A secondary structure of an external sealing for pipe jacking construction and a construction method thereof

Abstract

This invention relates to an external secondary sealing structure and its construction method for pipe jacking construction. The structure includes a portal sealing steel plate, a water-stop curtain, a pressure plate, and a pipe section, as well as a concrete sealing body, an isolation layer, and a grouting pipe. The portal sealing steel plate is located at the portal, the water-stop curtain is located between the portal sealing steel plate and the pipe section, and the pressure plate is located outside the water-stop curtain and connected to the portal sealing steel plate to fix the water-stop curtain. The pressure plate is retractable relative to the portal sealing steel plate. The concrete sealing body is arranged around the outer periphery of the pipe section and located outside the water-stop curtain. The isolation layer is located in the adjacent area between the concrete sealing body and the pipe section, the portal sealing steel plate, and the water-stop curtain. The grouting pipe is pre-embedded in the concrete sealing body and extends to the inner side of the water-stop curtain. This invention forms an external secondary sealing and subsequent grouting reinforcement system based on the traditional primary portal sealing, thereby improving the reliability, safety, and adaptability of portal sealing during pipe jacking construction.

Description

Technical Field

[0001] This invention relates to the field of pipe jacking engineering technology, and in particular to an external sealing secondary structure for pipe jacking construction. Background Technology

[0002] In urban underground pipeline construction and tunnel crossings, pipe jacking is widely used due to its minimal disturbance to surface traffic and surrounding buildings, high construction efficiency, and strong adaptability. During pipe jacking, a sealing structure is typically installed at the tunnel portal when the pipe section is launched or received. This seals the annular gap between the portal and the pipe section, preventing groundwater, mud, and sand from entering the tunnel. In existing technologies, the portal sealing structure usually employs a "one-time sealing" method consisting of a portal sealing steel plate, a water-stop curtain, and a pressure plate. The pressure plate presses and fixes the water-stop curtain to the portal sealing steel plate, ensuring contact between the curtain and the outer circumference of the pipe section, thus achieving a basic seal.

[0003] However, traditional "primary sealing" structures are typically only suitable for construction environments with relatively stable geological conditions and low groundwater pressure. In water-rich strata, soft soil strata, or high water pressure conditions, the water-stop curtain is prone to wear and tear due to friction during pipe jacking, and the pressure plate and its connections are also prone to loosening and misalignment. This results in insufficient sealing reliability at the tunnel portal, leading to problems such as water inrush, sand inrush, construction interruption, pipe section entrapment, and equipment damage, posing significant safety hazards and quality risks. Furthermore, existing tunnel portal sealing structures lack reinforcement and sealing measures after primary sealing failure and emergency grouting channels, making it difficult to effectively address leaks in a timely manner. This increases maintenance costs and prolongs the construction period. Therefore, it is necessary to provide an external secondary sealing structure for pipe jacking construction to improve the reliability of tunnel portal sealing and construction safety. Summary of the Invention

[0004] In view of the above-mentioned defects of existing technical solutions, the main purpose of this invention is to develop an external sealing secondary structure for pipe jacking construction, so as to form an external secondary sealing and subsequent grouting reinforcement system on the basis of the traditional primary sealing of the tunnel portal, thereby improving the reliability, safety and adaptability of the tunnel portal sealing during pipe jacking construction.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: An external sealing secondary structure for pipe jacking construction includes a portal sealing steel plate, a water-stop curtain, a pressure plate, and a pipe section passing through the portal of the working shaft. It also includes a concrete sealing body, an isolation layer, and a grouting pipe. The portal sealing steel plate is located at the portal, the water-stop curtain is located between the portal sealing steel plate and the pipe section, and the pressure plate is located outside the water-stop curtain and connected to the portal sealing steel plate to fix the water-stop curtain. The pressure plate is retractable relative to the portal sealing steel plate to form a reserved space outside the portal for secondary sealing construction. The concrete sealing body is arranged around the outer periphery of the pipe section and located outside the water-stop curtain. The isolation layer is located in the adjacent area between the concrete sealing body and the pipe section, the portal sealing steel plate, and the water-stop curtain. The grouting pipe is embedded in the concrete sealing body and extends to the inner side of the water-stop curtain.

[0006] Preferably, the isolation layer includes a grease layer and a geotextile layer. The grease layer is applied to the outer surface of the jacking pipe section and the outer surface of the tunnel portal sealing steel plate. The geotextile layer is disposed around the outer periphery of the jacking pipe section and fills the chamfered area between the jacking pipe section and the waterstop curtain.

[0007] Preferably, the geotextile layer is wound around the outer periphery of the jacking pipe section to form 4-5 layers, and the width of the geotextile layer along the axial direction of the jacking pipe section is 30-50 cm.

[0008] Preferably, the pressure plate is connected to the portal sealing steel plate by bolts, and the nuts of the bolts are coated with sealant or wrapped with PTFE tape.

[0009] Preferably, the pressure plate is arranged in segments along the circumference of the jacking pipe section.

[0010] Preferably, the grouting pipes are pre-embedded in the concrete sealing body at intervals along the circumference of the jacking pipe section. The grouting pipes include at least grouting pipes located at positions 2, 4, 8 and 10 along the circumference of the jacking pipe section, and each grouting pipe is equipped with a control valve.

[0011] On the other hand, the present invention also discloses a construction method for an external sealing secondary structure for pipe jacking construction, used to form the above-mentioned external sealing secondary structure for pipe jacking construction, comprising the following steps: S1. Prepare the tunnel entrance by fixing the sealing steel plate to the working shaft entrance and installing the water-stop curtain and fixing the water-stop curtain with the pressure plate. S2, start the pipe jacking and position the first pipe section, and push the pipe section to the predetermined position outside the working shaft entrance; S3, Adjust the pressure plate to retract relative to the sealing steel plate of the tunnel entrance, so as to form a reserved space outside the working shaft entrance for secondary sealing construction; S4, perform contact surface isolation treatment, and set an isolation layer in the forming area of ​​the concrete sealing body; S5, Install the mold for forming the concrete sealing body, and pre-embed the grouting pipe in the forming area of ​​the concrete sealing body so that the grouting pipe extends to the inside of the water-stop curtain. S6, pour concrete into the mold in layers and vibrate it to form a concrete sealing body surrounding the outer periphery of the jacking pipe section; S7, the concrete sealing body is cured, and the jacking of the pipe section is resumed after the concrete sealing body reaches the predetermined strength.

[0012] Preferably, in step S3, the bolts used to connect the pressure plate and the door sealing steel plate are loosened, so that the pressure plate is retracted by 5 cm as a whole, and the bolt nuts are tightened again after retraction.

[0013] Preferably, in step S5, a mold is made according to the outer diameter of the jacking pipe section. The inner diameter of the mold is 2-3 cm larger than the outer diameter of the jacking pipe section. The grouting pipe is set at least at the 2, 4, 8 and 10 points around the jacking pipe section.

[0014] Preferably, in step S7, after the concrete sealing body is poured for 4-5 hours and the initial setting strength reaches 50% of the design value, the jacking of the pipe section is resumed. If leakage occurs later, special sealing material is injected into the inside of the water-stop curtain through the grouting pipe embedded in the concrete sealing body for reinforcement and sealing.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention, based on a primary flexible seal consisting of a portal sealing steel plate, a water-stop curtain, and a pressure plate, further incorporates a concrete sealing body encircling the outer periphery of the jacking pipe section and located outside the water-stop curtain. Simultaneously, grouting pipes are pre-embedded within the concrete sealing body, and an isolation layer is established in the adjacent areas of the concrete sealing body and the jacking pipe section, portal sealing steel plate, and water-stop curtain. This constructs a triple protection system: primary flexible sealing + secondary rigid sealing + subsequent grouting reinforcement. In this system, the water-stop curtain serves as the initial waterproof layer, the concrete sealing body forms a rigid sealing wall providing stable protection for the secondary sealing, and the grouting pipe system can reinforce and seal localized leakage areas through chemical grouting when necessary, achieving comprehensive sealing protection. This structure significantly improves the overall sealing performance and structural stability of the tunnel portal during pipe jacking construction. The retractable pressure plate provides space for secondary sealing, facilitating the formation of a stable and reliable secondary protection on the outside of the tunnel portal by the concrete sealing body. It also reduces the risk of leakage in situations such as wear and tear of the water-stop curtain, loosening or misalignment of the pressure plate. The grouting pipe is pre-embedded within the concrete sealing body and extends to the inside of the water-stop curtain, allowing for timely grouting reinforcement in case of localized leakage or abnormalities, further enhancing the safety and reliability of the tunnel portal during the jacking cycle. Furthermore, this invention reduces the risks of water inrush, sand inrush, soil erosion, and disturbance to surrounding strata, protecting the stability of surrounding buildings, minimizing damage to the geological environment, and preventing adverse impacts on traffic and residents' lives from construction hazards. Therefore, it offers significant safety, environmental, and social benefits, providing a comprehensive and highly reliable sealing solution for pipe jacking construction. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the external sealing secondary structure for pipe jacking construction of the present invention; Figure 2 This is a schematic diagram of the structure of the pressure plate and concrete sealing body of the present invention; Figure 3 This is a construction flowchart of the external sealing secondary structure for pipe jacking construction according to the present invention.

[0018] Explanation of reference numerals in the attached drawings: 1-Sealing steel plate for tunnel entrance; 2-Water-stop curtain; 3-Pressure plate; 4-Pipe jacking section; 5-Concrete sealing body; 6-Isolation layer; 61-Grease layer; 62-Geotextile layer; 7-Grouting pipe; 8-Tunnel entrance; 9-Bolt; 10-Control valve. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention belong to the present invention.

[0020] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0021] Please see Figure 1-2 This embodiment discloses an external sealing secondary structure for pipe jacking construction, including a portal sealing steel plate 1, a water-stop curtain 2, a pressure plate 3, a pipe section 4 passing through the working shaft portal 8, a concrete sealing body 5, an isolation layer 6, and a grouting pipe 7. The portal sealing steel plate 1 serves as a basic installation component set at the working shaft portal 8, providing installation support for the water-stop curtain 2 and the pressure plate 3. The pipe section 4 passes through the working shaft portal 8, and the concrete sealing body 5 is set on the outside of the portal 8 and serves as an external secondary sealing structure.

[0022] A sealing steel plate 1 is installed at the tunnel portal 8. A water-stop curtain 2 is installed between the sealing steel plate 1 and the jacking pipe section 4. The water-stop curtain 2 and the outer periphery of the jacking pipe section 4 form a flexible seal. A pressure plate 3 is installed outside the water-stop curtain 2 and connected to the sealing steel plate 1 to fix the water-stop curtain 2, thus forming a basic primary sealing structure when the jacking pipe section 4 passes through the working shaft portal 8. The pressure plate 3 can be retracted relative to the sealing steel plate 1 to form a reserved space outside the portal 8 for secondary sealing construction. Specifically, the retraction distance of the pressure plate 3 relative to the sealing steel plate 1 is 5 cm. After the pressure plate 3 is retracted, it can form an operating space outside the portal 8 for the construction of the concrete sealing body 5. It is also beneficial to arrange the isolation layer 6 and the grouting pipe 7 in this area, thus providing conditions for the formation of the external secondary sealing structure.

[0023] The concrete sealing body 5 is arranged around the outer periphery of the jacking pipe section 4 and located outside the water-stop curtain 2. As a rigid sealing structure located outside the water-stop curtain 2, the concrete sealing body 5 can further seal and reinforce the outside of the tunnel portal 8. The concrete sealing body 5 can be a reinforced concrete structure or a plain concrete structure arranged around the outer periphery of the jacking pipe section 4. An isolation layer 6 is set in the adjacent area between the concrete sealing body 5 and the jacking pipe section 4, the portal sealing steel plate 1, and the water-stop curtain 2. The grouting pipe 7 is pre-embedded in the concrete sealing body 5 and extends to the inner side of the water-stop curtain 2. The isolation layer 6 can form an isolation protection between the concrete sealing body 5 and the jacking pipe section 4, the portal sealing steel plate 1, and the water-stop curtain 2, preventing the concrete sealing body 5 from directly adhering to the surface of adjacent components and affecting the subsequent jacking of the jacking pipe section 4 or the sealing state of the water-stop curtain 2. After the grouting pipe 7 extends to the inner side of the water-stop curtain 2, the area near the water-stop curtain 2 can be reinforced and sealed by injecting grout into the grouting pipe 7 in the later stage, so that the entire structure forms a composite sealing system that combines flexible sealing, rigid sealing, and grouting reinforcement.

[0024] Furthermore, the isolation layer 6 includes a grease layer 61 and a geotextile layer 62. The grease layer 61 is applied to the outer surface of the jacking pipe section 4 and the outer surface of the tunnel portal sealing steel plate 1, which can form a lubricating isolation interface between the concrete sealing body 5 and the jacking pipe section 4 and the tunnel portal sealing steel plate 1, preventing the concrete sealing body 5 from directly bonding with the jacking pipe section 4 or the tunnel portal sealing steel plate 1. The geotextile layer 62 is set on the outer periphery of the jacking pipe section 4 and fills the chamfered area between the jacking pipe section 4 and the water-stop curtain 2, which can fill and isolate the gap therein, reduce the possibility of grout entering the adjacent area of ​​the water-stop curtain 2 during concrete pouring, and also help improve the sealing and buffering effect of the water-stop curtain 2 and the adjacent part of the jacking pipe section 4. Specifically, the geotextile layer 62 is wrapped around the outer periphery of the jacking pipe section 4 to form 4-5 layers, making the isolation and filling effect more stable. The geotextile layer 62 is set with a width of 30-50 cm along the axial direction of the jacking pipe section 4, which enables the geotextile layer 62 to form an isolation area with a certain coverage on the outer periphery of the jacking pipe section 4, thereby better meeting the isolation requirements of the concrete sealing body 5 forming area.

[0025] The pressure plate 3 is connected to the tunnel portal sealing steel plate 1 by bolts 9. Bolts 9 reliably fix the pressure plate 3 to the tunnel portal sealing steel plate 1 and facilitate loosening, retraction, and re-tightening of the pressure plate 3 according to construction needs, thereby reserving operating space for secondary sealing construction. The nuts of bolts 9 are coated with sealant or wrapped with PTFE tape, which can provide auxiliary sealing at the bolt connection point and improve the overall seepage prevention performance of the tunnel portal sealing area. The pressure plate 3 is installed in sections along the circumference of the jacking pipe section 4.

[0026] Grouting pipes 7 are pre-embedded at intervals along the circumference of the jacking pipe section 4 within the concrete sealing body 5, forming multiple grouting channels inside the concrete sealing body 5. This allows for the injection of grout through the grouting pipes 7 to reinforce the sealing body and adjacent areas in case of local leakage or abnormalities. Specifically, the grouting pipes 7 include at least grouting pipes located at positions 2, 4, 8, and 10 along the circumference of the jacking pipe section 4. Each grouting pipe 7 is equipped with a control valve 10, which allows for adjustment of the grouting volume and timing of each grouting pipe 7, thereby achieving precise reinforcement of each circumferential area of ​​the concrete sealing body 5.

[0027] Please see Figure 3 The present invention also discloses a construction method for an external sealing secondary structure in pipe jacking construction, used to form the aforementioned external sealing secondary structure in pipe jacking construction, including the following steps: S1. Prepare the tunnel entrance by fixing the tunnel entrance sealing steel plate 1 to the working shaft tunnel entrance 8, installing the water-stop curtain 2 and fixing it with the pressure plate 3. The tunnel entrance sealing steel plate 1 serves as a basic fixing component, providing installation support for the water-stop curtain 2 and the pressure plate 3. After the water-stop curtain 2 is placed between the tunnel entrance sealing steel plate 1 and the jacking pipe section 4, it can form a flexible seal during the jacking process of the jacking pipe section 4. The pressure plate 3 is used to press and fix the water-stop curtain 2 to prevent it from turning outward and to keep the sealing surface flat.

[0028] S2, start the pipe jacking and position the first pipe section. Push the pipe section 4 to the predetermined position outside the working shaft door 8. The pipe jacking machine is installed on the starting bracket. The jacking process is monitored by a dedicated person. Push the first pipe section 4 to a distance of about 1 meter from the working shaft door 8 and stop the machine to ensure accurate positioning of the first pipe section 4. This will facilitate subsequent adjustments of the pressure plate 3, arrangement of the isolation layer 6 and formation of the concrete sealing body 5 between the pipe section 4 and the working shaft door 8.

[0029] S3, adjust the pressure plate 3 so that the pressure plate 3 retracts relative to the sealing steel plate 1 of the tunnel entrance, so as to form a reserved space for secondary sealing construction on the outside of the working well entrance 8. The retraction of the pressure plate 3 can not only retain the primary flexible sealing foundation of the water-stop curtain 2, but also provide operating space for the subsequent arrangement of the isolation layer 6, mold installation, grouting pipe 7 pre-embedding and concrete sealing body 5 pouring.

[0030] S4. Contact surface isolation treatment is carried out. An isolation layer 6 is set in the forming area of ​​the concrete sealing body 5. The isolation layer 6 can be set in the adjacent area between the concrete sealing body 5 and the jacking pipe section 4, the tunnel portal sealing steel plate 1 and the water-stop curtain 2. It is used to form isolation protection during the forming process of the concrete sealing body 5, so as to avoid direct bonding between the concrete sealing body 5 and the jacking pipe section 4, the tunnel portal sealing steel plate 1 or the water-stop curtain 2, and at the same time provide conditions for the subsequent resumption of jacking of the jacking pipe section 4.

[0031] S5, install a mold for forming the concrete sealing body 5, and pre-embed grouting pipe 7 in the forming area of ​​the concrete sealing body 5, so that the grouting pipe 7 extends to the inside of the water-stop curtain 2. The mold is used to limit the forming space of the concrete sealing body 5, so that the concrete sealing body 5 can be arranged around the outer periphery of the jacking pipe section 4 and located outside the water-stop curtain 2. After the grouting pipe 7 is pre-embedded, it can form a grouting channel leading to the inside of the water-stop curtain 2 in the later stage, so as to reinforce and seal the sealing area of ​​the tunnel entrance in case of local leakage.

[0032] S6. Concrete is poured into the mold in layers and vibrated to form a concrete sealing body 5 surrounding the outer periphery of the jacking pipe section 4. Layered pouring and vibration can improve the density and integrity of the concrete sealing body 5, so that it forms a stable rigid sealing structure around the outer periphery of the jacking pipe section 4. Together with the water-stop curtain 2 and the grouting pipe 7, it forms a triple protection system of primary flexible sealing, secondary rigid sealing and subsequent grouting reinforcement.

[0033] S7. The concrete sealing body 5 is cured, and the jacking of the pipe section 4 is resumed after the concrete sealing body 5 reaches the predetermined strength. By resuming the jacking after the concrete sealing body 5 has reached a certain strength, the stability of the external secondary sealing structure during the jacking process can be guaranteed, and the risk of water inrush, sand inrush and leakage at the tunnel portal 8 can be reduced.

[0034] Furthermore, in step S3, the bolts 9 used to connect the pressure plate 3 and the portal sealing steel plate 1 are loosened, causing the pressure plate 3 to retract by 5 cm as a whole. After retraction, the nuts of the bolts 9 are tightened again. The retraction of the pressure plate 3 by 5 cm as a whole can form a relatively stable space reserved for secondary sealing construction on the outside of the working well portal 8, which facilitates subsequent contact surface isolation treatment, mold installation, and concrete sealing body 5 pouring. Tightening the nuts of the bolts 9 after retraction can ensure that the pressure plate 3 remains stable and prevent the pressure plate 3 from loosening or shifting during subsequent construction.

[0035] Furthermore, in step S5, a mold is made according to the outer diameter of the jacking pipe section 4. The inner diameter of the mold is 2-3 cm larger than the outer diameter of the jacking pipe section 4. The grouting pipes 7 are set at least at positions 2, 4, 8 and 10 around the jacking pipe section 4. The inner diameter of the mold is 2-3 cm larger than the outer diameter of the jacking pipe section 4, which can provide reasonable space for the molding of the concrete sealing body 5, so that the concrete sealing body 5 can form a continuous sealing structure around the outer circumference of the jacking pipe section 4. The grouting pipes 7 are set at positions 2, 4, 8 and 10, which is conducive to forming a multi-point grouting reinforcement channel around the jacking pipe section 4, thereby improving the coverage and reliability of the later sealing reinforcement.

[0036] In this embodiment, in step S7, after the concrete sealing body 5 has been poured for 4-5 hours and its initial setting strength has reached 50% of the design value, the jacking of the pipe section 4 is resumed. If leakage occurs later, special sealing material is injected into the inside of the water-stop curtain 2 through the grouting pipe 7 embedded in the concrete sealing body 5 for reinforcement and sealing. The jacking is resumed after the concrete sealing body 5 has reached a certain initial setting strength, which can balance construction efficiency and sealing structure stability, and avoid disturbance or cracking of the concrete sealing body 5 due to premature jacking. The injection of special sealing material through the grouting pipe 7 can reinforce and seal the inside of the water-stop curtain 2 and the sealing area of ​​the tunnel entrance, thereby further improving the sealing reliability of the working well entrance 8.

[0037] This invention, by employing an external sealing secondary structure for pipe jacking construction, effectively reduces downtime losses caused by tunnel portal leakage, lowers the consumption of sealing materials by approximately 30-50%, reduces idle and maintenance costs of construction equipment by approximately 20-30%, and saves on labor costs by approximately 10-30%. Simultaneously, due to smooth construction and reliable sealing, the overall construction period can be shortened by approximately 10-15%, facilitating the project's earlier realization of operational revenue. In summary, applying this solution can save construction units approximately 1 million yuan in comprehensive costs during pipe jacking construction, demonstrating its economic advantages. In practical engineering applications, the external sealing secondary structure for pipe jacking construction of this embodiment has been repeatedly used in the Jakarta Water Supply Project in Indonesia for sealing tunnel portals crossing rivers, with a cumulative jacking length exceeding 10 km. The construction results have been excellent, indicating that this structure and its construction method possess high technical maturity and engineering reliability. This structure is suitable for various complex geological conditions, including water-rich strata, soft soil strata, sandy layers, and high-water-pressure strata. It can be applied to pipe jacking construction projects such as municipal pipelines, power tunnels, water conservancy projects, and transportation tunnels. In specific implementation, the pipe diameter of the jacking section 4 can be in the range of Φ800-Φ3500mm, the construction burial depth can be in the range of 5-50 meters underground, and the groundwater level can be in the range of 0-30 meters above the top of the pipe. This can meet the sealing requirements of tunnel portals under different engineering types and different hydrogeological conditions. The construction process of this embodiment can be carried out while the pipe jacking machine is stopped, without the need for personnel to enter the danger zone. Combined with mechanized pouring, it can reduce the risk of close-range manual operations and improve construction safety. At the same time, the composite sealing system formed by the concrete sealing body 5, the isolation layer 6, and the grouting pipe 7 can effectively prevent water and sand inflow and soil erosion at the tunnel portal 8. The grouting material used can be an environmentally friendly sealing material, thereby reducing the adverse impact on the surrounding environment.

[0038] In summary, this invention discloses an external sealing secondary structure and its construction method for pipe jacking construction. The external sealing secondary structure includes a portal sealing steel plate 1, a water-stop curtain 2, a pressure plate 3, a pipe section 4 passing through the working shaft portal 8, a concrete sealing body 5 surrounding the pipe section 4, an isolation layer 6 located in the area adjacent to the concrete sealing body 5 and the pipe section 4, the portal sealing steel plate 1, and the water-stop curtain 2, and a grouting pipe 7 embedded in the concrete sealing body 5. The construction method, through steps such as portal preparation, pipe jacking initiation and first pipe section positioning, pressure plate 3 retraction, contact surface isolation treatment, mold installation and grouting pipe 7 embedding, layered concrete pouring and vibration, and curing and restoration of the jacking process, enables the external sealing secondary structure to achieve stability based on traditional portal primary sealing. Through the combination of the above structure and construction methods, the pressure plate 3 retracts to form a secondary sealing construction space, the isolation layer 6 forms lubrication, filling and buffer protection, the concrete sealing body 5 forms an external rigid seal, and the grouting pipe 7 reserves a channel for later reinforcement. Thus, a composite sealing system combining flexible sealing, rigid sealing and grouting reinforcement is constructed, which significantly improves the sealing reliability and structural stability of the tunnel portal during pipe jacking construction, effectively reduces the risk of water and sand inrush, soil erosion and construction accidents, while reducing disturbance to surrounding buildings and geological environment, ensuring construction safety, and improving the efficiency of pipe jacking construction and the overall management level of the project. It has good demonstration value and promotion significance for pipe jacking construction fields such as urban underground pipe network construction, water conservancy projects, power tunnels and traffic tunnels.

[0039] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Under the concept of the present invention, the technical features of the above embodiments or different embodiments can also be combined, and there are many other variations of different aspects of the present invention as described above. For the sake of brevity, they are not provided in detail. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A secondary external sealing structure for pipe jacking construction, comprising a portal sealing steel plate (1), a water-stop curtain (2), a pressure plate (3), and a pipe jacking section (4) passing through the portal (8) of the working shaft, characterized in that, It also includes a concrete sealing body (5), an isolation layer (6), and a grouting pipe (7). The portal sealing steel plate (1) is set at the portal (8). The water-stop curtain (2) is set between the portal sealing steel plate (1) and the jacking pipe section (4). The pressure plate (3) is set on the outside of the water-stop curtain (2) and connected to the portal sealing steel plate (1) to fix the water-stop curtain (2). The pressure plate (3) is retractable relative to the portal sealing steel plate (1) to... A reserved space for secondary sealing construction is formed outside the tunnel entrance (8); the concrete sealing body (5) is arranged around the outer periphery of the jacking pipe section (4) and located outside the water-stop curtain (2); the isolation layer (6) is set in the adjacent area of ​​the concrete sealing body (5) and the jacking pipe section (4), the tunnel entrance sealing steel plate (1) and the water-stop curtain (2); the grouting pipe (7) is embedded in the concrete sealing body (5) and extends to the inner side of the water-stop curtain (2).

2. The external sealing secondary structure for pipe jacking construction according to claim 1, characterized in that, The isolation layer (6) includes a grease layer (61) and a geotextile layer (62). The grease layer (61) is applied to the outer surface of the jacking pipe section (4) and the outer surface of the tunnel portal sealing steel plate (1). The geotextile layer (62) is placed on the outer periphery of the jacking pipe section (4) and fills the chamfered area between the jacking pipe section (4) and the water-stop curtain (2).

3. The external sealing secondary structure for pipe jacking construction according to claim 2, characterized in that, The geotextile layer (62) is wrapped around the outer periphery of the jacking pipe section (4) to form 4-5 layers, and the width of the geotextile layer (62) along the axial direction of the jacking pipe section (4) is 30-50 cm.

4. The external sealing secondary structure for pipe jacking construction according to claim 1, characterized in that, The pressure plate (3) is connected to the portal sealing steel plate (1) by bolts (9); the nuts of the bolts (9) are coated with sealant or wrapped with PTFE tape.

5. The external sealing secondary structure for pipe jacking construction according to claim 1, characterized in that, The pressure plate (3) is set in sections along the circumference of the jacking pipe section (4).

6. The external sealing secondary structure for pipe jacking construction according to claim 1, characterized in that, The grouting pipe (7) is pre-embedded in the concrete sealing body (5) at intervals along the circumference of the jacking pipe section (4); the grouting pipe (7) includes at least the grouting pipes (7) set at the 2, 4, 8 and 10 points along the circumference of the jacking pipe section (4), and the grouting pipe (7) is equipped with a control valve (10).

7. A construction method for an external sealing secondary structure in pipe jacking construction, used to form the external sealing secondary structure for pipe jacking construction as described in any one of claims 1-6, characterized in that, Includes the following steps: S1, prepare the tunnel entrance, fix the tunnel entrance sealing steel plate (1) to the working well tunnel entrance (8), install the water-stop curtain (2) and fix the water-stop curtain (2) through the pressure plate (3); S2, start the pipe jacking and position the first pipe section, and push the pipe section (4) to the predetermined position outside the working shaft door (8); S3, adjust the pressure plate (3) so that the pressure plate (3) retracts relative to the sealing steel plate (1) of the tunnel entrance, so as to form a reserved space for secondary sealing construction on the outside of the working well entrance (8); S4, perform contact surface isolation treatment, and set an isolation layer (6) in the forming area of ​​the concrete sealing body (5). S5, install the mold for forming the concrete sealing body (5), and pre-embed the grouting pipe (7) in the forming area of ​​the concrete sealing body (5) so that the grouting pipe (7) extends to the inside of the water-stop curtain (2); S6, pour concrete into the mold in layers and vibrate it to form a concrete sealing body (5) around the outer periphery of the jacking pipe section (4). S7, the concrete sealing body (5) is cured, and the jacking pipe section (4) is resumed after the concrete sealing body (5) reaches the predetermined strength.

8. The construction method of the external sealing secondary structure for pipe jacking construction according to claim 7, characterized in that, In step S3, the bolts (9) used to connect the pressure plate (3) and the door sealing steel plate (1) are loosened, so that the pressure plate (3) is retracted by 5 cm as a whole, and the nuts of the bolts (9) are tightened after the retraction.

9. The construction method of the external sealing secondary structure for pipe jacking construction according to claim 7, characterized in that, In step S5, a mold is made according to the outer diameter of the jacking pipe section (4). The inner diameter of the mold is 2-3 cm larger than the outer diameter of the jacking pipe section (4). The grouting pipe (7) is set at least at the 2nd, 4th, 8th and 10th points around the jacking pipe section (4).

10. The construction method of the external sealing secondary structure for pipe jacking construction according to claim 7, characterized in that, In step S7, after the concrete sealing body (5) is poured for 4-5 hours and the initial setting strength reaches 50% of the design value, the jacking pipe section (4) is resumed. If leakage occurs later, special sealing material is injected into the inside of the water-stop curtain (2) through the grouting pipe (7) embedded in the concrete sealing body (5) to reinforce and seal it.

Images