Support jacking device and construction method for tunnel closely passing through existing structure

Abstract

The application proposes a device and construction method for supporting and jacking of tunnel closely underpassing existing structure in order to solve the problem of time limit for grouting compensation when new tunnel closely underpasses existing structure. The jacking support device is divided into inner rod and outer rod, and the end head is designed as two inner and outer grouting cavities, which are respectively fixedly connected with the inner rod and the outer rod, and the inner grouting cavity can move up and down synchronously with the inner rod. The overall structure can be divided into inner rod, outer rod, end head and base. At the base position, the bottom of the inner rod is connected with the bottom of the outer rod through a spring, which can drive the inner rod to move upward during the first grouting jacking, so as to ensure that the top of the inner grouting cavity contacts with the bottom plate of the existing station, and prevent the grouting cavity of the inner rod from not contacting with the bottom plate of the existing station when the second grouting is performed. The grouting pipeline is arranged in the supporting and jacking device, so as to realize the support of the existing structure and the twice grouting jacking, thereby ensuring that the settlement of the existing structure during the whole construction process is within the controllable range.

Description

Technical Field

[0001] This invention belongs to the field of rail transit engineering technology, specifically relating to a device and construction method for supporting and lifting structures that are closely fitted under existing structures. Background Technology

[0002] When a new subway tunnel passes under an existing station or other existing structure, it often causes the existing structure to sink, which reduces the safety of the existing structure. Controlling the sinking of the existing structure is a key issue in the tunnel construction.

[0003] Currently, safety control methods for existing structures during underpass construction can be divided into two categories: passive support and active jacking. Active jacking provides a lifting force to the existing structure to compensate for its settlement. This method is mainly used in the construction of new tunnels closely passing under existing tunnels. Common active jacking measures include grouting jacking and jacking. Jacking jacking uses pre-set jacks to compensate for the settlement of the existing structure through the lifting force. However, the concentrated application of the jacking force can easily lead to increased local stress in the station, posing a risk of cracking during jacking. Grouting jacking can alleviate stress concentration, but grouting is mostly done by injecting grout into the soil on both sides through a pilot tunnel to lift the existing structure. This can only compensate for the settlement during the pilot tunnel excavation stage. After the entire tunnel is excavated, the settlement of the existing structure will further increase, but at this point, the soil in the middle has been excavated, making it impossible to grout again for compensation. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a support and lifting device and construction method for tunnels that closely pass under existing structures. By incorporating grouting pipes within the support and lifting device, the existing structure is supported and lifted twice through grouting, thereby ensuring that the settlement of the existing structure remains within a controllable range throughout the entire construction process.

[0005] The technical solution adopted in this invention is as follows:

[0006] Firstly, the present invention proposes a support and lifting device for tunnels that closely pass under existing structures.

[0007] It includes an outer rod and an inner rod. The top of the outer rod is provided with a first end and the bottom is provided with a base. The first end is hollow to form a first grouting cavity. The outer wall of the first grouting cavity is provided with a first grout outlet hole and the first grouting cavity is connected to a first grouting pipe.

[0008] The inner rod is placed inside the outer rod, and a spring is provided between the inner rod and the base. The spring is controlled by a control device to extend and retract. A second end is provided at the top of the inner rod. The second end is embedded in the inner ring of the first end, and the second end can move upward along the axis of the inner rod under the action of the spring. The inner rod is hollow to form a second grouting cavity. The center of the second end is a check valve, and the check valve is installed at the top of the second grouting cavity.

[0009] As a further technical solution, the surface of the first end and the second end combined in contact with the existing station floor is elliptical.

[0010] As a further technical solution, the first end has a flared shape with a wider top and a narrower bottom along the axis of the outer rod.

[0011] As a further technical solution, a downwardly extending protrusion is provided at the top of the second end, and a groove is provided at the top of the first end, with the protrusion being fitted into the groove.

[0012] As a further technical solution, after the first grouting pipe is inserted from the base, it extends along the axis of the outer rod into the first grouting cavity.

[0013] As a further technical solution

[0014] After the second grouting pipe is inserted from the base, it passes through the spring and extends into the inner rod. The control device is a metal wire. The metal wire is connected to the center of the bottom of the inner rod. The metal wire passes through the spring from the bottom of the inner rod upwards and then fixes the spring downwards along the outer ring from the top of the spring.

[0015] Secondly, the present invention also provides a construction method for a support and lifting device for a tunnel that closely passes under an existing structure, characterized in that...

[0016] Step 1: Excavate the pilot tunnel and then install the aforementioned support and lifting device;

[0017] Step 2: After all the retaining structures inside the pilot tunnel are completed and their strength is tested to meet design requirements, a first grouting and jacking process is performed. The spring control device is released, and the inner rod is lifted to a certain height by the upward force of the spring and the first grouting pressure. Under the action of the high-strength spring force and the grouting pressure, the inner rod is lifted to a certain height, with the second end higher than the first end. The existing station is also lifted to a certain height under the grouting pressure. After the first grouting is completed, the existing station is lifted to a certain height under the grouting pressure of the outer rod. The inner rod and the second end are pressed against the bottom of the existing structure. The load is transferred from the existing station to the first grouting slurry and the outer rod. The jacking support device mainly relies on the first grouting slurry and the outer rod to bear the upper load.

[0018] Step 3: After the longitudinal beams and lining of the new station's roof meet the design requirements, secondary grouting is performed. Grout is injected into the second grouting cavity at the top of the inner pole. The grout flows out along the diversion channel from the second end of the lifting device and exits through the check valve, filling the gap between the support device and the existing station. Under the grouting pressure, the existing station continues to move upward, achieving the effect of secondary grouting and lifting, reducing station settlement. At this time, part of the station's load is transferred to the first grout and the outer pole through the second grout, and the upper load is mainly borne by the structure formed by the two grouts and the outer pole.

[0019] As a further technical solution, in step 1, after excavating the pilot tunnel, bored piles are constructed while the pilot tunnel is being excavated. After the piles are formed, grouting is performed at the bottom of the piles, and a pile top support beam is constructed. The aforementioned support and lifting device is arranged on the upper part of the pile top support beam.

[0020] As a further technical solution, in step 1, the supporting jacking device is arranged in the same position as the bored pile, with its top directly contacting the existing station floor slab, and then the guide tunnel lining support structure is constructed.

[0021] As a further technical solution, during construction, the long side of the elliptical cross-section of the first and second ends is parallel to the width of the pilot tunnel excavation face.

[0022] The beneficial effects of the above embodiments of the present invention are as follows:

[0023] 1. The grouting and jacking support device proposed in this invention solves the problem that traditional grouting and jacking devices cannot perform secondary grouting by setting up inner and outer grouting cavities. It performs overall grouting and jacking in two stages: after the guide tunnel is completed and after the soil in the middle of the guide tunnel is excavated. This compensates for the settlement of the existing station caused by the two stages and ensures that the settlement of the existing structure is within a controllable range throughout the entire construction process.

[0024] 2. To reduce stress concentration during the grouting and jacking process, the end of the jacking support device is designed as a trumpet shape with a thicker top and a thinner bottom. This increases the contact area and reduces the pressure on the existing station floor during the jacking process.

[0025] 3. The combined first and second ends of the jacking support device form an elliptical surface that contacts the existing station floor slab. Multiple grout outlets are located along the edge and top of the first end, while a check valve is installed in the center of the second end. This design increases the grout diffusion area during grouting and jacking, transforming point diffusion into line diffusion and improving the grouting and jacking effect. The long side of the elliptical cross-section is parallel to the width of the pilot tunnel excavation face, strengthening the connection between different pilot tunnels and improving the overall integrity of the construction process.

[0026] 4. The top two sides of the second end are designed to be bent downwards, which makes it easier to withstand the grouting pressure. Under the action of grouting pressure and spring force, the second end is higher than the first end, preventing the grout from blocking the check valve during the first grouting. A grout stop pad connected to the inner wall of the first grouting chamber is used to fill the gap between the pad and the inner rod, preventing the grout from flowing into the base spring position and affecting the operation of the high-strength spring. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0028] Figure 1 This is a schematic diagram of the lifting support device proposed in this invention;

[0029] Figure 2 This is a schematic cross-sectional view of the lifting support device proposed in this invention;

[0030] Figure 3 This is a schematic diagram of the structure of the lifting support device after assembly at the end, as proposed in this invention.

[0031] Figure 4(a) is a schematic diagram of the structure of the first end of the lifting support device of the present invention;

[0032] Figure 4(b) is a schematic diagram of the structure of the second end of the lifting support device of the present invention;

[0033] Figure 5(a) is a front cross-sectional view of the base of the present invention;

[0034] Figure 5(b) is a cross-sectional perspective view of the base of the present invention;

[0035] Figure 6 This is a schematic diagram of the lead screw installation of the present invention;

[0036] Figure 7 yes Figure 6 AA section view;

[0037] Figure 8 It is a schematic diagram of the installation of the lifting support device, pile top support beam, and guide tunnel;

[0038] Figure 9 This is a schematic diagram of the initial stage of the lifting process;

[0039] Figure 10 This is a schematic diagram of the overall structure during a lifting phase;

[0040] Figure 11 This is a schematic diagram of the invention during a single lifting stage;

[0041] Figures 12(a) and 12(b) are schematic diagrams of the second lifting stage;

[0042] Figure 13 This is a schematic diagram of the second stage of the jacking process;

[0043] In the diagram: 1-grouting pipe, 2-end, 2-1 first end, 2-2 second end, 3-outer rod, 4-base, 5-first grout outlet, 6-second grouting chamber, 7-first grouting chamber, 8-inner rod, 9-outer grouting pipe, 10-check valve, 11-inner grouting pipe, 12-high-strength spring, 13-surrounding soil, 14-existing station, 15-guide tunnel lining, 16-jacking support device, 17-pile top support beam, 18-guide tunnel, 19-drilled pile, 20-top longitudinal beam, 21-top plate, 22-first grouting slurry, 23-secondary grouting slurry, 24-iron wire, 25-bolt, 26-grout stop pad; Detailed Implementation

[0044] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0045] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0046] Definition: In this invention, it is assumed that the main structure of the end is annular, then the centripetal side is the inner side and the centrifugal side is the outer side. Based on this basic orientation, the inner and outer sides in this invention are accurately defined.

[0047] As described in the background section, there are shortcomings in the existing technology. In order to solve the above-mentioned technical problems, this invention proposes a support and lifting device and construction method for tunnels closely passing under existing structures.

[0048] In a typical embodiment of the present invention, such as Figures 1-3As shown, the tunnel support and lifting device for closely following an existing structure disclosed in this embodiment includes an inner rod 8 and an outer rod 3. The bottom of the outer rod 3 is a base 4, and the top is a first end 2-1. The base 4, outer rod 3, and first end 2-1 are coaxially installed. A cavity is set in the center of the base 4, outer rod 3, and first end 2-1 for installing the inner rod 8. The first end 2-1 is a cavity structure, forming a first grouting cavity 7. A first grout outlet hole is set around the outer wall of the first end. The first grouting cavity 7 is connected to an outer grouting pipe 9 extending upward from the base 4. Grout is injected into the first grouting cavity 7 through the outer grouting pipe 9, and the grout comes out from the first grout outlet hole 5 of the first grouting cavity 7. A grout-stopping pad is connected to the outer side of the inner wall of the first grouting cavity to fill the upper gap between the inner rod and the grouting pad, preventing the grout from flowing into the lower spring position of the inner rod.

[0049] The inner rod 8 is installed in the cavity at the center of the base 4, the outer rod 3, and the first end 2-1. A spring 12 is installed between the bottom of the inner rod 8 and the outer rod base. The top two sides of the second end 2-2 have a downward-bending structure, which can easily withstand the grout pressure of the first grouting. A check valve 10 is fixed in the middle of the top of the end, so that the grout can only flow out from the inside of the inner rod. The check valve 10 is nested in the end of the first end 2-1. The second end 2-2 and the interior of the inner rod are also a cavity, forming a second grouting cavity. An inner grouting pipe is fixed on the base. The inner grouting pipe injects grout into the second grouting cavity, and then the grout exits from the check valve 10 at the top of the second grouting cavity.

[0050] The lifting support device in this embodiment is divided into an inner rod 8 and an outer rod 3. The aforementioned end includes two sections, forming two independent grouting chambers. One section is fixedly connected to the inner rod 8 and can move up and down synchronously with the inner rod 8; the other section is fixedly connected to the outer rod 3. At the base 4, the bottom of the inner rod 8 is connected to the bottom of the outer rod 3 via a spring. The spring 12 can drive the inner rod 8 upward during the first grouting lifting, ensuring that the top of the second grouting chamber 6 contacts the existing station floor slab, preventing the grout injected from the second grouting chamber 6 of the inner rod from failing to contact the existing station floor slab during secondary grouting. Furthermore, the bottom of the inner rod 8... The inner rod 8 is connected by wire 24, with both ends fixed to the bottom of the inner rod. When bolt 25 is tightened, wire 24 loops around the bolt passing through the lower outer rod base, thus fixing wire 24 in place and preventing the inner rod 8 from moving. The second end of the inner rod 8 is embedded in the groove of the first end, and the top of the inner rod 8 is flush with the top of the outer rod. The high-strength spring 12 is compressed, loosening bolt 25 outward. When wire 24 is released from the bolt 25, the inner rod 8 moves upward under the upward force of the high-strength spring 12, ensuring that the top of the second grouting chamber contacts the existing station floor slab. This prevents the grout injected from the second grouting chamber of the inner rod from failing to contact the existing station floor slab during secondary grouting. Furthermore, the elastic force of the high-strength spring 12 and the pressure of the first grouting can make the second end higher than the first end, preventing grout leakage from blocking the check valve during the first grouting.

[0051] The transverse cross-section of the end portion of the lifting support device is elliptical, that is, the surface where the first end 2-1 and the second end 2-2 are combined and contact the existing station floor is elliptical; and in order to avoid stress concentration and damage to the existing station, the cross-section along the axis of the outer rod 3 is designed as follows: the first end 2-1 is designed as a trumpet shape that is wider at the top and narrower at the bottom (as shown in Figure 4(a)), and the second end is designed as a shape with the top two sides bent downwards (as shown in Figure 4(b)), which makes it easier to withstand the pressure of the lower grout. In addition, a check valve is set in the middle of the top of the second end so that the grout can only flow out from the second grouting chamber. The first end and the second end can expand the diffusion area of ​​the grout and reduce the pressure during grouting.

[0052] Before the bolts are loosened, when the high-strength spring is under compression, the second end is precisely embedded in the groove formed at the end of the first end. When the lifting support device contacts the existing station floor, the first grouting begins, and the bolts are loosened. Under the action of the first grouting pressure and the elastic force of the high-strength spring, the inner rod springs upward, and the second end is higher than the first end. The existing station is also lifted to a certain height under the grouting pressure. The inner rod and the connected second end are always in contact with the existing station floor under the action of the spring force and the first grouting pressure, allowing for secondary grouting.

[0053] Eight equidistant first grout outlet holes are provided on the outer ring sidewall and upper part of the first end. Except for the grout outlet holes, the outer grouting cavity is completely closed. The outer side of the inner wall of the first grouting cavity is connected to the grout stop pad to fill the gap between the first grouting cavity and the upper part of the inner rod, so as to prevent the grout from flowing into the lower part of the inner rod at the spring position.

[0054] The base is made of high-strength rigid material. There are two grouting holes on the side wall of the outer pole base, along with a bolt device. One grouting hole connects to the inner pole's grouting cavity, and the other connects to the first grouting cavity. The inner pole is connected to the outer pole base via a high-strength spring. The base has bolt holes at the wire insertion points, with openings to facilitate wire insertion. A wire is connected to the lower part of the inner pole base, with both ends connected to the bottom of the inner pole, forming a loop. Before installation, the bolts are tightened, and the wire loop is secured to the bolts passing through the lower base, preventing the inner pole from moving. The second end of the inner pole is embedded in the groove of the first end, with the top of the inner pole flush with the top of the outer pole. The high-strength spring is compressed, loosening the bolts outwards. When the wire is released from the bolts, the inner pole is subjected to the upward force of the high-strength spring, ensuring that the top of the second end contacts the existing station floor slab. This prevents the grout injected from the second grouting cavity of the inner pole from failing to contact the existing station floor slab during secondary grouting. Furthermore, the spring force and the pressure of the first grouting can cause the inner rod to move upward, making the second end higher than the first end, thus preventing grout from leaking out and blocking the check valve during the first grouting.

[0055] Based on the above-described device, this embodiment also discloses a method for arranging and using a supporting lifting device, as detailed below:

[0056] (1) Arrangement of pilot tunnel excavation and jacking support device

[0057] After excavating the pilot tunnel 18, bored piles 19 are constructed simultaneously with the pilot tunnel excavation. After the piles are completed, a pile top support beam 17 is constructed. The aforementioned support and lifting device is arranged on top of the pile top support beam 17, ensuring that the shorter side of the elliptical cross-section at the end is aligned with the excavation direction of the pipe roof. The support and lifting device is positioned similarly to the bored piles 17, with its top directly contacting the existing station 14's base slab. Then, the pilot tunnel lining 15 support structure is constructed. During installation, to facilitate grouting, the grouting pipe of the lifting support device should extend outside the pilot tunnel 18. During the installation phase, the lifting support device provides a certain level of support. After the pilot tunnel 18 is completed, the top longitudinal beam 20 is constructed. The soil in the middle of the pilot tunnel is then excavated, and the top slab 21 is constructed.

[0058] (2) First overall lifting stage

[0059] To prevent excessive settlement of the existing station during subsequent construction phases, the existing station must first be jacked up as a whole. After all the retaining structures inside the pilot tunnel are completed and their strength is tested to meet design requirements, the first grouting begins, and the bolts are loosened. Under the upward elastic force of the springs and the pressure of the first grouting, the inner rod is lifted to a certain height, with the second end higher than the first end. The existing station is also jacked up to a certain height under the grouting pressure. After the first grouting is completed, the existing station is lifted to a certain height under the grouting pressure of the outer rod. The inner rod and the second end are pressed tightly against the bottom of the existing structure. The load is transferred from the existing station to the first grouting slurry and the outer rod. The jacking support device mainly relies on the first grouting slurry and the outer rod to bear the upper load.

[0060] Step 3: Second grouting and jacking compensation

[0061] After the pilot tunnel construction was completed, the excavation of the underpass section continued, causing the existing structure to experience premature settlement. To compensate for the settlement of the existing station caused by the excavation of the underpass section's roof slab, a secondary grouting and jacking stage was conducted once the new station's top longitudinal beams and roof lining met design requirements. Compensatory grouting was performed on the second grouting chamber of the inner rod. The grout flowed out along the diversion channel from the second end of the jacking device, exiting through a check valve to fill the gap between the support device and the existing station. Under the grouting pressure, the existing station continued to move upwards, achieving the effect of secondary grouting and jacking, thus reducing station settlement. At this point, part of the station's load was transferred to the first grouting grout and the outer rod through the second grouting grout. The upper load was mainly borne by the structure formed by the two grouting grouts and the outer rod.

[0062] (1) The grouting and lifting support device proposed in this invention solves the problem that traditional grouting and lifting devices cannot perform secondary grouting by setting up two layers of grouting cavities, and performs overall grouting and lifting in two stages: after the guide tunnel is completed and after the soil in the middle of the guide tunnel is excavated. This compensates for the settlement of the existing station caused by the two stages and ensures that the settlement of the existing structure is within a controllable range throughout the entire construction process.

[0063] (2) In order to reduce the stress concentration phenomenon during the grouting and jacking process, the end of the jacking support device is designed as a trumpet shape with a thicker top and a thinner bottom. By increasing the contact area, the pressure on the existing station floor during the jacking process is reduced.

[0064] (3) The first and second ends of the jacking support device are combined to form an elliptical surface that contacts the existing station floor slab. Multiple grout outlets are provided along the edge and top of the first end, and a check valve is provided in the middle of the second end. During the grouting and jacking process, the diffusion area of ​​the grout can be increased, transforming the point diffusion of the grout into line diffusion and improving the grouting and jacking effect. The long side of the elliptical cross-section is parallel to the width of the guide tunnel excavation face, strengthening the connection between different guide tunnels and improving the overall integrity of the construction process.

[0065] (4) The top two sides of the second end are designed to be bent downwards, which makes it easier to withstand the grouting pressure. The second end is higher than the first end under the action of grouting pressure and spring force, which prevents the grout from blocking the check valve. The grouting pad connected to the inner wall of the first grouting cavity is used to fill the gap between the inner rod and the grouting pad, which prevents the grout from flowing into the base spring position and affecting the operation of the high-strength spring.

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A support and lifting device for tunnels closely following existing structures, characterized in that, It includes an outer rod and an inner rod. The top of the outer rod is provided with a first end and the bottom is provided with a base. The first end is hollow to form a first grouting cavity. The outer wall of the first grouting cavity is provided with a first grout outlet hole and the first grouting cavity is connected to a first grouting pipe. The inner rod is placed inside the outer rod, and a spring is provided between the inner rod and the base. The spring is controlled by a control device to extend and retract. A second end is provided at the top of the inner rod. The second end is embedded in the inner ring of the first end, and the second end can move upward along the axis of the inner rod under the action of the spring. The inner rod is hollow to form a second grouting cavity. The center of the second end is a check valve, and the check valve is installed at the top of the second grouting cavity. After the first grouting pipe is inserted from the base, it extends along the axis of the outer rod into the first grouting cavity; After the second grouting pipe is inserted from the base, it passes through the spring and extends into the inner rod. The control device is a metal wire. The metal wire is connected to the center of the bottom of the inner rod. The metal wire passes through the spring from the bottom of the inner rod upwards and then fixes the spring downwards along the outer ring from the top of the spring.

2. The support and lifting device for tunnels closely passing under existing structures as described in claim 1, characterized in that, The surface where the first end and the second end meet in contact with the existing station floor is elliptical.

3. The support and lifting device for tunnels closely passing under existing structures as described in claim 1, characterized in that, The first end has a flared shape in cross-section along the axis of the outer rod, which is wider at the top and narrower at the bottom.

4. The support and lifting device for tunnels closely passing under existing structures as described in claim 1, characterized in that, The second end has a downward-extending protrusion at its top, and the first end has a groove at its top, with the protrusion fitting into the groove.

5. A construction method for a support and lifting device for a tunnel closely passing under an existing structure as described in any one of claims 1-4, characterized in that, Step 1: Excavate the pilot tunnel and then install the aforementioned support and lifting device; Step 2: After all the retaining structures in the pilot tunnel are completed and the strength is tested to meet the design requirements, a grouting and jacking process is carried out. The spring control device is released, and the inner rod is lifted to a certain height by the upward elastic force of the spring and the grouting pressure. Under the action of the high-strength spring force and the grouting pressure, the inner rod is lifted to a certain height, with the second end higher than the first end. The existing station is also lifted to a certain height under the grouting pressure. After the first grouting is completed, the existing station is lifted to a certain height under the grouting pressure of the outer rod. The inner rod and the second end are close to the bottom of the existing structure. The load is transferred from the existing station to the first grouting slurry and the outer rod. The jacking support device mainly relies on the first grouting slurry and the outer rod to bear the upper load. Step 3: After the top longitudinal beams and top slab lining of the newly built station meet the design requirements, secondary grouting is carried out. Grouting is performed on the second grouting cavity at the top of the inner rod. The grout flows out of the second end of the lifting device along the diversion channel and flows out through the check valve to fill the gap between the support device and the existing station. Under the action of grouting pressure, the existing station continues to move upward, achieving the effect of secondary grouting and lifting, reducing the settlement of the station. At this time, part of the station load is transferred to the first grouting grout and the outer rod through the second grouting grout. The upper load is mainly borne by the structure formed by the two grouting grouts and the outer rod.

6. The construction method of a support and jacking device for a tunnel closely passing under an existing structure as described in claim 5, characterized in that, In step 1, after excavating the pilot tunnel, bored piles are constructed while the pilot tunnel is being excavated. After the piles are formed, grouting is performed at the bottom of the piles, and a pile top support beam is constructed. The aforementioned support and lifting device is arranged on the upper part of the pile top support beam.

7. The construction method of a support and jacking device for a tunnel closely passing under an existing structure as described in claim 6, characterized in that, In step 1, the supporting jacking device is positioned in the same location as the bored pile, with its top directly contacting the existing station floor slab, and then the guide tunnel lining support structure is constructed.

8. The construction method of a support and jacking device for a tunnel closely passing under an existing structure as described in claim 5, characterized in that, During construction, the long side of the elliptical cross-section of the first and second ends is parallel to the width of the pilot tunnel excavation face.

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