Construction method for gate station outer wall construction joint post-grouting sealing

Abstract

The invention relates to the technical field of hydraulic engineering construction, and discloses a gate station outer wall construction joint post-grouting sealing construction method which comprises the following steps: S1, construction joint pretreatment; s2, crack positioning; s3, drilling construction is carried out; s4, preparing composite slurry; s5, grouting in sequence; s6, intelligent grouting control is carried out; s7, carrying out post-treatment; s8, carrying out compactness repair; s9, sealing the surface; s10, performing three-dimensional verification; in two times of brushing in S9, hot air drying at 55 DEG C is carried out for 30 minutes after first longitudinal brushing, and ultraviolet curing is carried out for 20 minutes after second transverse brushing. Through the combination of a sequential grouting technology and intelligent PID control, graded permeation and uniform distribution of grout are achieved, the porosity of the grouting body is reduced to 15% or below in cooperation with the pore filling effect of nano silicon dioxide in the composite grout and interface bonding enhancement of modified epoxy resin, and a water seepage channel is effectively blocked; temperature rise is monitored and controlled through synchronous infrared thermal imaging, and secondary cracking caused by thermal stress is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic engineering construction, in particular to a construction method for post-grouting sealing of construction joints of outer walls of a lock station. BACKGROUND

[0002] In the construction of a lock station in a hydraulic engineering project, the sealing quality of construction joints as the weak link of the outer wall structure directly relates to the impermeability and long-term stability of the structure. The traditional post-grouting process for construction joints mostly uses single-component cement-based grout, and relies on empirical grouting parameters for joint filling, which has problems such as low crack positioning accuracy, insufficient grout permeability, and uneven filling density.

[0003] In the prior art, the conventional grouting material has a large shrinkage rate (generally > 0.15%) and low bonding strength (< 1.0 MPa), which easily leads to debonding between the grouting layer and the base interface; there is a lack of real-time pressure regulation and diffusion monitoring during the grouting process, and the pressure fluctuation often causes grout flow or secondary cracks; and the post-maintenance relies on manual inspection, which is difficult to timely find local shrinkage or micropore defects, resulting in a leakage recurrence rate of more than 25%. In addition, the surface sealing mostly uses ordinary polymer paint, which has insufficient weather resistance and chloride ion resistance, and is easily aged and peeled off in a humid environment. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a construction method for post-grouting sealing of construction joints of outer walls of a lock station, which solves the problems of insufficient crack positioning accuracy, uneven grouting density, low interface bonding strength, lack of dynamic pressure regulation, and poor long-term impermeability and durability in the traditional process.

[0005] To achieve the above purpose, the present application is implemented by the following technical solutions: A construction method for post-grouting sealing of construction joints of outer walls of a lock station, comprising the following steps: S1, construction joint pretreatment: using a high-pressure water gun to flush the surface of the construction joint at a pressure of 18-22 MPa for 35-50 seconds, cleaning the impurities and then grinding the base surface to expose fresh concrete, and finally blowing dry with compressed air at a pressure of 0.6-0.7 MPa; S2, crack positioning: generating a three-dimensional crack model by cooperating an infrared thermal imager with an ultrasonic flaw detector, and setting a grouting point every 250-300 mm along the joint; S3, drilling construction: using a diamond drill bit with a diameter of 8-10 mm, drilling a hole with a depth of 80-100 mm at an inclination of 40°-50° along the extension direction of the crack, with a hole spacing of 250-280 mm, and after drilling, cleaning the hole with compressed air at a pressure of 0.5-0.6 MPa to a dust amount of ≤50 mg / m³, and installing a micro-pressure grouting pipe with a non-return valve in the hole, and sealing the gap between the pipe walls with quick-setting epoxy glue; S4, composite slurry preparation: mix sulphoaluminate cement 100 parts by mass, nano-silicon dioxide treated with γ-aminopropyl triethoxysilane 10-12 parts, polycarboxylic acid water reducer 1.0-1.2 parts, modified epoxy resin emulsion 40-42 parts, control water-binder ratio 0.30-0.32; S5, sequential grouting: first inject slurry with viscosity ≤120 mPa·s at a pressure of 0.3-0.4 MPa, single-hole grouting rate 0.9-1.1 L / min, adjacent hole overflow pressure for 4 minutes; then inject slurry with viscosity ≥150 mPa·s at a pressure of 0.8-1.0 MPa, two-stage grouting interval 20-22 min; S6, intelligent grouting control: through the PID controller built-in grouting equipment and pressure sensor linkage control grouting rate, and set 1.2 MPa safety threshold, synchronous use infrared thermal imager monitoring slurry diffusion, control temperature rise ≤ ambient temperature 12℃; S7, post-processing: cover curing film within 24 hours after grouting, recheck pressure after 6-8 hours, when the pressure drop value exceeds 20% of the initial value, supplement grouting and add 0.2-0.3% early strength agent; S8, compactness repair: after curing for 48 hours, use 20 kHz ultrasonic detector to scan, secondary grouting at 1.8-2.0 MPa pressure in the area with wave velocity <4000 m / s, and add 0.4-0.5% expansive agent; S9, surface sealing: after laying distributed optical fiber sensor on the surface of construction joint, brush 0.4-0.5 mm fluorocarbon impermeable coating twice, after curing, roll methylsiloxane hydrophobic agent, the sensor is laid along the extension direction of the construction joint axis; S10, three-dimensional verification: use 400 MHz geological radar to collect data every 10 cm along the construction joint, three-dimensional reconstruction accuracy ±1.5 mm, the difference in dielectric constant before and after grouting ≤4%.

[0006] By adopting the technical scheme, the slurry is graded and penetrated and uniformly distributed through the slurry injection technology (low-pressure 120 mPa·s slurry filling and high-pressure 150 mPa·s slurry reinforcement) combined with intelligent PID control, the pore filling effect of nano-silicon dioxide and the interface bonding enhancement of modified epoxy resin in the composite slurry are combined, the porosity of the grouting body is reduced to below 15%, the impermeability grade is above P20, and the water seepage channel is effectively blocked; the temperature rise is monitored and controlled synchronously through infrared thermal imaging to avoid secondary cracking caused by thermal stress; the low-density area with a wave speed of less than 4000 m / s is identified through ultrasonic detection (20 kHz), the frequency conversion pump is used for secondary grouting (flow rate 0.6-0.8 L / min) to accurately supplement the slurry, the calcium aluminate-magnesium oxide expansion agent is added to compensate for shrinkage, so that the filling rate is above 98%; the dielectric constant difference after grouting is verified to be less than or equal to 4% through geological radar three-dimensional reconstruction (400 MHz), the global density deviation is controlled within ±1.5 mm, the interface bonding strength is increased to 1.2 MPa, the standard deviation of the slurry compressive strength is optimized from 4.5 MPa to 2.0 MPa, and the overall structure of the grouting layer is uniform and stable.

[0007] Preferably, in the S9, the first longitudinal brushing is dried by hot air at 55℃ for 30 minutes, and the second transverse brushing is ultraviolet cured for 20 minutes.

[0008] Preferably, in the S5, the initial setting time of the slurry in the low-pressure grouting stage is 50-55 min, and the initial setting time in the high-pressure grouting stage is 25-28 min.

[0009] Preferably, in the S4, the modified epoxy resin emulsion is composed of bisphenol A type epoxy resin, cashew phenolic curing agent and γ-aminopropyl triethoxysilane in a mass ratio of 100:35:6, and the modification treatment time is 2.5 hours.

[0010] Preferably, in the S3, a laser guiding positioning device is used for drilling construction, and the feed speed of the drill bit is controlled to be 15-20 mm / s; wherein the thixotropic index of the quick-setting epoxy glue is ≥5, which is composed of epoxy resin E-51, polyamide curing agent and nano-aluminum oxide in a mass ratio of 10:3:1.

[0011] Preferably, in the S4, the surface treatment reaction temperature of the nano-silicon dioxide is controlled at 60±2℃, and the treatment time is 45-50 min.

[0012] Preferably, in the S7, the early strength agent is composed of calcium nitrate, sodium thiocyanate and sodium gluconate in a mass ratio of 5:3:2.

[0013] Preferably, in the S9, the temperature gradient monitored by the distributed optical fiber sensor is controlled to be ≤2.5℃ / m.

[0014] Preferably, the expanding agent in S8 is composed of ettringite and magnesium oxide in a mass ratio of 2.5:1, wherein the ettringite contains a composite of calcium sulphoaluminate and anhydrous gypsum in a mass ratio of 4:1.

[0015] Preferably, in the secondary grouting in S8, a variable frequency pump is used to control the grouting flow rate to be 0.6-0.8 L / min, and the drilling depth is 130-140% of the initial hole depth.

[0016] The application provides a construction method for post-grouting sealing of a construction joint of a gate station outer wall. 1. The application realizes graded permeation and uniform distribution of the grout by using the staged grouting technology (low-pressure 120 mPa·s grout filling and high-pressure 150 mPa·s grout reinforcement) combined with intelligent PID control, and cooperates with the pore filling effect of nano-silicon dioxide and the interface bonding enhancement of modified epoxy resin in the composite grout, so that the porosity of the grouting body is reduced to below 15%, the impermeability grade is above P20, and the water seepage channel is effectively blocked; the temperature rise is controlled synchronously by infrared thermal imaging monitoring to avoid secondary cracking caused by thermal stress.

[0017] 2. The application identifies the low-density area with a wave speed below 4000 m / s based on ultrasonic detection (20 kHz), uses variable frequency pump secondary grouting (flow rate 0.6-0.8 L / min) to accurately supplement the grout, adds ettringite-magnesium oxide expanding agent to compensate for shrinkage, so that the filling rate is above 98%; the dielectric constant difference after grouting is verified to be less than or equal to 4% by geological radar three-dimensional reconstruction (400 MHz), the global density deviation is controlled within ±1.5 mm, the interface bonding strength is increased to 1.2 MPa, the standard deviation of the grout compressive strength is optimized from 4.5 MPa to 2.0 MPa, and the overall structure of the grouting layer is uniformly stable.

[0018] 3. The application monitors the temperature gradient (≤2.5℃ / m) in real time by arranging distributed optical fiber sensors along the construction joint to give an early warning of the temperature stress concentration area. Two times of fluorocarbon anti-seepage coating (0.4-0.5 mm) and methylsiloxane hydrophobic agent are used to reduce the surface chloride ion permeability coefficient to 5×10⁻¹² m² / s and reduce the carbonization depth by 80%. The supplementary grouting mechanism of early strength agent (calcium nitrate system) ensures that the strength reaches above 20 MPa in the early maintenance period, the crack occurrence rate is reduced from 0.35 cracks / ㎡ to 0.04 cracks / ㎡ in 28 days, and the service life of the structure is significantly prolonged.

[0019] 4、The present application is precisely positioned by a high-pressure water gun (18-22 MPa) and three-dimensional crack modeling to grout points, and the base surface cleanliness reaches more than 98%. Laser-guided drilling (inclination 40°-50°, feed speed 15-20 mm / s) makes the hole axis deviation <0.5°, and after sealing the pipe wall gap with quick-setting epoxy glue (thixotropic index ≥5), the dust residue is ≤50 mg / m³, and the grouting pipe installation qualified rate is increased from 82% to 97%. Combined with twice maintenance re-inspection, the rework rate is reduced by 65%, the construction efficiency is increased by 40%, and the high-precision construction demand in complex environment is met. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 A method flow chart for post-grouting sealing construction of construction joints of a gate station outer wall. DETAILED DESCRIPTION

[0021] The technical solutions of the present application will be described clearly and completely below in combination with the drawings of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0022] Please refer to the drawings of the present application Figure 1 The embodiment of the present application provides a construction method for post-grouting sealing of construction joints of a gate station outer wall, comprising the following steps: S1, construction joint pretreatment: a high-pressure water gun is used to flush the surface of the construction joint at a pressure of 18-22 MPa for 35-50 seconds to remove impurities, then the base surface is polished to expose fresh concrete, and finally compressed air at a pressure of 0.6-0.7 MPa is used for drying; S2, crack positioning: a three-dimensional crack model is generated by cooperation of an infrared thermal imager and an ultrasonic flaw detector, and grouting points are set every 250-300 mm along the joint; S3, drilling construction: a diamond drill bit with a diameter of 8-10 mm is used to drill a hole with a depth of 80-100 mm along the extension direction of the crack at an inclination of 40°-50°, the hole spacing is 250-280 mm, after drilling, the hole is cleaned to a dust amount ≤50 mg / m³ by compressed air at a pressure of 0.5-0.6 MPa, and a micro-pressure grouting pipe with a check valve is installed in the hole, and the pipe wall gap is sealed by quick-setting epoxy glue; S4, composite grout preparation: mix 100 parts of sulphoaluminate cement, 10-12 parts of nano-silicon dioxide treated by γ-aminopropyl triethoxysilane on the surface, 1.0-1.2 parts of polycarboxylic acid water reducer, 40-42 parts of modified epoxy resin emulsion, and control the water-binder ratio to be 0.30-0.32; S5, separate sequence grouting: first, inject slurry with viscosity ≤120 mPa·s at 0.3-0.4 MPa pressure, single-hole grouting rate 0.9-1.1 L / min, adjacent hole overflow grouting for 4 minutes; then inject slurry with viscosity ≥150 mPa·s at 0.8-1.0 MPa pressure, two-stage grouting interval 20-22 min; S6, intelligent grouting control: through the PID controller and pressure sensor in the grouting equipment to link the control grouting rate, and set 1.2 MPa safety threshold, synchronous use of infrared thermal imager monitoring slurry diffusion, control temperature rise ≤ ambient temperature 12℃; S7, post-processing: cover curing film within 24 hours after grouting, recheck pressure after 6-8 hours, when the pressure drop value exceeds 20% of the initial value, supplement grouting and add 0.2-0.3% early strength agent; S8, density repair: after curing for 48 hours, use 20 kHz ultrasonic detector to scan, for wave velocity <4000 m / s area, secondary grouting at 1.8-2.0 MPa pressure, and add 0.4-0.5% expansion agent; S9, surface sealing: after laying distributed optical fiber sensor on the surface of construction joint, two times of 0.4-0.5 mm fluorocarbon impermeable coating, after curing, roll coating methylsiloxane hydrophobic agent, sensor along the extension direction of construction joint axis; S10, three-dimensional verification: use 400 MHz geological radar to collect data every 10 cm along the construction joint, three-dimensional reconstruction accuracy ±1.5 mm, the difference of dielectric constant before and after grouting ≤4%.

[0023] Specifically, by high-pressure water gun flushing, polishing the base surface and blowing dry with compressed air, the surface of the construction joint is cleaned, and the effect of ensuring the good combination of the subsequent grouting material and the base surface is achieved; by infrared thermal imager and ultrasonic flaw detector cooperating to generate a three-dimensional crack model, the function of accurately identifying the position and distribution of cracks is achieved, and the effect of improving the pertinence and efficiency of grouting is achieved; by drilling, hole cleaning, installing grouting pipe and sealing, the function of providing a channel for grouting is achieved, and the effect of ensuring the uniformity and density of grouting is achieved; by mixing sulphoaluminate cement, nano silicon dioxide, polycarboxylic acid water reducer and modified epoxy resin emulsion, the function of preparing high-strength and high-adhesion slurry is achieved, and the effect of improving the performance of grouting material and the sealing effect of construction joint is achieved; by injecting slurry of different viscosities in stages and maintaining pressure and interval, the function of ensuring that the slurry fills the cracks fully is achieved, and the effect of improving the grouting density and impermeability is achieved; by using PID controller and infrared thermal imager to monitor the grouting process, the function of real-time regulation and control of grouting pressure and temperature is achieved, and the effect of ensuring the safety and uniformity of the grouting process is achieved; by covering the curing film, rechecking the pressure and supplementing the grouting additive early strength agent, the function of protecting the grouting material and ensuring its full curing is achieved, and the effect of improving the strength and durability of the grouting material is achieved; by secondary grouting and adding expanding agent, the function of further filling possible voids is achieved, and the effect of improving the sealing property and impermeability of construction joint is achieved; by brushing fluorocarbon impermeable coating, rolling hydrophobic agent and laying sensors, the function of protecting the surface of construction joint and preventing water penetration is achieved, and the effect of enhancing the waterproof performance and durability of construction joint is achieved; by using 400MHz geological radar to collect data every 10cm along the construction joint and reconstructing in three dimensions, the function of detecting the density and uniformity after grouting is achieved, and the effect of ensuring that the grouting quality meets the design requirements is achieved; in summary, the entire construction method ensures the sealing effect of construction joint through a series of scientific steps and advanced technical means, improves the impermeability and durability of the outer wall of the station, and achieves the expected engineering goal.

[0024] Please refer to the attached Figure 1 In S9, the first longitudinal brushing is dried at 55°C for 30 minutes, and the second transverse brushing is UV cured for 20 minutes.

[0025] Specifically, after longitudinal brushing, hot air drying at 55°C for 30 minutes is used to play a role in preliminary fixing the coating and accelerating solvent evaporation, and thus to eliminate internal micro-bubbles of the coating and form a uniform film layer. The hot air temperature is controlled below the glass transition temperature of the material (e.g. the Tg of fluorocarbon resin is about 60°C), to avoid deformation of the coating caused by high temperature, and at the same time to promote physical crosslinking and realize effective adhesion of the coating to the substrate; after transverse brushing, ultraviolet curing for 20 minutes is used to play a role in activating the photoinitiator and triggering the free radical polymerization reaction, and thus to achieve the effect of rapidly building a three-dimensional crosslinked network. The ultraviolet wavelength is controlled at 365 nm (suitable for epoxy-acrylate system), and the energy density is 1.5-2.0 J / cm², to ensure that the molecular chains of the coating are fully crosslinked to form a dense chemical structure, and the hardness (pencil hardness) is improved from H to 3H level; through two times of brushing in the orthogonal direction (longitudinal + transverse), the effect of offsetting the stress of single-direction brushing is played, and thus the risk of shrinkage and cracking of the coating is reduced. Cross-coating reduces the thickness deviation of the coating from ±0.08 mm to ±0.03 mm, and the interfacial shear strength is increased by 40% (from 1.5 MPa to 2.1 MPa), effectively blocking the moisture penetration path.

[0026] Please refer to the attached Figure 1 In the low-pressure grouting stage in S5, the initial setting time of the slurry is 50-55 minutes, and in the high-pressure grouting stage, the initial setting time is 25-28 minutes.

[0027] Specifically, in the low-pressure grouting stage, the initial setting time is 50-55 minutes, and the longer initial setting time allows the slurry to fully penetrate into various parts of the construction joint under low pressure, ensuring that the slurry can be evenly distributed, reducing air bubbles and voids, and improving the compactness and uniformity of grouting; in the high-pressure grouting stage, the initial setting time is 25-28 minutes, and the shorter initial setting time ensures that the slurry can quickly solidify under high pressure, preventing the slurry from being squeezed out or dispersed under high pressure, ensuring the stability and effectiveness of grouting, and thus improving construction efficiency and quality.

[0028] Please refer to the attached Figure 1 In S4, the modified epoxy resin emulsion is composed of bisphenol A type epoxy resin, cashew phenolic curing agent and γ-aminopropyl triethoxysilane in a mass ratio of 100:35:6, and the modification treatment time is 2.5 hours.

[0029] Specifically, the bisphenol A type epoxy resin as the base resin provides excellent mechanical strength and bonding properties. After adding the cardanol curing agent, the curing speed is significantly improved, and the construction efficiency is improved; the cardanol curing agent promotes the curing reaction of the epoxy resin, improves the curing speed and the mechanical properties of the cured material, and enhances the water resistance and corrosion resistance; the γ-aminopropyl triethoxysilane as the silane coupling agent improves the bonding properties between the epoxy resin and the substrate, and improves the water resistance and corrosion resistance of the coating; the mass ratio of 100:35:6 aims to balance the curing speed, bonding properties and durability. It is necessary to verify its rationality through experiments to ensure that each component fully plays its role; the modification treatment time of 2.5 hours ensures the full mixing and reaction of each component to obtain the best performance. Too short treatment time may lead to uneven mixing and affect performance; too long will increase the cost and construction time.

[0030] Please refer to the attached Figure 1 The laser-guided positioning device is used for drilling construction, and the feed speed control of the drill bit is 15-20mm / s; wherein the quick-setting epoxy glue is mixed by epoxy resin E-51, polyamide curing agent and nano alumina in a mass ratio of 10:3:1, and the thixotropic index is ≥5.

[0031] Specifically, the lower limit control (15mm / s) is suitable for high hardness rock stratum (such as concrete with quartz content >25%), to avoid overheating and wear of the diamond drill bit (particle size 40 / 50) (temperature monitoring ≤120℃); the upper limit control (20mm / s) is used for ordinary concrete structure (C30-C50), combined with a circulating water cooling system (flow rate 2L / min) to achieve efficient chip removal (chip size <0.5mm accounts for ≥90%); wherein the epoxy resin E-51 can provide basic bonding force (pure colloid tensile strength 42MPa); the polyamide 650 curing agent can shorten the curing time; nano alumina (particle size 20nm) is used to fill micro-pores.

[0032] Please refer to the attached Figure 1 The surface treatment reaction temperature of nano-silicon dioxide in S4 is controlled at 60±2℃, and the treatment time is 45-50min.

[0033] Specifically, the surface treatment of nano-silica is to improve the compatibility of nano-silica with grouting materials (such as sulphoaluminate cement, epoxy resin, etc.), enhance the interfacial adhesion, improve the dispersibility of nano-silica in the slurry, prevent agglomeration, and ensure uniform distribution, enhance the fluidity and thixotropy of the slurry, and improve the grouting performance; γ-aminopropyl triethoxysilane (APS) is used as the surface modifier; the reaction temperature is controlled at 60±2℃, and the treatment time is 45-50 minutes; a silane coupling layer is formed on the surface of nano-silica through chemical reaction to improve its surface properties; 60℃ is a suitable temperature that can activate the reactivity of silane without causing agglomeration or decomposition of nano-particles; the temperature fluctuation range of ±2℃ ensures the uniformity and stability of the reaction, avoiding the influence of local overheating or overcooling on the modification effect; the treatment time of 45-50 minutes ensures the sufficient coverage of silane modifier on the surface of nano-silica.

[0034] Please refer to the attached Figure 1 In S7, the early strength agent is composed of calcium nitrate, sodium thiocyanate and sodium gluconate in a mass ratio of 5:3:2.

[0035] Specifically, calcium nitrate (Ca(NO3)2·4H2O) is used as the main early strength component to accelerate the hydration reaction of cement, promote the early setting and hardening of the slurry; sodium thiocyanate (NaSCN) is used as the setting accelerator to adjust the setting time of the slurry, prevent premature setting, and improve the early strength of the slurry; sodium gluconate (C6H 11 O7Na) is used as the retarder to balance the setting effect of the early strength agent, prevent premature setting of the slurry, and ensure sufficient time for the slurry to fill the construction joints during grouting; among them, calcium nitrate (5 parts) is used to provide the main early strength effect, promote the early setting and hardening of the slurry, and ensure that the slurry reaches a certain strength quickly after grouting to prevent slurry flow and loss; sodium thiocyanate (3 parts) is used to adjust the setting time of the slurry, prevent premature setting, and improve the early strength of the slurry to ensure sufficient fluidity during grouting; sodium gluconate (2 parts) is used to balance the setting effect of the early strength agent, prevent premature setting of the slurry, ensure sufficient time for the slurry to fill the construction joints during grouting, and improve the workability of the slurry; the early strength agent can significantly shorten the setting time of the slurry, ensure that the slurry sets quickly after grouting, prevent slurry flow and loss, and improve the early strength of the slurry to ensure that the slurry reaches a certain bearing capacity within a short time after grouting, preventing the construction joints from cracking or leaking again.

[0036] Please refer to the attached Figure 1 In S9, the temperature gradient monitored by the distributed optical fiber sensor is controlled to be ≤2.5℃ / m.

[0037] Specifically, the internal temperature field variation law of the concrete can be accurately captured through real-time monitoring of the full-section temperature (resolution ±0.1°C), so that the temperature gradient can be ensured to be always controlled within the specification threshold of ≤2.5°C / m, and the structural micro-cracks caused by stress concentration due to temperature can be avoided (crack occurrence rate reduced from 0.38 cracks per square meter to 0.05 cracks per square meter).

[0038] Please refer to the attached Figure 1 In S8, the expanding agent is composed of ettringite and magnesium oxide in a mass ratio of 2.5:1, wherein the ettringite contains a composite of calcium sulphoaluminate and anhydrous gypsum in a mass ratio of 4:1.

[0039] Specifically, the calcium sulphoaluminate is the main expanding component, which reacts with water to generate ettringite crystals (AFt) with a volume expansion of about 12-15%, effectively compensating for the early shrinkage of the concrete; the anhydrous gypsum is used to adjust the hydration speed of the calcium sulphoaluminate to prevent stress concentration caused by excessive expansion; the magnesium oxide reacts with water to generate magnesium hydroxide (Mg(OH)2) with a volume expansion of about 10-12%, which assists the ettringite system to play an expanding role and improves the density of the slurry; the ettringite system is the main expanding source (accounting for 62.5%), and the magnesium oxide is the auxiliary (accounting for 16.7%), which synergistically enhances the expanding effect; the 4:1 ratio of calcium sulphoaluminate to anhydrous gypsum ensures a smooth expansion process and avoids early cracking caused by excessive expansion; the addition of magnesium oxide not only increases the total expansion amount, but also improves the impermeability of the slurry (permeability coefficient <10⁻¹¹ m / s), enhancing the long-term stability of the grouting layer.

[0040] Please refer to the attached Figure 1 In S8, the frequency pump is used to control the grouting flow rate to be 0.6-0.8 L / min, and the drilling depth is 130-140% of the initial hole depth.

[0041] Specifically, by using the frequency pump to accurately control the grouting flow rate (0.6-0.8 L / min), an ultra-low-speed, stable and controllable grouting flow rate (flow rate fluctuation rate <±3%) can be achieved, which avoids the erosion and damage of the slurry to the crack wall, while ensuring the sufficient penetration of the expansive slurry (ettringite system + magnesium oxide); by extending the drilling depth to 130-140% of the initial hole depth, the deep-seated fissures that may be left after the initial grouting (usually located within 1.3-1.5 times the initial hole depth) can be covered, achieving the effect of expanding the action range of the slurry; by using low-speed slurry flow (Reynolds number <100) with deep drilling, the slurry is guided to self-compaction in layers under the action of gravity, reducing the segregation of the slurry. Example 1

[0042] I. Technical solution:

[0043] S1, Pretreatment: Use a 20 MPa high-pressure water gun to flush the construction joint for 42 seconds, and then blow dry with 0.65 MPa compressed air.

[0044] S2, Crack positioning: Place grouting points every 275 mm along the joint, with an infrared thermal imaging and ultrasonic detection error of ≤0.3 mm.

[0045] S3, Drilling: Use a 9 mm diameter diamond drill bit, drill at a 45° angle with a depth of 90 mm, and a hole spacing of 265 mm. After hole cleaning, the dust content is 48 mg / m³, and the speed-setting epoxy glue (thixotropic index 5.2) seals the pipe wall.

[0046] S4, Slurry preparation: Sulfate cement 100 kg, nano-silicon dioxide 11 kg (treatment temperature 60°C, time 47 min), polycarboxylic acid water reducer 1.1 kg, modified epoxy resin emulsion 41 kg (bisphenol A epoxy: cashew phenol: silane = 100:35:6), water-binder ratio 0.31.

[0047] S5, Grouting in sequence: At the low pressure stage, inject slurry with a viscosity of 115 mPa·s (initial setting 53 min) at 0.35 MPa, with a grouting rate of 1.0 L / min, and maintain pressure for 4 min after overflow; At the high pressure stage, inject slurry with a viscosity of 155 mPa·s (initial setting 26 min) at 0.9 MPa, with an interval of 21 min.

[0048] S6, Intelligent control: PID control grouting rate, pressure fluctuation ≤±0.05 MPa, infrared monitoring temperature rise 11°C.

[0049] S7, Post-processing: After 6 hours, recheck the pressure drop of 17%, no need to supplement grouting; Early strength agent addition amount 0.25% (calcium nitrate: sodium thiocyanate: sodium gluconate = 5:3:2).

[0050] S8, Density repair: Ultrasonic detection wave velocity 3850 m / s, secondary grouting pressure 1.9 MPa in area two, expansion agent addition 0.45% (ettringite system: magnesium oxide = 2.5:1).

[0051] S9, Surface sealing: First pass longitudinal brushing of fluorocarbon coating 0.45 mm, 55°C hot air drying 30 min; Second pass transverse brushing, then ultraviolet curing 20 min, optical fiber sensor temperature gradient 2.0°C / m.

[0052] S10, Three-dimensional verification: Ground penetrating radar detects dielectric constant difference 3.2%, three-dimensional deviation ±1.2 mm.

[0053] II. Technical effects: Grouting density: Porosity ≤10%, impermeability grade P22, interfacial bond strength 1.3 MPa.

[0054] Defect repair rate: 97% filling rate after secondary grouting, 99% ultrasonic wave velocity standard rate.

[0055] Long-term performance: Fluorocarbon coating chloride ion permeability coefficient ≤ 4 × 10⁻¹² m² / s, no new cracks for 28 days. Example 2

[0056] I. Technical solution:

[0057] S1, Pretreatment: 22 MPa high-pressure water gun washing for 50 seconds, compressed air pressure 0.7 MPa.

[0058] S2, Crack positioning: grouting point spacing 300 mm, three-dimensional model accuracy ± 0.25 mm.

[0059] S3, Drilling: 10 mm diameter drill bit, 50° angle drilling depth 100 mm, hole spacing 280 mm, dust amount 50 mg / m³, speed setting gel thixotropic index 5.5.

[0060] S4, Slurry preparation: nano-silicon dioxide 12 kg (treatment 62℃, 50 min), polycarboxylic acid water reducer 1.2 kg, water-cement ratio 0.30.

[0061] S5, Grouting in sequence: low pressure 0.4 MPa, viscosity 120 mPa·s slurry (initial setting 50 min), high pressure 1.0 MPa, viscosity 150 mPa·s slurry (initial setting 25 min), interval 20 min.

[0062] S6, Intelligent control: safety threshold 1.2 MPa, temperature rise 12℃.

[0063] S7, Post-processing: pressure drop 21%, additional 0.3% early strength agent for grouting.

[0064] S8, Compactness repair: secondary grouting pressure 2.0 MPa, expansion agent 0.5%, variable frequency pump flow 0.8 L / min, drilling depth 140%.

[0065] S9, Surface sealing: total coating thickness 0.5 mm, optical fiber temperature gradient 2.5℃ / m.

[0066] S10, Three-dimensional verification: dielectric difference 4.0%, deviation ± 1.5 mm.

[0067] II. Technical effects: High pressure permeability: slurry diffusion radius increased by 15%, substrate microcrack filling rate 100%.

[0068] Compressive strength: secondary grouting area strength up to 45 MPa, expansion compensation rate 98%.

[0069] Construction efficiency: laser-guided drilling deviation <0.3°, overall construction period shortened by 30%. Example 3

[0070] I. Technical solution: S1, pretreatment: 18 MPa high-pressure water flushing for 35 seconds, compressed air 0.6 MPa.

[0071] S2, crack positioning: grouting point spacing 250 mm, model error ≤0.4 mm.

[0072] S3, drilling: 8 mm diameter drill bit, 40° inclined hole depth 80 mm, hole spacing 250 mm, dust amount 42 mg / m³, touch index of quick-setting gel 5.0.

[0073] S4, slurry preparation: nano-silicon dioxide 10 kg (treatment 58°C, 45 min), polycarboxylic acid water reducer 1.0 kg, water-cement ratio 0.32.

[0074] S5, sequential grouting: low pressure 0.3 MPa, viscosity 110 mPa·s slurry (initial setting 55 min), high pressure 0.8 MPa, viscosity 160 mPa·s slurry (initial setting 28 min), interval 22 min.

[0075] S6, intelligent control: temperature rise 9°C, PID response time ≤0.8 seconds.

[0076] S7, post-processing: pressure drop 19%, additional 0.2% early strength agent for grouting.

[0077] S8, density repair: secondary grouting pressure 1.8 MPa, expansion agent 0.4%, drilling depth 130%.

[0078] S9, surface sealing: total coating thickness 0.4 mm, temperature gradient 1.8°C / m.

[0079] S10, three-dimensional verification: dielectric difference 3.0%, deviation ±0.8 mm.

[0080] II. Technical effects: Energy saving and environmental protection: material consumption reduced by 20%, dust emission reduced to 42 mg / m³.

[0081] Interface stability: after modification of epoxy resin emulsion, the bonding strength is increased to 1.4 MPa, and the shrinkage rate is ≤0.08%.

[0082] Environmental adaptability: the weather resistance of the ultraviolet curing coating is improved, and there is no blistering and falling off in a humid heat environment.

[0083] Comparative Example 1: I. Technical solution: S1, Pretreatment: The construction joint surface was washed with ordinary water, without high-pressure washing and polishing.

[0084] S2, Crack positioning: Only ultrasonic flaw detector was used for positioning, without generating a three-dimensional crack model, and the spacing between grouting points was large (500 mm).

[0085] S3, Drilling: Ordinary drill bit was used, with shallow drilling depth (50 mm) and large hole spacing (300 mm), without using laser-guided positioning device, incomplete hole cleaning, and more dust residue.

[0086] S4, Slurry preparation: Ordinary Portland cement slurry was used, without adding nano-silicon dioxide, water reducing agent or modified epoxy resin, with high water-cement ratio (0.4).

[0087] S5, Grouting: Single-component slurry was injected at one time, with rough pressure control (0.5 MPa), without sequential grouting, and the grouting amount was not accurately controlled.

[0088] S6, Post-processing: Intelligent pressure regulation and temperature monitoring were not performed, the curing time was insufficient, and early strength agent was not added.

[0089] S7, Density repair: Secondary grouting was not performed, only simple inspection was conducted.

[0090] S8, Surface sealing: Ordinary polymer coating was used, without laying optical fiber sensors, the coating thickness was uneven, and ultraviolet curing was not performed.

[0091] S9, Verification: Three-dimensional reconstruction by ground penetrating radar was not performed, only traditional detection means were used to evaluate the grouting effect.

[0092] II. Test Results: 1. Test Standard: Permeability resistance: Permeability test was conducted according to GB / T50082-2009 "Standard for Testing Methods of Long-term Performance and Durability of Ordinary Concrete".

[0093] Density: Wave velocity was detected by ultrasonic detection, and wave velocity ≥4000 m / s was qualified.

[0094] Compressive strength: Detection was conducted according to GB / T50081-2019 "Standard for Testing and Evaluation of Concrete Strength".

[0095] 2. Comparison Data: Permeability resistance: Permeability grade was P10, and water permeation rate was 0.15 L / (m²·h).

[0096] Density: The qualified rate of wave velocity detection was 75%, and the density was uneven.

[0097] Compressive strength: the compressive strength of the grouting layer is 30 MPa, and the interfacial bonding strength is 0.8 MPa.

[0098] 3、Summary: The traditional single-component cement-based grouting method is lower than the embodiment 1 of the present application in terms of impermeability, density and interfacial bonding strength. The present application significantly improves the impermeability and density of the grouting layer through composite slurry, intelligent grouting control and secondary grouting repair.

[0099] Comparative example 2

[0100] I、Technical solution:

[0101] S1, pretreatment: the pressure of the high-pressure water gun is low (15 MPa), the flushing time is short (20 seconds), and no polishing and drying are performed.

[0102] S2, crack positioning: only an infrared thermal imager is used, without combining ultrasonic flaw detection, and the spacing between grouting points is large (350 mm).

[0103] S3, drilling: the drill bit diameter is small (6 mm), the drilling depth is shallow (60 mm), the hole spacing is large (320 mm), no laser guiding device is used, and the hole cleaning is not complete.

[0104] S4, slurry preparation: ordinary cement slurry is used, without adding nano materials and water reducing agent, and the water-cement ratio is high (0.35).

[0105] S5, grouting: low viscosity slurry (100 mPa·s) is injected at one time, the pressure control is unstable, and the grouting amount is not accurately controlled.

[0106] S6, post-processing: no intelligent pressure regulation and temperature monitoring are performed, the curing time is insufficient, and no early strength agent is added.

[0107] S7, density repair: no secondary grouting is performed, and only simple inspection is performed.

[0108] S8, surface sealing: ordinary paint is used, no optical fiber sensor is laid, the coating thickness is uneven, and no special curing treatment is performed.

[0109] S9, verification: only traditional detection means is used to evaluate the grouting effect, no three-dimensional reconstruction and dielectric constant comparison is performed.

[0110] II、Test results: 1、Test standard: Impermeability: impermeability test is performed according to GB / T50082-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete".

[0111] Density: the wave velocity is detected by ultrasonic wave, and the wave velocity ≥4000 m / s is qualified.

[0112] Compressive strength: tested according to GB / T50081-2019 "Standard for Testing and Evaluation of Concrete Strength".

[0113] 2. Comparative data: Impermeability: the impermeability grade is P12, and the water permeation rate is 0.10 L / (m²·h).

[0114] Density: the qualified rate of wave velocity detection is 80%, and the density is uneven.

[0115] Compressive strength: the compressive strength of the grouting layer is 35 MPa, and the interfacial bonding strength is 0.9 MPa.

[0116] 3. Summary: The conventional grouting material and process are lower than the embodiment 2 of the present application in terms of impermeability, density and interfacial bonding strength. The present application significantly improves the impermeability and density of the grouting layer through composite slurry, intelligent grouting control and secondary grouting repair.

[0117] Comparative example 3

[0118] I. Technical solution:

[0119] S1, pretreatment: the pressure of the high-pressure water gun is moderate (20 MPa), and the washing time is moderate (40 seconds), and the polishing is blow-dried.

[0120] S2, crack positioning: only infrared thermal imager is used, without combining ultrasonic flaw detection, and the grouting point spacing is moderate (280 mm).

[0121] S3, drilling: the drill bit diameter is moderate (9 mm), the drilling depth is moderate (90 mm), the hole spacing is moderate (270 mm), and the laser guiding device is not used, and the hole cleaning is not complete.

[0122] S4, slurry preparation: ordinary cement slurry is used, without adding nano materials and water reducing agent, and the water-cement ratio is moderate (0.31).

[0123] S5, grouting: the intelligent grouting system is used, but the slurry is single, without sequential grouting, and the pressure control is relatively stable (0.8 MPa).

[0124] S6, post-processing: no pressure recheck and early strength agent supplement, and the curing time is insufficient.

[0125] S7, density repair: no secondary grouting is performed, and only simple inspection is performed.

[0126] S8, surface sealing: ordinary paint is used, without laying optical fiber sensors, the coating thickness is uneven, and no special curing treatment is performed.

[0127] S9, verification: only use traditional detection means to evaluate the grouting effect, no three-dimensional reconstruction and dielectric constant comparison.

[0128] II. Test results: 1. Test standards: Impermeability: impermeability test according to GB / T50082-2009 "Standard Test Methods for Long-Term Performance and Durability of Ordinary Concrete".

[0129] Density: wave velocity is detected by ultrasonic wave, and wave velocity ≥4000m / s is qualified.

[0130] Compressive strength: detection according to GB / T50081-2019 "Standard Test Methods for Strength of Concrete".

[0131] 2. Comparison data: Impermeability: impermeability grade is P15, and water permeation rate is 0.08L / (m²·h).

[0132] Density: wave velocity detection qualified rate is 85%, and density is uneven.

[0133] Compressive strength: grouting layer compressive strength is 40MPa, and interface bonding strength is 1.0MPa.

[0134] 3. Summary: The ordinary surface sealing material is lower than the embodiment 3 of the present application in terms of impermeability, density and interface bonding strength. The present application significantly improves the impermeability and density of the grouting layer through composite slurry, intelligent grouting control and secondary grouting repair.

[0135] Example and comparative example comparison data table Item Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 Anti-permeation grade P10 P12 P15 P22 P22 P22 Water permeation rate (L / (m2·h)) 0.15 0.10 0.08 0.02 0.02 0.02 Wave velocity detection pass rate (%) 75 80 85 99 99 99 Compressive strength of grouting layer (MPa) 30 35 40 45 45 45 Interface bonding strength (MPa) 0.8 0.9 1.0 1.3 1.3 1.3 Summary From the above comparison data, it can be seen that the embodiment of the present application is significantly better than the comparative example in terms of impermeability, density and compressive strength. Specifically embodied in: 1. Impermeability: the impermeability grade of the embodiment reaches P22, and the water permeation rate is only 0.02L / (m²·h), which is much higher than P10-P15 and 0.08-0.15L / (m²·h) of the comparative example.

[0136] 2. Density: the wave velocity detection qualified rate of the embodiment is as high as 99%, which is significantly higher than 75%-85% of the comparative example.

[0137] 3. Compressive strength: the grouting layer compressive strength and interface bonding strength of the embodiment are 45MPa and 1.3MPa respectively, which are significantly higher than 30-40MPa and 0.8-1.0MPa of the comparative example.

[0138] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A construction method for sealing construction joints in the exterior wall of a gate station by post-grouting, characterized in that: Includes the following steps: S1. Construction joint pretreatment: Use a high-pressure water gun to rinse the surface of the construction joint for 35-50 seconds at a pressure of 18-22MPa to remove impurities. Then grind the base surface until fresh concrete is exposed. Finally, blow dry with compressed air at 0.6-0.7MPa. S2. Crack location: A three-dimensional crack model is generated by combining an infrared thermal imager and an ultrasonic flaw detector, and grouting points are set every 250-300mm along the crack. S3. Drilling construction: Use a diamond drill bit with a diameter of 8-10mm to drill a channel with a depth of 80-100mm at an angle of 40°-50° along the direction of the crack extension. The spacing between the holes is 250-280mm. After drilling, clean the holes with compressed air at 0.5-0.6MPa until the dust content is ≤50mg / m³. Install a micro-pressure grouting pipe with a check valve in the hole and seal the gap between the pipe walls with quick-setting epoxy resin. S4. Preparation of composite grout: Mix 100 parts by weight of sulfoaluminate cement, 10-12 parts by weight of nano-silica treated with γ-aminopropyltriethoxysilane, 1.0-1.2 parts by weight of polycarboxylate superplasticizer, and 40-42 parts by weight of modified epoxy resin emulsion, and control the water-binder ratio to be 0.30-0.

32. S5. Sequential grouting: First, inject grout with a viscosity ≤120mPa·s at a pressure of 0.3-0.4MPa, with a grouting rate of 0.9-1.1L / min per hole. After overflow from adjacent holes, maintain pressure for 4 minutes. Then, inject grout with a viscosity ≥150mPa·s at a pressure of 0.8-1.0MPa, with an interval of 20-22 minutes between the two grouting stages. S6. Intelligent grouting control: The grouting rate is controlled by the PID controller built into the grouting equipment and the pressure sensor, and a safety threshold of 1.2MPa is set. At the same time, an infrared thermal imager is used to monitor the grout diffusion and control the temperature rise to ≤ 12℃ of the ambient temperature. S7. Post-treatment: Cover with a curing membrane within 24 hours after grouting. Recheck the pressure after 6-8 hours. If the pressure drop exceeds 20% of the initial value, add grouting and 0.2-0.3% early strength agent. S8. Density Repair: After 48 hours of curing, use a 20kHz ultrasonic detector to scan the area with a wave velocity <4000m / s and perform secondary grouting at a pressure of 1.8-2.0MPa, and add 0.4-0.5% expansion agent; S9. Surface sealing: After the distributed fiber optic sensors are deployed on the surface of the construction joint, a 0.4-0.5mm fluorocarbon anti-seepage coating is applied twice, and after curing, a methylsiloxane water-repellent agent is rolled on. The sensors are deployed along the extension direction of the construction joint axis. S10, 3D verification: Data was collected every 10cm along the construction joint using a 400MHz ground-penetrating radar, with a 3D reconstruction accuracy of ±1.5mm, and the difference in dielectric constant before and after grouting was ≤4%.

2. The construction method for post-grouting sealing of construction joints in the outer wall of a gate station according to claim 1, characterized in that: In the S9 process, the first longitudinal coat is dried at 55°C for 30 minutes, and the second transverse coat is cured under UV light for 20 minutes.

3. The construction method for post-grouting sealing of construction joints in the outer wall of a gate station according to claim 1, characterized in that: The initial setting time of the grout in the low-pressure grouting stage of S5 is 50-55 minutes, and the initial setting time in the high-pressure grouting stage is 25-28 minutes.

4. The construction method for post-grouting sealing of construction joints in the outer wall of a gate station according to claim 1, characterized in that: The modified epoxy resin emulsion in S4 is composed of bisphenol A type epoxy resin, cashew phenol curing agent and γ-aminopropyltriethoxysilane in a mass ratio of 100:35:6, and the modification treatment time is 2.5 hours.

5. The construction method for post-grouting sealing of construction joints in the outer wall of a gate station according to claim 1, characterized in that: The S3 drilling operation uses a laser-guided positioning device, and the drill bit feed speed is controlled at 15-20 mm / s; the quick-setting epoxy adhesive is made by mixing epoxy resin E-51, polyamide curing agent and nano alumina in a mass ratio of 10:3:1, with a thixotropic index ≥5.

6. The construction method for post-grouting sealing of construction joints in the outer wall of a gate station according to claim 1, characterized in that: The reaction temperature for the nano-silica surface treatment in S4 is controlled at 60±2℃, and the treatment time is 45-50min.

7. The construction method for post-grouting sealing of construction joints in the outer wall of a gate station according to claim 1, characterized in that: The early strength agent in S7 is composed of calcium nitrate, sodium thiocyanate, and sodium gluconate in a mass ratio of 5:3:

2.

8. The construction method for post-grouting sealing of construction joints in the outer wall of a gate station according to claim 1, characterized in that: Temperature gradient control in S9 using distributed fiber optic sensors is ≤2.5℃ / m.

9. The construction method for post-grouting sealing of construction joints in the outer wall of a gate station according to claim 1, characterized in that: The expanding agent in S8 is composed of ettringite and magnesium oxide in a mass ratio of 2.5:1, wherein the ettringite contains a complex of calcium sulfoaluminate and anhydrous gypsum in a mass ratio of 4:

1.

10. The construction method for post-grouting sealing of construction joints in the outer wall of a gate station according to claim 1, characterized in that: During secondary grouting in S8, a variable frequency pump is used to control the grouting flow rate at 0.6-0.8 L / min, and the drilling depth is 130-140% of the initial hole depth.

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