Construction method for super-small-clearance shield overlapping tunnel starting and arriving

Abstract

The present application relates to the technical field of track construction equipment, and more particularly to a super-small clear distance shield overlapping tunnel starting and arriving construction method. The steps are as follows: S1: after the lower tunnel is completed, the radial uniform grouting is carried out by using the multi-hole type of the segment for the overlapping starting or arriving section; S2: the tunnel entrance is sealed again. The super-small clear distance shield overlapping tunnel starting and arriving construction method provided by the present application reduces the sand gushing, water gushing and grouting leakage risk of the shield machine starting or arriving by adopting the tunnel entrance sealing technology again, and has the advantages of simple structure, saving of a large amount of indirect construction cost, saving of a large amount of labor force under the premise of ensuring construction safety, and the effective use of the portal type steel support frame, which not only meets the high bearing capacity requirement of the upper tunnel starting or arriving shield machine, but also does not hinder the horizontal transportation of the lower tunnel electric car and the synchronous production of the rail top air duct.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of track construction equipment, in particular to a super-small-clearance shield overlapping tunnel starting and arriving construction method. BACKGROUND

[0002] With the rapid development of city modernization, overlapping tunnels are reused in major cities around the world, but are mostly constructed by open-cut method or mine method. In recent years, with the vigorous promotion of domestic urban rail transit construction and the popularization of shield tunneling method, tunnels designed in overlapping line form and constructed by shield method are increasing, especially in large cities where a large number of subway lines are constructed in old urban areas to alleviate the increasingly severe traffic pressure. Due to the influence of urban planning and existing buildings and structures space and the demolition work, such designs are constantly emerging and becoming a trend of normal design and construction.

[0003] At present, there are many successful cases of shield overlapping tunnel construction, which fully verify that the construction process of first constructing the lower tunnel and then constructing the upper tunnel is the best. However, based on the construction process of first lower tunnel and then upper tunnel, a series of technical problems still exist in the starting and arriving construction process of super-small-clearance shield overlapping tunnel, such as: ① the second disturbance of the upper tunnel to the stratum is large, how to control the soil erosion and reduce the stratum deformation of the overlapping starting or arriving end is a difficult problem; ② the tunneling speed is slow, which leads to the huge concentrated load of the upper tunnel shield machine tunneling of the super-small-clearance (1.36m) overlapping tunnel to the lower tunnel forming tunnel, how to ensure the strength and stability of the lower tunnel forming tunnel is a difficult problem; ③ the main part of the shield machine weighs about 350t, how to ensure the strength and stability of the support platform used by the upper tunnel shield machine starting or arriving is a difficult problem.

[0004] Therefore, we design a super-small-clearance shield overlapping tunnel starting and arriving construction method to provide another technical solution to the above technical problems. SUMMARY

[0005] Therefore, it is necessary to provide a super-small-clearance shield overlapping tunnel starting and arriving construction method to solve the technical problems raised in the background art.

[0006] In order to solve the above technical problems, the present application adopts the following technical scheme:

[0007] A super-small-clearance shield overlapping tunnel starting and arriving construction method, the steps are as follows:

[0008] S1: After the lower tunnel is completed, the radial uniform grouting is carried out by using the multi-hole type of segment for the overlapping starting or arriving section;

[0009] S2: The tunnel portal is sealed again;

[0010] S3: the tunneling process of the lower hole shield machine and the upper hole shield machine in the overlapping section, the synchronous grouting system of the shield machine is improved;

[0011] S4: for the 1.36m super-small clear distance overlapping tunnel, the synchronous extension 150*150 type steel stay is installed between the support gaps of the rubber wheels of the hydraulic wheel type synchronous support trolley;

[0012] S5: using a door type steel support frame to support the reinforced concrete middle plate structure;

[0013] S6: constructing a shield machine receiving platform.

[0014] As a preferred embodiment of the super-small clear distance shield overlapping tunnel starting and arriving construction method provided by the application, the secondary sealing of the hole is as follows:

[0015] Two 5mm arc-shaped steel plates form a complete closed arc-shaped ring;

[0016] The triangular plate is welded inside the hole steel ring, and the sponge is filled densely at the gap of the closed arc-shaped ring;

[0017] The sponge is fixed firmly on the outside by iron wire to prevent falling out, thereby forming a complete sealing belt behind the canvas rubber, achieving the purpose of secondary sealing.

[0018] As a preferred embodiment of the super-small clear distance shield overlapping tunnel starting and arriving construction method provided by the application, the secondary sealing of the hole further comprises a guide rail made of channel steel to guide the tunneling direction of the shield machine.

[0019] As a preferred embodiment of the super-small clear distance shield overlapping tunnel starting and arriving construction method provided by the application, the improvement of the synchronous grouting system of the shield machine is as follows:

[0020] After a tee joint is connected behind the original flow meter, the original synchronous grouting pipeline is kept normal;

[0021] A ball valve and a pressure sensor are sequentially connected to the added pipeline, and the pipeline is extended outward to the sixth trolley;

[0022] A grouting joint is reserved at A and B respectively on the first trolley and the sixth trolley;

[0023] The grouting joint at A is mainly responsible for the following grouting of the shield tail; the grouting joint at B is combined with the daily monitoring settlement report to supplement the mortar at the position with large cumulative settlement or large settlement rate.

[0024] As a preferred implementation form of the super-small clear distance shield overlapping tunnel originating and arriving construction method, the improvement of the synchronous grouting system of the shield machine further comprises connecting a water pipe into the pipeline, for C, and the pipeline can be quickly cleaned after each grouting to be ready for next use.

[0025] As a preferred implementation form of the super-small clear distance shield overlapping tunnel originating and arriving construction method, the construction shield machine receiving platform has the following steps:

[0026] 1) Clean the foundation and adjust the foundation elevation, and install the column;

[0027] 2) As a horizontal direction fixed support, use a scissor type channel steel to strengthen the fixation to achieve structural stability, sequentially weld from bottom to top, weld all the scissors between the two columns first, and then turn to other columns;

[0028] 3) Slowly lift the main beam by using the lifting crane through the main beam center lifting point, adjust the installation of the main beam and the column when lifting to the column directly above;

[0029] 4) Place the flat cross support on the measurement line, and fix by welding;

[0030] 5) Measure the elevation of the whole platform, after determining the overall flatness of the main beam and the cross beam, the 2mm panel is integrally lowered and welded, then the receiving frame is positioned again by measuring and laying the line, and then the receiving bracket is lowered and installed, and the left and right, front and rear supports are fixed;

[0031] 6) Measure the accurate positioning of each measuring point, and install the deflection meter and the strain meter.

[0032] As a preferred implementation form of the super-small clear distance shield overlapping tunnel originating and arriving construction method, the column installation comprises: foundation laying, lifting, correction, fixation;

[0033] ①Laying: lay the longitudinal and transverse reference lines of the foundation plane as the column bottom plate installation positioning line before installation;

[0034] ②Lifting: draw a horizontal line at 500-1000mm above the column bottom plate before lifting the column;

[0035] ③Correction: adjust the column bottom and the foundation line to the determined position when the column bottom is 40-100mm away from the foundation position;

[0036] ④Fixation: weld a 12.6 channel steel to reinforce the column at 1m away from the foundation bottom and 3.2m away from the top of the column between the columns.

[0037] As a preferred embodiment of the super-small-clearance shield overlapping tunnel starting and arriving construction method provided by the application, after the main beam is installed, two arc-shaped reinforcing steel plates with a length of 200mm and a width of 150mm are respectively welded at the contact positions of the main beam and the two sides of the column to prevent the left and right displacement of the main beam.

[0038] It can be seen without doubt that the above technical solutions of the application can certainly solve the technical problems to be solved by the application.

[0039] Meanwhile, by the above technical solutions, the application at least has the following beneficial effects:

[0040] The super-small-clearance shield overlapping tunnel starting and arriving construction method provided by the application reduces the risks of sand gushing, water gushing and slurry leakage of the shield machine starting or arriving by adopting the hole opening secondary sealing technology, and has a simple structure, saving a large amount of indirect construction cost; meanwhile, the following type secondary grouting is adopted to save a large amount of labor force under the premise of ensuring construction safety, and the effective use of the portal type steel support frame not only meets the high bearing capacity requirement of the shield machine starting or arriving at the upper hole, but also does not hinder the horizontal transportation of the electric car at the lower hole and the synchronous production of the track top air duct, greatly saving the cost of the traditional full-frame scaffold support, improving the efficiency and accelerating the construction progress.

[0041] The uniformity of the radial grouting of the overlapping tunnel is realized by using the 3-hole segment, the compactness of the starting or arriving end head soil is enhanced, the tunneling parameters of the shield machine starting or arriving at the upper hole are easy to control, and the safety risks of the shield machine starting or arriving at the upper hole are greatly reduced; the support is realized by using the hydraulic wheel type trolley, which is safer and more reliable than the traditional cross support scheme, and the operation is simple and convenient, greatly saving the construction period, and the 150*150 type steel stay is installed to be synchronously extended, enhancing the overall stability of the segment and increasing the safety factor of the super-small-clearance overlapping tunnel shield machine construction.

[0042] The steel structure platform successfully completes the receiving of the shield machine with a weight of about 350T, and realizes the smooth receiving of the overlapping tunnel shield machine at the upper hole under the special working condition of no middle plate structure. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0044] Figure 1 The super-small-clearance shield overlapping tunnel starting construction process flowchart of the application;

[0045] Figure 2 The arrival construction process flow chart of the super-small-clearance shield overlapping tunnel of the application;

[0046] Figure 3 The original hole sealing effect diagram of the application;

[0047] Figure 4 The secondary sealing structure schematic diagram of the application;

[0048] Figure 5 The grouting equipment modification schematic diagram of the application;

[0049] Figure 6 The special segment design schematic diagram of the application;

[0050] Figure 7 The radial grouting section schematic diagram of the application;

[0051] Figure 8 The steel flower pipe manufacturing schematic diagram of the application;

[0052] Figure 9 The hydraulic wheel type support trolley schematic diagram of the application;

[0053] Figure 10 The section steel bracing installation position schematic diagram of the application;

[0054] Figure 11 The door type section steel support frame structure arrangement schematic diagram of the application;

[0055] Figure 12 The steel platform structure arrangement schematic diagram of the application;

[0056] Figure 13 The shield machine receiving platform site effect diagram of the application. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical scheme and advantages of the application clearer and more understandable, the application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the application and do not limit the application.

[0058] In order to make the person in the art better understand the application scheme, the technical scheme in the embodiment of the application will be described clearly and completely below in combination with the drawings.

[0059] It should be noted that the embodiments in the application and the features and technical schemes in the embodiments can be combined with each other without conflict.

[0060] It should be noted that similar reference numbers and letters refer to similar items in the following drawings, and thus, once an item is defined in one drawing, it need not be further defined and explained in subsequent drawings.

[0061] Referring to Figures 1-13 A super-small-clearance shield overlapping tunnel starting and arriving construction method has the following steps:

[0062] S1: After the lower tunnel is completed, the radial uniform grouting is performed on the overlapping starting or arriving section by using the multi-hole type of the segment, which enhances the compactness of the soil at the starting or arriving end, and ensures the safe and stable starting or arriving of the upper tunnel shield machine;

[0063] S2: The secondary sealing technology at the tunnel portal is adopted, which effectively prevents the sand and water gushing and grout leakage of the shield machine during the starting or arriving stage, and well controls the water and soil loss of the end stratum;

[0064] The shield machine starting or arriving portal sealing device generally adopts rubber plates, which are composed of cord rubber, fan-shaped pressing plate, anti-turning plate, gasket and bolt. Before the installation of the portal sealing, the integrity, hardness and aging degree of the cord rubber are checked, the circular bolt hole position of the ring plate is checked, and the bolt hole of the cord rubber is processed in advance. Then, the bolt hole of the portal pre-logic piece is cleaned, and finally, the cord rubber plate, ring plate, fan-shaped pressing plate and anti-turning plate are installed in sequence, as shown in Figure 3 .

[0065] However, the posture of the shield machine is not easy to control during the starting or arriving construction, and the hinge plate in the portal range is often biased, which easily causes the water and sand gushing and grout leakage at the under-pressured part of the hinge plate. Therefore, two 5mm arc-shaped steel plates are used to form a complete closed arc-shaped ring, and the two arc-shaped steel plates are welded in the portal steel ring through the triangular plate. At the same time, the gap of the closed arc-shaped ring is filled with sponge, and the sponge is fixed firmly on the outside through the iron wire to prevent it from falling out, thereby forming a complete sealing belt behind the cord rubber (as shown in Figure 4 ), achieving the purpose of secondary sealing. A channel steel is used as a guide rail to guide the tunneling direction of the shield machine.

[0066] S3: During the tunneling process of the lower tunnel shield machine and the upper tunnel shield machine in the overlapping section, the convenient and rapid following type secondary grouting is realized by improving the synchronous grouting system of the shield machine, which improves the work efficiency of the secondary grouting on the basis of saving labor, and effectively alleviates the first and second deformation of the stratum in the starting or arriving section;

[0067] The shield machine of the first tunnel is used as the test section, and the tunneling parameters of the second tunnel are optimized based on the summary of the tunneling parameters of the first tunnel, so as to reduce the secondary disturbance.

[0068] 1. Tunneling control of the lower tunnel shield machine and the upper tunnel shield machine

[0069] (1) Key control of main tunneling parameters of the first lower tunnel

[0070] During normal tunneling, the optimal tunneling parameters are determined in time by combining the feedback of ground settlement monitoring, including earth pressure, speed, thrust, torque, synchronous grouting, articulation, earth volume, and improvement of spoil, etc. In particular, in the overlapping section, the tunneling parameters during tunneling are carefully recorded, and the optimal tunneling parameters of the corresponding position of the upper tunnel are determined in time based on the stratum characteristics. At the same time, balanced tunneling is adopted during tunneling, and balanced thrust, speed, and torque are used for tunneling to avoid the abnormality of one or two parameters, and the principle of continuous, balanced, full, and uniform speed is grasped for related control.

[0071] (2) Key control of main tunneling parameters of the second upper tunnel

[0072] When the net distance of the overlapping tunnel is less than 1.36 m, in order to reduce the disturbance of the shield machine construction to the surrounding soil and reduce the influence on the lower formed tunnel, based on the summary of the tunneling parameters of the corresponding position of the lower tunnel, the following points need to be paid special attention to:

[0073] ① Control principle of the vertical direction (elevation) of the shield machine: reasonably control the stroke difference of the thrust jacks, avoid large-scale axis correction actions, and grasp the principle of "frequent correction and less correction". During the thrust process, the DTA of the shield machine is lifted by 3 cm as a whole, and the vertical trend is always kept above +3 to prevent the "load head" or even the whole shield machine from sinking, and at the same time, the construction measurement results are continuously compared and checked with the calculated three-dimensional coordinates, and the deviation is adjusted in time.

[0074] ② The cutter head speed should not be too fast, and it is appropriate to control it at 1-1.3 r / min, and the penetration of the shield machine can be appropriately increased.

[0075] ③ Before assembling each ring of segments, it is necessary to manually review the shield tail gap of one ring of shield tail (measure 8-12 positions) to ensure the accurate selection of segments and prevent the posture of the shield machine from being difficult to control due to the small local shield tail gap, and even cause segment misalignment and damage to squeeze the tail shield.

[0076] After each ring of tunneling is completed, the last 5 rings of shield tail are followed by secondary grouting during the time of assembling the segments, which can quickly fill the loose area of the surrounding stratum, and at the same time, there is no need for manual grouting, which greatly saves labor.

[0077] Device modification and method of use as Figure 5 shown: by connecting a tee after the original flow meter, keeping the original synchronous grouting pipeline normal, connecting a ball valve and a pressure sensor on the added pipeline in turn, then extending the pipeline to the sixth trolley, and reserving a grouting joint at the first trolley and the sixth trolley respectively, namely the two places A and B in the figure, the grouting joint at A is mainly responsible for following grouting after the fifth ring of the shield tail; the grouting joint at B is used to supplement mortar at the position with large cumulative settlement or large settlement rate according to the daily monitoring settlement report. At the same time, a water pipe is connected to the pipeline, as shown at C in the figure, which can quickly clean the pipeline after each grouting to prepare for the next use. In order to facilitate operation, the control mode of the newly connected electrical equipment is written into the shield machine PLC program, so that the operator can complete all operations in the cab, and at the same time realize real-time monitoring of the grouting amount and grouting pressure of the secondary grouting.

[0078] 2. Radial uniform grouting construction of overlapping section

[0079] (1) Special segment prefabrication

[0080] Firstly, the overlapping section segment is specially designed into a 3-hole segment to increase the radial grouting hole position and facilitate uniform grouting around the segment. The design drawing of the special segment is shown in Figure 6 .

[0081] (2) Radial grouting reinforcement range

[0082] When the lower tunnel is completed or reaches the tunneling, radial uniform grouting reinforcement can be implemented to the upper tunnel tunneling range using the grouting holes on the upper half of the segment. The purpose is to strengthen the reinforcement interlayer and the local soil strength of the upper tunnel body.

[0083] The reinforcement depth is generally 2-3m, and radial grouting is implemented by using 5 continuous grouting holes vertically upward in combination with the actual hole position of the segment to improve the compactness and strength of the stratum in the reinforcement range. The specific grouting section is shown in Figure 7 .

[0084] (3) Radial grouting pipe setting

[0085] In order to ensure smooth construction, the radial grouting pipe is made of a seamless steel pipe with a diameter of φ32mm (steel pipe wall thickness of 6mm, and steel pipe with a waffle pattern of Φ10mm, spacing 200mm small holes) which is the same diameter as the reserved grouting hole (i.e. assembly screw hole), the length of the steel waffle pipe is determined according to the clear distance of the overlapping tunnel, the top end of the steel waffle pipe closest to the vertical direction is 20cm away from the tunnel arch bottom, and the length of the remaining 4 grouting pipes is set with this as a reference. An inverted valve needs to be installed on the grouting port during grouting to prevent underground water from flowing into the tunnel through the grouting pipe, and it also needs to be made into a form with a drill bit, as shown inFigure 8 as shown.

[0086] (4) Radial grouting material and grouting parameter selection

[0087] The grout uses cement-water glass double grout, cement is 42.5 grade ordinary portland cement, and the reinforcement range is every ring, and the unconfined compressive strength of the reinforced soil body is required to be not less than 0.4 Mpa. The grouting end standard is double control standard of grouting amount and pressure, and grouting can be ended at a position when the grouting amount of each hole is greater than 1.8 m3 or the grouting pressure reaches 1 Mpa. At the same time, a check valve needs to be installed on the grouting port during grouting to prevent underground water from flowing into the tunnel through the grouting pipe. The grout proportioning is shown in Table 1 below.

[0088] Table 1 Double liquid grout proportioning table

[0089]

[0090] (5) Drilling and grouting

[0091] First, a simple operation platform is erected in the lower tunnel, and the opening work of the grouting hole is completed by using the percussion drill, then the steel flower pipe with a drill bit is slowly jacked to the set position by using the soil nailing machine, and then the double liquid grout is injected by using a ZTGZ-120 / 150 electric grouting pump and the matching pipeline (which can be loaded by an electric car).

[0092] S4: For the overlapping tunnel with a super-small clear distance of 1.36 m, a 150*150 type steel stay that can be synchronously extended is installed between the support gaps of the rubber wheels of the hydraulic wheel type synchronous support trolley, so as to enhance the overall stability of the segment on the basis of meeting the strength;

[0093] In order to ensure the structural stability of the formed tunnel in the lower tunnel, the tunnel in the lower tunnel needs to be supported during the tunneling process of the shield machine in the upper tunnel. In order to realize continuous and uninterrupted support, a hydraulic wheel type trolley is adopted for support. The support trolley is composed of 4 sections, each section is 5 meters long, the net distance between sections is 1.5 meters, and the total length of the trolley is 22.5 meters. The support protection range is the range of 5 rings behind the position of the upper tunnel shield machine to 10 rings in front of the position of the upper tunnel shield machine. The trolley moves with the overall jacking movement of the upper tunnel shield machine, and the solid rubber wheel must be closely attached to the segment during the movement process to ensure that the trolley does not lose force. At the same time, segmented jacking movement measures are designed, and the trolley model is shown in Figure 9 as shown.

[0094] Meanwhile, for the 1.36m super-small clear spacing overlapping tunnel, on the basis of installing the support trolley, 4 rows of 150*150 steel bars which can be continuously extended are installed in the gaps between the 5 solid rubber wheels, and each steel bar is fixed firmly by means of two specially-made assembling heads of the segment hoisting holes, so as to enhance the overall stability of the lower hole forming segment. One steel bar is 4.5m long, 5 steel bars are arranged in one row, and the total length of the steel bars is 22.5m. The installation position of the steel bars is shown in Figure 10 .

[0095] S5: the portal steel support frame is used to support the reinforced concrete middle plate structure, that is, the high bearing capacity requirement of the upper hole starting or reaching the shield machine is met, the horizontal transportation of the lower hole electric vehicle and the synchronous production of the rail top air duct are not hindered, the operation is simple, and the portal steel support frame is easy to disassemble;

[0096] In order to meet the support requirements of the starting or reaching shield machine, the portal steel support frame can be installed below the middle plate structure before pouring the middle plate structure, so that high-strength support is realized, the horizontal transportation of the lower hole electric vehicle and the synchronous production of the rail top air duct are not hindered, the operation is simple, and the portal steel support frame is easy to disassemble.

[0097] The connection between the portal steel frames is all welded, and the weld height is 8mm.

[0098] ①Stand

[0099] There are 20 stands, each of which is made of a single 300*300 steel bar. A steel plate with a thickness of 1cm is welded to the upper and lower ends of each stand, and the size of the steel plate is 40cm*40cm. The lower end of the steel plate is connected to the bottom plate through 4 M20 expansion bolts, and the stands are connected into a whole through horizontal longitudinal rods and scissors braces of a steel pipe with a diameter of 48mm.

[0100] ②Longitudinal beam

[0101] The longitudinal beam is laid on the stand steel plate and is made of a single 300*300 steel bar. There are 4 longitudinal beams in total.

[0102] ③Cross beam

[0103] The distance between the cross beams is 80cm, and there are 15 cross beams in total. The cross beams are connected by 10 connecting rods made of Q235 steel. The above steel bars are arranged in 5 rows under the web plate of the cross beam, and there are 2 steel bars in each row with a spacing of 1m. There are 10 connecting rods in total. The overlapping parts of the cross beam and the longitudinal beam should be welded and fixed.

[0104] ④Formwork and square timber

[0105] The formwork is made of 18mm thick plywood, and the square timber with a size of 10cm*10cm is laid on the portal steel support frame. The laying distance of the square timber is 20cm.

[0106] The above materials are all Q235, and the structure arrangement of the portal steel support frame is shown in Figure 11 .

[0107] S6: through a shield machine receiving platform developed by independent research and development, solved the technical problems of large height on-hole shield machine receiving without middle plate structure, and ensured the safety and quality of construction, the benefit effect is obvious.

[0108] (1) the overall strength of the receiving platform

[0109] The total load of the steel platform: shield machine cutter + front body + middle body + rear body + screw machine + receiving frame and panel weight = 56t + 95t + 130t + 32t + 18t + 16t = 347t (according to the parameters of Herick S437 shield machine).

[0110] According to the steel platform design drawing, the self weight load of the shield machine is transmitted to the three main beams of the steel platform through the receiving frame, and the main beam is welded with the steel pipe support flat plate. The load of the shield machine acts on the receiving frame through the contact support point. The calculation considers that the load acting on the main beam is calculated as uniform line load. The middle main beam bears 1 / 2 load, and the two side main beams each bear 1 / 4 load. The middle main beam is selected as a steel frame for calculation and analysis. The length of the entire shield body plus cutter is 9.3 meters, so: F = 3470 KN / 9.3 m * 0.5 = 187 KN / m.

[0111] (2) receiving platform structure arrangement

[0112] ① Column: steel pipe Ф600x10mm, 12 pieces, welded at both ends on 20mm thick steel plate, then supported at the lower end on the station floor;

[0113] ② Main beam: I56a H-beam, 3 pieces;

[0114] ③ Secondary beam: I18a H-beam double splicing, 7 pieces;

[0115] ④ Panel: 20mm steel plate;

[0116] ⑤ Anchoring: M16 high-strength expansion bolts are used, 4 bolts are used for each column, a total of 48 bolts.

[0117] ⑥ Lateral fixation: longitudinal beam I56a and transverse double splicing I18a H-beam are respectively supported at both ends of the ring frame beam side to prevent lateral displacement of the steel platform.

[0118] The above materials are Q235, and the steel platform structure arrangement is shown in Figure 12 .

[0119] (3) receiving platform site construction

[0120] The specific process flow is as follows: column installation → scissors support welding → main beam installation → secondary beam installation → panel welding → receiving frame installation → construction monitoring.

[0121] 1) Column installation

[0122] The column installation is first to clean up the foundation and adjust the foundation elevation, and then install. Column installation main level includes: foundation layout, hoisting, correction, fixed.

[0123] ① Layout: install the longitudinal and transverse reference lines of the foundation plane as the column bottom plate installation positioning line before installation.

[0124] ② Hoisting: before lifting the column, draw a horizontal line at 500-1000mm above the column bottom plate, so as to make a review of the plane elevation reference before installation and fixation. According to the height of the column, determine the binding point on the upper part of the column with a rope, as the adjustment direction of the control rope, after the preparation work is ready, first try to hoist, stop hoisting when the height of one end is 100-200mm, check the fastness of the rigging and the stability of the crane, when the column bottom is located directly above the installation foundation, the crane can be commanded to slowly descend.

[0125] At the same time, due to the long line of the crane, on the basis of grasping the stable descent, each visual point reports the relevant situation in time during the descent process, and the hidden trouble is found and eliminated in time.

[0126] ③ Correction: when the column bottom is 40-100mm away from the foundation position, adjust the column bottom and the foundation reference line to the determined position, command the crane to descend and fix in place, and tighten all the bolts, temporarily pull up the cable wind rope to reinforce the column to achieve safety before removing the lifting hook, and the remaining 11 columns are hoisted in sequence according to this method.

[0127] ④ Fixation: weld a 12.6 channel steel between the columns and the column 1m away from the bottom of the foundation and 3.2m away from the top of the column to reinforce the column to achieve sufficient stability.

[0128] 2) Welding of scissors support

[0129] As a horizontal fixed support, the angle seam welding is controlled within 8mm, and the scissors type channel steel is used to strengthen the fixation to achieve structural stability. The welding process is carried out from bottom to top in turn, first weld all the scissors supports between the two columns, and then turn to other columns. The welding process should be fine and pay attention to safety, workers should wear safety belts, and in addition to the welder, two other people are responsible for on-site coordination and safety.

[0130] 3) Main beam installation

[0131] ① Take the main beam center lifting point and use the crane to slowly lift the main beam, adjust the installation reference line of the main beam and the column when hoisted directly above the column, and command the crane to descend and fix in place.

[0132] After the main beam is installed, two arc-shaped reinforcing steel plates with a length of 200 mm and a width of 150 mm are welded at the contact positions of the main beam and the two sides of the column to prevent the left and right displacement of the main beam. The corner seam welding is controlled within 8 mm to make it firm and stable enough. The high-altitude welding operation should pay attention to safety under the premise of making the welding effect reach the designed strength and stability.

[0133] The two ends of the main beam should be completely in contact with the ring frame beam and be ensured not to be affected by eccentric force. This is mainly to prevent the longitudinal displacement of the column.

[0134] 4) Installation of cross brace

[0135] According to the design requirements, the cross brace is placed flat on the measuring line and welded firmly. The end of the cross brace is welded with an I-beam to make it in contact with the ring frame beam and not affected by eccentric force. This is mainly to prevent the transverse displacement of the column.

[0136] 5) Installation of faceplate and receiving bracket

[0137] First, measure the elevation of the entire platform to confirm the overall flatness of the main beam and cross beam. Then, the 2mm faceplate is hoisted and welded as a whole. Then, the receiving bracket is positioned by measuring and laying out the line, and then the receiving bracket is installed and the left and right, front and rear supports are fixed.

[0138] 6) Precise positioning of each measuring point and installation and positioning of deflection meter and strain meter.

[0139] The steel structure receiving platform of the shield machine made on site is shown in Figure 13 .

[0140] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details and do not limit the application to the specific embodiments described. Obviously, many modifications and changes can be made according to the content of the specification. The embodiments are selected and described in detail in order to better explain the principles and practical applications of the application, so that those skilled in the art can well understand and utilize the application. The application is limited by the claims and their entire scope and equivalents.

Claims

1. A construction method for launching and receiving an overlapping tunnel with an ultra-small clear distance by a shield tunneling machine, characterized in that, The steps are as follows: S1: After the completion of the excavation of the lower hole tunnel, the radial uniform grouting is carried out by using the porous type of the segment for the overlapping originating or arriving section; S2: The hole is sealed for the second time; S3: The shield machine is improved during the excavation process of the overlapping section; S4: For the overlapping tunnel with a small net distance of 1.36m, the synchronous extension of 150*150 type steel stay is installed between the support gaps of the hydraulic wheel type synchronous support trolley; S5: The door type steel support frame is used to support the reinforced concrete middle plate structure; S6: The shield machine receiving platform is constructed; The steps of the second sealing of the hole are as follows: Two 5mm arc-shaped steel plates form a complete closed arc-shaped ring; The triangular plate is welded inside the hole door steel ring, and the sponge is filled in the gap of the closed arc-shaped ring; The outside of the sponge is fixed firmly by the iron wire to prevent falling out, and then a complete sealing band is formed behind the canvas rubber to achieve the purpose of secondary sealing; The steps of the improvement of the synchronous grouting system of the shield machine are as follows: After connecting a three-way to the rear of the original flow meter, the original synchronous grouting pipeline is kept normal; A ball valve and a pressure sensor are connected in sequence on the added pipeline, and the pipeline is extended outward to the sixth trolley; A grouting joint is reserved on the first trolley and the sixth trolley, namely A and B; The grouting joint at A is mainly responsible for the following grouting of the shield tail; the grouting joint at B is used to supplement the mortar at the position with large cumulative settlement or large settlement rate according to the daily monitoring settlement report; The improvement of the synchronous grouting system of the shield machine also includes connecting a water pipe to the pipeline for C, and cleaning the pipeline quickly after each grouting to prepare for the next use; The steps of the construction of the shield machine receiving platform are as follows: 1) Clean the foundation and adjust the foundation elevation, and then install the column; 2) As a horizontal fixed support, use scissors type channel steel to strengthen the fixation to achieve structural stability, and weld from bottom to top, first weld all the scissors braces between the two columns, and then turn to other columns; 3) Use the crane to slowly lift the main beam from the center lifting point of the main beam, adjust the installation alignment of the main beam and the column when the main beam is lifted above the column; 4) Place the horizontal support on the measurement alignment, and then fix it by welding; 5) Measure the elevation of the whole platform, and then weld the 2mm panel after determining the overall flatness of the main beam and the horizontal beam, and then measure and position the receiving frame again, and then install the receiving frame and fix the left and right, front and back supports; 6) Measure the accurate positioning of each measuring point, and install the deflection meter and strain meter; The column installation includes: foundation alignment, lifting, correction, and fixation; ①Alignment: Install the longitudinal and transverse reference lines of the foundation plane as the column bottom plate installation positioning line before installation; ②Lifting: Draw a horizontal line from the column bottom plate upward 500-1000mm before lifting the column; ③Correction: Adjust the column bottom and the foundation alignment to the determined position when the column bottom is 40-100mm away from the foundation position; ④ Fix: in the column and column between the bottom of the foundation 1 m, 3.2 m from the top of the column welded a 12.6 channel steel to reinforce the column.

2. The construction method of an overlapped tunnel with ultra-small clear distance according to claim 1, characterized in that, The secondary sealing of the hole also includes a guide rail made of channel steel to guide the direction of the shield tunneling.

3. The construction method of an overlapped tunnel with ultra-small clear distance according to claim 1, characterized in that, After the main beam is installed, two arc-shaped reinforcing steel plates with a length of 200 mm and a width of 150 mm are welded at the contact positions of the main beam and the columns on both sides to prevent the left and right displacement of the main beam.

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