Integral high-altitude hollow plate circular shield construction method

Abstract

The invention relates to the technical field of tunnel engineering, and particularly discloses an integral high-altitude hollow plate circular shield construction method which is characterized in that multiple improvements are made on the basis of an existing shield construction method, a circular shield tunnel is adopted to replace an original rectangular pipe jacking tunnel, dependence on advanced treatment of bedrock protrusions is reduced, and road occupation construction is avoided; a reserved pit slot is formed in a middle plate, a modularized launching platform is constructed, permanent and temporary combination is achieved, and material waste and construction period investment of construction of a temporary middle plate and an all-round scaffold are omitted while launching counter force is stably borne; the scheme of split starting and whole-course split tunneling is adopted, two times of hoisting construction of a bridge and a trolley going into a well and going out of the well are omitted, and the method can adapt to complex construction conditions of starting in a narrow space, receiving in a limited site, short tunnels, underneath passing of important roads and the like.

Description

Technical Field

[0001] The present invention relates to the field of tunnel engineering, and more specifically, to a method for constructing an integral high-altitude circular shield. Background Art

[0002] With the acceleration of urbanization, the scale of subway construction is constantly expanding, and factors such as stratum conditions, underground space environment, and ground sites have put forward higher and higher requirements on the technology and economy of subway construction. For example, the construction space in subway stations is limited, making it difficult to place tunneling equipment and its supporting systems at the same time; in the starting shaft, the tunneling equipment is heavy and the starting reaction force is large, so it is necessary to set up a full-height scaffolding or even construct a temporary middle plate as the shield starting platform, which takes a long time to build and affects the construction period; the receiving shaft is limited in width, and it is impossible to hoist the shield mainframe or trolley as a whole.

[0003] Under the complex surrounding environment of the city, affected by the demolition of ground buildings (structures), the relocation of underground municipal pipelines, and the diversion of ground traffic, it is often difficult for the stations for initial excavation to provide suitable site space and starting shaft width. Among many subway construction scenarios, the initial excavation of subway crossings is more difficult, especially the problem of bedrock protrusions invading tunnels. The first reason is that the ground traffic volume is larger and the road cannot be occupied for construction. The vertical treatment of the ground needs to avoid pipelines, leaving blind spots. Therefore, the bedrock protrusions are difficult to handle vertically on the ground; second, it is difficult to handle horizontally. When the rock formation strength is high, the horizontal treatment posture and direction are difficult to control; third, both treatment methods have the risk of secondary disturbance during the excavation of the pipe jacking machine after the formation is disturbed.

[0004] In the current subway station construction, rectangular pipe jacking machines are mainly used for excavation construction of entrance and exit crossings. Rectangular pipe jacking machines are limited by the shape of the cutterhead. There are inevitably a certain degree of excavation blind spots at the four corners of the rectangle during the excavation process. When encountering harder rock formations, it may be difficult to control the excavation deviation by relying solely on the thrust of the pipe jacking machine itself, and it may even cause serious consequences such as the cylinder getting stuck and the equipment being trapped. Summary of the invention

[0005] The present invention aims to overcome at least one of the deficiencies of the above-mentioned prior arts and provide an integral high-altitude intermediate plate circular shield construction method, which can effectively utilize the construction site and underground space, eliminate the rock formation processing steps, reduce the excavation blind area, and thus replace the existing rectangular pipe jacking machine solution; it can also simplify the construction of the shield starting platform, reduce the excavation construction risk of the subway station, and shorten the construction period.

[0006] The technical solution adopted by the present invention is to provide an integral high-altitude plate circular shield construction method, comprising the following steps: S1. Arrange the construction site and construct the starting well. A reserved pit is set on the lower middle plate in the starting well; S2. Hoisting the construction materials into the starting shaft through the reserved pit to construct a high-altitude plate shield starting platform; S3, hoist the components of the shield machine into the starting shaft, assemble the shield machine, assemble the bridge and trolley on the ground and connect the bridge and trolley to the shield machine through pipelines, debug the shield machine, and install the negative ring segments; S4, split start, the whole process adopts split excavation, and the connection between the shield machine and the bridge and trolley is ensured by extending the pipeline; S5. Install the shield receiving bracket, receive the shield machine out of the hole, and hoist the shield host out of the receiving shaft; S6. Dismantle the starting platform of the high-altitude middle plate shield, backfill the reserved pit of the lower middle plate, and reconstruct the upper middle plate.

[0007] The invention provides an integral high-altitude circular shield construction system and method, which makes the following improvements on the basis of the existing shield construction method. First, a circular shield tunnel is used to replace the original rectangular jacking tunnel to reduce the excavation blind area, reduce the reliance on the advance treatment of bedrock protrusions, and avoid road construction. Secondly, the entire middle plate in the starting shaft is not removed, but the majority of the structure of the lower middle plate is retained, and only a reserved pit with a length less than the starting frame and a width less than the diameter of the shield machine is dug out to build a modular starting platform, realizing the combination of permanent and temporary, that is, the permanent structure middle plate and the temporary structure steel platform jointly bear the load and stably bear the starting reaction force; at the same time, the material waste and construction period investment of the temporary middle plate and the full-house scaffolding are saved; the pit design also simplifies the subsequent shield machine installation steps and avoids repeated adjustment of the middle plate structure. Finally, the split starting and full-process split excavation scheme is adopted, which saves the bridge frame and the trolley from going down and out of the well twice. The hoisting construction can adapt to the complex construction conditions such as narrow space starting, limited site reception, short tunnels, and crossing important roads.

[0008] Furthermore, the distance between the starting well and the receiving well is no more than twice the total length of the trolley. In the embodiment of excavating the street crossing tunnel, the present invention adopts a split starting and full split excavation scheme, which avoids the two hoisting constructions of the bridge frame and the trolley into and out of the well, which not only reduces the downtime waiting time of the shield machine in the process of passing through important roads, reduces the construction risk, but also shortens the construction period by about 5 days, and is suitable for short tunnel excavation. The scheme also solves the problem of limited internal space of the station, and can adapt to the shield starting and excavation in the narrow station space, as well as the shield receiving in the limited ground space. Taking the street crossing of the urban rail transit station as an example, on the one hand, its receiving well is small in size, and it is difficult to hoist the trolley out. On the other hand, the overall length of the street crossing is limited, which can neither accommodate multiple trolleys nor bring about the side effect of reduced pumping pressure due to excessive pipeline length. Therefore, it is suitable to adopt the split starting and full split excavation scheme.

[0009] Furthermore, the width of the receiving well is smaller than the length of the trolley. When the width of the receiving well is smaller than the length of the trolley, if the trolley enters the starting well and follows the main shield machine, it cannot be hoisted out of the receiving well and still needs to be towed back to the starting well and hoisted out, which slows down the construction period. Therefore, when the width of the receiving well is small, it is suitable to adopt the split starting and full split excavation scheme.

[0010] Furthermore, the long side of the reserved pit is provided with a tongue, and the tongue is provided with a first rail for supporting the shield machine. The reserved pit matches the size of the shield machine, and the tongue and the rail provide a stable guide, which provides stable support for the shield machine on the one hand, and reduces the risk of deviation when the shield machine is started on the other hand.

[0011] Furthermore, when multiple tunnels are excavated at the lower middle plate height, step S1 needs to open multiple corresponding reserved pits, and step S4 starts the shield machine alone in a reserved pit, while temporary supports are set horizontally in other reserved pits.

[0012] Furthermore, when digging multiple tunnels in the same direction, the shield machines of different tunnels in step S4 can dig simultaneously at different progress rates.

[0013] Furthermore, in step S5, when the receiving well width is insufficient, the shield machine is disassembled in the receiving well and then hoisted out. When the width of the receiving well is less than the full length of the shield machine, after a part of the shield machine is out of the hole, the shield machine is disassembled in the receiving well and hoisted out separately, and the hoisting order is cutterhead, screw machine, front shield, middle shield and tail shield, among which the screw machine is disassembled and dragged back to the starting well for hoisting, and the others are hoisted out in the receiving well in sequence.

[0014] Furthermore, the high-altitude plate shield starting platform includes a starting frame and a reaction frame. The starting frame is fixed on the station bottom plate, the top of the starting frame is lower than the lower middle plate and is fixedly connected to the lower middle plate, and the reaction frame is arranged on the starting frame.

[0015] Furthermore, the reaction frame comprises: The steel ring is located on the side close to the shield machine and is used to directly withstand the impact of the shield tail of the shield machine; A rear shield frame is arranged at a side away from the shield machine and is fixedly connected to the steel ring; The first diagonal brace connects the structural beam of the backing frame and the upper middle plate; The second diagonal brace connects the backing frame and the lower middle plate.

[0016] Furthermore, the number of the second diagonal braces is greater than that of the first diagonal braces. More diagonal braces are arranged diagonally downward, thereby enhancing the support capacity of the heavy-load shield machine, balancing the force, and preventing the platform from tilting due to uneven vertical load.

[0017] Furthermore, the angles between the first diagonal brace and the second diagonal brace and the horizontal plane are 20° to 25°. The specific inclination angles optimize the horizontal force transfer efficiency. On the one hand, they effectively offset the frictional resistance during shield tunneling. On the other hand, they prevent the reaction frame from floating due to the reaction force of the diagonal braces.

[0018] Furthermore, the launching frame includes: Columns, with the lower ends connected to the floor slab of the station and the upper ends having a height lower than the lower middle plate; The third diagonal brace, used to connect adjacent columns; The plate layer, laid on the upper ends of the columns, with one side closely attached to the station structural beam under the launching portal; Multiple middle plate supports, located above the two columns on both sides of the shield direction, connected to the plate layer at the lower end and the lower middle plate at the upper end; The shield machine bracket, laid on the plate layer, under the launching portal, and between the two rows of middle plate supports. The second rail is provided on the shield machine bracket.

[0019] The above-mentioned launching frame disperses the shield machine load vertically to multiple columns and horizontally to the lower middle plate; the components adopt a modular design, which helps to simplify the on-site construction process. The middle plate supports are connected to the steel plate at the lower end and the lower middle plate at the upper end, realizing the permanent and temporary combination of the middle plate and the launching platform, jointly bearing the shield launching load, and being able to safely and stably support the shield launching. One side of the steel plate is closely attached to the station structural beam under the launching portal, avoiding the overall forward overturning of the launching platform caused by the forward frictional force during the shield launching process. The second rail provided on the shield machine bracket has a similar function to the first rail, providing stable guidance and reducing the deviation risk when the shield machine starts.

[0020] Furthermore, the connection methods of the columns, the third diagonal brace, the plate layer, the middle plate supports, and the shield machine bracket are welding connections. The welding connections ensure the structural integrity and reduce the safety risks.

[0021] Furthermore, the width-depth ratio of each weld of the welding connection should not be less than 1.1. Controlling the width-depth ratio avoids brittle fracture caused by too deep welds, enhances the welding reliability, and improves the structural fatigue resistance and impact resistance.

[0022] Furthermore, the plate layer includes an upper steel plate, a vertical and horizontal skeleton, and a lower steel plate that are fixedly connected in sequence from top to bottom. This is beneficial to improving the overall stiffness.

[0023] Furthermore, the vertical and horizontal skeleton includes longitudinal steel beams and transverse steel beams, and the intersections of the longitudinal steel beams and the transverse steel beams are all located above the columns. This conducts the pressure received by the upper steel plate more evenly to the lower steel plate, which is beneficial to reducing the risk of local deformation.

[0024] Furthermore, the middle plate support includes short steel pipes and / or multiple spliced I-beams, and the I-beams are connected above the short steel pipes. The assembly is simple and the structure is stable.

[0025] Furthermore, the number of the second diagonal braces is more than that of the first diagonal braces. There are more lower-layer diagonal braces, which enhances the supporting capacity for the heavy load of the shield machine, makes the force balanced, and prevents the platform from tilting due to uneven vertical loads.

[0026] Furthermore, the inclination angle of the first diagonal brace with the horizontal plane is 20 - 25°. The specific inclination angle optimizes the transmission efficiency of the horizontal component force. On the one hand, it effectively offsets the frictional resistance during shield propulsion. On the other hand, it prevents the reaction frame from floating up due to the reaction force of the diagonal brace.

[0027] The above-mentioned launching frame distributes the shield machine load to multiple columns in the vertical direction and to the lower middle plate in the horizontal direction; the components adopt modular design, which helps to simplify the on-site construction process. The middle plate support is connected to the steel plate at the bottom and the lower middle plate at the top, realizing the permanent and temporary combination of the middle plate and the launching platform, jointly bearing the shield launching load, and being able to safely and stably support the shield launching. One side of the steel plate is closely attached to the station structural beam under the launching portal, avoiding the overall forward overturning of the launching platform due to the forward frictional force during the shield launching process. The second rail set on the shield machine bracket has a similar function to the first rail, providing stable guidance and reducing the deviation risk when the shield machine starts. The welded connection ensures the structural integrity and reduces the safety risk.

[0028] Furthermore, the steel plate includes an upper steel plate, vertical and horizontal skeletons, and a lower steel plate that are fixedly connected in sequence from top to bottom. The design of the layered steel plate and the skeleton can improve the overall stiffness.

[0029] Furthermore, the intersections of the vertical and horizontal skeletons are all located above the columns. The pressure received by the upper steel plate is transmitted to the lower steel plate more evenly, which is beneficial to reducing the risk of local deformation.

[0030] Furthermore, the middle plate support includes short steel pipes and / or spliced I-beams. The assembly is simple and the structure is stable.

[0031] Furthermore, the width-depth ratio of each weld of the welded connection should not be less than 1.1. The control of the width-depth ratio avoids brittle fracture caused by too deep welds, enhances the welding reliability, and improves the fatigue resistance and impact resistance of the structure.

[0032] Furthermore, when excavating multiple tunnels at the height of the lower middle plate, multiple reserved pits need to be opened, and the shield main machine starts separately in a certain reserved pit; during the starting and tunneling process, steel pipes are horizontally arranged in other reserved pits as temporary supports.

[0033] Furthermore, in step S5, when the receiving well width is insufficient, after a portion of the shield machine is out of the hole, the shield machine is split in the receiving well and hoisted out separately. Splitting the shield machine when the receiving well width is insufficient solves the problem of insufficient hoisting space in the traditional solution.

[0034] Compared with the prior art, the present invention has the following beneficial effects: The invention provides an integral high-altitude middle plate circular shield construction method, which makes multiple improvements on the basis of the existing shield construction method. A circular shield tunnel is adopted to replace the original rectangular jacking tunnel, thereby reducing the reliance on advance treatment of bedrock protrusions and avoiding road occupation for construction. A reserved pit is opened in the middle plate to construct a modular starting platform, thereby realizing the combination of permanent and temporary. While stably bearing the starting reaction force, the material waste and construction period investment of the temporary middle plate and full-hall scaffolding are eliminated. A split starting and full-process split excavation scheme is adopted, thereby eliminating the two hoisting constructions of the bridge frame and the trolley for going down and out of the well, and can adapt to complex construction conditions such as starting in narrow space, receiving in limited site, short tunnel, and crossing important roads. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a longitudinal section view of the high-altitude plate shield starting platform provided in Example 1.

[0036] Figure 2 This is a cross-sectional view of the high-altitude plate shield starting platform provided in Example 1.

[0037] Figure 3 This is a partially enlarged cross-sectional view of the high-altitude plate shield starting platform provided in Example 1.

[0038] Figure 4 This is a top view of the vertical and horizontal skeletons above the columns of the high-altitude plate shield starting platform provided in Example 1.

[0039] Figure 5 This is a cross-sectional schematic diagram of the layout of the shield machine, bridge and trolley during the starting and excavation process of Example 1.

[0040] Figure 6 This is a schematic diagram of the temporary support for the right line pit when the left line starts.

[0041] Figure 7 This is the flow chart for hoisting the receiving shaft of the shield main machine. a. After the penultimate ring segment is assembled, the cutterhead is removed and hoisted out; b. Move forward 400mm, assemble the last ring segment, remove the screw machine in the tunnel and pull it back; c. Remove the front shield and hoist it out; d. Move the middle shield and the tail shield forward, disassemble and hoist them out.

[0042] Label description: bottom plate 110, lower middle plate 120, reserved pit 121, first rail 122, upper middle plate 130, starting portal 140, station structural beam 150, shield main machine 160, cutter head 161, front shield 162, middle shield 163, shield tail 164, screw conveyor 165, top plate 170, reaction frame 200, rear support frame 210, first diagonal brace 220, second diagonal brace 230, starting frame 300, column 310, third diagonal brace 320, plate layer 330, vertical and horizontal skeleton 331, middle plate support 340, short steel pipe 341, I-beam 342, shield machine bracket 350, second rail 351, temporary support 360. Pipeline 400, bridge and trolley 500. Detailed implementation mode

[0043] The attached drawings of the present invention are only for illustrative purposes and should not be construed as a limitation of the present invention. For better illustration of the following embodiments, some components in the attached drawings will be omitted, enlarged or reduced, which do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the attached drawings may be omitted. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. It should be noted that the terms used herein are only for describing the specific implementation mode and are not intended to limit the exemplary implementation mode according to this application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also 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 their combinations.

[0044] The present invention will be further described below in combination with specific examples. The following embodiments are only for explaining the present invention and do not constitute a limitation to the present invention. Tools, building materials, etc. used in the following embodiments can be obtained from commercial channels unless otherwise specified.

[0045] Embodiment 1 As Figures 1 to 7 shown, this embodiment provides a method for constructing a circular shield with an integral high-altitude middle plate, including the following steps: S1. Arrange the construction site, construct the starting shaft of the construction, and open a reserved pit 121 on the lower middle plate 120 according to the size of the shield machine; S2. Lift building materials into the starting shaft through the reserved pit 121 to construct a shield starting platform for the high-altitude middle plate; S3. Lift each component of the shield main machine 160 into the starting shaft, assemble the shield main machine 160, assemble the bridge and trolley 500 on the ground and connect the bridge and trolley 500 to the shield main machine 160 through the pipeline 400, debug the shield main machine 160, and install the negative ring segment; S4, split start, split excavation is adopted throughout the whole process, and the connection between the shield machine 160 and the bridge and the trolley is ensured by extending the pipeline 400; S5. Install the shield receiving bracket, receive the shield machine out of the hole, and hoist the shield main machine 160 out of the receiving well; S6. Dismantle the starting platform of the high-altitude middle plate shield, backfill the reserved pit 121 of the lower middle plate 120, and reconstruct the upper middle plate 130.

[0046] The present invention provides an integral high-altitude middle plate circular shield construction system and construction method, which makes the following improvements on the basis of the existing shield construction method. First, a circular shield tunnel is used to replace the original rectangular jacking tunnel to reduce the excavation blind area, reduce the reliance on the advance treatment of bedrock protrusions, and avoid road construction. Secondly, the entire middle plate in the starting shaft is not removed, but the majority of the structure of the lower middle plate 120 is retained, and only a reserved pit 121 with a length less than the starting frame 300 and a width less than the diameter of the shield machine is dug out to build a modular starting platform, realizing the combination of permanent and temporary, that is, the permanent structure middle plate and the temporary structure steel platform jointly bear the load and stably bear the starting reaction force; at the same time, it saves the material waste and construction period investment of the temporary middle plate and the full-hall scaffolding; the pit design also simplifies the subsequent shield machine installation steps and avoids repeated adjustments to the middle plate structure. Finally, a split-start and full-length split-excavation scheme was adopted, with the rear accessories placed on the top plate 170 throughout the entire process, eliminating the need for two hoisting operations of the bridge and trolley down and out of the well. It can adapt to complex construction conditions such as starting in narrow spaces, receiving in limited sites, short tunnels, and crossing important roads.

[0047] The distance between the starting well and the receiving well is no more than twice the total length of the trolley. In the embodiment of excavating the street crossing tunnel, the present invention adopts a split starting and full split excavation scheme, which avoids the two hoisting constructions of the bridge frame and the trolley into and out of the well, which not only reduces the downtime waiting time of the shield machine in the process of passing through important roads, reduces the construction risk, but also shortens the construction period by about 5 days, and is suitable for short tunnel excavation. The scheme also solves the problem of limited internal space of the station, and can adapt to the shield starting and excavation in the narrow station space, as well as the shield receiving in the limited ground space. Taking the street crossing of the urban rail transit station as an example, on the one hand, its receiving well is small in size, and it is difficult to hoist the trolley out. On the other hand, the overall length of the street crossing is limited, which can neither accommodate multiple trolleys nor bring the side effect of reduced pumping pressure due to excessive pipeline length. Therefore, it is suitable for the split starting and full split excavation scheme.

[0048] The width of the receiving well is smaller than the length of the trolley. When the width of the receiving well is smaller than the length of the trolley, if the trolley enters the starting well and follows the shield machine 160, it cannot be hoisted out of the receiving well and still needs to be towed back to the starting well and hoisted out, which slows down the construction period. Therefore, when the width of the receiving well is small, it is suitable to adopt the split starting and full split excavation scheme.

[0049] The long side of the reserved pit 121 is provided with a tongue and groove, and the tongue and groove is provided with a first rail 122 for supporting the shield mainframe 160. Figure 3 The reserved pit 121 matches the size of the shield machine, and the groove and the rail provide a stable guide, which not only provides a stable support for the shield machine, but also reduces the risk of deviation when the shield machine is started.

[0050] When digging multiple tunnels at a height of 120 in the lower middle plate, Figure 6 As shown, step S1 needs to open a corresponding plurality of reserved pits 121 , and step S4 the shield machine 160 starts alone in a certain reserved pit 121 , while temporary supports 360 are horizontally arranged in other reserved pits 121 .

[0051] When digging multiple tunnels in the same direction, the shield machines of different tunnels in step S4 can dig at different progress simultaneously.

[0052] In step S5, when the receiving well width is insufficient, the shield machine 160 is disassembled in the receiving well and then hoisted out. Figure 7 As shown, when the width of the receiving well is smaller than the full length of the shield main machine 160, after a part of the shield main machine 160 comes out of the hole, the shield main machine 160 is disassembled in the receiving well and hoisted out separately, and the order of hoisting out is the cutter head 161, the screw machine 165, the front shield 162, the middle shield 163 and the shield tail 164. Among them, the screw machine 165 is removed and then dragged back to the starting well for hoisting, and the others are hoisted out in the receiving well in sequence.

[0053] The high-altitude upper plate shield starting platform includes a starting frame 300 and a reaction frame 200. The starting frame 300 is fixed on the station bottom plate 110. The top of the starting frame 300 is lower than the lower middle plate 120 and is fixedly connected to the lower middle plate 120. The reaction frame 200 is arranged on the starting frame 300.

[0054] like Figure 1 As shown, the reaction frame 200 includes: The steel ring is arranged on the side close to the shield machine and is used to directly bear the impact of the shield tail 164 of the shield machine; The rear shield frame 210 is arranged at a side away from the shield machine and is fixedly connected to the steel ring; The first diagonal brace 220 is a structural beam connecting the backing frame 210 and the upper middle plate 130; The second diagonal brace 230 connects the backing frame 210 and the lower middle plate 120 .

[0055] The number of the second diagonal braces 230 is greater than the number of the first diagonal braces 220. More diagonal braces diagonally downward are provided to enhance the heavy-load support capability of the shield machine, balance the force, and prevent the platform from tilting due to uneven vertical load.

[0056] The included angles between the first diagonal brace 220 and the second diagonal brace 230 and the horizontal plane are 20° to 25°. The specific inclination angles optimize the horizontal component force transfer efficiency. On the one hand, it effectively offsets the frictional resistance during shield tunneling. On the other hand, it prevents the reaction frame 200 from floating due to the diagonal brace reaction force.

[0057] As Figure 2 and Figure 3 shown, the launching frame 300 includes: Columns 310, with the lower ends connected to the floor slab 110 of the station and the upper ends having a height lower than the lower middle plate 120; The third diagonal brace 320, used to connect adjacent columns 310; The plate layer 330, laid on the upper ends of the columns 310, with one side closely attached to the station structural beam 150 under the launching portal 140; A plurality of middle plate supports 340, located above two columns 310 on both sides of the shield direction, connected to the plate layer 330 at the lower end and the lower middle plate 120 at the upper end; The shield machine bracket 350, laid on the plate layer 330, under the launching portal 140, and between two rows of middle plate supports 340. The second rail 351 is provided on the shield machine bracket 350.

[0058] The above-mentioned launching frame 300 disperses the shield machine load vertically to multiple columns 310 and horizontally to the lower middle plate 120; the components adopt a modular design, which helps to simplify the on-site construction process. The middle plate support 340 is connected to the steel plate at the lower end and the lower middle plate 120 at the upper end, realizing the permanent and temporary combination of the middle plate and the launching platform, jointly bearing the shield launching load, and being able to safely and stably support the shield launching. One side of the steel plate is closely attached to the station structural beam 150 under the launching portal 140, avoiding the overall forward overturning of the launching platform caused by the forward frictional force during shield launching. The second rail 351 provided on the shield machine bracket 350 has a similar function to the first rail 122, providing stable guidance and reducing the deviation risk when the shield machine starts.

[0059] The connection methods of the columns 310, the third diagonal brace 320, the plate layer 330, the middle plate supports 340, and the shield machine bracket 350 are welded connections. The welded connections ensure the structural integrity and reduce the safety risk.

[0060] The width-depth ratio of each weld of the welded connection should not be less than 1.1. The control of the width-depth ratio avoids brittle fracture caused by too deep welds, enhances the welding reliability, and improves the fatigue resistance and impact resistance of the structure.

[0061] The plate layer 330 includes an upper steel plate, a vertical and horizontal skeleton 331, and a lower steel plate that are fixedly connected in sequence from top to bottom. It is beneficial to improve the overall stiffness.

[0062] The longitudinal and transverse frameworks 331 include longitudinal steel beams and transverse steel beams, and the intersections of the longitudinal steel beams and the transverse steel beams are all located above the columns 310. This conducts the pressure on the upper steel plate more evenly to the lower steel plate, which is beneficial to reducing the risk of local deformation.

[0063] The middle plate support 340 includes short steel pipes 341 and / or a plurality of spliced I-beams 342, and the I-beams 342 are connected above the short steel pipes 341. It is simple to assemble and has a stable structure.

[0064] The number of the second diagonal braces 230 is more than that of the first diagonal braces 220. There are more lower diagonal braces, which enhances the supporting ability for the heavy load of the shield machine, has balanced stress, and prevents the platform from tilting due to uneven vertical loads.

[0065] The inclination angle of the first diagonal brace 220 with the horizontal plane is 20 - 25°. The specific inclination angle optimizes the transmission efficiency of the horizontal component force. On the one hand, it effectively offsets the frictional resistance during shield tunneling. On the other hand, it prevents the reaction frame 200 from floating up due to the reaction force of the diagonal brace.

[0066] The above-mentioned starting frame 300 disperses the load of the shield machine vertically to multiple columns 310 and horizontally to the lower middle plate 120; the components are designed modularly, which helps to simplify the on-site construction process. The middle plate support 340 is connected to the steel plate at the bottom and the lower middle plate 120 at the top, realizing the permanent and temporary combination of the middle plate and the starting platform, jointly bearing the shield starting load, and being able to safely and stably support the shield starting. One side of the steel plate is closely attached to the station structural beam 150 under the starting portal 140, avoiding the overall forward overturning of the starting platform caused by the forward frictional force during shield starting. The second rail 351 provided on the shield machine bracket 350 has a similar function to the first rail 122, providing stable guidance and reducing the offset risk when the shield machine starts. Welded connections ensure the structural integrity and reduce safety risks.

[0067] The steel plate includes an upper steel plate, a longitudinal and transverse framework 331, and a lower steel plate that are fixedly connected in sequence from top to bottom. The layered steel plate and framework design can improve the overall stiffness.

[0068] The intersections of the longitudinal and transverse frameworks 331 are all located above the columns 310, as Figure 4 shown. This conducts the pressure on the upper steel plate more evenly to the lower steel plate, which is beneficial to reducing the risk of local deformation.

[0069] The middle plate support 340 includes short steel pipes 341 and / or spliced I-beams 342. It is simple to assemble and has a stable structure.

[0070] The width-depth ratio of each weld of the welded connection should not be less than 1.1. Controlling the width-depth ratio avoids brittle fracture caused by too deep welds, enhances the welding reliability, and improves the fatigue resistance and impact resistance of the structure.

[0071] The present embodiment provides an integral high-altitude upper plate circular shield construction method, which makes multiple improvements on the basis of the existing shield construction method. A circular shield tunnel is used to replace the original rectangular jacking tunnel, thereby reducing the reliance on pre-processing of bedrock protrusions and avoiding road occupation for construction. A reserved pit 121 is opened in the middle plate to construct a modular starting platform, thereby realizing the combination of permanent and temporary. While stably bearing the starting reaction force, the material waste and construction period investment of the temporary middle plate and full-hall scaffolding are saved. A split starting and full-process split excavation scheme is adopted to save the two hoisting constructions of the bridge frame and the trolley for going down and out of the well, and can adapt to complex construction conditions such as starting in narrow space, receiving in limited site, short tunnel, and crossing important roads.

[0072] Obviously, the above embodiments of the present invention are only examples for clearly illustrating the technical solution of the present invention, and are not intended to limit the specific implementation methods of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the claims of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A construction method for an integral high-altitude middle plate circular shield, characterized in that, It includes the following steps: S1. Arrange the construction site, construct the starting shaft, and a reserved pit is provided on the lower middle plate in the starting shaft; S2. Lift building materials into the starting shaft through the reserved pit to construct a shield starting platform for the high-altitude middle plate; S3. Lift each component of the shield main machine into the starting shaft, assemble the shield main machine, assemble the bridge and trolley on the ground and connect the bridge and trolley to the shield main machine through pipelines, debug the shield main machine, and install the negative ring segment; S4. Carry out split start, adopt split tunneling throughout the process, and ensure the connection between the shield main machine and the bridge and trolley by extending the pipeline; S5. Install the shield receiving bracket, the shield machine exits the tunnel and is received, and the shield main machine is lifted out of the receiving well; S6. Demolish the shield starting platform for the high-altitude middle plate, backfill the reserved pit on the lower middle plate, and reconstruct the upper middle plate.

2. The overall high-altitude middle plate circular shield construction method according to claim 1, characterized in that The distance between the starting shaft and the receiving well does not exceed 2 times the total length of the trolley.

3. The overall high-altitude middle plate circular shield construction method according to claim 1, characterized in that, The width of the receiving well is less than the length of the trolley.

4. A method for constructing an integral high-altitude middle plate circular shield according to any one of claims 1 to 3, characterized in that The long side of the reserved pit is provided with a tongue-and-groove, and the tongue-and-groove is provided with a first steel rail for supporting the shield main machine.

5. A method for constructing a circular shield for an overall high-altitude middle plate, according to any one of claims 1 to 3, characterized in that When excavating multiple tunnels at the height of the lower middle plate, in step S1, corresponding multiple reserved pits need to be opened. In step S4, the shield main machine starts separately in a certain reserved pit, and temporary supports are transversely arranged in other reserved pits.

6. The method for constructing a circular shield for an integral high-altitude middle plate according to claim 5, characterized in that, When excavating multiple tunnels in the same direction, in step S4, the shield machines of different tunnels can be tunneling simultaneously at different progress.

7. A construction method for an integral high-altitude middle plate circular shield according to any one of claims 1 to 3, characterized in that, In step S5, when the width of the receiving well is insufficient, the shield main machine is disassembled in the receiving well and then lifted out.

8. A method for constructing an integral high-altitude middle plate circular shield according to any one of claims 1 to 3, characterized in that, The shield starting platform for the high-altitude middle plate includes a starting frame and a reaction frame. The starting frame is fixed on the station floor slab, the top of the starting frame is lower than the lower middle plate and is fixedly connected to the lower middle plate, and the reaction frame is arranged on the starting frame.

9. A method for constructing an integral high-altitude middle plate circular shield according to claim 8, characterized in that, The reaction frame includes: A steel ring, arranged on the side close to the shield machine, for directly bearing the impact of the shield tail of the shield machine; A rear support frame, arranged on the side far from the shield machine and fixedly connected to the steel ring; A first diagonal brace, connecting the rear support frame and the structural beam of the upper middle plate; A second diagonal brace, connecting the rear support frame and the lower middle plate.

10. A method for constructing an integral high-altitude middle plate circular shield according to claim 8, characterized in that, The starting frame includes: Columns, the lower ends are connected to the floor slab of the station, and the upper ends are lower than the lower middle plate; A third diagonal brace, used to connect adjacent columns; A plate layer, laid on the upper ends of the columns, and one side is closely attached to the structural beam of the station under the starting portal; Multiple middle plate supports, located above the two columns on both sides of the shield direction, connected to the plate layer at the lower end and the lower middle plate at the upper end; A shield machine bracket, laid on the plate layer, under the starting portal, and between the two rows of middle plate supports. The shield machine bracket is provided with a second steel rail.

Images