A U-shaped shield machine with variable diameter and integrated paving and its construction method

Abstract

The present invention discloses a U-shaped shield machine with variable diameter and paving as one and a construction method thereof, which solves the problems in the prior art that the U-shaped shield cannot change the cross-section for excavation and the cushion paving efficiency is low. The U-shaped shield machine with variable diameter and paving as one of the present invention comprises a pipe-erecting machine system and a U-shaped tunneling machine. The U-shaped tunneling machine comprises a U-shaped shield frame with variable diameter. The front of the U-shaped shield frame is provided with a knife-inserting and edge-clearing mechanism. The front shield of the U-shaped shield frame is integrated with a grouting support system. The rear of the variable shield frame is provided with a paver and a jacking system. The present invention is an automated U-shaped shield machine that integrates the functions of lifting and assembling prefabricated pipe segments, automatic paving of pipe segment cushion layers, automatic grouting reinforcement around pipe segments, and adaptability to turns and cross-section changes in pipeline corridor construction. The paver completes the uniform paving of cushion media such as bottom concrete and medium-coarse sand, realizes leveling, reinforcement and waterproofing of the bottom of the pipe segment to be assembled and lowered, and improves the bearing capacity of the bottom of the pipe segment.

Description

Technical Field

[0001] The present invention relates to the technical field of U-shaped shield construction, and in particular to a variable-diameter paving integrated U-shaped shield machine and a construction method thereof. Background Art

[0002] Pipeline corridor construction typically uses a combination of slope support and cast-in-place construction, or pit support and cast-in-place construction. This process is complex and time-consuming. To accommodate the rapid, standardized, and prefabricated nature of pipeline corridor construction, mechanical methods for tunnel excavation have emerged. Existing technology includes a full-section, self-propelled U-shaped shield machine (TBM) with application number 201710108044.X. However, during construction, the cushion layer is laid using existing equipment. A hopper containing cushion material is hoisted underground by a crane and then manually laid. Calculations show that the cushion layer laying process accounts for more than half of the time required to advance a single ring of pipe segments, severely restricting construction efficiency. Furthermore, existing technology for U-shaped shield construction equipment is unable to adapt to cornering and variable-section excavation. Therefore, it is necessary to design comprehensive tunnel construction equipment that can adapt to cornering and variable-section tunnel excavation, while simultaneously integrating mechanized and automated excavation, support, assembly, cushion layer laying, and tunnel reinforcement. Summary of the Invention

[0003] In response to the deficiencies in the above-mentioned background technology, the present invention proposes a U-shaped shield machine with variable diameter and integrated paving and a construction method thereof, which solves the problems in the prior art that the U-shaped shield cannot change the cross-section for excavation and has low cushion paving efficiency.

[0004] The technical solution of the present invention is achieved as follows: a U-shaped shield machine with variable diameter and integrated paving includes a pipe erecting machine system and a U-shaped tunneling main machine. The U-shaped tunneling main machine includes a variable diameter U-shaped shield frame. The front of the variable diameter U-shaped shield frame is provided with a knife-inserting and edge-clearing mechanism. The front shield of the variable diameter U-shaped shield frame is integrated with a grouting support system. The rear of the variable diameter U-shaped shield frame is provided with a paver and a pushing system.

[0005] The variable diameter U-shaped shield frame includes a front shield, a middle shield and a tail shield, and the front shield, the middle shield and the tail shield are all split shield bodies; the front part of the middle shield is connected to the front shield through a hinged oil cylinder, and the rear part of the middle shield is fixedly connected to the tail shield. The knife edge cleaning mechanism is arranged at the front end of the front shield; the knife edge cleaning mechanism is a telescopic knife.

[0006] The front shield and the middle shield both include a left block, a right block, a bottom block I and a bottom block II. The left block and the right block are respectively connected to the bottom block I and the bottom block II to form a U-shaped shield body. A first telescopic adjustment member is provided between the left block and the right block, and a second telescopic adjustment member is provided between the bottom block I and the bottom block II.

[0007] The first telescopic adjustment member includes basic blocks respectively fixed on the left block body and the right block body, and standard blocks are detachably provided between the basic blocks; the second telescopic adjustment member includes an amplitude modulation cylinder and / or amplitude modulation block arranged between the bottom block I and the bottom block II, and the amplitude modulation block is detachably connected to the bottom block I and the bottom block II.

[0008] The first telescopic adjustment member includes an inner sleeve fixed on the left block body and an outer sleeve fixed on the right block body, the inner sleeve is sleeved in the outer sleeve, and the inner sleeve and the inner part of the outer sleeve are connected through a first oil cylinder; the second telescopic adjustment member includes passive wedges fixed on the bottom block I and the bottom block II respectively, and an active wedge is slidably fitted between the two passive wedges, and the active wedge is fixed by a positioning bolt, and a sleeve member is also provided between the bottom block I and the bottom block II.

[0009] The tail shield comprises a left shield body and a right shield body, and a third telescopic adjustment member is provided between the left shield body and the right shield body.

[0010] The third telescopic adjustment member includes a left-hand screw fixed on the left shield body and a right-hand screw fixed on the right shield body, and the left-hand screw is connected to the right-hand screw through a screw sleeve.

[0011] The grouting support system includes a fluidized solidified soil preparation system, a shield tail sealing system and a grouting system. The shield tail sealing system is detachably connected to the shield tail. The fluidized solidified soil preparation system includes a drying device, a screening and crushing device and a stirring device integrated in the front shield. The drying device, the screening and crushing device and the stirring device are connected in sequence. The stirring device is connected to an additive container, a curing agent container and a water tank. The output end of the stirring device is connected to the inlet end of the grouting system and extends backward to the shield tail sealing system.

[0012] The shield tail sealing system includes a tail shield mounting plate, on which two sealing structures are arranged front and rear along the excavation direction of the shield machine, and a pad is arranged between the two adjacent sealing structures; the front sealing structure is a polyurethane plate, and the rear sealing structure is a rubber plate; a reinforcement plate is provided at the connection between the polyurethane plate and the rubber plate and the tail shield mounting plate; each sealing structure includes a left seal, a right seal and a bottom seal, and the left seal, the right seal and the bottom seal form a sealed cavity structure with an upper opening.

[0013] When the U-shaped shield machine is pushed forward and the mixed slurry is backfilled into the fertilizer tank, the shield tail sealing system also includes a sealing push plate, which is connected to the middle shield or the tail shield through the pushing cylinder of the pushing system arranged axially; the tail shield mounting plate is installed at the axial tail of the sealing push plate.

[0014] The grouting system includes a three-way mixer, one inlet of the three-way mixer is connected to the fluid solidification soil pipe connected to the output end of the stirring device, the other inlet is connected to the admixture pipeline, the outlet end of the three-way mixer is connected to the slurry pipeline, and the liquid outlet of the slurry pipeline extends to the rear of the shield tail sealing system; the fluid solidification soil pipe, admixture pipeline, and slurry pipeline are all provided with flow meters.

[0015] The variable-diameter paving integrated U-shaped shield machine also includes an advance excavator, which corresponds to the fluidized solidified soil preparation system; a weighing mechanism is provided in the mixing device.

[0016] The paver includes a telescopic arm and a spreading head arranged at the shield position of a variable-diameter U-shaped shield frame. The spreading head is located at the telescopic front end of the telescopic arm. The spreading head includes a hopper assembly and a scraper assembly. The scraper assembly is located outside the hopper assembly.

[0017] The telescopic arm includes a fixed barrel section, a first telescopic arm and a second telescopic arm. A first telescopic cylinder is connected between the fixed barrel section and the first telescopic arm, and the first telescopic arm is telescoped relative to the fixed barrel section under the action of the first telescopic cylinder; a second telescopic cylinder is connected between the first telescopic arm and the second telescopic arm, and the second telescopic arm is telescoped relative to the first telescopic arm under the action of the second telescopic cylinder; wear-resistant blocks are provided inside the fixed barrel section and the first telescopic arm, and a first connecting piece for connecting to the hopper assembly and a second connecting piece for connecting to the scraper assembly are provided at the front of the second telescopic arm.

[0018] The hopper assembly includes a hopper, the bottom of the hopper is an arc-shaped bottom, a material dropout port is provided on the arc-shaped bottom, a material diverter shaft is provided in the hopper, and the material diverter shaft is connected to a driving device arranged on the outside of the hopper; the bottom of the hopper is an arc-shaped bottom formed by two arc-shaped plates, the material dropout port is located between the two arc-shaped plates, and the material diverter shaft is located in the arc-shaped bottom and corresponds to the arc-shaped bottom.

[0019] The material-discharging shaft includes a main shaft and a scraper plate fixed on the main shaft. There are at least two scraper plates, which are arranged at equal angles on the main shaft. Connecting shaft heads are provided at both ends of the main shaft. The connecting shaft head at one end is connected to the driving device, and the connecting shaft head at the other end is rotatably connected to the hopper wall.

[0020] The scraper assembly includes a scraper beam and a scraper. Both ends of the scraper beam are provided with vertically arranged lifting cylinders, and the scrapers are arranged at the telescopic ends of the two lifting cylinders. The scraper is an arc-shaped scraper, and the lifting cylinder is fixed to the scraper beam through a cylinder clamp. A laser receiver is provided on the upper part of the scraper beam.

[0021] The paver includes an upper silo and a spiral separator. The upper silo is connected to the spiral separator through a discharge pipe. The discharge side of the spiral separator is provided with a cushion scraping mechanism that can move up and down. The cushion scraping mechanism moves laterally along the spiral separator under the action of the transverse transmission mechanism; the discharge pipe is connected to a variable diameter U-shaped shield through a suspension part, and the cushion scraping mechanism is connected to the tail shield of the variable diameter U-shaped shield through a lifting cylinder.

[0022] The spiral separator includes a box-shaped trough body, a feed hopper is provided in the middle of the box-shaped trough body, and several discharge hoppers are provided on the outer wall of the box-shaped trough body. A spiral shaft is provided for rotation inside the box-shaped trough body, and the spiral shaft is connected to a driving member provided on the box-shaped trough body; a movable baffle is provided between the discharge hopper and the box-shaped trough body, and a cover plate corresponding to the discharge hopper is provided on the top wall of the box-shaped trough body.

[0023] The spiral shaft includes a left spiral shaft and a right spiral shaft arranged coaxially, the left spiral shaft and the right spiral shaft are connected by a self-aligning bearing, the self-aligning bearing is fixed in the box-shaped trough body through a bearing seat, and the spiral direction of the spiral blade on the left spiral shaft is opposite to the spiral direction of the spiral blade on the right spiral shaft; the driving part includes a left motor and a right motor, the left motor is connected to the left spiral shaft, and the right motor is connected to the right spiral shaft.

[0024] The cushion layer scraping mechanism includes a supporting rail frame located outside the spiral separator, with lifting cylinders provided at both ends of the supporting rail frame, a scraper assembly slidingly provided on the supporting rail frame, and the scraper assembly moves along the supporting rail frame through a transverse transmission mechanism; the scraper assembly includes a sliding seat provided on the supporting rail frame, a crossbeam hinged on the sliding seat, the crossbeam is connected to the sliding seat through an adjusting cylinder, and a scraper is fixed to the lower part of the crossbeam; a support rod is fixed to the side of the crossbeam, and a pressure roller is provided on the support rod.

[0025] The support rail frame is a rectangular frame structure; an extension block is detachably connected to the rectangular frame structure, the sliding seat is a concave seat, the concave seat is in sliding contact with the rectangular frame structure, and rolling elements are provided on the contact surfaces corresponding to the sliding seat and the support rail frame.

[0026] The transverse transmission mechanism includes a driving sprocket rotatably arranged on one side of the supporting rail frame and a driven sprocket rotatably arranged on the other side of the supporting rail frame, the driving sprocket is connected to a driving motor or a driving motor arranged on the supporting rail frame, a transmission chain is connected between the driving sprocket and the driven sprocket, and the sliding seat is fixed on the transmission chain; a tensioner cooperating with the transmission chain is provided on the supporting rail frame.

[0027] The tensioner includes a tensioning seat and a tensioning cylinder. The tensioning seat is fixed to the telescopic end of the tensioning cylinder, and the fixed end of the tensioning cylinder is fixed to the supporting rail frame through a supporting seat. The tensioning seat is an arc-shaped seat, and an arc-shaped groove is provided on the arc-shaped seat to match the transmission chain.

[0028] The pipe erection machine system includes a gantry frame, the forward end of the gantry frame is detachably connected to a variable diameter U-shaped shield frame, the driven end of the gantry frame is provided with a walking wheel, and the gantry frame is provided with a pipe segment hoist.

[0029] A construction method of the variable-diameter paving integrated U-shaped shield machine comprises the following steps:

[0030] S1: According to the cross-sectional width of the tunnel to be excavated, the width of the variable diameter U-shaped shield is adjusted so that the outer contour of the variable diameter U-shaped shield meets the cross-sectional dimension requirements of the channel;

[0031] S2: During the tunneling process of the U-shield machine, the paver spreads the cushion paving material in the paving area horizontally or vertically;

[0032] S3: The pipe erecting machine system assembles the pipe segments synchronously. The advance excavator located in front of the U-shield machine cooperates with the grouting support system to prepare the fluidized solidified soil. The prepared mixed slurry is then backfilled into the fertilizer trough formed between the side wall of the pipe segment and the original soil, achieving synchronous fertilizer trough backfilling.

[0033] S4: Repeat steps S2 and S3 until the excavation and support of the entire channel are completed.

[0034] In step S2, the process of the paver uniformly paving the cushion paving material in the paving area in the transverse direction is as follows: A1: a laser transmitter is set up at a suitable position behind the U-shaped shield machine, and the laser transmitter corresponds to the laser receiver set on the spiral separator;

[0035] A2: When paving begins, the cushion paving material in the upper silo enters the spiral separator through the discharge pipe; then it is discharged through the discharge hopper of the spiral separator;

[0036] A3: The laser receiver receives the laser light from the laser transmitter and determines the position of the U-shaped shield machine. When the U-shaped shield machine is parallel to the ground elevation, the cushion layer scraping mechanism of the transverse cushion layer paver performs transverse reciprocating motion under the action of the transverse transmission mechanism, and the cushion layer paving material is evenly spread.

[0037] A4: When the U-shaped shield machine is not parallel to the ground elevation, the overall lateral inclination angle of the cushion scraping mechanism is adjusted by the lifting cylinder, and then the longitudinal inclination angle of the scraper of the cushion scraping mechanism is adjusted by the adjustment cylinder of the cushion scraping mechanism to make the scraper of the cushion scraping mechanism parallel to the ground elevation. Then, the scraper of the cushion scraping mechanism performs a lateral reciprocating motion under the action of the lateral transmission mechanism to evenly spread the cushion paving material.

[0038] A5: When the cross-section of the paving area changes, variable-section paving is required; add extension blocks to the support rails of the cushion layer scraping mechanism to increase the overall length of the support rails to adapt to the variable-section paving area. At the same time, adjust the length of the transmission chain of the transverse transmission mechanism through the tensioner to ensure that the scraper of the cushion layer scraping mechanism can stably perform transverse reciprocating motion, so as to achieve uniform paving of the cushion layer paving material in the variable-section paving area.

[0039] In step S2, the process of the paver uniformly paving the cushion paving material in the paving area longitudinally is as follows: B1: the U-shaped shield machine advances a certain distance in the excavation direction to provide construction space for the paver;

[0040] B2: The telescopic arm drives the spreading head to move back and forth along the excavation direction, spreading the cushion paving material evenly in the longitudinal direction;

[0041] B3: When the cross-section of the paving area changes, change the position and number of the paver on the variable diameter U-shaped shield so that the spreading head can cover the entire paving area and achieve uniform paving of the cushion paving material in the variable cross-section paving area.

[0042] The specific process of backfilling the fertilizer tank in step S3 is as follows:

[0043] S3.1 Preparation of fluidized solidified soil: The excavator delivers the excavated soil directly or after drying to the screening and crushing device. The screening and crushing device crushes and screens the soil. The screened portion of the soil is fed into the mixing device in a certain proportion. The admixture container, curing agent container, and water tank simultaneously add a certain proportion of admixture, curing agent, and water to the mixing device. The mixing device then stirs the materials therein to form fluidized solidified soil. The amount of fluidized solidified soil in the mixing device must meet the backfill requirements of at least one ring of pipe segments.

[0044] S3.2 Grouting: The admixture and the fluidized solidified soil prepared in step S1 are pumped into the three-way mixer of the grouting system respectively to form a mixed slurry. The mixed slurry is pumped through the mixing pipeline to the rear of the shield tail sealing system for backfilling the fertilizer tank;

[0045] S3.3 Sealing: While grouting is being performed in step S2, the shield tail sealing system will synchronously seal the mixed slurry to prevent the slurry from flowing back to the tail shield.

[0046] S3.4: Repeat steps S1 to S3 until all segments are assembled.

[0047] The specific process of step S3.3 includes two working conditions: injecting the mixed slurry into the fertilizer tank while pushing forward and backfilling the mixed slurry into the fertilizer tank after pushing forward is completed;

[0048] The specific process of injecting the mixed slurry into the fertilizer tank while advancing is as follows: when one pipe section is laid, the mixed slurry has solidified, and the fluidized solidified soil required for the next pipe section has been prepared in the mixing device; the U-shaped shield machine continues to advance forward, and the grouting system continues to inject the mixed slurry into the fertilizer tank after advancing, and the cycle continues;

[0049] The specific process of backfilling the mixed slurry into the fertilizer tank after the advancement is completed is as follows: when one section of the pipe is laid and before the U-shaped shield machine starts to advance the next ring, the mixed slurry has not yet solidified, and the sealing push plate of the tail sealing system is pressed backward on the laid pipe section; the thrust cylinder pushes the shield machine forward, and the push plate is stationary relative to the pipe section; after the thrust cylinder completes the advancement, the mixed slurry can solidify, and then the sealing push plate is retracted, and the mixed slurry is injected into the fertilizer tank after advancement, and the cycle continues.

[0050] The present invention is an automated U-shaped shield machine that integrates the functions of lifting and assembling prefabricated pipe segments, automatically spreading the pipe segment cushion layer, automatically grouting and reinforcing the pipe segment periphery, and adapting to pipe corridor construction turns and variable cross-sections. The paver completes the uniform spreading of bottom concrete, medium-coarse sand and other cushioning media, thereby achieving leveling, reinforcement and waterproofing of the bottom of the pipe segment to be assembled and lowered, and improving the bearing capacity of the bottom of the pipe segment. The use of a variable diameter U-shaped shield frame can, on the one hand, cooperate with the equipment to adapt to the construction support of pipe corridors with different cross-sections. On the other hand, the widened support formed by the expansion and contraction of the shield body when the equipment turns can effectively avoid interference and jamming between the pipe segments and the tail shield during the turning movement, thereby improving construction efficiency and construction safety factor. After the fluidized solidified soil solidifies, the grouting support system of the present invention completely fills the gap behind the wall, and has strong supporting strength and waterproofing effect. The raw materials of the fluidized solidified soil can be obtained locally, and the material cost is low. Compared with the filling concrete method, the preparation and grouting of the fluidized solidified soil of the present invention are convenient, the solidification time is short, the construction efficiency is improved, and the material cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0052] Figure 1 It is a schematic diagram of the overall structure of the U-shaped shield machine of the present invention.

[0053] Figure 2 It is a top view schematic diagram of the variable diameter U-shaped shield frame of the present invention.

[0054] Figure 3 Schematic diagram of the front shield structure.

[0055] Figure 4This is a schematic diagram of the Zhongdun structure.

[0056] Figure 5 This is a schematic structural diagram of the first telescopic adjustment member in Example 2.

[0057] Figure 6 This is a schematic structural diagram of the second telescopic adjustment member in Example 2.

[0058] Figure 7 Schematic diagram of the tail shield structure.

[0059] Figure 8 Schematic diagram of the grouting support system structure.

[0060] Figure 9 Schematic diagram of the structure of the fluidized solidified soil preparation system.

[0061] Figure 10 Schematic diagram of the grouting system structure.

[0062] Figure 11 for Figure 8 Center AA view.

[0063] Figure 12 for Figure 8 Middle BB view.

[0064] Figure 13 Schematic diagram of the shield tail sealing system with a sealing push plate.

[0065] Figure 14 Schematic diagram of the paver structure for longitudinal paving.

[0066] Figure 15 Schematic diagram of the telescopic arm structure.

[0067] Figure 16 Schematic diagram of the hopper assembly structure.

[0068] Figure 17 Schematic diagram of the scraper assembly structure.

[0069] Figure 18 Schematic diagram of the paver structure for horizontal paving.

[0070] Figure 19 Schematic diagram of the internal structure of the spiral separator.

[0071] Figure 20 It is a schematic diagram of the cushion layer scraping mechanism structure.

[0072] Figure 21 Schematic diagram of the cushion scraping mechanism under variable diameter working conditions.

[0073] Figure 22 for Figure 21 A partial enlarged view of point F in the middle.

[0074] Figure 23 Schematic diagram of the tensioner structure.

[0075] Figure 24 This is the flow chart for the horizontal paving control during the U-shaped shield construction process. DETAILED DESCRIPTION

[0076] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0077] like Figure 1As shown in Example 1, a U-shaped shield machine with a variable diameter and integrated paving system includes a pipe-erecting system 10 and a U-shaped tunneling machine. The pipe-erecting system 10 includes a gantry frame. The forward end of the gantry frame is detachably connected to the variable diameter U-shaped shield frame 1 of the U-shaped tunneling machine. The driven end of the gantry frame is provided with running wheels, and the gantry frame moves synchronously with the U-shaped tunneling machine. The gantry frame is provided with a pipe segment hoist 9 for hoisting the pipe segments; the hoist cooperates with the pipe segment transport trolley 8 to transport the pipe segments 7. The U-shaped tunneling machine includes a variable diameter U-shaped shield frame 1, the width of which can be adjusted to accommodate variable cross-section excavation. The front of the variable diameter U-shaped shield frame 1 is provided with a blade clearing mechanism 2, which is used to clear the excavation surface of the advance excavator 6 to form a relatively flat and regular excavation surface. The advance excavator 6, at the front end of the equipment, completes excavation at the front end of the tunnel corridor. The shield follows closely behind the excavator, supporting the tunnel and preventing side soil collapse. The front shield of the variable-diameter U-shaped shield 1 incorporates a grouting support system 3. This system prepares fluidized solidified soil and forms a mixed slurry, which is used to backfill the gap (fertilizer trough) of a certain width between the sidewalls of the tunnel segment and the original soil. The rear of the variable-diameter U-shaped shield 1 is equipped with a paver 4 and a jacking system 5. The paver 4 can be used to pave horizontally (perpendicular to the direction of shield machine advancement), spreading the material horizontally across the paving area. It can also be used to pave longitudinally (along the direction of shield machine advancement), spreading the material longitudinally across the paving area. The jacking system 5 uses a jacking cylinder to provide the forward propulsion power of the U-shaped shield. Specifically, the jacking system is set up around the middle shield and consists of multiple jacking cylinders. One end of the jacking cylinder pushes against the assembled pipe segments inside the rear shield, and the other end pushes against the shield body. The jacking cylinders rely on the reaction force of the interaction with the pipe segments to complete the forward propulsion of the shield body as a whole. After the distance between the pipe segment and the jacking cylinder is sufficient to assemble a pipe segment, the propulsion and excavation are stopped, and the paving of the bottom layer of the pipe segment begins. In addition, the U-shaped shield machine also includes a rear supporting system, which includes a hydraulic pump station, an electrical control system, a grouting reinforcement system, and other devices to complete the power supply and auxiliary construction of the entire equipment.

[0078] As a preferred solution, Figure 2As shown, the variable-diameter U-shaped shield 1 comprises a front shield 1-1, a middle shield 1-2, and a tail shield 1-3. Each of these shields is a split-piece structure. Specifically, the front and middle shields 1-1 and 1-2 can be assembled from three pieces, while the tail shield 1-3 can be assembled from two pieces, enabling the variable-diameter U-shaped shield 1 to vary in diameter (or width). The front portion of the middle shield 1-2 is connected to the front shield 1-1 via an articulated cylinder 1-4. This design allows for articulated correction and turning of the front shield. The rear portion of the middle shield 1-2 is fixedly connected to the tail shield 1-3, providing support for tunnel construction. A blade-splitting mechanism 2 is located at the front end of the front shield 1-1, i.e., on the left and right lower end surfaces, to facilitate excavation and clearing of U-shaped tunnels. The knife edge cleaning mechanism 2 is a telescopic knife. The knife edge cleaning mechanism can adopt the knife structure in the prior art and can perform edge cleaning on the left and right bottom three sides of the U-shaped tunnel after excavation.

[0079] like Figure 3 、 4 As shown, the front shield 1-1 and the middle shield 1-2 can be assembled into three pieces. Specifically, the front shield 1-1 and the middle shield 1-2 each include a left sub-block 101, a right sub-block 102, a bottom sub-block I 103, and a bottom sub-block II 104. The left sub-block 101 and the right sub-block 102 are connected to the bottom sub-block I 103 and the bottom sub-block II 104, respectively, to form a U-shaped shield. A first telescopic adjustment member is provided between the left sub-block 101 and the right sub-block 102, and a second telescopic adjustment member is provided between the bottom sub-block I 103 and the bottom sub-block II 104. The first and second telescopic adjustment members cooperate to adjust the width of the front shield 1-1 and the middle shield 1-2, thereby achieving turning and diameter change.

[0080] Specifically, the first telescopic adjustment member includes base blocks 105 fixed to the left and right sub-blocks 101 and 102, respectively. Standard blocks 106 are removably installed between the base blocks 105. The number and size of the standard blocks are selected based on the width of the tunnel section. When width adjustment is required, a standard block is added between the two base blocks. When width adjustment is not required, the standard block is removed. The second telescopic adjustment member includes an amplitude modulation cylinder 107 and / or an amplitude modulation block 108 disposed between bottom sub-block I 103 and bottom sub-block II 104. The amplitude modulation cylinder 107 and the amplitude modulation block 108 can be present simultaneously, or only the amplitude modulation cylinder can be retained. Under the action of the amplitude modulation cylinder, the relative distance between bottom sub-block I 103 and bottom sub-block II 104 is adjusted to adjust the width of the shield bottom surface. The amplitude modulation block 108 is detachably connected to bottom sub-block I 103 and bottom sub-block II 104, performing amplitude modulation, support, and connection functions to ensure the overall stability of the shield.

[0081] like Figure 5 、 6As shown, Example 2, a U-shaped shield machine with a variable diameter and integrated paving, differs from Example 1 in that the first telescopic adjustment member in this embodiment comprises an inner sleeve 101a fixed to the left block 101 and an outer sleeve 102a fixed to the right block 102. Inner sleeve 101a is sleeved within outer sleeve 102a, and the inner and outer sleeves 101a and 102a are connected internally by a first oil cylinder. During actual construction, the overlapping area of the inner and outer sleeves is adjusted by the first oil cylinder to adjust the overall width of the shield. The second telescopic adjustment member includes a passive wedge 103a fixed to bottom block I 103 and bottom block II 104, respectively. An active wedge 104a slidably engages between the two passive wedges 103a. Before construction, the relative distance between bottom block I 103 and bottom block II 104 is adjusted, and then positioned using the active wedge 104a. The relative distance between the two passive wedges 103a can also be adjusted by the longitudinal movement of the active wedge 104a (movement in the direction of the tunneling machine). The active wedge 104a is then secured with positioning bolts to ensure the stability of the wedge-shaped adjustment mechanism. Furthermore, if desired, a sleeve 105a can be provided between bottom block I 103 and bottom block II 104 to further stabilize the shield. This sleeve can be a cylinder sleeve, with the inner and outer barrels of the sleeve fixed to bottom block I and bottom block II, respectively, to stabilize the blocks.

[0082] Further, if Figure 7 As shown, the tail shield 1-3 comprises a left shield body 301 and a right shield body 302, respectively connected to the left and right blocks of the middle shield. A third telescopic adjustment member is provided between the left and right shield bodies 301 and 302. This third telescopic adjustment member can adopt the structural design of the first or second telescopic adjustment member. Alternatively, a structural design may be employed: the third telescopic adjustment member comprises a left-handed screw 303 fixed to the left shield body 301 and a right-handed screw 304 fixed to the right shield body 302. The left-handed screw 303 is connected to the right-handed screw 304 via a threaded sleeve 305. During amplitude modulation, the distance between the left and right shield bodies 301 and 302 is adjusted by rotating the threaded sleeve, thereby adjusting the width of the tail shield. Under normal circumstances, the widths of the front, middle, and tail shields are adjusted synchronously to accommodate variable-diameter excavation. These widths can also be adjusted in varying proportions to accommodate small-diameter turns. The front, middle, and tail shields expand and contract in real time. This telescopic structure not only adapts the equipment to support tunnel construction of varying cross-sections, but also creates a wider support structure when the equipment turns, effectively preventing interference and jamming between the segments and tail shields during turning movements.

[0083] like Figure 8 、 9As shown, Example 3 is a U-shaped shield machine with a variable diameter and integrated paving system. Based on Example 1 or 2, the grouting support system 3 includes a fluidized solidified soil preparation system 31, a shield tail sealing system 32, and a grouting system 33. The fluidized solidified soil preparation system 31 is used to prepare fluidized solidified soil; the shield tail sealing system 32 is used to seal the grouting slurry to prevent it from flowing back into the shield body. The grouting system 33 is used to pump the prepared slurry to a fixed point to achieve efficient fertilizer tank backfilling. The shield tail sealing system 32 is detachably connected to the shield tail to prevent the slurry from flowing back into the shield body. The fluidized solidified soil preparation system 31 includes a drying device 31-1, a screening and crushing device 31-2, and a stirring device 31-3, all integrated within the front shield. These three devices are interconnected. Drying device 31-1 dries the relatively wet excavated soil, while screening and crushing device 31-2 screens and crushes the soil, delivering the soil that meets the required particle size to the stirring and conveying device. The stirring device 31-3 is connected to an admixture container 31-4, a curing agent container 31-5, and a water tank 31-6. The admixture (including water reducer, water glass, etc.) in admixture container 31-4, the curing agent in curing agent container 1-5, and the water in water tank 31-6 are injected into the stirring device in a predetermined ratio. The stirring device then stirs the fluidized solidified soil, forming the fluidized solidified soil. The soil screening and crushing device, water tank, curing agent container, and additive container are all equipped with connecting valves at the bottom. By opening these valves, various materials are added to the mixing device. Each container and the lower portion of the device are equipped with a weighing function to ensure that the required amount of grouting is injected into a ring of pipe segments at a time. The output end of the mixing device 31-3 is connected to the inlet end of the grouting system 33 and extends backward to the shield tail sealing system 32. The fluidized solidified soil is poured into the gap (fertilizer trough) of a certain width between the pipe segment sidewall and the original soil under the grouting system, completing the backfill. The shield tail sealing system 32 also acts as a seal to prevent the backflow of the pouring liquid. This structural design is highly compatible with the U-shaped shield machine. Using excavated soil to backfill the fertilizer trough greatly improves the grouting process and construction efficiency, while also reducing construction costs.

[0084] In this embodiment, Figure 11 、 12As shown, the tail shield sealing system 32 includes a tail shield mounting plate 2-1. In this embodiment, the tail shield mounting plate is fixed to the tail shield of the U-shaped shield machine. Two sealing structures are arranged on the tail shield mounting plate 2-1 in front and behind along the tunneling direction of the shield machine, and a pad 2-2 is arranged between the two adjacent sealing structures. Both sealing structures are fixed to the tail shield mounting plate by bolts. To improve wear resistance and sealing performance, the front sealing structure is a polyurethane plate 2-3, and the rear sealing structure is a rubber plate 2-4. A reinforcement plate 2-5 is provided at the connection between the polyurethane plate 2-3 and the rubber plate 2-4 and the tail shield mounting plate 2-1. The provision of the reinforcement plate not only improves the wear resistance of the polyurethane plate 2-3 and the rubber plate 2-4, but also improves their strength and sealing performance. Each sealing structure includes a left seal 21, a right seal 22, and a bottom seal 23. The left seal 21, the right seal 22, and the bottom seal 23 form a sealed cavity structure with an upper opening. Specifically: one end of the right seal is fixed on the mounting plate, and the other end extends out to press the pipe wall to prevent the fluidized solidified soil from flowing out along the pipe wall; one end of the bottom seal is fixed on the mounting plate, and the other end extends out to press the ground and the original soil on the left to prevent the fluidized solidified soil from flowing out along the bottom ground and the original soil on the left; one end of the left seal is fixed on the mounting plate, and the other end extends out to press the original soil on the left to prevent the fluidized solidified soil from flowing out along the original soil on the left.

[0085] like Figure 13 As shown, Example 4 is a U-shaped shield machine with a variable diameter and integrated paving. On the basis of Example 3, when the U-shaped shield machine is pushed forward and the mixed slurry is backfilled into the fertilizer tank, the shield tail sealing system 32 also includes a sealing push plate 24, and the sealing push plate 24 is connected to the middle shield or the tail shield through the axially arranged pushing cylinder 25 of the pushing system 5; the tail shield mounting plate 2-1 is installed at the axial tail of the sealing push plate 24. In this embodiment, the pushing cylinder 25 is arranged at the tail of the middle shield, and the push plate is fixed on the pushing cylinder and moves with the pushing cylinder. A shield tail sealing device is installed at the tail of the sealing push plate. When the pipe segment is laid and the next ring is pushed forward, the fluidized solidified soil cannot solidify yet. The pushing cylinder pushes the shield machine forward, and the push plate is stationary relative to the pipe segment. After the fluidized solidified soil solidifies, generally the pushing cylinder is pushed completely, and the fluidized solidified soil can solidify. At this time, the pushing cylinder retracts the push plate, fills the fluidized solidified soil, lowers the new pipe segment, and prepares for the next ring to be pushed forward. The cycle works until the whole process is completed.

[0086] In this embodiment, if Figure 10As shown, the grouting system 33 includes a three-way mixer 33-1. One inlet of the three-way mixer 33-1 is connected to a fluid-cured soil pipe 33-2 connected to the output end of the stirring device 31-3, and the other inlet is connected to an admixture line 33-3. The admixture line 33-3 is connected to an admixture container 31-4. The admixture can be water glass, which reduces the setting time of the fluid-cured soil. After the fluid-cured soil and water glass are mixed, they are transported through a pipeline to the grouting port and grouting is injected into the wall. The outlet end of the three-way mixer 33-1 is connected to a slurry mixing line 33-4, the liquid outlet of which extends to the rear of the shield tail sealing system 32. The fluid-cured soil pipe 33-2, the admixture line 33-3, and the slurry mixing line 33-4 are all equipped with flow meters to ensure the grouting volume and improve the grouting quality. During the construction process, the admixtures in the admixture container can also be put into the stirring device 1-3 to be fully stirred and mixed with other materials, and then directly filled into the fertilizer tank through the fluidized solidification soil pipe and the slurry mixing pipeline. In this case, the three-way mixer can be removed. The way of adding water glass determines two fluidized solidification soil production processes, namely: 1. Directly add water glass and other ingredients into the stirring and conveying device, mix and stir them together in the stirring and conveying device. In order to prevent the fluidized solidification soil from solidifying prematurely or changing its state, such as segregation, water glass is generally added to the stirring and conveying device last; 2. Except for water glass, other ingredients are first added to the stirring and conveying device to be mixed and stirred evenly. When the fluidized solidification soil is to be backfilled, the water glass and other materials that have been mixed and stirred evenly in the stirring and conveying device are mixed through the pipeline and then injected into the fertilizer tank of the pipeline corridor.

[0087] The variable-diameter paving U-shield machine also includes an advance excavator 6, which corresponds to the fluidized solidified soil preparation system 31. The mixing device 31-3 is equipped with a weighing mechanism. Specifically, the advance excavator 6, located at the front of the U-shield machine, performs advance excavation and delivers the excavated soil to the drying device or screening and crushing device 31-2 in preparation for fluidized solidified soil preparation. In this embodiment, the mixing device 31-3 is equipped with a weighing mechanism to measure the weight of the material entering the mixing device, ensuring the accuracy of the fluidized solidified soil preparation.

[0088] like Figure 14As shown, Example 5 is a U-shaped shield machine with variable diameter paving. On the basis of Example 4, the paving machine of this embodiment adopts longitudinal paving. The specific structure is: the paving machine 4 includes a telescopic arm 41 and a spreading head arranged in the shield position of the variable diameter U-shaped shield frame 1. The telescopic arm provides telescopic movement for the spreading head, which is convenient for uniform material unloading and leveling. The spreading head is located at the telescopic front end of the telescopic arm 41. The spreading head includes a hopper assembly 42 and a scraper assembly 43. The scraper assembly 43 is located on the outside of the hopper assembly 42. The hopper assembly 42 is used to hold the cushion material and spread the material in time, and the scraper assembly is used to scrape the cushion material. The scraper assembly 43 and the hopper assembly 42 are arranged one after the other to achieve simultaneous paving and leveling, thereby improving paving efficiency.

[0089] Further, if Figure 15 As shown, the telescopic arm 41 includes a fixed barrel section 11, a first telescopic arm 12, and a second telescopic arm 13. A first telescopic cylinder 14 is connected between the fixed barrel section 11 and the first telescopic arm 12. The first telescopic arm 12 is extended and retracted relative to the fixed barrel section 11 by the first telescopic cylinder 14. The fixed end of the first telescopic cylinder 14 is pin-mounted to a cylinder hinge seat provided on the fixed barrel section 11, while the telescopic end is pin-mounted to a cylinder hinge seat provided on the first telescopic arm 12. The first telescopic cylinder controls the extension and retraction speed of the first telescopic arm. A second telescopic cylinder 15 is connected between the first telescopic arm 12 and the second telescopic arm 13. The second telescopic cylinder 15 controls the extension and retraction speed of the second telescopic arm. The fixed end of the second telescopic cylinder 15 is pin-mounted to a cylinder hinge seat provided on the first telescopic arm 12, while the telescopic end is pin-mounted to a cylinder hinge seat provided on the second telescopic arm 13. The second telescopic cylinder controls the extension and retraction speed of the second telescopic arm. The telescopic arm 41 of this embodiment adopts a three-section arm structure, which increases the telescopic distance of the paving head along the tunnel axis and expands the operating range. Wear-resistant blocks 111 are provided inside the fixed cylinder section 11 and the first telescopic arm 12 to prevent the telescopic arm structure from being worn through. The front portion of the second telescopic arm 13 is provided with a first connecting member 18 for connecting to the hopper assembly 42 and a second connecting member 19 for connecting to the scraper assembly 43. The second connecting member 19 and the second connecting member fixedly connect the scraper assembly 43 and the hopper assembly 42 to the second telescopic arm 13, enabling the scraper assembly 43 and the hopper assembly 42 to move synchronously with the second telescopic arm. During the actual construction process: when the first telescopic arm extends, the first telescopic cylinder extends at the design speed, and the second telescopic cylinder does not move. When the first telescopic cylinder reaches the limit position, the second telescopic cylinder extends at the design speed, so that the telescopic arm extends at a uniform speed; when the first telescopic arm retracts, the first telescopic cylinder retracts at the design speed, and the second telescopic cylinder does not move. When the first telescopic cylinder retracts to the limit position, the second telescopic cylinder retracts at the design speed, so that the telescopic arm retracts at a uniform speed.

[0090] Further, if Figure 16 As shown, the hopper assembly 42 includes a hopper 420, which is welded from steel plates. Before the hopper works, a certain amount of cushioning material needs to be loaded into the hopper to prevent the rotating shaft from idling. The bottom of the hopper 420 is an arc-shaped bottom, and a drop-out port 421 is provided on the arc-shaped bottom to facilitate discharging. A material-discharging shaft 422 is provided in the hopper 420, and the material-discharging shaft 422 is connected to a driving device provided on the outside of the hopper 420; under the action of the driving device, the material-discharging shaft rotates to discharge the material in the hopper through the drop-out port, so as to achieve timely and uniform material laying. The bottom of the hopper 420 is an arc-shaped bottom formed by two arc-shaped plates 426, the drop-out port 421 is located between the two arc-shaped plates 426, and the material-discharging shaft 422 is located in the arc-shaped bottom and corresponds to the arc-shaped bottom. A gap is left between the outer edge of the material-digging shaft and the inner wall of the arc plate to avoid scraping between the two when the material-digging shaft rotates. When the material-digging shaft does not rotate, the cushion material will not spill from the gap due to the self-locking property of the cushion material itself; when the material-digging shaft rotates, the cushion material falls from the slot to the ground through the cutting action of the material-digging shaft.

[0091] The material diverter shaft 422 comprises a main shaft 22-1 and a scraper plate 22-2 fixed to the main shaft. There are at least two scraper plates 22-2, arranged at equal angles on the main shaft 22-1. In this embodiment, there are four scraper plates 22-2, evenly spaced at 90° angles. This ensures that the cushioning material is blocked by the scraper plates regardless of the position of the main shaft 22-1. A gap is left between the outer edge of the scraper plate and the inner wall of the curved plate to prevent the two from scraping when the shaft rotates. The main shaft 22-1 is provided with connecting shaft heads at both ends. One end of the connecting shaft head is connected to the drive device, and the other end of the connecting shaft head is rotatably connected to the wall of the hopper 420. The connecting shaft head is circular on the outside and square on the inside. The small outer end is inserted into the seamless steel pipe, and the large outer end is welded to the seamless steel pipe. The inner square hole is connected to the drive end and the support end shaft extension, which serves to transmit torque. The drive device can be a drive motor + reducer to provide power for the diverter shaft rotation.

[0092] like Figure 17As shown, the scraper assembly 43 includes a scraper beam 431 and a second scraper 433. Both ends of the scraper beam 431 are provided with vertically arranged lifting cylinders 432, and the second scraper 433 is arranged at the telescopic ends of the two lifting cylinders 432. Specifically, the telescopic rod of the scraper lifting cylinder is hinged to the scraper through a pin shaft, so that the scraper can be at a certain angle to the horizontal plane to adapt to the angle deviation caused by the tilt of the U shield itself. By retracting and extending the two lifting cylinders, the inclination angle of the scraper can be adjusted to adapt to different construction environments. The second scraper 433 is an arc-shaped scraper, which evenly spreads the cushion material. The lifting cylinder 432 is fixed to the scraper beam 431 by a cylinder clamp 434, realizing a detachable connection of the lifting cylinder. The scraper beam is modified from a rectangular tube, and a connecting flange is welded in the middle of the scraper beam, which is connected to the connecting flange at the front end of the telescopic arm by high-strength bolts. Slots are provided at both ends of the scraper beam to allow the scraper lift cylinder to pass through. Fixing plates with threaded holes are welded to either side of the slots, allowing the cylinder clamp to be mounted on the fixing plates. The upper opening of the cylinder clamp mates with the scraper lift cylinder pin, providing axial positioning for the scraper lift cylinder. A laser receiver 435 is located on the upper portion of the scraper beam 431. Laser signals from a laser transmitter are received to control the extension and retraction of the cylinder, enabling synchronous leveling and ensuring accurate paving of the subgrade. The laser receiver collects elevation laser signals and feeds them back to the control system via the CAN bus. When the shield machine's inclination sensor indicates the machine is horizontal, the two laser receivers are set to the same elevation difference. During scraper movement, the control system calculates the relative elevation difference between the lift cylinders on both sides, thereby controlling the solenoid valves and causing the lift cylinders to move accordingly, keeping the scraper at the set elevation. When the shield machine's inclination sensor indicates a certain inclination, the two laser receivers are set to a height difference corresponding to the inclination. As the scraper moves, the control system calculates the relative height difference between the lifting cylinders on both sides, thereby controlling the solenoid valves and moving the lifting cylinders accordingly, keeping the scraper at a certain inclination. By inputting parameters such as the cushion thickness and paving speed, the control system calculates the corresponding rotary motor speed and telescopic arm extension speed. This is used to control the shaft speed and telescopic arm movement speed, ensuring that the two match and achieve the desired cushion thickness within the set time.

[0093] like Figure 18As shown, Example 6 is a U-shaped shield machine with variable diameter paving. The difference from Example 5 is that the paver 4 in this embodiment adopts transverse paving. The specific mechanism is: the paver 4 includes an upper silo 41a and a spiral separator 43a, and the upper silo and the spiral separator are arranged one above and one below. The upper silo 41a is connected to the spiral separator 43a through the discharge pipe 42a, and the cushion paving material in the upper silo enters the spiral separator through the discharge pipe. The discharge side of the spiral separator 43a is provided with a cushion scraping mechanism 44a that can move up and down. The cushion scraping mechanism scrapes the cushion paving material flowing out of the spiral separator to achieve uniform paving. The cushion scraping mechanism 44a moves laterally along the spiral separator 43a under the action of the transverse transmission mechanism 45a; that is, the scraper member of the cushion scraping mechanism of the present invention performs transverse reciprocating motion under the action of the transverse transmission mechanism to achieve efficient paving. The discharge pipe 42a is connected to the variable-diameter U-shaped shield 1 via a suspension, and the cushion-scraping mechanism 44a is connected to the rear shield portion of the variable-diameter U-shaped shield 1 via a lifting cylinder. Specifically, the discharge pipe comprises a fixed pipe and a guide pipe. The fixed pipe is fixed to the outlet of the upper silo. One end of the guide pipe is hinged to the fixed pipe, and the other end is connected to the shield body of the U-shaped shield machine via a suspension, forming a floating discharge structure suitable for U-shaped shield construction.

[0094] Further, if Figure 19As shown, the spiral separator 43a includes a box-type trough body 34a, which is a long strip-shaped box body. The width of the box-type trough body corresponds to the width of the cushion layer safety zone to ensure the uniformity of the material discharge. A feed hopper 37a is provided in the middle of the box-type trough body 34a. The feed hopper is used to receive the cushion layer paving material flowing out of the discharge pipe. A number of discharge hoppers 38a are provided on the outer wall of the box-type trough body 34a. In this embodiment, the number of discharge hoppers can be set as needed. The multiple discharge hoppers are set at the same angle and at the same height to uniformly discharge the material in the spiral separator into the cushion layer safety zone. A spiral shaft 39a is provided inside the box-type trough body 34a for rotation. The spiral shaft 39a is connected to a driving member 310a provided on the box-type trough body 34a. The driving member 310a can be a hydraulic motor or an electric motor to provide power for the rotation of the spiral shaft. In this embodiment, the spiral shaft can be a solid shaft. To facilitate the uniform discharge of the material, the spiral blades on the left and right sections of the spiral shaft have opposite spiral directions. A movable baffle is provided between the discharge hopper 38a and the box-shaped trough body 34a. The movable baffle is slidably connected to the box-shaped trough body and moves up and down through a telescopic member to realize the opening and closing of the box-shaped trough body discharge port. The movable baffle can also adopt an electric gate valve to realize the opening and closing of its flow channel. A cover plate 31a corresponding to the discharge hopper 38a is provided on the top wall of the box-shaped trough body 34a. The cover plate is detachably connected to the box-shaped trough body by bolts, which is convenient for maintenance and anti-clogging. During operation, the motor drives the left and right spiral blades to rotate through the left and right spiral shafts, and evenly transports the material in the box-shaped trough body to several groups of left and right discharge ports. By controlling the opening and closing of several groups of movable baffles, the discharge volume is matched with the paving speed of the paver for efficient paving.

[0095] Furthermore, the spiral shaft 39a includes a left spiral shaft 32a and a right spiral shaft 33a arranged coaxially. The left spiral shaft 32a and the right spiral shaft 33a are connected by a self-aligning bearing 36a. The self-aligning bearing 36a is fixed in the box-shaped trough body 34a through a bearing seat. In this embodiment, the length of the left spiral shaft is equal to the length of the right spiral shaft. When the left and right rotating shafts are not concentric, the two shafts can be made concentric by adjusting the center self-aligning bearing between the two shafts. The spiral direction of the spiral blades on the left spiral shaft 32a is opposite to the spiral direction of the spiral blades on the right spiral shaft 33a, so that the material flows out evenly. The driving member 310a includes a left motor and a right motor. The left motor is connected to the left spiral shaft 32a, and the right motor is connected to the right spiral shaft 33a. The two spiral shafts are driven separately by two driving members, which can realize simultaneous or non-simultaneous discharging, partial discharging, and improve discharging flexibility.

[0096] Further, if Figure 20As shown, the cushion scraping mechanism 44a includes a support rail 4-1a located outside the spiral separator 43a. Lifting cylinders are installed at both ends of the support rail 4-1a, connecting it to the spiral separator or other fixed structures via the lifting cylinders. When the lifting cylinders are in a telescopic state, the lateral inclination angle of the support rail can be adjusted, and the overall height of the cushion scraping mechanism can also be adjusted to achieve paving of paving materials of varying thicknesses. A scraper assembly is slidably mounted on the support rail 4-1a, and the scraper assembly moves along the support rail 4-1a via a transverse transmission mechanism 45a. The transverse transmission mechanism is provided on the support rail, providing reciprocating motion for the scraper assembly along the support rail, thereby uniformly spreading the cushion paving material exiting the spiral separator laterally. The scraper assembly includes a sliding seat 4-3a mounted on a support rail 4-1a. A crossbeam 4-4a is hingedly connected to the sliding seat 4-3a. The crossbeam 4-4a is connected to the sliding seat 4-3a via an adjustment cylinder 4-5a. The adjustment cylinder allows the crossbeam to swing up and down relative to the sliding seat, adjusting its longitudinal inclination angle. A first scraper 4-6a is secured to the lower portion of the crossbeam 4-4a. Alternatively, a support rod 4-7a is secured to the side of the crossbeam 4-4a, with a pressure roller 4-8a attached to the support rod. The support rod also serves to reinforce the crossbeam. One support rod can be located on one side of the scraper, or two can be located on either side of the scraper. Pressure rollers are attached to the support rods to spread the paving material before scraping or to flatten it after scraping, improving paving quality. The support rail 4-1a is a rectangular frame structure; that is, it includes two parallel sliding beams, and the two ends of the sliding beams are fixed by connecting seats. An extension block 410a is detachably connected to the rectangular frame structure. Specifically, the support rail is a support rail with a variable diameter, such as Figure 22 As shown, the support rail frame specifically includes a left rail frame 411 a, a right rail frame 412 a and an extension block 410 a. The left rail frame 411 a and the right rail frame 412 a are detachably connected by the extension block 410 a. The overall length of the support rail frame can be changed by changing the number or size of the extension blocks to adapt to paving areas with different sections. As a preferred solution, the extension block 410 a is a U-shaped block to ensure a smooth transition connection with the left rail frame 411 a and the right rail frame 412 a. The sliding seat 4-3a is a concave-shaped seat, and the concave-shaped seat is in sliding contact with the rectangular frame structure, that is, the protruding portion of the concave-shaped seat is slidably matched with the two sliding beams respectively to form a two-point support, thereby improving the stability of the sliding seat. In order to ensure that the sliding seat can move more smoothly along the support rail frame, a rolling element is provided on the contact surface corresponding to the sliding seat 4-3a and the support rail frame 4-1a. The rolling element can be a ball or a roller.

[0097] like Figure 21As shown, the transverse transmission mechanism 45a includes a driving sprocket 51a rotatably arranged on one side of the support rail 4-1a and a driven sprocket 52a rotatably arranged on the other side of the support rail 4-1a. The driving sprocket 51a is connected to a driving motor 54a or a driving motor arranged on the support rail 4-1a. A transmission chain 53a is connected between the driving sprocket 51a and the driven sprocket 52a. The sliding seat 4-3a is fixed on the transmission chain 53a. Under the action of the driving motor or the driving motor, the sliding scraper 42 can slide left and right along the scraping device frame driven by the sprocket chain to achieve mechanized and automatic flattening of the material. A tensioner 55a that cooperates with the transmission chain 53a is provided on the support rail 4-1a. Figure 23 As shown, the tensioner 55a comprises a tensioning base 5-1 and a tensioning cylinder 5-2. The tensioning base 5-1 is fixed to the telescopic end of the tensioning cylinder 5-2, while the fixed end of the tensioning cylinder 5-2 is fixed to the support rail 4-1a via a support base 5-3. The tensioning base 5-1 is an arc-shaped base with an arc-shaped groove that mates with the drive chain 53a. During constant-section paving, the chain tensioning cylinder extends, and the tensioning base pulls the chain upward (the chain is contained within the tensioning base's groove (not shown)), ensuring proper chain tension and enabling sub-layer paving. During variable-section construction (e.g., widening), the chain tensioning cylinder retracts a certain distance, causing the tensioning base to fall back, ensuring proper chain tension and enabling variable-section sub-layer paving.

[0098] Example 7, a construction method using the aforementioned variable-diameter paving integrated U-shaped shield machine, comprises the following steps: S1: adjusting the width of the variable-diameter U-shaped shield frame 1 according to the cross-sectional width of the tunnel to be excavated, so that the outer profile of the variable-diameter U-shaped shield frame 1 meets the required channel cross-sectional dimensions. Specifically, by cooperating with the first, second, and third telescopic adjustment members, the widths of the front, middle, and rear shields are adjusted to meet the required width of the tunnel to be excavated.

[0099] S2: During the excavation process of the U-shaped shield machine, the paver spreads the cushion layer paving material in the paving area horizontally or vertically; during the excavation process of the U-shaped shield machine, the paver described in Example 5 is used for vertical paving, and the paver described in Example 6 is used for horizontal paving, so that the cushion layer in the paving area is paved flat.

[0100] S3: The pipe-erecting machine system 10 performs synchronous assembly of the pipe segments, i.e., the pipe-erecting machine begins to complete the lifting, flipping, and assembly of the pipe segments. After the assembly of the pipe segments is completed, long bolts are used to complete the tensioning between the pipe segments to ensure the stable connection of the pipe segments. The advance excavator 6 located in front of the U-shaped shield machine cooperates with the grouting support system 3 to prepare the fluidized solidified soil, and synchronously backfills the prepared mixed slurry into the fertilizer trough formed between the side wall of the pipe segment and the original soil, realizing synchronous fertilizer trough backfilling; that is, the quick-setting backfill soil medium is used to reinforce the periphery of the pipe segment to ensure the stability of the integrated pipeline corridor.

[0101] S4: Repeat steps S2 and S3 until the excavation and support of the entire channel are completed.

[0102] The process of the paver in step S2 uniformly paving the cushion paving material in the paving area in the horizontal direction is as follows: Figure 24 As shown, A1: A laser transmitter is installed at a suitable position behind the U-shaped shield machine. This laser transmitter corresponds to a laser receiver installed on the spiral separator, forming the U-shaped shield machine's guidance and control system. During construction, the laser generator is placed inside the assembled segments. The number of laser transmitters can be multiple as needed, specifically at least two. The receiver detects the position of the laser, determines whether the U-shaped shield's pitch and roll postures meet the elevation, and transmits the signal to the controller.

[0103] A2: When paving begins, the cushion paving material in the upper silo enters the spiral separator through the discharge pipe; then it is discharged through the discharge hopper of the spiral separator; specifically, a crane lifts the paving material into the upper silo, and the paving material is slid along several sections of the discharge pipe along the inclined chutes to the slag inlet of the spiral separator; after the box-type trough is filled with a certain amount of material, the material is stirred by the left and right spiral blades in the box-type trough and transported to several groups of left and right discharge ports respectively, and the material is finally spread to the ground by controlling the corresponding movable baffles near the discharge port.

[0104] A3: The laser receiver receives the laser emitted by the laser transmitter and determines the posture of the U-shaped shield machine. When the posture of the U-shaped shield machine is parallel to the ground elevation, the cushion layer scraping mechanism of the transverse cushion layer paver performs transverse reciprocating motion under the action of the transverse transmission mechanism to evenly spread the cushion layer paving material; that is, when the pitch and roll postures of the shield machine are parallel to the ground elevation, there is no need for the guide controller to issue instructions for adjustment, and the cushion layer scraping device paves and scrapes normally.

[0105] A4: When the posture of the U-shaped shield machine is not parallel to the ground elevation, the overall lateral inclination angle of the cushion scraping mechanism is adjusted by the lifting cylinder. The lateral inclination in this embodiment refers to the direction perpendicular to the excavation direction, so as to balance the non-parallelism of the shield machine's rolling posture; then the longitudinal inclination angle of the scraper of the cushion scraping mechanism is adjusted by the adjusting cylinder of the cushion scraping mechanism. The longitudinal inclination in this embodiment refers to the excavation direction, so as to balance the non-parallelism of the shield machine's pitch posture, so that the scraper of the cushion scraping mechanism is parallel to the ground elevation, and then the scraper of the cushion scraping mechanism performs lateral reciprocating motion under the action of the lateral transmission mechanism to evenly spread the cushion paving material, ensuring that the cushion paving material is spread evenly.

[0106] A5: When the cross-section of the paving area changes, variable-section paving is required; add extension blocks to the support rails of the cushion layer scraping mechanism to increase the overall length of the support rails to adapt to the variable-section paving area. At the same time, adjust the length of the transmission chain of the transverse transmission mechanism through the tensioner to ensure that the scraper of the cushion layer scraping mechanism can stably perform transverse reciprocating motion, so as to achieve uniform paving of the cushion layer paving material in the variable-section paving area; when the tensioner is paving at a constant cross-section, the chain tensioning cylinder extends and the tensioning seat pulls the chain upward to ensure the normal tensioning operation of the chain and realize the cushion layer paving function; when the cross-section is variable (such as widening), the chain tensioning cylinder needs to retract a certain stroke and the tensioning seat falls back to ensure the normal tensioning operation of the chain.

[0107] In step S2, the process of the paver uniformly paving the cushion paving material in the paving area longitudinally is as follows: B1: the U-shaped shield machine advances a certain distance in the excavation direction to provide construction space for the paver;

[0108] B2: The telescopic arm drives the spreading head in a reciprocating motion along the excavation direction, evenly spreading the cushion paving material longitudinally. Specifically, the telescopic arm consists of a fixed barrel section, a first telescopic arm, and a second telescopic arm. The telescopic speed is controlled by a hydraulic cylinder. When paving the cushion layer, the telescopic arm is extended at a uniform speed by activating a switch button, providing extension movement for the telescopic arm. When extended to the set position, the telescopic arm stops moving. The dynamic hopper assembly controls the switch, and the drive device drives the material diverter shaft within the hopper. The hopper adopts a U-shaped trough. Before each paving operation, a sufficient amount of cushion material is pre-loaded into the hopper. The drive roller ensures a constant amount of material is spread per rotation. The discharge speed is adjusted by adjusting the telescopic arm speed, ensuring an even distribution of material. By extending the lifting cylinder to the designed elevation, the cushion material is pre-adjusted for leveling. When the requirements are met, the telescopic arm retracts at the designed speed to achieve retraction at a uniform speed, providing a retraction movement for the telescopic arm, forming a hopper that spreads material and leveled the material at the same time. The leveling is synchronized with a laser leveling device, which feeds back the signal to the control system through the CAN bus through the laser receiving device, lifting the cylinder, and performing synchronous leveling to ensure the accuracy of cushion paving.

[0109] B3: When the cross-section of the paving area changes, change the position and number of the paver on the variable diameter U-shaped shield so that the spreading head can cover the entire paving area, and realize uniform paving of the cushion paving material in the variable cross-section paving area. After the paving of one ring of pipe segments is completed, when the telescopic arm telescopic cylinder retracts to the set position, the telescopic arm stops, the material feeding shaft drive device of the hopper assembly stops, the hopper stops dropping materials, and at the same time, the scraper is lifted upward to the upper limit by the scraper lifting cylinder to avoid the shield structure. The telescopic arm continues to retract to the initial position, and the entire device is retracted into the shield body to carry out the hoisting of the next ring of pipe corridors. Through the above invention, the efficiency of cushion construction in U-shield construction can be improved by more than 50% compared with the traditional construction plan, which greatly improves the adaptability of the U-shield construction method.

[0110] The specific process of backfilling the fertilizer tank in step S3 is as follows:

[0111] S3.1 Preparation of fluidized solidified soil: The excavator sends the excavated soil directly or after drying it into the screening and crushing device, which crushes and screens the soil. The screened part of the soil enters the stirring device in a certain proportion, and the admixture container, curing agent container and water tank simultaneously add a certain proportion of admixture, curing agent and water into the stirring device; then the stirring device stirs the materials therein to form fluidized solidified soil; the amount of fluidized solidified soil in the stirring device at least meets the backfill requirement of one ring of pipe segments; when the displayed weight increase reaches a kilogram, stop injecting water; the excavator sends the excavated soil directly or after drying it into the soil screening and crushing device, which screens the original soil, and the soil with the required particle size is sent to the stirring device for stirring. If b kilograms of soil are required, stop adding soil when the weighing function of the stirring device displays a weight increase of b kilograms. Open the connecting valves between the curing agent container, the bottom of the additive container, and the stirring device, and inject a fixed amount of material into the stirring device. For example, the fluidized solidifying soil required to fill the gap in a pipe segment consists of x kg of curing agent, y kg of additives, and other materials. Open the valve of the material container, and the material will fall into the stirring device. When the weighing function indicates that the dropped weight has reached x kg and y kg, close the valve, and the material injection is complete. The stirring device then stirs the mixture for a predetermined period of time, thus preparing the fluidized solidifying soil required to fill the gap behind the wall of a pipe segment. After the materials are added, the curing agent container and additive container at the top will be missing material. While the stirring device is stirring, the curing agent container and additive container can be refilled with material to prepare for the next addition.

[0112] S3.2 Grouting: The admixture and the fluidized solidified soil prepared in step S1 are separately pumped into the three-way mixer of the grouting system. After mixing, a mixed slurry is formed. The mixed slurry is pumped to the rear of the shield tail sealing system through the slurry mixing pipeline for fertilizer tank backfilling. Specifically, while the U-shaped shield machine advances forward, the prepared fluidized solidified soil and water glass are separately pumped into the grouting mixer to be fully mixed. The role of water glass is to reduce the solidification time of the fluidized solidified soil. After the two are mixed, they pass through the pipeline to the grouting port and are grouted into the wall. When the U-shaped shield machine advances to the width of a pipe segment, it stops and the pipe segment is laid. At this time, the fluidized solidified soil after grouting is waiting to solidify. The fluidized solidified soil preparation system begins to prepare the fluidized solidified soil required for the next pipe segment. When the pipe segment is laid, the fluidized solidified soil has also solidified, and the fluidized solidified soil required for the next pipe segment has been mixed in the mixing device. The U-shield machine advances again, and the pumping equipment again extracts the fluidized solidified soil and water glass to mix and grout, and the process continues in this cycle. In addition, as a technical solution for grouting process modification, water glass can be directly injected into the mixing device through an admixture container. After the fluidized solidified soil and water glass are fully mixed, they are pumped together and injected into the wall, eliminating the need for a grouting mixer.

[0113] S3.3 Sealing: While grouting is being performed in step S2, the shield tail sealing system will synchronously seal the mixed slurry to prevent the slurry from flowing back to the tail shield.

[0114] S3.4: Repeat steps S1 to S3 until all segments are assembled.

[0115] The specific process of step S3.3 includes two working conditions: injecting the mixed slurry into the fertilizer tank while pushing forward and backfilling the mixed slurry into the fertilizer tank after pushing forward is completed;

[0116] The specific process of injecting the mixed slurry into the fertilizer tank while advancing is as follows: when one pipe section is laid, the mixed slurry has solidified, and the preparation of the fluidized solidified soil required for the next pipe section is also completed in the mixing device; the U-shaped shield machine continues to advance forward, and the grouting system continues to inject the mixed slurry into the fertilizer tank after advancement, and the work cycle is repeated.

[0117] The specific process of backfilling the slurry mixture into the fertilizer tank after the advancement is completed is as follows: when one pipe section is laid and before the U-shaped shield machine starts the next ring advancement, the mixed slurry has not yet solidified, and the sealing push plate of the tail sealing system is pressed backward against the already laid pipe section; the thrust cylinder pushes the shield machine forward, and the push plate is stationary relative to the pipe section; after the thrust cylinder is advanced, the mixed slurry can solidify, and then the sealing push plate is retracted, and the mixed slurry is injected into the fertilizer tank after advancement, and the cycle continues. In other words, the thrust cylinder retracts and starts filling with fluidized solidified soil and lowering the pipe section at the same time. As a result, after the pipe section is lowered, the fluidized solidified soil has not yet solidified, so it can only be advanced first, and then the thrust cylinder and sealing push plate are retracted after the advancement is completed; this buys time for the mixed slurry to solidify, while not delaying the U-shaped shield machine's excavation construction, further improving construction efficiency.

[0118] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A U-shaped shield machine with a variable diameter and integrated paving system, comprising a pipe erecting machine system (10) and a U-shaped tunneling machine, characterized in that: The U-shaped tunneling machine includes a variable diameter U-shaped shield (1), a knife-inserting edge cleaning mechanism (2) is provided at the front of the variable diameter U-shaped shield (1), a grouting support system (3) is integrated in the front shield of the variable diameter U-shaped shield (1), and a paver (4) and a jacking system (5) are provided at the rear of the variable diameter U-shaped shield (1); The variable diameter U-shaped shield frame (1) comprises a front shield (1-1), a middle shield (1-2) and a tail shield (1-3), wherein the front shield (1-1), the middle shield (1-2) and the tail shield (1-3) are all split shield bodies; the front portion of the middle shield (1-2) is connected to the front shield (1-1) via a hinged oil cylinder (1-4), the rear portion of the middle shield (1-2) is fixedly connected to the tail shield (1-3), and the blade-inserting edge-clearing mechanism (2) is arranged at the front end of the front shield (1-1); The blade edge clearing mechanism (2) is a telescopic blade; the front shield (1-1) and the middle shield (1-2) are assembled into a three-piece structure to form a U-shaped shield body, and the tail shield (1-3) is assembled into a two-piece structure to achieve a change in the width of the variable diameter U-shaped shield frame (1); under normal circumstances, the widths of the front shield, the middle shield and the tail shield are adjusted synchronously to adapt to the excavation of the variable diameter section; the front shield, the middle shield and the tail shield can also be adjusted in width in different proportions to achieve small diameter turning excavation; The grouting support system (3) includes a fluidized solidified soil preparation system (31), a shield tail sealing system (32) and a grouting system (33). The shield tail sealing system (32) is detachably connected to the shield tail. The fluidized solidified soil preparation system (31) includes a drying device (31-1), a screening and crushing device (31-2) and a stirring device (31-3) integrated in the front shield. The drying device (31-1), the screening and crushing device (31-2) and the stirring device (31-3) are connected in sequence. The stirring device (31-3) is connected to an additive container (31-4), a curing agent container (31-5) and a water tank (31-6). The output end of the stirring device (31-3) is connected to the inlet end of the grouting system (33) and extends backward to the shield tail sealing system (32). Under the action of the grouting system, the fluidized solidified soil is poured into the gap between the side wall of the pipe segment and the original soil, and the excavated soil is used to backfill the fertilizer trough. The paver (4) is a paving device for horizontal paving, and performs horizontal paving of the paving material in the paving area; or the paver (4) is a paving device for longitudinal paving, and performs longitudinal paving of the paving material in the paving area; During horizontal paving, the paver (4) includes an upper hopper (41a) and a spiral separator (43a), the upper hopper (41a) is connected to the spiral separator (43a) through a discharge pipe (42a), and a cushion scraping mechanism (44a) capable of moving up and down is provided on the discharge side of the spiral separator (43a), and the cushion scraping mechanism (44a) moves laterally along the spiral separator (43a) under the action of a transverse transmission mechanism (45a); the discharge pipe (42a) is connected to a variable diameter U-shaped shield frame (1) through a suspension member, and the cushion scraping mechanism (44a) is connected to the tail shield of the variable diameter U-shaped shield frame (1) through a lifting cylinder to form a floating discharge structure; the scraper member of the cushion scraping mechanism performs transverse reciprocating motion under the action of the transverse transmission mechanism, thereby achieving efficient transverse paving; The cushion layer scraping mechanism (44a) comprises a support rail (4-1a) located outside the spiral separator (43a), with lifting cylinders provided at both ends of the support rail (4-1a), a scraper assembly slidingly provided on the support rail (4-1a), and the scraper assembly moving along the support rail (4-1a) via a transverse transmission mechanism (45a); the scraper assembly comprises a sliding seat (4-3a) provided on the support rail (4-1a), a crossbeam (4-4a) hingedly connected to the sliding seat (4-3a), the crossbeam (4-4a) being connected to the sliding seat (4-3a) via an adjusting cylinder (4-5a), and a first scraper (4-6a) being fixed to the lower portion of the crossbeam (4-4a); a support rod (4-7a) being fixed to the side of the crossbeam (4-4a), and a pressure roller (4-8a) being provided on the support rod (4-7a).

2. The variable-diameter paving integrated U-shaped shield machine according to claim 1, characterized in that: The front shield (1-1) and the middle shield (1-2) both comprise a left block (101), a right block (102), a bottom block I (103) and a bottom block II (104); the left block (101) and the right block (102) are respectively connected to the bottom block I (103) and the bottom block II (104) to form a U-shaped shield body; a first telescopic adjustment member is provided between the left block (101) and the right block (102); and a second telescopic adjustment member is provided between the bottom block I (103) and the bottom block II (104).

3. The variable-diameter paving integrated U-shaped shield machine according to claim 2, characterized in that: The first telescopic adjustment member comprises a basic block (105) respectively fixed on the left block body (101) and the right block body (102), and a standard block (106) is detachably provided between the basic blocks (105); the second telescopic adjustment member comprises an amplitude modulation cylinder (107) and / or an amplitude modulation block (108) arranged between the bottom block I (103) and the bottom block II (104), and the amplitude modulation block (108) is detachably connected to the bottom block I (103) and the bottom block II (104).

4. The variable-diameter paving integrated U-shaped shield machine according to claim 2, characterized in that: The first telescopic adjustment member comprises an inner sleeve (101a) fixed on the left block body (101) and an outer sleeve (102a) fixed on the right block body (102), the inner sleeve (101a) being sleeved in the outer sleeve (102a), and the inner sleeve (101a) and the inner portion of the outer sleeve (102a) are connected via a first oil cylinder; the second telescopic adjustment member comprises a passive wedge (103a) respectively fixed on the bottom block I (103) and the bottom block II (104), an active wedge (104a) being slidably fitted between the two passive wedges (103a), the active wedge (104a) being fixed via a positioning bolt, and a sleeve member (105a) being further provided between the bottom block I (103) and the bottom block II (104).

5. The variable-diameter paving integrated U-shaped shield machine according to claim 2, 3 or 4, characterized in that: The tail shield (1-3) comprises a left shield body (301) and a right shield body (302), and a third telescopic adjustment member is provided between the left shield body (301) and the right shield body (302).

6. The variable-diameter paving integrated U-shaped shield machine according to claim 5, characterized in that: The third telescopic adjustment member comprises a left-handed screw (303) fixed on the left shield body (301) and a right-handed screw (304) fixed on the right shield body (302), wherein the left-handed screw (303) is connected to the right-handed screw (304) via a screw sleeve (305).

7. The variable diameter paving integrated U-shaped shield machine according to any one of claims 1 to 4 and 6, characterized in that: The shield tail sealing system (32) includes a tail shield mounting plate (2-1), two sealing structures are arranged on the tail shield mounting plate (2-1) in front and back along the shield machine excavation direction, and a pad (2-2) is arranged between the two adjacent sealing structures; the front sealing structure is a polyurethane plate (2-3), and the rear sealing structure is a rubber plate (2-4); a reinforcing plate (2-5) is provided at the connection between the polyurethane plate (2-3) and the rubber plate (2-4) and the tail shield mounting plate (2-1); each sealing structure includes a left seal (21), a right seal (22) and a bottom seal (23), and the left seal (21), the right seal (22) and the bottom seal (23) form a sealing cavity structure with an upper opening.

8. The variable-diameter paving integrated U-shaped shield machine according to claim 7, characterized in that: When the U-shaped shield machine is pushed forward and the mixed slurry is backfilled into the fertilizer tank, the shield tail sealing system (32) further includes a sealing push plate (24), which is connected to the middle shield or the tail shield through a push cylinder (25) of an axially arranged push system (5); and the tail shield mounting plate (2-1) is mounted on the axial tail of the sealing push plate (24).

9. The variable-diameter paving integrated U-shaped shield machine according to claim 8, characterized in that: The grouting system (33) includes a three-way mixer (33-1), one inlet of the three-way mixer (33-1) is connected to a fluid solidification soil pipe (33-2) connected to the output end of the stirring device (31-3), and the other inlet is connected to an admixture pipeline (33-3); the outlet end of the three-way mixer (33-1) is connected to a slurry mixing pipeline (33-4), and the liquid outlet of the slurry mixing pipeline (33-4) extends to the rear of the shield tail sealing system (32); and flow meters are provided on the fluid solidification soil pipe (33-2), the admixture pipeline (33-3), and the slurry mixing pipeline (33-4).

10. The variable-diameter paving integrated U-shaped shield machine according to claim 9, characterized in that: It also includes an advance excavator (6), which corresponds to the fluidized solidified soil preparation system (31); and a weighing mechanism is provided in the stirring device (31-3).

11. The U-shaped shield machine with variable diameter and integrated paving according to any one of claims 1 to 4, 6, and 8 to 10, characterized in that: The paver (4) comprises a telescopic arm (41) and a material spreading head arranged at the shield position of a variable-diameter U-shaped shield frame (1); the material spreading head is located at the telescopic front end of the telescopic arm (41); the material spreading head comprises a hopper assembly (42) and a scraper assembly (43); the scraper assembly (43) is located outside the hopper assembly (42).

12. The variable diameter paving integrated U-shaped shield machine according to claim 11, characterized in that: The telescopic arm (41) comprises a fixed barrel section (11), a first telescopic arm (12) and a second telescopic arm (13); a first telescopic oil cylinder (14) is connected between the fixed barrel section (11) and the first telescopic arm (12); the first telescopic arm (12) is telescoped relative to the fixed barrel section (11) under the action of the first telescopic oil cylinder (14); a second telescopic oil cylinder (15) is connected between the first telescopic arm (12) and the second telescopic arm (13); the second telescopic arm (13) is telescoped relative to the first telescopic arm (12) under the action of the second telescopic oil cylinder (15); wear-resistant blocks (111) are provided inside the fixed barrel section (11) and the first telescopic arm (12); a first connecting member (18) for connecting to the hopper assembly (42) and a second connecting member (19) for connecting to the scraper assembly (43) are provided at the front of the second telescopic arm (13).

13. The variable diameter paving integrated U-shaped shield machine according to claim 12, characterized in that: The hopper assembly (42) includes a hopper (420), the bottom of the hopper (420) is an arc-shaped bottom, a material drop opening (421) is provided on the arc-shaped bottom, a material shifting shaft (422) is provided inside the hopper (420), and the material shifting shaft (422) is connected to a driving device provided outside the hopper (420); the bottom of the hopper (420) is an arc-shaped bottom formed by two arc-shaped plates (426), the material drop opening (421) is located between the two arc-shaped plates (426), and the material shifting shaft (422) is located inside the arc-shaped bottom and corresponds to the arc-shaped bottom.

14. The variable diameter paving integrated U-shaped shield machine according to claim 13, characterized in that: The material-dispensing shaft (422) comprises a main shaft (22-1) and a scraper plate (22-2) fixed on the main shaft. The number of the scraper plates (22-2) is at least two and they are arranged on the main shaft (22-1) at equal angles. Connecting shaft heads are provided at both ends of the main shaft (22-1). The connecting shaft head at one end is connected to the driving device, and the connecting shaft head at the other end is rotatably connected to the hopper wall of the hopper (420).

15. The variable diameter paving integrated U-shaped shield machine according to claim 14, characterized in that: The scraper assembly (43) comprises a scraper beam (431) and a second scraper (433). Both ends of the scraper beam (431) are provided with vertically arranged lifting cylinders (432). The second scraper (433) is arranged at the telescopic ends of the two lifting cylinders (432). The second scraper (433) is an arc-shaped scraper. The lifting cylinder (432) is fixed to the scraper beam (431) via a cylinder clamp (434). A laser receiver (435) is provided on the upper part of the scraper beam (431).

16. The U-shaped shield machine with variable diameter and integrated paving according to any one of claims 1 to 4, 6, and 8 to 10, characterized in that: The spiral separator (43a) includes a box-shaped trough body (34a), a feed hopper (37a) is provided in the middle of the box-shaped trough body (34a), a plurality of discharge hoppers (38a) are provided on the outer wall of the box-shaped trough body (34a), a spiral shaft (39a) is provided inside the box-shaped trough body (34a), and the spiral shaft (39a) is connected to a driving member (310a) provided on the box-shaped trough body (34a); a movable baffle is provided between the discharge hopper (38a) and the box-shaped trough body (34a), and a cover plate (31a) corresponding to the discharge hopper (38a) is provided on the top wall of the box-shaped trough body (34a).

17. The variable diameter paving integrated U-shaped shield machine according to claim 16, characterized in that: The spiral shaft (39a) includes a left spiral shaft (32a) and a right spiral shaft (33a) arranged coaxially, the left spiral shaft (32a) and the right spiral shaft (33a) being connected via a self-aligning bearing (36a), the self-aligning bearing (36a) being fixed in the box-shaped trough body (34a) via a bearing seat, the spiral direction of the spiral blade on the left spiral shaft (32a) being opposite to the spiral direction of the spiral blade on the right spiral shaft (33a); the driving member (310a) includes a left motor and a right motor, the left motor being connected to the left spiral shaft (32a), and the right motor being connected to the right spiral shaft (33a).

18. The variable diameter paving integrated U-shaped shield machine according to claim 17, characterized in that: The support rail frame (4-1a) is a rectangular frame structure; an extension block (410a) is detachably connected to the rectangular frame structure; the sliding seat (4-3a) is a concave-shaped seat, the concave-shaped seat is in sliding contact with the rectangular frame structure, and rolling elements are provided on the contact surfaces corresponding to the sliding seat (4-3a) and the support rail frame (4-1a).

19. The variable diameter paving integrated U-shaped shield machine according to claim 18, characterized in that: The transverse transmission mechanism (45a) comprises a driving sprocket (51a) rotatably arranged on one side of the support rail frame (4-1a) and a driven sprocket (52a) rotatably arranged on the other side of the support rail frame (4-1a); the driving sprocket (51a) is connected to a driving motor (54a) or a driving motor arranged on the support rail frame (4-1a); a transmission chain (53a) is connected between the driving sprocket (51a) and the driven sprocket (52a); and the sliding seat (4-3a) is fixed on the transmission chain (53a); and a tensioner (55a) is provided on the support rail frame (4-1a) and is matched with the transmission chain (53a).

20. The variable-diameter paving integrated U-shaped shield machine according to claim 19, characterized in that: The tensioner (55a) comprises a tensioning seat (5-1) and a tensioning oil cylinder (5-2); the tensioning seat (5-1) is fixed to the telescopic end of the tensioning oil cylinder (5-2); the fixed end of the tensioning oil cylinder (5-2) is fixed to the support rail frame (4-1a) via a support seat (5-3); the tensioning seat (5-1) is an arc-shaped seat, and an arc-shaped groove is provided on the arc-shaped seat to match the transmission chain (53a).

21. The U-shaped shield machine with variable diameter and integrated paving according to any one of claims 1 to 4 and 18 to 20, characterized in that: The pipe crane system (10) comprises a gantry frame, the forward end of the gantry frame is detachably connected to a variable diameter U-shaped shield frame (1), the driven end of the gantry frame is provided with a traveling wheel, and the gantry frame is provided with a pipe segment sling (9).

22. A construction method for a variable-diameter paving integrated U-shaped shield machine, characterized by: Using the variable diameter paving integrated U-shaped shield machine according to claim 21, the steps are as follows: S1: According to the cross-sectional width of the tunnel to be excavated, the width of the variable diameter U-shaped shield (1) is adjusted so that the outer contour of the variable diameter U-shaped shield (1) meets the channel cross-sectional dimension requirements; S2: During the tunneling process of the U-shield machine, the paver spreads the cushion paving material in the paving area horizontally or vertically; S3: The pipe erection machine system (10) performs synchronous assembly of the pipe segments, and the advance excavator (6) located in front of the U-shaped shield machine cooperates with the grouting support system (3) to prepare the fluidized solidified soil, and synchronously backfills the prepared mixed slurry into the fertilizer trough formed between the side wall of the pipe segment and the original soil, thereby achieving synchronous fertilizer trough backfilling; S4: Repeat steps S2 and S3 until the excavation and support of the entire channel are completed.

23. The construction method of a variable-diameter paving integrated U-shaped shield machine according to claim 22, characterized in that: In step S2, the process of the paver uniformly paving the cushion paving material in the paving area in the transverse direction is as follows: A1: a laser transmitter is set up at a suitable position behind the U-shaped shield machine, and the laser transmitter corresponds to the laser receiver set on the spiral separator; A2: When paving begins, the cushion paving material in the upper silo enters the spiral separator through the discharge pipe; then it is discharged through the discharge hopper of the spiral separator; A3: The laser receiver receives the laser light from the laser transmitter and determines the position of the U-shaped shield machine. When the U-shaped shield machine is parallel to the ground elevation, the cushion layer scraping mechanism of the transverse cushion layer paver performs transverse reciprocating motion under the action of the transverse transmission mechanism, and the cushion layer paving material is evenly spread. A4: When the U-shaped shield machine is not parallel to the ground elevation, the overall lateral inclination angle of the cushion scraping mechanism is adjusted by the lifting cylinder, and then the longitudinal inclination angle of the scraper of the cushion scraping mechanism is adjusted by the adjustment cylinder of the cushion scraping mechanism to make the scraper of the cushion scraping mechanism parallel to the ground elevation. Then, the scraper of the cushion scraping mechanism performs a lateral reciprocating motion under the action of the lateral transmission mechanism to evenly spread the cushion paving material. A5: When the cross-section of the paving area changes, variable-section paving is required; add extension blocks to the support rails of the cushion layer scraping mechanism to increase the overall length of the support rails to adapt to the variable-section paving area. At the same time, adjust the length of the transmission chain of the transverse transmission mechanism through the tensioner to ensure that the scraper of the cushion layer scraping mechanism can stably perform transverse reciprocating motion, so as to achieve uniform paving of the cushion layer paving material in the variable-section paving area.

24. The construction method of a variable-diameter paving integrated U-shaped shield machine according to claim 23, characterized in that: In step S2, the process of the paver uniformly paving the cushion paving material in the paving area longitudinally is as follows: B1: the U-shaped shield machine advances a certain distance in the excavation direction to provide construction space for the paver; B2: The telescopic arm drives the spreading head to move back and forth along the excavation direction, spreading the cushion paving material evenly in the longitudinal direction; B3: When the cross-section of the paving area changes, change the position and number of the paver on the variable diameter U-shaped shield so that the spreading head can cover the entire paving area and achieve uniform paving of the cushion paving material in the variable cross-section paving area.

25. The construction method of a variable-diameter paving integrated U-shaped shield machine according to any one of claims 22 to 24, characterized in that: The specific process of backfilling the fertilizer tank in step S3 is as follows: S3.1 Preparation of fluidized solidified soil: The excavator delivers the excavated soil directly or after drying to the screening and crushing device. The screening and crushing device crushes and screens the soil. The screened portion of the soil is fed into the mixing device in a certain proportion. The admixture container, curing agent container, and water tank simultaneously add a certain proportion of admixture, curing agent, and water to the mixing device. The mixing device then stirs the materials therein to form fluidized solidified soil. The amount of fluidized solidified soil in the mixing device must meet the backfill requirements of at least one ring of pipe segments. S3.2 Grouting: The admixture and the fluidized solidified soil prepared in step S1 are pumped into the three-way mixer of the grouting system respectively to form a mixed slurry. The mixed slurry is pumped through the mixing pipeline to the rear of the shield tail sealing system for backfilling the fertilizer tank; S3.3 Sealing: While grouting in step S2, the shield tail sealing system synchronously seals the mixed slurry to prevent the slurry from flowing back to the tail shield; S3.4: Repeat steps S1 to S3 until all segments are assembled.

26. The construction method of a variable-diameter paving integrated U-shaped shield machine according to claim 25, characterized in that: The specific process of step S3.3 includes two working conditions: injecting the mixed slurry into the fertilizer tank while pushing forward and backfilling the mixed slurry into the fertilizer tank after pushing forward is completed; The specific process of injecting the mixed slurry into the fertilizer tank while advancing is as follows: when one pipe section is laid, the mixed slurry has solidified, and the fluidized solidified soil required for the next pipe section has been prepared in the mixing device; the U-shaped shield machine continues to advance forward, and the grouting system continues to inject the mixed slurry into the fertilizer tank after advancing, and the cycle continues; The specific process of backfilling the mixed slurry into the fertilizer tank after the advancement is completed is as follows: when one section of the pipe is laid and before the U-shaped shield machine starts to advance the next ring, the mixed slurry has not yet solidified, and the sealing push plate of the tail sealing system is pressed backward on the laid pipe section; the thrust cylinder pushes the shield machine forward, and the push plate is stationary relative to the pipe section; after the thrust cylinder completes the advancement, the mixed slurry can solidify, and then the sealing push plate is retracted, and the mixed slurry is injected into the fertilizer tank after advancement, and the cycle continues.

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