Fabricated wharf structure and construction method therefor

Abstract

The present invention relates to a fabricated wharf structure, comprises a prefabricated concrete pile cap unit, composite pile foundation assembly and elastic fender module: pile cap unit is poured with fiber reinforced concrete with a fiber volume content of 1.2%—l.8%, a trapezoidal steel rail with a fiber content of 1.5-2.0 kg / m3 is pre-embedded in a side, nano—silica modified with methyl trimethoxysilane has a particle size of 10-20 nm and specific surface area of 180-220 mZ / g, is 3-5% of a mass of a cementing material, a polyurea waterproof layer of 2.0-2.5 mm is coated on a surface of a joint; composite pile foundation is a prestressed concrete pipe pile doped with 0.8%-1.2% silane corrosion inhibitor, and an anchoring steel bar with an epoxy resin coating is pre-embedded in a pile top. The structure is suitable for wharf construction in marine environment, and has long-term corrosion resistance, excellent impermeability and buffering performance.

Description

TECHNICAL FIELD The present invention belongs to the technical eld of port engineering construction, and particularly to a fabricated wharf structure and a construction method therefor. BACKGROUND In wharf engineering in marine environment, a traditional fabricated structure has the problems of joint leakage, pile foundation corrosion and an insufficient fender performance in a long run. Firstly, a joint between prefabricated concrete pile cap units is generally lled with common epoxy mortar, but under a dryingwetting cycle in a tidal range region and a repetitive action of a ship load, the joint is prone to water seepage due to material shrinkage or microcrack expansion. The common epoxy mortar lacks an effective anti-crack reinforcement phase, and a seawater infiltration path is not optimized, so that chloride ions invade along the joint and then accelerate the corrosion of internal steel bars. In the prior art, when trying to add a ber material, a reinforcement effect is often limited due to uneven fiber dispersion or insufficient interfacial bonding, While improper selecting and doping methods of a hydrophobic material may reduce a compactness degree of the mortar, which further aggravates a leakage risk. In addition, a waterproof layer on a surface of the joint is often failed quickly under ultraviolet light and mechanical wear due to poor weather resistance or an uneven construction thickness of the material, so that it is difcult to form lasting sealing. Secondly, a prestressed concrete pipe pile is vulnerable to chloride ion corrosion and sulfate corrosion in marine environment, and traditional anti-corrosive measures mostly adopt a single silane dipping or epoxy coating, but there are obvious limitations. When a silane dipping depth is insufficient (usually less than 5 mm), pores inside a pile body still provide channels for a corrosive medium. However, it is difcult for a single silane component to give consideration to both permeability and hydrophobic durability, and hydrolysis failure is easy to occur under long-term immersion. In addition, a weak interface is formed at a junction between an anchoring steel bar at a pile top andconcrete due to material heterogeneity, and if there are micropores or construction defects in a traditional epoxy coating, local points are corroded, leading to stress corrosion cracking. In the prior art, an increase of a silane treatment depth depends on high-pressure equipment, but a compactness degree difference of the concrete will lead to uneven inltration, and excessive pressurization may damage a pile body structure. However, a ne anticorrosive treatment of an interface is limited by construction conditions and cost control, so that it is difcult to realize large-scale application. Finally, a traditional fender module is mostly made of a single rubber material or a simple composite material, and it is difcult to balance energy absorption efciency and durability of the fender module. The single rubber material is prone to aging and hardening under long-term ultraviolet irradiation and seawater immersion, which reduces a buffering performance. However, although an ordinary foam material can improve an energy absorption effect, an insufcient percentage of close area leads to an increase of a water absorption rate, which increases a self-weight and accelerates internal corrosion. In addition, the mechanical connection between the fender module and the pile cap structure is often realized by bolt xation or glue bonding, and a bolt hole position is easy to cause concrete cracking due to stress concentration, while an interface of glue bonding is easy to be stripped in hygrotherrnal environment. A composite elastomer structure tried in the prior art is often subjected to a layered damage under repeated impact due to an insufcient interlayer bonding strength, and lacks an adaptive connection design with the pile cap, leading to difcult maintenance and replacement. These problems jointly restrict the service life and safety of a wharf structure in complex marine environment. SUMMARY One objective of the present invention is to solve the problems of poor waterproofness of a joint, insufcient corrosion resistance of a pile foundation and a limited energy absorption effect of a fender module in a traditional wharf structure. The present invention solves the problems of insufcient crack resistance of epoxy mortar and poor dispersion uniformity of a nano-material. The present invention solves the problems of an insufcient connection strength between fabricated pile caps and poor mounting reliability of a fender module. The present invention solves the problem of poor multiscale reinforcement effect and interfacial bonding of ber reinforced concrete. The present invention solves the control problem of durability optimization and curing technology of a concrete matrix. The present invention solves the balance problem of lm forming quality and weatherability of a polyurea coating. The present invention solVes the dynamic adjustment problem of construction parameters of the coating in complex environment. The present invention solves the optimization problem of an inltration depth and a compound ratio of a silane corrosion inhibitor. The present invention solves the problem of poor multimaterial cooperative corrosion prevention and sealing at an interface of a pile top. The present invention solves the problems of multiprocess quality control and interface treatment in a construction process. The present invention provides a fabricated wharf structure, which comprises: a prefabricated concrete pile cap unit, a composite pile foundation assembly and an elastic fender module, wherein the prefabricated concrete pile cap unit is formed by pouring ber reinforced concrete with a ber volume content of l.2%-l.8%, and a trapezoidal steel rail is pre-embedded in a side surface of the pile cap unit; a joint between the prefabricated concrete pile cap units is lled with epoxy mortar, and a polyurea waterproof coating is applied on a surface of the cured epoxy mortar, which has a coating thickness of 2.0-2.5 mm; the composite pile foundation assembly is a prestressed concrete pipe pile, pile body concrete is doped with a silane corrosion inhibitor, a content of the silane corrosion inhibitor is 0.8%-l.2% of a total mass, an anchoring steel bar is preembedded in a pile top, and a surface of the anchoring steel bar is coated with an epoxy resin layer; and the elastic fender module is made of closed-cell rubber and a polyurethane composite elastomer, a back surface of the module is provided with a Tshaped embedding groove, a depth of the embedding groove is 1 / 3 of a thickness of the module, and the Tshaped embedding groove is connected to a trapezoidal steel rail; wherein, the closed-cell rubber and the polyurethane composite elastomer of the elastic fender module adopt a three-layer composite structure, wherein an outer layer is a weather-resistant polyurethane layer, a middle layer is a closed-cell rubber foam, and an inner layer is a high-damping butyl rubber layer; the three layers are bonded by vulcanization to form a whole; a chopped basalt ber and hydrophobic nanosilica are added into the epoxy mortar, the chopped basalt ber has a length of 1215 mm and a ber diameter of 7-9 um, a surface of the ber is treated with a silane coupling agent, and a content of the ber is 1.5-2.0 kg / m3; and the hydrophobic nano-silica has a particle size of 10-20 nm and a specic surface area of 180-220 mZ / g, a content of the nanosilica is 35% of the total mass, the nanosilica is hydrophobically modied with methyl trimethoxysilane, and a content of the modier is 15-20% of a mass of the nano-silica. Preferably, according to the fabricated wharf structure of the present invention, a matrix of the epoxy mortar is formed by mixing bisphenol A epoxy resin and a polyamide curing agent according to a mass ratio of 2: l, and 3040% quartz sand aggregate by mass is added into the resin matrix, which has an aggregate particle size of O. 1-03 mm; and during manufacturing, when the epoxy mortar is stirred, the ber is added and dispersed for 5-8 minutes rst, then the nano-silica is added to continuously stir for 3-5 minutes, a curing temperature is controlled at 15-30°C, and a curing humidity is 570%. Preferably, according to the fabricated wharf structure of the present invention, a single pile cap unit has a length of 6-8 m and a width of 4-5 m, a steel connecting plate with a galvanized coating is preembedded in a joint between adjacent pile cap units, and the connecting plate has a thickness of 12-15 mm, and is transversely connected through an M24 high-strength bolt; and an outer diameter of the pipe pile is 800-1000 mm; when the prefabricated concrete pile cap unit is mounted, a pile hole with a diameter of 120 mm is reserved in a bottom portion, C45 underwater non-dispersible concrete is poured into the pile hole, the anchoring steel bar of the composite pile foundation assembly is inserted into the concrete of the pile hole, and an exposed length of the anchoring steel bar is 300-350 mm; and the elastic fender module is slidably embedded with the trapezoidal steel rail pre-embedded in the side surface of the pile cap unit through the Tshaped embedding groove, a cross section height of the steel rail is 80-100 mm, and an anti-falling pin with a diameter of 16 mm is used for penetration and xation after embedding. Preferably, according to the fabricated wharf structure of the present invention, in the ber reinforced concrete of the prefabricated concrete cap unit, the ber is a mixed composite ber, comprising an end-hook steel ber with a length of 12-15 mm, which has a diameter of 02-025 mm and a length-diameter ratio of 60-75, and a polypropylene reticular ber with a length of 18-22 mm, which has an equivalent diameter of 0.02-0.04 mm and a length-diameter ratio of450-550, a volume content of the steel ber is 0.8%-1.0%, and a volume content of the polypropylene ber is 0.4%-0.8%; and a surface of the steel ber is treated with a zinc phosphate anti-corrosive coating, which has a coating thickness of 35 um, and the polypropylene ber is subjected to plasma etching to form a micron-level rough surface. Preferably, according to the fabricated wharf structure of the present invention, the concrete matrix adopts P0 42.5 Portland cement, a coarse aggregate is continuously graded broken stone of 510 mm, a ne aggregate is medium sand with a neness modulus of 2.62.9, a waterbinder ratio is 0.320.35, and 15-20% Grade II y ash and 5-8% silica fume based on a total mass of a cementing material are doped; and after pouring, the concrete is cured by steam at 40-45°C for 24-36 hours, and then naturally cured for a period of 28 days. Preferably, according to the fabricated wharf structure of the present invention, the polyurea waterproof coating is a twocomponent reactive coating, which is formed by mixing an isocyanate component A and an amino resin component B according to a volume ratio of l: 1 and spraying the mixture, wherein the component A contains an aliphatic isocyanate prepolymer with an NCO content of 1820%, and 0.51.0% benzotriazole ultraviolet absorber by mass and the component B contains an aminoterminated polyether with a molecular weight of 20002500, 20-30% nano-alumina wear-resistant ller by mass with a particle size of 50-80 nm, and 0.3-0.5% silane coupling agent by mass. Preferably, according to the fabricated wharf structure of the present invention, the coating is sprayed in two stages, a spraying thickness of a bottom layer is 0.81.2 mm, and after an interval of 10-15 minutes, a top layer is sprayed to a total thickness of 2.0-2.5 mm; during spraying, a temperature of a base surface is controlled at 15-35°C, a spraying pressure is 18-22 MPa, and a moving speed of a spray gun is 0.5-0.8 m / s; in pre-treatment of the base surface: after the epoxy mortar is cured, the surface is sandblasted to a roughness degree of Sa2.5 grade, the base surface is cleaned and dehumidied within 4 hours after sandblasting, and a water content of the base surface is 5 3%; in gradient temperature control: the base surface is preheated before spraying, a preheating temperature is 58OC higher than an ambient temperature, the temperature of the base surface is dynamically maintained in a range of 1535°C, when the ambient temperature is lower than 15°C, an infrared radiation heater is used for compensation, and when the ambient temperature is higher than 35°C, an atomized water curtain is used for cooling; in staged pressure adjustment: when the bottom layer is sprayed, the pressure is set to be 18-20 MPa, the moving speed of the spray gun is 0.7-0.8 m / s, and a continuous thin layer is formed; and when the top layer is sprayed, the pressure is increased to 21-22 MPa, the moving speed of the spray gun is reduced to 0.50.6 m / s, and directional arrangement of a nanoalumina ller is enhanced; in trajectory optimization: the spray gun is kept vertical to the base surface, a spraying distance is 300-350 mm, a swing amplitude of the spray gun is 550 mm, and an overlapping Width of adjacent spraying belts is 1 / 31 / 2 of a spraying swath width; and in curing monitoring: a surface temperature of the coating is monitored within 30 minutes after spraying, a heating rate is controlled at 55°C / min, a peak temperature is 560°C, and a relative humidity during curing is 575%. Preferably, according to the fabricated wharf structure of the present invention, the silane anti-corrosive agent doped in the pile body concrete of the composite pile foundation assembly is a twocomponent composite silane, which contains isobutyl triethoxysilane accounting for 60-70% by mass and octyl trimethoxysilane accounting for 30-40% by mass, and a total content of the silane anticorrosive agent is 0.8%-1.2% of the total mass of the cementing material. Preferably, according to the fabricated wharf structure of the present invention, the silane anticorrosive agent is injected into the pile body concrete by a vacuum pressure impregnation method, an impregnation pressure is 0.5-0.8 MPa, impregnation time is 23 hours, and the concrete is cured at normal temperature for 48 hours after impregnation; a coarse aggregate of the pile body concrete is granite gravel with a particle size of 1020 mm, a ne aggregate of the pile body concrete is river sand with a neness modulus of 2.3-2.6, a water-binder ratio is 0.28-0.32, and 8-12% slag powder and 58% metakaolin based on the total mass of the cementing material are doped; and after silane treatment, a surface water absorption rate of the pile body concrete is 50.01 mm / min1 / 2, a chloride ion migration coefcient is S3.0><1012 m2 / s, and a sulfate corrosion resistance grade is ZKSISO; and A transitional sealing belt is arranged at a junction between the epoxy resin coating and the silane treatment layer of the anchoring steel bar in the pile top, and the sealing belt is made of a silane modied polyurethane colloid, which has a width of 15-20 mm and a thickness of 1.0-1.5 mm, and is formed by continuous coating. Preferably, a construction method for the fabricated wharf structure of the present invention comprises the following steps: forming the prefabricated concrete pile cap unit by pouring the ber reinforced concrete with the ber volume content of l.2%-l.8%, and pre-embedding the trapezoidal steel rail in the side surface of the pile cap unit; lling the epoxy mortar in the joint between adjacent prefabricated concrete pile cap units, adding the chopped basalt ber with the length of 1215mm and the diameter of 79 um and the hydrophobic nano-silica into the epoxy mortar, treating the surface of the chopped basalt ber with the silane coupling agent, wherein the ber content is 1.5-2.0 kg / m3, the hydrophobic nano-silica has the particle size of 10-20 nm and the specic surface area of 180-220 mZ / g, the content of the nanosilica is 35% of the total mass of the cementing material, and hydrophobically modifying the nano-silica with the methyl trimethoxysilane, wherein the content of the modier is 15-20% of the mass of the nanosilica; applying the polyurea waterproof coating on the surface of the joint after the epoxy mortar is cured, and controlling the coating thickness at 2.02.5 mm; when preparing the composite pile foundation assembly, doping the silane corrosion inhibitor into the pile body concrete of the prestressed concrete pipe pile, the content of the silane corrosion inhibitor is 0.8%-1.2% of the total mass of the cementing material, pre-embedding the anchoring steel bar in the pile top, and coating the surface of the anchoring steel bar with the epoxy resin layer; when preparing the elastic fender module, making the threelayer composite structure with the closed-cell rubber and the polyurethane composite elastomer, wherein the outer layer is the weather-resistant polyurethane layer, the middle layer is the closed-cell rubber foam, and the inner layer is the high-damping butyl rubber layer, bonding the three layers by vulcanization to form a whole, and processing the T-shaped embedding groove with the depth of 1 / 3 of the thickness of the module on the back surface of the module; and embedding the Tshaped groove of the elastic fender module with the trapezoidal steel rail on the side surface of the prefabricated concrete pile cap unit. The present invention comprises at least the following benecial effects. Through the multi-scale ber reinforced concrete, the nano-modied epoxy mortar and the gradient composite fender structure, an impermeability grade of the joint is improved to P12, a chloride ion diffusion coefcient of a pile foundation is reduced by 80%, and energy absorption efciency of a fender is improved by 65%. Through an optimized stirring technology, a ber dispersion degree reaches 92%, a nano-particle agglomeration rate is reduced to 3%, a exural strength of the mortar is increased by 40%, and a toughness index reaches 35. Through combined connection, a shear strength of the joint between the pile caps reaches 25 MPa, a mounting error of the fender module is controlled within il mm, and impact fatigue resistance life is increased to 1 million times. Through a mixed ber system, a concrete compression strength is increased by 28%, a exural toughness index reaches 150, and a crack width is controlled within 0.1 mm. Through the optimization of a mix proportion and a curing technology, a compactness degree of the concrete is increased by 30%, a number of freeze-thaw resistance cycles reaches 300, and a shrinkage rate is reduced by 45%. Wear resistance of the nano-reinforced polyurea coating is improved by 5 times, a tensile strength retention rate is 95% after ultraviolet aging, and salt spray corrosion resistance time is more than 5000 hours. Through the adjustment of ne construction parameters, a coating thickness uniformity error is 35%, and an interfacial bonding strength reaches 3.5 MPa, which remains 2.8 MPa after hygrothermal aging. Through a bissilane composite system, the inltration depth reaches 15 mm, the water absorption rate is reduced by 90%, and corrosion resistance life is prolonged to more than 30 years. Through the interfacial sealing belt, a chloride ion permeability is reduced by 98%, and the interfacial bonding strength is improved to 4.2 MPa, thus effectively preventing electrochemical corrosion. Through whole-process quality control, construction efciency is improved by 40%, and a qualication rate of key process reaches 99.2%, thus realizing long-term reliability of the wharf structure in marine environment. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of one embodiment of the present application. In the drawing, 2 refers to prefabricated concrete pile cap unit; 1 refers to composite pile foundation assembly; and 3 refers to elastic fender module. DETAILED DESCRIPTION The present invention is further described in detail hereinafter with reference to the drawings, so that those skilled in the art can implement according to the specication. According to one embodiment of the present invention, in ber reinforced concrete of a prefabricated concrete pile cap unit 2, a ber volume content may be 1.2%, 1.5% or 1.8%, and a specic value may be adjusted according to a corrosion level of marine environment. Nano-silica has a particle size of 10-20 nm and a specic surface area of 180-220 mZ / g, a content of the nano-silica is 3%, 4% or 5% of a total mass of a cementing material, and the nanosilica is modied with methyl trimethoxysilane. A thickness of a polyurea waterproof coating may be 2.0 mm, 2.3 mm or 2.5 mm, and a temperature of a base surface is controlled at 15-35°C during spraying. A trapezoidal steel rail may be made of Q235B galvanized steel, which has a cross section height of 80 mm, 90 mm or 100 mm, and is pre-embedded in a center line position of a side surface of the pile cap unit. A chopped basalt ber with a length of 1215 mm and a diameter of 79 um may be added into epoxy mortar, a surface of the ber is treated with a silane coupling agent, and a content of the ber is 15-20 kg / m3. The trapezoidal steel rail is xed in a formwork by a positioning xture before concrete pouring, a joint is cleaned and then lled with the epoxy mortar, and the epoxy mortar is leveled and cured for 24 hours. A polyurea coating is sprayed in two stages, a thickness of a bottom layer is 0.81.2 mm, and after an interval of 10-15 minutes, a top layer is sprayed to a total thickness of 2.0-2.5 mm. Spraying equipment may be a Graco XM series high-pressure airless spray machine, a moving speed of a spray gun is 0.5-0.8 m / s, and a spraying distance is 300-350 mm. The nanosilica may be purchased from DEGUSSA Aerosil R812, and the methyl trimethoxysilane modier is selected from a commercially available KH570 model. A ber content is accurately controlled by an electronic scale, and an error is not greater than i0.l%. According to a chloride ion permeability test (ASTM C1202), a permeability coefcient of a joint specimen is 31.5><1012 mi / S. 2000 hours after an articial aging test (GB / T 1865), the polyurea coating has no cracking or peeling. This design improves crack resistance of the pile cap unit by 30%-40%, and prolongs waterproof life of the joint to more than 20 years. In a prestressed concrete pipe pile of a composite pile foundation assembly 1, a content of a silane corrosion inhibitor may be 0.8%, 1.0% or 1.2%, and the silane corrosion inhibitor is compounded by isobutyl triethoxysilane (60%-70%) and octyl trimethoxysilane (30%-40%). An anchoring steel bar in a pile top is an HRB400 grade rebar, which has a diameter of 25 mm and an exposed length of 300 mm, 325 mm or 350 mm, a surface of the anchoring steel bar is coated with an epoxy resin layer, and a dry lm thickness is 2200 um. An outer diameter of the pipe pile may be 800 mm, 900 mm or 1000 mm, a coarse aggregate of pile body concrete is granite gravel of 10-20 mm, and a ne aggregate of the pile body concrete is river sand with a neness modulus of2.3-2.6. The silane corrosion inhibitor is injected into the pipe pile through vacuum pressure impregnation equipment (such as a ZKY100 model) at an impregnation pressure of 0.5-0.8 MPa for 2-3 hours, and the pipe pile is cured at normal temperature for 48 hours. Before mounting, the anchoring steel bar is derusted by sandblasting to Sa2.5 grade, and the epoxy resin coating may be twocomponent SikaTop Seal107, which is painted in two stages at an interval of 2 hours. A transitional sealing belt at the pile top may be made of a silane modied polyurethane colloid, which has a width of 15-20 mm and a thickness of 1.01.5 mm, and is continuously coated at a junction between the epoxy resin coating and the silane layer. After silane treatment, a surface water absorption rate of the pipe pile is 30.01 mm / minl / 2 (GB / T 1462), and a chloride ion migration coefcient is 33.0X1012 mZ / s (ASTM C 1556). 1000 hours after a salt spray test (GB / T 10125), there is no corrosion, and an interfacial shear strength of the anchoring steel bar is 225 MPa. This design makes service life of a pile foundation in marine environment reach more than 50 years. In a three-layer composite structure of an elastic fender module 3, an outer layer may be made of weather-resistant polyurethane (with a hardness degree of 90A), a middle layer is made of a closed-cell EPDM polyfoam board (with a density of 0.6 g / cm3), and an inner layer is made of highdamping butyl rubber (with a loss factor of 20.3). A depth of a T-shaped embedding groove is 30%, 33% or 35% of a thickness of the module, and a width of the groove is matched with a cross section of the trapezoidal steel rail. An antifalling pin is a 304 stainless steel pin with a diameter of 16 mm, 18 mm or 20 mm, a surface of the pin is galvanized, and shear resistance of the pin is 250 kN. The embedding groove in a back surface of the module is processed by a CNC machine tool, with a tolerance of i0.5mm. When the fender module is mounted, the Tshaped embedding groove horizontally slides in a design position along the trapezoidal steel rail on the side surface of the pile cap unit, a pin hole is aligned, and then the anti-falling pin is inserted into the pin hole and xed by a locking nut. Parameters of a vulcanization technology comprise a temperature of 150°C, a pressure of 10 MPa and time of 30 minutes, and it is veried by a peeling test (GB / T 2791) that a bonding strength is 28 kN / m. The polyurethane material may be purchased from Bayer Desmopan DP 9370A, and the butyl rubber is Exxon Mobil IIR 0650. A drop hammer impact test (J T / T 4) shows that energy absorption efciency of the module is 285%, and 500 hours after an ultraviolet aging test (GB / T 16422.3), a hardness change is 55%. A tensile strength of connection by the Tshaped embedding groove is 215 kN, and maintenance and replacement time is reduced by 60% compared with connection by a traditional bolt. This design improves a buffering performance of a fender system by 40%-50% under an impact of ship berthing. According to another embodiment of the present invention, a matrix of the epoxy mortar is formed by mixing bisphenol A epoxy resin and a polyamide curing agent according to a mass ratio of 2: l. The bisphenol A epoxy resin may be commercially available E44 epoxy resin (with an epoxy value of 0.44), and the polyamide curing agent may be a lowmolecular polyamide curing agent of model 651. After the resin is mixed with the curing agent, the mixture needs to stand for 3-5 minutes to eliminate bubbles. A quartz sand aggregate added into the resin matrix has a particle size of 0.10.3 mm and a mass fraction of 3040%, such as a mass fraction of 35%. The quartz sand aggregate may be natural quartz sand conforming to GB / T14684 standard, which has a silica content of 298%. Before adding, the aggregate needs to be screened to a target particle size range, and dried at 80°C until a water content is 30.5%. When the epoxy mortar is stirred, a planetary mixer (such as HJS200) is used, and a stirring speed is set to be 120-150 r / min. The chopped basalt ber has a content of 1.5-2.0 kg / m3, a ber length of 1215 mm and a diameter of 7-9 um, such as a TSCF-l2 ber of Nanjing Tianshi New Material Technologies Co., Ltd. The ber needs to be dispersed in the resin matrix in advance, and stirred for 5-8 minutes, such as 6 minutes. Subsequently, the hydrophobic nanosilica (such as Evonik AEROSIL R812S, which has a particle size of 12 nm and a specic surface area of 220 mZ / g) is added, and continuously stirred for 3-5 minutes, such as 4 minutes. After stirring, the epoxy mortar needs to complete joint lling construction within 20 minutes to avoid initial setting. A curing temperature of the epoxy mortar is controlled at 15-30°C, such as 25°C, and a curing humidity of the epoxy mortar is 370%. A temperature and humidity control chamber (such as a Keming HWS-100 constant temperature and humidity chamber) may be used in curing environment, and a curing period is 7 days. Mechanical vibration or an abrupt change of a temperature difference needs to be avoided in the curing period. If an ambient temperature is lower than 15°C, a curing region may be wrapped by an electric blanket, and a heating rate is 3 5°C / h; and if a humidity is greater than 70%, the humidity may be adjusted with a silica gel absorbent. After curing, the epoxy mortar has a 28-day compressive strength of 260 MPa, a tensile strength of 28 MPa and a chloride ion permeability coefcient of 31 .5>< 1012 m2 / s. By optimizing the ratio of the epoxy mortar, the stirring technology and the curing conditions, the crack resistance, compactness and durability of the joint lling material can be improved. The quartz sand aggregate enhances the rigidity of the matrix, the ber and the nanosilica cooperatively inhibit the expansion of a micro-crack, and the polyamide curing agent ensures the full crosslinking of the resin. Strict temperature and humidity control can reduce a shrinkage stress, and nally, long-term imperrneability and chloride ion corrosion resistance of the joint are realized, thus meeting requirements for working conditions of dry-wet altemation and load impact in marine environment. According to another embodiment of the present invention, a mixed composite ber comprises an endhook steel ber and a polypropylene reticular ber. The endhook steel ber may have a length of 12 mm, 14 mm or 15 mm, a diameter of 0.2 mm, 0.22 mm or 0.25 mm, and a length-diameter ratio of 60, 65 or 75; and the polypropylene reticular ber may have a length 18 mm, 20 mm or 22 mm, an equivalent diameter of 0.02 mm, 0.03 mm or 0.04 mm, and a lengthdiameter ratio of 450, 500 or 550. A volume content of the steel ber may be 0.8%, 0.9% or 1.0%, and a volume content of the polypropylene ber may be 0.4%, 0.6% or 0.8%. The ber may be an end-hook steel ber (model GX-12) produced by a company in Jiangsu and a polypropylene reticular ber (model PP-20) provided by a company in Zhejiang. In a concrete stirring process, the steel ber and the polypropylene ber are added into a mixer in batches, wherein the steel ber is added to stir for 2 minutes rst, and then the polypropylene ber is added to continuously stir for 3 minutes to ensure uniform dispersion. Parameters are set according to results of a concrete crack resistance test: crack width control effects under different ber contents are determined by a three-point bending test, and an optimal content is selected when a crack width is 50.1 mm. Raw materials are from domestic building material suppliers, and a ber surface treatment agent may be a zinc phosphate coating material (model PZ5) purchased from a chemical enterprise in Shanghai. An experimental object is a C40 concrete test block. The surface of the steel ber may be applied with a zinc phosphate anti-corrosive coating, a coating thickness may be 3 um, 4 um or 5 um, a coating material may be a zinc phosphate waterbased paint (model PH-3C) produced by a company in Wuhan, and the coating is dried at 80°C for 30 minutes after spraying. The polypropylene ber is treated by plasma etching through equipment of a low-temperature plasma processor (model PT200) from a company in Beijing, wherein treatment time is set to be 5 minutes and treatment power is 200 W, and after etching, an Ra value of surface roughness of the ber reaches 1.21.5 um. In the concrete, the steel bers are mainly distributed in a tensioned region of the pile cap unit, and the polypropylene bers are evenly distributed in the concrete matrix to improve overall crack resistance. The coating thickness is detected by scanning electron microscopy (SEM) to ensure intact coverage. Plasma etching parameters are optimized according to a ber surface contact angle test, and a target contact angle is 330°, so as to enhance a bonding force with the concrete. A functional test comprises a ber pull-off experiment, and results show that the bonding strength between the steel ber and the concrete is improved by lS%-20% and the interfacial shear strength of the polypropylene ber is improved by 10%-12%. The concrete matrix adopts P0 42.5 Portland cement, a coarse aggregate is continuously graded broken stone of 510 mm, a ne aggregate is river sand with a neness modulus of 2.6, 2.8 or 2.9, and a water-binder ratio may be 0.32, 0.33 or 0.35. In an admixture, a content of y ash may be 15%, 18% or 20%, and a content of silica fume may be 5%, 6% or 8%. During construction, the concrete is stirred by a forced double-horizontal-shaft mixer (model J S-750), and the aggregate and the cement are drymixed for 1 minute rst, then added with water and the admixture to stir for 2 minutes, and nally added with the ber to stir for 3 minutes. After concrete pouring, a steam curing temperature is controlled at 40°C, 42°C or 45°C, and curing time is 24 hours, 30 hours or 36 hours, and then the concrete is naturally cured for a period of 28 days. Aggregate gradation is determined by a screening test, and the y ash conforms to a grade 11 standard in Fly Ash Used For Cement and Concrete (GB / T 15962017). The curing temperature is monitored in real time by a digital temperature controller (model TC-200), and the humidity is controlled at 370% by a humidity sensor (model HS-1101). Experimental data show that a 28day compressive strength of the optimized concrete reaches 5055 MPa, and a chloride diffusion coefcient of the optimized concrete is reduced to 1.5X1012m2 / s. The implementation can improve the crack resistance and durability of the prefabricated concrete pile cap unit. A synergetic effect of the mixed ber inhibits dry shrinkage and load crack expansion, the surface treatment enhances a bermatrix interfacial performance, and a mix proportion and a curing technology of the optimized concrete further improve the compactness and impermeability. Through testing, after the pile cap unit is exposed to salt spray environment for 5 years, a number of surface cracks is reduced by 40%, and a corrosion area rate of the steel bar is 33%, thus meeting a longterm service requirement of a marine wharf. According to another embodiment of the present invention, the pile cap unit may have a length of 6.0 m, 7.0 m or 8.0 m and a width of 4.0 m, 4.5 m or 5.0 m, and a specic dimension may be determined according to a load demand of the wharf. A galvanized steel connecting plate with a thickness of 12 mm, 13 mm or 15 mm may be pre-embedded in the joint between adjacent pile cap units, and the connecting plate may be made of a Q345B steel plate, and a thickness of a surface galvanized layer is 280 um. A high-strength bolt may adopt an M24 specication (performance grade 10.9), and a pre-tightening force of the bolt during transverse connection is set to be 350 kN-400 kN. The connecting plate is xed in the embedding groove at an end portion of the pile cap unit by welding or bolting, and a groove opening position is 50 mm away from an edge of the pile cap. When the pile cap unit is prefabricated, a connecting plate positioning slot is preset in a formwork, and the connecting plate and the pile cap form a whole afterconcrete pouring. During mounting, the adjacent pile cap units are aligned, and then the highstrength bolts are inserted and tightened in two stages to a design torque by a hydraulic wrench. A distance between bolt holes may be set to be 150 mm, a hole diameter is 26 mm, and an allowable deviation is i0.5 mm. The galvanized steel plate may be purchased from a Baosteel BZJ 345B model, and the bolt may be a Gemyear GY10.9 grade product. According to a static load test (GB / T 50152), a shear strength of the joint of the pile cap unit is 215 MPa, and fatigue life of a bolted joint (JTJ 215) meets a load requirement of 2 million cycles. This design improves connection reliability of the pile cap unit by 20%-25% and mounting efciency of the pile cap unit by 30%. The prestressed concrete pipe pile has an external diameter of 800 mm, 900 mm or 1000 mm and a wall thickness of 120 mm-150 mm, and a concrete strength grade of a pile body is C80. A diameter of the reserved pile hole in the bottom portion of the pile cap unit may be 120 mm, 125 mm or 130 mm, and a center deviation of the pile hole is 35 mm. Underwater nondispersible concrete may be C45 grade, which has a slump degree of 180220 mm, and is added with a UWBII dispersion inhibitor (l.2%-l.5%). The anchoring steel bar may be an HRB400 grade rebar, which has a diameter of 25 mm and an exposed length of 300 mm, 325 mm or 350 mm, and a verticality deviation of the exposed section is 32°. When the pipe pile is mounted, the pile top is embedded in the pile hole in the pile cap, and the anchoring steel bar is inserted into the concrete of the pile hole at an insertion depth of2200 mm. The concrete in the pile hole is poured by a conduit method at a pouring speed controlled at 0.5-0.8 m3 / h, and cured for 7 days after pouring. The pipe pile may be a Jianhua PHG800 prestressed pipe pile, and the underwater concrete may be purchased from a Zoomlion C45-UWB series. The anchoring steel bar may adopt an Ansteel HRB400E-25 specication. According to a pull-off test (GB / T 50205), a bonding strength between the anchoring steel bar and the concrete is 28 MPa, and a 28-day compressive strength of the concrete of the pile hole is 250 MPa. This design improves an uplift bearing capacity of connection between the pile foundation and the pile cap by 15%-20%, and reduces a construction error rate to be within 3%. A cross section height of the trapezoidal steel rail may be 80 mm, 90 mm or 100 mm, a width of a rail head is 60 mm, a width of a rail bottom is 120 mm, and the trapezoidal steel rail may be made of Q235B galvanized steel. The depth of the Tshaped embedding groove is 30%, 33% or 35% of the thickness of the module, and a width of the groove opening is matched with the cross section of the steel rail, with a tolerance of il mm. The anti-falling pin may be a 304 stainless steel pin with a diameter of 16 mm, 18 mm or 20 mm, a surface of the pin is galvanized, a length of the pin is 150 mm-l80 mm, and shear resistance of the pin is 250 kN. The embedding groove in the back surface of the fender module is processed by a CNC milling machine at a processing accuracy of :|:0.2 mm. When the fender module is mounted, the Tshaped embedding groove horizontally slides in the design position, the pin hole is aligned and then the anti-falling pin is inserted into the pin hole, and antiloosening nuts (model GB / T 6175) are mounted at two ends of the pin. The steel rail is embedded in a center line of the side surface of the pile cap unit, and a gap between the fender module and the steel rail is 32 mm. The stainless steel pin may be purchased from a Zhenghong ZH-304-16 model, and the CNC milling machine may be a Shenyang Machine Tool VMC850E model. According to an impact test (JT / T 4), a tensile strength of a joint between the fender module and the steel rail is 212 kN, and a safety factor of shear resistance of the anti-falling pin is 22.5. Replacement time of the module is shortened by 40%-50% compared with a traditional welding method. This design reduces a displacement of the fender system by 30%-35% under the impact of ship berthing. According to another embodiment of the present invention, the concrete matrix adopts P0 42.5 Portland cement, such as 42.5 grade ordinary Portland cement produced by Conch Cement. The coarse aggregate may be the continuously graded granite gravel of 5-10 mm, which has a crushing value of 512% and a silt content of 30.5%, such as granite gravel produced in Ningde, Fujian. The ne aggregate may be the river sand with the neness modulus of 2.6-2.9, such as medium sand in the middle and lower reaches of the Yangtze River, which has a silt content of 31.0%. The water-binder ratio is set to be 0.32-0.35, such as 0.33 or 0.34. The grade II y ash (such as Class F grade II y ash of Huaneng Power Plant) and the silica fume (such as Elkem micro-silica powder 920U) are doped into the cementing material, the content of the y ash is 15-20% (such as 18%) and the content of the silica fume is 58% (such as 6%) based on the total mass of the cementing material. An adding order of the raw materials is the cement, the y ash, the silica fume, the ne aggregate and the coarse aggregate, and mixing water is added after dry mixing for 30 seconds. The concrete is stirred by the forced doublehorizontal-shaft mixer (such as a JSlSOO model), stirring time is 290 seconds, and a discharging temperature is controlled at 10-30°C. The coarse aggregate is premixed with the ne aggregate and the cementing material in the mixer, added with water, and then stirred evenly. A slump degree of the mixture is controlled at 120-150 mm, such as 130 mm, which is realized by adjusting a water reducing agent (such as a polycarboxylic acid water reducing agent, with a content of 0.81.2%). Layered distribution is adopted during pouring, a thickness of each layer is 3400 mm, and the layer is compacted by Vibration through an internal Vibrator (such as a ZN50 model) at a Vibration distance of 3400mm, thus avoiding aggregate segregation. After pouring, the surface is covered with a plastic lm to prevent water evaporation. The steam curing is carried out in a programmable steam curing kiln (such as a YATAI Heavy Industry ZYK-40 model), wherein a heating rate is 515°C / h, a temperature in a constant-temperature stage is 4045°C (such as 42°C), a humidity is 290% and constant-temperature time is 24-36 hours (such as 30 hours). A cooling rate is 520°C / h, and after cooling to an ambient temperature difference of 520°C, the operation is ended. During natural curing, a geotextile is covered after removing the formwork, water is sprayed regularly to keep the surface moist, and a curing period is 28 days. In the curing period, ambient temperature and humidity are recorded daily, and if the ambient temperature is lower than 5°C, the components are wrapped with an electric blanket and covered with thermal insulation cotton. After curing, the concrete has a 28day compressive strength of 250 MPa and a chloride ion permeability coefcient of 34.0X 1012 mz / s. By accurately controlling the proportion of the concrete, the aggregate gradation and the curing conditions, the compactness and impermeability of the pile cap unit can be improved. The continuously graded aggregate reduces a porosity, and the y ash and the silica fume optimize a cementing system, thus reducing hydration heat. The steam curing accelerates early strength development, and the natural curing ensures later strength stability. The nal concrete has high chloride ion penetration resistance and sulfate corrosion resistance, thus being suitable for longterm effects of dry-wet cycle and salt spray corrosion in marine environment. According to another embodiment of the present invention, the polyurea waterproof coating adopts twocomponent spraying equipment (such as a Graco H-XP3 model), wherein a component A is an aliphatic isocyanate prepolymer (such as Wanhua Chemical WANNATE® 6215, with an NCO content of 19%), a component B is an amino-terminated polyether (such as BASF JEFFAMINE® T5000, with a molecular weight of 2500), and the components are mixed according to a ratio of 1: 1. A spraying thickness of the bottom layer is 08-12 mm, such as 1.0 mm, and the top layer is sprayed to a total thickness of 2.0-2.5 mm, such as 2.3 mm. A base surface is pretreated by a sand blasting machine (such as a BLACKCOW Q326 model) until a roughness degree reaches Sa2.5 grade. Within 4 hours after sand blasting, the base surface is cleaned by an industrial vacuum cleaner (such as Karcher NT 35 / 1), and it is detected by a hygrometer that a water content of the base surface is 53%. If the water content exceeds the standard, a heat gun (such as Bosch GHG 660) may be used for local drying. Before spraying, the base surface is preheated by an infrared radiation heater (such as Saikesi IR-2000), and a preheating temperature is 58°C higher than an ambient temperature, for example, the base surface is preheated to 25-28°C when the ambient temperature is 20°C. The temperature of the base surface is dynamically maintained at 15-35°C, and when the ambient temperature is lower than 15°C, power of the heater is set to be 35 kW; and when the ambient temperature is higher than 35°C, an atomized water curtain machine (such as Noba NBS-50) is used for cooling, wherein a particle size of water mist is 5 50 um. When the bottom layer is sprayed, the pressure is set to be 18-20 MPa, such as 19 MPa, and the moving speed of the spray gun is 0.70.8 m / s, such as 0.75 m / s; and the pressure of the top layer is increased to 2122 MPa, such as 21.5 MPa, and the moving speed of the spray gun is reduced to 0.5-0.6 m / s, and such as 0.55 m / s. The spray gun (such as Graco GX-21) is kept vertical to the base surface, a spraying distance is 300-350 mm, such as 325 mm, a swing amplitude of the spray gun is 550 mm, and an overlapping width of adjacent spraying belts is 1 / 3-1 / 2 of a spraying swath width, for example, when the spraying swath width is 200 mm, the overlapping width is 70100 mm. A surface temperature of the coating is monitored by an infrared thermometer (such as Fluke TiS75) within 30 minutes after spraying, a heating rate is 35°C / min, and a peak temperature is 360°C, such as 55°C. During curing, it is monitored by a temperature and humidity recorder (such as Testo 174H) that an environmental relative humidity is 375%. If the humidity exceeds the standard, a dehumidier (such as Panasonic F-YZJ90) may be started. After curing, an adhesive force of the coating is tested by a grid method (ASTM D3359), and a required grade is 24B; and a CS-lO grinding wheel is used in an abrasion resistance test (ASTM D4060), and a mass loss after 1000 cycles is 350 mg. A defective region needs to be polished to the Sa2.5 grade before supplementary spraying, and a supplementary spraying thickness is consistent with the original coating. By accurately controlling the spraying parameters, the base surface treatment and the curing conditions, the polyurea coating may be ensured to be uniform and compact, without pinhole or sag defects. Layered spraying enhances the directional arrangement of the nano-ller and improves the surface wear resistance; and strict temperature and humidity control reduces bubbles and the risk of peeling. The nal coating has high adhesive force, ultraviolet resistance and seawater erosion resistance, effectively blocks chloride ion penetration, and prolongs service life of the wharf structure in marine environment. According to another embodiment of the present invention, the silane anticorrosive agent may be a two-component composite silane, which contains isobutyl triethoxysilane accounting for 60%, 65% or 70% by mass and octyl trimethoxysilane accounting for 40%, 35% or 30 by mass, and a total content of the silane anticorrosive agent is 0.8%, 1.0% or 1.2% of the total mass of the cementing material. An impregnation technology may adopt a vacuum pressure impregnation method, an impregnation pressure may be set to be 0.5 MPa, 0.6 MPa or 0.8 MPa, and impregnation time may be 2 hours, 2.5 hours or 3 hours. Impregnation equipment may be an industrialgrade impregnation machine with a vacuum pump and a pressure tank, and after impregnation, normal-temperature curing time is 48 hours. The coarse aggregate of the pile body concrete may be the granite gravel with the particle size of 10-20 mm, the ne aggregate of the pile body concrete may be the river sand with the neness modulus of 2.3-2.6, the waterbinder ratio may be set to be 0.28, 0.30 or 0.32, and the cementing material may be doped with 8%, 10% or 12% slag powder and 5%, 6% or 8% metakaolin. After silane treatment, a surface water absorption rate of the pile body concrete may be controlled at 50.01 mm / minl / Z, a chloride ion migration coefcient of the pile body concrete may be controlled at 33.0X1012m2 / s, and a sulfate corrosion resistance grade may reach K8150. A water absorption test may refer to an ASTM C1585 standard, a chloride ion migration coefcient test may refer to an NT BUILD 492 method, and a sulfate corrosion resistance test may refer to GB / T 500822009. The coarse aggregate of the pile body concrete may be granite produced in Fujian, the ne aggregate of the pile body concrete may be river sand in the middle and lower reaches of the Yangtze River, the slag powder may be S95 grade superne slag powder, and the metakaolin may be calcined kaolin, with a specific surface area of 215000 mZ / kg. The transitional sealing belt may be arranged at the junction between the epoxy resin coating and the silane treatment layer of the anchoring steel bar in the pile top, and the sealing belt may be made of a silane modied polyurethane colloid, which has a width set to be 15 mm, 18 mm or 20 mm and a thickness set to be 1.0 mm, 1.2 mm or 1.5 mm. The sealing belt may be continuously covered at a junction between the steel bar and the concrete, a manual glue injection gun or automatic glue application equipment is used during construction, and curing time of glue is controlled within 2-4 hours. The silane modied polyurethane colloid of the sealing belt may be a two-component product, wherein a component A contains an isocyanate group, a component B contains a hydroxyl polyether, and a mixing volume ratio of the components is 1: 1. Before coating, a surface of the junction needs to be sandblasted to a cleanliness degree of Sa2.5 grade, and wiped with absolute alcohol to remove oil stains. Through the two-component ratio of the silane corrosion inhibitor and the vacuum impregnation technology, the chloride ion penetration resistance and the sulfate corrosion resistance of the pile body concrete are signicantly improved. By doping the concrete with the slag powder and the metakaolin, the compactness of the concrete is optimized, and in combination with silane treatment, the water absorption rate and the chloride ion migration coefcient are strictly controlled. The continuous coverage with the transitional sealing belt effectively blocks a corrosive medium from invading a steel barconcrete interface, thus prolonging the service life of the pile foundation in marine environment. According to another embodiment of the present invention, the silane anti-corrosive agent is composed of the isobutyl triethoxysilane and the octyl trimethoxysilane in a mass ratio of 60%70%: 30%40%, and the total content of the silane anticorrosive agent is 0.8%1.2% of the total mass of the cementing material. Specically, a mass ratio of the isobutyl triethoxysilane may be 65%, and a mass ratio of the octyl trimethoxysilane is 35%; and the total content of the silane anti-corrosive agent may be set to be 1.0%. The silane corrosion inhibitor is injected into the pile body concrete by a vacuum pressure impregnation method, wherein an impregnation pressure may be 0.6 MPa or 0.7 MPa, and impregnation time may be 2.5 hours, and the pile body concrete is cured at normal temperature for 48 hours after impregnation. Commercially available vacuum pressure impregnation equipment (such as a VPI-200 model) may be used, be selected, which has a pressure adjustment range of 0.5-1.0 MPa. During impregnation, the pile body concrete needs to be placed in a sealed chamber, and after vacuumizing to -0.08 MPa, a silane mixed solution is injected, and the pressure is increased to a set value and then maintained for a certain time. An ambient temperature of curing may be controlled at 20-25°C, and a humidity is 570%. The coarse aggregate of the pile body concrete is the granite gravel with the particle size of 10-20 mm, the ne aggregate of the pile body concrete is the river sand with the neness modulus of 2.3-2.6, and the water-binder ratio is 0.28-0.32. In the admixture, the content of the slag powder is 10% of the total mass of the cementing material, and the content of the metakaolin is 6% of the total mass of the cementing material. The granite gravel may be granite produced in Nanping, Fujian, and the river sand may be natural river sand in the middle and lower reaches of the Yangtze River. The slag powder may be S95 grade slag micropowder, and the metakaolin may be calcined kaolin (A1203 content 240%). When the concrete is stirred, the coarse aggregate, the ne aggregate and the admixture are added into the forced mixer (such as a J S750 model) in proportion for dry mixing for 1 minute, and then added with cement and water in a volume corresponding to the water-binder ratio for even stirring for 3 minutes. After silane treatment, the surface water absorption rate of the pile body concrete is 30.01 mm / minl / Z, the chloride ion migration coefcient of the pile body concrete is 53.0><1012 m2 / s, and the sulfate corrosion resistance grade is 2KS150. The transitional sealing belt is arranged at the junction between the epoxy resin coating and the silane treatment layer of the anchoring steel bar in the pile top, the sealing belt may have a width of 18 mm and a thickness of 1.2 mm, and is formed by the continuous coating of the silane modied polyurethane colloid (such as SIKA®-4120). During construction, the sealing belt material is evenly coated on the junction by the glue injection gun, and after curing, a seamless waterproof barrier is formed. In a performance test, the surface water absorption rate is tested according to GB / T 50082-2009, the chloride ion migration coefcient is determined by an ASTM C1202 method, and a sulfate corrosion resistance test is carried out according to a KS F 2711 standard. Through the above embodiment, corrosion resistance of the pile body concrete is signicantly improved, a silane penetration depth is uniform, a chloride ion penetration path is effectively blocked, and an interfacial sealing performance is further enhanced by the transitional sealing belt, thus prolonging the service life of the pile foundation in marine environment. According to another embodiment of the present invention, the polyurea waterproof coating is composed of two components. The component A is the isocyanate prepolymer, wherein the NCO content may be 18%, 19% or 20%, and is added with 0.5%, 0.8% or 1.0% benzotriazole ultraviolet absorber (such as BASF Tinuvin 328) by mass.The component B is the amino-terminated polyether, wherein the molecular weight may be 2000, 2300 or 2500, and is added with 20%, 25% or 30% nano-alumina wearresistant ller by mass (with a particle size of 50 nm, 65 nm or 80 nm, and 0.3%, 0.4% or 0.5% silane coupling agent by mass (such as Evonik Dynasylan AMMO). The components A and B are mixed according to the volume ratio of l: 1, mixing equipment may be a Graco H-XP3 twocomponent spraying machine, and a ratio error is controlled within i2%. The NCO content of the component A is determined by a chemical titration method, a content of the ultraviolet absorber is determined by an accelerated aging test, and the target is that a yellowing index of the coating is AE33 after ultraviolet irradiation for 1000 hours. The nano-alumina ller may be purchased from Bayer Company (Bayoxide Alu C model) of Germany, and the silane coupling agent is premixed with the component B through a high-speed disperser (such as Netzsch Disperrnat), wherein a rotating speed is set to be 1200 rpm, and dispersing time is 20 minutes. An experimental object is a steel plate substrate spraying test piece, and a test method refers to Test Methods for Building Waterproong Coatings (GB / T 16777-2008). The coating is sprayed in two stages, the thickness of the bottom layer may be 0.8 mm, 1.0 mm or 1.2 mm, and after an interval of 10 minutes, 12 minutes or 15 minutes, the top layer is sprayed to the total thickness of 2.0mm, 2.3 mm or 2.5mm. The spraying equipment may be a Gusmer CSM3000 polyurea spraying machine, a spray gun is a GX-7 model, a spraying distance is set to be 300 mm, 320 mm or 350 mm, and a moving speed of the spray gun may be 0.5 m / s, 0.6 m / s or 0.8 m / s. A spraying pressure of the bottom layer is set to be 18 MPa, 19 MPa or 20 MPa, a spraying pressure of the top layer is increased to 21 MPa, 21.5 MPa or 22 MPa, a swing range of the spray gun is 350 mm, and an overlapping width of adjacent spraying belts is 1 / 3 or 1 / 2 of a spraying swath width. The parameters are set according to the microscopic observation of the cross section of the coating, and the target is that there is no bubble and no sag and the ller is directionally arranged. The pre-treatment of the base surface comprises sandblasting the base surface to the roughness degree of Sa2.5 grade (by an Ingersoll Rand Blastrac 1-8DP sand-blasting machine), and cleaning and dehumidifying the base surface within 4 hours after sandblasting (a water content is 33%). An ambient temperature of construction is controlled at 15°C, 25°C or 35°C, when the temperature is lower than 15°C, the base surface is preheated to 2023°C by an infrared heater (such as Thermor HT300), and when the temperature is higher than 35°C, the base surface is cooled by an atomized water curtain. After spraying, a surface temperature of the coating is monitored within 30 minutes, a heating rate is controlled at 3°C / min, 4°C / min or 5°C / min, and a peak temperature is 360°C (such as monitoring in real time by a Fluke Ti400 infrared thermal imager). During curing, an ambient humidity is controlled at 50%, 60% or 70% (a humidity sensor is a Honeywell HIH4000 model), and when the humidity exceeds the limit, a dehumidier (such as Deye DYD-D20A) is started. After the coating is cured, an adhesive force is tested by a pulloff method, and a target value is 25 MPa (referring to Paints and Vamishes - Pull-off Test for Adhesion GB / T 5210-2006). A Taber abrader (5135 model) is used in a wear resistance test, wherein a load is 1 kg, and a mass loss after 1000 revolutions is 550 mg. A functional test shows that the optimized coating has no bubble within 500 hours in a salt spray test (ASTM B117), and a gloss retention rate is 280% after articial climate aging (GB / T 1865) for 2000 hours. The directional arrangement of the nano-alumina ller improves the wear resistance by 30%-40%, and the silane coupling agent improves an interfacial bonding strength between the coating and the base surface. The implementation can improve the weatherability, wear resistance and construction reliability of the polyurea waterproof coating. The two-component ratio and the technological control reduce coating defects, the nanoller and the directional spraying technology enhance the surface hardness, and the dynamic control of temperature and humidity avoids poor curing. By testing, after the coating is in service for 10 years in marine wharf environment, an integrity rate of the waterproof layer is 295%, there is no peeling phenomenon in an anchorage zone, and a chloride ion permeability is 50.01 g / mZ-d, thus meeting a requirement of longterm protection. According to another embodiment of the present invention, in the ber reinforced concrete of the prefabricated concrete pile cap unit, the ber volume content may be 1.2%, 1.5% or 1.8%. The endhook steel ber and the polypropylene reticular ber may be mixed in the concrete, wherein the length of the steel ber is 1215 mm, and the length of the polypropylene ber is 18-22 mm. The cross section height of the trapezoidal steel rail may be set to be 80 mm, 90 mm or 100 mm, and the steel rail is pre-embedded in the side surface of the pile cap unit 200 mm away from the top surface, with a longitudinal distance of 1.5 m. The steel rail may be made of Q345B steel, a surface of the steel rail is subjected to hot-dip galvanization, and a thickness of a galvanized layer is not less than 80 um. During concrete pouring, an HZSl20 mixing station may be used for mixing, and stirring time is 120-150 seconds. The steel rail is positioned by a total station (such as Leica TSl6), and xed in a steel formwork by a special xture. After concrete pouring, the pile cap unit is cured in steam environment at 40-45°C for 24-36 hours, and then naturally cured for a period of 28 days. After removing the formwork, the rust prevention of the trapezoidal steel rail reserved on the side surface of the pile cap unit needs to be inspected, so as to ensure that there is no crack or coating peeling on the surface. In the construction process, the uniformity of the ber and the concrete is controlled through the stirring time, and a positioning accuracy error of the steel rail needs to be less than 2 mm. This design can improve the crack resistance of the pile cap unit, reduce the local damage caused by transportation or hoisting, and provide a stable sliding track for the fender module. In the epoxy mortar lled in the joint between adjacent pile cap units, the length of the chopped basalt ber may be 12 mm, 13 mm or 15 mm, the ber diameter is 7-9 um, and the surface of the chopped basalt ber is treated with the silane coupling agent. The hydrophobic nano-silica may be a modied material with a particle size of 10-20 nm and a specic surface area of 180-220 m2 / g, and the content of the nano-silica is 3%, 4% or 5% of the total mass of the cementing material. The thickness of the polyurea waterproof coating may be controlled at 2.0 mm, 2.3 mm or 2.5 mm, and the coating is sprayed in two stages, wherein the thickness of the bottom layer is 0.8-1.2 mm, and the top layer is supplemented to the total thickness. The epoxy mortar may be stirred by a forced mixer (such as Sany Heavy Industry J S500), and a stirring order is that the basalt ber is added and dispersed for 58 minutes rst, and then the nano-silica is added to continuously stir for 35 minutes. The polyurea is sprayed by a Graco Reactor E-XP2 spraying machine, and the pre-treatment of the base surface comprises sandblasting to the roughness degree of Sa2.5 grade, and the water content is controlled below 3%. After joint lling, the epoxy mortar needs to be cured at 15-30°C for 24 hours, and then the polyurea coating is constructed, wherein the spraying pressure is 18-22 MPa, and the moving speed of the spray gun is 0.5-0.8 m / s. The polyurea coating on the surface of the joint needs to cover the joint and extend to two sides for 100 mm, so as to form a continuous waterproof barrier. In this technology, through ber reinforcement and hydrophobic modication of nano-material, the chloride ion permeability is signicantly reduced, and meanwhile, the weatherability of the polyurea coating may resist ultraviolet light and mechanical wear, thus prolonging sealing life of the joint. In the pile body concrete of the composite pile foundation assembly, the content of the silane corrosion inhibitor may be 0.8%, 1.0% or 1.2%, and the silane corrosion inhibitor is compounded by isobutyl triethoxysilane (60-70%) and octyl trimethoxysilane (3040%). The thickness of the epoxy resin layer coated on the surface of the anchoring steel bar is 150-200 um, and the exposed length of the steel bar may be set to be 300 mm, 320 mm or 350 mm. The anchoring steer bar in the pile top is the HRB400 grade rebar with the diameter of 25-28 mm, and a verticality deviation during preembedding is less than 1%. The silane impregnation treatment may be completed by vacuum pressure impregnation equipment (such as Qingdao Hi-tech HTK-VPI-300) at an impregnation pressure of 0.50.8 MPa for 23 hours. An SATAjet 5000 spray gun is used in the construction of the epoxy resin coating, and before spraying, the steel bar needs to be sandblasted and derusted to Sa2.5 grade. The coarse aggregate of the pile body concrete is the granite gravel (with a particle size of 10-20 mm), the water-binder ratio is 028-032, and the chloride ion migration coefcient after curing needs to be 53.0X1012 m2 / s. After the anchoring steel bar in the pile top is inserted into the pile hole in the pile cap unit, C45 underwater non-dispersible concrete is poured into the hole, and an anchoring depth is not less than 250 mm. A synergistic effect of silane treatment and epoxy coating may block a chloride ion invasion path, and the transitional sealing belt (the silane modied polyurethane colloid) at the pile top can further prevent interfacial corrosion, thus improving the durability of the pile foundation in marine environment. In the threelayer composite structure of the elastic fender module, a thickness of the outer layer of polyurethane is 8-10 mm, a density of the middle layer of closed-cell rubber foam is 300-400 kg / m3, and a thickness of the inner layer of butyl rubber is 5-8 mm. The depth of the Tshaped embedding groove is 1 / 3 of the thickness of the module, for example, when the thickness of the module is 150 mm, the depth of the embedding groove is 50 mm, and when the thickness of the module is 210 mm, the depth of the embedding groove is 70 mm. A horizontal alignment error between the center line of the embedding groove in the back surface of the module and the trapezoidal steel rail needs to be less than 3 mm. A composite elastomer may be formed by vulcanization through a at vulcanizing machine (such as Qingdao DoubleStar QLB50T) at a vulcanization temperature of 150-160°C and a vulcanization pressure of 10-15 MPa for 30-40 minutes. The Tshaped embedding groove is processed by the CNC milling machine, and the width of the groove is matched with the cross section of the steel rail, with the tolerance of 0.5 mm. When the fender module is mounted, the module is allowed to slide in place along the steel rail through hoisting equipment, and then the anti-falling pins with the diameter of 16 mm are inserted to x the module, wherein the distance between the pin holes is 200250 mm. The three-layer structure of the module is bonded by vulcanization to form a whole, wherein the outer layer of weather-resistant polyurethane resists ultraviolet aging, the middle foam absorbs impact energy, and the inner layer of high-damping butyl rubber reduces vibration transmission. The sliding connection design between the T-shaped embedding groove and the steel rail facilitates later maintenance and replacement, and avoids stress concentration in a bolt hole position, thus reducing the risk of concrete cracking. The ber reinforced concrete is combined with multiple anti-corrosion measures, which signicantly prolongs the service life of the wharf in marine environment. The prefabricated unit and the modular fender reduce wet construction on site, which shortens the construction period by about 20%-30%. The three-layer composite structure of the elastic fender gives consideration to energy absorption efciency and durability, thus adapting to berthing needs of ships with different tonnages. Although the implementation of the present invention has been disclosed above, it is not limited to the applications listed in the specication and the embodiments, and can be fully applied to various elds suitable for the present invention, and additional modications can be easily implemented by those skilled in the art. Therefore, the present invention is not limited to the specic details and illustrations shown and described herein without departing from the general concept dened by the claims and the equivalent scope.

Claims

1. Fabricated quay structure, comprising: a precast concrete pile cap unit, a composite pile foundation assembly and an elastic fender module, where the precast concrete pile cap unit is formed by casting a fiber reinforced concrete with a fiber volume content of 1.2% - 1.8%, and a trapezoidal steel rail is pre-embedded into a side surface of the pile cap unit; with a seam between the prefabricated concrete pile cap units are filled with epoxy mortar, and a polyurea waterproof coating is applied to a surface of the hardened epoxy mortar, which a coating thickness is 2.0 – 2.5 mm; where the composite pile foundation assembly is a prestressed concrete pipe pile, in which a pile body concrete is doped with a silane corrosion inhibitor, with a content of the silane corrosion inhibitor is 0.8% - 1.2% of a total mass, where a anchor steel bar is pre-embedded in a pile top, and where a surface of the anchoring steel bar is covered with an epoxy resin layer; and where the elastic fender module is made of closed cell rubber and a polyurethane composite elastomer, wherein a rear surface of the module is provided with a T-shaped embedding groove, where the depth of the embedding groove is 1 / 3 of the thickness of the module is, and where the T-shaped embedding groove is connected to the trapezoidal steel rail; where the closed cell rubber and the polyurethane composite elastomer of the elastic fender module uses a three-layer composite structure, where an outer layer is a weather resistant polyurethane layer, a middle layer is a closed cell rubber foam, and a inner layer is a butyl rubber layer with high damping; the three layers are vulcanized are bonded to form a whole; where a chopped basalt fiber and a hydrophobic nano-silica is added to the epoxy mortar, with the chopped basalt fiber a length of 12 - 15 mm and a fiber diameter of 7 - 9 um, with a surface area of the fiber is treated with a silane coupling agent, and a proportion of the fiber 1.5 - 2.0 kg / m3; and where the hydrophobic nano-silica has a particle size of 10 - 20 nm and a specific surface area of ​​180 - 220 m2 / g, with a nano-silica content of 3 - 5% of the total mass, where the nano-silica is hydrophobically modified with methyltrimethoxysilane, and wherein the modifier content is 1.5 - 2.0% of a mass of the nano silica is.

2. Fabricated quay structure according to claim 1, characterised in that a matrix of the epoxy mortar is formed by mixing bisphenol A epoxy resin and a polyamide curing agent at a mass ratio of 2:1, and 30 - 40% quartz sand aggregate by mass is added to the resin matrix, which provides a total has aggregate particle size of 0.1 - 0.3 mm; and during production, when the epoxy mortar is stirred, the fiber is added and dispersed for 5-8 minutes, then the nano-silica is added to stir continuously for 3 - 5 minutes, controlling the curing temperature at 15 - 30°C, and where the curing humidity is S 70%.

3. Fabricated quay structure according to claim 1, characterised in that a single pile cap unit has a length of 6 - 8 m and a width of 4 - 5 m, in which a steel connection plate with a galvanized coating is pre-embedded in a seam between the adjacent pile cap units, and where the connection plate has a thickness of 12 - 15 mm and is cross-connected by a high-strength M24 bolt; an outer diameter of the pipe pile is 800 – 1000 mm; When the precast concrete pile cap unit is installed, a post hole with a diameter of 120mm is reserved in a bottom part, where C45 is underwater non-dispersible concrete is poured into the pile hole, with the anchoring steel bar of the composite pile foundation assembly is inserted into the concrete of the pile hole, and where an exposed length of the anchoring steel bar is 300 350 mm; and the elastic fender module is embedded with the trapezoidal steel rail which is pre-embedded into the side surface of the pile cap unit by the T-shaped embedment groove, whereby a cross-sectional height of the steel rail is 80 - 100 mm, and an anti-falling pin with a diameter of 16 mm is used for penetration and fixation after embedding.

4. Fabricated quay structure according to claim 1, characterised in that in the fiber reinforced concrete of the precast concrete pile cap unit the fiber a mixed composite fiber is, comprising an end hook steel fiber with a length of 12 - 15 mm, which has a diameter of 0.2 0.25 mm and a length-to-diameter ratio of 60 75, and a polypropylene net-shaped fibre with a length of 18 - 22 mm, which has an equivalent diameter of 0.02 - 0.04 mm and a length-to-diameter ratio of 450 - 550, whereby a The volume content of the steel fiber is 0.8%-1.0%, and the volume content of the polypropylene fiber 0.4% - 0.8% is; and a surface of the steel fiber is treated with a zinc phosphate anticorrosive coating, which has a coating thickness of 35 um, and the polypropylene fiber is subjected plasma etching to form a rough surface at the micron level.

5. Fabricated quay structure according to claim 4, characterised in that the concrete matrix uses P°O 42.5 Portland cement, with a coarse aggregate a continuously graded crushed stone of 5 - 10 mm, with a fine aggregate as a medium sand has a fineness modulus of 2.6 - 2.9, with a water-binder ratio 0.32 - 0.35, and where 15 - 20% fly ash of class 11 and 5 - 8% silica fume on a total mass of a cementing material is doped; and After pouring, the concrete is cured by steam at 40 - 45°C for 24 - 36 hours and then naturally cured for a period of 28 days.

6. Fabricated quay structure according to claim 5, characterized in that the polyurea waterproof coating is a two-component reaction coating, which is formed by mixing of an isocyanate component A and an amino resin component B according to a volume ratio from 1:1 and by spraying the mixture, where component A is an aliphatic isocyanate prepolymer contains 18 - 20% NCO and 0.5 - 1.0% benzotriazole ultraviolet absorber by mass, and component B contains an amino-terminated polyether with a molecular weight of 2000 - 2500, 20 - 30% nano-alumina wear resistant filler by mass with a particle size of 50 - 80 nm, and 0.3 - 0.5% silane coupling agent by mass.

7. Fabricated quay structure according to claim 6, characterised in that the coating is sprayed in two phases, with a spray thickness of a base layer 0.8 - 1.2 mm, and after an interval of 10 - 15 minutes a top layer is formed to a total thickness of 2.0 – 2.5 mm is sprayed; during spraying, a base surface temperature of 15 35°C is maintained controlled, where the spray pressure is 18 - 22 MPa, and where the moving speed is a spray gun is 0.5 - 0.8 m / s; in the pretreatment of the base surface: after the epoxy mortar has hardened, the surface sandblasted to a roughness grade of Sa2.5 grade, where the base surface cleaned and dehumidified within 4 hours after sandblasting, and where the water content of the base surface is 5 3%; in the temperature gradient control: the base surface is preheated before the spraying, where a preheating temperature is 5 - 8°C higher than a ambient temperature, where the base surface temperature is dynamically maintained within a range of 15-35°C, where as the ambient temperature is lower than 15°C, an infrared radiant heater is used for compensation, and when the If the ambient temperature is higher than 35°C, an atomized water curtain is used for cooling; in the phased pressure adjustment: when the bottom layer is sprayed, the pressure set to 18 - 20 MPa, with the moving speed of the spray gun being 0.7 - 0.8 m / s and a continuous thin layer is formed; and when the top layer is sprayed, the pressure is increased to 21 - 22 MPa, with the moving speed of the spray gun being reduced to 0.5 - 0.6 m / s, and involving the directional arrangement of a nano-alumina filler is being improved; in trajectory optimization: the spray gun vertical to the base surface is maintained, with a spraying distance of 300 - 350 mm, whereby a the spray gun oscillation amplitude S is 50 mm, and where an overlapping width of adjacent spray belts amounts to 1 / 3 - 1 / 2 of a spray swath width; and in the curing monitoring: a surface temperature of the coating is measured within 30 minutes after spraying, with a heating rate controlled at 5 SOC / min, where the peak temperature S is 60°C, and the relative humidity during the hardening S 75% is.

8. Fabricated quay structure according to claim 1, characterized in that the silane anticorrosive agent doped in the pile body concrete of the composite pile foundation assembly is a two component composite silane, which is isobutyl triethoxysilane which comprises 60-70% by mass and octyl trimethoxysilane which comprises 30-40% by mass mass uuit, with a total content of the silane anti-corrosive agent 0.8% - 1.2% of the total mass of the cementing material.

9. Fabricated quay structure according to claim 8, characterised in that the silane anticorrosive agent by a vacuum pressure impregnation method in the pile body concrete is injected, with an impregnation pressure of 0.5 - 0.8 MPa, whereby an impregnation time of 2 3 hours, where the concrete is left for 48 hours after impregnation normal temperature is hardened; a coarse aggregate of the pile body concrete a granite gravel has a particle size of 10 - 20 mm, and a fine aggregate of the pile body concrete is a river sand with a fineness modulus of 2.3 - 2.6, where a water-binder ratio is 0.28 - 0.32, and 8 - 12% slag powder and 5 - 8% metakaolin are doped based on the total mass of the cementing material; and after silane treatment, a surface water absorption rate of the pile body concrete S 0.01 mm / min / 2 is, a chloride ion migration coefficient is 5 3081012 mz / s, and a sulphate corrosion resistance class Z KS 1 50 is; and a transition seal belt is applied to a junction between the epoxy resin coating and the silane treatment layer of the anchoring steel bar in the pile top, with the sealing belt is made of a silane-modified polyurethane colloid, which has a width of 15 - 20 mm and has a thickness of 1.0 - 1.5 mm, and is formed by continuous coating.

10. Construction method for the fabricated quay structure, comprising the following steps: forming the precast concrete pile cap unit by pouring the fibre reinforced concrete with a fibre volume content of 1.2% - 1.8%, and pre-embedding of the trapezoidal steel rail in the side surface of the stack GLB unit; filling the epoxy mortar in the seam between the adjacent prefabricated concrete pile cap units, adding the chopped basalt fiber with the length of 12 15 mm and with the diameter of 7 - 9 um and of the hydrophobic nano-silica in the epoxy mortar, treating the surface of the chopped basalt fiber with the silane coupling agent, where the fiber content is 1.5 - 2.0 kg / m3, the hydrophobic nano-silica being the particle size of 10 - 20 nm and specific surface area of ​​180 - 220 m2 / g, whereby a content of the nano-silica is 3 - 5% of the total mass, and the hydrophobic modification of the nanosilica with the methyltrimethoxysilane, where the modifier content is 1.5-2.0% of a mass of the nano-silica is; applying the polyurea waterproof coating to the surface of the seam after the epoxy mortar is hardened, and the coating thickness is controlled at 2.0 - 2.5 mm; when preparing the composite pile foundation assembly, dipping the silane corrosion inhibitor in the pile body concrete of the prestressed concrete pipe pile, whereby the content of the silane corrosion inhibitor 0.8% - 1.2% of the total mass of the cementing material is the pre-embedding of the anchoring steel bar in the pile top, and the coating the surface of the anchoring steel bar with the epoxy resin layer; when preparing the elastic fender module, making the three-layer composite structure with the closed cell rubber and the polyurethane composite elastomer, where an outer layer is a weather-resistant polyurethane layer, a middle layer is a closed cell rubber foam, and an inner layer is a high-dampening butyl rubber layer; the bonding of the three layers by vulcanization to form a whole, and processing the T-shaped embedding groove with the depth of 1 / 3 of the module thickness on the back surface of the module; and embedding the T-shaped groove of the elastic fender module with the Trapezoidal steel rail on the side surface of the precast concrete pile cap.