Shield split launching construction method in narrow space

Abstract

The invention relates to a shield split launching construction method in a narrow space, which comprises the following steps of: assembling negative ring duct pieces and performing shield split launching, and performing construction in a partial or complete split tunneling mode; the construction process of the negative ring duct piece comprises the steps of construction preparation, negative ring duct piece hoisting, negative 8 ring duct piece point location positioning, duct piece splicing, jack stretching out, duct piece position adjusting, connecting bolt re-tightening and steel wire rope reinforcing. The construction period can be guaranteed, meanwhile, the attractiveness of the formed tunnel can be guaranteed, and compared with an underground excavation construction method, the construction period can be greatly shortened, and safety can be greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of shield machine starting in subway tunnels, in particular to a shield split starting construction method in a narrow space. Background Art

[0002] With the continuous development and utilization of urban underground space, tunnel engineering has become increasingly important.

[0003] The traditional underground excavation construction method is slightly insufficient in the construction of longer tunnels due to various factors, such as strict requirements on the construction period, rising labor costs, increased safety requirements, and higher expectations for the aesthetics and economy of the tunnel.

[0004] In order to overcome the shortcomings of traditional dark excavation construction methods, shield construction technology has been widely used in tunnel engineering. With its high efficiency, safety and automation, shield construction technology has significantly improved the efficiency and quality of tunnel construction.

[0005] The shield machine is a large-scale dark tunnel construction machinery that integrates multiple functions such as propulsion, excavation, and lining. It can continuously and efficiently complete tunnel excavation and support operations.

[0006] However, there are the following problems under special construction conditions: Limited site: However, under some special construction conditions, such as small site space, the traditional shield overall launch method is difficult to implement. This is because the shield machine is large and requires sufficient space for assembly and launch.

[0007] Insufficient launch shaft length: In addition, if the launch shaft length is insufficient, it will not meet the overall launch requirements of the shield machine, which will result in the shield machine being unable to smoothly enter the tunnel for excavation operations.

[0008] In summary, although shield construction technology has significant advantages in tunnel engineering, under certain special construction conditions, such as limited site and insufficient launch shaft length, the traditional shield overall launch method may be difficult to implement. This requires engineers to conduct sufficient on-site surveys and scheme designs before construction to ensure the smooth application of shield construction technology. At the same time, it is also necessary to continuously explore and innovate new construction methods and technical means to meet the needs of different construction conditions. Summary of the invention

[0009] The present invention aims to overcome the defects of the prior art, provide a shield split starting construction method in a narrow space, and solve the problem of normal shield tunneling construction in a narrow space.

[0010] In order to solve the above-mentioned technical problems, the present invention is achieved as follows: A shield split start construction method in a narrow space is characterized in that it includes the following steps: it includes the steps of negative ring segment assembly and shield split start, and the construction is carried out by partial or full separate excavation.

[0011] The method for split shield construction in a narrow space is characterized in that the construction process of the negative ring segment is: construction preparation → lifting of the negative ring segment → point positioning of the negative 8 ring segment → segment assembly → extending the jack → segment position adjustment → re-tightening of the connecting bolts → wire rope reinforcement.

[0012] The method for constructing a shield split start in a narrow space is characterized in that: the assembly of the negative ring segments includes: all negative rings are reinforced concrete segments, 8 negative rings are set on the left and right lines of the shield section, and before assembling the first ring of negative ring segments, 6 square steels with a length of 1.4m are longitudinally temporarily welded within a 180° range at the lower part of the shield tail segment assembly area as pads to ensure a reasonable gap between the inner side of the shield tail and the segments, and after the whole ring is assembled in the shield machine, the segments are slowly pushed out of the shield tail by using the shield machine propulsion jack. Since there is a gap of 100mm between the track surface of the start base and the outer side of the segments, in order to prevent the negative ring segments from sinking after being completely pushed out of the shield tail, round steels are spot welded or wooden wedges are added on the pre-buried steel plate of the start base to fill the gap between the start base track and the outer side of the segments so as to lift the negative ring concrete segments; As the negative ring segments are assembled, the segments will gradually lean towards the reaction frame. After the negative ring segments are fixed to the reference ring, the negative ring is further assembled and the shield machine quickly passes through the tunnel portal to start excavation and construction. After the second negative ring, the segments will be installed in the normal way.

[0013] The method for split shield construction in a narrow space is characterized in that the negative ring segments are assembled with staggered seams, the segment installation sequence is to first put the bottom segment in place, and then install it crosswise from bottom to top, the adjacent segments in each ring should control the ring surface flatness and sealing size, and finally insert the top segment to form a ring.

[0014] The method for starting construction of a shield split in a narrow space is characterized in that the installation steps of the negative ring segment are: a. Special personnel shall inspect the type, age, appearance quality, etc. of the segments. The segments can be unloaded only after they are qualified. The gantry crane will place the segments on the self-made segment transport vehicle, and then the segment crane will lift the segments to the assembly machine for assembly; b. Install the first ring of segments (minus 8) and push them back with a jack to connect them to the reference ring; c. Retract the jack and install the second ring of negative ring segments (negative 7); d. Shield advances the third ring (minus 6); e. The shield machine advances to the fourth ring (minus 5); f. After installing the negative 1 ring, the shield continues to move forward and install the 0 ring, which needs to be dismantled later.

[0015] The shield split start construction method in a narrow space is characterized in that the assembly method of the negative ring segment is: (1) Switch the excavation mode on the operating panel to the segment installation mode. At this time, the jack can be controlled by the control panel on the shield machine assembly platform; (2) Retract the jack in the installation area of ​​the first segment; (3) After the assembly machine clamps the pipe segment, it rotates and translates to send the first pipe segment to the installation position; (4) After aligning the first segment with the previous ring in the radial and circumferential directions, use the installer to move longitudinally and compress it into place; (5) Extend the jack, insert and tighten the longitudinal bolts; (6) Release the installer and prepare to lift the second segment; (7) Retract the jack in the installation area of ​​the second segment; (8) After the second segment is roughly aligned with the previous segment and the first segment, fine-tune and align the bolt holes; (9) Extend the jack, insert and tighten the longitudinal bolts and transverse bolts; (10) Install the third, fourth, and fifth segments in the same way; (11) The fourth and fifth segments are adjacent to the capping segment. To ensure the installation clearance of the capping segment, when installing the fifth segment, the distance between the front and rear ends of the two adjacent segments must be ensured, and the inner surfaces of the two adjacent segments must be kept on the same arc surface; (12) Apply lubricant evenly on the sides of two adjacent blocks and the sides of the capping block; (13) The capping block is first radially pressed into the installation position in the center. Generally, the excavation is stopped when the jack stroke is greater than 1800 mm. After adjustment, it is slowly inserted longitudinally. If there is any obstruction, it should be slowly pulled out and adjusted. (14) Extend the jack, insert and tighten the longitudinal and circumferential bolts; (15) Switch the segment installation mode on the operating panel to the excavation mode; during the excavation process, tighten the segments after they have come out of the shield tail again. Before the subsequent shield excavation reaches each ring of segment assembly, the connecting bolts of the three adjacent rings should be fully inspected and tightened again. When tightening the bolts, ensure that the tightening torque reaches 300 kN.m.

[0016] The method for starting construction of a shield machine in a narrow space is characterized in that the step of starting construction of a shield machine includes: (a) bracket laying; According to the simulation of the starting longitudinal section, the bottom plate of the shield starting shaft needs to be laid with a bracket with a length of 12300mm; (ii) Installation of reaction frame; According to the simulation of the starting longitudinal section, the reaction frame of the shield starting shaft is installed to the side wall of the starting shaft; (3) The first stage of shield tunneling starts in stages; Negative ring assembly: 1. -8~-4 ring installation: According to the simulation of the starting longitudinal section, 8 negative rings need to be installed in the starting well of the shield. In order to consider the lifting of slag from the wellhead in the second to third stages, 7.5m of space for lifting the 18m³ slag bucket in the later stage is reserved. The -8 to -4 rings need to be assembled in half rings. First, the shield machine moves forward to assemble -8 to -6 semi-rings, and then breaks the 1200mm concrete piles of the tunnel portal. After the breaking is completed, the cutterhead continues to move forward to assemble -5 to -4 semi-rings. After the -4 semi-rings are assembled, the cutterhead reaches the tunnel face. 2. Half ring reinforcement: After the -8~-4 rings are assembled, 4 steel supports are used for reinforcement; the reaction frame is connected with flange bolts, and the cylinder is reinforced with straight support; 3. Excavation of the first 3m (-3 to -2 ring): According to the simulation of the horizontal and vertical profiles of the shield machine and the starting shaft, after the shield machine starts to excavate, there is no condition for the shield machine to discharge slag forward, the effective distance between the tail of the screw machine and the reaction frame is 861mm, and the clearance for hoisting to the shaft is too small. It is necessary to carry out 2 rings of lateral discharge of slag, and sufficient space is reserved between the reaction frame and the tail of the screw machine for hoisting slag soil; The lateral slag discharge is within the half ring, and the placement and size of the slag bucket need to be simulated. According to the simulation of the shield machine size, a 1.5*1.5*1m slag bucket is used for slag discharge, and 20 I-beams are laid at the bottom as track support for the segment car. The -3~-2 rings are excavated and excavated, and the main power source for the segment car is the electric hoist; (iv) The second phase of the excavation began; (1) Dismantling of the lateral slag discharge device: -After the 2-ring assembly is completed, the lateral slag discharge device will be dismantled, the lateral track and sleepers will be removed, the normal battery car track will be restored, and the screw machine will be used for forward slag discharge. The estimated construction period will be changed by 1 day; (2) Second stage split starting size analysis: In order to improve the efficiency, it is necessary to replace the 18m³ soil bucket for excavation. Checking the shield machine drawings, the closest distance to the installation position of the belt slag main unit is at the tail of the No. 1 trolley. The slag discharge device needs to be 4m away from the tail of the No. 1 trolley. The size of the 18m³ slag bucket also needs to be considered. According to the size of the slag bucket and the trolley, after the tail of the No. 1 trolley enters the 0 ring, it can enter the third stage of split start. The tail of the No. 1 trolley needs to be 32m away from the 0 ring, and the shield needs to excavate and assemble to complete 18 rings; (3) (-1 to 18 rings) Excavation: -1 to 18 ring excavation is for forward slag discharge from the screw machine mouth. According to the height of the screw machine outlet and the maximum retracted size of the assembly machine, -1 to 18 ring excavation can only use a 4.85m³ small bucket of 2.5*1.3*1.5 meters for slag discharge; (V) Secondary initial modification and debugging: After the shield tunneling has completed 18 rings, the connecting bridge and No. 1 trolley can be connected, and the belt excavation port is modified to the tail of No. 1 trolley, and 18 cubic meters of soil boxes are used for excavation; (1) First, remove the connecting split starting pipeline connecting the bridge to the shield, and remove the connecting pipeline between the No. 1 trolley and the next five trolleys; (2) The connecting bridge and the first trolley are moved forward and assembled with the main engine. (3) Restore the original pipeline from Cart 1 to the main engine; (4) Carriage No. 1 is connected to the separate departure pipelines of the next five cars; (5) The excavation port was moved to the rear of the No. 1 trolley; (6) Belt vulcanization and debugging According to the above work content, the total construction period is planned to be 7 days; (VI) The third phase of the excavation is underway: 1. Analysis of the initial dimensions of the third stage; The excavation length of the third stage needs to be considered to improve efficiency. The required distance for full-group excavation is calculated based on the length of the shield machine. The total length of the shield machine is 84m. Considering the reserved effective soil lifting distance of 7.5m at the wellhead, the tail of the No. 6 trolley needs to be at the tail of the -3 ring to enable full-group excavation. The shield machine needs to be excavated and assembled after 50 rings are completed before the whole machine is assembled; 2. (Rings 19 to 50) Excavation; The slag outlet for the 19-50 rings is at the rear of the No. 1 trolley. The battery car marshaling adopts the form of 1 slurry car + 1 18m³ soil bucket + 1 segment car for excavation operation; the slurry car is placed in front of the soil box to ensure that both excavation and slurry extraction can be completed; 3. (19-50 rings) ergonomics analysis; Use 18m³ soil bucket to discharge slag, lift 4 buckets / ring, each bucket lifts soil for 10 minutes, excavate each ring for a total of 300 minutes, and the segment assembly time is 60 minutes. The rest of the time is the material preparation time. It is planned to be 4 rings / day, and the total construction period is 8 days; (VII) The fourth stage of excavation progress: 1. Assembly and commissioning of complete machines; After the shield machine excavated 50 rings, the tail of the shield machine No. 6 trolley was at the -3 ring position, which was enough for the battery car to be excavated in a whole train. The split start was completed, the split start pipeline was removed, the slag discharge device at the tail of the No. 1 trolley was removed and restored, and the trolley was marshaled and debugged as a whole. The estimated construction period is 7 days; 1. The fourth stage is the initial size analysis; After the shield machine splits and starts, it can meet the requirements of one train group for excavation. In order to improve work efficiency, it is necessary to install a turnout for two train groups to excavate. At present, the tail of the shield machine No. 6 trolley is at the -3 ring. The wellhead size and the dark excavation size are not enough to meet the turnout laying requirements. According to the analysis of the track change distance of the two train groups, it is necessary to use one train group to continue to excavate to the 100th ring. After the tail of the No. 6 trolley is at the 52 ring, the turnout can be laid. 2. (51-100 rings) single-row marshaling tunneling; A whole train of battery cars is used to discharge the slag, with 4 buckets / ring. Each bucket takes 10 minutes to move the soil. The excavation plan is 5 rings / day, with a total construction period of 10 days. (8) Turnout and slope change installation, double-row marshaling configuration; After the shield machine has completed 100 rings of excavation and assembly, excavation will be stopped. A turnout will be laid 15m inside the 0th ring of the tunnel. 15m from the turnout, a variable slope steel sleeper will be installed from the turnout to the tail of the trolley to the tail of the normal electric car, and a double row of tracks will be laid in front of the turnout into the dark excavated tunnel. During the laying period, the negative ring will be removed. The planned construction period is 10 days.

[0017] The beneficial effects of the present invention are as follows: It can be seen from the above technical scheme that the present application provides a shield split start construction method in a narrow space, and adopts a split start construction method for tunnel shield excavation construction. This construction method is slow relative to the overall shield excavation speed, but relative to the tunnel dark excavation construction method, it can greatly save construction period and labor costs. The overall start of the shield is suitable for all strata except hard rock, and the construction is continuous, saving labor and other construction costs. At the same time, it can ensure the construction period, safety and aesthetics. For shield construction in a narrow space, the overall start space is insufficient, and the shield equipment cannot be fully installed. However, in order to ensure the advantages of construction period and aesthetics, the shield split start construction method is gradually used in engineering. The use of this construction scheme can not only ensure the construction period, but also ensure the aesthetics of the formed tunnel. Compared with the dark excavation construction method, it can also greatly save the construction period and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the positioning of the negative ring segment; Figure 2 It is the bracket layout diagram; Figure 3 It is the layout diagram of the reaction frame; Figure 4 Diagram for assembling -8 to -6 ring and semi-ring and removing concrete piles.

[0019] Figure 5 This is a schematic diagram for assembling -5 to -4 ring and half rings.

[0020] Figure 6 Schematic diagram of half ring reinforcement.

[0021] Figure 7 This is a schematic diagram of the advancement of rings -3 to -2.

[0022] Figure 8 This is a schematic diagram of lateral slag discharge.

[0023] Fig. 9 This is a schematic diagram of slag discharge after 18 rings.

[0024] Fig.10 This is a schematic diagram of slag discharge from -1 to 18 rings.

[0025] Fig.11 This is a schematic diagram of slag discharge from rings 19 to 50.

[0026] Fig.12 This is a schematic diagram of slag discharge after 50 rings. DETAILED DESCRIPTION

[0027] The technical solutions of the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field without creative work based on the embodiments in the embodiments of the present application are within the scope of protection requested by the present application. A shield split start construction method in a narrow space, the operation steps are as follows: 1. Negative ring segment assembly All negative rings are made of reinforced concrete segments. Eight negative rings are set on the left and right lines of the shield section. The outer diameter of the segments is 6.2m, the inner diameter is 5.5m, and the length of each ring is 1.5m. It consists of 6 segments, including the capping block (K), adjacent block (B1), adjacent block (B2), standard block (A1), (A2), and (A3). M27 oblique bolts are used for longitudinal and circumferential connection. Each ring is equipped with 12 bolts in the longitudinal direction and 16 bolts in the circumferential direction.

[0028] Before assembling the first ring of negative ring segments, 6 square steels with a length of 1.4m are temporarily welded longitudinally within the 180° range below the shield tail segment assembly area as pads to ensure a reasonable gap between the inner side of the shield tail and the segments. Figure 1After the whole ring is assembled in the shield machine, the shield machine propulsion jack is used to slowly push the segment out of the shield tail. Since there is a 100mm gap between the track surface of the starting base and the outer side of the segment, in order to prevent the negative ring segment from sinking after being pushed out of the shield tail, round steel is spot welded or wooden wedges are added to the embedded steel plate of the starting base to fill the gap between the starting base track and the outer side of the segment so as to lift the negative ring concrete segment.

[0029] As the negative ring segments are assembled, the segments will gradually move toward the reaction frame. After the negative ring segments are fixed to the reference ring, the negative rings are further assembled, and the shield machine quickly passes through the tunnel door to start excavation. After the second negative ring, the segments will be installed in the normal way.

[0030] 1). Negative ring segment assembly The negative ring segments are assembled with staggered seams. The installation sequence of the segments is to put the bottom segment in place first, and then install them crosswise from bottom to top. The flatness of the ring surface and the sealing size of the adjacent segments in each ring should be controlled, and finally the top segment is inserted to form a ring.

[0031] 2). Construction process Construction preparation → hoisting of negative ring segments → positioning of negative 8 ring segments → segment assembly → extending jacks → segment position adjustment → re-tightening of connecting bolts → wire rope reinforcement.

[0032] 3). Construction method ① Construction preparation (1) Adjust the shield machine based on the measurement to ensure that the center position is consistent with the designed center position of the tunnel.

[0033] (2) Prepare reinforcement materials and tools such as sandbags, water pumps, water pipes, square timber, steel sections, wire ropes, and jacks.

[0034] (3) Prepare communication tools inside and outside the cave and lighting equipment inside the cave.

[0035] (4) After the pipe segments have passed the quality inspection at the prefabrication plant, they are transported to the construction site by a special flatbed transport vehicle for temporary storage. Wooden blocks should be placed between the upper and lower pipe segments.

[0036] (5) Before installing the segments, prepare the segments and connecting parts, clean up the debris at the shield tail, and check that the lifting arm and other equipment of the segment assembly machine are operating normally before installing the segments.

[0037] ②Installation steps (1) A dedicated person will inspect the segment type, age, appearance quality, etc. The segment can be unloaded only after passing the inspection. The 45 / 16t gantry crane will place the segment on the self-made segment transport vehicle, and then the segment crane will lift the segment to the assembly machine for assembly.

[0038] (2) Install the first ring of segments (minus 8) and push them back with a jack to connect them to the reference ring.

[0039] (3) Retract the jack and install the second ring of negative segments (negative 7).

[0040] (4) The shield advances the third ring (minus 6).

[0041] (5) The shield machine advances to the fourth ring (minus 5).

[0042] (6) After installing the negative 1 ring, the shield continues to move forward to install the 0 ring, which needs to be removed later.

[0043] ③Assembly method (1) Switch the excavation mode on the operating panel to the segment installation mode. At this time, the jack can be controlled by the control panel on the shield machine assembly platform.

[0044] (2) Retract the jack in the installation area of ​​the first segment.

[0045] (3) After the assembly machine clamps the pipe segment, it rotates and translates to send the first pipe segment to the installation position.

[0046] (4) After aligning the first segment with the previous ring in the radial and circumferential directions, use the installer to move it longitudinally and compress it into place.

[0047] (5) Extend the jack, insert and tighten the longitudinal bolts.

[0048] (6) Release the installer and prepare to lift the second segment.

[0049] (7) Retract the jack in the installation area of ​​the second segment.

[0050] (8) After the second segment is roughly aligned with the previous segment and the first segment, fine-tune the alignment of the bolt holes.

[0051] (9) Extend the jack, insert and tighten the longitudinal bolts and transverse bolts.

[0052] (10) Install the third, fourth, and fifth segments in the same way.

[0053] (11) The fourth and fifth segments are adjacent to the capping block. To ensure the installation clearance of the capping block, when installing the fifth segment, it is important to ensure the distance between the front and rear ends of the two adjacent segments and keep the inner surfaces of the two adjacent segments on the same arc surface.

[0054] (12) Apply lubricant evenly on the sides of the two adjacent blocks and the two sides of the capping block.

[0055] (13) The capping block is first radially pressed into the installation position in the center. Generally, the excavation is stopped when the jack stroke is greater than 1800 mm. After adjustment, it is slowly inserted longitudinally. If there is any obstruction, it should be slowly pulled out and adjusted.

[0056] (14) Extend the jack, insert and tighten the longitudinal and circumferential bolts.

[0057] (15) Switch the segment installation mode on the operating panel to the excavation mode. During the excavation process, tighten the segments after they have come out of the shield tail again. Before the subsequent shield excavation reaches each ring of segments, the connecting bolts of the adjacent three rings should be fully inspected and tightened again. When tightening the bolts, ensure that the tightening torque reaches 300KN.m.

[0058] ④Quality control measures (1) The negative ring segments are installed one by one in the shield machine, and are pushed out by the shield machine's propulsion jack until they rest against the reference ring. The outer side of the segment that has escaped from the shield shell is reinforced with steel wire and the lower end is tightened with wooden wedges to ensure that the segment does not float or shift during the thrust transmission process. At the same time, the thrust of the jack is evenly transmitted to the reaction frame.

[0059] (2) The guide rails of the starting base must be straight, and the elevation, spacing and center axis must be strictly controlled.

[0060] (3) Apply butter on the base rails before starting to reduce the thrust resistance of the shield.

[0061] (4) Before the shield machine fully enters the tunnel portal, an anti-twist device should be welded on the shell and removed gradually as the shield machine advances.

[0062] (5) Allowable error in segment assembly: During construction, the direct ovality of the segment lining ring shall not exceed 5‰D (D is the outer diameter of the tunnel), the radial misalignment of adjacent segments shall be ≤5mm, and the annular misalignment of adjacent segments shall be ≤6mm.

[0063] (6) Negative ring segments are temporary segments and need to be removed later. They do not need sealing strips and bolts do not need water-stop washers.

[0064] (7) Use wooden or steel plugs to seal the bottom of the segment and the rail to prevent the segment from sinking.

[0065] (8) During the segment assembly operation, the jacks must be extended and retracted correctly, and the oil pressure and the number of jacks extended must be strictly controlled to ensure that the shield does not retreat during assembly. When the segments are assembled into a ring, the connecting bolts should be initially tightened piece by piece, and then tightened again after the shield tail is removed. Before the subsequent shield excavation reaches each ring of segment assembly, the connecting bolts within the adjacent 3 rings should be fully inspected and tightened again. When tightening the bolts, ensure that the bolt tightening torque reaches 300KN.m.

[0066] (9) Before installing the segments, the garbage at the bottom of the shield should be cleaned to prevent impurities from being mixed between the segments.

[0067] (10) Special machines and tools are required to ensure smooth transportation and flipping of the segments.

[0068] (11) When stacking pipe segments on the ground, wooden blocks should be placed between the upper and lower pipe segments.

[0069] (12) The accurate position of the reference ring must be ensured; the ring surface must be flat and perpendicular to the tunnel design axis. If errors are found, wedges must be made as soon as possible to correct the ring surface.

[0070] (13) Strengthen training and business learning, equip on-site operators with testing equipment, arrange personnel on site to give unified command, and ensure the consistent assembly of pipe segments. Strengthen training and business learning, equip on-site operators with testing equipment, arrange personnel on site to give unified command, and ensure the consistent assembly of pipe segments.

[0071] 2. Shield tunneling starts (a) Bracket laying, such as Figure 2 As shown: According to the simulation of the starting longitudinal section, a 12,300 mm long bracket needs to be laid on the bottom plate of the shield starting shaft.

[0072] (ii) Installation of reaction frame, such as Figure 3 As shown: According to the simulation of the starting longitudinal section, the reaction frame of the shield starting shaft is installed from top to the side wall of the starting shaft.

[0073] (III) The first stage of shield tunneling started Negative ring assembly 1. -8 to -4 ring installation According to the simulation of the starting longitudinal section, 8 negative rings need to be installed in the shield starting shaft. In order to consider the lifting of slag from the wellhead in the second to third stages, 7.5m of space for lifting the 18m³ slag bucket in the later stage is reserved, and -8 to -4 rings need to be assembled in half rings.

[0074] like Figure 4 , 5 As shown: First, the shield machine moves forward to assemble -8 to -6 rings and half rings, and then breaks the 1200mm concrete piles of the tunnel. After the breaking is completed, the cutter head continues to move forward to assemble -5 to -4 rings and half rings. After the -4 ring and half ring are assembled, the cutter head reaches the face.

[0075] 2. Half ring reinforcement After the -8~-4 rings are assembled, 4 steel supports are used for reinforcement. The reaction frame is connected with flange bolts, and the oil cylinder is reinforced with straight support. The reinforcement diagram is as follows Figure 6 shown.

[0076] 3. Excavation of the first 3m (-3 to -2 ring) like Figure 7 , 8 As shown, according to the simulation of the horizontal and vertical sections of the shield machine and the starting shaft, after the shield machine starts to excavate, there is no condition for the shield machine to discharge slag forward, the effective distance between the tail of the screw machine and the reaction frame is 861mm, and the clearance for hoisting to the well is too small, so lateral discharge of slag is required for 2 rings, and sufficient space is reserved between the reaction frame and the tail of the screw machine for hoisting slag; For lateral slag discharge within a half ring, it is necessary to simulate the position and size of the slag bucket. According to the simulation of the shield machine size, a 1.5*1.5*1m slag bucket is used for slag discharge. 20 I-beams are laid at the bottom as track support for the segment car. Excavation is carried out from -3 to -2 rings, and the main power source for the segment car is the electric hoist.

[0077] (IV) Second phase of excavation 1. Removal of the lateral slag discharge device -After the 2-ring assembly is completed, the lateral slag discharge device will be dismantled, the lateral track and sleepers will be dismantled, the normal battery car track will be restored, and the screw machine will be used for forward slag discharge. The construction period is expected to be changed by 1 day.

[0078] (II) Second stage split starting size analysis like Fig. 9 As shown, in order to improve efficiency, the 18m³ soil bucket needs to be replaced for excavation. Looking at the shield machine drawings, the closest distance to the installation position of the belt slag discharge main unit is at the tail of trolley No. 1, and the slag discharge device needs to be 4m away from the tail of trolley No. 1. The size of the 18m³ slag bucket also needs to be considered. According to the size of the slag bucket and the trolley, after the tail of trolley No. 1 enters the 0 ring, it can enter the third stage of split start. The tail of trolley No. 1 needs to be 32m away to enter the 0 ring, and the shield needs to excavate and assemble to complete 18 rings.

[0079] (III) (-1 to 18 rings) Excavation -1 to 18 ring excavation is for the forward discharge of the screw machine mouth. According to the height of the screw machine mouth and the maximum retracted size of the assembly machine, -1 to 18 ring excavation can only use a 4.85m³ small bucket of 2.5*1.3*1.5 meters to discharge the slag, such as Fig.10 shown.

[0080] (V) Secondary initial modification and debugging After the shield tunneling completed 18 rings, the connecting bridge and No. 1 trolley can be connected, and the belt excavation port is relocated to the tail of No. 1 trolley. 18 cubic meters of soil box is used for excavation.

[0081] (1) First, remove the connecting split starting pipeline connecting the bridge to the shield, and remove the connecting pipeline between the No. 1 trolley and the next five trolleys; (2) The connecting bridge and the first trolley are moved forward and assembled with the main engine. (3) Restore the original pipeline from Cart 1 to the main engine; (4) Carriage No. 1 is connected to the separate departure pipelines of the next five cars; (5) The excavation port was moved to the rear of the No. 1 trolley; (6) Belt vulcanization and debugging Based on the above work content, the total construction period is planned to be 7 days.

[0082] (VI) The third phase of the excavation began 1. Analysis of the starting size of the third stage The excavation length of the third stage needs to be considered to improve efficiency. The distance required for full-group excavation is calculated based on the length of the shield machine. The total length of the shield machine is 84m. Considering the reserved 7.5m effective soil lifting distance at the wellhead, the tail of the No. 6 trolley needs to be at the tail of the -3 ring to enable full-group excavation. The shield needs to excavate and assemble 50 rings before the whole machine can be assembled.

[0083] 2. (Ring 19 to 50) Excavation The slag outlet for 19-50 rings is at the rear of the No. 1 trolley. The battery car marshaling adopts the form of 1 slurry car + 1 18m³ soil bucket + 1 segment car for excavation operation. The slurry car is placed in front of the soil box to ensure that both excavation and slurry extraction can be completed. Fig.11 shown.

[0084] 3. (Ring 19-50) Ergonomics Analysis An 18m³ soil bucket is used to discharge the slag, and 4 buckets are hoisted per ring. The soil transportation time for each bucket is 10 minutes. The total excavation time for each ring is 300 minutes. The time for assembling the segments down to the well is 60 minutes. The rest of the time is the preparation time for materials down to the well. It is planned to be 4 rings / day, and the total construction period is 8 days.

[0085] (VII) The fourth stage of excavation 1. Assembly and debugging of the whole machine like Fig.12 As shown: After the shield machine excavated 50 rings, the tail of the shield machine No. 6 trolley was at the -3 ring position, which was enough for the battery car to be excavated in a whole train, the split start was completed, the split start pipeline was removed, the slag discharge device at the tail of the No. 1 trolley was removed and restored, and the trolley was assembled and debugged as a whole. The estimated construction period is 7 days.

[0086] 1. Fourth stage starting size analysis After the shield machine split start is completed, it can meet the needs of one train group for excavation. In order to improve work efficiency, it is necessary to install switches for two train groups to excavate. Now the tail of shield machine No. 6 trolley is at -3 ring. The wellhead size and concealed excavation size are not enough to meet the requirements for turnout laying. According to the analysis of the track change distance of the two train groups, it is necessary to use one train group to continue excavating to the 100th ring. The tail of No. 6 trolley is at the 52 ring before the turnout laying can be carried out.

[0087] 2. (51-100 rings) single-row tunneling A whole train of battery cars is used to unload slag, with 4 buckets per ring. The soil transportation time for each bucket is 10 minutes. The excavation plan is 5 rings per day, with a total construction period of 10 days.

[0088] (VIII) Turnout and slope change installation, double-row marshaling configuration After the shield machine excavates and assembles 100 rings, it stops excavating and lays a turnout 15m inside the 0th ring of the tunnel. At 15m from the turnout, a variable slope steel sleeper is installed from the turnout to the tail of the trolley to the tail of the normal battery car. Double-row tracks are laid in front of the turnout into the dark tunnel. During the laying period, the negative ring is removed. The planned construction period is 10 days. The above is only the embodiment provided by this application and is not intended to limit this application. Although this application is described in detail with reference to the embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents. However, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application should be included in the protection scope of this application.

Claims

1. A shield split start construction method in a narrow space, characterized in that It includes the following steps: It includes the steps of assembling negative ring segments and starting the shield separately, and is constructed by partial or complete separate excavation.

2. The method for starting construction of a shield machine in a narrow space according to claim 1, characterized in that: The construction process of the negative ring segment is: construction preparation → lifting of the negative ring segment → positioning of the negative 8 ring segment → segment assembly → extending the jack → segment position adjustment → re-tightening of the connecting bolts → wire rope reinforcement.

3. The method for starting construction of a shield machine in a narrow space according to claim 2, characterized in that: The negative ring segment assembly includes: all negative rings are reinforced concrete segments, 8 negative rings are set on the left and right lines of the shield section, before assembling the first negative ring segment, 6 square steels with a length of 1.4m are temporarily welded longitudinally within a 180° range at the lower part of the shield tail segment assembly area as pads to ensure a reasonable gap between the inner side of the shield tail and the segment, and after the whole ring is assembled in the shield machine, the segment is slowly pushed out of the shield tail by using the shield machine propulsion jack. Since there is a 100mm gap between the starting base track surface and the outer side of the segment, in order to prevent the negative ring segment from sinking after being completely pushed out of the shield tail, round steel is spot welded or wooden wedges are added on the pre-buried steel plate of the starting base to fill the gap between the starting base track and the outer side of the segment so as to lift the negative ring concrete segment; As the negative ring segments are assembled, the segments will gradually lean towards the reaction frame. After the negative ring segments are fixed to the reference ring, the negative ring is further assembled and the shield machine quickly passes through the tunnel portal to start excavation and construction. After the second negative ring, the segments will be installed in the normal way.

4. The method for starting construction of a shield machine in a narrow space according to claim 3, characterized in that: The negative ring segments are assembled with staggered seams. The installation sequence of the segments is to put the bottom segment in place first, and then install them crosswise from bottom to top. The flatness of the ring surface and the sealing size of the adjacent segments in each ring should be controlled, and finally the top segment is inserted to form a ring.

5. The method for starting construction of a shield machine in a narrow space according to claim 2, characterized in that: The installation steps of the negative ring segment are: a. Special personnel shall inspect the type, age, appearance quality, etc. of the segments. The segments can be unloaded only after they are qualified. The gantry crane will place the segments on the self-made segment transport vehicle, and then the segment crane will lift the segments to the assembly machine for assembly; b. Install the first ring of segments (minus 8) and push them back with a jack to connect them to the reference ring; c. Retract the jack and install the second ring of negative ring segments (negative 7); d. Shield advances the third ring (minus 6); e. The shield machine advances to the fourth ring (minus 5); f. After installing the negative 1 ring, the shield continues to move forward and install the 0 ring, which needs to be dismantled later.

6. The method for starting construction of a shield machine in a narrow space according to claim 2, characterized in that: The assembly method of the negative ring segment is: (1) Switch the excavation mode on the operating panel to the segment installation mode. At this time, the jack can be controlled by the control panel on the shield machine assembly platform; (2) Retract the jack in the installation area of ​​the first segment; (3) After the assembly machine clamps the pipe segment, it rotates and translates to send the first pipe segment to the installation position; (4) After aligning the first segment with the previous ring in the radial and circumferential directions, use the installer to move longitudinally and compress it into place; (5) Extend the jack, insert and tighten the longitudinal bolts; (6) Release the installer and prepare to lift the second segment; (7) Retract the jack in the installation area of ​​the second segment; (8) After the second segment is roughly aligned with the previous segment and the first segment, fine-tune and align the bolt holes; (9) Extend the jack, insert and tighten the longitudinal bolts and transverse bolts; (10) Install the third, fourth, and fifth segments in the same way; (11) The fourth and fifth segments are adjacent to the capping segment. To ensure the installation clearance of the capping segment, when installing the fifth segment, the distance between the front and rear ends of the two adjacent segments must be ensured, and the inner surfaces of the two adjacent segments must be kept on the same arc surface; (12) Apply lubricant evenly on the sides of two adjacent blocks and the sides of the capping block; (13) The capping block is first radially pressed into the installation position in the center. Generally, the excavation is stopped when the jack stroke is greater than 1800 mm. After adjustment, it is slowly inserted longitudinally. If there is any obstruction, it should be slowly pulled out and adjusted. (14) Extend the jack, insert and tighten the longitudinal and circumferential bolts; (15) Switch the segment installation mode on the operating panel to the excavation mode; during the excavation process, tighten the segments after they have come out of the shield tail again. Before the subsequent shield excavation reaches each ring of segment assembly, the connecting bolts of the three adjacent rings should be fully inspected and tightened again. When tightening the bolts, ensure that the tightening torque reaches 300 kN.m.

7. The method for starting construction of a shield machine in a narrow space according to claim 1, characterized in that: The steps for starting the shield split include: (a) bracket laying; According to the simulation of the starting longitudinal section, the bottom plate of the shield starting shaft needs to be laid with a bracket with a length of 12300mm; (ii) Installation of reaction frame; According to the simulation of the starting longitudinal section, the reaction frame of the shield starting shaft is installed to the side wall of the starting shaft; (3) The first stage of shield tunneling starts in stages; Negative ring assembly:

1. -8~-4 ring installation: According to the simulation of the starting longitudinal section, 8 negative rings need to be installed in the starting well of the shield. In order to consider the lifting of slag from the wellhead in the second to third stages, 7.5m of space for lifting the 18m³ slag bucket in the later stage is reserved. The -8 to -4 rings need to be assembled in half rings. First, the shield machine moves forward to assemble -8 to -6 semi-rings, and then breaks the 1200mm concrete piles of the tunnel portal. After the breaking is completed, the cutterhead continues to move forward to assemble -5 to -4 semi-rings. After the -4 semi-rings are assembled, the cutterhead reaches the tunnel face.

2. Half ring reinforcement: After the -8~-4 rings are assembled, 4 steel supports are used for reinforcement; the reaction frame is connected with flange bolts, and the cylinder is reinforced with straight support; 3. Excavation of the first 3m (-3 to -2 ring): According to the simulation of the horizontal and vertical profiles of the shield machine and the starting shaft, after the shield machine starts to excavate, there is no condition for the shield machine to discharge slag forward, the effective distance between the tail of the screw machine and the reaction frame is 861mm, and the clearance for hoisting to the shaft is too small. It is necessary to carry out 2 rings of lateral discharge of slag, and sufficient space is reserved between the reaction frame and the tail of the screw machine for hoisting slag soil; The lateral slag discharge is within the half ring, and the placement and size of the slag bucket need to be simulated. According to the simulation of the shield machine size, a 1.5*1.5*1m slag bucket is used for slag discharge, and 20 I-beams are laid at the bottom as track support for the segment car. The -3~-2 rings are excavated and excavated, and the main power source for the segment car is the electric hoist; (iv) The second phase of the excavation began; (1) Dismantling of the lateral slag discharge device: -After the 2-ring assembly is completed, the lateral slag discharge device will be dismantled, the lateral track and sleepers will be removed, the normal battery car track will be restored, and the screw machine will be used for forward slag discharge. The estimated construction period will be changed by 1 day; (2) Second stage split starting size analysis: In order to improve the efficiency, it is necessary to replace the 18m³ soil bucket for excavation. Checking the shield machine drawings, the closest distance to the installation position of the belt slag main unit is at the tail of the No. 1 trolley. The slag discharge device needs to be 4m away from the tail of the No. 1 trolley. The size of the 18m³ slag bucket also needs to be considered. According to the size of the slag bucket and the trolley, after the tail of the No. 1 trolley enters the 0 ring, it can enter the third stage of split start. The tail of the No. 1 trolley needs to be 32m away from the 0 ring, and the shield needs to excavate and assemble to complete 18 rings; (3) (-1 to 18 rings) Excavation: -1 to 18 ring excavation is for forward slag discharge from the screw machine mouth. According to the height of the screw machine outlet and the maximum retracted size of the assembly machine, -1 to 18 ring excavation can only use a 4.85m³ small bucket of 2.5*1.3*1.5 meters for slag discharge; (V) Secondary initial modification and debugging: After the shield tunneling has completed 18 rings, the connecting bridge and No. 1 trolley can be connected, and the belt excavation port is modified to the tail of No. 1 trolley, and 18 cubic meters of soil boxes are used for excavation; (1) First, remove the connecting split starting pipeline connecting the bridge to the shield, and remove the connecting pipeline between the No. 1 trolley and the next five trolleys; (2) The connecting bridge and the first trolley are moved forward and assembled with the main engine. (3) Restore the original pipeline from Cart 1 to the main engine; (4) Carriage No. 1 is connected to the separate departure pipelines of the next five cars; (5) The excavation port was moved to the rear of the No. 1 trolley; (6) Belt vulcanization and debugging According to the above work content, the total construction period is planned to be 7 days; (VI) The third phase of the excavation is underway: 1) Analysis of the starting size of the third stage; The excavation length of the third stage needs to be considered to improve efficiency. The required distance for full-group excavation is calculated based on the length of the shield machine. The total length of the shield machine is 84m. Considering the reserved effective soil lifting distance of 7.5m at the wellhead, the tail of the No. 6 trolley needs to be at the tail of the -3 ring to enable full-group excavation. The shield machine needs to be excavated and assembled after 50 rings are completed before the whole machine is assembled; 2) (Ring 19-50) Excavation; The slag outlet for the 19-50 rings is at the rear of the No. 1 trolley. The battery car marshaling adopts the form of 1 slurry car + 1 18m³ soil bucket + 1 segment car for excavation operation; the slurry car is placed in front of the soil box to ensure that both excavation and slurry extraction can be completed; 3) (19-50 rings) ergonomic analysis; Use 18m³ soil bucket to discharge slag, lift 4 buckets / ring, each bucket lifts soil for 10 minutes, excavate each ring for a total of 300 minutes, and the segment assembly time is 60 minutes. The rest of the time is the material preparation time. It is planned to be 4 rings / day, and the total construction period is 8 days; (VII) The fourth stage of excavation progress:

1. Assembly and commissioning of complete machines; After the shield machine excavated 50 rings, the tail of the shield machine No. 6 trolley was at the -3 ring position, which was enough for the battery car to be excavated in a whole train. The split start was completed, the split start pipeline was removed, the slag discharge device at the tail of the No. 1 trolley was removed and restored, and the trolley was marshaled and debugged as a whole. The estimated construction period is 7 days; 1) Phase IV initial size analysis; After the shield machine splits and starts, it can meet the requirements of one train group for excavation. In order to improve work efficiency, it is necessary to install a turnout for two train groups to excavate. At present, the tail of the shield machine No. 6 trolley is at the -3 ring. The wellhead size and the dark excavation size are not enough to meet the turnout laying requirements. According to the analysis of the track change distance of the two train groups, it is necessary to use one train group to continue to excavate to the 100th ring. After the tail of the No. 6 trolley is at the 52 ring, the turnout can be laid. 2) (51 to 100 rings) single-row tunneling; A whole train of battery cars is used to discharge the slag, with 4 buckets / ring. Each bucket takes 10 minutes to move the soil. The excavation plan is 5 rings / day, with a total construction period of 10 days. (VIII) Installation of turnouts and slope changers, double-row marshaling configuration; after the shield machine has completed 100 rings of excavation and assembly, excavation will be stopped, and turnouts will be laid 15m inside the 0th ring of the tunnel. At 15m from the turnout, slope change steel sleepers will be installed from the turnout to the tail of the trolley to the tail of the normal battery car, and double-row tracks will be laid in front of the turnout into the dark tunnel. During the laying period, the negative ring will be removed. The planned construction period is 10 days.

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