Top shield launch structure and method of construction

Abstract

The application discloses a top shield starting structure and a construction method thereof, and the top shield starting structure comprises a working well foundation pit, an inner support system and a counterforce seat system; the counterforce seat system is arranged on the back of the working well foundation pit along the tunneling direction of a top shield machine, and the counterforce seat system comprises a top shield counterforce seat platform and a prestressed reinforcing structure; the prestressed reinforcing structure comprises fastening blocks and prestressed steel strands; the first end of the prestressed steel strands is fixed on the top shield counterforce seat platform through the fastening blocks, the second end of the prestressed steel strands is fixed on the bottom plate of the working well foundation pit through the fastening blocks, and the prestressed steel strands are used for connecting the counterforce seat system and the working well foundation pit to form an integral stress system. The top shield counterforce seat platform of the top shield starting structure of the application transmits force to the bottom plate of the working well foundation pit through the prestressed steel strands to form an integral stress system, provides a shield starting jacking thrust, and thus solves the problem of insufficient jacking thrust at the back of water or air in the top shield construction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel construction, in particular, to a top shield launching structure and a construction method thereof. BACKGROUND

[0002] With the rapid development of urban underground tunnel engineering, a series of problems such as repeated excavation of ground, collapse caused by excessive settlement, and tense ground traffic environment have been derived. The top shield technology is gradually favored because it integrates pipe jacking and shield tunneling, and combines the advantages of pipe jacking and shield technology. With the increasingly complex construction environment, the situation that the back is near water (or air) and cannot provide sufficient jacking force will be encountered in long-distance top shield construction. How to solve the problem of insufficient jacking force at the back near water (or air) is an urgent problem in the field of top shield engineering. SUMMARY

[0003] The present application provides a top shield launching structure to solve the technical problem of insufficient jacking force at the back near water (or air) in current long-distance top shield construction.

[0004] The present application also provides a top shield launching structure construction method, which adopts the above top shield launching structure.

[0005] According to one aspect of the present application, a top shield launching structure is provided for being arranged at the back near water or the back near air and providing jacking force for a top shield machine. The top shield launching structure comprises a working well foundation pit, an internal support system, and a counterforce seat system. The internal support system is arranged in the working well foundation pit to support the pit wall of the working well foundation pit. The counterforce seat system is arranged at the back of the working well foundation pit along the tunneling direction of the top shield machine. The counterforce seat system comprises a top shield counterforce seat platform and a prestressed reinforcement structure. The prestressed reinforcement structure comprises a fastening block and a prestressed steel strand. The first end of the prestressed steel strand is fixed on the top shield counterforce seat platform through the fastening block, and the second end of the prestressed steel strand is fixed on the bottom plate of the working well foundation pit. The height of the first end of the prestressed steel strand is higher than that of the second end and forms a tension angle relative to the bottom plate of the working well foundation pit. The prestressed steel strand is used to connect the counterforce seat system and the working well foundation pit to form an integral force system.

[0006] Further, the fastening block is a first tooth block and a second tooth block. The first end of the prestressed steel strand is anchored on the first tooth block, and the first tooth block is fixed on the top shield counterforce seat platform through anchoring. The second end of the prestressed steel strand is anchored on the second tooth block, and the second tooth block is fixed on the bottom plate of the working well foundation pit. The first tooth block and the second tooth block are used to tension and lock the prestressed steel strand.

[0007] Further, the long-distance shield launching structure further comprises a launching shaft foundation pit enclosure structure, which comprises a temporary fence and a water collecting ditch arranged on the ground, and a support pile and a water stop pile arranged underground, and a pile-to-pile support structure arranged on one side of the support pile and the water stop pile, and the support pile and the water stop pile are arranged alternately around the outer periphery of the working shaft foundation pit.

[0008] Further, the counterforce seat system further comprises a counterforce pile group, which is divided into two rows, the front row is a support pile and a counterforce pile, and the rear row is a counterforce pile, and the shield counterforce seat bearing platform is connected with the support pile and the counterforce pile and is supported and fixed by the support pile and the counterforce pile.

[0009] Further, the inner support system comprises a corbel, a reinforced concrete support structure and a steel support structure; the corbel is used to connect the support pile and the shield counterforce seat bearing platform into a whole; the reinforced concrete support structure is connected with the corbel; the steel support structure is arranged below the reinforced concrete support structure, and a plurality of steel support structures arranged in parallel in the up-down direction are arranged in the working shaft foundation pit wall.

[0010] Further, the reinforced concrete support structure comprises a concrete support and a concrete plate support, the concrete support comprises a first concrete support connecting the opposite sides of the working shaft foundation pit wall into a whole and a second concrete support connecting the adjacent sides of the working shaft foundation pit wall into a whole, and the concrete plate support is used to support the corner of the working shaft foundation pit wall.

[0011] The steel support structure comprises a steel support and a steel plate corner brace, the steel support comprises a first steel support connecting the opposite sides of the working shaft foundation pit wall into a whole and a second steel support connecting the adjacent sides of the working shaft foundation pit wall into a whole, and the steel plate corner brace is used to support the corner of the working shaft foundation pit wall.

[0012] Further, the inner support system further comprises a steel enclosing purlin, the steel enclosing purlin is installed on the pile-to-pile support structure, and the steel support structure is fixed in the working shaft foundation pit wall through the steel enclosing purlin.

[0013] Further, the working shaft foundation pit further comprises a working shaft main body structure, the working shaft main body structure comprises a bottom plate, a hidden column and an inner lining wall, a waterproof layer and a cushion layer are arranged in sequence below the bottom plate, and the hidden column is arranged around the working shaft and is used to improve the integrity of the working shaft main body structure.

[0014] Further, the working shaft foundation pit further comprises a shield pipe and a shield tunnel, and the shield pipe and the shield tunnel are arranged at the center position of the front face of the working shaft foundation pit in the tunneling direction of the shield machine.

[0015] According to another aspect of the present application, a shield launching structure construction method is also provided, which comprises the following steps:

[0016] (1) Level the site, construct retaining piles, water-stopping piles and counterforce piles; excavate the foundation pit, pre-bury the main body structure connecting steel bars and the crown beam connecting steel bars in the foundation pit, pre-bury the steel sleeves for positioning the prestressed steel strands, the first tooth block steel bars, pour and form the top shield counterforce seat bearing platform in the foundation pit;

[0017] (2) Continue to excavate the foundation pit, construct the pile top crown beam and the reinforced concrete support structure, excavate the earthwork in layers to the first steel support structure, construct the steel encasing purlin, backfill the fast-hardening fine stone concrete behind the encasing purlin, and excavate the earthwork in layers to the bottom plate of the foundation pit in a cycle until the last steel support structure;

[0018] (3) Construct the bottom plate, the second tooth block and the side wall and hidden column below the steel support structure, pre-bury the prestressed steel strands, anchor the two ends of the prestressed steel strands on the top shield counterforce seat bearing platform and the bottom plate of the working well foundation pit respectively, then perform the tensioning and anchoring process, and complete the construction of the prestressed reinforced structure.

[0019] The present application has the following beneficial effects:

[0020] In the counterforce seat system of the present application, the fastening block is effectively connected with the counterforce seat bearing platform by planting the steel bar on the top shield counterforce seat bearing platform, and the other fastening block is pre-buried in the bottom plate of the working well foundation pit, the counterforce seat system is connected with the working well foundation pit to form a whole through the prestressed steel strands, the top shield counterforce seat bearing platform transmits the force to the whole force system formed by the bottom plate and the second tooth block through the prestressed steel strands, so that the reverse tension of the prestressed steel strands offsets the jacking force received by the top shield counterforce seat bearing platform, and the back of the top shield counterforce seat bearing platform can still provide sufficient jacking force when the back is in the water or in the air, thereby solving the problem of insufficient jacking force at the back of the water (or in the air) in long-distance top shield construction.

[0021] In addition to the objects, features and advantages described above, the present application has other objects, features and advantages. The present application will be further described below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, and are incorporated in and constitute a part of this specification. The illustrations are shown to explain the present application and are not intended to limit the present application unduly. In the drawings:

[0023] Figure 1 The structure diagram of the top shield originating structure of the preferred embodiment of the present application;

[0024] Figure 2 The structure diagram of the top shield originating structure of the preferred embodiment of the present application; Figure 1 The sectional view of the top shield originating structure shown in the figure along A-A direction;

[0025] Figure 3 A planar schematic diagram of a prestressed reinforcement structure of a preferred embodiment of the present invention;

[0026] Figure 4 A planar schematic diagram of a shield launching shaft foundation pit concrete support of a preferred embodiment of the present invention;

[0027] Figure 5 A planar schematic diagram of a shield launching shaft foundation pit steel support of a preferred embodiment of the present invention;

[0028] Figure 6 A sectional schematic diagram of a shield launching shaft foundation pit enclosure structure of a preferred embodiment of the present invention;

[0029] Figure 7 A schematic diagram of a shield launching structure construction step of a preferred embodiment of the present invention;

[0030] Figure 8 A schematic diagram of a shield launching structure construction step of a preferred embodiment of the present invention;

[0031] Figure 9 A schematic diagram of a shield launching structure construction step of a preferred embodiment of the present invention;

[0032] Figure 10 A schematic diagram of a shield launching structure construction step of a preferred embodiment of the present invention;

[0033] Figure 11 A schematic diagram of a shield launching structure construction step of a preferred embodiment of the present invention;

[0034] Figure 12 A schematic diagram of a shield launching structure construction step of a preferred embodiment of the present invention;

[0035] Figure 13 A schematic diagram of a shield launching structure construction step of a preferred embodiment of the present invention;

[0036] Figure 14 A schematic diagram of a shield launching structure construction step of a preferred embodiment of the present invention.

[0037] Wherein: 1-steel mesh; 2-early strength shotcrete; 3-water interception ditch; 4-enclosure pile; 5-water stop pile; 6-crown beam; 7-concrete support; 8-steel support; 9-counterforce pile; 10-top shield counterforce seat pile cap; 11-prestressed steel strand; 12-lining wall; 13-concealed column; 14-bottom plate; 15-cushion layer; 16-waterproof layer; 17-first tooth block; 18-second tooth block; 19-steel sleeve; 20-anchor; 21-anchored rebar; 22-top shield pipe; 23-concrete slab support; 24-retaining wall; 25-temporary guardrail; 26-steel cross support; 27-inter-pile support; 28-top shield tunnel; 29-steel enclosure purlin; 30-steel plate angle support. DETAILED DESCRIPTION

[0038] The embodiments of the present application will be described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways as defined and covered by the following.

[0039] Reference Figures 1 to 6 , the first aspect of the embodiments of the present application provides a top shield starting structure for being arranged at the back of water or the back of empty space and providing a jacking force for a top shield machine, the top shield starting structure comprising a working well foundation pit, an internal support system and a counterforce seat system; the internal support system is arranged in the working well foundation pit for supporting the working well foundation pit wall; the counterforce seat system is arranged at the back of the working well foundation pit along the advancing direction of the top shield machine, the counterforce seat system comprises a top shield counterforce seat pile cap 10 and a prestressed reinforcement structure, the prestressed reinforcement structure comprises a fastening block and a prestressed steel strand 11, the first end of the prestressed steel strand 11 is fixed on the top shield counterforce seat pile cap 10 through the fastening block, the second end of the prestressed steel strand 11 is fixed on the bottom plate of the working well foundation pit through the fastening block, the height of the first end of the prestressed steel strand 11 is higher than the second end and forms a tension angle relative to the bottom plate of the working well foundation pit, and the prestressed steel strand 11 is used to connect the counterforce seat system and the working well foundation pit to form an overall force system.

[0040] The prestressed reinforcing structure is arranged in the counterforce seat system, the connection between components is reinforced through the prestressed reinforcing structure, the connection and anchoring between the tooth block and the counterforce seat platform, the connection and anchoring between the tooth block and the bottom plate 14 of the foundation pit are ensured through the form of the planted steel bar 21, the reserved anchoring steel bar and the like, and the prestressed tension of the high-strength steel strand is controlled, so that sufficient and reliable shield thrust is provided under the premise of ensuring the safety of the structure. The height of the first end of the prestressed steel strand 11 is higher than the height of the second end, the force on the shield counterforce seat platform 10 is transmitted to the foundation pit of the working well through the prestressed steel strand 11, and the shield launching and jacking thrust is provided. Specifically, the size of the counterforce seat platform is related to the installation angle of the prestressed steel strand 11 and needs to be determined through calculation to adapt to different working environments and provide sufficient shield thrust. The long-distance shield launching structure of the back of the invention is particularly suitable for the working environment of the metro shield launching well, wherein the plane size of the working well is generally small, the tunnel is deeply buried, the geological conditions are complex, and the construction difficulty under the condition of large buried depth and complex geology can be effectively solved through the split launching mode. This structure can realize the smooth launching of the shield machine in a limited space, ensure the stability of the end head stratum of the launching well, lay a solid foundation for subsequent safe construction, realize the adaptability to complex geological conditions through optimized design, and enhance the feasibility and safety of the project.

[0041] Reference Figure 1 and Figure 3 In the embodiment of the invention, the prestressed reinforcing structure further comprises a steel sleeve 19 and an anchor 20, the prestressed steel strand 11 passes through the steel sleeve 19, the fastening block is a first tooth block 17 and a second tooth block 18, the first end of the prestressed steel strand 11 is anchored on the first tooth block 17, the first tooth block 17 is fixed on the shield counterforce seat platform 10 through the planted steel bar 21, the second end of the prestressed steel strand 11 is anchored on the second tooth block 18, and the second tooth block 18 is fixed on the bottom plate 14 of the working well foundation pit, and the first tooth block 17 and the second tooth block 18 are used for tensioning and locking the prestressed steel strand 11. The second tooth block 18 is a reserved anchoring steel bar during the construction of the bottom plate 14 of the working well foundation pit. The steel sleeve 19 is pre-buried before the counterforce seat platform, the lining wall 12 of the working well foundation pit and the second tooth block 18 are poured, the anchor 20 is pre-buried before the tooth block is poured, and the second tooth block 18 is poured together with the counterforce seat and the bottom plate 14 of the working well. After the second tooth block 18 reaches the design strength, the steel strand is threaded, tensioned and anchored, and the prestressed reinforcing structure is formed.

[0042] The working principle of the prestressed reinforcement structure is as follows: the second tooth block 18 serves as an anchoring end of the prestressed steel strand 11, passes through the pre-buried steel sleeve 19, and is convenient for later threading of the prestressed steel strand 11 and post-tensioning, and the second tooth block 18 provides strong anchoring for the prestressed steel strand 11; the first tooth block 17 provides a tensioning and locking platform for the prestressed steel strand 11, and the first tooth block 17 forms an integral body with the top shield counterforce seat pile cap 10 through the later-embedded steel bar 21, when the prestressed steel strand 11 is tensioned, the first tooth block 17 is tightly pressed by the anchorage device 20, and the prestressed steel strand 11 is tensioned and locked by temporarily installing a through-type hydraulic jack, a tool anchor and a backing plate and the like on the prestressed steel strand 11, and the force is transmitted to the working well foundation bottom plate 14 through the prestressed steel strand 11.

[0043] The top shield counterforce seat pile cap 10 is connected with a row of counterforce piles 9 and a row of enclosure piles 4 at the lower part, and a pressure is pre-applied to the top shield counterforce seat pile cap 10 through the prestressed steel strand 11 at the upper part, so that the top shield counterforce seat pile cap 10 can provide a safe, effective and reliable support counterforce during the construction of the top shield. Part of the counterforce is used to offset the pressure pre-applied to the counterforce seat pile cap by the prestressed steel strand 11, and part of the counterforce is transmitted to the counterforce piles 9. Due to the use of the prestressed steel strand 11, the stress model of the counterforce piles 9 is changed from a cantilever beam stress to a statically indeterminate beam stress, so that the stress of the counterforce piles 9 is more reasonable, and the overall safety of the structure is improved.

[0044] In the counterforce seat system of the application, the embedded steel bar 21 is arranged on the top shield counterforce seat pile cap 10 to realize the effective connection between the first tooth block 17 and the counterforce seat pile cap, and the second tooth block 18 is pre-buried in the bottom plate 14 of the working well foundation, so that the counterforce seat system and the working well foundation are connected to form an integral body through the prestressed steel strand 11, the force is transmitted to the integral stress system formed by the bottom plate 14 and the second tooth block 18 through the prestressed steel strand 11 of the top shield counterforce seat pile cap 10, so that the reverse tension of the prestressed steel strand 11 offsets the jacking force received by the top shield counterforce seat pile cap, the back of the top shield counterforce seat pile cap does not need to be supported, and the back of the top shield counterforce seat pile cap can still provide sufficient jacking force when the back is near water or in the air, so that the problem of insufficient jacking force at the back near water (or in the air) in long-distance top shield construction is solved.

[0045] Reference Figure 6In the embodiment of the present application, the long-distance shield launching structure further comprises a launching shaft foundation enclosure, which comprises temporary guardrails 25, a water interception ditch 3, a retaining wall 24, enclosure piles 4, water stop piles 5, and pile-to-pile support 27, pile-to-pile anchor jet support structures, the enclosure piles 4 and the water stop piles 5 are arranged alternately around the outer periphery of the working shaft foundation in sequence, and the pile-to-pile support 27 structure is arranged on one side of the enclosure piles 4 and the water stop piles 5. Part of the enclosure piles 4 under the shield counterforce seat pile cap 10 act as counterforce piles 9 to provide part of the counterforce. The retaining wall 24 is located above the crown beam 6, which functions to prevent surface water from flowing into the foundation pit; the temporary guardrails 25 and the water interception ditch 3 at the edge of the foundation pit are used for safety protection and interception, guidance, and collection of surface water, respectively; the enclosure piles 4 are made of cast-in-situ bored piles, which function to bear the earth lateral pressure after the launching shaft foundation is excavated; the pile-to-pile support 27 is made of a structure of steel mesh 1 plus early-strength sprayed concrete 2 to limit the collapse of the soil between the piles; the water stop piles 5 are made of high-pressure rotary jet piles of cement mortar to prevent the softening and collapse of the soil around the foundation pit due to underground water; and the soil behind the piles of the shield launching line is reinforced by high-pressure rotary jet piles to improve the integrity of the enclosure piles 4 and the soil behind the piles, so as to realize the pile-soil collaborative stress during shield construction.

[0046] In the embodiment of the present application, the counterforce seat system further comprises a counterforce pile 9 group, which is divided into two rows, the front row being the enclosure piles 4 acting as counterforce piles 9, and the back row being counterforce piles 9, the pile diameter of the back row counterforce piles 9 being 1.2-1.5 times that of the front row, the shield counterforce seat pile cap 10 being connected with the enclosure piles 4 and the counterforce piles 9 and being supported and fixed by the enclosure piles 4 and the counterforce piles 9, the whole counterforce seat system being stressed during shield construction, and the counterforce pile 9 group being used to disperse the counterforce of the shield counterforce seat pile cap 10.

[0047] Referring to Figure 6 In the embodiment of the present application, the internal support system comprises a crown beam 6, a reinforced concrete support structure, and a steel support structure; the crown beam 6 is used to connect the enclosure piles 4 and the shield counterforce seat pile cap into a whole; the reinforced concrete support structure is connected with the crown beam 6; the steel support structure is arranged below the reinforced concrete support structure, and a plurality of steel support structures arranged in parallel in the up-down direction are arranged in the working shaft foundation pit wall. The internal support system is used to provide firm support force for the foundation pit. After the construction of the enclosure piles 4 is completed and the design strength is reached, the enclosure piles 4 are connected into a whole through the crown beam 6, the steel reinforcement of the first reinforced concrete soil support is pre-buried in the crown beam 6 and connected with the stress steel reinforcement of the crown beam 6 to ensure the integrity of the internal support system. A plurality of steel support structures are reasonably arranged according to the actual engineering, and the steel support structure is composed of round steel pipes, steel enclosing purlins 29, nodes, rib plates, enclosing purlin joints, support corbels, and fixing members, wherein the height range of the contact between the steel enclosing purlins 29 and the enclosure piles 4 is filled with fast-hardening fine aggregate concrete to ensure close contact between the enclosing purlins and the piles and uniform force transmission.

[0048] Referring to Figure 4 and Figure 5 Optionally, the reinforced concrete support structure comprises a concrete support 7 and a concrete plate support 23, the concrete support 7 comprises a first concrete support connecting opposite sides of the shaft foundation pit wall into a whole, a second concrete support connecting adjacent sides of the shaft foundation pit wall into a whole, and the concrete plate support 23 is used for supporting the corner of the shaft foundation pit wall; the steel support structure comprises a steel support 8 and a steel plate corner support 30, the steel support 8 comprises a first steel support connecting opposite sides of the shaft foundation pit wall into a whole, a second steel support connecting adjacent sides of the shaft foundation pit wall into a whole, and the steel plate corner support is used for supporting the corner of the shaft foundation pit wall, and the steel support 8 and the steel plate corner support 30 are correspondingly arranged below the concrete support 7 and the concrete plate support 23, respectively, for supporting the opposite sides, adjacent sides and corners of the shaft foundation pit wall.

[0049] Optionally, the inner support system further comprises a steel enclosing purlin 29, the steel enclosing purlin 29 is installed on the pile interval support 27 structure, and the steel support structure is fixed in the shaft foundation pit through the steel enclosing purlin 29. The pile interval support 27 structure is composed of the steel mesh 1 and the early-strength sprayed concrete 2, and is mainly used for preventing water and soil loss between piles.

[0050] In the embodiment of the present application, the shaft foundation pit further comprises a shaft main body structure, the shaft main body structure comprises a bottom plate 14, a hidden column 13 and an inner lining wall 12, the bottom plate 14 is sequentially provided with a waterproof layer 16 and a cushion layer 15 below, the hidden column 13 is arranged around the shaft, and is used for connecting the shaft foundation pit enclosure structure and the shaft foundation pit, the hidden column 13 and the inner lining wall 12 are constructed together, the cushion layer 15 and the waterproof layer 16 are constructed first after the foundation pit is excavated to the design elevation, then the steel bar binding of the bottom plate 14, the steel bar pre-embedding of the hidden column 13 and the concrete pouring are performed, and then the steel bar binding and the concrete pouring of the hidden column 13 and the inner lining wall 12 are performed, so that the shaft foundation pit is formed.

[0051] Further, the shaft foundation pit further comprises a top shield pipe 22 and a top shield tunnel 28, and the top shield pipe 22 and the top shield tunnel 28 are arranged at the center of one side of the shaft foundation pit.

[0052] Referring to Figures 7 to 14 According to the embodiment of still another aspect of the present application, a construction method of a long-distance top shield shaft originating structure at the back of water is provided, which comprises the following steps:

[0053] (1) leveling the site, constructing a water intercepting ditch 3 and a temporary guardrail 25, drilling holes on the ground, and constructing a reinforced rotary jet pile, a water stop pile 5, an enclosure pile 4 and a counterforce pile 9; referring to Figure 7 ;

[0054] (2) After the enclosure and counterforce pile 9 reach the design requirements, excavate to the bottom of the counterforce seat base, and perform counterforce seat reinforcement installation and pre-embed working well structure connecting reinforcement and corbel 6 connecting reinforcement, steel sleeve 19, and tooth block reinforcement to ensure that the counterforce seat base is connected with the corbel 6 and working well foundation pit to form a whole, and to provide a tension locking platform (first tooth block 17) for the prestressed steel strand 11, and then pour the counterforce seat base;

[0055] (3) Excavate the soil to the bottom elevation of the corbel 6 and reinforced concrete support structure, construct the pile top corbel 6 and reinforced concrete support structure of the enclosure pile 4, and after the counterforce seat, corbel 6, and reinforced concrete support structure reach the design strength, excavate the soil in layers to 500 mm below the center line of the first steel support structure, and spray the pit wall concrete facing while excavating to prevent water and soil loss between piles; install the steel support structure after constructing the steel enclosure purlin 29, and backfill the quick-hardening fine aggregate concrete behind the enclosure purlin to ensure that there is a large enough contact surface between the enclosure purlin and the enclosure pile 4, so that the force transmission is more uniform and the structure is more reasonably stressed; install the steel support 8 and tighten after the fine aggregate concrete reaches the design strength; excavate in layers to the bottom of the foundation pit after the last steel support 8 is constructed; manually excavate the 300 mm undisturbed soil, and spray the pit wall concrete facing while excavating; see Figure 8 ;

[0056] (4) Pour the bottom plate cushion 15, lay the waterproof layer 16, construct the bottom plate 14 (pre-embed the reinforcement of the hidden column 13 and the tooth block reinforcement), and pre-embed the second tooth block 18 and the side wall and hidden column 13 below the steel support structure. After the bottom plate 14 and the side wall concrete reach the design strength, construct the replacement support steel pipe, remove the steel support 8, and make the steel replacement support 26 rest on the newly poured side wall, so as to facilitate the subsequent construction of the side wall and hidden column 13 above; continue to construct the working well side wall and temporary side wall to the bottom of the top reinforced concrete support structure, and remove the replacement support steel pipe after the side wall concrete curing reaches the design strength; remove the reinforced concrete support structure, construct the remaining side wall, and after the main structure reaches the design strength, remove the reinforced concrete formwork to complete the construction of the remaining side wall; after the main structure reaches the design strength, perform the prestressed steel strand 11 threading, tensioning, and anchoring process to complete the construction of the prestressed reinforcement structure; see Figures 9 to 12 ;

[0057] (5) the bottom plate 14 in the well is loaded with weight to prevent the working well from floating up during tunnel excavation; the tunnel top shield equipment is hoisted, and the top shield thrust provided by the counterforce seat system pushes forward (drills) ; then the tunnel pipe section (piece) is hoisted; after the top shield completes construction, the weight is removed, and the temporary side wall (the temporary side wall functions as a temporary soil retaining wall and is connected with the end wall and the counterforce seat platform to form a whole and bear force together) is removed, the well structure is constructed, and the working well structure top plate is constructed; then part of the counterforce seat concrete structure exposed on the ground is removed; the working well top plate is covered with earth and backfilled, and the slope is restored; the enclosure is removed, and the water interception ditch 3 is backfilled, see Figures 13 to 14 .

[0058] The present application can realize smooth launching of the shield machine in limited space, and through specific process and technical measures, the stability of the end head stratum of the launching well is ensured, which lays a solid foundation for subsequent safe construction. Through optimized design, adaptability to complex geological conditions is realized, and the feasibility and safety of the project are enhanced.

[0059] The basic principles, main features and advantages of the present application are shown and described above. The technicians in this industry should be clear that the present application is not limited by the above examples, and the above examples and descriptions are only the basic principles of the present application. Without departing from the design concept and scope of the present application, the present application can be further improved according to specific application conditions, and these improvements are required to fall within the scope of the present application. The scope of protection of the present application is the appended claims and their equivalents.

Claims

1. A top-shield launching structure, used to be positioned with its rear facing water or air and to provide thrust to a top-shield launcher, characterized in that, The top shield launching structure includes a working shaft pit, an internal support system, and a reaction seat system. The working shaft pit provides a site for the installation of the top shield machine. The internal support system is located inside the working shaft pit and is used to support the pit wall. The reaction seat system is located on the back side of the working shaft pit along the tunneling direction of the top shield machine. The reaction seat system includes a top shield reaction seat platform (10) and a prestressed reinforcement structure. The prestressed reinforcement structure includes fastening blocks and prestressed steel strands (11). The first end of the prestressed steel strand (11) is fixed to the top shield reaction seat platform (10) by fastening blocks. The second end of the prestressed steel strand (11) is fixed to the bottom plate of the working shaft pit by fastening blocks. The height of the first end of the prestressed steel strand (11) is higher than that of the second end and forms a tension angle with respect to the bottom plate of the working shaft pit. The prestressed steel strand (11) is used to connect the reaction seat system with the working shaft pit to form an integrated force-bearing system. The fastening block includes a first toothed block (17) and a second toothed block (18). The first end of the prestressed steel strand (11) is anchored on the first toothed block (17), and the first toothed block (17) is fixed on the top shield reaction seat bearing (10) by a rebar (21). The second end of the prestressed steel strand (11) is anchored on the second toothed block (18), and the second toothed block (18) is fixed on the bottom plate (14) of the working well pit. The first toothed block (17) and the second toothed block (18) are used to tension and lock the prestressed steel strand (11).

2. The top shield launching structure according to claim 1, characterized in that, The top shield launching structure also includes a launching well pit retaining structure, which includes a temporary guardrail (25) and a water interception ditch (3) on the ground, and retaining piles (4) and water-stopping piles (5) underground. A pile support structure is provided on one side of the retaining piles (4) and the water-stopping piles (5). The retaining piles (4) and the water-stopping piles (5) are arranged alternately around the outer perimeter of the working well pit.

3. The top shield launching structure according to claim 2, characterized in that, The reaction seat system also includes a reaction pile group, which is divided into two rows. The front row is the retaining pile (4), and the rear row is the reaction pile (9). The top shield reaction seat platform (10) is connected to the retaining pile (4) and the reaction pile (9) respectively and is supported and fixed by the retaining pile (4) and the reaction pile (9).

4. The top shield launching structure according to claim 2, characterized in that, The internal support system includes a cap beam (6), a reinforced concrete support structure, and a steel support structure; the cap beam (6) is used to connect the retaining piles (4) and the top shield reaction seat platform (10) into a whole; the reinforced concrete support structure is connected to the cap beam (6); the steel support structure is set below the reinforced concrete support structure, and several parallel steel support structures are set in the pit wall of the working well foundation pit.

5. The top shield launching structure according to claim 4, characterized in that, The reinforced concrete support structure includes a concrete support (7) and a concrete slab support (23). The concrete support (7) includes a first concrete support that connects the opposite sides of the working well pit wall into a whole and a second concrete support that connects the adjacent sides of the working well pit wall into a whole. The concrete slab support (23) is used to support the corner of the working well pit wall. The steel support structure includes a steel support (8) and a steel plate corner brace (30). The steel support (8) includes a first steel support that connects the opposite sides of the working well pit wall into a whole and a second steel support that connects the adjacent sides of the working well pit wall into a whole. The steel plate corner brace (30) is used to support the corner of the working well pit wall.

6. The top shield launching structure according to claim 5, characterized in that, The internal support system also includes a steel waler (29), which is installed on the pile support structure. The steel support structure is supported in the working well pit by the steel waler (29).

7. The top shield launching structure according to claim 1, characterized in that, The working well foundation pit is also provided with a main structure of the working well, which includes a base plate (14), a hidden column (13) and an inner lining wall (12). A waterproof layer (16) and a cushion layer (15) are provided below the base plate (14) in sequence. The hidden column (13) is set around the working well to improve the integrity of the main structure of the working well.

8. The top shield launching structure according to claim 7, characterized in that, The working shaft foundation pit also includes a top shield pipe (22) and a top shield tunnel (28), which are located at the center of the front of the working shaft foundation pit along the tunneling direction of the top shield machine.

9. A method for constructing a top shield launching structure, characterized in that, For constructing the top shield launching structure as described in any one of claims 1-8, the construction method of the top shield launching structure includes the following steps: (1) Level the site, construct retaining piles (4), water-stopping piles (5) and reaction piles (9); excavate the foundation pit, pre-embed the main structure connecting steel bars and crown beam (6) connecting steel bars in the foundation pit, and pre-embed the steel sleeve (19) for positioning the prestressed steel strand (11) and the first tooth block steel bar, and pour the top shield reaction seat foundation in the foundation pit; (2) Continue to excavate the foundation pit, construct the top cap beam (6) and reinforced concrete support structure, then excavate the soil layer by layer to the first steel support structure, construct the steel waler (29), and fill the back of the waler with quick-hardening fine stone concrete, excavate in a cycle to the last steel support structure, and finally excavate the soil layer by layer to the bottom slab of the foundation pit. (3) Construct the base plate (14), the reserved second tooth block (18) and the side walls and hidden columns (13) below the steel support structure, and then thread the prestressed steel strands (11) through them. Anchor the two ends of the prestressed steel strands to the top shield reaction seat and the base plate of the working well pit respectively. Then carry out the tensioning and anchoring process to complete the construction of the prestressed reinforced structure.

Images