CN115573738A - Construction process for guiding and entering tunnel in tunnel outlet - Google Patents
Construction process for guiding and entering tunnel in tunnel outlet Download PDFInfo
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- CN115573738A CN115573738A CN202211145129.2A CN202211145129A CN115573738A CN 115573738 A CN115573738 A CN 115573738A CN 202211145129 A CN202211145129 A CN 202211145129A CN 115573738 A CN115573738 A CN 115573738A
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- 238000000034 method Methods 0.000 title claims abstract description 58
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- 229910000831 Steel Inorganic materials 0.000 claims abstract description 39
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- 239000004567 concrete Substances 0.000 claims abstract description 21
- 238000005507 spraying Methods 0.000 claims abstract description 19
- 238000005553 drilling Methods 0.000 claims abstract description 13
- 238000005422 blasting Methods 0.000 claims abstract description 8
- 230000003014 reinforcing effect Effects 0.000 claims abstract description 8
- 239000002893 slag Substances 0.000 claims description 16
- 239000011378 shotcrete Substances 0.000 claims description 11
- 230000032258 transport Effects 0.000 claims description 10
- 229910001294 Reinforcing steel Inorganic materials 0.000 claims description 6
- 239000011440 grout Substances 0.000 claims description 6
- 238000013461 design Methods 0.000 claims description 4
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Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
- E21D11/105—Transport or application of concrete specially adapted for the lining of tunnels or galleries ; Backfilling the space between main building element and the surrounding rock, e.g. with concrete
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
- E21D11/107—Reinforcing elements therefor; Holders for the reinforcing elements
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/14—Lining predominantly with metal
- E21D11/18—Arch members ; Network made of arch members ; Ring elements; Polygon elements; Polygon elements inside arches
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D20/00—Setting anchoring-bolts
Abstract
The invention discloses a pilot tunnel entrance construction process in a tunnel exit, which comprises the following steps: s1, excavating a section profile and lofting; s2, pre-supporting a small conduit and grouting; s3, excavating and primary supporting of the middle pilot tunnel: adopting a step method construction and annular excavation to leave a core soil method to excavate a pilot tunnel along the extension direction of the tunnel, and forming a primary support structure at the vault of the pilot tunnel, wherein the excavation method mainly adopts mechanical excavation and is assisted by a drilling and blasting method, and top support comprises the following steps: the method comprises the steps of firstly spraying concrete, embedding prestressed long anchor rods, hanging reinforcing mesh, installing steel arch frames, and spraying concrete to the designed thickness. The construction process effectively reduces the difficulty and potential safety hazards of tunnel construction, improves the engineering quality, reduces the occurrence of common quality problems, and can effectively avoid various disasters such as cracking, block falling, arch frame deformation, inverted arch bottom bulging, collapse and roof collapse of the supporting layer.
Description
Technical Field
The invention relates to the technical field of tunnel construction, in particular to a pilot tunnel entrance construction process in a tunnel exit.
Background
Tunnel easily is under construction in the rock landform of erecting admittedly, nevertheless if belong to denudation hilly mountain land landform, the topography fluctuation is great, and the joint is developed, and the crack is more, and a large amount of laterite presss from both sides pumice, boulder, layering are more, and soil stone handing-over presss from both sides mud, black mudstone irregular distribution, and is great to rock mass stability influence, leads to appearing more geological disasters.
The tunnel construction is carried out on the landform, so that the difficulty and potential safety hazards of the tunnel construction are increased, the cost investment is increased, the construction period is delayed, and if the tunnel is supported in the primary supporting mode according to the traditional tunnel, after the primary supporting construction is completed, a supporting layer is prone to cracking, dropping blocks, deformation of an arch frame, inverted arch bottom bulging, collapse, roof collapse and other disasters, so that the construction difficulty is increased rapidly, and how to effectively prevent and reduce the influence of geological disasters on the construction is a problem which needs to be solved urgently.
Disclosure of Invention
The invention aims to provide a pilot tunnel entry construction process in a tunnel outlet, which can effectively prevent geological disasters of large and weak surrounding rock tunnels, ensure tunnel construction and operation safety, reduce economic losses caused by the geological disasters, and has the advantages of low construction resources and cost, easiness in construction, high construction speed, small safety risk and high construction quality.
The purpose of the invention can be realized by the following technical scheme:
a pilot tunnel entering construction process in a tunnel outlet comprises the following steps:
s1, excavation section profile lofting
Directly setting a total station on a control center line point in a hole, inputting the working face mileage and the instrument elevation into a programming computer to determine the center of the arch part of the working face, and releasing an excavation contour line according to the center;
s2, forepoling small conduit and grouting
A measuring worker accurately marks the hole position of the circulating small guide pipe on the excavation section according to a construction drawing, a pneumatic drill is used for drilling, after the drilling is finished, the small guide pipe is arranged in the drill hole according to an external insertion angle of 10-15 degrees by using a drilling and driving method, then a hole valve is screwed on the pipe opening of the small guide pipe, a grouting pipeline is connected, and grouting is carried out by using a grouting pump according to a method that the grouting amount is first large and then small from bottom to top, the grout is first diluted and then concentrated;
s3, excavating and primary supporting of middle pilot tunnel
Excavating a middle pilot tunnel along the extension direction of the tunnel by adopting a step method construction and annular excavation core soil remaining method, and forming a primary support structure at the vault of the middle pilot tunnel, wherein the excavation method mainly adopts mechanical excavation and assists a drilling and blasting method;
s4, removing slag of transport vehicle
The constructor uses a transport vehicle to transport the waste slag generated by excavating the middle pilot tunnel to a specified piling place through the filled access roads and the existing village roads.
As a further scheme of the invention: the top is strutted in S3 and is included: the method comprises the following steps of firstly spraying concrete, embedding a prestressed long anchor rod, hanging a reinforcing mesh, installing a steel arch frame, and spraying concrete again to reach the designed thickness.
As a further scheme of the invention: the construction process of the method for retaining the core soil by annular excavation in the S2 comprises the following steps: the method comprises the steps of firstly excavating from the top of an annular part of an upper step of a pilot tunnel to two sides, forming primary support on a vault in time after excavation, and excavating arc parts on two sides of a lower step, upper step core soil and lower step core soil in sequence after the strength of concrete reaches 70% of the design strength.
As a further scheme of the invention: the excavation footage of the annular part is 0.6-1.2 m, the height of the upper step is 2.5m, and the area of the core soil of the upper step and the core soil of the lower step is not less than 50% of the area of the whole section.
As a further scheme of the invention: the thickness of the primary sprayed concrete is controlled to be 4-6 cm, the vault is not more than 10cm and the side wall is not more than 15cm during secondary spraying.
As a further scheme of the invention: and S3, the leading small conduit is processed and manufactured by adopting a hot-rolled seamless steel pipe, the front end of the steel pipe is processed into a cone, a reinforcing steel bar stiffening hoop is welded at the tail part, grouting holes are drilled at the periphery of the pipe wall, and the tail part is welded at the belly part of the steel arch frame at 13 times in a circulation mode.
The invention has the beneficial effects that:
1. the method comprises the steps of constructing by a step method and excavating the annular to leave the core soil, excavating the middle pilot tunnel along the extension direction of the tunnel, preferably excavating from the top of the annular part of the upper step of the middle pilot tunnel to two sides, and forming a primary supporting structure immediately following the vault of the middle pilot tunnel in time.
2. The early-stage supporting structure formed by the early-stage spraying concrete → the embedded prestressed long anchor rod → the steel bar hanging mesh → the installed steel arch → the repeated spraying concrete to the designed thickness can effectively avoid various disasters such as cracking, dropping block, arch deformation, inverted arch bottom bulging, collapse and roof caving of the supporting layer.
Drawings
The invention will be further described with reference to the accompanying drawings.
FIG. 1 is a schematic view of a pilot tunnel structure according to the present invention;
FIG. 2 is a schematic view of the construction process of the present invention;
FIG. 3 is a schematic flow chart of the present invention for creating primary supports.
In the figure: 1. a middle pilot hole; 2. primary support; 3. an upper step; 4. an annular portion; 5. a small catheter; 6. descending a step; 7. an arcuate portion; 8. core soil for going up steps; 9. and (5) core soil of the lower step.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Before the tunnel is excavated, in order to meet the requirements of tunnel construction and ensure all-weather smoothness of the sidewalk, construction sidewalks are built near the tunnel outlet, construction is carried out and hardening treatment is carried out on the construction sidewalks, and an anti-collision fence and a speed-limiting marker light identification label are arranged at the exit and two sides of each sidewalk.
Referring to fig. 1-3, a construction process for guiding and entering a tunnel at a tunnel exit includes the following steps:
1. opening side and upward slope excavation
The center line and the excavation side line are discharged according to the design drawing in the excavation of the opening side and the upward slope, loose slag and other sundries on the excavation surface are removed, the reverse construction method is adopted, the anchor is sprayed firstly, the slope is downwards placed step by step, the top and the bottom adopt a manual matching excavator to carry out the excavation, and the vertical operation and the excavation bottom excavation are strictly forbidden.
An excavator and a loader are matched for loading slag, and a dump truck transports the slag to a slag disposal site. In order to ensure the smoothness and stability of the side slope and avoid excessive and underexcavation and excessive disturbance to the side slope as much as possible, blasting excavation is controlled by strictly controlling blasting parameters. And (3) carrying out layered excavation on the side slope and the top slope, controlling the slope ratio, reserving the slope surface thickness of 20-30 cm during mechanical excavation, and manually repairing the slope and removing the deficient soil. The side and upward slopes should be checked at any time during excavation, if sliding, cracking and other phenomena occur, the slope is properly relieved, stability and construction safety of the side and upward slopes are guaranteed, and the side and upward slopes are protected by anchor rod frame beams and arch-shaped frameworks.
2. Excavation section profile lofting
The total station is directly arranged on a control center line point in a hole, the working face mileage and the instrument elevation are input into a programming computer to determine the center of the arch part of the working face, the excavation contour line is released accordingly, constructors mark the contour line with red paint, subsequent construction is facilitated, the excavation contour line needs to be accurately marked during measurement and lofting, the excavation section is well controlled in the excavation process, and measurement is accurate.
3. Forepoling small conduit 5 and grouting
The measuring personnel accurately mark the hole position of the circulating small guide pipe 5 on the excavated section according to a construction drawing, and set necessary control points so as to control the external insertion angle and direction of the small guide pipe 5 during drilling, then drill holes by using a pneumatic drill, after the drilling is finished, use a drilling and driving method to press the external insertion angle to be 10-15 degrees, install the small guide pipe 5 in the drill hole, weld the tail part of each small guide pipe 5 with the corresponding steel arch belly part to strengthen the common supporting function, after the small guide pipe 5 is installed, use plastic cement or anchoring agent to seal the hole opening and peripheral cracks, screw the hole opening valve on the pipe opening of the small guide pipe 5, connect a grouting pipeline, use a grouting pump to perform grouting according to the method that the grout is diluted from bottom to top, the grout is concentrated, the grouting amount is increased first and then the grout is decreased, and the hole is isolated and grouted when the grout is mixed or run. Before grouting, a grouting system is required to run in a trial mode, grouting parameters such as reasonable slurry proportion (designed as 1 cement slurry) and grouting pressure are determined in a test before grouting, the grouting amount and the grouting pressure are used as the standard for finishing the standard, the stability of surrounding rock is enhanced after grouting, the stability of the surrounding rock in 2 time after excavation and primary support is finished is facilitated, and the surrounding rock is not damaged by instability until collapse.
The small guide pipe 5 is made of a hot-rolled seamless steel pipe with the diameter of 42mm and the wall thickness of 4mm, the length of a single pipe is 4.5m, the front end of the steel pipe is processed into a cone, the tail part of the steel pipe is welded with a reinforcing steel bar stiffening hoop with the diameter of 16mm, and grouting holes with the diameter of 6mm are drilled on the periphery of the pipe wall.
The arrangement condition of the small guide pipes 5 is determined according to the actual surrounding rock level, if V-level surrounding rock exists, 13 small guide pipes 5 are arranged in each cycle, the circumferential distance of the steel pipes is 40cm, and the longitudinal row distance is 3m.
4. Excavation and primary support formation 2 of middle pilot tunnel 1
After excavation preparation work is done, excavating a middle pilot tunnel 1 along the extension direction of the tunnel by adopting a step method construction and annular excavation core soil remaining method, and forming a primary support 2 at the vault of the middle pilot tunnel 1, wherein the excavation method mainly adopts mechanical excavation and assists a drilling and blasting method;
the middle pilot tunnel 1 can be divided into a plurality of steps for construction as required, the steps are not suitable for being layered, the middle pilot tunnel is divided into an upper step 3 and a lower step 6 in the example, the upper step 3 is provided with an annular part 4 and upper step core soil 8, the lower step 6 is provided with arc parts 7 at two sides and lower step core soil 9, the length of the steps is not suitable to exceed 1.5 times of the tunnel excavation width, and the height of the upper step 3 is preferably about 2.5 m; during construction, firstly, the annular part 4 of the upper step 3 of the middle pilot tunnel 1 is excavated towards two sides, the excavation footage is preferably 0.6-1.2 m, a slag loading machine closely follows the excavation surface to reduce the slag skimming distance, during excavation, whether net-jet support is needed or not can be confirmed according to the surrounding rock conditions on two sides of the middle pilot tunnel 1, when the surrounding rock is poor, a steel wire net with the diameter of 3-4mm is adopted for net-jet support, the effect of sealing the surrounding rock is only achieved, the two side straight walls are prevented from falling blocks, and convenience is brought to later-stage excavation without independent dismantling.
After excavation, the arch crown is timely excavated through the primary concrete injection → the embedded prestressed long anchor rod → the steel mesh suspension → the steel arch frame installation → the secondary concrete injection to the designed thickness to form the primary support 2, and after the concrete strength reaches 70% of the designed strength, the arc parts 7 at the two sides of the lower step 6, the upper step core soil 8 and the lower step core soil 9 are sequentially excavated in sequence.
After excavation is finished, concrete is firstly sprayed for the first time, the thickness of the concrete for the first time is 4-6 cm, a prestressed long anchor rod is buried in a vault borehole with the diameter of 22mm after the concrete for the first time is sprayed for the first time, and holes of anchor rod holes are arranged according to the requirements of construction drawings. The reinforcing mesh is installed after the anchor rod is constructed, the space between the V-level surrounding rock reinforcing mesh is 20cm multiplied by 20cm, the reinforcing mesh is paved along with the sprayed surface in an up-and-down mode, and the gap between the reinforcing mesh and the sprayed surface is preferably controlled to be 20 mm-30 mm. The joints are bound by thin iron wires or spot-welded together, so that the reinforcing mesh does not shake during spraying. The lapping length of the reinforcing steel bars is not less than 35 times of the diameter of the reinforcing steel bars and not less than the size of a long edge of a grid, the thickness of a sprayed concrete protective layer of the reinforcing steel bar grid is not less than 2cm, and when the concrete is sprayed, in order to ensure that the net piece and the rock wall surface are sprayed compactly, a spray head is slightly inclined. The method comprises the steps of firstly spraying concrete before pre-burying the long prestressed anchor rods, and secondly spraying the concrete to the designed thickness after the long prestressed anchor rods are buried, so that the long prestressed anchor rods can be buried in top surrounding rocks more tightly, the span reducing effect is improved, the thickness of the firstly sprayed concrete is controlled to be 4-6 cm, the vault cannot be larger than 10cm and the side wall cannot be larger than 15cm during repeated spraying, a nozzle is perpendicular to a rock surface during concrete spraying operation, the distance between a spraying gun head and a spraying surface is 0.6-1.2 m, and the working pressure of a sprayer is controlled to be 0.1-0.15 Mpa.
The V-level surrounding rock steel arch frame adopts I18I-shaped steel, and the longitudinal distance is 0.5m. The size of the assembled steel frame meets the requirement, the arc is smooth, and the peripheral contour error is not more than 3cm; all units are connected by bolts, and the tolerance of the center distance of bolt holes does not exceed +/-0.5 mm; when the steel frames are flatly placed, the plane warping is less than +/-2 cm, the steel frame segments of each roof truss need to be numbered, the section steel webs and the wing plates have no warping deformation, and the section steel webs and the wing plates can be transported into a hole for use after being checked to meet the requirements;
the steel arch frame is preferably installed after primary spraying, the outline, the center line and the elevation of the excavation section are checked before installation, the steel frame is close to the primary spraying surface as far as possible when installed, and a wedge block is used for wedging when a gap exists; the arch springing is arranged on a firm foundation, the lower part of the bottom leg is provided with virtual slag to be removed, the over-digging part is filled with sprayed concrete, the steel arch is installed in sections, the plane of the connecting steel plate is perpendicular to the axis of the steel arch, and the number of the bolts of the two connecting steel plates is not less than 4. The steel arch should be perpendicular to the tunnel central line, vertical not slope, plane dislocation not, do not distort. The allowable deviation of the upper part, the lower part, the left part and the right part is +/-5 cm, the inclination of the steel arch frame is less than 2 degrees, and after the steel arch frame is installed in place, a gap between a steel frame and a primary spraying surface is densely filled with sprayed concrete. The sprayed concrete is symmetrically sprayed upwards from arch feet on two sides and covers the steel frame, and the thickness of the sprayed concrete protective layer on the side close to the air is not less than 2cm.
5. Slag removal for transport vehicle
The method comprises the steps that a constructor transports waste residues generated by excavation of a middle pilot tunnel 1 to a specified piling place through a filled access road and an existing village road by a transport vehicle, whether an illumination system, a whistle system, a steering system and a braking system of a loader are normal or not is checked before operation, abnormal conditions such as excavation face surrounding rock conditions and block falling are checked before slag loading, or abnormal conditions of the surrounding rock are found in the slag loading process, slag loading operation can be carried out after slag loading is stopped and danger elimination is carried out, when slag is unloaded, tipping bucket operation outside a cab is strictly prohibited, station people are strictly prohibited in the tipping bucket, the tipper is strictly prohibited while backing up or the tipper is started in a jerking and retreating process, whether wires exist above the tipper is required to be inspected when the tipper is lifted up, the tipper is strictly prohibited in an upward turning state, the tipper is driven in the hole, lamps are required to be turned on, and the speed is not more than 15Km/h. The reversing and steering in the tunnel are required to turn on lights, whistle, and warning and prompting signs are arranged on the tunnel opening, the level crossing and the narrow construction site, and personnel are arranged to command traffic when necessary.
The method comprises the steps of excavating a middle pilot tunnel 1 along the extension direction of the tunnel by adopting a step method construction and annular excavation core soil remaining method, preferably excavating from the top of an annular part 4 of an upper step 3 of the middle pilot tunnel 1 to two sides, and forming a primary support 2 by following the vault of the middle pilot tunnel 1 in time, wherein the excavation method is mainly mechanical excavation and assisted by a drilling and blasting method, and after the strength of concrete reaches 70% of the design strength, sequentially excavating an arc part 7 at two sides of a lower step 6, upper step core soil 8 and lower step core soil 9, so that the difficulty and potential safety hazard of tunnel construction are effectively reduced, the engineering quality is improved, and the occurrence of common quality diseases is reduced.
The primary support 2 formed by the primary sprayed concrete → the embedded prestressed long anchor rod → the steel bar net → the installed steel arch frame → the secondary sprayed concrete to the designed thickness can effectively avoid various disasters such as cracking, block falling, arch frame deformation, inverted arch bottom bulging, collapse and roof falling of a support layer.
The basic principles of 'pipe advancing, tight grouting, weak blasting, short excavation, strong supporting, duty measurement and early sealing' are strictly followed in construction.
While one embodiment of the present invention has been described in detail, the description is only a preferred embodiment of the present invention and should not be taken as limiting the scope of the invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.
Claims (6)
1. A pilot tunnel entering construction process in a tunnel outlet is characterized by comprising the following steps:
s1, excavation section profile lofting
Directly setting a total station on a control center line point in a hole, inputting the working face mileage and the instrument elevation into a programming computer to determine the center of the arch part of the working face, and releasing an excavation contour line according to the center;
s2, a small advanced support conduit (5) and grouting
A measurer accurately marks hole positions of the circulating small guide pipes (5) on an excavated section according to construction drawings, drills holes by using a pneumatic drill, installs the small guide pipes (5) in the drilled holes by using a drilling and driving method according to an external insertion angle of 10-15 degrees after the drilling is finished, then screws an orifice valve on the orifice of the small guide pipes (5), connects grouting pipelines, and performs grouting by using a grouting pump according to a method that the grouting amount is first large and then small from bottom to top, the grout is first diluted and then concentrated, and the grouting amount is first large and then small;
s3, excavating middle pilot tunnel (1) and forming primary support (2)
Excavating a middle pilot tunnel (1) along the extending direction of the tunnel by adopting a step method construction and annular excavation core soil remaining method, and forming a primary support (2) at the vault of the middle pilot tunnel (1), wherein the excavating method mainly adopts mechanical excavation and is assisted by a drilling and blasting method;
s4, removing slag of the transport vehicle
And the constructor transports the waste slag generated by excavating the middle pilot tunnel (1) to a specified piling place by the transport vehicle through the filled access road and the existing village road.
2. The construction process of the pilot tunnel into the tunnel in the tunnel exit according to claim 1, wherein the top support in the S3 comprises: the method comprises the steps of firstly spraying concrete, embedding prestressed long anchor rods, hanging reinforcing mesh, installing steel arch frames, and spraying concrete to the designed thickness.
3. The construction process for guiding and entering the tunnel in the tunnel outlet according to claim 2, wherein the construction process of the method for retaining the core soil by annular excavation in S2 is as follows: the method comprises the steps of firstly excavating from the top of an annular part (4) of an upper step (3) of a pilot tunnel (1) to two sides, forming primary supports (2) on vault tops in time after excavation, and excavating arc parts (7) on two sides of a lower step (6), upper step core soil (8) and lower step core soil (9) in sequence after concrete strength reaches 70% of design strength.
4. The construction process of the pilot tunnel into the tunnel in the tunnel outlet according to claim 3, characterized in that the excavation footage of the annular part (4) is 0.6-1.2 m, the height of the upper step (3) is 2.5m, and the area of the core soil (8) of the upper step and the core soil (9) of the lower step is not less than 50% of the area of the whole tunnel section.
5. The construction process of the pilot tunnel entering in the tunnel exit according to claim 2, characterized in that the thickness of the primary shotcrete is controlled to be 4-6 cm, the vault is not more than 10cm and the side wall is not more than 15cm during the secondary shotcrete.
6. The construction process of the pilot tunnel into the tunnel in the tunnel outlet according to claim 1, characterized in that the small duct (5) in S3 is made of hot-rolled seamless steel tube, the front end of the steel tube is made into a cone, the tail part is welded with a reinforcing steel bar stiffening hoop, grouting holes are drilled on the periphery of the tube wall, and the tail part is welded to the belly part of the steel arch every 13 times.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211145129.2A CN115573738A (en) | 2022-09-20 | 2022-09-20 | Construction process for guiding and entering tunnel in tunnel outlet |
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| CN202211145129.2A CN115573738A (en) | 2022-09-20 | 2022-09-20 | Construction process for guiding and entering tunnel in tunnel outlet |
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060165489A1 (en) * | 2002-11-22 | 2006-07-27 | Dong-Hyun Seo | Structure of intermediate wall of three arch excavated tunnel and method for constructing the same |
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