Reverse-construction-method sheet-pile wall construction structure capable of achieving multi-time layered pouring and quality control method of reverse-construction-method sheet-pile wall construction structure

Abstract

The invention provides a top-down-method sheet-pile wall construction structure capable of achieving multi-time and layered pouring and a quality control method of the top-down-method sheet-pile wall construction structure. Relates to the technical field of building construction, and comprises a formwork support system, the formwork support system comprises a customized steel formwork and an adjustable supporting vertical rod, and the customized steel formwork is provided with a reserved hole for a reinforcing steel bar to penetrate through. According to the top-down-method-based sheet-pile wall construction structure and the quality control method, a stable formwork support system composed of the customized steel formworks, the adjustable supporting vertical rods and the horizontal connecting rods is constructed, so that a top-down-method-based sheet-pile wall has higher overall rigidity and lateral deformation resistance in the formwork erecting stage. Regular reserved holes formed in the formwork are matched with the laser measurement and calibration technology, so that the steel bar perforating position is kept consistent with the design size, the thickness of a steel bar protection layer is stabilized within a controllable range, and the structure weakening risk caused by steel bar deviation is reduced.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, specifically to a reverse construction method for pile-slab wall with multi-stage and layered casting and a method for quality control. Background Technology

[0002] Currently, the reverse-construction pile-slab wall construction technology is widely used in deep foundation pit support and slope reinforcement projects, especially in the complex geological conditions of loess areas. This method enhances the stability of the foundation pit and slope through the combination of pile-slab wall structures. Traditional construction techniques employ integral or segmented casting, relying on a formwork support system for structural support and concrete pouring. This system typically consists of steel formwork, adjustable support pillars such as adjustable top supports, and connecting rods, effectively supporting the loads during construction and ensuring smooth concrete pouring. Existing construction methods, through modular design, ensure accurate reinforcement positioning and high concrete pouring precision, thereby improving construction quality.

[0003] However, existing technologies have significant drawbacks during construction. Traditional support systems lack overall rigidity and stability, making them prone to uneven settlement under concrete pouring loads and their own weight. This leads to uncontrolled slope of the bottom formwork and difficulty in ensuring arching accuracy. The adjustable top support is not a rigid whole with the uprights and formwork, making it highly susceptible to rotational loosening under the periodic vibration loads of pumping and compaction. This causes the support point elevation to sink, exacerbating the risk of settlement and deformation of the bottom formwork. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a construction structure and quality control method for pile-slab walls constructed using a phased and layered pouring method. The technical problem this invention aims to solve is: how to improve the adjustment accuracy by constructing a stable formwork support system and adopting a phased and layered concrete pouring method with controlled parameters to address the issues of support deformation and rebar misalignment during the construction of pile-slab walls using a reverse construction method.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: a construction structure and quality control method for a pile-slab wall using a phased and layered pouring method, comprising: a formwork support system, wherein the formwork support system includes a customized steel formwork and adjustable support poles, wherein the customized steel formwork has reserved holes for passing through reinforcing bars, and the top end of the adjustable support poles is detachably connected to the customized steel formwork through a rigid connector.

[0006] A connection stabilization system is provided, which includes a horizontal connecting rod that connects the adjustable support uprights into an integral support system via a disc buckle connector.

[0007] Preferably, the diameter of the reserved hole is 20mm and the center-to-center distance is 185mm×150mm. The adjustable support pole adopts a threaded rotation adjustment mechanism. The rigid connector includes a wedge-shaped locking block and a double clamp with a pin hole. The adjustment range of the threaded rotation adjustment mechanism is 450-700mm.

[0008] A quality control method for a pile-slab wall construction structure constructed using the reverse construction method with phased and layered casting includes:

[0009] S1. Conduct a joint review and technical briefing on the construction drawings to form a template support system. The joint review and technical briefing includes detailed design of the plan drawings and three-dimensional modeling design.

[0010] S2. The template support system is installed and debugged to form a support installation system. The installation and debugging process includes mechanical hoisting and manual assembly.

[0011] S3. The reinforcing bars are positioned based on the reserved holes of the bracket installation system, and a reinforcing bar binding system is formed through the positioning process. The positioning process adopts a laser scanning system and a digital reinforcing bar binding device.

[0012] S4. Based on the bracket installation system and the rebar tying system, the concrete is poured in stages and layers to form a slab wall concrete structure. The staged pouring process adopts a concrete pouring method.

[0013] S5. After the concrete structure of the wall panel reaches the design strength, the formwork support system is dismantled, and a construction joint structure is formed based on the dismantling process. The construction joint structure is then subjected to quality inspection.

[0014] Preferably, the detailed design of the 2D drawings is done using CAD, and the 3D modeling design is done using BIM technology.

[0015] Preferably, the mechanical hoisting adopts automated hoisting equipment, which hoists and positions the template support system to form a preliminary hoisting and positioning structure. The manual assembly then fine-tunes and fixes the preliminary hoisting and positioning structure to form the support installation system.

[0016] Preferably, the laser scanning system performs measurement processing on the reserved hole, the measurement processing including three-dimensional point cloud data acquisition and design drawing comparison, to ensure that the rebar is placed in the preset position, and the digital rebar binding equipment dynamically adjusts the placement position of the rebar after the measurement processing, thereby forming the rebar binding system through the dynamic adjustment of the placement position.

[0017] Preferably, the concrete pouring method includes pumped concrete pouring and immersion vibrator compaction treatment. The pumped concrete pouring uniformly delivers and distributes the concrete, while the immersion vibrator compaction treatment compacts the concrete. The synergistic effect of uniform delivery and compaction forms the concrete structure of the slab wall.

[0018] Preferably, the single pouring height of the concrete pouring method does not exceed 2 meters, and the layer thickness of the concrete pouring method does not exceed 500 mm.

[0019] Preferably, the design strength is 75% of the concrete compressive strength, the demolition process includes removing the connectors, rotating the retractable rods, and dismantling the formwork in stages, and the quality inspection process includes checking the slope of the construction joint, checking the protective layer of the reinforcing steel, checking the verticality and flatness of the wall, to ensure that the quality of the construction joint meets the design standards.

[0020] This invention provides a construction structure and quality control method for pile-slab walls using a reverse construction method with phased and layered casting. It has the following beneficial effects:

[0021] This invention constructs a stable formwork support system consisting of customized steel formwork, adjustable support poles, and horizontal connecting rods, enabling the reverse-construction pile-slab wall to possess higher overall rigidity and resistance to lateral deformation during the formwork stage. Regularly pre-drilled holes on the formwork, combined with laser measurement and calibration technology, ensure that the rebar perforation positions are consistent with the design dimensions, and that the rebar protective layer thickness remains stable within a controllable range, reducing the risk of structural weakening due to rebar misalignment. Digital rebar tying equipment enables rebar positioning and adjustment, improving rebar installation accuracy and providing reliable conditions for the subsequent concrete pouring to form a uniform and stable load-bearing structure.

[0022] This method of constructing a pile-slab wall using a phased, layered pouring technique employs a phased, layered pouring process that combines pumped concrete with an immersion vibrator. This ensures stable delivery and thorough compaction of the concrete during pouring, resulting in tight bonding between each layer and minimizing voids, cold joints, or segregation. Once the concrete reaches 75% of its design strength, the formwork support system is dismantled in a safe sequence, preventing disturbance to the formed concrete structure. Standardized checks on the slope, verticality, and flatness of construction joints ensure straight, dense, and reliable joint formation, resulting in a stable overall appearance and structural performance. This enhances the durability, safety, and construction quality of the reverse-construction pile-slab wall structure. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the reverse construction method for pile-slab wall structure;

[0024] Figure 2 A flowchart of the quality control method;

[0025] Figure 3 Elevation and section diagram of the adjustable steel support system for the reverse construction pile-slab wall formwork;

[0026] Figure 4 Detailed drawing of the connection node between the adjustable steel support upright and the horizontal tie rod;

[0027] Figure 5 A schematic diagram showing the customized steel formwork and hole layout for the horizontal construction joint of the pile-slab wall using the reverse construction method. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] like Figure 1-5 As shown, this embodiment of the invention provides a reverse-construction pile-slab wall structure for multi-stage, layered casting, including a formwork support system. The formwork support system includes a customized steel formwork and adjustable support poles. The customized steel formwork has pre-drilled holes for passing reinforcing bars. The top of the adjustable support poles is detachably connected to the customized steel formwork via rigid connectors. The pre-drilled holes have a diameter of 20mm and a center-to-center distance of 185mm × 150mm. The adjustable support poles employ a threaded rotation adjustment mechanism. The rigid connectors include wedge-shaped locking blocks and double clamps with pin holes. The adjustment range of the threaded rotation adjustment mechanism is 450-700mm.

[0031] Customized steel formwork: Shapes the wall panels and provides stable support for concrete pouring. Each formwork panel has pre-drilled holes for the reinforcing bars to pass through, ensuring accurate bar positioning and formwork compatibility. Specific requirements are as follows:

[0032] Hole diameter: Each reserved hole has a diameter of 20mm to ensure that the reinforcing bars can pass through the formwork accurately without affecting the strength of the formwork. Hole center distance: The hole center distance is designed to be 185mm × 150mm to meet the requirements for bidirectional arrangement of reinforcing bars.

[0033] Adjustable support poles: Used to provide longitudinal support for the formwork. The top of the pole is fixed to the customized steel formwork via a detachable connector, and the support height is adjusted by a threaded rotation mechanism. Specific structural parameters are as follows:

[0034] Threaded rotation adjustment mechanism: The adjustment range of the support pole is 450mm to 700mm. Rotation adjustment allows for precise control of the formwork support height. Support height adjustment: The overall formwork system height is controlled within the range of 650mm to 900mm to ensure a stable height in the contact area between the formwork and the concrete.

[0035] The adjustable screw support allows for adjustment of the template support's precision via a screw mechanism. Specific parameters regarding the structure and connection method of the adjustable screw support are as follows:

[0036] Spiral component length: The central spiral component of the adjustable spiral support is approximately 300mm long, used to adjust the support's precision. Bolted connection: The center distance between the holes at the upper and lower bolt connections is 75mm, with an elongation of 125mm, ensuring a stable connection. Support connectors: The adjustable spiral support is connected to the formwork and support legs using M20 bolts or pins. The connector steel plate is 5mm thick and has a cross-sectional width of 50mm, ensuring structural stability under high-strength conditions. Connection stabilization system: The connection stabilization system includes horizontal connecting rods, which connect the adjustable support uprights into a unified support system via disc-lock joints.

[0037] A quality control method for a pile-slab wall construction structure constructed using the reverse construction method with phased and layered casting includes:

[0038] S1. A joint review and technical briefing of the construction drawings will be conducted to develop a formwork support system. This review and technical briefing includes detailed design of the floor plans and 3D modeling. The detailed design of the floor plans will be done using CAD, while the 3D modeling will utilize BIM technology.

[0039] Construction site measurement data was imported into the BIM software platform, with pile location coordinate errors controlled within ±5mm and ground elevation data accuracy controlled within ±3mm. A solid model of the slab wall was created based on the construction drawings, with the wall thickness set at 250mm and the height built in layers of 2000mm per pour. Reinforcing steel reinforcement holes were arranged in the model with a center-to-center spacing of 185mm × 150mm, and the hole diameter was set at 20mm. The wall reinforcement adopted a double-layer, bidirectional arrangement, with the steel diameter and spacing input according to the design. The protective layer thickness was set at 25mm in the model, and the compliance of the protective layer requirements could be verified using sectioning and collision checking tools.

[0040] Based on the template system parameters, a template support system was established in the BIM model, including customized steel templates, rectangular steel pipe back braces, and adjustable support uprights. By setting elevation control lines on the template surface, elevation differences after template installation were simulated, and the elevation analysis function of the BIM software was used to ensure that the elevation error of the top surface of the template did not exceed ±3mm. A load-bearing system was established with an upright spacing of 900mm × 300mm, and the support spacing was checked to verify whether there was any interference between the template and the uprights.

[0041] Collision analysis is performed on the center of the formwork openings and the actual position of the reinforcing bars within the BIM model. It is required that the center deviation of all reinforcing bars and the reserved openings does not exceed ±2mm. For openings with deviations exceeding the limit, the formwork layout is directly adjusted through the BIM model, and then the processing drawing is generated to ensure that the formwork processing dimensions are consistent with the construction requirements.

[0042] S2. The formwork support system is installed and debugged to form the support installation system. The installation and debugging process includes mechanical hoisting and manual assembly. Mechanical hoisting uses automated hoisting equipment to hoist and position the formwork support system to form the initial hoisting positioning structure. Manual assembly is used to fine-tune and fix the initial hoisting positioning structure to form the support installation system.

[0043] S3. Based on the pre-reserved holes in the support installation system, the reinforcing bars are positioned to form a reinforcing bar binding system. The positioning process uses a laser scanning system and digital reinforcing bar binding equipment. The laser scanning system measures the pre-reserved holes, including 3D point cloud data acquisition and comparison with design drawings, to ensure that the reinforcing bars are placed in the preset positions. After the measurement process, the digital reinforcing bar binding equipment dynamically adjusts the placement position of the reinforcing bars to form the reinforcing bar binding system.

[0044] S4. Based on the support installation system and rebar tying system, concrete is poured in multiple layers to form a slab wall concrete structure. The multiple-layer pouring method includes pumped concrete pouring and immersion vibrator compaction. Pumped concrete pouring ensures uniform distribution of the concrete, while immersion vibrator compaction ensures thorough compaction. The combined effect of uniform distribution and compaction forms the slab wall concrete structure. The height of a single pour does not exceed 2 meters, and the thickness of each layer does not exceed 500 mm.

[0045] S5. After the concrete structure of the wall panel reaches its design strength, the formwork support system is dismantled, forming a construction joint structure. The construction joint structure is then inspected for quality. The design strength is 75% of the concrete compressive strength. Dismantling includes removing connectors, rotating the formwork, and dismantling the formwork in stages. Quality inspection includes checking the construction joint slope, the concrete cover of the reinforcing steel, the verticality of the wall, and the flatness of the wall, ensuring that the construction joint quality meets the design standards.

[0046] Example 2

[0047] This embodiment uses a support installation system and a rebar tying system to pour the pile-slab wall structure in stages and layers, forming a concrete slab wall entity that meets the design requirements.

[0048] 1. Pre-pouring inspection

[0049] Before pouring concrete, the formwork, supports, reinforcing bars, and embedded parts must be checked item by item, including the formwork surface elevation (allowable deviation ±3mm), the reinforcing bar protective layer thickness (allowable deviation ±3mm), and the position of embedded parts (allowable deviation not exceeding ±5mm). The inspection results must be filed in the form of a record sheet before pouring can proceed.

[0050] 2. Multi-stage and layered pouring process

[0051] 2.1 Single Pouring Height Control

[0052] The height of each concrete pour should be controlled within 2m. The first pour should be 0-2m high, and the second layer and the lintel concrete should be poured after the first layer of concrete has reached the required strength.

[0053] 2.2 Layer Thickness Setting

[0054] The concrete is poured in 500mm thick layers. Each layer of concrete must be fully vibrated and compacted to ensure good interlayer bonding.

[0055] 3. Pumped concrete is delivered and distributed evenly.

[0056] Maintain a safe distance of 300–500 mm between the pump pipe outlet and the side formwork to ensure that the free fall height of the concrete does not exceed 2 m. When the drop at the pouring location exceeds 2 m, use a 200 mm diameter tremie pipe or a lined chute to prevent segregation. Maintain the pumping pressure at 6–8 MPa and control the conveying speed at 1.5–2.0 m / s². 3 The pumping speed is maintained at a certain rate to ensure uniform concrete distribution and reduce the risk of pipe blockage. After pumping is completed, a scraper is used to initially level the surface.

[0057] 4. Compacting treatment of immersion vibrator

[0058] Use a vibrator with a diameter of 50mm and a vibration frequency of 120–150Hz. The insertion method and spacing of the vibrator should be performed according to the following parameters:

[0059] The horizontal movement interval should not exceed 1.5 times the effective radius of the vibrator, approximately 250–300 mm. Maintain a distance of 50–100 mm from the side formwork. Insert the vibrator into the lower layer of concrete each time to a depth of 50–100 mm to eliminate interlayer voids. Vibrate each point for 8–12 seconds, until the concrete stops settling, no air bubbles appear on the surface, and a layer of cement paste forms. The vibrator should be pulled out smoothly over 2–3 seconds to reduce the risk of voids. During vibration, it is strictly forbidden for the vibrator to collide with reinforcing bars, formwork, or embedded parts.

[0060] After pouring, a designated person shall be responsible for curing. All exposed surfaces shall be fully covered with a waterproof membrane. During the curing period, visible condensation should be maintained inside the membrane to keep it moist. The curing time shall be no less than 7 days, and shall be appropriately extended when the construction temperature is below 10℃.

[0061] 5. Verification of pouring effect

[0062] After pouring and initial curing are completed, the quality of the concrete is verified by the following indicators:

[0063] Table 1: Casting verification indicators and testing methods.

[0064] Inspection items Allowable deviation Detection method Construction joint slope ±5mm Leveling instrument verification Reinforcement cover thickness ±3mm Measuring with a tape measure Verticality of the wall panel ±3mm Straightedge inspection Flatness of the panel wall ±5mm Appearance quality inspection Concrete density No obvious honeycomb texture Reflects the effect of vibration

[0065] Example 3

[0066] This embodiment ensures the quality of the construction joint structure by testing the concrete strength and dismantling the formwork support system in stages. It also checks the slope of the construction joint, the protective layer of the reinforcing steel, the verticality and flatness of the wall to ensure that the quality of the construction joint meets the design standards.

[0067] 1. Strength confirmation before demolition

[0068] Concrete strength was confirmed to be 75% of its design strength using a rebound hammer test or by testing test blocks cured under the same conditions. When site conditions prevent strength testing, the demolition time was determined based on the average daytime and nighttime temperatures during construction.

[0069] When the average temperature is around 10℃, the formwork can be removed after 48 hours of standing. When the average temperature is around 15℃, the formwork can be removed after 36 hours of standing. The concrete surface is considered ready for removal when it does not feel noticeably sandy or damp to the touch and when finger pressure leaves no indentation.

[0070] 2. Dismantling and handling of the formwork support system

[0071] The formwork removal operation shall be carried out from bottom to top and in stages. It is strictly forbidden to break, knock or pry, so as not to affect the quality of the construction joint.

[0072] 2.1 Remove horizontal connecting parts

[0073] Use a torque wrench to remove the horizontal connectors one by one, controlling the torque within the range of 60–80 N·m to avoid deformation of the connectors and affecting their reuse.

[0074] 2.1 Rotating the retractor rod to unload

[0075] By rotating the central spiral component of the adjustable support, the support length is gradually shortened by 10–15 mm, allowing for segmented unloading and preventing sudden changes in localized stress in the concrete caused by one-time unloading.

[0076] 2.3 Removal of support legs, support rods, and wooden pads

[0077] During the dismantling process, temporary supports are set up on the outside of the steel formwork, with 2-3 support points set up for each section to prevent the formwork from slipping before it is completely unloaded.

[0078] 2.4 Removal of the steel formwork body

[0079] When removing the formwork, it is strictly forbidden to use a pry bar to pry it off. Instead, use a rubber mallet to tap the connecting joints to loosen them before demolding. The removed formwork should be cleaned immediately, and the residual mortar thickness should not exceed 1mm to ensure flatness and accuracy during subsequent reuse.

[0080] 3. Construction joint structural quality inspection

[0081] After the formwork is removed and a construction joint is formed, the construction joint structure is inspected according to the quality standards. The inspection items are as follows:

[0082] Table 2: Construction joint structure inspection standards and methods.

[0083] Inspection items Allowable deviation Inspection methods Construction joint horizontal slope ±5mm Leveling instrument, leveling rod Reinforcement cover thickness ±3mm Measuring with a tape measure Wall verticality ±3mm straightedge Wall flatness ±5mm straightedge, feeler gauge Reserved steel bar length ≥35d Measuring with a tape measure Waist beam external dimensions ±5mm Measuring with a tape measure Apparent cracks 0.2mm Crack width tester Visual quality good observe

[0084] During the inspection, measurements were taken for every 2m section of construction and recorded in the inspection log.

[0085] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A pile-slab wall construction structure using a reverse construction method with phased and layered casting, characterized in that, include: A template support system, comprising a customized steel template and adjustable support poles, wherein the customized steel template has reserved holes for passing through reinforcing bars, and the top of the adjustable support poles is detachably connected to the customized steel template via rigid connectors; A connection stabilization system is provided, which includes a horizontal connecting rod that connects the adjustable support uprights into an integral support system via a disc buckle connector.

2. The pile-slab wall construction structure constructed by the reverse construction method of multi-stage and layered casting according to claim 1, characterized in that: The diameter of the reserved hole is 20mm and the center-to-center distance is 185mm×150mm. The adjustable support pole adopts a threaded rotation adjustment mechanism. The rigid connector includes a wedge-shaped locking block and a double clamp with a pin hole. The adjustment range of the threaded rotation adjustment mechanism is 450-700mm.

3. A quality control method for a pile-slab wall construction structure constructed using the reverse construction method with phased and layered casting, characterized in that: S1. Conduct a joint review and technical briefing on the construction drawings to form a template support system. The joint review and technical briefing includes detailed design of the plan drawings and three-dimensional modeling design. S2. The template support system is installed and debugged to form a support installation system. The installation and debugging process includes mechanical hoisting and manual assembly. S3. The reinforcing bars are positioned based on the reserved holes of the bracket installation system, and a reinforcing bar binding system is formed through the positioning process. The positioning process adopts a laser scanning system and a digital reinforcing bar binding device. S4. Based on the bracket installation system and the rebar tying system, the concrete is poured in stages and layers to form a slab wall concrete structure. The staged pouring process is carried out by concrete pouring. S5. After the concrete structure of the wall panel reaches the design strength, the formwork support system is dismantled, and a construction joint structure is formed based on the dismantling process. The construction joint structure is then subjected to quality inspection.

4. The quality control method for a pile-slab wall construction structure constructed using the reverse construction method with phased and layered casting as described in claim 3, characterized in that: The detailed design of the 2D drawings is done using CAD, and the 3D modeling design is done using BIM technology.

5. The quality control method for a pile-slab wall construction structure constructed using the reverse construction method with phased and layered casting as described in claim 3, characterized in that: The mechanical hoisting uses automated hoisting equipment, which hoists and positions the template support system to form a preliminary hoisting and positioning structure. The manual assembly then fine-tunes and fixes the preliminary hoisting and positioning structure to form the support installation system.

6. The quality control method for a pile-slab wall construction structure constructed using the reverse construction method with phased and layered casting as described in claim 3, characterized in that: The laser scanning system measures the reserved hole, and the measurement process includes three-dimensional point cloud data acquisition and design drawing comparison. After the measurement process, the digital rebar binding equipment dynamically adjusts the placement position of the rebar, and the rebar binding system is formed by the dynamic adjustment of the placement position.

7. The quality control method for a pile-slab wall construction structure constructed using the reverse construction method with phased and layered casting as described in claim 3, characterized in that: The concrete pouring method includes pumped concrete pouring and immersion vibrator compaction. The pumped concrete pouring uniformly delivers and distributes the concrete, while the immersion vibrator compaction compacts the concrete. The synergistic effect of uniform delivery and compaction forms the concrete structure of the slab wall.

8. The quality control method for a pile-slab wall construction structure constructed using the reverse construction method with phased and layered casting as described in claim 3, characterized in that: The single pouring height of the concrete pouring method shall not exceed 2 meters, and the layer thickness of the concrete pouring method shall not exceed 500 mm.

9. The quality control method for a pile-slab wall construction structure constructed using the reverse construction method with phased and layered casting as described in claim 3, characterized in that: The design strength is 75% of the concrete compressive strength. The demolition process includes removing connectors, rotating the retractable rod, and dismantling the formwork in stages. The quality inspection process includes checking the slope of the construction joint, checking the concrete cover of the reinforcing steel, checking the verticality and flatness of the wall.

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