Water-rich sand layer pipe jacking construction resistance reducing and seepage preventing agent and preparation method thereof

Abstract

The application discloses a water-rich sand layer pipe jacking construction resistance-reducing and anti-seepage agent and a preparation method thereof. The resistance-reducing and anti-seepage agent comprises an anti-seepage slurry and a resistance-reducing slurry. The anti-seepage slurry raw materials comprise 30-40 parts of polyurethane components, 2-5 parts of epoxy resin and 5-15 parts of inorganic materials. The resistance-reducing slurry raw materials comprise 10-15 parts of graphite, 10-15 parts of soda ash and 2-5 parts of polyacrylamide. The anti-seepage slurry raw materials and the resistance-reducing slurry raw materials are dispersed in water respectively to obtain an anti-seepage slurry with a mass concentration of 30-50% and a resistance-reducing slurry with a mass concentration of 5-20%. The anti-seepage slurry and the resistance-reducing slurry are uniformly mixed in a mass ratio of (1-99):(99-1) to obtain the resistance-reducing and anti-seepage agent. The resistance-reducing and anti-seepage agent has high water retention, anti-seepage, stability and controllable thixotropy, can adapt to the requirements of complex strata in a long-distance pipe jacking construction process, and can effectively control seepage and reduce pipe wall friction resistance in a water-rich sand layer environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of drag reduction and anti-seepage agents and construction technology, and particularly relates to a drag reduction and anti-seepage agent for water-rich sand layer pipe jacking construction, a preparation method thereof and a pipe jacking system construction method. BACKGROUND

[0002] With the development of urbanization in China, the urban land in the Yangtze River Delta region is becoming increasingly scarce, and a large number of urban power infrastructure needs to be buried, and the pipe jacking method is a construction method widely used in urban cable tunnels. As one of the main methods of trenchless technology, the pipe jacking method is increasingly used. In the past, the pipe jacking method was mostly used to build urban underground pipe galleries or small-diameter and short-distance trench engineering, but now the pipe jacking method is increasingly used to build tunnels in subway tunnels, station auxiliary structures and other functional municipal engineering. The use of the pipe jacking method to build tunnels in bustling urban areas can ensure smooth ground traffic during construction, reduce construction land, and avoid various problems caused by demolition.

[0003] However, water-rich sand layer is a special complex stratum in the Yangtze River Delta region, and urban power pipe jacking construction faces many problems such as anti-seepage control when crossing the water-rich sand layer. In long-distance pipe jacking construction, the pipe wall friction resistance is too large, and the traditional drag reduction agent does not have anti-seepage function. The pipe wall extrusion friction in the water-rich sand layer causes local excess pore water pressure, which can cause serious leakage problems at the pipe joint, the interface between the pipe joint and the working well, and the equipment wall hole.

[0004] In the existing pipe jacking construction, in order to reduce the friction between the overlying soil and the pipe joint, mud slurry material is injected into the gap outside the pipe joint through the grouting hole inside the pipe joint. First, it plays a lubricating role. During the jacking construction process, the mud slurry is disturbed by pumping, flowing and other external disturbances, and the slurry lubricates the friction between the pipe joint structure and the soil in the form of a flow state, thereby reducing the jacking resistance. Second, it plays a filling and supporting role. After the slurry is static, it becomes a gel, which can effectively fill and support the gap between the pipe joint structure and the surrounding soil, reduce stratum disturbance and settlement deformation, and ensure the safety and controllability of the surrounding environment. At present, in the preparation process of the drag reduction mud slurry, most cases still rely on traditional empirical rules to determine, and the accuracy of the material cannot be ensured every time the mud slurry is mixed, which often leads to unstable performance of the prepared mud slurry. This phenomenon has a significant impact on construction application. Therefore, it is very important to study the proportioning and construction method of the grouting material in the pipe jacking construction process.

[0005] Invention CN 112851216A discloses a high water retention low viscosity pipe jacking thixotropic mud, which contains the following components and the mass fraction of each component: sodium bentonite 4-8 parts, soda ash 0.2-0.3 parts, fly ash microbeads 1-4 parts, warm wheel glue 0.05-0.2 parts, and water 85.5-94.75 parts. The invention has high water retention at a lower dosage of bentonite and external agent, and is suitable for complex strata such as groundwater-rich strata and sandy soil. The design of the thixotropic mud pursues high water retention and low viscosity to adapt to complex strata. However, in long-distance pipe jacking construction, low viscosity can cause the slurry to flow too fast, making it difficult to form a stable slurry layer in the pipe, and then causing loss or accumulation in some parts. This uneven flow makes it difficult for the mud to be evenly distributed.

[0006] Invention CN107858150A discloses a thixotropic mud, which is prepared by sequentially weighing 30-40 parts of bentonite, 6-8 parts of soda ash, 1-2 parts of sodium hydroxymethyl cellulose, 3-5 parts of polyacrylamide, 5-6 parts of modified graphite, 4-6 parts of modified water-retaining gel, 2-3 parts of retarder, 3-6 parts of polyethylene oxide, and 60-70 parts of water. Although the thixotropic mud improves the water retention and permeability resistance of the mud by adding polyacrylamide, the main component of the mud is bentonite, which has a large natural difference in composition and makes it difficult to accurately control the effective component ratio in the thixotropic mud.

[0007] Therefore, how to provide a high-adaptability drag-reducing and anti-seepage mud with high water retention, permeability resistance and controllable thixotropy to meet the needs of complex strata in long-distance pipe jacking construction, especially to effectively control seepage in water-rich sand layer environment, reduce pipe wall friction resistance, and maintain the performance stability of the mud during transportation and standing, has become a problem to be solved by those skilled in the art. SUMMARY

[0008] In view of the defects in the prior art, the present application provides a water-rich sand layer pipe jacking construction drag-reducing and anti-seepage agent, a preparation method thereof and a pipe jacking system construction method. The drag-reducing and anti-seepage agent is designed to be obtained by properly proportioning an anti-seepage slurry and a drag-reducing slurry, has the advantages of high water retention, permeability resistance, controllable thixotropy, performance stability and high adaptability, and can meet the needs of complex strata in long-distance pipe jacking construction, especially effectively control seepage in water-rich sand layer environment and reduce pipe wall friction resistance.

[0009] In the first aspect, the present application provides a water-rich sand layer pipe jacking construction drag-reducing and anti-seepage agent, which comprises an anti-seepage slurry and a drag-reducing slurry.

[0010] The raw materials of the anti-seepage slurry include, by mass fraction:

[0011] Polyurethane component 30-40 parts

[0012] 2-5 parts epoxy resin

[0013] 5-15 parts of inorganic materials;

[0014] The raw materials for drag-reducing slurry include:

[0015] 10-15 parts graphite

[0016] 10-15 parts of soda ash

[0017] 2-5 parts of polyacrylamide;

[0018] The raw materials of the impermeable grout are dispersed in water to obtain an impermeable grout with a mass concentration of 30-50%.

[0019] The raw materials for the drag-reducing slurry are dispersed in water to obtain a drag-reducing slurry with a mass concentration of 5-20%.

[0020] The impermeable grout and the drag-reducing grout are mixed evenly at a mass ratio of (1-99):(99-1) to obtain the drag-reducing and impermeable agent.

[0021] Existing technologies often use bentonite as the main material for thixotropic drilling mud. Bentonite possesses good water absorption, swelling properties, and a certain degree of thixotropy, enabling it to form a high-viscosity structure when stationary, preventing mud loss and providing support and lubrication. However, due to the significant natural variations in bentonite composition, precise control is difficult. Furthermore, the thixotropic properties it forms in the mud are relatively limited, with limited shear-thinning ability, making it difficult to adapt to various rheological requirements under different working conditions.

[0022] This invention utilizes a combination of organic and inorganic components to obtain a highly adaptable drag-reducing and seepage-proofing agent. In the seepage-proofing grout, waterborne polyurethane components, epoxy resin, and inorganic materials form a dense network structure within the grout system, significantly enhancing the grout's impermeability and water-blocking properties, making it particularly suitable for high-permeability formations such as water-rich sand layers. Furthermore, the grout's fluidity and viscosity can be more precisely controlled through the proportions of waterborne polyurethane components, epoxy resin, and inorganic materials, avoiding the risks of loss of effective components due to excessively low viscosity or pipe blockage due to excessively high viscosity. In the drag-reducing grout, graphite provides lubrication and filling, soda ash maintains the overall dispersion of the drag-reducing grout and adjusts the pH value, and polyacrylamide thickens and provides thixotropy. This combination ensures both the fluidity of the drag-reducing grout during transportation and its lubrication and support at the pipe wall, effectively reducing frictional resistance during long-distance pipe jacking construction.

[0023] Preferably, the polyurethane component comprises the following raw materials in parts by weight:

[0024] 50-100 parts of isocyanate

[0025] 10-50 parts of polyol

[0026] 1-5 parts of terminal hydroxyl compound,

[0027] In this process, polyols and hydroxyl-terminated compounds are first mixed evenly, and then isocyanates and optional additives are added to prepare an aqueous polyurethane component containing polyurethane prepolymer.

[0028] Isocyanates include one or more of the following: phenyl diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), polymethylene polyphenyl polyisocyanate (PAPI), and diphenylmethane diisocyanate (MDI).

[0029] Polyols include at least one of polyester polyols, polyether polyols, oligomeric polyols containing unsaturated bonds, and glycerol;

[0030] Hydroxyl-terminated compounds include hydroxyl-terminated polyethylene oxide polymers, polyoxyethylene-polyoxypropylene monohydric alcohols, or mixtures thereof;

[0031] The additives include one or more of catalysts, curing agents, stabilizers, and coupling agents, and the total amount of additives accounts for about 2-10% of the mass of isocyanate;

[0032] Among them, the catalyst is preferably DBTDL, the curing agent is preferably DMP-30, the foam stabilizer is preferably AK8805, and the coupling agent can be a silane coupling agent, preferably KH560.

[0033] Preferably, the epoxy resin comprises porous epoxy resin particles with an average particle size of 30-100 μm and an average pore size of 10 to 2000 nm.

[0034] The inorganic material includes one or more of cement, controllable clay, and water glass;

[0035] The porous epoxy resin particles and / or inorganic materials are pretreated with a silane coupling agent containing isocyanate reactive groups.

[0036] The silane coupling agent used for the pretreatment, such as the silane coupling agent represented by formula AR-Si-(B)3, wherein A can be an isocyanate reactive group selected from at least one of amino, hydroxyl, or mercapto groups, B can be an alkoxy group, and R is selected from aromatic or aliphatic ester groups. When preparing the geomembrane grout, after mixing the porous epoxy resin particles and / or inorganic materials pretreated with this silane coupling agent with an aqueous polyurethane component containing polyurethane prepolymer, due to the excess isocyanate in the aqueous polyurethane component, the reactive group can react with the aqueous polyurethane component to form a hydrophilic core-shell structure in which the epoxy particles and / or inorganic particles are coated with aqueous polyurethane, thereby improving the hydrophilic stability of the geomembrane grout.

[0037] Preferably, the polyacrylamide includes one or more of cationic polyacrylamide, anionic polyacrylamide, and nonionic polyacrylamide;

[0038] Graphite is obtained by combining micro-nano graphite powder with a particle size of 1-10 μm and expanded graphite with a particle size of 20-50 μm, with the mass ratio of micro-nano graphite powder to expanded graphite being (10-20):(1-5).

[0039] The long-chain structure and polar groups (amide groups) of polyacrylamide enable it to thicken, retain water, resist seepage, and regulate rheology in drag-reducing grouts. Through physical entanglement and chemical adsorption, it forms an elastic and resilient gel network within the drag-reducing grout system. This network can adapt to changes in external forces under different construction conditions, thereby improving the stability, lubricity, and support effect of the drag-reducing grout. This invention, by adding polyacrylamide and graphite to the drag-reducing grout, enhances both the thixotropy and viscosity of the drag-reducing agent, further improving its lubrication effect.

[0040] Furthermore, combining graphite with different particle sizes and morphologies can better enhance its supporting and lubricating effects. Expanded graphite (EG), a novel functional carbon material, is a loose, porous, worm-like substance obtained from natural graphite through intercalation, washing, drying, and high-temperature expansion. In addition to possessing the excellent properties of natural graphite, such as resistance to cold and heat, corrosion resistance, and self-lubrication, expanded graphite also exhibits superior flexibility, compression resilience, adsorption capacity, environmental compatibility, biocompatibility, and radiation resistance.

[0041] Preferably, the polyacrylamide and expanded graphite are pre-formed into an intercalated composite structure, comprising the following steps:

[0042] S1-1. Expanded graphite is ultrasonically dispersed in an ethanol-water solution to obtain a graphite dispersion.

[0043] S1-2. Polyacrylamide is added to graphite dispersion, stirred and ultrasonically treated to obtain polyacrylamide-graphite intercalation composite structure.

[0044] To better leverage the advantages of expanded graphite, an ultrasonic-assisted pretreatment process was used to create a multi-layered intercalation composite structure in which polymers are inserted into expanded graphite. This resulted in a more stable and uniform dispersion of expanded graphite within the polymer matrix. Compared to the intercalation structure of natural graphite, expanded graphite, with its larger and more diverse layered structure, allows for more effective insertion into polymer macromolecules under relatively mild conditions.

[0045] More preferably, polyacrylamide and expanded graphite are pre-formed into a composite gel, comprising the following steps:

[0046] S2-1. Disperse expanded graphite in water, add acrylamide monomer and ammonium persulfate (APS), and sonicate for 10-20 minutes.

[0047] S2-2, Add tetramethylethylenediamine (TEMED) and sonicate for 2-5 minutes;

[0048] S2-3. React at 40-60℃ for 2-24 hours to obtain aqueous polyacrylamide-graphite composite gel.

[0049] By mixing and polymerizing expanded graphite with acrylamide monomers and initiators, the polymer can penetrate deep into the expanded graphite to form a better filled intercalation structure. Furthermore, expanded graphite possesses a richer, more porous structure than ordinary natural graphite, providing a physical crosslinking method for polyacrylamide—topological crosslinking. In aqueous polyacrylamide-graphite composite gels using expanded graphite as crosslinking points, the polymerized monomers form molecular chains that pass through these pores during polymerization. These pores do not exert excessive "locking forces" on the molecular chains; the free sliding of the molecular chains generates a pulley-like effect, improving the drag-reduction performance of the slurry.

[0050] Secondly, the present invention also provides a method for preparing a drag-reducing and seepage-preventing agent for pipe jacking construction in water-rich sand layers as described above, comprising the following steps:

[0051] S1. Prepare the impermeable grout:

[0052] Weigh the raw materials for the anti-seepage grout according to the preset ratio;

[0053] The raw materials for the impermeable grout are dispersed in water and mixed evenly to form an impermeable grout with a mass concentration of 30-50%.

[0054] S2. Prepare drag-reducing slurry:

[0055] Weigh the raw materials for the drag-reducing slurry according to the preset proportions;

[0056] The raw materials for drag-reducing slurry are dispersed in water and mixed evenly to form a drag-reducing slurry with a mass concentration of 5-20%.

[0057] S3. Mix the impermeable grout and the drag-reducing grout at a mass ratio of (1-99):(99-1) to obtain the drag-reducing and impermeable agent.

[0058] Thirdly, the present invention also provides a construction method for a pipe jacking system utilizing the aforementioned drag-reducing and seepage-preventing agent for pipe jacking in water-rich sand layers. The pipe jacking system includes a head pipe section and several body pipe sections connected in sequence. The construction method includes the following steps:

[0059] Step 1: Based on the application location of the drag-reducing and seepage-proofing agent in the pipe jacking system, prepare the seepage-proofing compound agent and the drag-reducing compound agent respectively;

[0060] An anti-seepage compounding agent is used, wherein the anti-seepage grout and the drag-reducing grout are mixed at a mass ratio of (65-90):(10-35);

[0061] The drag-reducing compounding agent is used, wherein the impermeable grout and the drag-reducing grout are mixed at a mass ratio of (10-35):(65-90);

[0062] Step 2: Determine the laying path of the pipe jacking system segments and excavate the tunnel;

[0063] Step 3: Install the jacking device and the tunneling device in the tunnel, and use the jacking device to advance the tunneling device;

[0064] Step 4: Install the head pipe section in the tunnel, and apply the aforementioned anti-seepage compounding agent at the port of the head pipe section;

[0065] Step 5: Push in the fuselage tube sections one by one, connecting the ends of each fuselage tube section until all fuselage tube sections are installed. During this process, apply the drag-reducing compound between each fuselage tube section.

[0066] The tunnels excavated according to the pipe jacking system's segment laying path include, but are not limited to, launch pits and receiving pits. A jacking device is installed in the launch pit, and the tunneling equipment is hoisted into the launch pit to enable the jacking device to advance the tunneling equipment. Subsequent head and body pipe segments can be lowered into the launch pit using hoisting methods.

[0067] In pipe jacking system construction, the drag-reducing and seepage-proofing agent used in water-rich sandy layers can be flexibly adjusted in proportion to the seepage-proofing grout and drag-reducing grout according to the specific application location. This effectively enhances the seepage-proofness of the head pipe section and reduces the jacking resistance of the body pipe sections. Specifically, the proportion of drag-reducing grout can be appropriately increased in the pipe body section to improve lubrication performance and effectively reduce the frictional resistance between the pipe wall and the surrounding soil. This flexible adjustment ensures smooth pipe jacking during advancement, helping to reduce the workload of equipment, decrease construction costs, and extend the service life of construction equipment. In the head pipe section and in special geological areas, increasing the proportion of seepage-proofing grout can form a dense seepage-proof layer between pipe sections, effectively preventing water or mud leakage. This adjustment ensures the stability of pipe section interfaces, working shaft interfaces, and through-wall holes under high pressure and water-rich environments, preventing structural damage due to leakage and ensuring construction safety.

[0068] Flexible adjustment of the ratio of impermeable grout to drag-reducing grout helps to rationally use impermeable and drag-reducing materials in different locations and working conditions, avoiding material waste. By adding impermeable or drag-reducing components when needed, unnecessary material consumption can be reduced, which helps to lower construction costs and improve resource utilization efficiency.

[0069] Preferably, in step five, each body pipe section includes a spigot end and a socket end at both ends. The spigot end and socket end of adjacent body pipe sections are inserted and fitted to form an installation gap. A steel pipe sleeve and a sealing ring are set in the installation gap. The sealing ring is inflated and expands, creating a liquid injection gap between the pipe section wall and the steel pipe sleeve. The drag-reducing compound is applied to the liquid injection gap. Then, the inflated sealing ring is deflated and shrinks.

[0070] Preferably, the shrinkage outer diameter of the sealing ring after deflating or deflation is less than or equal to the outer diameter of the pipe section wall;

[0071] The compression amount of the sealing ring after inflation is less than or equal to half of the outer diameter of the sealing ring after inflation. Preferably, the contact pressure of the sealing ring is above 0.3 MPa.

[0072] Preferably, the sealing ring is an inflatable rubber sealing ring, which surrounds the socket end of the machine body pipe section; more preferably, the inflatable rubber sealing ring contains neoprene rubber with high sealing performance.

[0073] When adjacent fuselage pipe sections are connected, the spigot end of one fuselage pipe section is inserted into the socket end of another fuselage pipe section. The spigot end and the socket end are interlocked and connected to each other, forming the installation gap. The rubber sealing ring is fitted into the installation gap. After high-pressure gas is injected into the rubber sealing ring, its elastic deformation pushes up the steel pipe sleeve at the socket end, forming an effective support structure. This creates an injection gap between the pipe section wall and the steel pipe sleeve, facilitating the injection of drag-reducing and seepage-proofing agents into the gap. At the same time, after the rubber sealing ring is inflated, it seals the segmented gaps of the pipe section, helping to seal the injected drag-reducing and seepage-proofing agents and ensuring that the agents achieve the required effect at the corresponding locations.

[0074] During pipe jacking, the inflated rubber sealing ring seals the gap between the jacking pipe and the steel pipe sleeve, applying axial restraint to the spigot and preventing slippage due to internal pipe pressure or external forces. Before jacking, the high-pressure gas in the rubber ring is released, further reducing the gap between the ground and the pipe wall and decreasing frictional resistance. This controllable friction adjustment effectively reduces the workload on the equipment, extends its service life, and lowers construction costs.

[0075] The present invention has at least the following beneficial effects:

[0076] (1) The drag-reducing and seepage-proofing agent of this invention adopts a composite component of organic / inorganic materials, and a compounding method of seepage-proofing grout and drag-reducing grout, which enables the drag-reducing and seepage-proofing agent to have excellent seepage-proofing and drag-reducing properties in the construction of pipe jacking in water-rich sandy layers. The polyurethane component and epoxy resin in the seepage-proofing grout provide extremely high sealing and seepage-proof performance, forming a dense waterproof layer to resist the seepage pressure of water-rich strata; the inorganic materials further enhance the compressive strength, so that the grout remains stable under high pressure conditions. At the same time, the graphite and polyacrylamide in the drag-reducing grout interact, with graphite providing lubrication and reducing friction between the pipe and the soil, while polyacrylamide improves the water retention and thixotropy of the grout, ensuring that the grout forms a uniform drag-reducing layer around the pipe wall, thereby effectively reducing the propulsion resistance.

[0077] (2) Based on a compound graphite composition, this invention utilizes the porous worm-like structure of expanded graphite and the high water absorption and thixotropic properties of polyacrylamide to form a stable intercalated composite structure or composite gel. This not only provides excellent self-lubrication and compression resilience but also enhances the resilience, pressure resistance, and drag reduction effect of the composite material through a topological cross-linking structure that generates a "pulley-like effect." In long-distance pipe jacking construction, this composite material can flexibly adjust its drag reduction performance under different working conditions, achieving the dual effects of high viscosity support when stationary and good flow under shear force, providing more stable and efficient drag reduction and seepage prevention support for complex geological conditions.

[0078] (3) In the seepage-proof grout of the present invention, the porous epoxy resin particles and / or inorganic materials are pretreated by a silane coupling agent containing isocyanate reactive groups. This allows the grout to react and connect with the excess isocyanate in the waterborne polyurethane component containing polyurethane prepolymer. This not only improves the hydrophilic stability of the seepage-proof grout, but also enhances the adhesion strength between the grout and the substrate. This is beneficial for the drag-reducing seepage-proof agent provided by the present invention to quickly stop leakage and control seepage during the construction of pipe jacking in water-rich sand layers.

[0079] (4) The drag-reducing and seepage-proofing agent prepared by this invention can be flexibly proportioned according to the needs of different parts of the pipe jacking system. Increasing the proportion of seepage-proofing agent in the pipe head section enhances the seepage-proofing effect, while increasing the proportion of drag-reducing agent in the pipe body section reduces frictional resistance and improves the smoothness of pipe jacking and construction efficiency. This zoned application can effectively reduce construction costs while ensuring structural safety.

[0080] (5) The pipe jacking system disclosed in this invention adds rubber sealing rings between pipe sections, which can seal the gaps between pipe sections, making the coating range of the drag-reducing and seepage-proofing agent more comprehensive, ensuring that key parts and potential leakage points are uniformly covered without omission, thereby improving the overall sealing and seepage resistance. At the same time, the inflation function of the rubber rings can temporarily seal the gap between the jacking pipe and the formation during pipe jacking, reducing frictional resistance, significantly reducing the load on the equipment, and extending the service life of the equipment. Attached Figure Description

[0081] Figure 1 This is a schematic diagram of the pipe jacking system of the present invention;

[0082] Figure 2 This is an axial schematic diagram of the pipe joint connection structure of the pipe jacking system of the present invention;

[0083] Figure 3 This is a schematic diagram of the pipe jacking system construction method of the present invention.

[0084] Explanation of reference numerals in the attached diagram: 1-Injection gap, 2-Steel sleeve, 3-Sealing ring, 4-Socket end, 5-Spigot end. Detailed Implementation

[0085] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the specification and specific implementation methods. Obviously, the described embodiments are merely 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.

[0086] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0087] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0088] The following will be combined with the appendix Figures 1-3 The present invention further describes the drag-reducing and seepage-preventing agent, jacking system, and preparation method for water-rich sand layer pipe jacking construction.

[0089] A drag-reducing and seepage-preventing agent for pipe jacking construction in water-rich sandy layers, specifically comprising:

[0090] (1) Impermeable grout, by weight, includes:

[0091] 1.1) 30-40 parts of polyurethane component

[0092] 1.2) 2-5 parts epoxy resin

[0093] 1.3) 5-15 parts of inorganic materials;

[0094] Among them, 1.1) the polyurethane component includes the following raw material composition:

[0095] 50-100 parts of isocyanate

[0096] 10-50 parts of polyol

[0097] 1-5 parts of terminal hydroxyl compound;

[0098] First, the polyol and the hydroxyl-terminated compound are mixed evenly, and then the isocyanate (in excess) and optional additives are added to prepare an aqueous polyurethane component containing polyurethane prepolymer.

[0099] 1.2) Epoxy resin includes porous epoxy resin particles with an average particle size of 30-100 μm and an average pore size of 10 to 2,000 nm.

[0100] 1.3) Inorganic materials include one or more of cement, controllable clay, and water glass;

[0101] The porous epoxy resin particles and / or inorganic materials are pretreated with a silane coupling agent, which contains isocyanate reactive groups and can react and connect with excess isocyanate in the waterborne polyurethane component containing polyurethane prepolymer to form a hydrophilic core-shell structure in which the epoxy particles and / or inorganic particles are coated with waterborne polyurethane.

[0102] The raw materials of the impermeable grout are dispersed in water to obtain an impermeable grout with a mass concentration of 30-50%.

[0103] (2) Drag-reducing slurry, by mass parts, includes:

[0104] 2.1) 10-15 parts graphite

[0105] 2.2) 10-15 parts of soda ash

[0106] 2.3) Polyacrylamide 2-5 parts;

[0107] Among them, 2.1) graphite is made by combining micro-nano graphite powder with a particle size of 1-10μm and expanded graphite with a particle size of 20-50μm, with the mass ratio of micro-nano graphite powder to expanded graphite being (10-20):(1-5).

[0108] 2.2) Polyacrylamide includes one or more of cationic polyacrylamide, anionic polyacrylamide, and nonionic polyacrylamide;

[0109] Preferably, polyacrylamide and expanded graphite are pre-formed into an intercalated composite structure or a composite gel:

[0110] ① Intercalation composite structure, including the following preparation steps:

[0111] S1-1. Expanded graphite is ultrasonically dispersed in an ethanol-water solution to obtain a graphite dispersion.

[0112] S1-2. Polyacrylamide is added to graphite dispersion, stirred and ultrasonically treated to obtain polyacrylamide-graphite intercalation composite structure.

[0113] ②The composite gel comprises the following preparation steps:

[0114] S2-1. Disperse graphite in water, add acrylamide monomer and ammonium persulfate (APS), and sonicate for 10-20 minutes.

[0115] S2-2, Add tetramethylethylenediamine (TEMED) and sonicate for 2-5 minutes;

[0116] S2-3. React at 40-60℃ for 2-24 hours to obtain aqueous polyacrylamide-graphite composite gel.

[0117] The raw materials for the drag-reducing slurry are dispersed in water to obtain a drag-reducing slurry with a mass concentration of 5-20%.

[0118] The impermeable grout and the drag-reducing grout are mixed evenly at a mass ratio of (1-99):(99-1) to obtain a drag-reducing and impermeable agent. The drag-reducing and impermeable agent is used in a pipe jacking system. According to the location and requirements, the ratio of impermeable grout and drag-reducing grout in the drag-reducing and impermeable agent is adjusted to obtain an impermeable compounding agent and a drag-reducing compounding agent, respectively.

[0119] A construction method for a pipe jacking system utilizing the aforementioned drag-reducing and seepage-preventing agent for water-rich sand layers, wherein the pipe jacking system comprises a head pipe section and several body pipe sections connected in sequence, and the construction method includes the following steps:

[0120] Step 1: Based on the application location of the drag-reducing and seepage-proofing agent in the pipe jacking system, prepare the seepage-proofing compound agent and the drag-reducing compound agent respectively;

[0121] An anti-seepage compounding agent is used, wherein the anti-seepage grout and the drag-reducing grout are mixed at a mass ratio of (65-90):(10-35);

[0122] The drag-reducing compounding agent is used, wherein the impermeable grout and the drag-reducing grout are mixed at a mass ratio of (10-35):(65-90);

[0123] Step 2: Determine the laying path of the pipe sections in the pipe jacking system and excavate the launch pit and receiving pit;

[0124] Step 3: Install the jacking device in the launch pit, hoist the tunneling device into the launch pit, and advance the tunneling device through the jacking device;

[0125] Step 4: Hoist the head section into the launch pit and apply the aforementioned anti-seepage compounding agent at the port of the head section;

[0126] Step 5: Place and push in the fuselage tube sections one by one, connecting the ends of each fuselage tube section until all fuselage tube sections are installed.

[0127] When adjacent fuselage pipe sections are connected, the spigot end 5 of one fuselage pipe section is inserted into the socket end 4 of another fuselage pipe section. The spigot end 5 and the socket end 4 are connected to each other and form an installation gap.

[0128] An uninflated sealing ring 3 (made of neoprene rubber) is fitted into the installation gap. After high-pressure gas is injected into the rubber sealing ring 3, its elastic deformation pushes up the steel pipe sleeve 2 at the end of the socket, forming an effective support structure. An injection gap 1 is created between the pipe section wall and the steel pipe sleeve 2, and the drag-reducing compound is injected into the injection gap 1.

[0129] Before advancing the pipe jacking system, the inflated sealing ring 3 is deflated and contracted. The contracted outer diameter of the uninflated or deflated sealing ring 3 is less than or equal to the outer diameter of the pipe section wall, and the compression of the inflated sealing ring 3 is less than or equal to half of the inflated outer diameter of the sealing ring, with a contact pressure of more than 0.3 MPa.

[0130] Barrier slurry A1

[0131] The impermeable grout A1 in this preparation example, by mass, specifically includes the following raw materials:

[0132] 40 parts of polyurethane component

[0133] 4 parts of porous epoxy resin particles

[0134] 6 parts water glass;

[0135] The polyurethane component is an aqueous polyurethane component containing polyurethane prepolymer. By mass, 18 parts of polyether polyol 303 and 2 parts of hydroxyl-terminated polyethylene oxide are mixed evenly, and then 60 parts of diphenylmethane diisocyanate are added to obtain the prepolymer.

[0136] The porous epoxy resin particles have an average particle size of 60±5μm and an average pore size of 1000±100nm; the porous epoxy resin particles are pretreated with bis(trimethoxysilylpropyl)amine.

[0137] The polyurethane component, porous epoxy resin particles, and water glass are mixed evenly, and the above raw materials are dispersed in water to obtain a 50% (w / w) geomembrane. The isocyanate in the polyurethane component reacts with the active groups of the porous epoxy resin particles to obtain a water-soluble and homogeneous geomembrane A1.

[0138] Barrier slurry A2

[0139] The difference between the impermeable grout A2 in this preparation example and the impermeable grout A1 lies in the different raw material ratios. By mass, the raw materials for A2 specifically include:

[0140] 30 parts of polyurethane component

[0141] 5 parts of porous epoxy resin particles

[0142] 15 portions of water glass.

[0143] Barrier slurry A3

[0144] The difference between the impermeable grout A3 in this preparation example and the impermeable grout A1 lies in the different raw material ratios. By mass, the raw materials for A3 specifically include:

[0145] 35 parts of polyurethane component

[0146] 3 parts porous epoxy resin particles

[0147] 12 portions of water glass.

[0148] The material proportions of the seepage-proof grout A1-A3 are shown in Table 1:

[0149] Table 1 Material Proportions for Impermeable Grout A1-A3

[0150]

[0151]

[0152] Drag-reducing slurry B1

[0153] The drag-reducing slurry B1 in this preparation example, by mass, specifically includes the following raw materials:

[0154] 15 parts of micro / nano graphite powder

[0155] 10 parts of soda ash

[0156] 5 parts of nonionic polyacrylamide;

[0157] The average particle size of the micro-nano graphite powder is 5±1μm.

[0158] The raw materials for the drag-reducing slurry are dispersed in water to obtain drag-reducing slurry B1 with a mass concentration of 20%.

[0159] Drag-reducing slurry B2

[0160] The drag-reducing slurry B2 in this preparation example differs from drag-reducing slurry B1 in that the graphite in the raw materials is a compound graphite. The specific raw materials, by mass, include:

[0161]

[0162] The average particle size of the micro-nano graphite powder is 5±1μm.

[0163] Expanded graphite with an average particle size of 35±5μm, and polyacrylamide are pre-formed into an intercalated composite structure with expanded graphite, including the following steps:

[0164] S1-1. Expanded graphite is ultrasonically dispersed in an ethanol-water solution and treated for 15 min to obtain a graphite dispersion.

[0165] S1-2. Add polyacrylamide to graphite dispersion, stir and sonicate for 15 min to obtain polyacrylamide-graphite intercalation composite structure.

[0166] All the raw materials of the drag-reducing slurry are dispersed in water to obtain a drag-reducing slurry with a mass concentration of 20%.

[0167] Drag-reducing slurry B3

[0168] The drag-reducing slurry B3 in this preparation example differs from drag-reducing slurry B2 in that: polyacrylamide and expanded graphite are pre-formed into a composite gel, including the following steps:

[0169] S2-1. Disperse graphite in water, add acrylamide monomer and ammonium persulfate (APS), and sonicate for 10 min.

[0170] S2-2, Add tetramethylethylenediamine (TEMED) and sonicate for 3 min;

[0171] S2-3. React at 50℃ for 12 hours to obtain an aqueous polyacrylamide-graphite composite gel.

[0172] All the raw materials of the drag-reducing slurry are dispersed in water to obtain a drag-reducing slurry with a mass concentration of 20%.

[0173] Drag-reducing slurry B4

[0174] The drag-reducing slurry B4 in this preparation example differs from drag-reducing slurry B3 in the raw material ratio, which, by mass, includes:

[0175]

[0176] The material proportions of drag-reducing slurries B1-B4 are shown in Table 2:

[0177] Table 2 Material proportions of drag-reducing slurry B1-B4

[0178]

[0179] Example 1

[0180] Anti-seepage grout A1 and drag-reducing grout B1 are used to prepare anti-seepage compounding agent 1 and drag-reducing compounding agent 1, respectively.

[0181] Anti-seepage compound 1: applied between pipe sections in the head section, with the mass ratio of anti-seepage grout A1 to drag-reducing grout B1 being 80:20;

[0182] Drag-reducing compound 1: applied between two pipe sections, with the mass ratio of anti-seepage grout A1 to drag-reducing grout B1 being 30:70.

[0183] The method for constructing a pipe jacking system using the anti-seepage agent 1 and drag-reducing agent 1 in Example 1, wherein the pipe jacking system includes a head pipe section and several body pipe sections connected in sequence, and the construction method includes the following steps:

[0184] Step 1: Based on the application location of the drag-reducing and seepage-proofing agent in the pipe jacking system, prepare the seepage-proofing compound agent and the drag-reducing compound agent respectively;

[0185] Anti-seepage agent 1 is applied to the port of the head pipe section. The anti-seepage grout A1 and the drag-reducing grout B1 are mixed at a mass ratio of 80:20.

[0186] Drag-reducing compound 1 is applied to the injection gap between adjacent fuselage pipe sections. The anti-seepage grout A1 and the drag-reducing grout B1 are mixed at a mass ratio of 30:70.

[0187] Step 2: Determine the laying path of the pipe sections in the pipe jacking system and excavate the launch pit and receiving pit;

[0188] Step 3: Install the jacking device in the launch pit, hoist the tunneling device into the launch pit, and advance the tunneling device through the jacking device;

[0189] Step 4: Hoist the head section into the launch pit and apply the aforementioned anti-seepage compounding agent 1 at the port of the head section;

[0190] Step 5: Place and push in the machine body pipe sections one by one, connecting the ends of each pipe section until all pipe sections are installed. When connecting adjacent pipe sections, the spigot end of one pipe section is inserted into the socket end of another. The spigot end and socket end are connected and form an installation gap. An uninflated neoprene rubber sealing ring is placed in the installation gap. After high-pressure gas is injected into the rubber sealing ring, its elastic deformation pushes up the steel pipe sleeve at the socket end, creating an injection gap between the pipe section wall and the steel pipe sleeve. The drag-reducing compound 1 is injected into the injection gap.

[0191] Example 2

[0192] The construction method of the pipe jacking system with drag-reducing and seepage-proofing agent in the water-rich sand layer in this embodiment is the same as that in embodiment 1. The difference is that in this embodiment, seepage-proofing grout A2 and drag-reducing grout B1 are used to prepare seepage-proofing compound agent 2 and drag-reducing compound agent 2, respectively.

[0193] Anti-seepage compound 2: applied between pipe sections in the head section, with the mass ratio of anti-seepage grout A2 and drag-reducing grout B1 being 80:20;

[0194] Drag-reducing compound 2: applied between two pipe sections of the pipe body, with the mass ratio of anti-seepage grout A2 and drag-reducing grout B1 being 30:70.

[0195] Example 3

[0196] The construction method of the pipe jacking system with drag-reducing and seepage-proofing agent in the water-rich sand layer in this embodiment is the same as that in embodiment 1. The difference is that in this embodiment, seepage-proofing grout A3 and drag-reducing grout B1 are used to prepare seepage-proofing compound agent 3 and drag-reducing compound agent 3, respectively.

[0197] Anti-seepage compound 3: applied between pipe sections in the head section, with the mass ratio of anti-seepage grout A3 and drag-reducing grout B1 being 80:20;

[0198] Drag-reducing compound 3: applied between two pipe sections of the pipe body, with the mass ratio of anti-seepage grout A3 and drag-reducing grout B1 being 30:70.

[0199] Example 4

[0200] The construction method of the pipe jacking system with drag-reducing and seepage-proofing agent in the water-rich sand layer in this embodiment is the same as that in embodiment 1. The difference is that in this embodiment, seepage-proofing grout A3 and drag-reducing grout B2 are used to prepare seepage-proofing compound agent 4 and drag-reducing compound agent 4, respectively.

[0201] Anti-seepage compound 4: applied between pipe sections in the head section, with the mass ratio of anti-seepage grout A3 and drag-reducing grout B2 being 80:20;

[0202] Drag-reducing compound 4: applied between two pipe sections of the pipe body, with the mass ratio of anti-seepage grout A3 and drag-reducing grout B2 being 30:70.

[0203] Example 5-1

[0204] The construction method of the pipe jacking system with drag-reducing and seepage-proofing agent in the water-rich sand layer in this embodiment is the same as that in embodiment 1. The difference is that in this embodiment, seepage-proofing grout A3 and drag-reducing grout B3 are used to prepare seepage-proofing compound agent 5-1 and drag-reducing compound agent 5-1, respectively.

[0205] Anti-seepage compound 5-1: Apply between pipe sections in the head section, with the mass ratio of anti-seepage grout A3 and drag-reducing grout B3 being 80:20;

[0206] Drag-reducing compound 5-1: applied between two pipe sections, with the mass ratio of anti-seepage grout A3 to drag-reducing grout B3 being 30:70.

[0207] Example 5-2

[0208] The construction method of the pipe jacking system with drag-reducing and seepage-proofing agent in the water-rich sand layer in this embodiment is the same as that in embodiment 1. The difference is that in this embodiment, seepage-proofing grout A3 and drag-reducing grout B3 are used to prepare seepage-proofing compound agent 5-2 and drag-reducing compound agent 5-2, respectively.

[0209] Anti-seepage compound 5-2: Apply between pipe sections in the head section, with the mass ratio of anti-seepage grout A3 and drag-reducing grout B3 being 90:10;

[0210] Drag-reducing compound 5-2: applied between two pipe sections, with the mass ratio of anti-seepage grout A3 to drag-reducing grout B3 being 35:65.

[0211] Example 5-3

[0212] The construction method of the pipe jacking system with drag-reducing and seepage-proofing agent in the water-rich sand layer in this embodiment is the same as that in embodiment 1. The difference is that in this embodiment, seepage-proofing grout A3 and drag-reducing grout B3 are used to prepare seepage-proofing compound agent 5-3 and drag-reducing compound agent 5-3, respectively.

[0213] Anti-seepage compound 5-3: applied between pipe sections in the head section, with the mass ratio of anti-seepage grout A3 and drag-reducing grout B3 being 65:35;

[0214] Drag-reducing compound 5-3: applied between two pipe sections, with the mass ratio of anti-seepage grout A3 to drag-reducing grout B3 being 10:90.

[0215] Example 6

[0216] The construction method of the pipe jacking system with drag-reducing and seepage-proofing agent in the water-rich sand layer in this embodiment is the same as that in embodiment 1. The difference is that in this embodiment, seepage-proofing grout A3 and drag-reducing grout B4 are used to prepare seepage-proofing compound agent 6 and drag-reducing compound agent 6, respectively.

[0217] Anti-seepage compound 6: applied between pipe sections in the head section, with the mass ratio of anti-seepage grout A3 and drag-reducing grout B4 being 80:20;

[0218] Drag-reducing compound 6: applied between two pipe sections, with the mass ratio of anti-seepage grout A3 to drag-reducing grout B4 being 30:70.

[0219] The material proportions for Examples 1-6 are shown in Table 3 below:

[0220] Table 3 Material proportions for Examples 1-6

[0221]

[0222] In Table 3, "seepage prevention" refers to seepage prevention compounding agent, and "drag reduction" refers to drag reduction compounding agent. For example, "seepage prevention 1" refers to seepage prevention compounding agent 1, and "drag reduction 1" refers to drag reduction compounding agent 1.

[0223] Comparative Example 1

[0224] The construction method of the pipe jacking system with drag reduction and seepage prevention agent in the water-rich sand layer of this comparative example is the same as that in Example 1. The difference is that this comparative example only uses seepage prevention grout A3, and the seepage prevention grout A3 is applied at the port of the head pipe section and in the gap between adjacent body pipe sections.

[0225] Comparative Example 2

[0226] The construction method of the pipe jacking system with drag-reducing and seepage-proofing agent in the water-rich sand layer of this comparative example is the same as that in Example 1. The difference is that this comparative example only uses drag-reducing slurry B3, and the drag-reducing slurry B3 is applied at the port of the head pipe section and in the gap between adjacent body pipe sections.

[0227] Performance testing and results:

[0228] The drag-reducing and seepage-proofing agent samples from Examples 1-6 and Comparative Examples 1 and 2 were subjected to the following performance tests:

[0229] (1) Specific gravity:

[0230] Specific gravity, also known as relative density, is the ratio of the density of mud to the density of water in a mud sample. This experiment uses a mud hydrometer to determine the specific gravity of the mud sample.

[0231] (2) Filtration loss:

[0232] After the mud sample was prepared, it was placed into a container of a certain volume (filtration area of ​​45.8 ± 0.6 cm²). 2 By setting a pressure difference (690±35 kPa) across the two ends of the container, some of the water in the slurry will be forced into the soil. This property is called filtration loss or water loss. During construction, the water loss of the slurry is generally specified to be no more than 25 ml / 30 min.

[0233] (3) Funnel viscosity:

[0234] Funnel viscosity, also known as viscosity, refers to the resistance a fluid exhibits to its flow. When a fluid (gas or liquid) flows, resistance occurs when one part flows on top of another; this is the fluid's internal friction. Viscosity refers to the fluidity of mud. To measure using a Markov funnel viscometer, block the bottom of the funnel outlet with your finger, pour the well-stirred mud into the funnel until it reaches the bottom of the sieve; release your finger and simultaneously start a stopwatch. Stop the stopwatch when the mud has filled the measuring cup to its edge. The time shown on the stopwatch is the mud viscosity, measured in seconds (s).

[0235] (4) Water separation rate:

[0236] After the mud preparation is completed, it is placed in a graduated cylinder for 24 hours. The ratio of the volume of water precipitated from the original mud to the original drag-reducing mud volume is called the water separation rate. This index reflects the stability of the drag-reducing mud. 1000 ml of the stirred experimental mud is placed in a stoppered graduated cylinder and left to stand in a constant temperature room for 24 hours. The amount of water precipitated is recorded and converted into the water separation rate. The lower the water separation rate of the thixotropic mud, the better the stability of the slurry.

[0237] In engineering applications, anti-seepage and drag-reducing agents need to meet certain basic performance indicators. The parameter ranges of these performance indicators are shown in Table 4. The test results of Examples 1-6 and Comparative Examples 1 and 2 of this invention are shown in Table 5.

[0238] Table 4 Reference values ​​of technical parameters for performance indicators

[0239] Technical parameters Specific gravity (g / cm3) 3 )]]> Fluid loss (ml / 30 min) Funnel viscosity (s) Water separation rate (%) Reference value 1.1～1.6 ≤25 ≥30 Tendency 0

[0240] Table 5. Test results of drag-reducing and seepage-proofing agent performance indicators.

[0241]

[0242]

[0243] Referring to Table 4, as can be seen from the data in Table 5, the drag-reducing and seepage-proofing agents in each embodiment of the present invention are configured according to the requirements of different application locations, and their performance is flexibly adjustable within a certain range, exhibiting good overall performance indicators. For example, each embodiment shows a low filtration loss, especially the filtration loss of the seepage-proofing compound agent is below 7.5 ml / 30 min, and the filtration loss of the drag-reducing compound agent is also below 25 ml / 30 min, effectively curbing the abnormal infiltration of water inside the mud jacket into the surrounding soil. Simultaneously, with the proper adjustment of specific gravity and viscosity under the combination of seepage-proofing grout and drag-reducing grout, good thixotropic properties are demonstrated; the water separation rate of the samples in each embodiment is below 5%, especially the water separation rate of the seepage-proofing compound agent, which is further reduced to below 3%, reflecting its good stability. It can be well applied in large-diameter pipe jacking construction, saving materials, reducing costs, and causing no environmental pollution. Overall, by modifying and combining the materials of the impermeable grout and drag-reducing grout, and by proposing reasonable formulations of the impermeable grout and drag-reducing grout according to different application requirements, the resulting impermeable and drag-reducing agents exhibit flexible configuration adaptability. They also have better fluidity, dispersibility and lower water loss while having high viscosity, resulting in better drag reduction and impermeability performance that is easy to control.

[0244] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A drag-reducing and seepage-preventing agent for pipe jacking construction in water-rich sandy layers, characterized in that, The drag-reducing and seepage-proofing agent includes seepage-proofing grout and drag-reducing grout; The raw materials of the impermeable grout, by weight, include: 30-40 parts of polyurethane component 2-5 parts epoxy resin 5-15 parts of inorganic materials; The raw materials for the drag-reducing slurry, by weight, include: 10-15 parts graphite 10-15 parts of soda ash 2-5 parts of polyacrylamide; The raw materials of the impermeable grout are dispersed in water to obtain an impermeable grout with a mass concentration of 30-50%. The raw materials for the drag-reducing slurry are dispersed in water to obtain a drag-reducing slurry with a mass concentration of 5-20%. The impermeable grout and the drag-reducing grout are mixed at a mass ratio of (1-99):(99-1) to obtain the drag-reducing and impermeable agent; The epoxy resin comprises porous epoxy resin particles, which are pretreated with a silane coupling agent containing isocyanate reactive groups.

2. The drag-reducing and seepage-proofing agent as described in claim 1, characterized in that, By weight, the polyurethane component comprises the following raw materials: 50-100 parts of isocyanate 10-50 parts of polyol 1-5 parts of terminal hydroxyl compound, The process involves first mixing the polyol and the terminal hydroxyl compound evenly, then adding the isocyanate and optional additives to prepare an aqueous polyurethane component containing polyurethane prepolymer.

3. The drag-reducing and seepage-proofing agent as described in claim 2, characterized in that, The average particle size of the porous epoxy resin particles is 30-100 μm, and the average pore size is 10 to 2,000 nm. The inorganic material includes one or more of cement, controllable clay, and water glass; The inorganic material is pretreated with a silane coupling agent, which contains isocyanate reactive groups.

4. The drag-reducing and seepage-preventing agent according to any one of claims 1-3, characterized in that, The polyacrylamide comprises: One or more of cationic polyacrylamide, anionic polyacrylamide, and nonionic polyacrylamide; Graphite is a composite of micro-nano graphite powder with a particle size of 1-10 μm and expanded graphite with a particle size of 20-50 μm, wherein the mass ratio of the micro-nano graphite powder to the expanded graphite is (10-20):(1-5).

5. The drag-reducing and seepage-proofing agent as described in claim 4, characterized in that, The polyacrylamide and the expanded graphite are pre-formed into an intercalated composite structure, comprising the following steps: S1-1. The expanded graphite is ultrasonically dispersed in an aqueous ethanol solution to obtain a graphite dispersion. S1-2. The polyacrylamide is added to the graphite dispersion, stirred and ultrasonically treated to obtain a polyacrylamide-graphite intercalation composite structure.

6. The drag-reducing and seepage-proofing agent as described in claim 4, characterized in that, The pre-formation of a composite gel between the polyacrylamide and the expanded graphite includes the following steps: S2-1. Disperse graphite in water, add acrylamide monomer and ammonium persulfate, and sonicate for 10-20 minutes. S2-2, Add tetramethylethylenediamine and sonicate for 2-5 minutes; S2-3. React at 40-60℃ for 2-24 hours to obtain aqueous polyacrylamide-graphite composite gel.

7. A method for preparing the drag-reducing and seepage-proof agent as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Prepare the impermeable grout: Weigh the raw materials for the anti-seepage grout according to the preset ratio; The raw materials for the seepage-proof grout are dispersed in water and mixed evenly to form a seepage-proof grout with a mass concentration of 30-50%. S2. Prepare drag-reducing slurry: Weigh the raw materials for the drag-reducing slurry according to the preset proportions; The raw materials for drag-reducing slurry are dispersed in water and mixed evenly to form a drag-reducing slurry with a mass concentration of 5-20%. S3. Mix the impermeable grout and the drag-reducing grout at a mass ratio of (1-99):(99-1) to obtain the drag-reducing and impermeable agent.

8. A construction method for a pipe jacking system using the drag-reducing and seepage-preventing agent according to any one of claims 1-6, characterized in that, The pipe jacking system includes a head pipe section and several body pipe sections connected in sequence, and the construction method includes the following steps: Step 1: Based on the application location of the drag-reducing and seepage-proofing agent in the pipe jacking system, prepare the seepage-proofing compound agent and the drag-reducing compound agent respectively; An anti-seepage compounding agent is used, wherein the anti-seepage grout and the drag-reducing grout are mixed at a mass ratio of (65-90):(10-35); A drag-reducing compounding agent is used, wherein the impermeable grout and the drag-reducing grout are mixed at a mass ratio of (10-35):(65-90); Step 2: Determine the laying path of the pipe jacking system segments and excavate the tunnel; Step 3: Install the jacking device and the tunneling device in the tunnel, and use the jacking device to advance the tunneling device; Step 4: Install the head pipe section in the tunnel, and apply the aforementioned anti-seepage compounding agent at the port of the head pipe section; Step 5: Push in the fuselage tube sections one by one, connecting the ends of each fuselage tube section until all fuselage tube sections are installed. During this process, apply the drag-reducing compound between each fuselage tube section.

9. The construction method of the pipe jacking system as described in claim 8, characterized in that, In step five, each body pipe section includes a spigot end and a socket end at both ends. The spigot ends and socket ends of adjacent body pipe sections are inserted and fitted to form an installation gap. A steel pipe sleeve and a sealing ring are installed in the installation gap. The sealing ring is inflated and expands, creating an injection gap between the pipe section wall and the steel pipe sleeve. The drag-reducing and seepage-proof agent is applied to the injection gap. Afterward, the inflated sealing ring is deflated and shrinks.

10. The construction method of the pipe jacking system as described in claim 9, characterized in that, The outer diameter of the sealing ring after it is not inflated or deflated is less than or equal to the outer diameter of the pipe section wall. The compression amount of the sealing ring after inflation is less than or equal to half of the outer diameter of the sealing ring after inflation.

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