Device and method for controlling underlying operation shield tunnel upheaval caused by foundation pit excavation

Abstract

The invention relates to the technical field of civil engineering and foundation pit supporting, in particular to a device and method for controlling upheaval of an underlying operation shield tunnel caused by foundation pit excavation. A device for controlling upheaval of an underlying operation shield tunnel caused by excavation of a foundation pit comprises a steel plate which is used for being inserted into a soil layer above an existing operation tunnel and bearing soil pressure to control upheaval of the tunnel when the foundation pit is excavated above the tunnel; and the supporting assembly is used for supporting the two ends of the steel plate and further improving the rigidity of the supporting system. The steel plate is inserted above the tunnel, the supporting assembly is combined for supporting, the brand-new tunnel deformation control method is formed, the method can effectively resist soil displacement in the excavation process, the upward floating amplitude of the tunnel is reduced, the stability of the tunnel structure in the construction process is ensured, and the method has good application prospects and is suitable for popularization and application. The defects in the prior art can be effectively overcome, and the tunnel protection technology has high economic benefits and social benefits.

Description

Technical Field

[0001] The invention relates to the technical field of civil engineering and foundation pit support, and in particular to a device and method for controlling the uplift of an underlying operating shield tunnel caused by foundation pit excavation. Background Art

[0002] In the development of urban underground space, it is inevitable to excavate foundation pits near existing operating tunnels or underground structures. During the foundation pit excavation process, due to the unloading effect of the soil, the underlying tunnel or other underground structures may rise, causing tunnel deformation and safety hazards.

[0003] Existing tunnel protection measures usually include reducing the excavation range and reinforcing the tunnel structure. These existing tunnel protection measures have the following limitations: (1) Tunnel uplift problem: During the excavation of the foundation pit, the unloading of the soil is likely to cause the tunnel to float and deform, which has an adverse effect on the tunnel structure and even threatens the normal use and safe operation of the tunnel. (2) Low construction efficiency: Traditional tunnel protection measures, especially the practice of large-scale reinforcement of the soil above the tunnel, have a cumbersome construction process and a long cycle, which is not conducive to the rapid advancement of the project and cannot meet the requirements of a tight construction cycle. In addition, the cost of reinforcing the tunnel or setting up a reinforcement layer is high and the construction is complicated. At the same time, these methods have limited effects in controlling soil deformation and it is difficult to accurately control the uplift and floating of the tunnel. (3) Insufficient stiffness of the support system: During the excavation process, it is difficult to provide sufficient support stiffness, resulting in excessive displacement of the soil above the tunnel during the excavation process. (4) Most of the existing technologies require construction work to be carried out in an operating tunnel. However, in actual situations, trains need to pass through the tunnel, and there are many equipments in the tunnel. Carrying out work in an operating tunnel will affect the operation and safety of the existing trains in the operating tunnel. The present invention completely carries out the work outside the operating tunnel, thus avoiding this limitation.

[0004] Therefore, the present invention proposes a new construction method to solve the above-mentioned technical problems by designing a device combining a steel plate and a support assembly; this method first excavates the foundation pits on both sides before excavating the soil above the tunnel, inserts steel plates into the excavated areas, and uses support assemblies for support, thereby achieving segmented support for the soil above the tunnel, thereby effectively controlling the uplift of the tunnel. Summary of the invention

[0005] The purpose of the present invention is to provide a device and method for controlling the uplift of an underlying operating shield tunnel caused by foundation pit excavation, which is used to solve the prior art problems raised in the background technology: tunnel uplift problems, low construction efficiency, and insufficient rigidity of the support system.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a device for controlling the uplift of an underlying operating shield tunnel caused by foundation pit excavation, comprising:

[0008] Steel plates are used to be inserted into the soil layer above the existing operating tunnel to bear the soil pressure and control the uplift of the tunnel when the foundation pit is excavated above the tunnel;

[0009] The support assembly is used to support both ends of the steel plate to further increase the rigidity of the support system.

[0010] Furthermore, the support assembly includes:

[0011] A support frame, the support frame comprising a crossbar and vertical bars fixed at both ends of the crossbar;

[0012] A threaded upper rod, the threaded upper rod is fixed to the bottom of the two vertical rods of the support frame, the threaded upper rod is cylindrical, and a thread is arranged on the outer side;

[0013] The inner thread lower rod is cylindrical and has threads inside. The inner thread lower rod is threadedly connected to the threaded upper rod to adjust the height of the support assembly when rotating.

[0014] Furthermore, the support assembly also includes a chassis, which is fixed to the bottom of the internally threaded lower rod to increase the support area.

[0015] Furthermore, X-shaped channel steels are arranged between the vertical bars of the support frame.

[0016] Furthermore, the support frame, threaded upper rod, internally threaded lower rod, chassis, and X-shaped channel steel are all made of Q345 material.

[0017] Furthermore, the outer side of the top of the internally threaded lower rod is provided with anti-skid grooves and / or an anti-skid rubber layer.

[0018] The present invention also provides a method for controlling the uplift of an underlying operating shield tunnel caused by foundation pit excavation, comprising the following steps:

[0019] Excavation of working pits on both sides of the foundation pit: excavation of working pit areas on both sides above the existing operating tunnel;

[0020] Steel plate insertion: After the construction of the working pit area is completed, the steel plate is inserted from the soil layer above the existing operating tunnel; the size of the steel plate covers the excavation range above the existing operating tunnel;

[0021] Installation of support assembly: Place the support assembly under the steel plate, and then rotate the two internal threaded lower rods of the support assembly respectively, so that the support assembly is raised under the action of the threads until the top support frame completely rests against the bottom surface of the steel plate;

[0022] Foundation pit excavation: After the steel plate and support components are installed, the foundation pit soil excavation work is carried out on the steel plate;

[0023] Excavation in sections: After the excavation of the foundation pit above the existing operating tunnel is completed each time, the above steps are repeated along the longitudinal direction of the existing operating tunnel to carry out the work of the next section of the excavation area;

[0024] Foundation pit excavation completed: Repeat the above steps until the foundation pit excavation above the entire tunnel is completed.

[0025] The present invention has at least the following beneficial effects:

[0026] (1) The present invention forms a new tunnel deformation control method by inserting a steel plate above the tunnel and combining it with a support assembly for support. This method can effectively resist soil displacement during excavation, reduce the buoyancy of the tunnel, and ensure the stability of the tunnel structure during construction.

[0027] (2) The device design of the present invention enables it to be constructed in sections along the longitudinal direction of an existing operating tunnel. With the construction method of excavating section by section, the need for processing large areas of soil is reduced, thereby greatly improving construction efficiency and shortening the project period. Compared with traditional methods, this method is easier to install and move, and can adapt to complex construction environments.

[0028] (3) Cost saving and construction flexibility: The device of the present invention has a simple design and does not require a large number of reinforcement measures during construction. The material cost and construction cost are relatively low. At the same time, the mobility of the device enables it to adapt to the excavation requirements of foundation pits above tunnels of different lengths, making the construction operation more flexible.

[0029] (4) Enhanced support stiffness and stability: The support assembly of the present invention enables the device to have higher resistance to lateral deformation and support stiffness, ensuring the stability of the support system during foundation pit excavation and reducing structural risks caused by lateral displacement.

[0030] (5) Environmental friendliness and improved safety: Since the device can avoid large-scale soil disturbance, it reduces the impact on the underground environment. At the same time, through reasonable support design, it reduces ground subsidence and tunnel deformation caused by excavation, thereby improving the safety of the entire project.

[0031] (6) The present invention performs operations entirely outside the operating tunnel, thus avoiding the limitation that most existing technologies require construction operations to be performed inside the operating tunnel, which affects the operation and safety of trains in the existing operating tunnel.

[0032] The present invention significantly improves the effect of tunnel deformation control during foundation pit excavation through innovative support structures and construction methods. It has good application prospects and can effectively overcome the deficiencies in the prior art. It is a tunnel protection technology with high economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0034] Figure 1 It is an overall schematic diagram of the device of the present invention;

[0035] Figure 2 It is a schematic diagram of the support assembly of the present invention;

[0036] Figure 3 It is a schematic diagram of the device and tunnel section;

[0037] Figure 4 It is a top view of the foundation pit excavation area;

[0038] Figure 5 Grid diagram for foundation pit excavation;

[0039] Figure 6 Deformation diagram of tunnel and steel plate mesh;

[0040] Figure 7 This is the tunnel uplift displacement cloud diagram when no steel plate device is added;

[0041] Figure 8 This is the tunnel uplift displacement cloud diagram when the steel plate device is added;

[0042] Fig. 9 It is the displacement cloud diagram of steel plate.

[0043] In the figure: 1. steel plate; 2. support assembly; 21. support frame; 22. threaded upper rod; 23. internally threaded lower rod; 24. chassis; 25. X-shaped channel steel. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0045] Example 1

[0046] This embodiment mainly discloses a device for controlling the uplift of an underlying operating shield tunnel caused by foundation pit excavation.

[0047] See also Figure 1-Figure 2 The device is mainly composed of a steel plate 1 and a supporting component 2.

[0048] The steel plate 1 is used to be inserted into the soil layer above the existing operating tunnel, so as to withstand the soil pressure and control the uplift of the tunnel when the foundation pit is excavated above the existing operating tunnel.

[0049] The support assembly 2 is used to further support both ends of the steel plate 1, so as to further increase the rigidity of the support system.

[0050] Specifically, the support assembly 2 includes:

[0051] A support frame 21, the support frame 21 includes a crossbar and vertical bars fixed at both ends of the crossbar;

[0052] A threaded upper rod 22, which is fixed to the bottom of the two vertical rods of the support frame 21, and is cylindrical with threads on the outside;

[0053] The internal thread lower rod 23 is cylindrical and has threads inside. The internal thread lower rod 23 is threadedly connected to the threaded upper rod 22 and can be rotated to adjust the height of the entire support assembly 2;

[0054] The chassis 24 is fixed to the bottom of the internally threaded lower rod 23 to increase the supporting area.

[0055] In other embodiments, X-shaped channel steels 25 are further provided between the vertical bars of the support frame 21 and fixed by welding. The arrangement of the X-shaped channel steels 25 can effectively enhance the anti-lateral displacement performance of the device and ensure the stability of the device during excavation.

[0056] In other preferred embodiments, the support frame 21, the threaded upper rod 22, the internally threaded lower rod 23, the chassis 24, and the X-shaped channel steel 25 can all be made of Q345 material.

[0057] In a general embodiment, after the height of the support frame 21 is adjusted, the cross bar of the support frame 21 can be directly used to support the bottom surface of the steel plate 1; in other embodiments, screws can be used to further fix the cross bar of the support frame 21 and the steel plate 1 to achieve a tighter connection.

[0058] In a specific embodiment, in order to facilitate the rotation of the internally threaded lower rod 23 , anti-skid facilities such as anti-skid grooves and an anti-skid rubber layer may be provided on the outer side of the top of the internally threaded lower rod 23 .

[0059] Example 2

[0060] This embodiment mainly discloses a method for controlling the uplift of an underlying operating shield tunnel caused by foundation pit excavation, and the device adopts the device as described in the above embodiment.

[0061] See also Figure 3-Figure 4 In order to achieve the design purpose of the present invention, the main specific construction method steps are as follows:

[0062] Step 1: Excavation of working pits on both sides of the foundation pit: First, excavate the working pit area on both sides above the existing operating tunnel. According to the design requirements, the width and depth of the working pit area must meet the engineering standards to ensure the installation of subsequent devices and the laying of mobile tracks.

[0063] Step 2: Insertion of steel plate 1: After the construction of the working pit area is completed, a steel plate 1 is inserted from the soil layer above the existing operating tunnel. The size of the steel plate should cover the excavation range above the existing operating tunnel, and its thickness should be sufficient to withstand the soil pressure.

[0064] Step 3: Install the support assembly 2: Place the support assembly 2 under the steel plate 1, and then rotate the two internally threaded lower rods 23 of the support assembly 2 respectively, so that the support assembly 2 is raised under the action of the threads until the top support frame 21 completely rests against the bottom surface of the steel plate 1.

[0065] Step 4: Excavation of foundation pit: After the steel plate 1 and the support assembly 2 are installed, the foundation pit soil is excavated on the upper side of the steel plate 1;

[0066] Step 5: Excavation in sections: After completing the excavation of the foundation pit soil above the existing operating tunnel each time, repeat the above steps along the longitudinal direction of the existing operating tunnel to carry out the work in the next excavation area, and repeat the operation of installing the steel plate 1 and the fixed support assembly 2 to ensure that the soil above the tunnel is effectively supported during each excavation.

[0067] Step 6: Foundation pit excavation completed: Repeat the above steps until the foundation pit excavation above the entire tunnel is completed.

[0068] The device avoids the problem of tunnel uplift caused by large-scale excavation by supporting the excavated soil section by section. In practical applications, the device can be adjusted according to different engineering conditions. For example, when the soil above the tunnel is relatively loose, the thickness of the steel plate 1 can be appropriately increased, or more support components 2 can be added at both ends of the steel plate 1 to increase the support strength and further enhance the support effect. In summary, the present invention provides a foundation pit excavation support device with a simple structure, convenient installation, and strong adaptability, which can effectively solve the problem of tunnel uplift caused by excavation in the prior art, and has strong practicality and broad application prospects.

[0069] In order to further illustrate the effect of the device and method of the present invention, we also conducted a digital simulation verification. Figure 5-Figure 9 , the verification process and results are as follows:

[0070] We used PLAXIS 3D finite element simulation software to build a 30m×50m×9m foundation pit model to study the impact of this device on the deformation of the existing underlying tunnel. According to the PLAXIS 3D simulation results, the uplift displacement of the tunnel before and after the installation of the steel plate support device was compared. It can be clearly seen that the steel plate support can significantly reduce the uplift displacement of the tunnel during the foundation pit excavation process. Figure 7 The maximum uplift displacement of the tunnel is large, and the displacement is mainly concentrated in the central area of ​​the tunnel. After the steel plate support is installed, Figure 8 The results show that the uplift displacement of the tunnel is significantly reduced, and the displacement distribution is more uniform. It can be seen that the steel plate support can effectively control the deformation of the tunnel during the excavation process and enhance the overall stability of the tunnel. This proves that the support system has a significant effect on reducing the uplift displacement of the tunnel during foundation pit excavation construction, which helps to ensure the safety of the tunnel and surrounding structures.

[0071] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A device for controlling the uplift of an underlying operating shield tunnel caused by excavation of a foundation pit, characterized in that: include: Steel plates are used to be inserted into the soil layer above the existing operating tunnel to bear the soil pressure and control the uplift of the tunnel when the foundation pit is excavated above the tunnel; The support assembly is used to support both ends of the steel plate to further increase the rigidity of the support system.

2. The device for controlling the uplift of the underlying shield tunnel caused by foundation pit excavation according to claim 1 is characterized in that: The support assembly comprises: A support frame, the support frame comprising a crossbar and vertical bars fixed at both ends of the crossbar; A threaded upper rod, the threaded upper rod is fixed to the bottom of the two vertical rods of the support frame, the threaded upper rod is cylindrical, and a thread is arranged on the outer side; The internally threaded lower rod is cylindrical and has threads arranged inside. The internally threaded lower rod is threadedly connected to the threaded upper rod and is used to adjust the height of the support assembly during rotation.

3. The device for controlling the uplift of the underlying shield tunnel caused by foundation pit excavation according to claim 2 is characterized in that: The support assembly also includes a chassis, which is fixed to the bottom of the internally threaded lower rod to increase the support area.

4. The device for controlling the uplift of the underlying operating shield tunnel caused by foundation pit excavation according to claim 3 is characterized in that: X-shaped channel steels are also arranged between the vertical rods of the support frame.

5. According to the device for controlling the uplift of the underlying operating shield tunnel caused by foundation pit excavation as described in claim 4, the support frame, threaded upper rod, internally threaded lower rod, chassis, and X-shaped channel steel are all made of Q345 material.

6. According to the device for controlling the uplift of the underlying operating shield tunnel caused by foundation pit excavation as described in claim 2, the top outer side of the internally threaded lower rod is provided with anti-skid grooves and / or an anti-skid rubber layer.

7. A method for controlling the uplift of an underlying operating shield tunnel caused by excavation of a foundation pit, characterized in that: The following steps are involved: Excavation of working pits on both sides of the foundation pit: excavation of working pit areas on both sides above the existing operating tunnel; Steel plate insertion: After the construction of the working shaft area is completed, the steel plate is inserted from the soil layer above the existing operating tunnel; The size of the steel plates covers the excavation above the existing operational tunnel; Installation of support assembly: Place the support assembly under the steel plate, and then rotate the two internal threaded lower rods of the support assembly respectively, so that the support assembly is raised under the action of the threads until the top support frame completely rests against the bottom surface of the steel plate; Foundation pit excavation: After the steel plate and support components are installed, the foundation pit soil excavation work is carried out on the steel plate; Excavation in sections: After the excavation of the foundation pit above the existing operating tunnel is completed each time, the above steps are repeated along the longitudinal direction of the existing operating tunnel to carry out the work of the next section of the excavation area; Foundation pit excavation completed: Repeat the above steps until the foundation pit excavation above the entire tunnel is completed.

Images