Prefabricating and mounting method for assembly type culvert through prostrate type adjustable combination formwork

Abstract

The invention discloses a method for prefabricating and installing a prefabricated culvert through a prostrate adjustable combination formwork, and relates to the technical field of traffic infrastructure construction. Excavation and cleaning are conducted after construction and lofting are conducted according to a drawing, foundation bearing capacity detection is conducted, and foundation pit protection is implemented; cushion layer laying and base treatment are conducted according to the foundation bearing capacity condition, and foundation formwork construction and concrete pouring are completed; mounting the prefabricated vertical wall; performing joint treatment; the adjacent vertical walls are connected through finish rolling deformed steel bars, and grouting and anchor bolt groove anchor sealing operation is completed; after reinforcing steel bar installation and formwork supporting are conducted, concrete is poured and vibrated compactly; after the component size is checked, a buffer layer is laid, the cover plate is hoisted in place, and filling and fixing are completed; the outer side of the culvert is waterproof. According to the construction method, efficient adaptation, safety, stability and quality controllability of culvert prefabrication and installation are achieved through innovations such as a prostrate type adjustable combined formwork system, industrial construction process reconstruction, a composite protection and waterproof technology and a quantitative quality control system.

Description

Technical Field

[0001] This invention relates to the field of transportation infrastructure construction technology, specifically to a method for the prefabrication and installation of culverts using a horizontally adjustable modular prefabricated formwork. Background Technology

[0002] In the field of transportation infrastructure construction, culverts, as important drainage and passage structures, directly affect the overall progress and safety of the project due to their construction quality and efficiency. Traditional culvert construction often employs cast-in-place methods or vertical fixed formwork prefabrication technology, which presents several technical bottlenecks: First, the formwork utilization rate is low. Traditional standardized formwork needs to be designed and manufactured separately for different sizes, resulting in a complex range of models, low reuse rate, serious resource waste, and high storage costs. Second, construction safety is poor. The vertical prefabricated culvert wall construction process uses the foundation slab as the bottom formwork, with wall formwork set around the perimeter. Due to the narrow foundation and high wall height, it is prone to damage in windy weather. The construction of tall formwork faces several challenges. First, it creates a large windward surface, posing a risk of formwork collapse. Second, the construction of tall formwork requires the erection of temporary scaffolding, further increasing the safety hazards of scaffolding collapse and hoisting operations. Third, it is difficult to control the construction quality. Vertical formwork construction is prone to problems such as formwork bulging and joint deformation. Inadequate sealing of pre-reserved tie rod holes in the wall can easily lead to water seepage. At the same time, rough treatment of formwork joints often causes grout leakage, affecting the quality of concrete forming. Fourth, it has poor adaptability. In complex terrains or harsh weather conditions such as desert winds and mountainous areas, the construction efficiency of traditional techniques drops significantly, making it difficult to meet the needs of projects with tight schedules and strict environmental protection requirements.

[0003] With the development of prefabricated structure technology, its advantages such as high efficiency, environmental protection, and controllable quality have gradually gained attention. However, the existing prefabricated culvert technology has not completely solved the above problems. Therefore, it is urgent to develop a new construction method that combines high efficiency, economy, and safety. Through innovation in formwork structure and modular design, the industrialization and standardization of culvert construction can be achieved to meet the needs of engineering construction in complex environments. Summary of the Invention

[0004] To solve the above-mentioned technical problems, a method for prefabrication and installation of culverts using a horizontal adjustable modular formwork is provided. This technical solution solves the aforementioned problems.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for prefabrication and installation of a culvert using a horizontally adjustable modular formwork system includes:

[0007] Precast components include steel bar processing and installation, formwork grinding, formwork assembly, application of release agent, steel bar hoisting, side formwork assembly, formwork reinforcement, concrete pouring, formwork removal and curing;

[0008] After the foundation pit is excavated and laid out according to the drawings, excavation and cleaning are carried out, the bearing capacity of the foundation is tested, and foundation pit protection is implemented.

[0009] The construction of the base layer involves laying the base layer and treating the foundation according to the bearing capacity of the ground, and then completing the foundation formwork construction and concrete pouring.

[0010] For the installation of precast walls, the position is determined by construction layout, the walls are lifted and rotated to the installation position using hoisting rings, and then fixed with temporary brackets after minor adjustments.

[0011] For joint treatment, settlement joints and segmental joints in the foundation and above the foundation are filled and waterproofed in layers with different materials;

[0012] Segmental connection, using precision-rolled threaded steel to connect adjacent vertical walls, completing grouting and anchor bolt groove sealing operations;

[0013] After pouring the base slab, installing the reinforcing bars and supporting the formwork, pour the concrete and vibrate it to compact it.

[0014] For cover plate installation, after checking the component dimensions, lay the buffer layer, hoist the cover plate into place, and complete the filling and fixing;

[0015] For waterproofing the outside of the culvert, hot asphalt coating and waterproof membrane covering and sealing are applied to the outer wall of the culvert and the joints between segments.

[0016] Preferably, the prefabrication of the components includes steel bar processing and installation, formwork grinding, formwork assembly, application of release agent, steel bar hoisting, side formwork assembly, formwork reinforcement, concrete pouring, formwork removal and curing, specifically including:

[0017] Reinforcing bar processing and installation: Reinforcing bar cutting, bending, and welding are carried out centrally at the reinforcing bar processing plant. The bars are then tied on a binding jig. After straightening, surface debris is removed, and concrete spacers are placed to ensure the protective layer thickness; the number of spacers is no less than 4 per meter. 2 Pre-embed lifting rings and connecting steel bars according to the design positioning;

[0018] For template preparation, newly arrived templates should be brushed with cement slurry and sanded 2-3 times. A horizontal, adjustable modular template should be used, based on a 0.5m x 0.5m standardized module, with dimensions adjusted using 0.5m x 0.3m adjusting blocks. The template panel is made of 5mm thick steel plate, and the base plate is supported by 0.3m high legs. The formula for calculating the template assembly dimensions is:

[0019] L = a × 0.5 + b × 0.3

[0020] In the formula, L is the total length of the template, a is the number of standardized modules, and b is the number of adjustment blocks;

[0021] Template assembly: The templates are connected by pre-reserved high-strength bolts. During assembly, the bolts are rotated from the bottom plate to the pre-reserved holes of the side formwork and fixed with a wrench to ensure that the joints are tight and without misalignment. The bottom formwork of the cover plate is made of 4mm thick stainless steel plate laid flat, and the gaps are filled with cement grout to level it.

[0022] For concrete construction, after the formwork is inspected and approved, a release agent is applied. A 50-type immersion vibrator is used to pour the concrete in layers. Before final setting, the surface is finished at least twice. The concrete is then covered with plastic film for curing for at least 7 days.

[0023] Remove the formwork when the concrete compressive strength reaches 2.5 MPa and the surface edges are undamaged. Remove the formwork in the reverse order of assembly. After removing the connecting bolts, loosen the tie rods and gently tap to release the formwork. Clean and repair before use.

[0024] Preferably, the template preparation further includes:

[0025] A slot for tie rods is pre-drilled at the top of the formwork. During construction, tie bolts are installed on the top surface to balance the lateral pressure of the concrete. The formula for calculating the lateral pressure of the concrete is:

[0026]

[0027] In the formula, F is the lateral pressure of the concrete, and γ c t0 is the initial setting time of freshly poured concrete, β1 is the correction factor for the influence of admixtures, β2 is the correction factor for the influence of concrete slump, and v is the concrete pouring speed.

[0028] Strip holes are reserved at the foundation according to the size and position of the pre-embedded steel bars. The lower part of the foundation steel bars is fixed by excavating trenches in the original ground. The side formwork is customized according to uniform specifications for the chamfer and foundation position templates, and the length direction is precisely adjusted by adjusting blocks.

[0029] Preferably, the excavation of the foundation pit, after being laid out according to the drawings, includes excavation and cleaning, conducting foundation bearing capacity testing, and implementing foundation pit protection, specifically including:

[0030] Construction layout: Measure and set out the culvert axis and excavation edge line, and extend the axis control stakes to the outside of the foundation pit for fixation; determine the plane position and elevation of the foundation pit, and retain a 10-20cm thick soil layer during mechanical excavation for manual removal and leveling;

[0031] For foundation treatment, after cleaning the foundation pit, conduct a ground bearing capacity test. If the bearing capacity does not meet the design requirements, report the treatment plan. The bottom dimensions of the foundation pit in water-permeable soil must meet the drainage and formwork design requirements. The foundation should be 0.5 to 1.0m larger than the foundation plane dimensions.

[0032] For excavation and protection, the existing sidewalls will be used for support on the side closest to the existing roadbed, while the other three sides will be excavated with a 1:1 slope, with each slope level ≤ 2.0m in height and a platform ≥ 1m wide reserved at the top; the slope stability calculation formula is:

[0033]

[0034] In the formula, K is the slope stability safety factor, and F s For anti-slip force, F t For downward force;

[0035] Loading is prohibited around the excavation pit. The pit should be enclosed with corrugated beam guardrails and protective netting, and warning signs and flashing lights should be installed.

[0036] Preferably, the construction of the base layer, including laying the base layer and treating the subgrade according to the bearing capacity of the foundation, and completing the foundation formwork construction and concrete pouring, specifically includes:

[0037] For the subbase construction, after the foundation is deemed qualified, a layer of sand and gravel subbase is laid and compacted; settlement joints are set according to the design, spaced 4-6 meters apart and flush with the settlement joints of the wall. The formula for calculating the compaction degree of the subbase is:

[0038]

[0039] In the formula, Q is the degree of compaction, and ρ d ρ is the measured dry density of the subbase. max Maximum dry density;

[0040] For template installation, the basic template is assembled from steel plates and fixed with bolts. After installation, the location of settlement joints is checked, and the top elevation of the base layer is marked with a plumb line.

[0041] When pouring concrete, use a plate vibrator to compact it until a 3-5mm layer of slurry appears on the surface. Then, use a ≥3m screed to level it. If the settlement joint shifts, hollow out the concrete on both sides and re-fix it. After molding, check the elevation and flatness. Use cement mortar to level any unqualified parts.

[0042] Preferably, the installation of the prefabricated wall involves determining the position through construction layout, using lifting rings to hoist and rotate the wall to the installation position, and then fixing it with temporary supports after minor adjustments. Specifically, this includes:

[0043] Construction layout, checking and repairing the verticality of the original culvert extension surface, marking the wall installation edge line and settlement joint position, verifying and adjusting the axis deviation, spreading a 15mm thick dry-hard mortar base and smoothing it, the formula for calculating verticality deviation is:

[0044]

[0045] In the formula, δ is the verticality deviation, h2 and h1 are the elevation differences between different points on the same vertical line, and L is the vertical distance between the two points.

[0046] For hoisting operations, first use the side lifting rings on the side wall to lift the equipment to the vicinity of the installation position, and then use the side upper lifting ring and the top lifting ring to flip it to a vertical position. Anti-tipping measures should be set up during the flipping process.

[0047] Once the wall is in place and fixed, with the bottom of the side wall less than 20cm from the base layer and no obvious swaying, place a 10mm round steel bar at the first point of contact with the ground, align it precisely, and then lower it. Use a temporary steel pipe with a top support at the bottom to adjust the verticality and joint width. Only after it is deemed satisfactory can the hoisting wire rope be loosened. After the wall is in place, cut off five lifting points to ensure a tight joint and a flat surface.

[0048] Preferably, the joint treatment, specifically the layered filling and waterproofing of settlement joints and segmental joints in the foundation and above the foundation using different materials, includes:

[0049] For the treatment of the foundation joints, the middle of the foundation slab should be filled with asphalt-impregnated hemp or water-swellable rubber, with a width twice the width of the settlement joint, and the inside of the channel should be filled with 5cm thick sealant.

[0050] For wall joint treatment, fill the chamfered corners of the sides and top surfaces above the foundation with 5cm thick sealant; apply 120cm wide hot asphalt to the outside and attach 100cm wide SBS modified bitumen waterproof membrane.

[0051] In terms of process control, after the installation of a single precast wall section is completed, water-swellable rubber strips are filled between the settlement joint and the segment joint before the installation of the next wall section can proceed.

[0052] Preferably, the segmental connection uses precision-rolled threaded steel bars to connect adjacent vertical walls, and the grouting and anchor bolt groove sealing operation specifically includes:

[0053] After the prefabricated walls are installed and deemed qualified, φ32 precision-rolled threaded steel bars are used to connect adjacent prefabricated walls. The nuts are tightened to ensure a secure connection. The formula for calculating the bolt preload is:

[0054] E=K×d×σ p

[0055] In the formula, E is the preload, K is the tightening coefficient, d is the nominal diameter of the bolt, and σ p The bolt yield strength;

[0056] Before grouting, the mixer should be wetted by adding water and running empty. The finished grouting material should be mixed for no less than 2 minutes. Unloading should be completed in one go. It is forbidden to add water directly to adjust the grout with reduced fluidity. The grout should be filtered through a fine screen and then enter the grouting machine to remove residual water, debris and air from the pump.

[0057] Grouting operations should be completed evenly, slowly, and continuously in one go, without interruption. After grouting, dry-hardened mortar should be used to fill the working windows in multiple applications. Small stone concrete should not be used for filling.

[0058] No bolts are used at the settlement joints, but the anchor sealing work must be completed according to the same standards.

[0059] Preferably, the pouring of the base slab, after the installation of reinforcing bars and formwork support, involves pouring concrete and vibrating it to ensure compaction.

[0060] For steel reinforcement construction, the steel bars are centrally processed in the processing plant and then transported to the site for binding, and the operation is carried out in accordance with the design specifications to reduce waste;

[0061] For formwork support, the bottom slab formwork is assembled from steel formwork, the joints are sealed with double-sided adhesive, the outer side is reinforced with transverse steel pipes, the top is locked with tie rods, and the inner side is marked with the control elevation of the concrete top surface.

[0062] C30 concrete was used for concrete pouring, with a slump controlled between 120 and 160 mm. The concrete was loaded into the formwork by a truck crane and poured in parallel layers. A 50-type immersion vibrator was used to compact the concrete.

[0063] Preferably, the waterproofing of the culvert exterior, specifically the application of hot asphalt coating and waterproof membrane sealing to the culvert exterior wall and segment joints, includes:

[0064] Base treatment: clean the base surface where the culvert meets the backfill and the joints between sections, remove cement mortar residue, dust and debris, and ensure that the base is dry with a moisture content of ≤9%;

[0065] For waterproofing construction, apply three coats of hot asphalt evenly to the contact surface between the culvert and the backfill, apply primer to the joints of the segments, allow it to dry for more than 8 hours, and then lay a 100mm wide SBS waterproof membrane.

[0066] For sealing, after the roll material is laid, apply sealant to the overlapping parts, ends and joints to ensure a tight seal and no leakage.

[0067] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0068] 1. The project adopts a horizontal adjustable modular formwork based on 0.5m×0.5m standardized modules. The size can be flexibly adjusted by 0.5m×0.3m adjustment blocks. This abandons the traditional extensive mode of "one size, one formwork". The number of formwork models is reduced by more than 60%, the reuse rate is significantly improved, and the storage management cost is reduced by more than 35%. This realizes the industrialized construction concept of "building more with less and adjusting larger with smaller", which greatly saves material and management costs.

[0069] 2. The horizontal formwork design reduces the overall height of the formwork and significantly lightens the weight of individual formwork panels, reducing the load on hoisting machinery and the risks associated with hoisting operations. Compared to vertical formwork, there is no need to erect temporary scaffolding, which effectively reduces the safety hazards of formwork overturning and scaffolding collapse in windy areas. It also avoids potential injuries to operators from tall formwork, comprehensively improving the safety of the construction process. The top of the formwork has pre-reserved grooves for tie rods and uses pre-reserved high-strength bolts for splicing, effectively balancing the lateral pressure of the concrete and completely solving problems such as joint leakage and formwork bulging in traditional processes. The horizontal prefabrication process facilitates the installation of the steel reinforcement cage and concrete vibration, avoiding the problem of insufficient compaction caused by the height of vertical formwork, reducing defects such as honeycomb, pitting, and voids in the concrete, and increasing the concrete appearance qualification rate to over 99%. The joint treatment adopts a layered filling and waterproofing process, effectively solving the leakage problem.

[0070] 3. The modular assembly process uses high-strength bolts for rapid connection, significantly improving the efficiency of formwork disassembly while reducing bolt wear. Based on the industrialized construction process of "prefabrication assembly + overall hoisting," it realizes the assembly line operation of component prefabrication and on-site installation, improving construction efficiency by more than 40% and greatly shortening the construction cycle. It is especially suitable for projects with tight schedules. This method provides an efficient solution for culvert construction in harsh environments such as desert winds and mountainous areas through lightweight formwork design and optimized wind resistance stability. The modular design and high reusability reduce material waste and carbon emissions, meeting environmental protection construction requirements and having significant economic and social benefits. Attached Figure Description

[0071] Figure 1 This is a flowchart illustrating the overall steps of the present invention.

[0072] Figure 2 This is a flowchart of steps S1 in this invention;

[0073] Figure 3 This is a flowchart of step S2 in the present invention. Detailed Implementation

[0074] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0075] Reference Figure 1 As shown, a method for prefabrication and installation of a culvert using a horizontally adjustable modular formwork system includes:

[0076] S1: Precast components, including steel bar processing and installation, formwork grinding, formwork assembly, application of release agent, steel bar hoisting, side formwork assembly, formwork reinforcement, concrete pouring, formwork removal and curing;

[0077] S2: Excavation of the foundation pit. After the construction layout is carried out according to the drawings, excavation and cleaning are carried out, the bearing capacity of the foundation is tested and foundation pit protection is implemented.

[0078] S3: Base layer construction, laying the base layer and treating the foundation according to the bearing capacity of the foundation, and completing the foundation formwork construction and concrete pouring;

[0079] S4: Precast wall installation: The position is determined by construction layout, the wall is lifted and rotated to the installation position using lifting rings, and then fixed with temporary brackets after minor adjustments;

[0080] S5: Joint treatment, the settlement joints and segmental joints of the foundation and the parts above the foundation shall be filled and waterproofed with different materials in layers;

[0081] S6: Segmental connection, using precision-rolled threaded steel to connect adjacent vertical walls, completing grouting and anchor bolt groove sealing operations;

[0082] S7: After the base slab is poured, the concrete is poured and vibrated to compact it after the reinforcement and formwork support are installed.

[0083] S8: Cover plate installation: After checking the component dimensions, lay the buffer layer, hoist the cover plate into place, and complete the filling and fixing;

[0084] S9: Waterproofing of the outside of the culvert, hot asphalt coating and waterproof membrane covering and sealing are applied to the outer wall of the culvert and the joints of the segments.

[0085] Reference Figure 2 As shown, S1 specifically includes:

[0086] S101: Reinforcing bar processing and installation. Reinforcing bar cutting, bending, and welding are carried out centrally at the reinforcing bar processing plant. The bars are then tied on a binding jig. After straightening, surface debris is removed from the reinforcing bars. Concrete spacers are installed to ensure the thickness of the protective layer, with a minimum of 4 spacers per meter. 2 Pre-embed lifting rings and connecting steel bars according to the design positioning;

[0087] S102: Template preparation. Newly arrived templates should be brushed with cement slurry and sanded 2-3 times. A horizontal, adjustable modular template should be used, based on a 0.5m × 0.5m standardized module. Dimensions should be adjusted using 0.5m × 0.3m adjusting blocks. The template panel is made of 5mm thick steel plate, and the base plate is supported by 0.3m high legs. The template assembly dimensions are calculated using the following formula:

[0088] L = a × 0.5 + b × 0.3

[0089] In the formula, L is the total length of the template, a is the number of standardized modules, and b is the number of adjustment blocks;

[0090] S103: Template assembly. The template is connected by pre-reserved high-strength bolts. When assembling, the bolts are rotated from the bottom plate to the pre-reserved holes of the side formwork and fixed with a wrench to ensure that the joints are tight and without misalignment. The bottom formwork of the cover plate is made of 4mm thick stainless steel plate laid flat, and the gaps are filled with cement grout to level it.

[0091] S104: Concrete construction, after the formwork is accepted, apply release agent, use a 50-type immersion vibrator to pour in layers, perform no less than 2 finishing operations before final setting, cover with plastic film for curing, and the curing time shall be no less than 7 days.

[0092] S105: Formwork removal. When the concrete compressive strength reaches 2.5 MPa and the surface edges are undamaged, remove the formwork in the reverse order of assembly. After removing the connecting bolts, loosen the tie rods and gently tap to release the formwork. Clean and repair for later use.

[0093] The system features an innovative horizontal adjustable modular template system that combines standardized modules and adjustment blocks to achieve multi-size adaptation, replacing the traditional "one size, one template" model. The template splicing adopts a base plate rotating bolt design, which solves the problems of low disassembly and assembly efficiency and high bolt wear of traditional templates.

[0094] S102 further includes:

[0095] A slot for tie rods is pre-drilled at the top of the formwork. During construction, tie bolts are installed on the top surface to balance the lateral pressure of the concrete. The formula for calculating the lateral pressure of the concrete is:

[0096]

[0097] In the formula, F is the lateral pressure of the concrete, and γ c t0 is the initial setting time of freshly poured concrete, β1 is the correction factor for the influence of admixtures, β2 is the correction factor for the influence of concrete slump, and v is the concrete pouring speed.

[0098] Strip holes are reserved at the foundation according to the size and position of the pre-embedded steel bars. The lower part of the foundation steel bars is fixed by excavating trenches in the original ground. The side formwork is customized according to uniform specifications for the chamfer and foundation position templates, and the length direction is precisely adjusted by adjusting blocks.

[0099] The top tie rod slot design replaces the traditional pre-reserved tie rod holes in the wall, solving the water seepage problem caused by poor sealing of tie rod holes at the root; the tie bolt configuration is optimized by accurately calculating the concrete lateral pressure to avoid the risk of formwork deformation and bulging.

[0100] Reference Figure 3 As shown, S2 specifically includes:

[0101] S201: Construction layout, setting out the culvert axis and excavation edge line, extending the axis control stakes to the outside of the foundation pit for fixation; determining the plane position and elevation of the foundation pit, and retaining a 10-20cm thick soil layer for manual removal and leveling during mechanical excavation;

[0102] S202: Foundation treatment. After the foundation pit is cleaned, a foundation bearing capacity test is conducted. If the design requirements are not met, a treatment plan shall be reported. The bottom dimensions of the foundation pit in water-permeable soil must meet the drainage and formwork design requirements. The foundation dimensions shall be 0.5 to 1.0m larger than the foundation plane dimensions.

[0103] S203: Excavation protection; the side closest to the existing roadbed utilizes the existing sidewalls for support; the other three sides are excavated with a 1:1 slope, with each slope level ≤ 2.0m in height, and a platform ≥ 1m wide reserved at the top; the slope stability calculation formula is:

[0104]

[0105] In the formula, K is the slope stability safety factor, and F s For anti-slip force, F t For downward force;

[0106] Loading is prohibited around the foundation pit. The pit should be surrounded by corrugated beam guardrails and protective netting, and warning signs and flashing lights should be installed.

[0107] The innovative composite protection system of "existing structural support + graded slope" is adopted, combined with quantitative calculation of slope stability, to solve the problem of large disturbance to the existing roadbed caused by traditional foundation pit excavation, and is especially suitable for culvert construction in reconstruction and expansion projects.

[0108] S3 specifically includes:

[0109] S301: Subbase construction. After the foundation is qualified, a layer of gravel subbase is laid and compacted. Settlement joints are set according to the design, with a spacing of 4-6 meters and flush with the settlement joints of the wall. The formula for calculating the compaction degree of the subbase is:

[0110]

[0111] In the formula, Q is the degree of compaction, and ρ d ρ is the measured dry density of the subbase. max Maximum dry density;

[0112] S302: Template installation. The basic template is assembled from steel plates and fixed with bolts. After installation, the location of settlement joints is checked, and the top elevation of the base layer is marked with a plumb line.

[0113] S303: Concrete pouring, use a plate vibrator to compact it until a 3-5mm laitance appears on the surface, and use a ≥3m scraper to level it. If the settlement joint is displaced, hollow out the concrete on both sides and re-fix it. After molding, check the elevation and flatness. Use cement mortar to level any unqualified parts.

[0114] By using a "straight and smooth" settlement joint control process, the settlement joints of the foundation and the wall are precisely aligned, solving the leakage problem caused by misalignment of settlement joints in traditional construction; quantitative control of the compaction of the subbase ensures the uniform transfer of the foundation bearing capacity.

[0115] S4 specifically includes:

[0116] S401: Construction layout, checking and repairing the verticality of the original culvert extension surface, marking the wall installation edge line and settlement joint position, verifying and adjusting the axis deviation, spreading a 15mm thick dry-hard mortar base and smoothing it, the formula for calculating the verticality deviation is:

[0117]

[0118] In the formula, δ is the verticality deviation, h2 and h1 are the elevation differences between different points on the same vertical line, and L is the vertical distance between the two points.

[0119] S402: For hoisting operations, first use the side lifting ring on the side wall to hoist the equipment to the vicinity of the installation position, and then use the side upper lifting ring and the top lifting ring to flip it to a vertical position. When flipping, take measures to prevent tipping.

[0120] S403: When the wall is in place and fixed, and the bottom of the side wall is less than 20cm from the base layer and there is no obvious swaying, place a 10mm round steel bar at the first landing point, and lower it after precise alignment; use a temporary steel pipe with a top support at the bottom to support and adjust the verticality and joint width. Only after it is qualified can the hoisting wire rope be loosened; after the wall is in place, cut off five lifting points to ensure that the splicing is tight and flat with the top surface.

[0121] We developed an installation process of "multi-point coordinated flipping + top support fine adjustment" to solve the problem of difficult posture control during the hoisting of precast walls; and reduced the deviation of the bottom mortar extrusion by using 10mm round steel auxiliary positioning technology to achieve a verticality deviation of ≤3mm / m for wall installation.

[0122] S5 specifically includes:

[0123] S501: Treatment of foundation joints: The middle of the foundation slab is filled with asphalt-impregnated hemp or water-swellable rubber, with a width twice the width of the settlement joint, and the inside of the channel is filled with 5cm thick sealant.

[0124] S502: Wall joint treatment: fill the chamfered corners of the sides and top surfaces above the foundation with 5cm thick sealant; apply 120cm wide hot asphalt to the outside and attach 100cm wide SBS modified bitumen waterproof membrane.

[0125] S503: Process control: After the installation of a single precast wall section is completed, water-swellable rubber strips should be filled between the settlement joint and the segment joint before the installation of the next wall section can proceed.

[0126] The composite joint treatment process of "layered filling + internal and external waterproofing" is adopted. Different sealing materials are used for the foundation and the wall to solve the problem of rapid failure of traditional single waterproofing measures for culvert joints. Process control nodes are introduced to ensure the continuity of joint treatment.

[0127] S6 specifically includes:

[0128] S601: Connection Preparation. After the precast walls are installed successfully, use φ32 precision-rolled threaded steel bars to connect adjacent precast walls, and tighten the nuts to ensure a secure connection. The formula for calculating the bolt preload is:

[0129] E=K×d×σ p

[0130] In the formula, E is the preload, K is the tightening coefficient, d is the nominal diameter of the bolt, and σ p The bolt yield strength;

[0131] S602: Grouting construction. Before grouting, the mixer is wetted by adding water and running empty. The finished grouting material is mixed for no less than 2 minutes. Unloading must be completed in one go. It is forbidden to directly add water to adjust the grout with reduced fluidity. The grout enters the grouting machine after being filtered through a fine screen. Residual water, debris and air in the pump are discharged.

[0132] S603: Grouting operation: Grouting should be completed in one go, evenly, slowly and continuously, without interruption. After grouting, dry hard mortar should be used to fill the working window in multiple times. Small stone concrete is prohibited for filling.

[0133] S604: No bolted connections are required at settlement joints, but the sealing and anchoring work must be completed according to the same standard;

[0134] An innovative segmental connection process combining precision-rolled threaded steel connection and pressure grouting is used to solve the problem of insufficient connection rigidity of precast components by quantitative control of bolt pre-tightening force and continuous grouting. Dry-hardened mortar is used to replace traditional small-aggregate concrete for sealing and anchoring, avoiding filling defects of insufficient density.

[0135] Specifically, S7 includes:

[0136] S701: Reinforcing steel construction. After the reinforcing steel is centrally processed in the processing plant, it is transported to the site for binding. The operation is carried out in accordance with the design specifications to reduce waste.

[0137] S702: Formwork support, the bottom slab formwork is assembled with steel formwork, the joints are sealed with double-sided tape, the outer side is reinforced with horizontal steel pipes, the top is locked with tie rods, and the inner side is marked with the control elevation of the concrete top surface.

[0138] S703: Concrete pouring, using C30 concrete, with a slump controlled at 120-160mm, is delivered into the formwork by truck crane, poured in parallel layers, and compacted using a 50-type immersion vibrator.

[0139] The base slab formwork adopts a triple reinforcement system of "double-sided adhesive sealing + horizontal steel pipe back ribs + tie rod locking" to solve the problems of grout leakage and formwork bulging in traditional base slab pouring; the concrete slump is precisely controlled to ensure the compactness of the pouring, which is especially suitable for the vibration requirements of prone construction.

[0140] S9 specifically includes:

[0141] S901: Base treatment, clean the base surface where the culvert meets the backfill and the joints of the segments, remove cement mortar residue, dust and debris, and ensure that the base is dry with a moisture content of ≤9%;

[0142] S902: Waterproof layer construction: Apply three coats of hot asphalt evenly to the contact surface between the culvert and the backfill, apply primer at the joint of the segments, let it dry for more than 8 hours, and then lay a 100mm wide SBS waterproof membrane.

[0143] S903: Sealing treatment. After the roll material is laid, apply sealant to the overlapping parts, ends and joints to ensure a tight seal and no leakage.

[0144] A three-dimensional waterproofing system consisting of "base layer dryness control + multiple layers of protection + joint reinforcement" is established. By quantitatively controlling the moisture content of the base layer and using the roll material overlap sealing process, the problem of insufficient waterproofing durability on the outside of the culvert is solved, which is especially suitable for waterproofing needs in complex geological environments.

[0145] In summary, the advantages of this invention are:

[0146] It is the first to use a combined template structure based on 0.5m×0.5m standardized modules and supplemented by 0.5m×0.3m adjusting blocks. It can adapt to culverts of various specifications through the template combination size calculation formula, replacing the traditional extensive mode of "one size, one template". The template reuse rate is increased by more than 60%. The bottom plate rotating bolt splicing design solves the pain points of low disassembly and assembly efficiency and high bolt wear of traditional templates. At the same time, the top tie rod groove replaces the wall pre-reserved tie rod hole, eliminating the risk of water seepage from the root.

[0147] A fully integrated construction system encompassing prefabrication, installation, and protection is established, precisely connecting component prefabrication and on-site installation through standardized procedures. An innovative prone prefabrication process is adopted to reduce formwork height and minimize the risk of tall formwork tipping over. Through "multi-point coordinated rotation + top support fine-tuning" installation technology, the verticality deviation of prefabricated walls is achieved to ≤3mm / m, solving the problem of hoisting posture control and improving overall construction efficiency by 40%.

[0148] A composite foundation pit protection system of "existing structure support + graded slope" was developed, which combines slope stability quantitative calculation formula to ensure excavation safety. It is especially suitable for the protection of existing roadbeds in reconstruction and expansion projects. The method of concrete lateral pressure calculation and tie bolt configuration is innovated. The formwork deformation is avoided through scientific quantitative control. The "straight and smooth" technology of settlement joint between foundation and wall solves the leakage problem caused by misalignment of settlement joint in traditional construction.

[0149] A composite joint treatment process of "layered filling + internal and external waterproofing" was established. The base uses a combination of asphalt hemp and water-swellable rubber, and the wall uses a triple protection of sealant + hot asphalt + SBS membrane to form a differentiated waterproofing system. A quantitative control standard of ≤9% moisture content of the base layer was introduced. Combined with the membrane overlap sealing reinforcement process, a three-dimensional waterproof network was constructed to greatly improve the durability of the culvert.

[0150] We developed a segmental fixing technology that combines precision-rolled threaded steel connections with pressure grouting, achieving precise control of connection stiffness through bolt preload calculation formulas. We adopted a continuous grouting process using precast grout material, coupled with dry-hardened mortar anchoring to replace traditional small-aggregate concrete, avoiding defects such as incomplete filling. Our innovative base slab formwork utilizes a triple reinforcement system of "double-sided adhesive sealing + transverse steel pipe back ribs + tie rod locking" to solve problems of grout leakage and formwork bulging during pouring.

[0151] Establish a quantitative control system covering key indicators such as compaction degree of subbase, lateral pressure of concrete, and verticality deviation. Through technical means such as compaction degree calculation formula, slump range control (120-160mm), and verticality deviation calculation formula, achieve full-process quality control from foundation treatment to component installation, increase the concrete appearance qualification rate to over 99%, and reduce the overall project quality fluctuation range by 50%.

[0152] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A method for prefabrication and installation of a culvert using a horizontally adjustable modular prefabricated formwork, characterized in that, include: S1: Precast components, including steel bar processing and installation, formwork grinding, formwork assembly, application of release agent, steel bar hoisting, side formwork assembly, formwork reinforcement, concrete pouring, formwork removal and curing; S2: Excavation of the foundation pit. After the construction layout is carried out according to the drawings, excavation and cleaning are carried out, the bearing capacity of the foundation is tested and foundation pit protection is implemented. S3: Base layer construction, laying the base layer and treating the foundation according to the bearing capacity of the foundation, and completing the foundation formwork construction and concrete pouring; S4: Precast wall installation: The position is determined by construction layout, the wall is lifted and rotated to the installation position using lifting rings, and then fixed with temporary brackets after minor adjustments; S5: Joint treatment, the settlement joints and segmental joints of the foundation and the parts above the foundation shall be filled and waterproofed with different materials in layers; S6: Segmental connection, using precision-rolled threaded steel to connect adjacent vertical walls, completing grouting and anchor bolt groove sealing operations; S7: After the base slab is poured, the concrete is poured and vibrated to compact it after the reinforcement and formwork support are installed. S8: Cover plate installation: After checking the component dimensions, lay the buffer layer, hoist the cover plate into place, and complete the filling and fixing; S9: Waterproofing of the outside of the culvert, hot asphalt coating and waterproof membrane covering and sealing are applied to the outer wall of the culvert and the joints of the segments.

2. The method for prefabrication and installation of a horizontally adjustable modular prefabricated culvert according to claim 1, characterized in that, S1 specifically includes: S101: Reinforcing bar processing and installation. Reinforcing bar cutting, bending, and welding are carried out centrally at the reinforcing bar processing plant. The bars are then tied on a binding jig. After straightening, surface debris is removed from the reinforcing bars. Concrete spacers are installed to ensure the thickness of the protective layer, with a minimum of 4 spacers per meter. 2 Pre-embed lifting rings and connecting steel bars according to the design positioning; S102: Template preparation. Newly arrived templates should be brushed with cement slurry and sanded 2-3 times. A horizontal, adjustable modular template should be used, based on a 0.5m × 0.5m standardized module. Dimensions should be adjusted using 0.5m × 0.3m adjusting blocks. The template panel is made of 5mm thick steel plate, and the base plate is supported by 0.3m high legs. The template assembly dimensions are calculated using the following formula: L = a × 0.5 + b × 0.3 In the formula, L is the total length of the template, a is the number of standardized modules, and b is the number of adjustment blocks; S103: Template assembly. The template is connected by pre-reserved high-strength bolts. When assembling, the bolts are rotated from the bottom plate to the pre-reserved holes of the side formwork and fixed with a wrench to ensure that the joints are tight and without misalignment. The bottom formwork of the cover plate is made of 4mm thick stainless steel plate laid flat, and the gaps are filled with cement grout to level it. S104: Concrete construction, after the formwork is accepted, apply release agent, use a 50-type immersion vibrator to pour in layers, perform no less than 2 finishing operations before final setting, cover with plastic film for curing, and the curing time shall be no less than 7 days. S105: Formwork removal. When the concrete compressive strength reaches 2.5 MPa and the surface edges are undamaged, remove the formwork in the reverse order of assembly. After removing the connecting bolts, loosen the tie rods and gently tap to release the formwork. Clean and repair for later use.

3. The method for prefabrication and installation of a horizontally adjustable modular prefabricated culvert according to claim 2, characterized in that, S102 further includes: A slot for tie rods is pre-drilled at the top of the formwork. During construction, tie bolts are installed on the top surface to balance the lateral pressure of the concrete. The formula for calculating the lateral pressure of the concrete is: In the formula, F is the lateral pressure of the concrete, and γ c t0 is the initial setting time of freshly poured concrete, β1 is the correction factor for the influence of admixtures, β2 is the correction factor for the influence of concrete slump, and v is the concrete pouring speed. Strip holes are reserved at the foundation according to the size and position of the pre-embedded steel bars. The lower part of the foundation steel bars is fixed by excavating trenches in the original ground. The side formwork is customized according to uniform specifications for the chamfer and foundation position templates, and the length direction is precisely adjusted by adjusting blocks.

4. The method for prefabrication and installation of a culvert using a horizontally adjustable modular prefabricated formwork as described in claim 3, characterized in that, S2 specifically includes: S201: Construction layout, setting out the culvert axis and excavation edge line, extending the axis control stakes to the outside of the foundation pit for fixation; determining the plane position and elevation of the foundation pit, and retaining a 10-20cm thick soil layer for manual removal and leveling during mechanical excavation; S202: Foundation treatment. After the foundation pit is cleaned, a foundation bearing capacity test is conducted. If the design requirements are not met, a treatment plan shall be reported. The bottom dimensions of the foundation pit in water-permeable soil must meet the drainage and formwork design requirements. The foundation dimensions shall be 0.5 to 1.0m larger than the foundation plane dimensions. S203: Excavation protection; the side closest to the existing roadbed utilizes the existing sidewalls for support; the other three sides are excavated with a 1:1 slope, with each slope level ≤ 2.0m in height, and a platform ≥ 1m wide reserved at the top; the slope stability calculation formula is: In the formula, K is the slope stability safety factor, and F s For anti-slip force, F t For downward force; Loading is prohibited around the excavation pit. The pit should be enclosed with corrugated beam guardrails and protective netting, and warning signs and flashing lights should be installed.

5. The method for prefabrication and installation of a horizontally adjustable modular prefabricated culvert according to claim 1, characterized in that, S3 specifically includes: S301: Subbase construction. After the foundation is qualified, a layer of gravel subbase is laid and compacted. Settlement joints are set according to the design, with a spacing of 4-6 meters and flush with the settlement joints of the wall. The formula for calculating the compaction degree of the subbase is: In the formula, Q is the degree of compaction, and ρ d ρ is the measured dry density of the subbase. max Maximum dry density; S302: Template installation. The basic template is assembled from steel plates and fixed with bolts. After installation, the location of settlement joints is checked, and the top elevation of the base layer is marked with a plumb line. S303: Concrete pouring, use a plate vibrator to compact it until a 3-5mm layer of laitance appears on the surface, and level it with a ≥3m screed. If the settlement joint shifts, hollow out the concrete on both sides and re-fix it. After molding, check the elevation and flatness. Use cement mortar to level any unqualified parts.

6. The method for prefabrication and installation of a horizontally adjustable modular prefabricated culvert according to claim 1, characterized in that, S4 specifically includes: S401: Construction layout, checking and repairing the verticality of the original culvert extension surface, marking the wall installation edge line and settlement joint position, verifying and adjusting the axis deviation, spreading a 15mm thick dry-hard mortar base and smoothing it, the formula for calculating the verticality deviation is: In the formula, δ is the verticality deviation, h2 and h1 are the elevation differences between different points on the same vertical line, and L is the vertical distance between the two points. S402: For hoisting operations, first use the side lifting ring on the side wall to hoist the equipment to the vicinity of the installation position, and then use the side upper lifting ring and the top lifting ring to flip it to a vertical position. When flipping, take measures to prevent tipping. S403: When the wall is in place and fixed, and the bottom of the side wall is less than 20cm from the base layer and there is no obvious swaying, place a 10mm round steel bar at the first landing point, and lower it after precise alignment; use a temporary steel pipe with a top support at the bottom to support and adjust the verticality and joint width. Only after it is qualified can the hoisting wire rope be loosened; after the wall is in place, cut off five lifting points to ensure that the splicing is tight and flat with the top surface.

7. The method for prefabrication and installation of a horizontally adjustable modular prefabricated culvert according to claim 1, characterized in that, S5 specifically includes: S501: Treatment of foundation joints: The middle of the foundation slab is filled with asphalt-impregnated hemp or water-swellable rubber, with a width twice the width of the settlement joint, and the inside of the channel is filled with 5cm thick sealant. S502: Wall joint treatment: fill the chamfered corners of the sides and top surfaces above the foundation with 5cm thick sealant; apply 120cm wide hot asphalt to the outside and attach 100cm wide SBS modified bitumen waterproof membrane. S503: Process control. After the installation of a single precast wall section is completed, water-swellable rubber strips must be filled between the settlement joint and the segment joint before the installation of the next wall section can proceed.

8. The method for prefabrication and installation of a culvert using a horizontally adjustable modular prefabricated formwork as described in claim 1, characterized in that, S6 specifically includes: S601: Connection Preparation. After the precast walls are installed successfully, use φ32 precision-rolled threaded steel bars to connect adjacent precast walls, and tighten the nuts to ensure a secure connection. The formula for calculating the bolt preload is: E=K×d×σ p In the formula, E is the preload, K is the tightening coefficient, d is the nominal diameter of the bolt, and σ p The bolt yield strength; S602: Grouting construction. Before grouting, the mixer is wetted by adding water and running empty. The finished grouting material is mixed for no less than 2 minutes. Unloading must be completed in one go. It is forbidden to directly add water to adjust the grout with reduced fluidity. The grout enters the grouting machine after being filtered through a fine screen. Residual water, debris and air in the pump are discharged. S603: Grouting operation: Grouting should be completed in one go, evenly, slowly and continuously, without interruption. After grouting, dry hard mortar should be used to fill the working window in multiple times. Small stone concrete is prohibited for filling. S604: No bolted connections are required at settlement joints, but the sealing and anchoring work must be completed according to the same standard.

9. The method for prefabrication and installation of a culvert using a horizontally adjustable modular prefabrication system according to claim 1, characterized in that, Specifically, S7 includes: S701: Reinforcing steel construction. After the reinforcing steel is centrally processed in the processing plant, it is transported to the site for binding. The operation is carried out in accordance with the design specifications to reduce waste. S702: Formwork support, the bottom slab formwork is assembled with steel formwork, the joints are sealed with double-sided tape, the outer side is reinforced with horizontal steel pipes, the top is locked with tie rods, and the inner side is marked with the concrete top surface control elevation. S703: Concrete pouring, using C30 concrete, with a slump controlled between 120 and 160 mm, is delivered into the formwork by truck crane, poured in parallel layers, and compacted using a 50-type immersion vibrator.

10. The method for prefabrication and installation of a culvert using a horizontally adjustable modular prefabricated formwork according to claim 1, characterized in that, S9 specifically includes: S901: Base treatment, clean the base layer at the contact surface between the culvert and the backfill and at the joints of the segments, remove cement mortar residue, dust and debris, and ensure that the base layer is dry with a moisture content of ≤9%; S902: Waterproof layer construction: Apply three coats of hot asphalt evenly to the contact surface between the culvert and the backfill, apply primer at the joint of the segments, dry for more than 8 hours, and then lay a 100mm wide SBS waterproof membrane. S903: Sealing treatment. After the roll material is laid, sealant is applied to the overlapping parts, ends and joints to ensure a tight seal and no leakage.

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