurethane chains (organic crosslinking only, no inorganic filler). <![CDATA[The epoxy groups of epoxy resin undergo ring-opening polymerization with the active groups of the curing agent (such as -NH2) to form a dense and rigid cross-linked structure]]> <![CDATA[The hydration reaction of cement generates products such as C-S-H gel and Ca(OH)2. At the same time, the Ca(OH)2 in fly ash undergoes "secondary hydration" to achieve "cementing aggregates + blocking waterways".]]> Based on Comparative Example 1, graphene oxide fills the micropores of cement hydration products through a bridging effect. Mechanical properties of solidified bodies Medium elasticity: tensile modulus 100-500MPa; medium strength: compressive strength 10-30MPa; balance between elasticity and rigidity. High elasticity: tensile modulus 50-200MPa; low strength: compressive strength 5-15MPa. Elasticity is preferred, strength is relatively weak. High rigidity: tensile modulus 1000-3000MPa; high strength: compressive strength 50-100MPa. Rigidity is preferred, but brittleness is high. Medium elasticity: tensile modulus 100-500 MPa; low strength: compressive strength 5-20 MPa; low toughness, high brittleness. Medium elasticity: tensile modulus 100-500 MPa; medium strength: compressive strength 12-28 MPa; low toughness, high brittleness. Water resistance Excellent water insolubility and non-dilutation, actively consuming environmental water. A well-consolidated solid is insoluble in water, but it easily swells when exposed to water, and its strength decreases with prolonged immersion in water. Poorly cured products have micropores, allowing water to easily penetrate and cause interfacial peeling; they also have poor resistance to damp heat. <![CDATA[Good bentonite forms a water - proof layer after swelling, but long - term immersion may lead to a strength reduction due to the dissolution of Ca(OH)₂]]> The excellent sheet-like structure of graphene oxide can form a physical barrier layer, reducing the channels for water molecule permeation. Flame retardancy Excellent sodium silicate aqueous solution has inherent flame retardant properties, inhibiting the combustion of polyurethane. Flammable pure polyurethane is an organic polymer that releases toxic gases when burned, requiring the addition of flame retardants. Pure resin is generally flammable and requires the addition of flame retardants to achieve flame retardancy, which increases costs. High-quality cement, fly ash, and bentonite are all inorganic materials that are non-flammable and produce no toxic fumes. High-quality cement, fly ash, and bentonite are all inorganic, non-combustible materials, and hollow glass microspheres are resistant to high temperatures. cost Sodium silicate aqueous solution can replace some of the high-priced polyurethane raw materials High dependence on pure MDI / TDI and polyether, resulting in high raw material costs. High-performance epoxy resins and specialized curing agents are expensive, especially high-performance models. Low-cement, fly ash, and bentonite are all inexpensive industrial raw materials. High cost of raw materials for medium and low-temperature hollow glass Shrinkage Sodium silicate aqueous solution coagulates without shrinkage; the slight expansion of polyurethane offsets the shrinkage. In the later stages of the reaction, the polyurethane chains shrink, which can easily create tiny gaps. Low-curing processes offer volume stability, but are highly brittle and prone to cracking due to shrinkage stress. Volume shrinkage occurs during the hydration process of cement. Low-oxidation graphene can inhibit shrinkage caused by microcracks.

[0092] Compared to ordinary roof grouting materials, sodium silicate aqueous solution-polyurethane grout is a prepolymer prepared by the polymerization reaction of polyisocyanate and polyhydroxy compound. It can react with sodium silicate aqueous solution and water in the environment to produce a solid that is insoluble in water and has a certain elasticity and strength. After the sodium silicate aqueous solution loses water, it solidifies into a high-strength solid, which fills the spaces between the long chains of polyurethane and plays a role in solidification. Sodium silicate aqueous solution polyurethane grout has a low cost, is inherently flame retardant, and can achieve good reinforcement effect in most cases.

[0093] Furthermore, in flowing water, sodium silicate aqueous solution polyurethane grout will not be diluted or dissolved, and its solidified body has high strength. Therefore, it can still play a good reinforcing role in the presence of water. The -NCO group contained in MDI or TDI can not only react with the -OH group of polyether polyol in component A and water, but also can self-polymerize.

[0094] Example 4

[0095] like Figure 1-2 As shown, the construction process of a grouting reinforcement material for fractured water-bearing surrounding rock adopts the borehole grouting method, and the specific steps are as follows:

[0096] S1. Drilling: The initial grouting depth is set at 15 to 20m. All holes will be vertical with an opening diameter of 130mm. When drilling into bedrock, the hole diameter can be appropriately reduced, but not less than 91mm. Drill to a depth of 0.5m into bedrock and use casing for wall protection. If a karst cave is encountered at the predetermined depth, drilling should continue to 1.0m below the bottom of the karst cave.

[0097] S2. Slurry preparation: A combination of static mixer and dynamic stirring is adopted. A static mixer is installed at the front end of the grouting pipe to ensure that components A and B are fully mixed during transportation. The storage tanks of components A and B are equipped with low-speed stirring devices to avoid sedimentation of sodium silicate aqueous solution and stratification of prepolymer.

[0098] S3. Grouting pressure: Generally, it should be no less than 0.1 to 0.3 MPa in bedrock, gradually increasing to 0.3 to 0.5 MPa at the rock-soil interface, with a maximum of 1.0 MPa. During construction, the grouting pressure should be adjusted according to the grouting situation, and the grouting pump flow rate should be 38 to 90 L / min.

[0099] S4. Grouting Completion Criteria: Grouting can be terminated when one of the following criteria is met:

[0100] ①The pressure at the grouting pipe orifice rises to above 0.5MPa and remains stable for 15 minutes;

[0101] ②The pressure at the grouting pipe orifice did not reach 0.5MPa, but the grouting rate was less than 5L / min and lasted for 15 minutes;

[0102] ③ The bedrock of the grouting borehole is intact, or multiple grouting operations are performed, and the borehole pressure exceeds 1.0 MPa;

[0103] ④ The grout leakage point has extended 3 to 5 meters beyond the grouting range;

[0104] ⑤ When the grouting volume in a single hole reaches 1.5 to 2.0 times the average grouting volume, and the grout absorption volume decreases significantly;

[0105] If the above standards are not met, the hole should be cleaned and grouting should be repeated.

[0106] S5. Grout diffusion radius: Grout diffusion radius is an important parameter in grouting treatment. However, due to the extremely uneven development of karst in both vertical and horizontal directions, it is difficult to obtain a representative grout diffusion radius applicable to the entire stratum, whether through theoretical calculation or grouting test. Based on the experience of grouting treatment projects, the diffusion radius in bedrock can be considered as 3.5m, and the diffusion radius in Quaternary can be considered as 0.75m.

[0107] In the specific implementation process, the application of borehole grouting has yielded significant results and the measures have been effective. However, it is important to pay special attention to the control of the borehole grouting process during construction to prevent errors from affecting the quality of the project. In the final construction quality inspection, two methods were used: core sampling of grouting holes and cross-hole electromagnetic wave CT detection of core drilling. The results were ideal, the images were intuitive, and the expected purpose was achieved. After the fully mechanized longwall face is mined, the filling pipeline is sent into the goaf through the drilling rig at a certain distance behind the working face. The A and B component materials are mixed to prepare slurry, which is then pumped to the adjacent face or the goaf of the same face for filling. This filling method can be divided into adjacent layer filling, same layer filling, and combined adjacent layer filling and same layer filling. It has the characteristics of simple process and minimal impact on filling and discharging procedures. It mainly fills the arc-shaped triangular areas on both sides of the goaf. When the pressure at the filling borehole increases to 2MPa or the grouting pump exceeds the rated working pressure, grouting is stopped. The material has a certain expansion rate. It can not only penetrate by relying on the concentration pressure difference of the pump pressure, but also by relying on the expansion of the material itself for secondary penetration. It can be injected into loose strata and bond firmly with various particles. It has better contact with the bonding surface, making the diffusion range and filling density of the grout higher than other materials. After the material is cured, it is tough and can withstand a certain amount of deformation under pressure.

[0108] The contents not described in detail in this description are existing technologies known to those skilled in the art. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A grouting reinforcement material for fractured water-bearing surrounding rock, characterized in that, The reinforcement material consists of component A and component B, wherein: Component A contains an aqueous solution of sodium silicate, a catalyst, and a surfactant; Component B is a polyisocyanate prepolymer, specifically composed of prepolymerized diphenylmethane diisocyanate and polyether polyol, with the addition of a plasticizer. The polymerization reaction of component B and component A prepares a prepolymer. The prepolymer reacts with water in the environment to produce a solid that is insoluble in water and has a certain elasticity and strength. After the sodium silicate aqueous solution in component A loses water, it solidifies into a high-strength solid and fills the spaces between the long polyurethane chains. The NCO group contained in the polymerized diphenylmethane diisocyanate can not only react with the OH group of the polyether polyol and water, but also can self-polymerize. The reaction mechanism is as follows: 1-1. Reaction of isocyanate and hydroxyl group: RN=C=O+R'-OH→RNHCOOR; 1-2. Reaction of isocyanate with water: 2R-N=C=O+H2O→RNHCONHR+CO2↑; 1-3. Urea carbamate reaction: RN=C=O + R'NHCOOR” → RNHCOR'NCOOR”; 1-4. Biuret reaction: RN=C=O+R'NHCONHR'→RNHCOR'NCONHR.

2. The grouting reinforcement material for fractured water-bearing surrounding rock according to claim 1, characterized in that: The concentration of the sodium silicate aqueous solution in component A is controlled, and the mass fraction of the sodium silicate aqueous solution is limited to 30% to 40% to avoid excessive water triggering a large number of reactions 1-2. A desiccant is added to component A to adsorb free water in the environment and reduce the side reaction between NCO and water. The desiccant can be anhydrous calcium chloride.

3. The grouting reinforcement material for fractured water-bearing surrounding rock according to claim 1, characterized in that: The structure of the prepolymer of component B is adjusted by prepolymerizing it with a high-functionality polyether polyol and a polyisocyanate prepolymer, increasing the competitive priority of -NCO and -OH in reaction 1-1, reducing the proportion of reaction 1-2, and reducing the amount of CO2 generated from the source. The high-functionality polyether polyol can be selected as a 4-functionality polyether.

4. The grouting reinforcement material for fractured water-bearing surrounding rock according to claim 1, characterized in that: Add an organosilicon defoamer to component A to inhibit the formation and growth of CO2 bubbles in reaction 1-2. The organosilicon defoamer can be selected as polydimethylsiloxane.

5. The grouting reinforcement material for fractured water-bearing surrounding rock according to claim 1, characterized in that: The catalyst in component A is a combination of a main catalyst and a retarder. The main catalyst ensures the final reaction is complete, and the main catalyst can be selected as dibutyltin dilaurate; The delay agent inhibits the reaction in the early stage of grouting, ensuring that the grout has sufficient flow time. After penetrating into the micro-cracks, the delay agent gradually becomes ineffective, and the reaction accelerates solidification. The delay agent can be selected as benzoyl chloride or phosphate ester.

6. The grouting reinforcement material for fractured water-bearing surrounding rock according to claim 5, characterized in that: In low-temperature environments (<5℃), the amount of catalyst can be increased, or an antifreeze can be added to component A to lower the freezing point of the slurry and ensure reaction activity. The amount of catalyst can be increased by 10% to 20% higher than at room temperature. The antifreeze can be ethylene glycol. Reduce the amount of catalyst used in high-temperature environments (>30℃), or add a cooling agent to component A to absorb the exothermic reaction and prevent the slurry from gelling prematurely. The cooling agent can be a microcapsule-encapsulated phase change material.

7. The grouting reinforcement material for fractured water-bearing surrounding rock according to claim 1, characterized in that: When mixing components A and B, a sodium silicate aqueous solution is treated with a silane coupling agent. The amino / epoxy groups of the coupling agent react with the polyurethane in component B through urea bond reactions. The siloxane groups in the silane coupling agent can combine with the SiO2 in the sodium silicate aqueous solution to form an organic-inorganic bridge, reducing phase separation.

8. The grouting reinforcement material for fractured water-bearing surrounding rock according to claim 7, characterized in that: Nano-SiO2 and nano-TiO2 can be added to component A, with a mass fraction of 1% to 3%. The nanoparticles can fill the interfacial gap between the sodium silicate aqueous solution and polyurethane, enhancing the interfacial bonding force. At the same time, the high specific surface area of ​​the nanoparticles can adsorb surfactants.

9. The grouting reinforcement material for fractured water-bearing surrounding rock according to claim 1, characterized in that: When mixing component A and component B, or by treating the sodium silicate aqueous solution with fluorosilane, a hydrophobic layer is formed on the SiO2 surface through modification treatment, reducing the penetration of water and acid. Glass fiber or basalt fiber is added to component A. Sodium silicate forms a continuous Si-O-Si three-dimensional gel matrix through hydrolysis and condensation under the action of a catalyst. Surfactant ensures that the fiber is uniformly dispersed and bonded to the matrix. Glass fiber / basalt fiber is embedded in the matrix through physical interweaving and chemical adsorption, together forming a stable and high-strength three-dimensional structure that blocks the contact between acid and sodium silicate aqueous solution, while enhancing the crack resistance of the solidified body.

10. A construction process for a grouting reinforcement material for fractured water-bearing surrounding rock, applicable to the grouting reinforcement material for fractured water-bearing surrounding rock as described in any one of claims 1-9, characterized in that: A construction process for a grouting reinforcement material for fractured, water-bearing surrounding rock employs the borehole grouting method, with the specific steps as follows: S1. Drilling: The initial grouting depth is set at 15 to 20m. All holes will be vertical with an opening diameter of 130mm. When drilling into bedrock, the hole diameter can be appropriately reduced, but not less than 91mm. Drill to a depth of 0.5m into bedrock and use casing for wall protection. If a karst cave is encountered at the predetermined depth, drilling should continue to 1.0m below the bottom of the karst cave. S2. Slurry preparation: A combination of static mixer and dynamic stirring is adopted. A static mixer is installed at the front end of the grouting pipe to ensure that components A and B are fully mixed during transportation. The storage tanks of components A and B are equipped with low-speed stirring devices to avoid sedimentation of sodium silicate aqueous solution and stratification of prepolymer. S3. Grouting pressure: Generally, it should be no less than 0.1 to 0.3 MPa in bedrock, gradually increasing to 0.3 to 0.5 MPa at the rock-soil interface, with a maximum of 1.0 MPa. During construction, the grouting pressure should be adjusted according to the grouting situation, and the grouting pump flow rate should be 38 to 90 L / min. S4. Grouting Completion Criteria: Grouting can be terminated when one of the following criteria is met: ①The pressure at the grouting pipe orifice rises to above 0.5MPa and remains stable for 15 minutes; ②The pressure at the grouting pipe orifice did not reach 0.5MPa, but the grouting rate was less than 5L / min and lasted for 15 minutes; ③ The bedrock of the grouting borehole is intact, or multiple grouting operations are performed, and the borehole pressure exceeds 1.0 MPa; ④ The grout leakage point has extended 3 to 5 meters beyond the grouting range; ⑤ When the grouting volume in a single hole reaches 1.5 to 2.0 times the average grouting volume, and the grout absorption volume decreases significantly; If the above standards are not met, the hole should be cleaned and grouting should be repeated. S5. Grout diffusion radius: Grout diffusion radius is an important parameter in grouting treatment. However, due to the extremely uneven development of karst in both vertical and horizontal directions, it is difficult to obtain a representative grout diffusion radius applicable to the entire stratum, whether through theoretical calculation or grouting test. Based on the experience of grouting treatment projects, the diffusion radius in bedrock can be considered as 3.5m, and the diffusion radius in Quaternary can be considered as 0.75m.

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