A construction method for large-section double-jacking pipe and working well

Abstract

This invention relates to a construction method for large-section double-jacking pipes and working shafts, comprising the following steps: constructing the support system for the launching shaft; after the launching shaft is completed, dismantling part of the support system, leaving the other part inside the launching shaft; constructing the main structure of the launching shaft, simultaneously transferring a portion of the dismantled support system along with the remaining support system to the main structure; performing double-jacking pipe construction; and simultaneously constructing the receiving shaft, transferring another portion of the dismantled support system to the receiving shaft's support system. This construction method significantly reduces the overlapping construction steps between the working shaft foundation pit support and the main structure, significantly shortens the structural construction cycle, and reduces the steps of support installation and dismantling, concrete removal, and transportation, effectively reducing project costs and construction safety risks, and achieving rapid, safe, and green construction of the working shaft structure.

Description

Technical Field

[0001] This invention belongs to the field of pipe jacking technology, and relates to the working shaft of pipe jacking, especially a construction method for a large-section double pipe jacking and working shaft. Background Technology

[0002] With urbanization and the development of underground space, the demand for large-scale underground tunnels is becoming increasingly urgent. To accommodate various pipelines such as water supply, drainage, electricity, communications, and gas, their cross-sectional dimensions can reach 5 to 6 meters or more. In the engineering practice of double-pipe jacking construction, the launching shaft, as the base for the installation, launch, and initial advancement of the pipe jacking equipment, directly affects subsequent processes through its structural design and construction plan. Existing construction methods still have the following shortcomings:

[0003] 1. In the traditional starting well construction, the support system is dismantled and abandoned before the main structure is constructed. This "build-dismantle-abandon" model not only causes a large amount of steel, concrete and other materials to be directly wasted, but also requires additional manpower and machinery for dismantling and removal. Especially under the conditions of large cross section and deep foundation pit, the amount of steel or concrete used in the support structure is huge, which significantly increases the construction cost.

[0004] 2. In the existing process, pipe jacking can only be carried out after the starting well and receiving well have been completed. This operation mode results in a long total construction period. Especially for double pipe jacking projects, there is redundancy in the construction period.

[0005] 3. Before constructing the main structure of the starting shaft, the various support structures in the foundation pit will be dismantled. This poses a high safety risk for deep foundation pits of a large size. Furthermore, in order to ensure that the pipe jacking machine and pipe sections are successfully lowered into the foundation pit, the top plate of the secondary lining structure cannot be sealed, further exacerbating the safety hazards of the foundation pit. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a construction method for large-section double pipe jacking and working wells that has a short construction period and high construction quality.

[0007] To solve the above problems, the technical solution of the present invention is as follows:

[0008] A method for constructing a large-section double-jacking pipe working well includes the following steps:

[0009] Support system for the starting well;

[0010] After the launching well is completed, part of the support system is removed, while the other part of the support system remains inside the launching well.

[0011] The main structure of the starting shaft was constructed, and a portion of the dismantled support system, along with the support system remaining in the starting shaft, was transferred to the main structure.

[0012] Double pipe jacking construction was carried out;

[0013] The construction of the receiving well is carried out simultaneously with the construction of the double pipe jacking system, and another part of the dismantled support system is transferred to the support system of the receiving well.

[0014] In a further embodiment, the support system includes several concrete supports, several steel supports, several waist beams and ring frame beams, with the waist beams and ring frame beams longitudinally spaced on the diaphragm wall of the starting shaft, and the ring frame beams located in the middle of the waist beams.

[0015] Several concrete supports and several steel supports are respectively fixedly installed on several waist beams and ring frame beams.

[0016] In a further embodiment, after the launching well is completed, part of the support system is removed, while the other part of the support system remains in the launching well, specifically including:

[0017] Several concrete supports, several steel supports, and part of the lintel were removed;

[0018] Leave the ring frame beam and one waist beam inside the launching shaft, with the retained waist beam corresponding to the backrest position of the launching shaft.

[0019] In a further embodiment, the main structure of the launching shaft is constructed, and a portion of the dismantled support system, along with the support system remaining in the launching shaft, is reused in the main structure, specifically including:

[0020] The removed concrete supports were used as the central column of the launching well.

[0021] In a further embodiment, the main structure of the launching shaft, which also includes a portion of the dismantled support system and the support system remaining in the launching shaft, is reused in the main structure, further comprising:

[0022] Connect the ring frame beam to the side walls of the main structure;

[0023] The bottom end of the ring frame beam is provided with a boss. Waterstop strips and second grouting pipes are fixed in the middle of the upper and lower sides of the ring frame beam. The outlet end of the second grouting pipe is located on the surface of the ring frame beam.

[0024] A waterstop is fixedly installed at the top center of the ring beam, and a waterstop is fixedly installed on the side end face of the boss.

[0025] In a further embodiment, the locations of several construction joints of the diaphragm wall correspond to the inner end face of the backrest.

[0026] A waterstop plate is fixedly installed around the opening of the diaphragm wall jacking pipe, and the waterstop plate is located at the junction of the diaphragm wall and the side wall.

[0027] Several third grouting pipes are fixedly installed at intervals inside the side wall, and the outlet ends of the third grouting pipes are located on the inner surface of the waterstop plate.

[0028] A construction method for large-section double-jacking pipes, wherein the launching well of the double-jacking pipe is constructed using the working well construction method for large-section double-jacking pipes, includes the following steps:

[0029] When the pipe jacking is carried out first, the corresponding top plate is moved to the corresponding backrest position and used as a back plate. The top plate on the side of the pipe jacking is located at the top of the starting shaft.

[0030] After the initial pipe jacking is completed, the corresponding top plate is moved from the backrest position to the top of the starting shaft and fixed.

[0031] The top plate on the rear jacking side is moved from the top of the starting well to the corresponding backrest position and used as a back plate.

[0032] Then proceed with the subsequent pipe jacking construction;

[0033] After the subsequent pipe jacking construction is completed, the corresponding top plate is moved from the backrest position to the top of the starting shaft and fixed.

[0034] In a further embodiment, during the initial pipe jacking, the corresponding top plate is moved to the corresponding backrest position to serve as a back plate, and the top plate on the subsequent pipe jacking side is located at the top of the starting shaft, specifically including:

[0035] The top slab consists of several sections;

[0036] When the top panel is used as the back panel, the connection method of several blocks is adjusted so that the overall shape of the blocks corresponds to the backrest.

[0037] In a further embodiment, a plurality of pre-embedded steel plates are fixedly mounted around the outer surface of the sidewall at intervals;

[0038] When the top plate is used as a back panel, several embedded steel plates are fixed with clamps, and several clamps are clamped to the side walls to attach the backrest and the top plate.

[0039] In a further embodiment, after the initial pipe jacking is completed, the corresponding top plate is moved from the rear backrest position to the top of the launching shaft and fixed, specifically including:

[0040] The top plate is fixedly installed on the ring frame beam or waist beam located at the top of the launching shaft;

[0041] The first grouting pipe is fixedly installed inside the ring beam or waist beam, and the outlet end of the first grouting pipe is located at the junction of the top plate and the ring beam or waist beam.

[0042] One end of the pre-embedded steel bar is fixed on the ring beam or the waist beam, and the other end of the pre-embedded steel bar is located inside the top slab.

[0043] Compared with the prior art, the beneficial effects of the present invention are:

[0044] 1. This construction method deeply optimizes the working well support system in conjunction with the main structure, pre-constructs the ring beam at the slab location of the main structure, and replaces the concrete lintel beam of the third concrete support with the ring beam. It also incorporates a series of innovative measures, such as converting the concrete support into a central column, converting the top slab into a back slab, and implementing waterproofing. This method significantly reduces the overlapping construction steps between the working well foundation pit support and the main structure, substantially shortens the structural construction cycle, and reduces the need for support installation and dismantling, concrete removal, and transportation. This effectively lowers project costs and construction safety risks, achieving rapid, safe, and green construction of the working well structure.

[0045] 2. This construction method, by simultaneously constructing the main structure ring frame beam during the foundation pit support stage, achieves several advantages: First, it completely eliminates the need for separate subsequent construction of the ring frame beam, shortening the overall construction period of the main structure of the working well. Second, as part of the main structure, the ring frame beam has a higher concrete design grade and reinforcement than traditional temporary concrete lintel beams, significantly improving the long-term safety and stability of the foundation pit during construction. Third, it directly avoids the later dismantling of the concrete lintel beam and corresponding supports, eliminating construction safety risks such as falls and impacts during dismantling. Fourth, at the backrest position of the open section, the lintel beam can also serve as a tie beam for the backrest, effectively restraining the displacement and deformation of the backrest wall during the large-section pipe jacking process, ensuring the overall stability of the backrest structure.

[0046] 3. This construction method implements a five-layer waterproof structure in the ring beam area: First, a second grouting pipe is pre-embedded above and below the ring beam for grouting and water sealing of construction joints later; second, water-swellable waterstop strips are installed in the middle of the upper and lower parts of the ring beam to achieve self-expanding sealing upon contact with water; third, steel plate waterstops are pre-embedded above and below the ring beam during its construction to form a rigid water-stop barrier; fourth, a protrusion is designed at the bottom of the ring beam to increase the anti-seepage distance by extending the groundwater seepage path; fifth, cement waterproof coating is applied to the upper and lower surfaces of the ring beam to form a multi-layered composite waterproof system that effectively blocks leakage channels.

[0047] 4. This construction method involves constructing the launching shaft first, followed by the receiving shaft after the pipe jacking begins. This avoids the need to invest a large amount of labor in both shafts simultaneously, achieving a balanced utilization of human resources. In addition, the construction of the receiving shaft is carried out simultaneously during the pipe jacking process, ensuring that the construction period of the receiving shaft fully covers the pipe jacking operation cycle without occupying additional critical construction time, thus significantly improving overall construction efficiency.

[0048] 5. This construction method replaces the cast-in-place central column of the launching shaft's main structure with a precast component, and innovatively uses the central column as a concrete support for the support system during construction. The concrete supports within the launching shaft are removed, with some retained and reused in the main structure. This method achieves three benefits: firstly, it significantly reduces the time spent on on-site rebar tying, formwork erection, and concrete curing, shortening the construction period of the launching shaft; secondly, it avoids the large amount of waste concrete removal and transportation required after the removal of traditional concrete supports, thus saving energy and protecting the environment; and thirdly, as a central column, its load-bearing capacity far exceeds the design value of the concrete supports, providing a higher safety redundancy during the support's service life.

[0049] 6. This construction method improves the structure of the diaphragm wall in the following ways: First, the diaphragm wall at the back of the open section is modularly designed so that the joints of the diaphragm wall effectively avoid the concentrated stress area of ​​the back jack; second, waterstops are installed around the openings of the side walls and diaphragm walls to physically block the path of water leakage from the diaphragm wall into the starting well; third, a third grouting pipe is pre-installed inside the side wall to fill the void behind the waterstop and can be injected with flexible waterstop materials such as polyurethane. Together with the rigid blocking of the waterstop, it forms a composite waterstop system that combines rigidity and flexibility. The third grouting pipe can still be reused after the main structure of the open section is completed.

[0050] 7. In this construction method, during double-pipe jacking, the top plate of the first jacking pipe side is hoisted to the front of the rear backrest and used as a back plate. The top plate of the second jacking pipe side is set on the corresponding ring frame beam. After the first jacking pipe is completed, the back plate is hoisted back onto the corresponding ring frame beam and continues to serve as the top plate. The top plate of the second jacking pipe side is then reused as the back plate. This method of reusing the top plate has two advantages: First, the top plate serves as a rear reaction support during pipe jacking, eliminating the need for additional backrest installation or reinforcement, thus saving materials and time. Second, during single-sided jacking, a top plate is installed at the top of the non-jacking side, effectively stabilizing the working shaft structure and significantly reducing the risk of pit instability caused by unloading during single-sided jacking. This method unifies the construction methods for the back plate and top plate, eliminating the need for additional construction costs and specialized equipment, making construction convenient and efficient. Attached Figure Description

[0051] Figure 1 A flowchart of a construction method for a large-section double-jacking working well;

[0052] Figure 2 A flowchart of a construction method for large-section double-jacking pipes;

[0053] Figure 3 A side view of the support system for a large-section double-jacking working well construction method;

[0054] Figure 4 A top view of the support system for a large-section double-jacking working well construction method;

[0055] Figure 5 A schematic diagram of the backrest for a construction method of a large-section double-jacking working well;

[0056] Figure 6 This is a schematic diagram of step S201 of a construction method for a large-section double-jacking pipe;

[0057] Figure 7 A schematic diagram of the top slab conversion for a large-section double-jacking pipe construction method;

[0058] Figure 8 This is a schematic diagram of the temporary installation of the top slab and ring frame beam in a construction method for large-section double-jacking pipes.

[0059] Figure 9 This is a front view of the connection between the top slab and the backrest in a construction method for large-section double-jacking pipes.

[0060] Figure 10 A top view showing the connection between the top slab and the backrest in a construction method for large-section double-jacking pipes;

[0061] Figure 11 This is a schematic diagram of the fixed installation of the top slab and the ring frame beam in a construction method for large-section double-jacking pipes.

[0062] Figure 12 A schematic diagram of the installation of the ring frame beam and sidewalls for a construction method of a large-section double-jacking pipe working well;

[0063] Figure 13 A front view of the diaphragm wall for a construction method of a large-section double-jacking working well;

[0064] Figure 14 This is a diaphragm wall side view of a construction method for a large-section double-jacking working well.

[0065] In the diagram: 1. Launching well; 2. Support system; 201. Concrete support; 202. Steel support; 203. Ring frame beam; 2031. Groove; 2032. First grouting pipe; 2033. Embedded steel bar; 2034. Second grouting pipe; 2035. Waterstop strip; 2036. Waterstop belt; 2037. Boss; 204. Waist beam; 3. Diaphragm wall; 4. Backrest; 5. Top plate; 501. Filler; 6. Hydraulic cylinder frame; 7. Clamping plate; 8. Side wall; 801. Third grouting pipe; 802. Waterstop plate; 803. Embedded steel plate. Detailed Implementation

[0066] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0067] Example 1:

[0068] A construction method for large-section double-jacking pipes and working shafts, such as Figures 1 to 14 As shown, it includes the following steps:

[0069] Step S101, Support system 2 for construction starting well 1:

[0070] According to construction requirements, a number of precast concrete supports 201 are prepared. Preferably, the number of concrete supports 201 is greater than the number required for the support system 2 of the starting shaft 1, and is reserved for backup.

[0071] like Figures 1 to 4 As shown, during the construction of the starting shaft 1, a support system 2 is constructed within the diaphragm walls 3 surrounding the starting shaft 1. Traditional deep foundation pit support often employs steel support construction techniques, which are cumbersome to install and dismantle, and less stable than concrete supports. To facilitate the construction of the foundation pit and main structure, reduce support safety risks, and accelerate project progress, the support system of this application is improved: the support system 2 includes several precast concrete supports 201, several steel supports 202, ring frame beams 203, and several waist beams 204. Several waist beams 204 and ring frame beams 203 are sequentially and intermittently fixed to the inner wall of the diaphragm wall 3 from top to bottom. Both the waist beams 204 and ring frame beams 203 are horizontally arranged, with the ring frame beams 203 located in the middle of the waist beams 204. Specifically, there are four waist beams 204, and two ring frame beams are installed on the upper and lower sides of the ring frame beams 203 respectively. Several concrete supports 201 and several steel supports 202 are fixedly installed on several waist beams 204 and ring beams 203 respectively. Specifically, there are three concrete supports 201 and two steel supports 202. The first, third and fourth supports from top to bottom are all concrete supports 201, and the second and fifth supports are all steel supports 202. That is, concrete supports 201 are fixedly installed on the ring beams 203.

[0072] Due to the immense pressure exerted during the jacking of large-section pipe jacking, the diaphragm wall 3 experiences slight deformation, making it prone to leaks along its joints. For example... Figure 13 As shown, the construction joint of the diaphragm wall 3 is set at the side end face of the backrest 4, so that the construction joint of the diaphragm wall 3 avoids the weak stress position of the jack of the backrest 4, avoids leakage points in the diaphragm wall 3, and improves the construction quality of the diaphragm wall 3.

[0073] Step S103: After the launching shaft 1 is completed, part of the support system 2 is removed, while the other part of the support system 2 remains in the launching shaft 1.

[0074] After the launching shaft 1 is completed, several concrete supports 201, several steel supports 202, and part of the waist beams 204 are removed, with some concrete supports 201 retained for later use. The ring frame beam 203 and one waist beam 204 are retained within the launching shaft 1 for later use as part of the main structure of the launching shaft 1, saving construction costs and shortening the construction period. Specifically, the retained waist beam 204 will be used as the tie beam for the backrest 4; therefore, the retained waist beam 204 needs to be determined according to the position of the backrest 4. In this embodiment, the retained waist beam 204 is the fourth from top to bottom; if the ring frame beam 203 is not considered, it is the third waist beam 204. If the backrest 4 has other dimensions, other corresponding waist beams 204 can be retained according to construction requirements.

[0075] Step S105: Construct the main structure of the launching shaft 1, and simultaneously transfer a portion of the dismantled support system 2, along with the support system 2 remaining in the launching shaft 1, to the main structure:

[0076] Construction will be carried out on the main structure of the launching shaft 1 and the rear backrest 4, including:

[0077] Since the number of central columns in the main structure is less than the number of supports, some of the dismantled concrete supports 201 will be used as central columns in the main structure of the launching well 1; if the number is insufficient, the remaining prefabricated concrete supports 201 that are not used as the support system 2 can be used.

[0078] like Figure 5 As shown, the backrest 4 is constructed on the front side of the retained wainscoting 204. The top of the backrest 4 is higher than the wainscoting 204, so that the retained wainscoting 204 is used as a tie beam for the backrest 4, thereby improving the structural strength of the backrest 4. Specifically, two backrests 4 are provided, corresponding to the positions of the double jacking pipes respectively; the two backrests 4 are located on both sides of the wainscoting 204, and the inner and outer ends of the two backrests 4 are connected to the wainscoting 204, so that the two backrests 4 form an integral load-bearing structure through the wainscoting 204.

[0079] like Figure 12As shown, when constructing the side wall 8 of the starting shaft 1, the retained ring frame beam 203 is connected to the side wall 8 to serve as the ring frame beam 203 of the main structure's middle slab. Depending on construction requirements, other ring frame beams 203 can also be constructed on the side wall 8. The bottom surface of the end where the ring frame beam 203 connects to the side wall 8 has a downwardly protruding boss 2037. A pair of waterstop strips 2035 and a pair of waterstop belts 2036 are pre-embedded between the ring beam 203 and the side wall 8. The pair of waterstop strips 2035 are located at the middle of the top and bottom surfaces of the ring beam 203, respectively. The pair of waterstop belts 2036 are located at the middle of the top surface of the ring beam 203 and the middle of the side surface of the boss 2037, respectively. The waterstop belts 2036 are perpendicular to the surface of the ring beam 203. Half of the waterstop belts 2036 are embedded in the ring beam 203, and the other half of the waterstop belts 2036 are embedded in the side wall 8. The lower waterstop belt 2036 is located on the side of the boss 2037 near the interior of the starting well 1. Specifically, the waterstop strip 2035 and waterstop belt 2036 are set perpendicular to the extension direction of the ring beam 203, that is, the waterstop strip 2035 and waterstop belt 2036 are set along the width of the ring beam 203, and the length of the waterstop strip 2035 and waterstop belt 2036 corresponds to the width of the ring beam 203. Several second grouting pipes 2034 are set at intervals in the sidewalls 8 on the upper and lower sides of the ring beam 203. The inlet end of the second grouting pipe 2034 extends into the starting well 1, which is suitable for grouting; the outlet end of the second grouting pipe 2034 is located on the surface of the ring beam 203. The seepage path can be extended by the boss 2037, waterstop strip 2035, and waterstop belt 2036, and then the construction joint between the ring beam 203 and the sidewall 8 is sealed by grouting through the second grouting pipes 2034, so as to ensure the construction quality of the sidewall 8 and the ring beam 203. Preferably, adjacent second grouting pipes 2034 are spaced 5 meters apart, and a cement-based penetrating crystalline waterproof coating is applied to the surface of the ring beam 203 that contacts the side wall 8.

[0080] like Figure 14 As shown, a waterstop plate 802 is installed at the opening of the diaphragm wall 3. The waterstop plate 802 is installed around the opening of the diaphragm wall 3 to block the path of seepage water from the diaphragm wall 3 into the starting well 1. Specifically, the waterstop plate 802 has a T-shaped structure; the waterstop plate 802 includes two L-shaped angle steels arranged opposite each other, with the two angle steels located at the opening positions of the side wall 8 and the diaphragm wall 3, respectively. Several third grouting pipes 801 are embedded at intervals inside the side wall 8. The inlet end of the third grouting pipe 801 extends to the outside of the side wall 8, and the outlet end of the third grouting pipe 801 is located inside the angle steel, suitable for filling the void behind the angle steel; and the third grouting pipes 801 can continue to be used after the main structure of the open section is completed in the later stage. Waterstop materials such as polyurethane are injected through the third grouting pipes 801 to form a rigid-flexible waterstop system.

[0081] Step S107: Perform double pipe jacking construction:

[0082] In traditional construction techniques, the backing for the pipe jacking is installed after the secondary lining structure sidewalls are constructed. This application improves upon this by implementing double pipe jacking after the main structure of the launching shaft 1 is completed. The double pipes are spaced apart within the launching shaft 1 and constructed sequentially. Figure 2 As shown, the double-jacking pipe construction specifically includes the following steps:

[0083] Step S201: During the initial pipe jacking construction, the corresponding top plate 5 is moved to the corresponding backrest 4 position to serve as a back plate. The top plate 5 on the subsequent pipe jacking side is located at the top of the starting shaft 1.

[0084] like Figure 6 , Figure 8 As shown, in traditional processes, after jacking, the middle and top slabs are constructed using formwork and reinforced concrete, employing a cast-in-place method. This process is time-consuming. To ensure rapid closure of the working shaft after jacking and to guarantee the overall stability of the working shaft during the jacking process, several top slabs 5 are prefabricated. After the main structure of the starting shaft 1 is completed, these top slabs 5 are hoisted into the starting shaft 1. For one side of the subsequent jacking, the corresponding top slab 5 is placed on the corresponding ring frame beam 203 within the starting shaft 1. The top of the ring frame beam 203 has a groove 2031, which surrounds the ring frame beam 203 and is located at a position corresponding to the top slab 5. This allows part or all of the side face of the top slab 5 to be placed within the groove 2031, enabling rapid installation of the top slab 5.

[0085] like Figure 6 , Figure 7 As shown, the top plate 5 comprises several unit plates, and in this embodiment, there are three unit plates. When the top plate 5 is placed on the ring beam 203, the unit plates are temporarily connected. Specifically, each of the unit plates has a pre-embedded reinforcing bar 2033 at its side end, and a double-threaded sleeve is installed on the pre-embedded reinforcing bar 2033. When connecting the unit plates, grooves are cut into the pre-embedded reinforcing bars 2033 and the corresponding positions of adjacent unit plates, a portion of the pre-embedded reinforcing bars 2033 is chiseled out, and the chiseled portion of the pre-embedded reinforcing bars 2033 is inserted into the adjacent unit plate. The double-threaded sleeve is then tightened to complete the temporary connection between the unit plates. For the specific structure, please refer to [reference needed]. Figure 11 Four lifting rings are spaced apart on the unit plate for lifting and hoisting. The arrangement of the lifting rings must take into account the cylinder frame 6 of the pipe jacking machine and avoid the position of the cylinder frame 6 to avoid affecting the subsequent installation of the cylinder. The lifting rings can also be arranged as embedded type. After the hoisting is completed, they are cut off and backfilled with high-strength concrete.

[0086] like Figure 7As shown, for one side of the pipe jacking, several unit plates of the top plate 5 are separated and hoisted to the front of the backrest 4. These unit plates are then reassembled into a shape corresponding to the backrest 4 to form a back panel. The back panel is temporarily fixed to the side wall 8, with the backrest 4 sandwiched between the back panel and the side wall 8. A hydraulic cylinder frame 6 is then installed in front of the back panel, suitable for pipe jacking construction. Alternatively, several unit plates can be pre-assembled into a shape corresponding to the backrest 4 to form a back panel, which is then hoisted to the front of the backrest 4 and fixed to the side wall 8. In this embodiment, one unit plate is placed horizontally, and two other unit plates are placed vertically at both ends of the horizontal unit plate, forming a U-shaped structure corresponding to the backrest 4.

[0087] like Figure 9 , Figure 10 As shown, several embedded steel plates 803 are spaced apart on the side walls 8 surrounding the backrest 4. Several clamping plates 7 are fixedly installed on the embedded steel plates 803. The clamping plates 7 have a Z-shaped cross-section, meaning the main body of the clamping plate 7 is a longitudinal plate, with horizontal plates at both ends. Two horizontal plates are located on either side of the longitudinal plate and are perpendicular to it. One horizontal plate of the clamping plate 7 is welded and fixed to the embedded steel plate 803, while the other horizontal plate is clamped to the front end of the backrest. Thus, the backrest and the backrest 4 are sequentially clamped onto the inner side of the clamping plates 7 from the outside in. Furthermore, due to construction errors in the main structure (construction accuracy, surface flatness, etc.), deviations in the wall's verticality and gaps between the wall and the backrest are inevitable. Considering that the backrest can be removed intact from the side walls 8 after the jacking is completed, it is also possible to use it as the top plate 5. The core idea is to prevent the filling material from forming a permanent bond with the back panel of the side wall 8. Before installation, the verticality and flatness of the side wall 8 and / or the backrest 4 are checked. If the gap is small, a high-strength cement mortar leveling layer is used. If the gap is large, the filler 501 is used first. The filler 501 is a steel plate + rubber pad. Preferably, the pre-embedded steel plate 803 can also be replaced by a later "chemical anchor". The filler 501 can be installed between the back panel and the backrest 4, and between the backrest 4 and the side wall 8.

[0088] Step S203: After the preliminary pipe jacking construction is completed, the corresponding top plate 5 is moved from the rear backrest 4 position to the top of the starting shaft 1 and fixed:

[0089] After the jacking of the pilot pipe is completed, the top plate 5 on the side of the pilot pipe is hoisted out from the rear backrest 4 position, and the unit plates of the top plate 5 are reassembled to form a complete top plate 5. The top plate 5 is then placed on the corresponding ring frame beam 203 and fixed to the ring frame beam 203. Alternatively, the unit plates of the top plate 5 can be hoisted onto the corresponding ring frame beam 203, and then several unit plates can be fixedly connected together. When fixing several unit plates together, they are connected by pre-embedded steel bars 2033, and the joints between adjacent unit plates are filled with high-strength concrete to ensure that the several unit plates are firmly connected together.

[0090] like Figure 11 As shown, pre-embedded reinforcing bars 2033 are embedded at the side ends of the ring beam 203 and the side ends of the top plate 5, and double-threaded sleeves are installed on the pre-embedded reinforcing bars 2033. When fixing the top plate 5, the positions of the pre-embedded reinforcing bars 2033 in the ring beam 203 and / or the top plate 5 are grooved, a portion of the pre-embedded reinforcing bars 2033 is chiseled out, the chiseled portion of the pre-embedded reinforcing bars 2033 is inserted into the ring beam 203 and / or the top plate 5, and the double-threaded sleeves are tightened to fix the top plate 5 on the ring beam 203. A plurality of first grouting pipes 2032 are embedded at intervals within the ring beam 203 or the top slab 5. The inlet ends of the first grouting pipes 2032 are all connected to the outside of the ring beam 203 or the top slab 5, suitable for grouting. The outlet ends of the first grouting pipes 2032 are located at the contact surface between the ring beam 203 and the top slab 5. Grouting is performed on the joints and grooves between the ring beam 203 and the top slab 5 through the first grouting pipes 2032 to ensure construction quality. Preferably, the interval between adjacent first grouting pipes 2032 is 0.5-1m. The first grouting pipes 2032 are reusable grouting pipes, which can still be used for grouting and leak repair during later operation and maintenance. First grouting pipes 2032 can also be installed in the unit slabs of the top slab 5, and cement grout is injected through the joints of the first grouting pipes 2032.

[0091] Step S205: Move the top plate 5 on the rear jacking side from the top of the starting shaft 1 to the corresponding rear backrest 4 position to serve as a backrest:

[0092] As in step S201, the top plate 5 on the rear jacking side is hoisted from the ring frame beam 203 of the starting shaft 1 to the front side of the backrest 4. Several unit plates of the top plate 5 are assembled into a shape corresponding to the backrest 4 to form a back plate. The back plate is then temporarily fixed to the side wall 8 by several clamps 7.

[0093] Step S207: Perform subsequent pipe jacking construction:

[0094] After the back plate on the side of the jacking pipe is temporarily fixed, the construction of the jacking pipe will proceed.

[0095] Step S209: After the subsequent pipe jacking construction is completed, move the corresponding top plate 5 from the rear backrest 4 position to the top of the starting shaft 1 and fix it:

[0096] As in step S203, after the construction of the rear jacking pipe is completed, the back plate on the side of the rear jacking pipe is hoisted from the backrest 4 position to the corresponding ring frame beam 203, several unit plates are reassembled to form the top plate 5, and finally the top plate 5 is fixedly installed on the corresponding ring frame beam 203 to complete the double jacking pipe construction.

[0097] Step S109: Simultaneously with the double-jacking construction, the receiving well is constructed, and another part of the dismantled support system 2 is transferred to the support system of the receiving well.

[0098] After the support system 2 of the launching shaft 1 is dismantled, construction of the receiving shaft begins. Furthermore, the construction of the receiving shaft can be carried out simultaneously with the main structure construction of the launching shaft 1 or double pipe jacking, thereby improving construction efficiency and shortening the construction period.

[0099] After the support system 2 of the launching shaft 1 is dismantled, a portion of the dismantled concrete supports 201 are reused as the main structure of the launching shaft 1, while the remaining portion is reused in the support system of the receiving shaft. If the remaining concrete supports 201 are insufficient, pre-fabricated and reserved concrete supports 201 can be used for joint support. After the receiving shaft is completed, the concrete supports 201 are dismantled, and some of them can be reused as central columns in the main structure of the receiving shaft. Furthermore, the support system of the receiving shaft can adopt the same or similar structure as the support system 2 of the launching shaft 1, that is, the ring frame beam 203 is constructed simultaneously with the support system 2, and the ring frame beam 203 is used as part of the support system 2. Subsequently, the ring frame beam 203 can be retained as part of the main structure of the receiving shaft, saving construction costs and shortening the construction period.

[0100] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for constructing a working shaft of a large-section double jacking pipe, characterized in that, Includes the following steps: Support system (2) for the starting well (1); After the starting well (1) is completed, part of the support system (2) is removed, and the other part of the support system (2) remains in the starting well (1); The main structure of the starting well (1) is constructed, and a portion of the dismantled support system (2) and the support system (2) remaining in the starting well (1) are transferred to the main structure. Double pipe jacking construction was carried out; While the double-jacking pipe construction is being carried out, the construction of the receiving well is also carried out, and another part of the dismantled support system (2) is transferred to the support system of the receiving well.

2. The method of construction of a work shaft for a large cross-section double pipe jacking according to claim 1, characterized in that, The support system (2) includes several concrete supports (201), several steel supports (202), several waist beams (204) and ring frame beams (203). Several waist beams (204) and ring frame beams (203) are longitudinally spaced on the diaphragm wall (3) of the starting well (1). The ring frame beams (203) are located in the middle of several waist beams (204). A number of concrete supports (201) and a number of steel supports (202) are respectively fixedly installed on a number of waist beams (204) and ring frame beams (203).

3. The method according to claim 2, wherein After the launching well (1) is completed, part of the support system (2) is removed, while another part of the support system (2) remains in the launching well (1), specifically including: Remove some of the concrete supports (201), some of the steel supports (202), and part of the lintel (204). The ring frame beam (203) and the waist beam (204) are left in the launching well (1), with the retained waist beam (204) corresponding to the backrest (4) position of the launching well (1).

4. The method according to claim 3, wherein The main structure of the launching well (1) is constructed, and a portion of the dismantled support system (2) and the support system (2) remaining in the launching well (1) are reused in the main structure, specifically including: The removed portion of the concrete support (201) is used as the central column of the launching well (1).

5. The method according to claim 4, wherein The construction of the main structure of the launching well (1) includes the transfer of a portion of the dismantled support system (2) and the support system (2) remaining in the launching well (1) to the main structure, and also includes: The ring frame beam (203) is connected to the side wall (8) of the main structure; The bottom end of the ring frame beam (203) is provided with a boss (2037). Waterstop strips (2035) and second grouting pipes (2034) are fixedly installed in the middle of the upper and lower sides of the ring frame beam (203). The outlet end of the second grouting pipe (2034) is located on the surface of the ring frame beam (203). A waterstop (2036) is fixedly installed at the middle of the top part of the ring beam (203), and the waterstop (2036) is fixedly installed on the side end face of the boss (2037).

6. The construction method for a large-section double-jacking pipe working well according to claim 5, characterized in that, The positions of several construction joints of the diaphragm wall (3) correspond to the inner end face of the backrest (4); The jacking pipe opening of the diaphragm wall (3) is surrounded by a fixed waterstop plate (802), which is located at the junction of the diaphragm wall (3) and the side wall (8). Several third grouting pipes (801) are fixedly installed at intervals inside the side wall (8), and the outlet ends of several third grouting pipes (801) are located on the inner surface of the waterstop plate (802).

7. A construction method for a large-section double-jacking pipe, wherein the starting well (1) of the double-jacking pipe is constructed using the working well construction method for a large-section double-jacking pipe as described in claim 5 or 6, characterized in that, Includes the following steps: When the pipe jacking is carried out first, the corresponding top plate (5) is moved to the corresponding backrest (4) position and used as a back plate. The top plate (5) on the side of the pipe jacking is located at the top of the starting well (1). After the initial pipe jacking construction is completed, the corresponding top plate (5) is moved from the backrest (4) position to the top of the starting well (1) and fixed. The top plate (5) on the rear jacking side is moved from the top of the starting well (1) to the corresponding rear backrest (4) position and used as a back plate; Then proceed with the subsequent pipe jacking construction; After the subsequent pipe jacking construction is completed, the corresponding top plate (5) is moved from the backrest (4) position to the top of the starting well (1) and fixed.

8. The construction method for large-section double-jacking pipes according to claim 7, characterized in that, During the initial pipe jacking construction, the corresponding top plate (5) is moved to the corresponding backrest (4) position to serve as a back plate. The top plate (5) on the subsequent pipe jacking side is located at the top of the starting shaft (1), specifically including: The top plate (5) comprises several pieces; When the top plate (5) is used as a back panel, the connection method of the several blocks is adjusted so that the overall shape of the several blocks corresponds to the backrest (4).

9. The construction method for large-section double-jacking pipes according to claim 8, characterized in that, Several pre-embedded steel plates (803) are fixedly installed around the outer surface of the side wall (8) at intervals. When the top plate (5) is used as a back plate, a number of the pre-embedded steel plates (803) are fixedly fitted with a clamping plate (7), and the backrest (4) and the top plate (5) are clamped between the clamping plate (7) and the side wall (8).

10. The construction method of large-section double-jacking pipe according to claim 9, characterized in that, After the initial pipe jacking is completed, the corresponding top plate (5) is moved from the backrest (4) to the top of the launching shaft (1) and fixed, specifically including: The top plate (5) is fixedly installed on the ring frame beam (203) or waist beam (204) located at the top of the starting well (1); The first grouting pipe (2032) is fixedly installed inside the ring beam (203) or waist beam (204), and the outlet end of the first grouting pipe (2032) is located at the junction of the top plate (5) and the ring beam (203) or waist beam (204). One end of the pre-embedded steel bar (2033) is fixed on the ring beam (203) or the waist beam (204), and the other end of the pre-embedded steel bar (2033) is located in the top plate (5).

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