A method for close proximity shield tunnel and foundation pit intersection construction

Abstract

The application provides a close shield tunnel and foundation pit intersection construction method, and relates to the technical field of municipal engineering construction. The method comprises the following steps: setting a supporting wall on both sides of a target foundation pit area and between two shield tunnel areas; then excavating the target foundation pit area to an initial design depth to form an initial foundation pit; setting a second supporting mechanism for resisting the supporting wall in the initial foundation pit, and then performing shield tunnel crossing construction on one side of the shield tunnel area; after the shield tunnel construction on the side is completed, setting a supporting structure in the shield tunnel; then excavating the initial foundation pit to a target design depth to form a target foundation pit and setting a third supporting mechanism for resisting the supporting wall; the length of the second supporting mechanism and the third supporting mechanism in the direction between the supporting walls is adjustable; and performing shield tunnel crossing construction on the remaining side of the shield tunnel area. The construction efficiency can be improved and the construction period can be optimized under the premise of ensuring construction safety and reliability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of municipal engineering construction, in particular to a method for cross construction of a shield tunnel and a foundation pit in close proximity. BACKGROUND

[0002] In a city subway, the access (section) line interval is like a channel connecting the station and the subway vehicle "parking lot" (that is, the vehicle depot). This channel and the subway main line interval (that is, the normal operation line of the subway) will inevitably cross, either on the same plane (crossing), or on different heights (overpassing), and this place where the crossing occurs is usually called the superimposed intersection area.

[0003] At present, in order to reduce the difficulty of construction, an independent scheme is usually adopted. That is, one of the lines (such as the main line interval) is first completely constructed, and then the other line (the access (line interval) is constructed. However, when the latter line is under construction, some engineering measures need to be taken to protect the first completed line because it will be affected by the latter line. For example, isolation piles or trestle systems are built to play a buffering and isolating role.

[0004] With the continuous development of the city, there are more and more subway lines, and the construction land becomes very scarce. If the traditional independent scheme is still used, the construction process will become very complicated, and many steps and links need to be coordinated, which is very difficult. Moreover, the construction process is complex, the construction period is long, and the cost is also high. Finally, the superimposed intersection area often becomes the "neck" section of the entire subway line opening, which affects the timely opening of the entire subway line.

[0005] Therefore, it is necessary to design a construction method to enable the access line and the main line of the superimposed intersection area to be constructed at the same time, that is, the shield tunnel and the foundation pit are constructed at the same time. This synchronous cross construction can not only meet the safety requirements of design and construction, but also optimize the construction period and process, make the construction more efficient, save engineering cost, and better meet the needs of urban development. SUMMARY

[0006] The present application provides a method for cross construction of a shield tunnel and a foundation pit in close proximity, which can solve the problems of long construction period, complicated construction process and high cost caused by the conventional construction method in the construction of a shield tunnel and a foundation pit in close proximity.

[0007] The present application provides a method for cross construction of a shield tunnel and a foundation pit in close proximity, which can solve the problems of long construction period, complicated construction process and high cost caused by the conventional construction method in the construction of a shield tunnel and a foundation pit in close proximity.

[0008] A support wall is arranged on both sides of the target foundation pit area and between the two shield tunnel areas; then the target foundation pit area is excavated to an initial design depth to form an initial foundation pit; the top of the support wall is lower than the ground level and higher than the bottom of the initial foundation pit, and the bottom of the support wall is lower than the bottom of the shield tunnel area;

[0009] A second support mechanism for resisting the support wall is arranged in the initial foundation pit, and then shield tunnel construction is performed on one side of the shield tunnel area; after the shield tunnel construction on this side is completed, a support structure is arranged in the shield tunnel; then the initial foundation pit is excavated to a target design depth to form a target foundation pit and a third support mechanism for resisting the support wall is arranged; the length of the second support mechanism and the third support mechanism in the direction between the support walls is adjustable;

[0010] Shield tunnel construction is performed on the remaining side of the shield tunnel area.

[0011] In some embodiments, after the initial foundation pit is formed, before the second support mechanism for resisting the support wall is arranged in the initial foundation pit, cement is mixed into the soil body by using a mixing pile to form a reinforced reinforced soil body, and the cement is mixed below the target design depth of the target foundation pit.

[0012] In some embodiments, after the target foundation pit is formed and the third support mechanism for resisting the support wall is arranged, before the shield tunnel construction is performed on the remaining side of the shield tunnel area, the second support mechanism and the third support mechanism are removed, the main structure is constructed in the target foundation pit, and the soil body is backfilled on the top of the main structure.

[0013] In some embodiments, in the vertical direction, the bottom of the main structure is located at the same height as the target design depth of the target foundation pit.

[0014] In some embodiments, when the support structure is arranged in the shield tunnel, a plurality of shield segments are connected closely along the tunnel axis by a tensioning device, and a plurality of steel frames for temporary support are arranged on the inner wall of the shield segment.

[0015] In some embodiments, a servo system is further included, which includes a numerical control pump station, a support head, and a main machine driving the support head to extend and retract, the support head being connected to the second support mechanism and the third support mechanism to drive the second support mechanism or the third support mechanism to extend or retract in the direction of the support wall.

[0016] In some embodiments, when the second support mechanism and the third support mechanism for resisting the support wall are arranged, a monitoring system is used to monitor the deformation information of the shield tunnel, the target foundation pit, and the soil body around the shield tunnel, and the information is transmitted to the servo system.

[0017] In some embodiments, when it is monitored that the soil around the shield tunnel moves towards the direction where the supporting wall is located, the servo system controls the second supporting mechanism and the third supporting mechanism to extend towards the direction where the supporting wall is located to resist the supporting wall; when it is monitored that the soil around the shield tunnel does not move towards the direction where the supporting wall is located, the servo system controls the second supporting mechanism and the third supporting mechanism to retract to or remain in the normal working state.

[0018] In some embodiments, when the supporting walls are arranged on both sides of the target foundation pit, grooves are first designed at the positions on both sides of the target foundation pit, and then concrete is poured to form the supporting walls.

[0019] In some embodiments, when the target foundation pit area is excavated to an initial design depth to form an initial foundation pit, two crown beams are arranged on the top of the two supporting walls in the length direction respectively, the first supporting mechanism is arranged between the two crown beams, and a retaining wall with a top higher than the ground is arranged on the crown beam.

[0020] The technical scheme provided by the embodiments of the present application has the following beneficial effects:

[0021] The embodiments of the present application provide a method for cross construction of a shield tunnel and a foundation pit, comprising:

[0022] Supporting walls are arranged on both sides of the target foundation pit area and between the two shield tunnel areas; then the target foundation pit area is excavated to an initial design depth to form an initial foundation pit; the top of the supporting wall is lower than the ground and higher than the bottom height of the initial foundation pit, and the bottom of the supporting wall is lower than the bottom height of the shield tunnel area;

[0023] A second supporting mechanism for resisting the supporting wall is arranged in the initial foundation pit, and then shield tunnel crossing construction is performed on one side of the shield tunnel area; after the construction of the shield tunnel on this side is completed, a supporting structure is arranged in the shield tunnel; then the initial foundation pit is excavated to a target design depth to form a target foundation pit and a third supporting mechanism for resisting the supporting wall is arranged; the length of the second supporting mechanism and the third supporting mechanism in the direction between the supporting walls is adjustable;

[0024] Shield tunnel crossing construction is performed on the remaining side of the shield tunnel area.

[0025] The present application breaks the traditional independent construction scheme, realizes the cross construction of the shield tunnel and the foundation pit, avoids the complicated process of completing one line and then constructing another line in the traditional scheme, for example, constructing the shield tunnel first and then constructing the foundation pit after the construction is completed, omits the step of arranging isolation piles and trestle systems in the conventional construction, reduces the coordination difficulty between steps and links, and can optimize the construction period and improve the construction efficiency on the premise of ensuring construction safety and reliability.

[0026] The supporting wall separates the target foundation pit area from the shield tunnel areas on both sides, prevents the deformation of the soil from affecting the shield tunnel areas during the subsequent foundation pit excavation, protects the safety and stability of the shield tunnel structure, provides a resisting point for the second supporting mechanism and the third supporting mechanism, enables the supporting mechanisms to effectively play a role, and enhances the stability of the foundation pit. The bottom of the supporting wall is lower than the bottom of the shield tunnel area, and it can effectively support and stabilize the soil above the tunnel. In practice, the initial foundation pit is excavated first, and the second supporting mechanism cooperates with the supporting wall to enhance the stability of the soil on the side wall of the foundation pit through the resisting effect of the second supporting mechanism, prevent excessive deformation of the side wall of the foundation pit before the shield tunnel passes through, ensure the safety of construction, and provide a stable surrounding environment for subsequent shield tunnel construction. Then, the cross construction method is used to pass through the construction of one side of the shield tunnel, and the foundation pit is not constructed at this time. After the construction of the shield tunnel on this side is completed, the supporting structure can enhance the stability of the tunnel structure, prevent deformation or damage of the tunnel due to changes in soil stress during the subsequent excavation of the foundation pit. Then, the foundation pit is excavated to the target design depth to meet the use requirements of the foundation pit and provide a foundation for the construction of subsequent related facilities. During the excavation of the foundation pit, the soil stress changes constantly, and part of the foundation pit is curved. At this time, the second supporting mechanism and the plurality of third supporting mechanisms with adjustable lengths can flexibly adjust the supporting strength and range according to the actual situation of different construction stages, better adapt to the deformation of the soil, and ensure the stability of the foundation pit and the surrounding soil. Then, the shield tunnel passing construction is performed on the remaining side of the shield tunnel area.

[0027] Specifically, when the surrounding soil activity is monitored, the length of the second supporting mechanism and the third supporting mechanism in the direction between the supporting walls can be adjusted according to the direction and degree of the soil activity. If the soil has a tendency to move and deform into the foundation pit, the length of the supporting mechanism is appropriately increased to enhance the resisting force of the supporting wall, prevent the deformation of the soil, and ensure the stability of the side wall of the foundation pit. If the soil activity changes, the length of the supporting mechanism can also be adjusted accordingly to adapt to the new soil stress state. If the soil activity affects the shield tunnel, the supporting structure in the shield tunnel can resist the force caused by the change in soil stress through its strength and rigidity to prevent deformation or damage of the tunnel structure. At the same time, the supporting structure can be reinforced or its arrangement mode can be adjusted according to the actual situation to ensure the safety and stability of the shield tunnel under the soil activity. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating any inventive labor.

[0029] Figure 1 a cross-sectional view of the structure in the preliminary construction state provided by the embodiment of the present application;

[0030] Figure 2 a cross-sectional view of the structure in the preliminary construction state provided by the embodiment of the present application; Figure 1 a cross-sectional view of the structure in the preliminary construction state provided by the embodiment of the present application;

[0031] Figure 3 a cross-sectional view of the structure in the preliminary construction state provided by the embodiment of the present application;

[0032] Figure 4 a cross-sectional view of the structure in the preliminary construction state provided by the embodiment of the present application;

[0033] Figure 5 a cross-sectional view of the structure in the preliminary construction state provided by the embodiment of the present application;

[0034] Figure 6 a cross-sectional view of the structure in the preliminary construction state provided by the embodiment of the present application;

[0035] In the drawings:

[0036] 1, initial foundation pit; 2, shield tunnel; 3, support wall; 4, second support mechanism; 5, third support mechanism; 6, first support mechanism; 7, support structure; 8, main structure; 10, reinforced soil; 11, target foundation pit; 21, shield segment; 91, crown beam; 92, retaining wall. DETAILED DESCRIPTION

[0037] In order to enable persons skilled in the art to better understand the scheme of the present application, the technical scheme in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by persons skilled in the art without creative labor fall within the scope of protection of the present application.

[0038] The embodiment of the present application provides a cross construction method of a shield tunnel and a foundation pit in close proximity, which can solve the problems of long construction period, complicated construction procedure and high cost caused by conventional construction methods in the construction of a shield tunnel and a foundation pit in close proximity in the prior art.

[0039] Referring to FIG. 1, Figures 1 to 3 , Figure 6 The embodiment of the present application provides a cross construction method of a shield tunnel and a foundation pit in close proximity, which includes:

[0040] S1. Set up retaining walls 3 on both sides of the target pit 11 area and between the two shield tunnel 2 areas; then excavate the target pit 11 area to the initial design depth to form the initial pit 1; the top height of the retaining wall 3 is lower than the ground and higher than the bottom height of the initial pit 1, and the bottom height of the retaining wall 3 is lower than the bottom height of the shield tunnel 2 area.

[0041] S2. A second support mechanism 4 is installed in the initial foundation pit 1 to support the retaining wall 3, and then the shield tunnel 2 is constructed to pass through one side of the shield tunnel 2 area; after the shield tunnel 2 on that side is completed, a support structure 7 is installed in the shield tunnel 2; then the initial foundation pit 1 is excavated to the target design depth to form the target foundation pit 11 and a third support mechanism 5 is installed to support the retaining wall 3; the lengths of the second support mechanism 4 and the third support mechanism 5 in the direction between the retaining wall 3 are adjustable;

[0042] S3. Conduct shield tunnel 2 crossing construction on the remaining side of shield tunnel 2 area.

[0043] This application breaks with the traditional independent construction scheme, realizing the cross-construction of shield tunnel 2 and target pit 11. It avoids the cumbersome process of constructing one line after another in the traditional scheme. For example, shield tunnel 2 is constructed first, and target pit 11 is constructed after the construction is completed. It omits the steps of setting up isolation piles and trestle bridge systems in conventional construction, reduces the coordination difficulty between various steps and links, and optimizes the construction period and improves construction efficiency while ensuring construction safety and reliability.

[0044] The retaining wall 3 separates the target pit 11 area from the shield tunnel 2 areas on both sides, preventing soil deformation from affecting the shield tunnel 2 area during the subsequent excavation of the target pit 11. This protects the structural safety and stability of the shield tunnel 2 and provides a support point for the subsequent second and third support mechanisms 4 and 5, enabling the support mechanisms to function effectively and enhancing the stability of the target pit 11. The bottom height of the retaining wall 3 is lower than the bottom height of the shield tunnel 2 area, providing effective support and stability to the soil above the tunnel. In practice, the initial pit 1 is excavated first, and the second support mechanism 4 works in conjunction with the retaining wall 3. The support effect of the second support mechanism 4 enhances the soil stability of the target pit 11 sidewalls, preventing excessive deformation of the target pit 11 sidewalls before the shield tunnel 2 passes through, ensuring construction safety, and providing a stable surrounding environment for the subsequent construction of the shield tunnel 2. Then, a cross-construction method was adopted. First, the shield tunnel 2 on one side was constructed, while construction at the target pit 11 was not carried out. After the shield tunnel 2 on this side was completed, a support structure 7 was installed to enhance the stability of the tunnel structure and prevent deformation or damage to the tunnel due to changes in soil stress during the subsequent excavation of the target pit 11. Then, the target pit 11 was excavated to the target design depth to meet the usage requirements of the target pit 11 and provide a foundation for the construction of subsequent related facilities. During the excavation of the target pit 11, the soil stress continuously changed, and part of the pit was curved. At this time, the adjustable-length second support mechanism 4 and multiple third support mechanisms 5 could flexibly adjust the support strength and range according to the actual situation at different construction stages, better adapting to soil deformation and ensuring the stability of the target pit 11 and the surrounding soil. Then, the shield tunnel 2 on the remaining side was constructed.

[0045] Specifically, when soil movement is detected, the lengths of the second and third support structures 4 and 5 between the retaining wall 3 can be adjusted according to the direction and extent of the soil movement. If the soil tends to move and deform into the target pit 11, the length of the support structure can be appropriately increased to enhance the bearing capacity of the retaining wall 3, prevent soil deformation, and ensure the stability of the sidewall of the target pit 11. If the soil movement changes, the length of the support structure can also be adjusted accordingly to adapt to the new soil stress state. If soil movement affects the shield tunnel 2, the support structure 7 inside the shield tunnel 2 can resist the forces caused by changes in soil stress through its own strength and stiffness, preventing deformation or damage to the tunnel structure. At the same time, the support structure 7 can be reinforced or its arrangement adjusted according to the actual situation to ensure the safety and stability of the shield tunnel 2 under soil movement conditions.

[0046] This application is applicable to construction environments where the central section is a foundation pit and the two sides are adjacent shield tunnels. By setting up retaining walls 3 and adjustable support mechanisms, combined with staged shield tunnel crossing construction, the cross-construction of the adjacent shield tunnel 2 and the target foundation pit 11 was achieved. While ensuring construction safety, the construction process was optimized, construction efficiency was improved, construction costs were reduced, and many problems associated with traditional independent construction schemes were avoided.

[0047] In actual construction, conventional methods often require additional facilities such as bollards and trestle systems, placing significant demands on the size and layout of the construction site. Larger construction sites not only increase rental costs but also present more coordination challenges due to the complex surrounding environment, such as land acquisition, demolition, and traffic management. This construction method eliminates the need for bollards, minimizing the required site area and maximizing the use of limited space. This advantage is particularly pronounced in urban subway construction where space is limited, effectively reducing the impact on the surrounding environment and traffic, and lowering coordination difficulties and costs during construction.

[0048] Furthermore, the technical solution of this application omits the installation of isolation piles and other related structures, reducing costs associated with the procurement of materials and rental of construction equipment for isolation piles. It also reduces site rental fees and related expenses incurred due to site coordination. Moreover, by shortening the construction period, project costs are reduced. This construction method can save on project costs and improve the economic efficiency of engineering construction projects.

[0049] The adjacent shield tunnel and foundation pit in this application are: two shield tunnels are located on both sides of the foundation pit area, and the minimum net distance between the two shield tunnels is ≤max(2D,H) (where D is the diameter of the shield tunnel and H is the excavation depth of the foundation pit).

[0050] In some alternative embodiments, such as Figure 1 As shown, after the initial foundation pit 1 is formed, before the second support mechanism 4 for supporting the retaining wall 3 is installed in the initial foundation pit 1, cement is mixed into the soil using mixing piles to form reinforced soil 10, and the cement is mixed to below the bottom of the target design depth of the target foundation pit 11. The mixing piles thoroughly mix the cement with the soil below the target foundation pit 11, transforming the originally loose soil into reinforced soil 10 with a certain strength and rigidity. Figure 1 As shown, this reinforced soil can withstand greater upper loads and lateral earth pressures. Together with the support structure, it can form a horizontal constraint on the target design depth of the support wall 3, providing a more stable foundation for the excavation of the target pit 11 and subsequent tunnel construction, ensuring the safety of the target pit 11 during construction, and reducing the disturbance of the target pit 11 construction to the surrounding soil, thereby reducing the impact on the shield tunnel 2 construction.

[0051] In some alternative embodiments, such as Figure 3 As shown, after the target pit 11 is formed and the third support structure 5 is set up to support the retaining wall 3, before the shield tunnel 2 is carried out in the remaining side of the shield tunnel 2 area, the second support structure 4 and the third support structure 5 are removed, the main structure 8 is constructed in the target pit 11, and the soil is backfilled on top of the main structure 8.

[0052] Specifically, in practice, before constructing the tunnel 2 crossing on the remaining side of the shield tunnel 2 area, the original third support structure 5 can be removed first, and the bottom structure of the main structure 8 can be constructed. Then, the second support structure 4 can be removed, and the top and other structures of the main structure 8 can be constructed, thus completing the construction of the main structure 8. Soil is then backfilled on top of the main structure 8 to restore the road surface. After the main structure 8 is completed, it possesses significant rigidity and strength. During the subsequent construction of the remaining side of the shield tunnel 2 crossing, soil stress may redistribute, potentially causing soil deformation and displacement. In this case, the main structure 8 and the backfilled soil on top provide reliable lateral support to the sidewall soil of the target pit 11, creating favorable conditions for the construction of the remaining side of the shield tunnel 2 crossing.

[0053] In some alternative embodiments, such as Figure 1 As shown, when the target pit 11 area is excavated to the initial design depth to form the initial pit 1, two capping beams 91 are respectively set on top of the two retaining walls 3 along the length direction. The first support structure 6 is set between the two capping beams 91, and a retaining wall 92 with its top higher than the ground is set on the capping beams 91. The first support structure 6 can be made of concrete and can provide continuous and stable support during the excavation of the target pit 11. After the target pit 11 area is excavated to the initial design depth, two capping beams 91 are set on top of the two retaining walls 3 along the length direction. During the excavation of the target pit 11, the retaining walls 3 will be subjected to lateral pressure from the surrounding soil, and the capping beams 91 can effectively distribute and transmit these pressures, providing a stable support foundation for the subsequently set first support structure 6. The top of the retaining wall 92 is higher than the ground, which can effectively prevent the soil around the target pit 11 from collapsing and sliding into the target pit 11 and prevent rainwater from entering the target pit 11. During the excavation of the target foundation pit 11, the soil around the pit may become loose due to factors such as rainfall and construction vibration. The presence of the retaining wall 92 can prevent these loose soil masses from interfering with the construction inside the target foundation pit 11, and ensure the cleanliness and safety of the construction site inside the target foundation pit 11.

[0054] In summary, the complete construction method of this application consists of the following steps:

[0055] like Figure 1Support walls 3 are installed on both sides of the target pit 11 area and between the two shield tunnel 2 areas;

[0056] Then, the target pit 11 area is excavated to the initial design depth to form the initial pit 1;

[0057] Two capping beams 91 are respectively set on the top of two retaining walls 3 along the length direction, the first support mechanism 6 is set between the two capping beams 91, and a retaining wall 92 with the top higher than the ground is set on the capping beams 91; cement is mixed into the soil using mixing piles to form reinforced soil 10, and the cement is mixed into the soil to below the bottom of the target design depth of the target pit 11.

[0058] like Figure 1 A second support mechanism 4 is installed in the initial foundation pit 1 to support the retaining wall 3, and then the shield tunnel 2 is constructed to pass through one side of the shield tunnel 2 area; such as Figure 4 and Figure 5 After the shield tunnel 2 on this side is completed, a support structure 7 will be installed inside the shield tunnel 2; if Figure 2 Then, the initial foundation pit 1 is excavated to the target design depth to form the target foundation pit 11 and a third support mechanism 5 is set to support the retaining wall 3; the lengths of the second support mechanism 4 and the third support mechanism 5 in the direction between the retaining wall 3 are adjustable.

[0059] like Figure 3 After forming the target pit 11 and setting up the third support structure 5 to support the retaining wall 3, before carrying out the shield tunnel 2 crossing construction on the remaining side of the shield tunnel 2 area, the second support structure 4 and the third support structure 5 are removed, the main structure 8 is constructed in the target pit 11, and the soil is backfilled on top of the main structure 8.

[0060] The shield tunnel 2 crossing construction will be carried out on the remaining side of the shield tunnel 2 area.

[0061] In some alternative embodiments, such as Figure 3 In the vertical direction, the bottom of the main structure 8 is at the same height as the target design depth of the target pit 11.

[0062] In some alternative embodiments, such as Figure 4 and Figure 5When the support structure 7 is installed inside the shield tunnel 2, multiple shield segments 21 are tightly connected along the tunnel axis using tensioning devices, and multiple sets of steel frames for temporary support are installed on the inner wall of the shield segments 21. Connecting multiple shield segments 21 tightly along the tunnel axis using tensioning devices allows the originally independent segments to form a continuous, integrated structure, improving the tunnel's integrity and deformation resistance. When the tunnel construction on one side is completed, and excavation of the target pit 11 continues, the soil around the tunnel will be disturbed by the excavation activities, resulting in varying degrees of deformation. The support structure 7, i.e., the steel frames, can be temporarily connected to the shield segments 21 using bolts. The multiple sets of steel frames installed on the inner wall of the shield segments 21 serve as temporary support structures 7, providing additional support for the segments and preventing the shield segments 21 from being affected by soil deformation and displacement. The steel frame design includes a diagonal cross section, which can effectively distribute the stress, enhance the overall support and resistance to deformation, and prevent the excavation of the target pit 11 from affecting the surrounding soil and thus interfering with the shield tunnel segment 21, ensuring the stability of the tunnel structure and guaranteeing construction safety.

[0063] In some alternative embodiments, a servo system is also included, comprising a CNC pump station, a support head, and a host that drives the support head to extend or retract. The support head is connected to the second support mechanism 4 and the third support mechanism 5 to drive the second support mechanism 4 or the third support mechanism 5 to extend or retract in the direction of the support wall 3.

[0064] In some optional embodiments, when a second support mechanism 4 and a third support mechanism 5 are provided to support the retaining wall 3, a monitoring system is used to monitor the deformation information of the shield tunnel 2, the target pit 11 and the soil around the shield tunnel 2, and the information is transmitted to the servo system.

[0065] In some optional embodiments, when the soil around the shield tunnel 2 is detected to be moving toward the direction of the retaining wall 3, the servo system controls the second support mechanism 4 and the third support mechanism 5 to extend toward the direction of the retaining wall 3 to support the retaining wall 3; when the soil around the shield tunnel 2 is detected not to be moving toward the direction of the retaining wall 3, the servo system controls the second support mechanism 4 and the third support mechanism 5 to retract to or remain in normal working state.

[0066] During construction, the monitoring system continuously monitors the deformation information of the shield tunnel 2, the target pit 11, and the surrounding soil, transmitting the data to the servo system in real time. When the system detects that the soil around the shield tunnel 2 is moving towards the retaining wall 3, it reacts quickly, immediately controlling the second and third support mechanisms 4 and 5 to extend towards the retaining wall 3. This rapid response mechanism provides effective resistance in the early stages of soil deformation, preventing further deformation and displacement, and avoiding safety accidents such as the collapse of the target pit 11 and tunnel damage caused by soil instability, thus providing reliable safety for construction personnel and equipment. In practice, the monitoring system can include conventional components such as inclinometers, stratified settlement gauges, and pore water pressure gauges, which are readily available.

[0067] The servo system precisely controls the extension and retraction of the support head through a CNC pump station. It can accurately adjust the support of the second and third support mechanisms 4 and 5 against the retaining wall 3 based on the actual soil deformation, ensuring the safety and stability of the support process. During the construction of the shield tunnel 2, soil deformation is a dynamic process influenced by various factors, such as the tunneling of the shield machine and changes in the physical properties of the soil. The servo system can monitor soil deformation information in real time and quickly adjust the state of the support mechanisms according to changes, always maintaining effective support for the retaining wall 3. This ability to quickly adapt to dynamic changes allows the support system to better cope with complex construction environments, improving its efficiency and reliability. The second and third support mechanisms 4 and 5 can be made of steel, ensuring the reliability of their support for the retaining wall 3.

[0068] In some optional embodiments, when setting up retaining walls 3 on both sides of the target foundation pit 11, grooves are first dug at the designed locations on both sides of the target foundation pit 11, and then concrete is poured in to form the retaining walls 3. The steps for forming the retaining walls 3 are as follows: first, grooves are dug at the designed locations on both sides of the target foundation pit 11, and then concrete is poured into the grooves; the retaining walls 3 formed by pouring concrete are a continuous integral structure, which can evenly distribute the soil pressure, avoid structural damage caused by local stress concentration, and maintain the stability of the target foundation pit 11.

[0069] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0070] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0071] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for the simultaneous construction of a near-contact shield tunnel and a foundation pit, characterized in that, include: Support walls (3) are set on both sides of the target pit (11) area and between the two shield tunnel (2) areas; then the target pit (11) area is excavated to the initial design depth to form the initial pit (1); the top height of the support wall (3) is lower than the ground and higher than the bottom height of the initial pit (1), and the bottom height of the support wall (3) is lower than the bottom height of the shield tunnel (2) area; A second support mechanism (4) for supporting the retaining wall (3) is set in the initial foundation pit (1), and then the shield tunnel (2) is constructed to pass through the shield tunnel (2) area on one side; after the shield tunnel (2) on that side is completed, a support structure (7) is set in the shield tunnel (2); then the initial foundation pit (1) is excavated to the target design depth to form the target foundation pit (11) and a third support mechanism (5) for supporting the retaining wall (3) is set; the lengths of the second support mechanism (4) and the third support mechanism (5) in the direction between the retaining wall (3) are adjustable; The shield tunnel (2) area on the remaining side was constructed using shield tunneling.

2. The method for cross-construction of adjacent shield tunnels and foundation pits as described in claim 1, characterized in that: After the initial foundation pit (1) is formed, before the second support structure (4) for supporting the retaining wall (3) is set in the initial foundation pit (1), cement is mixed into the soil using mixing piles to form a reinforced soil body (10), and the cement is mixed into the soil to a depth below the target design depth of the target foundation pit (11).

3. The method for cross-construction of adjacent shield tunnels and foundation pits as described in claim 1, characterized in that: After forming the target pit (11) and setting up the third support structure (5) of the support wall (3), before carrying out the shield tunnel (2) crossing construction on the remaining side of the shield tunnel (2), the second support structure (4) and the third support structure (5) are removed, the main structure (8) is constructed in the target pit (11), and the soil is backfilled on top of the main structure (8).

4. The method for cross-construction of adjacent shield tunnels and foundation pits as described in claim 3, characterized in that: In the vertical direction, the bottom of the main structure (8) is at the same height as the target design depth of the target pit (11).

5. The method for cross-construction of adjacent shield tunnels and foundation pits as described in claim 1, characterized in that: When setting up a support structure (7) inside the shield tunnel (2), multiple shield segments (21) are connected tightly along the tunnel axis by a tensioning device, and multiple sets of steel frames for temporary support are set on the inner wall of the shield segments (21).

6. The method for cross-construction of adjacent shield tunnels and foundation pits as described in claim 1, characterized in that: It also includes a servo system, which includes a CNC pump station, a support head and a host that drives the support head to extend and retract. The support head is connected to the second support mechanism (4) and the third support mechanism (5) to drive the second support mechanism (4) or the third support mechanism (5) to extend or retract in the direction of the support wall (3).

7. The method for cross-construction of adjacent shield tunnels and foundation pits as described in claim 6, characterized in that: When setting up the second support mechanism (4) and the third support mechanism (5) for supporting the retaining wall (3), the monitoring system is used to monitor the deformation information of the shield tunnel (2), the target pit (11) and the soil around the shield tunnel (2), and transmit the information to the servo system.

8. The method for cross-construction of adjacent shield tunnels and foundation pits as described in claim 7, characterized in that: When the soil around the shield tunnel (2) is detected to be moving toward the direction of the support wall (3), the servo system controls the second support mechanism (4) and the third support mechanism (5) to extend toward the direction of the support wall (3) to support the support wall (3); when the soil around the shield tunnel (2) is detected not to be moving toward the direction of the support wall (3), the servo system controls the second support mechanism (4) and the third support mechanism (5) to retract to or remain in normal working condition.

9. The method for cross-construction of adjacent shield tunnels and foundation pits as described in claim 1, characterized in that: When setting up retaining walls (3) on both sides of the target pit (11), first cut grooves at the designed positions on both sides of the target pit (11), and then pour concrete to form retaining walls (3).

10. The method for cross-construction of adjacent shield tunnels and foundation pits as described in claim 1, characterized in that: When the target foundation pit (11) area is excavated to the initial design depth to form the initial foundation pit (1), two capping beams (91) are respectively set on the top of two retaining walls (3) along the length direction, the first support mechanism (6) is set between the two capping beams (91), and a retaining wall (92) with the top higher than the ground is set on the capping beams (91).

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