Shield tunnel construction method and tunnel structure

Abstract

The present invention discloses a shield tunnel construction method and tunnel structure, which relates to the technical field of tunnel construction. The shield tunnel construction method includes the following steps: performing shield construction to form a tunnel section; performing local reinforcement in the tunnel section to form a tunnel subsection after local reinforcement; the tunnel subsection includes a middle section and reinforcement sections located at both ends of the middle section; constructing in a vertical direction within an annular area to form an annular support structure; the coverage of the annular area includes the middle section and partially includes the reinforcement section; constructing in a vertical direction within the area enclosed by the support structure to form a working well; removing the reinforcement structure in the reinforcement section and removing the structure in the support structure located within the reinforcement section to make the tunnel section horizontally connected. The present invention adopts a construction method of first constructing the tunnel and then constructing the working well, thereby significantly reducing the impact of external environments such as land acquisition and demolition, pipeline relocation, etc., and effectively reducing the risk of construction delays.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel construction, and in particular to a shield tunnel construction method and a tunnel structure. Background Art

[0002] Power shield tunnels are a crucial component of urban underground power facilities, requiring complex geological conditions and stringent construction precision and safety requirements. Currently, shield tunnel launch and terminal shafts can be located at distances greater than 2 km during shield tunnel construction, while meeting technical construction requirements and improving project economics. However, to accommodate the layout of power tunnel maintenance equipment and fire safety requirements, power shafts are typically located at intervals of 400 to 600 meters. These shafts typically serve as both the launch and terminal shafts for shield tunnels.

[0003] In traditional urban shield tunnel construction, the "shaft first, tunnel later" construction method is usually adopted, that is, the shield starting shaft and the final shaft are constructed first, and shield construction is carried out when the shield shaft is ready. The construction of the shield shaft is generally completed by the open-cut method. The shield shaft section uses a shield machine to excavate the tunnel underground, and soil treatment and tunnel support are carried out simultaneously. Therefore, in the conventional construction process, the power shaft must be completed before the subsequent shield section can be constructed. Therefore, the construction time of the power shaft is a key control node of the project and has a significant impact on the construction period of the entire project.

[0004] However, power tunnels are generally constructed in urban core areas or renewal areas. Along the tunnel route, the construction area often faces a large number of relocation and compensation issues for residents, enterprises, and institutions. These issues require a lot of time to complete complex coordination work. If the land acquisition and demolition progress is seriously delayed, the construction of the power shaft will not proceed as planned, which will in turn affect the overall construction progress of the power tunnel. In addition, due to the complexity of urban underground pipelines, including various types such as electricity, communications, gas, water supply and drainage, the relocation of these pipelines requires coordination with numerous units, increasing the difficulty and uncertainty of construction. According to engineering experience, according to the traditional "well first, tunnel later" construction method, these complex external conditions often prevent the construction of the working shaft from proceeding as planned, which in turn causes the shield construction progress of the subsequent tunnel section to lag behind, greatly affecting the construction period, while increasing project costs and having adverse social impacts. Summary of the Invention

[0005] The main purpose of the present invention is to propose a shield tunnel construction method, which aims to solve the problem that the traditional power shield tunnel construction method using the "well first, tunnel later" method is easily affected by external conditions such as relocation compensation and pipeline relocation, resulting in delayed construction progress.

[0006] To achieve the above object, the shield tunnel construction method proposed in the present invention comprises the following steps:

[0007] Conduct shield construction to form tunnel sections;

[0008] Performing local reinforcement within the tunnel section to form a locally reinforced tunnel subsection; wherein the tunnel subsection includes a middle section and reinforced sections located at both ends of the middle section;

[0009] Constructing in a vertical direction within the annular area to form an annular support structure; wherein the coverage of the annular area includes the middle section and partially includes the reinforcement section;

[0010] Conducting construction in a vertical direction within the area enclosed by the support structure to form a working pit;

[0011] The reinforcement structure in the reinforcement section is removed, and the structure of the support structure located within the reinforcement section is removed to make the tunnel section transversely connected.

[0012] In one embodiment, the step of performing shield construction to form a tunnel section includes:

[0013] Performing shield tunneling construction on the tunnel section using a shield tunneling machine;

[0014] During the shield tunneling process, a shield tunneling machine is used to lay tunnel segments on the inner wall of the tunnel section.

[0015] In one embodiment, the step of locally reinforcing the tunnel section to form a locally reinforced tunnel subsection includes:

[0016] The portion of the tunnel section where the working pit is to be constructed is used as a specific section, and a plurality of steel templates are used to respectively block both ends of the specific section, and the steel templates are used to provide support for the tunnel;

[0017] The filling body is poured into the interior of the steel formwork by using a grouting steel pipe that passes through the steel formwork.

[0018] In one embodiment, the filling body is a lightweight foam concrete material; and / or, each of the steel formworks is provided with at least two grouting steel pipes, and the vertical spacing between two adjacent grouting steel pipes is in the range of 0.9 to 1.1 m.

[0019] In one embodiment, the step of constructing in a vertical direction within the annular area to form an annular support structure includes:

[0020] removing the tunnel segments on the inner walls of the tunnel sub-intervals within the annular area in blocks;

[0021] constructing hard bite piles at both ends of the middle section in a vertical direction, and extending the hard bite piles in a vertical direction to the ground to form the support structure;

[0022] constructing on the inner side of the hard bite pile to form a top beam;

[0023] A first double-tube rotary jet pile is constructed along the outer ring of the hard bite pile at the top of the hard bite pile, and a second double-tube rotary jet pile is constructed along the inner ring of the hard bite pile at the top of the hard bite pile.

[0024] In one embodiment, after the steps of constructing a first double-tube rotary grouting pile along the outer ring of the hard bite pile at the top of the hard bite pile and constructing a second double-tube rotary grouting pile along the inner ring of the hard bite pile at the top of the hard bite pile, the method further comprises:

[0025] constructing along the annular top of the hard bite pile to form a retaining wall;

[0026] Construction is carried out along the outer periphery of the first double-tube jet grouting pile to form a water intercepting ditch.

[0027] In one embodiment, the thickness of the first double-tube jet grouting pile is ≥1.5m;

[0028] And / or, the thickness of the second double-tube jet grouting pile is ≥1.5m;

[0029] And / or, the hard bite piles are configured as reinforced concrete piles.

[0030] In one embodiment, the step of constructing in a vertical direction within the area enclosed by the support structure to form a working pit includes:

[0031] excavating earth in a vertical direction within the area enclosed by the supporting structure, cleaning the base of the earth, and laying a structural base plate on the base;

[0032] Tie steel bars along the inner wall of the support structure and install end wall formwork, and pour concrete in the end wall formwork to form the main structural end wall of the working pit;

[0033] Reinforcement is tied to the top of the end wall of the main structure and a top cover formwork is installed, and concrete is poured into the top cover formwork to form the top cover of the working pit.

[0034] In one embodiment, a fine stone concrete protective layer at the upper layer and a concrete cushion layer at the lower layer are laid below the structural base plate.

[0035] The present invention also provides a tunnel structure, which is constructed using the above-mentioned shield tunnel construction method.

[0036] The technical solution of the present invention adopts a shield tunnel construction method, firstly, shield construction is carried out to form a tunnel section; local reinforcement is carried out in the tunnel section to form a tunnel sub-section after local reinforcement; wherein, the tunnel sub-section includes a middle section and reinforcement sections located at both ends of the middle section; construction is carried out in a vertical direction within the annular area to form an annular support structure; wherein, the coverage range of the annular area includes the middle section and partially includes the reinforcement section; construction is carried out in a vertical direction within the area enclosed by the support structure to form a working shaft; the reinforcement structure in the reinforcement section is removed, and the structure located in the reinforcement section of the support structure is removed to make the tunnel section horizontally connected.

[0037] The technical solution of the present invention adopts a "tunnel first, well later" construction method, that is, a construction method in which a tunnel is constructed first and a working well is constructed later. In the construction of urban power shield tunnels, the "tunnel first, well later" construction method can construct the tunnel section before constructing the working well, thereby avoiding the problem of delaying the construction progress of the working well due to external factors such as land acquisition and demolition, pipeline relocation, etc. in the traditional "well first, tunnel later" construction method, which leads to delays in the construction progress of subsequent tunnel sections. This effectively reduces the risk of construction delays caused by changes in the external environment.

[0038] In addition, the traditional "well first, tunnel later" construction method often requires the shield machine to wait for the construction of the working well to be completed before starting to construct the tunnel section, which to a certain extent limits the utilization efficiency of the shield machine; while the "tunnel first, well later" construction method adopted in the present invention avoids the shield machine's idleness, allowing the shield machine to excavate the tunnel section first, which can significantly shorten the overall construction period of urban power tunnels. It can not only reduce construction costs and shorten construction periods, but also ensure the safety and stability of the urban power tunnel path plan, providing a solid guarantee for the reliable transmission of urban power.

[0039] Moreover, the traditional "well first, tunnel later" construction method requires pre-setting the spacing between different working wells before constructing the tunnel section, which may result in a shorter spacing between the working wells and a shield tunneling machine needing to enter and exit the wells more frequently during the shield tunneling process; while the present invention adopts the "tunnel first, well later" construction method, the starting well, the terminal well and other working wells can be set at long distances according to the conditions of the tunnel section, thereby reducing the number of times the shield tunneling machine enters and exits the well, reducing construction risks, alleviating the impact of geological conditions, and ensuring construction safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0041] Figure 1 A schematic diagram of a process flow of an embodiment of a shield tunnel construction method provided by the present invention;

[0042] Figure 2 A schematic diagram of the construction process of an embodiment of the shield tunnel construction method provided by the present invention;

[0043] Figure 3 This is a structural schematic diagram of an embodiment of the tunnel structure provided by the present invention.

[0044] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0046] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0047] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0048] Power shield tunnels are a crucial component of urban underground power facilities, requiring complex geological conditions and stringent construction precision and safety requirements. Currently, shield tunnel launch and terminal shafts can be located at distances greater than 2 km during shield tunnel construction, while meeting technical construction requirements and improving project economics. However, to accommodate the layout of power tunnel maintenance equipment and fire safety requirements, power shafts are typically located at intervals of 400 to 600 meters. These shafts typically serve as both the launch and terminal shafts for shield tunnels.

[0049] In traditional urban shield tunnel construction, the "shaft first, tunnel later" construction method is usually adopted, that is, the shield starting shaft and the final shaft are constructed first, and shield construction is carried out when the shield shaft is ready. The construction of the shield shaft is generally completed by the open-cut method. The shield shaft section uses a shield machine to excavate the tunnel underground, and soil treatment and tunnel support are carried out simultaneously. Therefore, in the conventional construction process, the power shaft must be completed before the subsequent shield section can be constructed. Therefore, the construction time of the power shaft is a key control node of the project and has a significant impact on the construction period of the entire project.

[0050] However, power tunnels are generally constructed in urban core areas or renewal areas. Along the tunnel route, the construction area often faces a large number of relocation and compensation issues for residents, enterprises, and institutions. These issues require a lot of time to complete complex coordination work. If the land acquisition and demolition progress is seriously delayed, the construction of the power shaft will not proceed as planned, which will in turn affect the overall construction progress of the power tunnel. In addition, due to the complexity of urban underground pipelines, including various types such as electricity, communications, gas, water supply and drainage, the relocation of these pipelines requires coordination with numerous units, increasing the difficulty and uncertainty of construction. According to engineering experience, according to the traditional "well first, tunnel later" construction method, these complex external conditions often prevent the construction of the working shaft from proceeding as planned, which in turn causes the shield construction progress of the subsequent tunnel section to lag behind, greatly affecting the construction period, while increasing project costs and having adverse social impacts.

[0051] The invention provides a shield tunnel construction method.

[0052] See also Figure 1 In the first embodiment of the present invention, the shield tunnel construction method includes steps S10 to S50:

[0053] Step S10: Perform shield construction to form a tunnel section;

[0054] Step S20: locally reinforce the tunnel section to form a locally reinforced tunnel subsection; wherein the tunnel subsection includes a middle section and reinforced sections located at both ends of the middle section;

[0055] It should be noted that there are various options for local reinforcement of tunnel sections. For example, anchor reinforcement can be used, by drilling holes in the tunnel section's inner wall, inserting anchors, and then grouting them. Other options include soil nailing walls and steel arch reinforcement. The specific local reinforcement method can be selected based on actual needs and is not limited here.

[0056] Step S30: constructing in a vertical direction within the annular area to form an annular support structure; wherein the coverage of the annular area includes the middle section and partially includes the reinforcement section;

[0057] It should be noted that the support structure extends vertically from the tunnel section to the ground to form an effective support effect.

[0058] Step S40, constructing in a vertical direction within the area enclosed by the support structure to form a working pit;

[0059] It should be noted that the working shaft also extends vertically from the tunnel section to the ground.

[0060] Step S50: dismantle the reinforcement structure in the reinforcement section, and dismantle the structure of the support structure located in the reinforcement section, so as to make the tunnel section transversely connected.

[0061] It should be noted that the support structure has a part located inside the reinforcement section and another part located outside the reinforcement section. In order to allow the tunnel section to be horizontally connected, the part of the support structure located inside the reinforcement section needs to be demolished, while the other part of the support structure located outside the reinforcement section can be retained so that it can continue to play a supporting role.

[0062] In the first embodiment of the present invention, by adopting the "tunnel first, well later" construction method, that is, first constructing the tunnel and then constructing the working well, in the construction of urban power shield tunnels, the "tunnel first, well later" construction method can construct the tunnel section before constructing the working well, thereby avoiding the problem of delaying the construction progress of the working well due to external environments such as land acquisition and demolition, pipeline relocation, etc. in the traditional "well first, tunnel later" construction method, which leads to delays in the construction progress of subsequent tunnel sections, and effectively reduces the risk of construction delays caused by changes in the external environment.

[0063] In addition, the traditional "well first, tunnel later" construction method often requires the shield machine to wait for the construction of the working well to be completed before starting to construct the tunnel section, which to a certain extent limits the utilization efficiency of the shield machine; while the "tunnel first, well later" construction method adopted in the present invention avoids the shield machine's idleness, allowing the shield machine to excavate the tunnel section first, which can significantly shorten the overall construction period of urban power tunnels. It can not only reduce construction costs and shorten construction periods, but also ensure the safety and stability of the urban power tunnel path plan, providing a solid guarantee for the reliable transmission of urban power.

[0064] Moreover, the traditional "well first, tunnel later" construction method requires pre-setting the spacing between different working wells before constructing the tunnel section, which may result in a shorter spacing between the working wells and a shield tunneling machine needing to enter and exit the wells more frequently during the shield tunneling process; while the present invention adopts the "tunnel first, well later" construction method, the starting well, the terminal well and other working wells can be set at long distances according to the conditions of the tunnel section, thereby reducing the number of times the shield tunneling machine enters and exits the well, reducing construction risks, alleviating the impact of geological conditions, and ensuring construction safety.

[0065] Based on the first embodiment of the present invention, in the second embodiment of the present invention, the same or similar contents as those in the first embodiment can be referred to the above introduction and will not be described in detail later. Figure 2 At A in step S10, step S11 to S12 are also included:

[0066] Step S11, using a shield tunneling machine to perform shield tunneling construction on the tunnel section;

[0067] Step S12: During the shield tunneling process, a shield tunneling machine is used to lay tunnel segments on the inner wall of the tunnel section.

[0068] It should be noted that during the tunnel segment laying process, the shield tunneling machine uses its own segment assembly machine to precisely position and join the tunnel segments, first installing the radial segments, then the wedge segments, and finally the capping segments to form a complete tunnel segment ring. The segments are connected by bolts to ensure structural stability; rubber seals can also be installed at the joints of the tunnel segments to prevent groundwater infiltration.

[0069] In the second embodiment of the present invention, a shield tunneling machine is used to perform shield construction to form a tunnel section, thereby ensuring the efficiency of shield construction; tunnel segments are laid on the inner wall of the tunnel section while the shield is excavating. This synchronous laying method not only improves the efficiency of tunnel construction, reduces waiting time, and speeds up the construction progress, but also allows the synchronously laid segments to provide immediate structural support for the tunnel section when the shield tunneling machine advances forward, effectively preventing the collapse of the soil around the tunnel and ensuring the stability and safety of the tunnel.

[0070] Based on the first embodiment of the present invention, in the third embodiment of the present invention, the same or similar contents as those in the first embodiment can be referred to the above introduction and will not be described in detail. Figure 2 At B in step S20, step S21-S22 are also included:

[0071] Step S21: using the portion of the tunnel section where the working pit is to be constructed as a specific section, using multiple steel templates to respectively block both ends of the specific section, and using the steel templates to provide support for the tunnel;

[0072] Please note that Figure 3 , multiple steel formworks are erected at both ends of a specific section and sealed. When the steel formwork provides support for the tunnel, it needs to withstand the full head water and soil pressure from the ground to the tunnel section.

[0073] Step S22: using a grouting steel pipe passing through the steel formwork to pour a filling body into the interior of the steel formwork.

[0074] In step S22, the filling body poured into the interior of the steel formwork can not only play a certain reinforcing role, but also can achieve the purpose of blocking sand and gravel, thereby meeting the requirement of preventing sand leakage.

[0075] Furthermore, to prevent groundwater from seeping into the tunnel sub-sections, in one feasible implementation, the filler can be constructed of lightweight foamed concrete. This material, with its low permeability and sufficient strength, meets the requirements for waterproofing and sand control, preventing groundwater from seeping into the tunnel sub-sections and protecting the stability and safety of the tunnel during interlocking pile construction.

[0076] In addition, in order to solve the problem that the coverage of the filling body of the grouting steel pipe is limited, resulting in the filling body being unable to fully fill the interior of the steel formwork, in a feasible implementation method, please refer to Figure 2 A in the Figure 3 Each of the steel templates is provided with at least two grouting steel pipes, and the vertical spacing between two adjacent grouting steel pipes is in the range of 0.9 to 1.1 m.

[0077] In this embodiment, after testing, the filling body poured by each grouting steel pipe can cover a range of approximately 1.5m to 2.0m in radius. Therefore, the vertical spacing between two adjacent grouting steel pipes is set to 0.9 to 1.1m, which can enable the filling body to fully fill the interior of the steel formwork, thereby allowing the filling body to fully play its supporting role and the role of blocking sand and gravel.

[0078] In the third embodiment of the present invention, through the erection and sealing of the steel formwork, the steel formwork can provide support for the tunnel section, the steel formwork and the filling body poured inside it can withstand the full head water and soil pressure calculated from the ground, and the filling body poured inside the steel formwork can also meet the requirements of preventing sand leakage, thereby achieving reinforcement effect and sand leakage prevention effect.

[0079] Based on the first embodiment of the present invention, in the fourth embodiment of the present invention, the same or similar contents as those in the first embodiment can be referred to the above introduction and will not be described in detail. Figure 2 At C in step S30, step S31 to S34 are also included:

[0080] Step S31, removing the tunnel segments on the inner walls of the tunnel sub-intervals within the annular area in blocks;

[0081] It should be noted that the block-by-block dismantling of the tunnel segments can be achieved by chiseling out the joints of the tunnel segments and using mechanical arms, lifting equipment and other equipment to separate and remove the tunnel segments from the inner wall of the tunnel section.

[0082] Step S32: constructing hard bite piles along the vertical direction at both ends of the middle section, and extending the hard bite piles along the vertical direction to the ground to form the support structure;

[0083] It should be noted that hard-bite piles are a type of pile in foundation reinforcement technology, which are mainly used to improve soil bearing capacity and reduce foundation settlement. They can form good mechanical bite with the surrounding soil, thereby enhancing the stability of the entire foundation.

[0084] Step S33, constructing on the inner side of the hard bite pile to form a top beam;

[0085] Among them, see Figure 3 The setting of the top beam can enhance the overall stability of the support structure.

[0086] Step S34, constructing a first double-tube rotary jet pile along the outer ring of the hard bite pile at the top of the hard bite pile and obtaining a second double-tube rotary jet pile along the inner ring of the hard bite pile at the top of the hard bite pile.

[0087] It should be noted that the first and second double-tube jet grouting piles are formed using a high-pressure jet grouting process. This configuration enhances the support capabilities of the hard-interlocking piles, improving the stability and load-bearing capacity of the entire support structure. Furthermore, during the construction of the working pit, the presence of the first and second double-tube jet grouting piles effectively prevents the loss of surrounding soil and sand layers, maintaining their stability.

[0088] Furthermore, before the working shaft is constructed, in order to solve the problem of surface water seeping into the working shaft and soil landslide, as an optional implementation method, after step S34, the shield tunnel construction method further includes steps S35 to S36:

[0089] Step S35, constructing along the annular top of the hard bite pile to form a retaining wall;

[0090] Step S36: constructing along the outer periphery of the first double-tube jet grouting pile to form a water intercepting ditch.

[0091] In this implementation, see Figure 3 The setting of retaining walls can prevent the surface soil from moving toward the working well, preventing the surface soil from sliding into the working well; the setting of intercepting ditches can intercept the infiltration of external water into the working well, keep the inside of the working well dry, and avoid problems such as soil loosening caused by water infiltration.

[0092] Furthermore, in order to solve the problem of how to ensure the bearing strength of the first double-tube rotary jet pile and the second double-tube rotary jet pile, as an optional implementation method, please refer to Figure 3 , the thickness of the first double-tube rotary jet pile is ≥1.5m; and / or, the thickness of the second double-tube rotary jet pile is ≥1.5m; and / or, the hard bite pile is set as a reinforced concrete pile.

[0093] In this embodiment, by setting the thickness of the first double-tube rotary jet pile and the second double-tube rotary jet pile to be greater than or equal to 1.5m, it is ensured that the first double-tube rotary jet pile and the second double-tube rotary jet pile have higher rigidity and bearing capacity, can better resist the lateral pressure of the soil, and improve the stability of the overall structure.

[0094] In the fourth embodiment of the present invention, the tunnel segments on the inner wall of the tunnel subsection are first removed to avoid obstruction to the construction of the support structure. Hard-engraved piles are then constructed to form the main part of the support structure, providing a supporting effect. Finally, capping beams are constructed inside the hard-engraved piles to enhance the overall stability of the support structure. Furthermore, the first and second double-tube jet-jet piles are formed using a high-pressure jet-jet process, which enhances the support capacity of the hard-engraved piles and improves the stability and load-bearing capacity of the entire support structure.

[0095] Based on the first embodiment of the present invention, in the fifth embodiment of the present invention, the same or similar contents as those in the first embodiment can be referred to the above introduction and will not be described in detail later. Figure 2 At D in step S40, step S41 to S43 are also included:

[0096] Step S41: excavating earth in the vertical direction within the area enclosed by the supporting structure, cleaning the base of the earth, and laying a structural base plate on the base;

[0097] Step S42: tying steel bars along the inner wall of the support structure and installing an end wall formwork, and pouring concrete in the end wall formwork to form the main structural end wall of the working pit;

[0098] Step S43, tying steel bars on the top of the end wall of the main structure and installing a top cover formwork, pouring concrete in the top cover formwork to form the top cover of the working pit.

[0099] Furthermore, in order to solve the problems of groundwater influence, chemical corrosion, physical damage and other issues of the structural base, as an optional implementation method, please refer to Figure 3 A fine stone concrete protective layer at the upper layer and a concrete cushion layer at the lower layer are laid under the structural base plate.

[0100] In this embodiment, the fine aggregate concrete protective layer protects the structural base from groundwater, chemical corrosion, and physical damage. However, if the structure near the base is a gravel structure, pouring concrete directly on the gravel base will cause some mortar in the concrete to flow into the base's voids, resulting in defects such as honeycombing in the concrete surface, thus reducing the durability of the fine aggregate concrete protective layer. However, the installation of a concrete cushion layer reduces mortar loss during the pouring of the fine aggregate concrete protective layer, ensuring the quality of the fine aggregate concrete protective layer.

[0101] In the fifth embodiment of the present invention, please refer to Figure 3 First, excavate the earth and lay the structural floor on the base of the earth to ensure the structural strength of the base. Then, by tying steel bars, installing formwork, and pouring concrete, the main structural end wall and top cover of the working pit are obtained respectively, thus completing the construction of the working pit.

[0102] See also Figure 3 The present invention also provides a tunnel structure constructed using the shield tunnel construction method described in the above-mentioned embodiments. The specific implementation of this shield tunnel construction method is similar to the above-mentioned embodiments. Since this tunnel structure utilizes all the technical solutions of all of the above-mentioned embodiments, it possesses at least all the beneficial effects of the technical solutions of the above-mentioned embodiments, and therefore will not be further elaborated here.

[0103] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made by utilizing the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A shield tunnel construction method, characterized in that: The following steps are involved: Conduct shield construction to form tunnel sections; Performing local reinforcement within the tunnel section to form a locally reinforced tunnel subsection; wherein the tunnel subsection includes a middle section and reinforced sections located at both ends of the middle section; Constructing in a vertical direction within the annular area to form an annular support structure; wherein the coverage of the annular area includes the middle section and partially includes the reinforcement section; Conducting construction in a vertical direction within the area enclosed by the support structure to form a working pit; Removing the reinforcement structure in the reinforcement section and removing the structure of the support structure located within the reinforcement section to make the tunnel section transversely connected; The step of locally reinforcing the tunnel section to form a locally reinforced tunnel subsection includes: The portion of the tunnel section where the working pit is to be constructed is used as a specific section, and a plurality of steel templates are used to respectively block both ends of the specific section, and the steel templates are used to provide support for the tunnel; Using a grouting steel pipe passing through the steel formwork to pour a filling body into the interior of the steel formwork; The step of constructing in the vertical direction within the annular area to form an annular support structure includes: removing the tunnel segments on the inner walls of the tunnel sub-intervals within the annular area in blocks; constructing hard bite piles at both ends of the middle section in a vertical direction, and extending the hard bite piles in a vertical direction to the ground to form the support structure; constructing on the inner side of the hard bite pile to form a top beam; A first double-tube rotary jet pile is constructed along the outer ring of the hard bite pile at the top of the hard bite pile, and a second double-tube rotary jet pile is constructed along the inner ring of the hard bite pile at the top of the hard bite pile.

2. The shield tunnel construction method according to claim 1, wherein: The steps of performing shield construction to form a tunnel section include: Performing shield tunneling construction on the tunnel section using a shield tunneling machine; During the shield tunneling process, a shield tunneling machine is used to lay tunnel segments on the inner wall of the tunnel section.

3. The shield tunnel construction method according to claim 1, wherein: The filler is a lightweight foam concrete material; And / or, each of the steel formworks is provided with at least two grouting steel pipes, and the vertical spacing between two adjacent grouting steel pipes is in the range of 0.9 to 1.1 m.

4. The shield tunnel construction method according to claim 1, wherein: After the steps of constructing a first double-tube rotary grouting pile along the outer ring of the hard bite pile at the top of the hard bite pile and constructing a second double-tube rotary grouting pile along the inner ring of the hard bite pile at the top of the hard bite pile, the method further comprises: constructing along the annular top of the hard bite pile to form a retaining wall; Construction is carried out along the outer periphery of the first double-tube jet grouting pile to form a water intercepting ditch.

5. The shield tunnel construction method according to claim 1, wherein: The thickness of the first double-tube jet grouting pile is ≥1.5m; And / or, the thickness of the second double-tube jet grouting pile is ≥1.5m; And / or, the hard bite piles are configured as reinforced concrete piles.

6. The shield tunnel construction method according to claim 1, wherein: The step of constructing in the vertical direction within the area enclosed by the support structure to form a working pit includes: excavating earth in a vertical direction within the area enclosed by the supporting structure, cleaning the base of the earth, and laying a structural base plate on the base; Tie steel bars along the inner wall of the support structure and install end wall formwork, and pour concrete in the end wall formwork to form the main structural end wall of the working pit; Reinforcement is tied to the top of the end wall of the main structure and a top cover formwork is installed, and concrete is poured into the top cover formwork to form the top cover of the working pit.

7. The shield tunnel construction method according to claim 6, characterized in that: A fine stone concrete protective layer at the upper layer and a concrete cushion layer at the lower layer are laid below the structural bottom plate.

8. A tunnel structure, characterized in that: The shield tunnel is constructed using the shield tunnel construction method according to any one of claims 1 to 7.

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