A mobile shield device and method for full-section excavation of soft rock tunnel

Abstract

A mobile shield device and method for full-section excavation of a soft rock tunnel, comprising a front shield, a middle shield, and a rear shield. The middle shield is a ring-shaped closed structure matching the tunnel section. Both sides of the front shield are provided with inclined surfaces inclined from the front end of the front shield to the middle shield. The rear shield is a smooth panel support structure coupled with the surrounding rock of the tunnel. The middle shield is located on one side of the rear shield and is equipped with a plurality of jacking jacks for pushing the entire shield device to move. The front shield and the middle shield are equipped with a plurality of excavation devices for driving the tunnel soil on the upper side of the inclined surface. A support system is formed by the front shield, the middle shield, and the rear shield. The inclined surface pushes against the face. When the face is excavated, the front shield supports the soil to protect the construction safety. When the tunnel is excavated, the soil is discharged from the face, and the soil discharge is convenient and fast. At the same time, the shield follows the jacking and the arch frame or pipe segment is installed in the rear shield, so that the tunnel construction work is always carried out under the protection of the scaffolding, the shield and the pipe segment.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, and in particular to a mobile shield device and method for full-section excavation of a soft rock tunnel. Background Art

[0002] In the construction of medium and short length soft rock tunnels, in order to ensure the stability of the surrounding rock, large pipe shed advance support, small pipe advance support, grouting reinforcement, short step step excavation or CD method, CRD method, double side wall pilot method and other small section excavation + temporary support and expansion technology are adopted. The single cycle excavation section is small, it is difficult to use mechanized operation, and the temporary reinforcement workload is large, the efficiency is not high, and the safety risk is still high. For this reason, some long tunnels are now beginning to promote the highly efficient and safe fully mechanized rock tunnel boring machines (TBMs). This technology is more suitable for circular section tunnels with medium or lower rock strength. However, the economic section of traffic tunnels is horseshoe-shaped, especially many tunnels pass through soft and hard rocks, with large strength changes. The current TBM equipment has a very low excavation efficiency when encountering particularly hard rocks, which cannot meet the construction requirements and is difficult to switch in the middle. Due to the large workload of TBM equipment installation and disassembly, it is not economical for the construction of medium and short length tunnels. For medium and short length tunnels, tunnels with complex geological conditions such as soft and hard surrounding rocks, and non-circular cross-section rock tunnels, drilling and blasting construction is still more common. Researching a safe, efficient and fast drilling and blasting construction equipment and process for soft rock tunnels has always been the pursuit of the industry.

[0003] Chinese patent application document CN114876488A, published / announced on August 9, 2022, discloses a tunnel construction method and a shell-type tunnel boring machine. The method uses the cross-sectional contour line of the tunnel to be excavated as a reference, and first excavates the cross-sectional contour line part of the tunnel by excavation, and then uses manual, mechanical or blasting construction methods to excavate the remaining middle part of the tunnel in full section. The present invention first allows a shell-type tunnel boring machine to excavate a distance into the rock and soil body, and then the workers excavate in the shell, providing a safer working environment for the workers. The shell-type tunnel boring machine has over-excavation inside and outside the shell, allowing the surrounding rock to deform to a certain extent, giving full play to the self-stabilizing ability of the surrounding rock. Its characteristics are that the surrounding rock can be prevented from undergoing large deformation under the support of the shell, and the unexcavated soil in the shell is equivalent to the reserved core soil, which reduces the impact of tunnel excavation on the surrounding rock, reduces the settlement of the tunnel vault and the surrounding convergence, and reduces the impact of tunnel excavation on existing buildings on the ground. Its shortcomings are: first, the front end of the tunneling shell is covered with cutter discs. As long as one cutter disc is blocked by rock, the entire tunneling machine will not be able to work; second, the tunneling machine discharges soil through the soil transport pipes on both sides of the bottom. All the soil cut by the cutter discs needs to pass through the soil collection box and enter the soil collection pipe. Due to the complexity of the geological conditions, when stones enter the soil collection box, it will cause obstruction in the soil collection box, making the entire tunneling machine unable to work. Summary of the invention

[0004] A mobile shield device for full-section excavation of a soft rock tunnel comprises a front shield, a middle shield and a tail shield. The front shield is connected to the front of the middle shield, and the tail shield is connected to the rear of the middle shield. The middle shield is an annular closed structure matching the tunnel excavation profile and used to support the stability of the surrounding surrounding rock. Both sides of the front shield are provided with inclined surfaces inclined from the front end of the front shield to the middle shield. The tail shield is a smooth panel support structure coupled with the surrounding surrounding rock of the tunnel and used to install an arch frame or a pipe segment for initial support of the tunnel on its inner side. The middle shield is located on one side of the tail shield and is equipped with a plurality of jacking jacks for pushing the entire shield device to move. The front shield is equipped with a plurality of tunneling devices for setting up temporary scaffolding and cutting soil on the upper side of the inclined surface, and the front end of the tunneling device extends out of the front shield.

[0005] The middle shield comprises an arc-shaped top and a base, wherein the base is located at the lower side of the arc-shaped top, and two sides of the arc-shaped top extend along the tunnel excavation contour and are connected and fixed to two ends of the base.

[0006] The front shield includes a brim portion and a supporting portion, the supporting portion is connected to the two ends of the brim portion, the brim portion and the supporting portions on both sides are butted against the arc-shaped top of the middle shield, the inclined surface is arranged on the side of the supporting portion away from the middle shield, and is inclined from the front end of the brim portion toward the middle shield; the rear shield is an arc-shaped structure coupled with the tunnel excavation contour, and gaps are left between the two sides of the lower end of the arc-shaped structure and the base.

[0007] The tunneling device includes a drilling rig, a drill rod and a drilling rig push cylinder. The drilling rig is installed in the middle shield, one end of the drill rod is connected to the drilling rig, and the other end extends along the middle shield and the front shield and extends out of the front shield. The drilling rig push cylinder is installed on the other end of the drilling rig located at the drill rod. One end of the drilling rig push cylinder is supported at the tail of the middle shield, and the other end is connected to the drilling rig. The piston rod of the drilling rig push cylinder extends out to push the drilling rig and the drill rod. The rotation of the drilling rig drives the drill rod to drill into the soil of the tunnel face to form a grid-type scaffolding.

[0008] The front shield is located at the front end of the brim part and is equipped with a plurality of cutting discs for cutting soil. The cutting discs are driven by the drill rod to work.

[0009] A plurality of front machine seats are installed at the front end of the brim portion of the front shield, and a cutting disc is installed on the front machine seat. A through hole is provided in the center of the cutting disc, and a drill rod extends forward after passing through the through hole. A sleeve is mounted on the drill rod, and the rotation of the drill rod drives the sleeve to rotate at the same time. The sleeve and the cutting disc are driven by a key tooth structure matched with the inner wall of the through hole and the outer wall of the sleeve; the key tooth structure includes at least two first convex keys arranged on the inner wall of the through hole, and at least two second convex keys arranged on the outer wall of the sleeve, and the first convex keys and the second convex keys cooperate to form a meshing connection transmission.

[0010] The excavation device includes a serrated cutting steel plate, a sliding limit column is fixedly provided on the lower side of the serrated cutting steel plate, a sliding limit block is fixedly provided near the root of the serrations of the serrated cutting steel plate, the serrated cutting steel plate is installed on the upper side of the front end of the brim part of the front shield, the serrated cutting steel plate is fitted with the upper side surface of the brim part, the sliding limit column cooperates with the limiting slide groove on the upper side of the brim part, the sliding limit block abuts against the front end of the brim part, the bottom of the serrated cutting steel plate is respectively connected with one end of the steel cable near the two ends, the steel cable is installed in the brim part through a fixed pulley group, an eccentric disk is provided in the brim part, the other end of the steel cable is connected to the eccentric disk, when the eccentric disk rotates, the steel cables on both sides are pulled to reciprocate, thereby driving the serrated cutting steel plate at the front end of the brim part to swing back and forth in contact with the brim part.

[0011] The front shield, the arc-shaped top, and the tail shield are respectively connected by three curved panels through a first hinge structure, and the lower ends of the arc-shaped top are respectively connected to the two sides of the base through a second hinge structure. The base is provided with a telescopic structure that can be telescopically adjusted so that the base can adjust its width. Lifting masts for supporting the shield device structure are respectively provided on both sides of the base below the arc-shaped top.

[0012] A method for full-section excavation of a soft rock tunnel using a mobile shield device for full-section excavation of a soft rock tunnel comprises the following steps:

[0013] Step 1: First, dig a tunnel a certain distance as the starting tunnel or cast a supporting reaction wall at the tunnel entrance, and stabilize the tunnel face;

[0014] Step 2: Assemble the shields in the order of middle shield, tail shield, front shield, cutting disc and drill rod. After the assembly is completed, support the jacking jack on the support body embedded in the reaction wall or the inner wall of the tunnel, and push the shield device to press its front end against the tunnel excavation face;

[0015] Step 3: Start the drilling rig and drive the drill rod 4.5-5 meters into the unexcavated soil to form a grid-type scaffolding;

[0016] Step 4: Retract the drill rod 30-40cm so that the keyway on the drill rod coincides with the keyway on the sleeve, and then install the connecting key and secure it;

[0017] Step 5: Retract the drill rod and sleeve together to make the sleeve and the cutting disc cooperate for transmission;

[0018] Step 6: The cantilever excavation equipment excavates the tunnel face in front of the tunnel through the inner cavity of the shield device. At the same time, the drill rig drives the drill rod to drive the cutting disc to cut the unexcavated soil within the tunnel contour line and discharge the soil through the tunnel face. The jacking jack at the back pushes the shield to follow up and continue cutting the soil;

[0019] Step 7: After the shield device moves forward 30-40cm, stop pushing the shield device, start the drilling rig push cylinder behind the drilling rig to push the drill rod forward and continue to lay the pipe shed 40-50cm deep;

[0020] Step 8: Repeat Step 5 to 7. When the shield device moves forward in the tunnel to reach an arch frame or segment installation step, the jacking operation can be stopped, the jacking jack is retracted, the arch frame or segment is installed to reinforce the tunnel, and after the ring is formed, concrete spraying or backfill grouting construction is carried out, and the jacking jack is extended to press against one side of the arch frame or segment;

[0021] Step 9: Repeat steps 5 to 8 to complete tunnel excavation construction.

[0022] A method for full-section excavation of a soft rock tunnel using a mobile shield device for full-section excavation of a soft rock tunnel is provided.

[0023] When the sawtooth cutting steel plate is used, the jacking jack is supported on the support body pre-buried in the reaction wall or the inner wall of the tunnel, and the jacking shield device presses its front end against the tunnel face of the tunnel excavation. The cantilever excavation equipment excavates the tunnel face in front through the inner cavity of the shield. At the same time, the sawtooth cutting steel plate cuts the surrounding unexcavated soil and discharges the soil through the tunnel face. The jacking jack at the back pushes the shield to follow up.

[0024] When the cross-section changes, a tunnel with the length of the shield structure is excavated and supported by conventional excavation methods before the cross-section changes; Steps 5 to 9 are repeated, and after the shield device has fully entered the reinforced tunnel, the base is retracted through the telescopic structure, and the jacking mast is adjusted to close the side wall of the shield device, and then Steps 5 to 9 are repeated according to the new cross-section. The present invention has the following beneficial effects:

[0025] 1. The support system is formed by the front shield, middle shield and rear shield. The inclined surface is pressed against the tunnel face. When the tunnel face is excavated, the front shield supports the soil to protect the construction safety. The front shield is equipped with a tunneling device to facilitate the excavation of the top soil. When the tunnel is excavated, the soil is discharged from the tunnel face, and the soil discharge is convenient and fast. At the same time, the shield follows the top and the arch frame or pipe segment is installed in the rear shield, so that the tunnel construction work is always carried out under the protection of the scaffolding, shield and pipe segment.

[0026] 2. The brim is set to extend to the unexcavated area to provide safety protection for the bottom and facilitate the installation of the excavation device. The inclined surface cooperates with the heading face to make the tunnel excavated on a slope, which improves the safety of excavation.

[0027] 3. Drill rods are driven into the soil to form a grid-like scaffolding to provide protection for excavation below.

[0028] 4. The soil at the front end of the brim is cut by the cutting disc, which is convenient and quick, and solves the problem of inconvenience of manual upward construction and excavation. At the same time, the cutting disc is driven by the drill rod, no additional power is required, the structure is simple, and it is easy to use.

[0029] 5. The excavation device includes a serrated cutting steel plate, which is used to cut the soil at the front end of the brim of the serrated cutting steel plate as a whole.

[0030] 6. The front shield, the arc-shaped top, and the rear shield are respectively connected by three curved panels through a first hinge structure, and the lower ends of the arc-shaped top are respectively connected to the two sides of the base through a second hinge structure. The base is provided with a telescopic structure that can be telescopically adjusted, so that the base can adjust the width, so that the shield device of the present invention can be applied to different tunnel excavation sections, especially in a tunnel. The working conditions of using different tunnel excavation sections due to changes in the surrounding rock grade. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the main structural view of the present invention.

[0032] Figure 2 for Figure 1 Schematic diagram of the AA section structure.

[0033] Figure 3 for Figure 1 Schematic diagram of the BB cross-section structure.

[0034] Figure 4 for Figure 1 Schematic diagram of the CC cross-section structure.

[0035] Figure 5 This is a schematic diagram of the structure of the tunneling device installed in the present invention.

[0036] Figure 6 Schematic diagram of the three-dimensional structure of the present invention.

[0037] Figure 7 This is a structural schematic diagram of the drill rod of the present invention when it is ready to drill.

[0038] Figure 8 It is a schematic diagram of the structure of the present invention when the sleeve is mounted on the drill rod during drilling.

[0039] Fig. 9 It is a schematic diagram of the grid-type scaffolding structure formed when the drill rod of the present invention is drilled into place.

[0040] Fig.10 It is a structural schematic diagram of the present invention when the sleeve and the drill rod are fixed and the drill rod is retracted to make the sleeve and the cutting blade cooperate for transmission.

[0041] Fig.11The front shield, the arc-shaped top, and the tail shield of the present invention are respectively formed by hingedly connecting three curved panels.

[0042] Fig.12 It is a schematic diagram of the longitudinal structure of the cutting disc, drill rod and sleeve when they cooperate in transmission according to the present invention.

[0043] Fig.13 It is a schematic diagram of the connection structure between the drill rod and the sleeve of the present invention.

[0044] Fig.14 It is a schematic diagram of the structure of the through hole in the cutting disc of the present invention.

[0045] Fig.15 A schematic cross-sectional view of the cutting disc, drill rod and sleeve of the present invention when they cooperate in transmission.

[0046] Fig.16 Schematic diagram of the structure of the sawtooth cutting steel plate installed on the front shield of the present invention.

[0047] Fig.17 Fig.16 Schematic diagram of the DD section structure.

[0048] Fig.18 Schematic diagram of the cross-sectional structure of the sawtooth cutting steel plate of the present invention.

[0049] Fig.19 Schematic diagram of the unfolded structure of the sawtooth cutting steel plate of the present invention.

[0050] Fig. 20 A schematic diagram of the three-dimensional structure of the shield device of the present invention from a bottom perspective.

[0051] In the figure: front shield 1, brim portion 101, support portion 102, inclined surface 103, limiting slide groove 104, side pulley 105, middle pulley 106, middle shield 2, arc top 201, base 202, tail shield 3, notch 31, jacking jack 4, drilling rig 5, pipe segment 6, serrated cutting steel plate 7, sliding limiting column 71, sliding limiting block 72, steel cable 73, eccentric disc 8, drill rod 9, grid scaffolding 10, cutting disc 11, through hole 111, first convex key 112, face 12, unexcavated area 13, front machine base 14, sleeve 15, second convex key 151, drilling rig jacking cylinder 16, first hinged structure 17, second hinged structure 18, telescopic structure 19, jacking mast 20. DETAILED DESCRIPTION

[0052] The embodiments of the present invention are further described below in conjunction with the accompanying drawings.

[0053] Embodiment 1:

[0054] See also Figure 1-20A mobile shield device for full-section excavation of a soft rock tunnel comprises a front shield 1, a middle shield 2 and a tail shield 3, wherein the front shield 1 is connected to the front of the middle shield 2, and the tail shield 3 is connected to the rear of the middle shield 2, wherein the middle shield 2 is an annular closed structure matching the tunnel section and used to support the stability of the surrounding surrounding rock, and both sides of the front shield 1 are provided with inclined surfaces 103 inclined from the front end of the front shield 1 to the middle shield 2, and the tail shield 3 is a smooth panel support structure coupled with the surrounding surrounding rock of the tunnel, and is used to install an arch frame or a pipe segment 6 for tunnel support on its inner side, and the middle shield 2 is provided with 6-10 jacking jacks 4 for pushing the entire shield device to move on one side of the tail shield 3, and the front shield 1 and the middle shield 2 are provided with 10-20 excavation devices for setting up the tunnel soil on the upper side of the inclined surface 103, and the front end of the excavation device extends out of the front shield 1. The support system is formed by the front shield, the middle shield, and the rear shield. The inclined surface 103 pushes against the tunnel face 12. When the tunnel face 12 is excavated, the front shield 1 supports the soil to protect the construction safety. The front shield 1 is provided with a tunneling device to facilitate the excavation of the top soil. When the tunnel is excavated, the soil is discharged from the tunnel face, and the soil discharge is convenient and fast. At the same time, the shield follows the top-up and the arch frame or pipe segment is installed in the rear shield, so that the tunnel construction work is always carried out under the protection of the scaffolding, shield and pipe segment.

[0055] For details, see Figure 1 , 6 The middle shield 2 includes an arc-shaped top 201 and a base 202. The base 202 is located at the lower side of the arc-shaped top 201. The two ends of the base 202 are respectively connected and fixed to the two ends of the arc-shaped top 201. The base 202 is provided to provide support for the middle shield 2 and facilitate the passage of excavators and vehicles.

[0056] See also Figure 5 , 6 The front shield 1 includes a brim portion 101 and a support portion 102. The support portion 102 is connected to both ends of the brim portion 101. The brim portion 101 and the support portions 102 on both sides are connected to the arc-shaped top 201 of the middle shield 2. The inclined surface 103 is arranged on the side of the support portion 102 away from the middle shield 2, and is inclined from the front end of the brim portion 101 to the middle shield 2; the rear shield 3 is an arc-shaped structure matching the tunnel, and notches 31 are left on both sides of the lower end of the arc-shaped structure. The brim portion 101 is provided so as to extend toward the unexcavated area 13, provide safety protection for the lower part, and facilitate the installation of the excavation device. The inclined surface 103 cooperates with the face 12 to make the tunnel excavated on a slope, thereby improving the safety of the excavation.

[0057] See also Figure 7-10The excavation device includes a drilling rig 5, a drill rod 9 and a drilling rig top-pushing oil cylinder 16. The drilling rig 5 is installed in the middle shield 2 with a forward and backward sliding limit. One end of the drill rod 9 is connected to the drilling rig 5, and the other end extends along the middle shield 2 and the front shield 1 and extends out of the front shield 1. The drilling rig top-pushing oil cylinder 16 is installed at the other end of the drilling rig 5 located at the drill rod 9. One end of the drilling rig top-pushing oil cylinder 16 is connected to the middle shield 2, and the other end is connected to the drilling rig 5. The piston rod of the drilling rig top-pushing oil cylinder 16 extends to push the drilling rig 5 and the drill rod 9. The drill rod 9 drives the soil toward the tunnel face 12 to form a grid-type scaffolding 10. The grid-type scaffolding 10 is formed by driving the drill rod 9 into the soil to provide protection for the excavation below. When in use, the middle shield 2 is provided with an axial slide groove, and the drilling rig 5 is installed in the slide groove. The body of the drilling rig 5 is restricted from rotating and can only slide forward and backward.

[0058] See also Figure 5 , 6 The front shield 1 is located at the front end of the brim 101 and is rotatably mounted with a plurality of cutting discs 11 for cutting soil, and the cutting discs 11 are driven to rotate by the drill rod 9. The soil at the front end of the brim 101 is cut by the cutting discs 11, which is convenient and quick, and solves the problem of inconvenience of manual excavation.

[0059] For details, see Figure 6 , 12 -15, a plurality of front machine bases 14 are installed at the front end of the brim portion 101 of the front shield 1, and the rear end of the cutting disc 11 is rotatably installed in the front machine base 14 through a bearing. A through hole 111 is provided in the center of the cutting disc 11, and the drill rod 9 extends forward after passing through the through hole 111. A sleeve 15 is mounted on the drill rod 9, and the rotation of the drill rod 9 drives the sleeve 15 to rotate at the same time. The sleeve 15 and the cutting disc 11 are transmitted through a key tooth structure in which the inner wall of the through hole 111 and the outer wall of the sleeve 15 cooperate. The key tooth structure can adopt a spline pair structure. Preferably, in order to facilitate the sleeve 15 on the drill rod 9 to easily enter the through hole 111 when the drill rod 9 is retracted, the key tooth structure includes at least two first convex keys 112 arranged on the inner wall of the through hole 111, and at least two second convex keys 151 arranged on the outer wall of the sleeve 15. The first convex keys 112 and the second convex keys 151 cooperate to form a meshing connection transmission.

[0060] Embodiment 2:

[0061] See also Figure 16-19The excavation device includes a serrated cutting steel plate 7, a sliding limit column 71 is fixedly provided on the lower side of the serrated cutting steel plate 7, a sliding limit block 72 is fixedly provided near the root of the serrations of the serrated cutting steel plate 7, the serrated cutting steel plate 7 is mounted on the upper side of the front end of the brim portion 101 of the front shield 1, the serrated cutting steel plate 7 is fitted with the upper side of the brim portion 101, the sliding limit column 71 is slidably matched with the limit slide groove 104 on the upper side of the brim portion 101, and the sliding limit block 72 is abutted against At the front end of the brim 101, the bottom of the sawtooth cutting steel plate 7 is connected to one end of the steel cable 73 near the two ends. The steel cable 73 is installed in the brim 101 through a fixed pulley set. An eccentric disc 8 is provided in the brim 101. The other end of the steel cable 73 is connected to the eccentric disc 8. When the eccentric disc 8 rotates, the steel cables 73 on both sides are pulled to expand and contract, thereby driving the sawtooth cutting steel plate 7 at the front end of the brim 101 to swing back and forth on the brim 101. Through the rotation of the eccentric disc 8, the steel cables 73 on both sides are pulled, thereby driving the sawtooth cutting steel plate 7 to swing back and forth on the brim 101 to cut the soil.

[0062] Specifically, side pulleys 105 are provided on the left and right sides of the brim 101, and middle pulleys 106 are provided above the two sides of the eccentric disc 8. After the steel cable 73 passes around the side pulleys 105 on both sides, it passes around from above the middle pulley 106, and then connects with the connecting piece on the eccentric disc 8. Further, a rotating hole is provided in the middle of the connecting piece, and fixing holes for fixing the steel wire 73 are provided on both sides of the connecting piece. The two steel cables 73 are fixed to the fixing holes respectively, and the connecting piece is installed on the eccentric shaft of the eccentric disc 8 through the rotating hole. The eccentric disc 8 can be driven to rotate by a motor reducer combination, or it can be driven to rotate by a hydraulic motor.

[0063] In practical applications, the sawtooth cutting steel plate 7 can be used alone or in conjunction with the drill rod 9 .

[0064] Embodiment three:

[0065] See also Figure 6 , 20 The front shield 1, the arc-shaped top 201, and the rear shield 3 are respectively connected by three curved plates through a first hinge structure 17, and the lower ends of the arc-shaped top 201 are respectively connected to the two sides of the base 202 through a second hinge structure 18. The base 202 is provided with a telescopic structure 19 that can be telescopically adjusted, so that the base 202 can adjust the width. The base 202 is provided with a lifting mast 20 for supporting the shield device structure on both sides below the arc-shaped top 201. The shield device of the present invention can be applied to different tunnel excavation sections, especially in the working conditions of having different tunnel excavation sections in one tunnel.

[0066] Specifically, a curved panel is provided at the top, and side curved panels are symmetrically provided on both sides of the top curved panel. The side curved panels on both sides are respectively hinged to the top curved panel through a first hinge structure 17, and the lower ends of the side curved panels on both sides are respectively hinged to the two sides of the base 202 through a second hinge structure 18. The telescopic structure 19 can be guided by a guide column and guide sleeve structure, and then telescoped by a cylinder support, or a double-headed screw and nut structure can be used for telescope. The jacking mast 20 is used to lift and lower the curved panel during deformation. When lifting, the width of the base is narrowed and the top curved panel is raised; when lowering, the width of the base is widened and the height of the top curved panel is lowered. The lifting and lowering of the jacking mast 20 is performed by a cylinder, and after the execution is completed, it is fixed with steel sections.

[0067] There is also a hydraulic station inside the shield device to provide power for each cylinder and hydraulic motor.

[0068] Embodiment 4:

[0069] See also Figure 7-10 A method for full-section excavation of a soft rock tunnel using a mobile shield device for full-section excavation of a soft rock tunnel comprises the following steps:

[0070] Step 1: First, dig a tunnel a certain distance as the starting tunnel or cast a supporting reaction wall at the tunnel entrance, and stabilize the tunnel face 12;

[0071] Step 2: assemble the shields in the order of the middle shield 2, the rear shield 3, the front shield 1, the cutting disc 11, and the drill rod 9. After the assembly is completed, support the jacking jack 4 on the support body pre-buried in the reaction wall or the inner wall of the tunnel, and push the shield device to press its front end against the tunnel excavation face 12;

[0072] Step 3: Start the drilling machine 5 and drive the drill rod 9 into the unexcavated soil for 4.5-5 meters to form a grid scaffolding 10;

[0073] Step 4: Retract the drill rod 9 by 30-40 cm so that the keyway on the drill rod 9 coincides with the keyway on the sleeve 15, and then install the connecting key and fix it.

[0074] Step 5: retract the drill rod 9 and the sleeve 15 together, so that the sleeve 15 and the cutting disc 11 cooperate in transmission;

[0075] Step 6: The cantilever excavation equipment excavates the tunnel face 12 in front of the tunnel through the inner cavity of the shield device. At the same time, the drill rig 5 drives the drill rod 9 to drive the cutting disc 11 to cut the surrounding unexcavated soil and discharge the soil through the tunnel face 12. The jacking jack 4 at the back pushes the shield to follow up.

[0076] Step 7: After the shield device moves forward 30-40 cm, stop pushing the shield device, start the drilling rig pushing cylinder 16 behind the drilling rig 5 to push the drill rod 9 forward and continue to drive the pipe shed 40-50 cm deep;

[0077] Step 8: Repeat Steps 5 to 7. When the shield device moves forward in the tunnel to a distance of 6 steps for installing an arch frame or a segment, the jacking operation can be stopped, the jacking jack 4 is retracted, the arch frame or the segment 6 is installed to reinforce the tunnel, and after the ring is formed, the concrete spraying or backfill grouting construction is carried out, and the jacking jack 4 is extended to press against one side of the arch frame or the segment 6;

[0078] Step 9: Repeat Step 5 to 8 to complete the tunnel excavation construction;

[0079] When the sawtooth cutting steel plate 7 is used, the jacking jack 4 is supported on the support body pre-buried in the reaction wall or the inner wall of the tunnel, and the shield pushing device presses its front end against the tunnel face 12 of the tunnel excavation. The cantilever excavation equipment excavates the tunnel face 12 in front of the tunnel through the inner cavity of the shield. At the same time, the sawtooth cutting steel plate 7 cuts the surrounding unexcavated soil and discharges soil through the tunnel face 12. The rear jacking jack 4 pushes the shield to follow up;

[0080] When a cross-section change is encountered, a tunnel with a length of the shield structure is excavated and supported by conventional excavation methods before the cross-section changes; Steps 5 to 9 are repeated, and after all the shield devices have entered the reinforced and supported tunnel, the base 202 is retracted through the telescopic structure 19, and the lifting mast 20 is adjusted to retract the side walls of the shield device, and then Steps 5 to 9 are repeated according to the new cross-section.

[0081] Compared with conventional soft rock tunnel construction, this method can reduce the internal temporary support, realize the full-section excavation of the tunnel, facilitate large-scale mechanical construction, and improve the safety of tunnel construction. At the same time, the mobile follow-up grid scaffolding can greatly reduce the workload of hole making and pipe scaffolding compared with conventional methods. When encountering surrounding rock with particularly good stability, the shield jacking can be suspended, and it can be continued when encountering weak and broken surrounding rock. It is more convenient and flexible than shield machine construction.

Claims

1. A mobile shield device for full-section excavation of soft rock tunnels, characterized in that: It comprises a front shield (1), a middle shield (2), and a rear shield (3), wherein the front shield (1) is connected to the front of the middle shield (2), and the rear shield (3) is connected to the rear of the middle shield (2); the middle shield (2) is an annular closed structure matching the tunnel excavation profile and used to support the surrounding rock for stability; both sides of the front shield (1) are provided with inclined surfaces (103) inclined from the front end of the front shield (1) toward the middle shield (2); the rear shield (3) is a smooth panel support structure coupled with the surrounding rock of the tunnel and used to install an arch frame or a pipe segment (6) for initial support of the tunnel on its inner side; the middle shield (2) is provided with a plurality of jacking jacks (4) for pushing the entire shield device to move on one side of the rear shield (3); the front shield (1) is provided with a plurality of excavation devices for setting up temporary scaffolding and cutting soil on the upper side of the inclined surface (103); the front end of the excavation device extends out of the front shield (1); The middle shield (2) comprises an arc-shaped top (201) and a base (202), wherein the base (202) is located at the lower side of the arc-shaped top (201), and two sides of the arc-shaped top (201) extend along the tunnel excavation contour and are connected and fixed to two ends of the base (202); The excavation device comprises a drilling rig (5), a drill rod (9) and a drilling rig top-pushing cylinder (16); the drilling rig (5) is installed in the middle shield (2); one end of the drill rod (9) is connected to the drilling rig (5); the other end extends along the middle shield (2) and the front shield (1) and extends out of the front shield (1); the drilling rig top-pushing cylinder (16) is installed at the other end of the drilling rig (5) located at the drill rod (9); one end of the drilling rig top-pushing cylinder (16) is supported at the rear of the middle shield (2) and the other end is connected to the drilling rig (5); the piston rod of the drilling rig top-pushing cylinder (16) extends to push the drilling rig (5) and the drill rod (9); the drilling rig (5) rotates to drive the drill rod (9) to drill into the soil of the tunnel face (12), forming a lattice scaffold (10); The excavation device comprises a sawtooth cutting steel plate (7), a sliding limit column (71) is fixedly provided on the lower side of the sawtooth cutting steel plate (7), a sliding limit block (72) is fixedly provided near the root of the saw teeth of the sawtooth cutting steel plate (7), the sawtooth cutting steel plate (7) is mounted on the upper side of the front end of the brim portion (101) of the front shield (1), the sawtooth cutting steel plate (7) is fitted with the upper side of the brim portion (101), the sliding limit column (71) cooperates with the limit slide groove (104) on the upper side of the brim portion (101), and the sliding limit block (72) abuts against the brim portion (101). At the front end of the brim portion (101), the bottom of the sawtooth cutting steel plate (7) is connected to one end of a steel cable (73) near both ends. The steel cable (73) is installed in the brim portion (101) through a fixed pulley block. An eccentric disk (8) is provided in the brim portion (101). The other end of the steel cable (73) is connected to the eccentric disk (8). When the eccentric disk (8) rotates, the steel cables (73) on both sides are pulled to expand and contract, thereby driving the sawtooth cutting steel plate (7) at the front end of the brim portion (101) to swing back and forth in contact with the brim portion (101).

2. A mobile shield device for full-section excavation of a soft rock tunnel according to claim 1, characterized in that: The front shield (1) comprises a brim portion (101) and a support portion (102), the support portion (102) being connected to both ends of the brim portion (101), the brim portion (101) and the support portions (102) on both sides being butted against the arc-shaped top portion (201) of the middle shield (2), the inclined surface (103) being arranged on a side of the support portion (102) away from the middle shield (2), and being inclined from the front end of the brim portion (101) toward the middle shield (2); the rear shield (3) being an arc-shaped structure coupled with a tunnel excavation contour, with gaps (31) being left between the two sides of the lower end of the arc-shaped structure and the base (202).

3. The mobile shield device for full-section excavation of a soft rock tunnel according to claim 2, characterized in that: The front shield (1) is provided with a plurality of cutting discs (11) for cutting soil at the front end of the brim portion (101), and the cutting discs (11) are driven by the drill rod (9) to work.

4. The mobile shield device for full-face excavation of a soft rock tunnel according to claim 2, characterized in that: A plurality of front machine bases (14) are mounted at the front end of the brim portion (101) of the front shield (1), and a cutting disc (11) is mounted on the front machine base (14). A through hole (111) is provided at the center of the cutting disc (11). The drill rod (9) passes through the through hole (111) and extends forward. A sleeve (15) is mounted on the drill rod (9). The rotation of the drill rod (9) drives the sleeve (15) to rotate. The sleeve (15) and the cutting disc (11) are driven by a key tooth structure in which the inner wall of the through hole (111) and the outer wall of the sleeve (15) are matched. The key tooth structure comprises at least two first convex keys (112) arranged on the inner wall of the through hole (111), and at least two second convex keys (151) arranged on the outer wall of the sleeve (15). The first convex keys (112) and the second convex keys (151) are matched to form a meshing connection transmission.

5. The mobile shield device for full-face excavation of a soft rock tunnel according to claim 4, characterized in that: The front shield (1), the arc-shaped top (201), and the rear shield (3) are respectively connected by three curved panels via a first hinge structure (17), and the lower ends of the arc-shaped top (201) are respectively connected to the two sides of the base (202) via a second hinge structure (18), the base (202) is provided with a telescopic structure (19) that can be telescopically adjusted, so that the base (202) can adjust the width, and lifting masts (20) for supporting the shield device structure are respectively provided on both sides of the base (202) below the arc-shaped top (201).

6. A method for full-section excavation of a soft rock tunnel using a mobile shield device for full-section excavation of a soft rock tunnel as claimed in claim 5, characterized in that: The following steps are involved: Step 1: First, dig a tunnel a certain distance as the starting tunnel or cast a supporting reaction wall at the tunnel entrance, and stabilize the tunnel face (12); Step 2: The shields are assembled in the order of the middle shield (2), the rear shield (3), the front shield (1), the cutting disc (11), and the drill rod (9). After the assembly is completed, the jacking jack (4) is supported on a support body pre-buried in the reaction wall or the inner wall of the tunnel, and the jacking shield device presses its front end against the tunnel excavation face (12); Step 3: Start the drilling machine (5) and drive the drill rod (9) 4.5-5 meters into the unexcavated soil to form a grid-type scaffolding (10); Step 4: The drill rod (9) is retracted 30-40 cm so that the keyway on the drill rod (9) coincides with the keyway on the sleeve (15), and the connecting key is installed and fixed; Step 5: retract the drill rod (9) and the sleeve (15) together, so that the sleeve (15) and the cutting disc (11) cooperate to drive; Step 6: The cantilever excavation equipment excavates the tunnel face (12) in front of the tunnel through the inner cavity of the shield device. At the same time, the drill rig (5) drives the drill rod (9) to drive the cutting disc (11) to cut the unexcavated soil within the tunnel contour line, and discharge the soil through the tunnel face (12). The rear jacking jack (4) pushes the shield to follow up and continue cutting the soil; Step 7: After the shield device moves forward 30-40 cm, the shield device is stopped from pushing, and the drilling rig pushing cylinder (16) behind the drilling rig (5) is started to push the drill rod (9) forward to continue to drive the pipe shed 40-50 cm deep; Step 8: Repeat Steps 5 to 7. When the shield device moves forward in the tunnel to a step distance for installing an arch frame or a segment (6), the jacking operation can be stopped, the jacking jack (4) is retracted, the arch frame or the segment (6) is installed to reinforce the tunnel, and after the ring is formed, concrete spraying or backfilling grouting construction is carried out, and the jacking jack (4) is extended to press against one side of the arch frame or the segment (6); Step 9: Repeat steps 5 to 8 to complete tunnel excavation construction.

7. The method for full-section excavation of a soft rock tunnel using a mobile shield device for full-section excavation of a soft rock tunnel according to claim 6, characterized in that: When the sawtooth cutting steel plate (7) is used, the jacking jack (4) is supported on a support body pre-buried in the reaction wall or the inner wall of the tunnel, and the jacking shield device presses its front end against the tunnel face (12) of the tunnel excavation. The cantilever excavation equipment excavates the tunnel face (12) in front of the tunnel through the inner cavity of the shield. At the same time, the sawtooth cutting steel plate (7) cuts the surrounding unexcavated soil and discharges the soil through the tunnel face (12). The rear jacking jack (4) pushes the shield to follow up. When a cross-section change is encountered, a tunnel with a length of the shield structure is excavated and supported by conventional excavation methods before the cross-section changes; Steps 5 to 9 are repeated, and after the shield device has completely entered the reinforced and supported tunnel, the base (202) is retracted through the telescopic structure (19), and the lifting mast (20) is adjusted to retract the side walls of the shield device, and then Steps 5 to 9 are repeated according to the new cross-section.

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