Shield tunnel construction method and tunnel structure

Abstract

The invention discloses a shield tunnel construction method and a tunnel structure, and relates to the technical field of tunnel construction.The shield tunnel construction method comprises the following steps that shield construction is conducted to form a tunnel section; locally reinforcing the interior of the tunnel section to form locally reinforced tunnel subsections; each tunnel subinterval comprises a middle section and reinforcing sections located at the two ends of the middle section. Construction is conducted in the annular area in the vertical direction, so that an annular supporting structure is formed; the coverage area of the annular area comprises a middle section and partially comprises a reinforcing section; construction is conducted in the area defined by the supporting structure in the vertical direction, so that a working well is formed; and the reinforcing structure in the reinforcing section is dismantled, and the structure, located in the reinforcing section, in the supporting structure is dismantled, so that the tunnel section is transversely through. According to the construction method, the tunnel is obtained through first construction, and then the working well is formed through second construction, so that the influence caused by external environments such as land acquisition and demolition and pipeline relocation is remarkably reduced, and the construction delay risk is effectively reduced.

Description

Technical Field

[0001] The 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] The electric shield tunnel is an important part of the city's underground power facilities. Its construction process involves complex geological conditions, strict construction accuracy and safety requirements. At present, in the construction of shield tunnels, under the condition of meeting the construction technical requirements, in order to improve the economic efficiency of the project, the shield starting and ending shafts can be set at a distance greater than 2km. However, according to the needs of the layout of the power tunnel maintenance equipment and the requirements of fire escape, the power working shaft is generally set at a distance of 400m to 600m. Generally, the power working shaft also serves as the shield starting and ending shaft.

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

[0004] However, power tunnels are generally built in urban core areas or renewal areas. Along the tunnel route, there are often a large number of relocation and compensation issues for residents, enterprises and institutions in the construction area. These issues require a lot of time to complete complex coordination work. If the progress of land acquisition and demolition is seriously delayed, the construction of the power shaft will not be carried out as planned, which will affect the overall construction progress of the power tunnel. In addition, due to the complexity of urban underground pipelines, including electricity, communications, gas, water supply and drainage, etc., the relocation of these pipelines requires coordination with many units, which increases the difficulty and uncertainty of construction. According to engineering experience, according to the traditional "well first and tunnel later" construction method, these complex external conditions often lead to the construction of the working shaft cannot be carried out as planned, which in turn leads to the delay of the shield construction progress of the subsequent tunnel section, which has a great impact on the construction period, while increasing the project cost and producing 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 adopts the "well first and tunnel later" method, which 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 by the present invention comprises the following steps:

[0007] Conduct shield construction to form tunnel sections;

[0008] Performing local reinforcement in 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 the 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] Carrying out construction in the vertical direction within the area enclosed by the supporting structure to form a working pit;

[0011] The reinforcement structure in the reinforcement section is removed, and the structure in the support structure located in 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] Using a shield tunneling machine to perform shield tunneling construction on the tunnel section;

[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 needs to be constructed is taken as a specific section, a plurality of steel templates are used to respectively block the two 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 penetrating 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 ranges from 0.9 to 1.1 m.

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

[0020] Removing the tunnel segments on the inner walls of the tunnel sub-sections located in the annular area in blocks;

[0021] 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;

[0022] constructing on the inner side of the hard bite pile to form a capping 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 along the outer ring of the hard bite pile at the top of the hard bite pile to obtain a first double-tube rotary grouting pile and constructing along the inner ring of the hard bite pile at the top of the hard bite pile to obtain a second double-tube rotary grouting pile, the method further includes:

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

[0026] Construction is performed 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 the vertical direction within the area surrounded by the support structure to form a working pit includes:

[0031] Excavating earth in the area surrounded by the supporting structure in the vertical direction, 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 an 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 in the top cover formwork to form a top cover of the working pit.

[0034] In one embodiment, a fine stone concrete protective layer at an upper layer and a concrete cushion layer at a 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 performed to form a tunnel section; local reinforcement is performed 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 performed in a vertical direction in an 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; construction is performed in a vertical direction in an area surrounded by the support structure to form a working shaft; the reinforcement structure in the reinforcement section is removed, and the structure in the support structure located in the reinforcement section is removed to make the tunnel section horizontally connected.

[0037] The technical solution of the present invention adopts a construction method of "tunnel first, then shaft", that is, a construction method of first constructing a tunnel and then constructing a working shaft. In the construction of urban power shield tunnels, the construction method of "tunnel first, then shaft" can construct the tunnel section before constructing the working shaft, thereby avoiding the problem of delaying the construction progress of the working shaft due to external environments such as land acquisition and demolition, pipeline relocation, etc. in the traditional "shaft first, then tunnel" 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.

[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 limits the utilization efficiency of the shield machine to a certain extent; 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 distance between different working wells before constructing the tunnel section, which may result in a shorter distance between the working wells and a shield tunneling machine needing to enter and exit the well more frequently during the shield construction process. However, after 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 drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 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 a construction process of an embodiment of a shield tunnel construction method provided by the present invention;

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

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

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are 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 in a certain specific posture. If the specific posture changes, the directional indication 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 used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the 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 contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0048] The electric shield tunnel is an important part of the city's underground power facilities. Its construction process involves complex geological conditions, strict construction accuracy and safety requirements. At present, in the construction of shield tunnels, under the condition of meeting the construction technical requirements, in order to improve the economic efficiency of the project, the shield starting and ending shafts can be set at a distance greater than 2km. However, according to the needs of the layout of the power tunnel maintenance equipment and the requirements of fire escape, the power working shaft is generally set at a distance of 400m to 600m. Generally, the power working shaft also serves as the shield starting and ending shaft.

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

[0050] However, power tunnels are generally built in urban core areas or renewal areas. Along the tunnel route, there are often a large number of relocation and compensation issues for residents, enterprises and institutions in the construction area. These issues require a lot of time to complete complex coordination work. If the progress of land acquisition and demolition is seriously delayed, the construction of the power shaft will not be carried out as planned, which will affect the overall construction progress of the power tunnel. In addition, due to the complexity of urban underground pipelines, including electricity, communications, gas, water supply and drainage, etc., the relocation of these pipelines requires coordination with many units, which increases the difficulty and uncertainty of construction. According to engineering experience, according to the traditional "well first and tunnel later" construction method, these complex external conditions often lead to the construction of the working shaft cannot be carried out as planned, which in turn leads to the delay of the shield construction progress of the subsequent tunnel section, which has a great impact on the construction period, while increasing the project cost and producing 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, performing shield construction to form a tunnel section;

[0054] Step S20, locally reinforcing 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 many optional implementation methods for local reinforcement of tunnel sections. For example, anchor rod reinforcement can be adopted, by drilling holes in the inner wall of the tunnel section and implanting anchor rods, and then grouting and fixing; soil nail wall reinforcement can also be adopted, and steel arch reinforcement can also be adopted, etc. The specific local reinforcement method can be selected according to actual needs and is not limited here.

[0056] Step S30, constructing in the annular area along the vertical direction 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 the vertical direction within the area surrounded by the support structure to form a working well;

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

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

[0061] It should be noted that the supporting structure has a part of the structure located inside the reinforcement section and another part of the structure located outside the reinforcement section. In order to allow the tunnel section to be horizontally connected, the part of the supporting structure located inside the reinforcement section needs to be demolished, while the other part of the supporting 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, then shaft" construction method, that is, first constructing the tunnel and then constructing the working shaft, in the construction of urban power shield tunnels, the "tunnel first, then shaft" construction method can construct the tunnel section before constructing the working shaft, thereby avoiding the problem of delaying the construction progress of the working shaft due to external environments such as land acquisition and demolition, pipeline relocation, etc. in the traditional "shaft first, then tunnel" 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 limits the utilization efficiency of the shield machine to a certain extent; 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 distance between different working wells before constructing the tunnel section, which may result in a shorter distance between the working wells and a shield tunneling machine needing to enter and exit the well more frequently during the shield construction process. However, after 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 the step S10, step S11-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, using a shield tunneling machine to lay tunnel segments on the inner wall of the tunnel section.

[0068] It should be noted that during the laying of tunnel segments, the shield tunneling machine uses its own segment assembly machine to accurately position the tunnel segments and splice 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 connections between the tunnel segments can be bolted to ensure the stability of the structure; rubber sealing rings 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 enables the synchronously laid segments to provide immediate structural support for the tunnel section when the shield tunneling machine is excavating 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 later. Figure 2 At B in the step S20, the step S21-S22 is further comprised of:

[0071] Step S21, taking the portion of the tunnel section where the working pit needs to be constructed as a specific section, using a plurality of steel templates to respectively block the two 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 formworks provide support for the tunnel, they need to withstand the full head water and soil pressure from the ground to the tunnel section.

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

[0074] In step S22, the filling body poured inside the steel formwork can not only play a certain reinforcement role, but also can block the sand and gravel to meet the requirement of preventing sand leakage.

[0075] Furthermore, in order to prevent groundwater from seeping into the tunnel sub-intervals, in a feasible implementation, the filler can be set as a lightweight foam concrete material. In this way, by using a lightweight foam concrete material as the filler, it has low permeability and a certain strength, can meet the requirements of waterproofing and sand prevention, prevent groundwater from seeping into the tunnel sub-intervals, and protect the stability and safety of the formed tunnel during the construction of the bite pile.

[0076] In addition, in order to solve the problem that the coverage of the filling body poured into 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, refer to Figure 2 A in 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 the reinforcement effect and the effect of preventing sand leakage.

[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 refer to the above introduction, and will not be repeated in the following. Figure 2 At C in step S30, step S31 to S34 are also included:

[0080] Step S31, removing the tunnel segments on the inner wall of the tunnel sub-intervals located in 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 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;

[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 a 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 along the outer ring of the hard bite pile at the top of the hard bite pile to obtain a first double-tube rotary jet pile, and constructing along the inner ring of the hard bite pile at the top of the hard bite pile to obtain a second double-tube rotary jet pile.

[0087] It should be noted that the first double-tube jet grouting pile and the second double-tube jet grouting pile are formed by a high-pressure jet grouting process, and their arrangement can enhance the support capacity of the hard-bite pile and improve the stability and bearing capacity of the entire support structure. In addition, during the construction of the working well, the presence of the first double-tube jet grouting pile and the second double-tube jet grouting pile can effectively prevent the loss of the surrounding soil and sand layers and maintain the stability of the surrounding soil and sand layers.

[0088] Furthermore, before the working shaft is constructed, in order to solve the problem of ground water infiltration into the working shaft and soil landslide, as an optional implementation, 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 circumference 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 block the movement of surface soil to the working well and prevent 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] Further, in order to solve the problem of how to ensure the bearing strength of the first double-tube jet grouting pile and the second double-tube jet grouting 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 sub-interval are first removed to avoid obstruction to the construction of the support structure, and then the hard bite piles are constructed to form the main part of the support structure to provide a support effect, and finally the top beams are constructed on the inner side of the hard bite piles to enhance the overall stability of the support structure. In addition, the first double-tube jet grouting pile and the second double-tube jet grouting pile are formed by a high-pressure jet grouting process, which can enhance the support capacity of the hard bite piles and improve the stability and 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 area surrounded by the supporting structure in the vertical direction, 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 an end wall of the main structure 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, and pouring concrete in the top cover formwork to form a top cover of the working pit.

[0099] Furthermore, in order to solve the problems of groundwater influence, chemical corrosion, physical damage and other problems of the structural bottom plate, 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 bottom plate.

[0100] In this embodiment, the fine stone concrete protective layer can protect the structural bottom plate from groundwater, chemical corrosion and physical damage. However, when the structure near the base is a sandstone structure, pouring concrete directly on the base of the sandstone structure will cause the mortar in the concrete to partially flow into the gaps of the base, resulting in defects such as honeycombs on the concrete surface, thereby reducing the durability of the fine stone concrete protective layer; after setting the concrete cushion layer, the mortar loss during the pouring of the fine stone concrete protective layer can be reduced, ensuring the quality of the fine stone concrete protective layer.

[0101] In the fifth embodiment of the present invention, please refer to Figure 3 , by first excavating the earth and laying the structural floor on the base of the earth to ensure the structural strength of the base, and then by tying steel bars, installing formwork, and pouring concrete to obtain the main structural end wall and top cover of the working pit, thus completing the construction of the working pit.

[0102] See also Figure 3 The present invention also proposes a tunnel structure, which is constructed by the shield tunnel construction method in the above embodiment. The specific implementation method of the shield tunnel construction method refers to the above embodiment. Since the present tunnel structure adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0103] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are 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 in 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 the 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; Carrying out construction in the vertical direction within the area enclosed by the supporting structure to form a working pit; The reinforcement structure in the reinforcement section is removed, and the structure in the support structure located in the reinforcement section is removed to make the tunnel section transversely connected.

2. The shield tunnel construction method according to claim 1, characterized in that: The steps of performing shield construction to form a tunnel section include: Using a shield tunneling machine to perform shield tunneling construction on the tunnel section; 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, characterized in that: The step of locally reinforcing the tunnel section to form a locally reinforced tunnel subsection comprises: The portion of the tunnel section where the working pit needs to be constructed is taken as a specific section, a plurality of steel templates are used to respectively block the two ends of the specific section, and the steel templates are used to provide support for the tunnel; The filling body is poured into the interior of the steel formwork by using a grouting steel pipe penetrating the steel formwork.

4. The shield tunnel construction method according to claim 3, characterized in that: 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.

5. The shield tunnel construction method according to claim 1, characterized in that: The steps of constructing in the annular area along the vertical direction to form an annular support structure include: Removing the tunnel segments on the inner walls of the tunnel sub-sections located in the annular area in blocks; 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; constructing on the inner side of the hard bite pile to form a capping 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.

6. The shield tunnel construction method according to claim 5, characterized in that: After the steps of constructing along the outer ring of the hard bite pile at the top of the hard bite pile to obtain the first double-tube rotary jet pile, and constructing along the inner ring of the hard bite pile at the top of the hard bite pile to obtain the second double-tube rotary jet pile, the method further includes: constructing along the annular top of the hard bite pile to form a retaining wall; Construction is performed along the outer periphery of the first double-tube jet grouting pile to form a water intercepting ditch.

7. The shield tunnel construction method according to claim 5, characterized in that: 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.

8. The shield tunnel construction method according to claim 1, characterized in that: The step of constructing in the vertical direction within the area surrounded by the support structure to form a working well comprises: Excavating earth in the area surrounded by the supporting structure in the vertical direction, 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 an 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 in the top cover formwork to form a top cover of the working pit.

9. The shield tunnel construction method according to claim 8, 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.

10. A tunnel structure, characterized in that: The shield tunnel is constructed using the shield tunnel construction method described in any one of claims 1 to 9.

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