Construction method for shield tunneling machine launching

Abstract

The construction method specifically comprises the following steps that after a main machine of the shield tunneling machine is assembled in a well, a counter-force frame and a reference ring are installed; a negative ring is installed, when the negative ring is installed, a main machine of the shield tunneling machine pushes out three pipe pieces from the third o'clock position to the ninth o'clock position to form a half-ring assembled negative eighth ring, then the three pipe pieces continue to be pushed out to be assembled on the rear side of the negative eighth ring to form a half-ring assembled negative seventh ring, and a negative sixth ring, a negative fifth ring, a negative fourth ring, a negative third ring, a negative second ring and a negative first ring are sequentially assembled through the same method; then a zero ring is assembled between the shield tunneling machine main machine and the negative 1 ring in a full-ring mode, and negative ring installation is completed; then the shield tunneling machine main machine conducts tunneling for the first time; a first trolley on the ground is hoisted to the underground and then connected with a shield tunneling machine main machine for primary transfer tunneling; and finally, the No.2 to No.6 trolleys on the ground are hoisted to the underground and are sequentially connected with the No.1 trolley, and secondary transfer tunneling is carried out. The construction method disclosed by the invention can effectively reduce the construction cost and shorten the construction period.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel construction methods, and in particular relates to a construction method initiated by a shield machine. Background Art

[0002] In the current tunnel construction, the shield method has become the preferred method of tunnel construction in various construction fields due to its safety, high efficiency, high degree of automation, and low impact on the surrounding environment. The shield method construction technology can be divided into three construction stages: starting, interval advancement, and arrival. Among them, the shield starting operation is a difficult point in the shield method construction. During the shield method tunnel construction, the shield is started through the ventilation shaft or working shaft; the length of the starting shaft during the normal shield machine starting operation must be greater than the overall length of the shield machine. The shield machine can be assembled in sections or blocks on the ground and then hoisted into the shaft for assembly to carry out the overall starting advancement construction.

[0003] In the actual construction process, due to the limitations of site conditions, the total length of the starting shaft is often less than the total length of the shield machine. The existing method often adopts the rear guide tunnel method for construction, that is, based on the original starting length of the starting shaft, a guide tunnel is secretly dug backwards, and then the rear supporting trolley is placed in the rear guide tunnel for starting.

[0004] The above-mentioned post-pilot tunnel method has high requirements on geological conditions. First of all, the post-pilot tunnel method is not suitable for all types of rock and soil. Under poor geological conditions, the construction difficulty and risk will increase significantly. Moreover, the actual construction of the post-pilot tunnel method involves multiple processes, such as pilot tunnel excavation, initial support, secondary lining, etc. Therefore, the post-pilot tunnel method will greatly increase the construction cost and extend the overall construction period. Summary of the invention

[0005] The purpose of the invention is to provide a construction method for starting a shield machine, which solves the problems of high cost and long construction period existing when the shield machine adopts the rear guide tunnel method for starting.

[0006] The technical solution adopted by the present invention is a construction method initiated by a shield machine, comprising:

[0007] The shield machine mainframe is lowered into the well for assembly, and then the reaction frame and reference ring are installed;

[0008] Install the negative ring. When installing the negative ring, the shield machine mainframe pushes out three segments from the 3 o'clock position to below the 9 o'clock position in the assembly mode. The three segments contact the lower part of the reaction frame to form a negative 8 ring of semi-ring assembly. Then continue to push out three segments to assemble on the rear side of the negative 8 ring to form a negative 7 ring of semi-ring assembly. Use the same method to assemble the negative 6 ring, negative 5 ring, negative 4 ring, negative 3 ring, negative 2 ring and negative 1 ring in sequence on the rear side of the negative 7 ring. When assembling the semi-ring, ensure that the width of the upper opening of the segment is greater than the width of the equipment bridge. Then assemble the 0 ring between the shield machine mainframe and the negative 1 ring and complete the installation of the negative ring.

[0009] The shield machine mainframe made its first excavation;

[0010] After hoisting the No. 1 trolley on the ground to the underground, it is connected to the shield machine host and a transfer excavation is carried out;

[0011] The No. 2 to No. 6 trolleys on the ground were hoisted into the underground and connected with the No. 1 trolley in turn for secondary transfer excavation. After the secondary transfer excavation was completed, the whole machine excavated normally.

[0012] Preferably, after the negative ring is installed, steel supports are symmetrically arranged along the axis of the negative ring to form an axial support system. When installing the axial support system, the upper part of the negative ring is connected to the upper part of the reaction frame.

[0013] Preferably, four steel pipes are used when installing the axial support system. The four steel pipes are distributed on both sides in groups of two, and a downhole passage is left in the middle to allow the trolley to pass through.

[0014] Preferably, the assembly of the shield machine main unit downhole specifically includes the following steps:

[0015] The shield base is installed, and then the middle shield, front shield, cutter head, assembler and tail shield are hoisted into the well and installed on the shield base.

[0016] Preferably, installing the reaction frame and the reference ring specifically includes the following steps:

[0017] First, hoist the lower beam of the reaction frame into the well for assembly, then hoist the side beam and the upper part of the reaction frame into the well and assemble them together with the lower beam;

[0018] Lift the lower half of the reference ring into the well and connect it to the lower crossbeam of the reaction frame. Then lift the upper half of the reference ring and connect it to the upper part of the reaction frame and the lower half of the reference ring respectively. Ensure that the center of the reference ring coincides with the center of the reaction frame and assemble the two.

[0019] The reaction frame is adjusted in the horizontal and axial directions so that the center lines of the reaction frame and the reference ring are consistent with the axis of the tunnel, and finally the reaction frame is welded and fixed.

[0020] Preferably, when installing the reaction frame, a double-jointed H35 steel welding system is used for support between the reaction frame and the main structure of the launching shaft.

[0021] Preferably, lubricating oil is applied to the tunneling track surface when the shield machine main machine is tunneling for the first time.

[0022] Preferably, the foam pipe and hydraulic pipe in the extension pipeline need to be removed before hoisting the No. 1 trolley for the single-transfer excavation, and then the equipment bridge and the No. 1 trolley are hoisted to enter the tunnel. The excavation distance during the single-transfer excavation is the total length of the shield machine main unit.

[0023] Preferably, a slag outlet is installed behind trolley No. 1 during a single transfer excavation, and a temporary belt conveyor is installed at the same time, and the slag is discharged from the slag outlet of trolley No. 1.

[0024] Preferably, after one-time transfer excavation is completed, all extension pipelines are removed and hoisted to the ground, trolleys No. 2 to No. 6 are hoisted into the tunnel, and trolleys No. 2 to No. 6 are connected to the rear side of trolley No. 1 in sequence, and then the whole machine excavates normally.

[0025] The beneficial effects of the present invention are:

[0026] The present invention discloses a construction method for starting a shield machine. When installing negative ring segments between a reaction frame and a main machine of the shield machine, only three segments on the lower side (i.e., three standard blocks below the 3 o'clock position to the 9 o'clock position) are pushed out to connect between the reaction frame and the main machine of the shield machine to form a semi-ring starting system to provide reaction force. The upper part of the negative ring formed by the semi-ring assembly has sufficient space, so that the circulating materials for starting the shield machine can be quickly lowered into the well. In addition, the method is subsequently started by splitting, that is, the split starting is performed by adopting the method of single main machine excavation of the shield machine + secondary transfer. During the split starting, the main machine part of the shield machine is hoisted and assembled separately from the subsequent supporting trolley, which can significantly reduce the space required underground. In addition, because the split starting allows part of the equipment to be assembled in the starting well first, and then the subsequent assembly is performed, the overall assembly complexity can be reduced and the assembly time can be simultaneously reduced. During the split starting process, the slag transportation and the circulating materials can be vertically transported from the space on the upper side of the negative ring when hoisting. In summary, the method for split starting of the shield machine disclosed in the present invention can effectively reduce costs and shorten the construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flow chart of the main inventive points of a construction method initiated by a shield machine of the present invention;

[0028] Figure 2 It is an overall flow chart of a construction method initiated by a shield machine of the present invention;

[0029] Figure 3 It is a schematic diagram of a shield machine-starting construction method after the negative ring is installed. DETAILED DESCRIPTION

[0030] The present invention is described in detail below in conjunction with the accompanying drawings and specific implementation methods. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection solution of the present invention.

[0031] The invention discloses a shield machine-starting construction method, which specifically comprises the following steps:

[0032] Preparation before excavation: The shield machine mainframe is lowered into the well for assembly. After assembly, the reaction frame and reference ring are installed. After completion, the tunnel door is sealed. Finally, the supporting trolley is placed on the ground. The pipeline is extended down the well to connect the supporting trolley with the shield machine mainframe. After the connection is completed, the equipment is debugged;

[0033] Before the shield machine is lowered into the well, the spatial position of the starting base is calculated according to the tunnel design axis, the portal position and the size of the shield machine. The position of the shield base is accurately laid out according to the actual measurement results. During installation, it is hoisted into the well and welded in place according to the measured and laid-out baseline. The two track center lines on the base are placed equidistantly and parallel to the tunnel design axis, and the elevation of the base track is ensured to ensure that the shield machine head is aligned with the center of the portal. After the base position is remeasured, H-shaped steel cross supports are welded around the base to firmly fix it to the shield well structure to prevent displacement during shield advancement.

[0034] Before the shield machine mainframe is hoisted into the well, hard lubricating oil is applied to the track of the starting base to reduce the resistance of the shield machine when it moves forward on the starting base.

[0035] After the construction site is ready, the shield equipment is transported to the site. The assembly of the shield machine main unit downhole includes the following steps: the shield base is installed, and then the middle shield, front shield, cutter head, assembler, and shield tail are hoisted down the well and installed on the shield base; in practice, a 300t crawler crane is used to hoist the middle shield, front shield, cutter head, assembler, and shield tail down the well, and the main and auxiliary hooks are used to turn over and drop each accessory onto the starting base, and then assemble and connect them. After the assembly is completed, professional technicians will conduct calibration and acceptance;

[0036] The installation of the reaction frame and reference ring includes the following steps:

[0037] First, hoist the lower beam of the reaction frame into the well for assembly, then hoist the side beam and the upper part of the reaction frame into the well and assemble them together with the lower beam;

[0038] Lift the lower half of the reference ring into the well and connect it to the lower crossbeam of the reaction frame. Then lift the upper half of the reference ring and connect it to the upper part of the reaction frame and the lower half of the reference ring respectively. Ensure that the center of the reference ring coincides with the center of the reaction frame and assemble the two.

[0039] Adjust the reaction frame in the horizontal and axial directions to make the center lines of the reaction frame and the reference ring consistent with the axis of the tunnel, and finally weld and fix the reaction frame;

[0040] When installing the reaction frame, a double-jointed H35 steel welding system is used to support the reaction frame and the main structure of the launch shaft;

[0041] Due to the semi-ring split start, the shield machine mainly uses the lower cylinder jack. For safety reasons, the lower support is encrypted to meet the starting thrust requirements;

[0042] Then seal the door:

[0043] The construction of the tunnel door seal is carried out in two steps:

[0044] Step 1: During the construction of the starting end wall, do a good job of burying the pre-buried steel ring of the starting tunnel door;

[0045] Step 2: Before the shield is officially started, install the extended steel ring and then install the sealing device consisting of the curtain rubber plate, folding plate, etc. as a temporary waterproof measure during the shield construction phase;

[0046] The temporary water stop of the opening is divided into two stages:

[0047] Phase 1: When the shield machine started to dig in parts, since the main machine (cutterhead + shield body) was 9.3m long and the tail of the shield had not yet entered the curtain, the waterproofing measures for the tunnel gate mainly relied on a temporary water-stopping device composed of a rubber curtain and a folding pressure plate.

[0048] The second stage: After the shield tail passes through the curtain 0.5m, the four grouting pipes of the shield tail are used to synchronously grout the gaps around the pipe segments in time. If there is still water leakage after synchronous grouting, secondary reinforcement grouting should be carried out. The secondary reinforcement grouting is carried out by an independent double-liquid grouting pump. The slurry is cement and water glass double slurry with a water-cement ratio of 1:1 and a cement slurry: water glass volume ratio of 1:1. When the water seepage is large, the initial setting time of the slurry is not more than 20s;

[0049] The specific requirements for connecting the rear supporting trolley to the shield machine are as follows:

[0050] A total of 6 rear supporting trolleys are arranged as a whole beside the working well, and the pipelines are neatly arranged. The layout method is: the hydraulic pipeline is placed on one side of the ground trolley, and the remaining pipelines of the shield are placed in the middle of the trolley. During the advancement of the shield, a special person is arranged to monitor the pipeline to avoid pipeline breakage. Specifically:

[0051] (1) The layout of the extended pipeline should follow the separation of fluid and hydraulic pipelines; avoid the hydraulic pipes from flattening the fluid pipelines;

[0052] (2) In the hydraulic pipeline, the return oil pipeline and the drain oil pipeline are tied separately to prevent the pipeline from being compressed and prevent the pipeline from being folded during dragging and dropping, resulting in excessive return oil pressure;

[0053] (3) Power cables, control cables and signal cables should be bundled separately to prevent interference and communication failure;

[0054] (4) Control lines and video lines should be dragged and dropped separately because they are thin and extended, and should not be dragged and dropped together;

[0055] (5) Pipelines that need to pass through the soil transportation channel on the ground must be buried underground with a depth of no less than 0.7 meters. After laying, 100 mm thick fine sand must be laid on top and then covered with steel plates for protection. The covering width should exceed 200 mm on both sides of the pipeline to avoid damage to the pipeline during soil transportation;

[0056] After the extended pipeline is lowered underground, it is accurately and firmly connected to the interfaces of the shield machine host. After the connection is completed, the equipment debugging begins:

[0057] (1) No-load debugging

[0058] Before the shield machine starts excavation, it is necessary to conduct a comprehensive system debugging to ensure that the shield machine is in good standby state. After the shield machine is assembled, it can be debugged without load. The purpose of the no-load debugging is mainly to check whether the equipment can operate normally; the main debugging contents are: whether the power distribution system, hydraulic system, lubrication system, cooling system, control system, grouting system are operating normally and calibrating various instruments; the debugging items are shown in Table 1 Shield machine debugging items Table 1:

[0059] Table 1 Shield machine commissioning project list

[0060] Serial number project content 1 Knife disc Forward and reverse rotation, speed 2 Screw Conveyor Rotation, speed 3 In and out gate Open, Close, Travel 4 Propulsion Jack Extension, contraction, working pressure 5 Segment assembly machine Forward and reverse, axial movement, lifting hand 6 Segment conveyor Axial movement, action 7 Human Gate Pressure test 8 Foam test spray All nozzles 9 Shield tail grease Trial injection 10 Slurry storage tank Rotating spiral blades 11 Grouting pump start up 12 Belt conveyor start up 13 Super digging knife Stretch and shrink 14 Cooling circulating water Open 15 Air Compressor start up 16 Grease pump start up

[0061] (2) Load debugging

[0062] After the no-load debugging confirms that the shield machine has working capacity, load debugging can be carried out; the main purpose of load debugging is to check the load capacity of various pipelines and seals; to make the various working systems and auxiliary systems of the shield machine reach the working state that meets the normal production requirements. Usually, the trial excavation time is the time for equipment load debugging. During load debugging, strict technical and management measures will be taken to ensure project safety, project quality and tunnel line shape.

[0063] After the debugging of the shield machine is completed, the main machine starts to push empty. During the empty push, the upper oil top is locked, and the lower oil cylinder is used to push forward empty. During the empty push, the negative ring is assembled. The negative ring is assembled with 16-point through seams, and only three large pieces are assembled to ensure that the width of the upper opening of the segment is greater than the width of the equipment bridge. The main machine empty push and negative ring assembly process are as follows:

[0064] The first step is to assemble the negative 8-ring segments, tighten the segment bolts, and then use the bottom push cylinder in the assembly mode to push out the three segments to contact the reaction frame to form a half-ring assembled negative 8 ring, and push the negative 8 ring to a suitable position to install the negative 7-ring segment;

[0065] The second step is to assemble the negative 7 ring according to the steps of assembling the negative 8 ring, tighten the longitudinal and circumferential segment bolts, use I-beams between the starting platform and the reaction frame as the bottom support of the segment, and set up triangular supports on both sides to prevent the segment from rolling and deflecting. Then push out the negative 7 ring, and the segment will be attached to the reaction frame. Continue to push the shield machine so that it slides along the starting frame to the position where the negative 6 ring segment can be assembled;

[0066] The third step is to advance the negative 6 ring. When advancing, observe the distance between the cutterhead and the tunnel face. When the cutterhead is close to the tunnel face, start to advance in the excavation mode to control the advancement speed. After the cutterhead is close to the tunnel face, start pressurized excavation. After excavation, install three segments to form the negative 6 ring. After the negative 6 ring is assembled, start to excavate the negative 5 ring and lay the track on the segments at the same time.

[0067] Step 4: When the minus 5 ring has excavated about 1500mm, start using the gantry crane to lift the segments in blocks. The segments are placed horizontally on the trolley on the track and manually dragged to the bottom of the segment installation machine. Note that the track blocker is installed on the front track to prevent the trolley from losing control and crashing into the equipment. After excavation is completed, use the segment installation machine to assemble the segments in half rings.

[0068] Step 5: Repeat the process of tunneling and installing the segments for the negative 5 rings, tunneling and installing the negative 4, negative 3, negative 2, and negative 1 rings for the half rings, and finally assembling the full ring for the 0 ring; Figure 3 This is a schematic diagram of the negative ring after installation;

[0069] Installation of axial support system: 609 steel pipe supports are used to effectively connect the upper part of the 0 ring with the reaction frame. A total of 4 609 steel pipe supports are arranged as the force transmission system between the upper half ring and the reaction frame. The 4 supports are arranged symmetrically along the axis of the negative ring, and a trolley downhole passage is left at the top. Anti-falling measures are set for the steel pipe supports, and steel plates are used to fill the gap between the steel pipe supports and the reaction frame to ensure that the load is effectively transmitted to the reaction frame during the start of the shield split;

[0070] After the negative ring is installed, the split start is: first a single host machine is used for excavation, then the excavation is transferred again, and finally the second excavation is carried out. After the split start is completed, the whole machine will excavate normally.

[0071] When the shield machine enters the hole for the first time, the specific requirements are as follows:

[0072] 1. When the main engine is excavating on the starting bracket, grease is applied on the rail surface. The thrust shall not be greater than 500t. At the same time, the starting bracket and reaction frame shall be monitored, and the sealing of the tunnel door shall be checked;

[0073] 2. After the main engine enters the hole, the cutter head speed should not be too high when cutting the soil. Increase the amount of foam, turn off the screw conveyor, stop mucking and gradually establish soil pressure balance. After the soil pressure is established, start excavating. The excavation volume per ring is 58.6m 3 about;

[0074] 3. The initial soil bin pressure is set to 0.85 bar, the excavation speed should not be too large, and should be controlled at 10 mm / min to 20 mm / min, the cutter head speed is controlled at 0.8 r / min-1.0 r / min, and the torque is controlled at 500 kN / m-800 kN / m;

[0075] 4. After 24 rings and 36 meters into the hole, the machine was stopped to prepare for the first transfer to the second stage of excavation;

[0076] After the main engine has advanced 36 meters, a transfer operation is carried out to remove the foam pipes and hydraulic pipes in the extended pipeline, and the hoisting equipment bridge and No. 1 trolley are installed in the tunnel to be assembled with the main engine. The segment crane of the equipment is used normally to lift the segments.

[0077] Step 1: Remove some of the extended pipelines in the first phase, including grease pipelines and foam pipelines, and move the foam system to the designed position of the equipment; after the water circulation system and industrial gas system pipelines are transferred, continue to extend forward;

[0078] Step 2: Remove temporary sleepers and install normal sleepers;

[0079] Step 2: Hoist the equipment bridge and No. 1 trolley, connect them to the main engine, and install the equipment bridge, No. 1 trolley, and the main engine to connect the pipelines normally;

[0080] Step 3: Make a temporary slag outlet bracket at the rear of No. 1 trolley and install the slag outlet;

[0081] Step 4: Install temporary belt conveyor;

[0082] Step 5: After the transfer, the main extension pipelines that need to be used are fluid pipelines and cables, which are the same as the excavation conditions in the first stage and will not be repeated;

[0083] After the transfer, the horizontal transportation adopts the formation of slag bucket + tractor head + mortar truck + segment truck, and the slag is discharged from the slag outlet at the rear of trailer No. 1;

[0084] After the first transfer and debugging is completed, continue to excavate to 85m (the total length of the shield machine is 85m);

[0085] After the first transfer, the shield tunneling reaches 85m, and the second transfer is carried out. All extended pipelines are removed, and the No. 2 to No. 6 trolleys are hoisted into the tunnel and assembled and connected with the No. 1 trolley, and then the normal excavation mode is switched. The specific steps include the following:

[0086] Step 1: Remove all extension pipelines connected to the main machine of the shield machine, hoist the extension pipelines to the ground, and properly stack and store them;

[0087] Step 2: Hoisting of trolleys No. 2 to No. 6. The hoisting of the trolleys is the same as the one-time transfer trolley hoisting conditions, so I will not repeat them here;

[0088] Step 3: After the lifting of trolleys No. 2 to No. 6 is completed, they are connected to the rear side of trolley No. 1 in sequence for debugging.

[0089] Step 4: The split start is completed and the whole machine resumes normal excavation.

[0090] Quality control measures: (1) When positioning the starting bracket, reaction frame and the first ring negative ring segment, the installation accuracy of the starting bracket, reaction frame and negative ring must be strictly controlled to ensure that the shield starting posture basically coincides with the designed line; (2) When positioning the first ring negative ring segment, the rear end face of the segment should be perpendicular to the center line of the line; (3) The axis of the negative ring segment coincides with the tangent of the line, and the negative ring segment adopts a staggered assembly method; (4) The segment must be inspected for quality upon arrival and stored properly; (5) The waterproof material of the segment must be inspected on site and can only be used after the waterproof adhesive quality of the segment is qualified; (6) Segment hoisting (7) Strictly control the shield tunneling parameters to ensure that the tunneling parameters are within the range of data simulation calculation results; (8) Strictly control the slag output and timely monitor and analyze the slag samples and slag soil temperature; (9) Strictly control the synchronous grouting volume and grouting pressure; (10) During the segment assembly process, strictly follow the process sequence; (11) Do a good job in controlling the secondary grouting volume to prevent the ground from sinking or uplifting; (12) Strictly control the mix ratio of synchronous grouting and secondary grouting, and do a good job in testing the grouting raw materials.

[0091] The advantages of the split start and half ring installation of the present invention are mainly reflected in the following aspects:

[0092] 1. Advantages of split origination

[0093] Split launch is mainly suitable for construction sites with narrow space, such as areas with dense underground pipelines in cities or environments with tight land resources. Its advantages include:

[0094] Space saving: By lifting and assembling the main shield machine and the supporting trolley separately, the space required underground can be significantly reduced, which is particularly suitable for construction environments with limited space.

[0095] Improved efficiency: Split launch allows for partial assembly of equipment in the launch well before subsequent assembly, which reduces the time and complexity of overall assembly.

[0096] Flexibility: Split launching can flexibly adjust the order of assembly and advancement according to different geological conditions and construction progress.

[0097] 2. Advantages of half-ring installation

[0098] The semi-ring installation is mainly used for the negative ring segments of shield machines. Its advantages include:

[0099] Strong adaptability: In space-constrained environments, half-ring segments can effectively reduce the required installation space while maintaining the continuity of shield advancement.

[0100] Good stability: The semi-ring structure can increase the stability of the negative ring segments through steel pipe support and reduce the deformation or damage of the segments during the advancement process.

[0101] Cost-effectiveness: Compared with full-ring segments, the use of half-ring segments can save materials and installation time, thereby reducing costs.

[0102] In summary, the split starting and semi-ring installation technologies are both innovative solutions for specific construction environments. They reduce construction costs and shorten construction periods by optimizing space utilization and equipment configuration, while also reducing the impact on the surrounding environment. They are one of the important technologies in modern shield construction.

[0103] The construction method disclosed in the present invention optimizes the design of the rear guide tunnel for the start of the wind shaft shield, cancels the construction of the rear guide tunnel, saves the relevant construction costs, and shortens the start-up period of the shield, saves a lot of construction costs, and achieves good economic benefits. The economic benefit analysis is shown in Table 2 below:

[0104] Table 2 Summary of economic benefit analysis using this method (double line)

[0105]

[0106] The comparison is as follows:

[0107] 1. According to the original design, the rear guide tunnel needs to be constructed for 54 meters, with a standard cost of 61,172 yuan per linear meter. The total cost of the double-line guide tunnel is: 54×2×61,172=6,606,576 yuan.

[0108] 2. After the original rear pilot tunnel was cancelled, the section was constructed using the shield method, with a cost of 37,000 yuan per linear meter. The total cost of the double lines is: 54×37,000×2=3,996,000 yuan;

[0109] 3. The conventional hoisting cost of a single shield machine is 539,338 yuan, and the total cost of two shield machines is 1,078,676 yuan;

[0110] 4. The installation cost of a split-type shield machine is RMB 1,350,000 per unit, and RMB 2,700,000 for two units in total;

[0111] 5. The construction period of the pilot tunnel method is 90 days, and the construction period of the split start is 65 days, which saves 25 days of construction period and saves a total of 14,000 × (90-65) = 350,000 yuan in management fees;

[0112] Total cost savings: 6,606,576-3,996,000+1,078,676-2,700,000+350,000=1,339,252 yuan.

[0113] In summary, the invention discloses a construction method for starting a shield machine. When the negative ring segments are installed between the reaction frame and the tunnel portal, only three segments on the lower side (i.e., three standard blocks from 3 o'clock to below 9 o'clock) are pushed out to form a semi-ring starting system to provide reaction force. When the negative ring is assembled by semi-rings, a horizontal steel support system is arranged at the upper part between the 0 ring and the reaction frame to ensure that the upper reverse thrust can be effectively transmitted to the reaction frame when the shield is started in split form, and provide forward thrust to the shield machine. When the semi-ring assembly is started, there is enough space on the upper part of the negative ring, so that the turnover materials for the starting of the shield can be quickly lowered into the well. In addition, the method is subsequently started in split form, i.e., a shield is used. The split start is carried out in the form of single-host excavation + secondary transfer of the main machine. During the split start, the space required underground can be significantly reduced by separately hoisting and assembling the shield main machine part and the rear supporting trolley. It is particularly suitable for construction environments with limited space. In addition, because the split start allows part of the equipment to be assembled in the starting shaft first, and then subsequent assembly is carried out, the time and complexity of the overall assembly can be reduced. During the split start, the slag transportation and turnover material hoisting can be vertically transported from the downhole channel on the upper side of the negative ring. In summary, the method for split starting of the shield machine disclosed in the present invention can effectively reduce costs, and at the same time effectively shorten the construction period, thereby improving the shield excavation efficiency.

[0114] When this method is used for the shield split start construction, the force transmission system is intuitive and clear. At the same time, because there is no pipe segment in the upper half ring, the space can be used flexibly and the operation is convenient at the start. At the same time, the size of the working shaft required for the shield start is greatly reduced, and there is no need to construct a pilot tunnel, which greatly reduces various impacts and interferences on social traffic and human living environment during construction, and achieves good social benefits.

[0115] The embodiments described above are only preferred specific implementation methods of the present invention, and the protection scope of the present invention is not limited thereto. Any simple changes or equivalent replacements of the technical solutions that can be obviously obtained by any technician familiar with the field within the technical scope disclosed in the present invention belong to the protection scope of the present invention.

Claims

1. A construction method initiated by a shield machine, characterized in that: The specific steps include: The shield machine mainframe is lowered into the well for assembly, and then the reaction frame and reference ring are installed; Install the negative ring. When installing the negative ring, the shield machine mainframe pushes out three segments from the 3 o'clock position to below the 9 o'clock position in the assembly mode. The three segments contact the lower part of the reaction frame to form a negative 8 ring of semi-ring assembly. Then continue to push out three segments to assemble on the rear side of the negative 8 ring to form a negative 7 ring of semi-ring assembly. Use the same method to assemble the negative 6 ring, negative 5 ring, negative 4 ring, negative 3 ring, negative 2 ring and negative 1 ring in sequence on the rear side of the negative 7 ring. When assembling the semi-ring, ensure that the width of the upper opening of the segment is greater than the width of the equipment bridge. Then assemble the 0 ring between the shield machine mainframe and the negative 1 ring and complete the installation of the negative ring. The shield machine mainframe made its first excavation; After hoisting the No. 1 trolley on the ground to the underground, it is connected to the shield machine host and a transfer excavation is carried out; The No. 2 to No. 6 trolleys on the ground were hoisted into the underground and connected with the No. 1 trolley in turn for secondary transfer excavation. After the secondary transfer excavation was completed, the whole machine excavated normally.

2. A shield machine-initiated construction method according to claim 1, characterized in that: After the negative ring is installed, steel supports are symmetrically arranged along the axis of the negative ring to form an axial support system. When installing the axial support system, the upper part of the negative 0 ring is connected to the upper part of the reaction frame.

3. A shield machine-initiated construction method according to claim 2, characterized in that: Four steel pipes are used when installing the axial support system. The four steel pipes are distributed on both sides in groups of two, and a downhole passage is left in the middle to allow the trolley to pass through.

4. A shield machine-initiated construction method according to claim 1, characterized in that: The assembly of the shield machine main unit downhole specifically includes the following steps: The shield base is installed, and then the middle shield, front shield, cutter head, assembler and tail shield are hoisted into the well and installed on the shield base.

5. A shield machine-initiated construction method according to claim 4, characterized in that: Install the reaction frame and reference ring, including the following steps: First, hoist the lower beam of the reaction frame into the well for assembly, then hoist the side beam and the upper part of the reaction frame into the well and assemble them together with the lower beam; Lift the lower half of the reference ring into the well and connect it to the lower crossbeam of the reaction frame. Then lift the upper half of the reference ring and connect it to the upper part of the reaction frame and the lower half of the reference ring respectively. Ensure that the center of the reference ring coincides with the center of the reaction frame and assemble the two. The reaction frame is adjusted in the horizontal and axial directions so that the center lines of the reaction frame and the reference ring are consistent with the axis of the tunnel, and finally the reaction frame is welded and fixed.

6. A shield machine-initiated construction method according to claim 5, characterized in that: When installing the reaction frame, a double-jointed H35 steel welding system is used to support the reaction frame and the main structure of the launch shaft.

7. A shield machine-initiated construction method according to claim 1, characterized in that: Lubricating oil is applied to the tunneling track surface when the shield machine main body is excavating for the first time.

8. A shield machine-initiated construction method according to claim 1, characterized in that: Before hoisting the No. 1 trolley for single-transfer excavation, the foam pipe and hydraulic pipe in the extension pipeline need to be removed, and then the equipment bridge and the No. 1 trolley can be hoisted to enter the tunnel. The excavation distance during single-transfer excavation is the total length of the shield machine main unit.

9. A shield machine-initiated construction method according to claim 8, characterized in that: During the first transfer excavation, a slag outlet is installed behind the No. 1 trolley, and a temporary belt conveyor is installed at the same time, and the slag is discharged from the slag outlet of the No. 1 trolley.

10. A shield machine-initiated construction method according to claim 1, characterized in that: After the first transfer excavation is completed, all extension pipelines are removed and hoisted to the ground, trolleys No. 2 to No. 6 are hoisted into the tunnel, and trolleys No. 2 to No. 6 are connected to the rear side of trolley No. 1 in sequence, and then the whole machine excavates normally.

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