Large-diameter thin-wall steel ring wall back concrete compaction pouring construction method

Abstract

This invention discloses a method for dense concrete pouring behind a large-diameter thin-walled steel ring, belonging to the field of underground engineering lining construction technology. This invention utilizes prefabricated steel sheets in a factory and assembles them with high precision inside the tunnel, constructing a collaborative system of "active adjustment of internal support + rigid fixing of external support." It employs a permanent, fine-mesh flexible end mold, symmetrically pouring concrete in layers: the bottom layer, sidewall layer, and arch top layer. Combined with dynamic deformation monitoring and hydraulic closed-loop control throughout the process, the concrete pouring and cyclic construction are ultimately completed. This invention effectively ensures concrete density, suppresses deformation during steel ring construction, improves the impermeability of construction joints, and offers high construction precision and efficiency. It is suitable for steel-concrete composite lining construction in high-pressure underground gas storage chambers with working pressures exceeding 10 MPa and is highly reproducible.

Description

Technical Field

[0001] This invention relates to the field of underground engineering lining construction technology, and in particular to a method for dense concrete pouring behind a large-diameter thin-walled steel ring wall. Background Technology

[0002] In large-scale underground gas storage tunnel projects, large-diameter (usually inner diameter ≥ 10m) thin-walled (wall thickness generally ≤ 30mm) steel rings are often used as the inner lining structure, behind which concrete needs to be poured to form a composite lining system. This type of structure is characterized by its large diameter, thin walls, high pressure resistance, and stringent sealing requirements, and its concrete pouring construction faces numerous technical challenges. The compactness of the concrete pouring is difficult to guarantee. Due to the large diameter and long circumference of the steel ring, the concrete is prone to segregation and bleeding during pumping, resulting in gaps or voids between the steel ring and the concrete. This seriously affects the structural integrity and bearing capacity, especially the voids at the top of the arch. The steel ring is also prone to deformation during pouring. The thin-walled steel ring itself has low stiffness and is easily deformed, ellipticized, or buckled locally under the lateral pressure of the concrete, its own weight, and construction loads. This directly affects the geometric accuracy of the structure and its long-term safe operation. The pouring process is poorly controllable. Traditional integral pouring or simple layered pouring methods are difficult to effectively control the pouring speed, symmetry, temperature, and deformation, which can easily lead to quality defects such as cold joints and stress concentration. End sealing and construction joint treatment are difficult. The sealing of large-diameter circumferential construction joints usually uses traditional steel formwork, which has problems such as difficulty in demolding and poor interface treatment. This can easily form leakage channels and fail to meet the sealing requirements of high-pressure gas storage caverns.

[0003] Existing technologies often employ methods such as increasing concrete fluidity, external reinforcement, or segmented casting to address these issues. However, these methods suffer from drawbacks such as low construction efficiency, high cost, and insufficient quality control. Especially for high-pressure gas storage caverns with operating pressures exceeding 10 MPa, the requirements for the compactness, integrity, and impermeability of the lining structure are extremely high, making it difficult for traditional methods to meet actual engineering needs. Summary of the Invention

[0004] The purpose of this invention is to provide a method for dense concrete pouring behind a large-diameter thin-walled steel ring. This method can effectively ensure the density of the concrete pouring, suppress the deformation of the steel ring during pouring, improve the controllability of the construction process, and improve the quality of the construction joint, thus meeting the engineering requirements of high-pressure underground gas storage chambers.

[0005] To achieve the above objectives, the present invention provides a method for dense concrete pouring behind a large-diameter thin-walled steel ring wall, comprising the following steps: S1. The factory prefabricates arc-shaped steel tiles in sections and performs anti-corrosion treatment. The steel tiles are then transported to the assembly station via an internal track. A magnetic manipulator and hydraulic struts are used to complete high-precision assembly and longitudinal seam welding to form standard pipe sections. Multiple standard pipe sections are then welded together to form a large pipe section, which is then transported to the pouring station. S2. An adjustable hydraulic inner support frame is installed inside the steel ring to actively constrain the deformation of the steel ring and provide a working platform. A rigid outer support is set on the outside of the steel ring along the circumferential direction to provide fixed constraints, forming an internal and external coordinated stable system. S3. Install a permanent, non-removable flexible end formwork consisting of a steel reinforcement cage and a fine wire mesh at the end of the pouring section; S4. Divide the concrete pouring section into bottom layer, side wall layer and arch top layer, and pour them in sequence according to the principle of left-right symmetry and horizontal layering. Each layer should be poured after the previous layer of concrete has initially set. S5. Set up monitoring points at key parts of the steel ring to collect deformation data of the steel ring in real time, and dynamically adjust the supporting force of the inner support frame according to the monitoring results; S6. After the concrete has been poured, it shall be kept warm and moist. Once the concrete has reached the design strength, the internal support system shall be removed, and the flexible end formwork shall be permanently retained before proceeding to the next pouring section.

[0006] Preferably, the adjustable hydraulic inner support frame in step S2 consists of a central column, multiple radial support rods, an arc-shaped top plate, and multiple horizontal working platforms. The arc-shaped top plate is connected to the top of the support rods through hydraulic cylinders, and the roundness of the steel ring is finely adjusted in real time through the hydraulic system.

[0007] Preferably, the rigid external support in step S2 is an I-beam, with one end of the I-beam welded to the stiffening ring of the steel ring, and the other end anchored to the surrounding rock or the surface of the initial support by an expansion anchor bolt.

[0008] Preferably, in step S3, the fine wire mesh has a mesh size of 6-10mm and a wire diameter of 0.8-1.2mm. It is tied and fixed to the reinforcing steel frame with stainless steel cable ties in a quincunx pattern. The edges of the wire mesh are spot-welded to the steel ring stiffening ring and sealed to the initial support surface with nails.

[0009] Preferably, in step S4, the pouring height is divided based on the tunnel diameter D, with the bottom layer pouring height being approximately D / 6, the sidewall layer pouring height being approximately D / 2, and the remaining height being the arch top layer.

[0010] Preferably, in step S4, the thickness of the pouring layer on the same side is strictly controlled to be ≤0.5m, the height difference between the pouring surfaces on the left and right sides is ≤0.5m, and a multi-point uniform material distribution method is adopted.

[0011] Preferably, in step S4, the pumping speed is reduced when pouring the top layer of the arch, the fullness of the concrete filling is judged by the overflow of the slurry through the vent holes reserved in the arch, and grouting pipes are pre-embedded in the arch for later supplementary grouting.

[0012] Preferably, the monitoring point in step S5 is a reflective sheet pasted on the stiffening ring of the steel ring, and a total station is used for real-time monitoring. The regular monitoring frequency during the pouring period is once every 30 minutes, and the frequency is increased to once every 15 minutes during the high-speed pumping stage.

[0013] Preferably, in step S5, when the radial displacement of the steel ring exceeds the warning allowable value, the extension and retraction of the hydraulic cylinder at the top of the support rod in the corresponding area is adjusted through the internal support hydraulic control system to perform local jacking correction.

[0014] Preferably, the large-diameter thin-walled steel ring is a steel ring with an inner diameter ≥10m and a wall thickness ≤30mm.

[0015] Therefore, the present invention employs the above-mentioned method for dense concrete pouring behind a large-diameter thin-walled steel ring wall, which has the following technical advantages: (1) The present invention adopts a layered symmetrical pouring process, which effectively avoids concrete segregation and unilateral pressure imbalance; combined with the micro-permeability of the flexible end mold, a natural rough surface is formed, eliminating construction cold joints and arch voids, and ensuring the overall compactness of the concrete.

[0016] (2) The present invention constructs a collaborative stability system of active adjustment of internal support + rigid fixation of external support. Combined with dynamic deformation monitoring throughout the process and closed-loop control of hydraulic system, it can correct radial deformation, ellipticization and local buckling of steel ring in real time and control construction deformation within the allowable range.

[0017] (3) The present invention is equipped with special tooling such as a track transport trolley and a circular platform trolley, and has formulated clear process parameters and standardized construction procedures, which realizes precise control of key indicators such as pouring speed, symmetry and deformation, and greatly improves construction accuracy and efficiency.

[0018] (4) The present invention uses a fine wire mesh flexible end mold, which achieves no disassembly, self-roughening, and grout leakage prevention. It is permanently left at the construction joint as a reinforcing interface, effectively preventing the formation of leakage channels.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Fig. 1 This is a flowchart illustrating the overall process of a method for dense concrete pouring behind a large-diameter thin-walled steel ring wall according to the present invention. Fig. 2This is a schematic diagram of the inner support structure of the steel ring in the construction method for dense concrete pouring behind a large-diameter thin-walled steel ring according to the present invention. Fig. 3 This is a schematic diagram of the inner and outer support coordination system of the steel ring in the construction method for dense concrete pouring behind a large-diameter thin-walled steel ring according to the present invention. Fig. 4 This is a detailed diagram of the flexible fine wire mesh end mold structure in the construction method of dense concrete pouring behind a large-diameter thin-walled steel ring wall according to the present invention.

[0021] Figure Labels 1. Tunnel wall; 2. Steel ring; 3. External support; 4. Arched roof plate; 5. Hydraulic cylinder; 6. Annular stiffening plate; 7. Support rod; 8. Wire mesh plug; 9. Reinforcing steel skeleton. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0024] Example 1 This embodiment takes an underground gas storage cavern project as an example. The steel lining of the project is a thin-walled ring made of steel plate with an inner diameter of 15m (i.e., D=15m) and a wall thickness of 22mm. The designed casting section length is 9m (made of 3 sections of 3m long single rings welded together). Self-compacting fiber concrete needs to be poured on the outside of the steel lining to form a composite lining. The working pressure exceeds 10Mpa.

[0025] like Figs. 1 to 4 As shown, a method for constructing a large-diameter thin-walled steel ring with dense concrete pouring includes the following steps: S1. The internal assembly and positioning of the steel ring. Pre-fabricated single-section curved steel tiles are transported to the assembly platform inside the tunnel via a rail transport trolley. The assembly platform is then activated, and four sets of magnetic manipulators and hydraulic struts on its circular frame sequentially grab and adhere four tiles. The control system adjusts the strut length to the designed radius of 7.5m, precisely positioning the tiles into a circle. Four longitudinal welds are then performed using submerged arc welding, followed by weld quality inspection. The welded single ring (3m long) is transported to the assembly area via a transport trolley, where it is welded to two other rings to form a 9m long large pipe section. After passing inspection, it is transferred to the pouring station.

[0026] S2. Coordinated installation of internal and external support systems First, the internal support system is installed: The intelligent internal support frame is pre-assembled at the assembly site. This frame consists of a central column, eight radial support rods 7 (Φ180×3.5mm), and an arc-shaped top plate 4 at the ends. The support rods 7 and the arc-shaped top plate 4 are connected by hydraulic cylinders 5. Two construction platforms are provided at the top. The assembled internal support frame is then hoisted onto a rail transport trolley and transported into the pre-positioned 9m long steel ring 2. The hydraulic system is activated, causing the output ends of the hydraulic cylinders 5 at the top of the eight support rods 7 to extend at a uniform speed until the arc-shaped top plate 4 makes uniform contact with the inner wall of the steel ring 2. The initial support force is preset to 30% of the design value.

[0027] After the internal support is completed, the external support system is installed: I16 I-beams are welded along the circumferential direction at the position of the annular stiffening plate 6 on the outside of the steel ring 2 to serve as radial external supports 3. Six I-beams are arranged at the top, 12 on each side of the middle, and six at the bottom. The other end of the I-beams is reliably connected to the tunnel wall 1 (surrounding rock) via expansion bolts and fully welded to the annular stiffening plate 6 of the steel ring 2, forming a rigid external support network. The internal support system mainly provides active radial constraint and roundness adjustment capability, while the external support system provides fixed axial and circumferential stability; together, they constitute a stable system.

[0028] S3. Construction of Flexible End Formwork System At the starting end of the 9m long pouring section, external support 3 I-beams are used as the vertical main keel, and Φ22 steel bars are welded as circumferential distribution bars (spaced 200mm) to form a "well"-shaped steel reinforcement skeleton 9. A plug-in wire mesh 8 is used as the permanent end formwork, preferably hot-dip galvanized fine wire mesh with an 8mm mesh size and a 1.0mm wire diameter. The wire mesh is laid tightly against the steel reinforcement skeleton 9 and secured with stainless steel cable ties in a 150mm×150mm staggered pattern to ensure the mesh surface is taut and flat. The edges of the wire mesh are spot-welded to the annular stiffening plate 6 of the steel ring 2, and fixed with nails at the contact points with the tunnel wall 1 (initial support face) to achieve a seal. Before pouring, clean water is sprayed into the mesh, and no continuous water dripping is observed on the outside to confirm a good seal. This end formwork will be retained as part of the permanent structure.

[0029] S4. Layered symmetrical dense concrete pouring A high-pressure vehicle-mounted pump, in conjunction with wear-resistant pump pipes, was used for pouring, and the concrete was poured in three layers in sequence: the bottom layer, the sidewall layer, and the top arch layer. First layer (bottom layer) pouring: The pouring height is 2.5m (approximately D / 6). The pump pipe outlet splits into two branches via a tee, aligning with the pouring points on the left and right sides of the bottom of the steel ring, respectively. Pouring begins approximately 0.5m from the left side. 3 After pouring approximately 50cm thick concrete, immediately switch to the symmetrical position on the right and pour an equal amount of concrete. Continue alternating between left and right, advancing horizontally in layers. Strictly control the height difference between pouring layers on the same side to ≤0.5m, and the height difference between the pouring surfaces on the left and right sides to ≤0.5m. This layer's pouring took approximately 4 hours. Second layer (sidewall layer) pouring: Begin pouring after the first layer of concrete has initially set (approximately 6 hours later), with a pouring height of 7.5m (approximately D / 2), and a cumulative pouring height of 10m. Adjust the pump pipe to the reserved pouring port above the sidewall, continuing the principle of "left-right symmetry and horizontal layering". Strengthen vibration, paying special attention to the corners of the formwork and areas with dense reinforcement; The third layer (arch top layer) pouring: Begin after the second layer has initially set, pouring the remaining height to the arch top. During arch top pouring, slow down the pumping speed and observe the overflow from the pre-reserved vent holes as a basis for determining if the arch is full. After pouring, pre-embed grouting pipes in the arch top for supplementary grouting if necessary later.

[0030] Throughout the pouring process, the material is distributed evenly at multiple points through the distribution pipe at the end of the pump pipe to avoid direct impact on the steel ring or reinforcing bars.

[0031] S5. Dynamic Deformation Monitoring and Control Throughout the Entire Process Twelve reflective plates were attached as monitoring points to the top, waist, and bottom annular stiffening plates 6 of the front, middle, and rear sections of the 9m long steel ring. During the pouring process, a high-precision total station was used for automated monitoring. The normal monitoring frequency was once every 30 minutes, which was increased to once every 15 minutes when the pumping speed was the fastest.

[0032] When the second layer of sidewall was poured to a height of 5m, the top monitoring point J1 displaced 8mm into the hole (the warning value is 10mm), and the displacement rate accelerated. The cause of the anomaly was immediately analyzed and control measures were initiated: via the control box of the internal support system, the hydraulic cylinder 5 at the top of the corresponding support rod 7 was slightly retracted, and the support force of the waist support rod was slightly increased. After the operation, the area was left to stand for 10 minutes. Monitoring the data for the next cycle showed that the displacement of point J1 gradually decreased and stabilized within 5mm, and normal construction continued.

[0033] S6. Curing and Cyclic Construction: After pouring, the concrete shall be kept warm and moist for at least 14 days. Once the concrete has reached its design strength, the internal support system shall be removed sequentially. The flexible wire mesh end formwork shall be permanently left at the construction joint to form an excellent interface. Then, the next cycle (the next 9m segment) of construction shall commence.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for constructing a large-diameter thin-walled steel ring with dense concrete pouring, characterized in that, Includes the following steps: S1. The factory prefabricates arc-shaped steel tiles in sections and performs anti-corrosion treatment. The steel tiles are then transported to the assembly station via an internal track. A magnetic robotic arm and hydraulic struts are used to complete the assembly and longitudinal seam welding to form standard pipe sections. Multiple standard pipe sections are then welded together to form a large pipe section, which is then transported to the pouring station. S2. An adjustable hydraulic inner support frame is installed inside the steel ring to actively constrain the deformation of the steel ring and provide a working platform. A rigid outer support is set on the outside of the steel ring along the circumferential direction to provide fixed constraints, forming an internal and external coordinated stable system. S3. Install a permanent, non-removable flexible end formwork consisting of a steel reinforcement cage and a fine wire mesh at the end of the pouring section; S4. Divide the concrete pouring section into bottom layer, side wall layer and arch top layer, and pour them in sequence according to the principle of left-right symmetry and horizontal layering. Each layer should be poured after the previous layer of concrete has initially set. S5. Set up monitoring points at key parts of the steel ring to collect deformation data of the steel ring in real time, and dynamically adjust the supporting force of the inner support frame according to the monitoring results; S6. After the concrete has been poured, it shall be kept warm and moist. Once the concrete has reached the design strength, the internal support system shall be removed, and the flexible end formwork shall be permanently retained before proceeding to the next pouring section.

2. The method for dense concrete pouring behind a large-diameter thin-walled steel ring wall according to claim 1, characterized in that: The adjustable hydraulic inner support frame described in step S2 consists of a central column, multiple radial support rods, an arc-shaped top plate, and multiple horizontal working platforms. The support rods are connected to the arc-shaped top plate through hydraulic cylinders, and the roundness of the steel ring is finely adjusted in real time through the hydraulic system.

3. The method for dense concrete pouring behind a large-diameter thin-walled steel ring wall according to claim 1, characterized in that: The rigid external support mentioned in step S2 is made of I-beams. One end of the I-beam is welded to the stiffening ring of the steel ring, and the other end is anchored to the surrounding rock or the surface of the initial support by expansion anchors.

4. The method for dense concrete pouring behind a large-diameter thin-walled steel ring wall according to claim 1, characterized in that: The fine wire mesh described in step S3 has a mesh size of 6-10mm and a wire diameter of 0.8-1.2mm. It is tied and fixed to the reinforcing steel frame with stainless steel cable ties in a quincunx pattern. The edges of the wire mesh are spot-welded to the steel ring stiffening ring and sealed to the initial support surface with nails.

5. The method for dense concrete pouring behind a large-diameter thin-walled steel ring wall according to claim 1, characterized in that: In step S4, the pouring height is divided based on the tunnel diameter D. The pouring height of the bottom layer is D / 6, the pouring height of the sidewall layer is D / 2, and the remaining height is the top arch layer.

6. The method for dense concrete pouring behind a large-diameter thin-walled steel ring wall according to claim 1, characterized in that: In step S4, the pouring process strictly controls the thickness of the pouring layer on the same side to be ≤0.5m and the height difference between the pouring surfaces on the left and right sides to be ≤0.5m, and adopts a multi-point uniform material distribution method.

7. The method for dense concrete pouring behind a large-diameter thin-walled steel ring wall according to claim 1, characterized in that: In step S4, the pumping speed is reduced when pouring the top layer of the arch. The fullness of the concrete filling is judged by the overflow of the grout through the vent holes reserved in the arch top. Grouting pipes are pre-embedded in the arch top for later supplementary grouting.

8. The method for dense concrete pouring behind a large-diameter thin-walled steel ring wall according to claim 1, characterized in that: The monitoring point mentioned in step S5 is a reflective sheet pasted on the stiffening ring of the steel ring. A total station is used for real-time monitoring. The regular monitoring frequency during the pouring period is once every 30 minutes, and the frequency is increased to once every 15 minutes during the high-speed pumping stage.

9. The method for dense concrete pouring behind a large-diameter thin-walled steel ring wall according to claim 1, characterized in that: In step S5, when the radial displacement of the steel ring exceeds the warning allowable value, the extension and retraction of the hydraulic cylinder at the top of the support rod in the corresponding area is adjusted through the internal support hydraulic control system to perform local jacking correction.

10. The method for dense concrete pouring behind a large-diameter thin-walled steel ring wall according to claim 1, characterized in that: The large-diameter thin-walled steel ring is a steel ring with an inner diameter ≥ 10m and a wall thickness ≤ 30mm.

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