Small-diameter circular ultra-deep vertical shaft foundation pit large shield split launching method

Abstract

The invention discloses a small-diameter circular ultra-deep vertical shaft foundation pit large shield split launching method, which belongs to the technical field of water tunnel shield construction, and comprises the following steps: 1, determining a shield launching position; 2, prefabricating a negative ring duct piece and a special-shaped extension steel ring; 3, mounting a special-shaped extension steel ring and a counter-force frame; 4, checking and accepting the originating node; 5, shield launching tunneling is carried out, and a negative ring segment is synchronously installed; 6, after shield launching is completed, the negative ring duct piece is chiseled away; and 7, steel bars are welded on the arc-shaped steel plates, and tunnel portal steel bars are bound on the arc-shaped steel plates. The arc-shaped interface of the to-be-tunneled tunnel portal and the shield tunneling machine can be adjusted to be the starting face perpendicular to the axis of the shield tunneling machine, it is guaranteed that the shield tunneling machine rapidly and safely completes starting, meanwhile, the constructed tunnel portal and the starting shaft end wall can form a plane, and guarantee is provided for smooth operation of a later hydraulic structure; and meanwhile, the embedded tunnel portal can be conveniently constructed by utilizing the arc-shaped steel plate embedded by the negative ring duct piece, so that the cost increase caused by steel bar planting is avoided, and the anchoring effect is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of shield construction of water conveyance tunnels, and in particular relates to a large shield split starting method for a small-diameter circular ultra-deep vertical shaft foundation pit. Background Art

[0002] Urban water conservancy projects have begun to widely use shield methods to construct urban water tunnels, which have several major characteristics: deep burial, small construction space, high requirements for structure and surface deformation control, and unlike subway construction, stations can be used as starting wells. Since urban water tunnels do not have dedicated starting wells, circular water inlets are used as starting wells, so they often face the situation of narrow starting sites, making it difficult to carry out subsequent shield construction.

[0003] At present, some water diversion tunnels with narrow starting sites adopt the combination of mechanical excavation and shield construction, that is, mechanical excavation is first carried out to form a construction guide tunnel that can accommodate shield machine equipment, and then the shield is assembled and stepped down to complete the start. However, this construction method requires mechanical excavation of the guide tunnel, which poses a great risk when encountering poor geology in the city. If the conventional shield split start method is used for start, the arc-shaped excavation tunnel door intersects with the cutterhead, and the cutterhead of the shield machine has begun to cut the soil on one side, while the cutterhead on the other side has not yet cut the soil, causing uneven force on the soil. Especially when water and sand are gushing from the back of the soil, the rubber sheet of the curtain cannot work normally and cannot play a sealing role, resulting in a safety accident at the start.

[0004] In view of the above problems, there is an urgent need for a shield machine starting method suitable for a small-diameter circular starting shaft. Summary of the invention

[0005] The object of the present invention is to provide a method for starting a large shield machine in a small-diameter circular ultra-deep vertical shaft foundation pit, so as to solve the problems existing in the background technology.

[0006] The objective of the present invention is achieved through the following technical solutions: A method for starting a large shield machine in a small-diameter circular ultra-deep vertical shaft foundation pit, comprising the following steps: Step 1: Determine the starting position of the shield machine: simulate the starting position of the shield machine according to the size of the circular starting shaft, and use the total station to accurately locate the coordinates of the reaction frame of the starting segment; Step 2, prefabricate negative ring segments and special-shaped extension steel rings: the special-shaped extension steel rings are made according to the shape of the starting tunnel portal, and according to the starting position simulated in step 1, an arc steel plate consistent with the shape of the starting tunnel portal is embedded in the negative ring segments prefabricated at the starting location. The arc steel plate is 1 cm thick and is embedded at a location 50 cm from the negative ring segments entering the starting tunnel portal. Step 3, installing the special-shaped extension steel ring and the reaction frame: one side of the special-shaped steel ring is in close contact with the starting tunnel door, and the other side is perpendicular to the axis of the shield machine to ensure the sealing during the starting process, and the curtain rubber plate is installed on the special-shaped extension steel ring; Step 4: Acceptance of the originating node; Step 5: The shield machine starts excavation and installs the negative ring segments simultaneously; Step 6: After the shield is started, the negative ring segment is chiseled off to expose the arc-shaped steel plate embedded in step 2; Step 7: Weld steel bars on the arc-shaped steel plate and tie the portal steel bars to complete the construction of the portal ring beam. The completed portal is in the same plane as the end wall of the starting portal.

[0007] Furthermore, the special-shaped extension steel ring is a cylindrical structure with openings at both ends. The special-shaped extension steel ring has a small mileage end and a large mileage end along the axial direction. The small mileage end is circular, and the large mileage end is a special-shaped ellipse. The large mileage end is tightly attached to the end wall of the circular starting well, and a base is installed at the bottom of the special-shaped extension steel ring.

[0008] Furthermore, the special-shaped extension steel ring is made of Q235B low-carbon steel, the thickness of the special-shaped extension steel ring is 1 cm, 4 grouting holes are arranged above the middle of the special-shaped extension steel ring, and the extension section of the special-shaped extension steel ring is connected to the embedded steel ring of the starting tunnel portal by bolts.

[0009] Furthermore, two sets of guide rails are provided on the inner side of the starting tunnel door, and the positions of the guide rails are based on the corresponding positions of the extension of the starting frame slide rails.

[0010] Furthermore, step 3 also includes sub-steps 31 to 37: Sub-step 31: accurately locating the center line of the shield tunnel in the circular starting shaft; Sub-step 32: first hoist the lower semicircle of the special-shaped extension steel ring on the ground and lower it into the circular starting shaft, and translate it to the position of the starting tunnel door, the axis of the special-shaped extension steel ring coincides with the line center line of sub-step S31, the special-shaped extension steel ring is welded to the embedded steel ring of the starting tunnel door by segmented spot welding, and then the upper semicircle of the special-shaped extension steel ring is hoisted in sequence, the large mileage end of the special-shaped extension steel ring is directly connected to the embedded steel ring of the starting tunnel door, and the small mileage end of the special-shaped extension steel ring is connected to the sealing device at the front end of the starting tunnel door through a flange; Sub-step 33: After the special-shaped extension steel ring is hoisted, the connecting bolts are tightened in sequence, checked and re-tightened, and the cylinder position of the special-shaped extension steel ring is re-measured to check whether it coincides with the center line of the shield machine; Sub-step 34: The cylinder of the special-shaped extended steel ring is welded into a whole through an arc-shaped plate; Sub-step 35: diagonal braces are provided on the left and right sides and the bottom of the cylinder of the special-shaped extended steel ring; Sub-step 36: installing the reaction frame, wherein the reaction frame comprises a portal support ring and a reaction ring; Sub-step 37: Install the starting bracket, which is a prefabricated steel structure, connected by a steel plate embedded in the concrete base plate, arranged in the direction of the line centerline, and tilted and fixed according to the slope that the cutter head end of the shield machine is 2 cm higher than the shield tail end of the shield machine.

[0011] Furthermore, in step 6, the negative ring segments are removed by combining mechanical and manual chiseling to chisel out the negative ring segments within 50 cm outside and inside the end wall of the starting tunnel portal.

[0012] The beneficial effects of the present invention are: 1) The present invention can adjust the arc-shaped interface between the tunnel portal to be excavated and the shield machine into a starting plane perpendicular to the axis of the shield machine, ensuring that the shield machine can start quickly and safely. At the same time, the tunnel portal after construction can form a plane with the end wall of the starting shaft, providing guarantee for the smooth operation of the hydraulic structure in the later stage.

[0013] 2) A special-shaped extension steel ring is installed at the starting tunnel gate, so that the starting cutting face of the shield machine can be adjusted to a vertical plane perpendicular to the center of the line to be excavated. There is no need to excavate the starting guide tunnel, which improves construction efficiency and ensures the safety of the start.

[0014] 3) At the same time, the arc-shaped steel plates embedded in the negative ring segments can be used to easily construct embedded portals, avoiding the increase in costs caused by embedded reinforcement, and the anchoring effect of welded steel bars is far better than that of embedded reinforcement.

[0015] 4) The present invention also adds reinforced stable structures such as inclined supports and bases to the special-shaped extension steel ring, optimizes the installation steps after installing the special-shaped extension steel ring, further ensures the sealing structure between the tunnel door and the special-shaped extension steel ring, and the sealing structure between the special-shaped extension steel ring and the shield shell of the shield machine, to ensure the smooth start of the shield. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flow chart of a method for starting a large shield machine separately in a small-diameter circular ultra-deep vertical shaft foundation pit according to the present invention; Figure 2 It is a structural schematic diagram of the present invention; In the figure, 1-circular launching shaft, 2-special-shaped extended steel ring, 3-negative ring segment, 4-launching tunnel portal, 5-curtain rubber sheet. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0018] See also Figure 1-Figure 2 , the present invention provides a technical solution: like Figure 1-Figure 2 As shown, a method for starting a large shield machine separately in a small-diameter circular ultra-deep vertical shaft foundation pit comprises the following steps: Step 1, determine the starting position of the shield machine: simulate the starting position of the shield machine according to the size of the circular starting shaft 1, and use the total station to accurately locate the coordinates of the reaction frame of the starting segment; Step 2, prefabricate the negative ring segment 3 and the special-shaped extension steel ring 2: the special-shaped extension steel ring 2 is made according to the shape of the starting tunnel portal, and an arc steel plate with the same shape as the starting tunnel portal 4 is embedded in the negative ring segment 3 prefabricated at the starting location simulated in step 1. The arc steel plate is 1 cm thick and the embedded position is 50 cm from the negative ring segment 3 into the starting tunnel portal; Step 3, installing the special-shaped extension steel ring 2 and the reaction frame: one side of the special-shaped steel ring is in close contact with the starting tunnel door 4, and the other side is perpendicular to the axis of the shield machine to ensure the sealing during the starting process, and the curtain rubber plate 5 is installed on the special-shaped extension steel ring 2; Step 4: Acceptance of the starting node: Attitude control is extremely important when the shield machine starts (arrives), and measurement and positioning work should be carried out in accordance with relevant technical requirements.

[0019] Step 5: The shield machine starts excavation and simultaneously installs the negative ring segment 3; Step 6: After the shield is started, the negative ring segment 3 is chiseled off to expose the arc-shaped steel plate embedded in step 2; Step 7: Weld steel bars on the arc-shaped steel plate and tie the portal steel bars to complete the construction of the portal ring beam. The completed portal is in the same plane as the end wall of the starting portal 4.

[0020] Through the above technical scheme, under the working condition of a small-diameter circular starting shaft 1, the present invention installs a special-shaped extended steel ring 2 on the starting tunnel portal 4, so that the starting cutting face of the shield machine can be adjusted to a vertical plane perpendicular to the center of the line to be excavated, without the need to excavate a starting guide tunnel, thereby improving the construction efficiency, ensuring the safety of the start, and avoiding the situation where the shield machine cutter head can only cut the arc-shaped face at the start, causing water and sand gushing, and the sealing structure of the shield machine cannot be guaranteed, causing safety accidents.

[0021] At the same time, the arc-shaped steel plate pre-buried in the negative ring segment 3 can be conveniently used to construct an embedded tunnel door, avoiding the increase in cost caused by planting reinforcement, and the anchoring effect of welded steel bars is far better than that of planting reinforcement.

[0022] The present invention also adds inclined supports, a base and other reinforced stable structures to the special-shaped extension steel ring 2, optimizes the installation steps after installing the special-shaped extension steel ring 2, further ensures the sealing structure between the tunnel door and the special-shaped extension steel ring 2, and the sealing structure between the special-shaped extension steel ring 2 and the shield shell of the shield machine, to ensure the smooth start of the shield.

[0023] The shield machine starting method based on the special-shaped extended steel ring 2 described in the present invention realizes the smooth starting of the shield machine by installing the special-shaped extended steel ring 2 even when a circular shaft is inconvenient to construct a starting guide tunnel, thereby laying a foundation for water conservancy project construction in areas with more complex working conditions and routes.

[0024] Furthermore, the special-shaped extension steel ring 2 is a cylindrical structure with openings at both ends, and the special-shaped extension steel ring 2 has a small mileage end and a large mileage end along the axial direction, the small mileage end is circular, and the large mileage end is a special-shaped ellipse, and the large mileage end is tightly attached to the end wall of the circular starting well 1, and a base is installed at the bottom of the special-shaped extension steel ring 2, wherein the base is used to support the cylindrical structure of the special-shaped extension steel ring 2.

[0025] Through the above technical solution, the special-shaped extended steel ring plays a role in supporting and stabilizing the excavation surface. When the shield machine moves forward, the special-shaped extended steel ring can ensure the flatness and stability of the excavation surface, prevent soil collapse, and ensure the smooth progress of tunnel excavation.

[0026] Furthermore, the special-shaped extension steel ring 2 is made of Q235B low-carbon steel, the thickness of the special-shaped extension steel ring 2 is 1 cm, 4 grouting holes are arranged above the middle of the special-shaped extension steel ring 2, and the extended section of the special-shaped extension steel ring 2 is connected to the embedded steel ring of the starting tunnel gate 4 by bolts.

[0027] Furthermore, two sets of guide rails are provided on the inner side of the starting tunnel door 4, and the positions of the guide rails are based on the corresponding positions of the extending slide rails of the starting frame.

[0028] Through the above technical solution, the waterproof device of the starting tunnel gate 4 includes a curtain rubber plate 5, a rubber ring and a folding pressure plate, which are connected by bolts with a diameter of 22mm. During the starting process of the shield machine, to prevent the shield machine cutter head from sinking, two sets of double-jointed guide rails are laid on the inner side of the tunnel gate steel ring. The guide rails are made of 43kg / m steel rails, 12cm long, and welded close to the edge of the circular ring plate of the tunnel gate steel ring. The elevation is slightly lower than the height of the starting support rail by 1cm. The length must not damage the sealing of the starting tunnel gate 4, and it must be welded firmly to prevent it from being damaged during the excavation of the shield machine, which affects the normal excavation of the shield. The position of the guide rail shall be based on the corresponding position of the extension of the starting frame slide rail. Furthermore, step 3 also includes sub-steps 31 to 37: Sub-step 31: accurately locating the center line of the shield tunnel in the circular starting shaft 1; Sub-step 32: First, hoist the lower semicircle of the special-shaped extension steel ring 2 on the ground and lower it into the circular starting shaft 1, and translate it to the position of the starting tunnel gate 4. The axis of the special-shaped extension steel ring 2 coincides with the line center line of sub-step S31. The special-shaped extension steel ring 2 is welded to the embedded steel ring of the starting tunnel gate 4 by segmented spot welding, and then the upper semicircle of the special-shaped extension steel ring 2 is hoisted in turn. The large mileage end of the special-shaped extension steel ring 2 is directly connected to the embedded steel ring of the starting tunnel gate 4, and the small mileage end of the special-shaped extension steel ring 2 is connected to the sealing device at the front end of the starting tunnel gate 4 through a flange. After the installation is completed, first install the curtain rubber plate 5, and then install the folding pressure plate.

[0029] Sub-step 33: After the special-shaped extension steel ring 2 is hoisted, the connecting bolts are tightened in sequence, checked and re-tightened, and the cylinder position of the special-shaped extension steel ring 2 is re-measured to check whether it coincides with the center line of the shield machine; Sub-step 34: The cylinder of the special-shaped extended steel ring 2 is welded as a whole through an arc-shaped plate; Sub-step 35: diagonal braces are provided on the left and right sides and the bottom of the cylinder of the special-shaped extension steel ring 2; wherein the diagonal braces are made of HW200×200 steel, and the spacing between adjacent diagonal braces is 1m, which is used to reinforce the special-shaped extension steel ring 2 to prevent the steel ring from shifting when the shield machine is excavating; Sub-step 36: Install the reaction frame, where the reaction frame is 1.8m thick and consists of a reaction ring and a support ring, which are connected by bolts and welding. The steel structure is welded with HM200×200 steel, the support ring is a door-type structure, and the upper and lower welded eight-shaped diagonal brace structures have an inner diameter of 10.5m; the reaction ring is a ring structure with an inner diameter of 10.5m.

[0030] Through the above technical solution, the installed reaction frame can not only bear the reverse force, but also constitute a stable structure of the shield machine, thereby ensuring the smooth operation of the shield machine during the excavation process.

[0031] Sub-step 37: Install the starting bracket, which is a prefabricated steel structure, connected by a steel plate embedded in the concrete base plate, arranged in the direction of the line centerline, and tilted and fixed according to the slope that the cutter head end of the shield machine is 2 cm higher than the shield tail end of the shield machine.

[0032] Through the above technical solution, the main function of the shield starting frame is to provide a stable and safe installation and trial excavation platform for the shield machine, ensuring the stability of the shield machine and the safety of construction.

[0033] At the same time, the starting frame provides the necessary reaction force for the shield machine's excavation through the reaction force frame, ensuring that the shield machine can advance stably during the excavation process.

[0034] Furthermore, the shield starting frame is equipped with guide rails to ensure that the shield machine can obtain correct guidance when it is pushed out of the tunnel, ensuring that the tunnel center, the tunnel entrance sealing center and the shield center are unified.

[0035] Furthermore, in step 6, the negative ring segments 3 are removed by combining mechanical and manual chiseling to chisel away the negative ring segments 3 within a range of 50 cm outside and inside the end wall of the starting tunnel portal 4.

[0036] Through the above technical solution, the negative ring segments are used as temporary support structures to ensure the stability and safety of the excavation process. After the initial work is completed, the negative ring segments are removed and used in subsequent tunnel construction.

[0037] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not depart from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A method for launching a large shield machine in a small-diameter circular ultra-deep vertical shaft foundation pit, characterized in that: The following steps are involved: Step 1, determine the starting position of the shield machine: simulate the starting position of the shield machine according to the size of the circular starting shaft (1), and use a total station to accurately locate the coordinates of the starting reaction frame; Step 2, prefabricate the negative ring segment (3) and the special-shaped extension steel ring (2): the special-shaped extension steel ring (2) is made according to the shape of the starting tunnel portal, and according to the starting position simulated in step 1, a curved steel plate having the same shape as the starting tunnel portal (4) is embedded in the negative ring segment (3) prefabricated at the starting location, the curved steel plate is 1 cm thick, and the embedded position is 50 cm from the negative ring segment (3) entering the starting tunnel portal (4); Step 3, installing the special-shaped extension steel ring (2) and the reaction frame: one side of the special-shaped steel ring is in close contact with the starting tunnel door (4), and the other side is perpendicular to the axis of the shield machine to ensure the sealing during the starting process, and the curtain rubber plate (5) is installed on the special-shaped extension steel ring (2); Step 4: Acceptance of the originating node; Step 5: The shield machine starts excavation and simultaneously installs the negative ring segments (3); Step 6: After the shield is started, the negative ring segment (3) is chiseled out to expose the arc-shaped steel plate embedded in step 2; Step 7: Weld steel bars on the arc-shaped steel plate and tie the portal steel bars to complete the construction of the portal ring beam. The completed portal is in the same plane as the end wall of the starting portal (4).

2. The method for launching a large shield machine in a small-diameter circular ultra-deep vertical shaft foundation pit according to claim 1 is characterized in that: The special-shaped extension steel ring (2) is a cylindrical structure with two ends open. The special-shaped extension steel ring (2) has a small mileage end and a large mileage end in the axial direction. The small mileage end is circular, and the large mileage end is a special-shaped ellipse. The large mileage end is closely attached to the end wall of the circular starting shaft (1). A base is installed at the bottom of the special-shaped extension steel ring (2).

3. The method for launching a large shield machine in a small-diameter circular ultra-deep vertical shaft foundation pit according to claim 1 is characterized in that: The special-shaped extension steel ring (2) is made of Q235B low-carbon steel, the thickness of the special-shaped extension steel ring (2) is 1 cm, four grouting holes are arranged above the middle of the special-shaped extension steel ring (2), and the extension section of the special-shaped extension steel ring (2) is connected to the embedded steel ring of the starting tunnel door (4) by bolts.

4. The method for launching a large shield machine in a small-diameter circular ultra-deep vertical shaft foundation pit according to claim 1 is characterized in that: Two sets of guide rails are arranged on the inner side of the launching tunnel door (4), and the positions of the guide rails are based on the corresponding positions of the extending slide rails of the launching frame.

5. The method for launching a large shield machine in a small-diameter circular ultra-deep vertical shaft foundation pit according to claim 2 is characterized in that: Step 3 also includes sub-steps 31 to 37: Sub-step 31: accurately locating the center line of the shield tunnel in the circular starting shaft (1); Sub-step 32: On the ground, first, hoist the lower semicircle of the special-shaped extension steel ring (2) and lower it into the circular starting shaft (1), and translate it to the position of the starting tunnel door (4), the axis of the special-shaped extension steel ring (2) coincides with the line center line of sub-step S31, the special-shaped extension steel ring (2) is welded to the embedded steel ring of the starting tunnel door (4) by segmented spot welding, and then the upper semicircle of the special-shaped extension steel ring (2) is hoisted in sequence, the large mileage end of the special-shaped extension steel ring (2) is directly connected to the embedded steel ring of the starting tunnel door (4), and the small mileage end of the special-shaped extension steel ring (2) is connected to the sealing device at the front end of the starting tunnel door (4) through a flange; Sub-step 33: After the special-shaped extension steel ring (2) is hoisted, the connecting bolts are tightened in sequence, checked and re-tightened, and the cylinder position of the special-shaped extension steel ring (2) is re-measured to check whether it coincides with the center line of the shield machine; Sub-step 34: the cylinder of the special-shaped extended steel ring (2) is welded into a whole through an arc-shaped plate; Sub-step 35: diagonal braces are provided on the left and right sides and the bottom of the cylinder of the special-shaped extension steel ring (2); Sub-step 36: installing the reaction frame, wherein the reaction frame comprises a portal support ring and a reaction ring; Sub-step 37: Install the starting bracket, which is a prefabricated steel structure, connected by a steel plate embedded in the concrete base plate, arranged in the direction of the line centerline, and tilted and fixed according to the slope that the cutter head end of the shield machine is 2 cm higher than the shield tail end of the shield machine.

6. The method for launching a large shield machine in a small-diameter circular ultra-deep vertical shaft foundation pit according to claim 1 is characterized in that: In step 6, the negative ring segments (3) are removed by combining mechanical and manual chiseling, and the negative ring segments (3) within a range of 50 cm outside and inside the end wall of the starting tunnel portal (4) are chiseled away.

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