CN115030731A - Pilot tunnel construction method in cross tunnel engineering - Google Patents
Pilot tunnel construction method in cross tunnel engineering Download PDFInfo
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- CN115030731A CN115030731A CN202210723800.0A CN202210723800A CN115030731A CN 115030731 A CN115030731 A CN 115030731A CN 202210723800 A CN202210723800 A CN 202210723800A CN 115030731 A CN115030731 A CN 115030731A
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- 238000010276 construction Methods 0.000 title claims abstract description 46
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 102
- 239000010959 steel Substances 0.000 claims abstract description 102
- 238000000034 method Methods 0.000 claims abstract description 50
- 239000004567 concrete Substances 0.000 claims abstract description 45
- 238000005553 drilling Methods 0.000 claims abstract description 30
- 238000003466 welding Methods 0.000 claims abstract description 20
- 230000008093 supporting effect Effects 0.000 claims abstract description 15
- 238000009434 installation Methods 0.000 claims abstract description 10
- 210000001015 abdomen Anatomy 0.000 claims abstract description 9
- 239000004570 mortar (masonry) Substances 0.000 claims abstract description 9
- 230000002093 peripheral effect Effects 0.000 claims abstract description 8
- 239000004575 stone Substances 0.000 claims abstract description 7
- 239000004568 cement Substances 0.000 claims abstract description 6
- 238000005507 spraying Methods 0.000 claims abstract description 6
- 239000002689 soil Substances 0.000 claims abstract description 5
- 239000002893 slag Substances 0.000 claims abstract description 4
- 238000007664 blowing Methods 0.000 claims abstract description 3
- 230000002787 reinforcement Effects 0.000 claims abstract description 3
- 239000004576 sand Substances 0.000 claims abstract description 3
- 239000011378 shotcrete Substances 0.000 claims abstract description 3
- 239000011435 rock Substances 0.000 claims description 52
- 238000009412 basement excavation Methods 0.000 claims description 45
- 238000005422 blasting Methods 0.000 claims description 15
- 229910001294 Reinforcing steel Inorganic materials 0.000 claims description 10
- 238000003780 insertion Methods 0.000 claims description 9
- 230000037431 insertion Effects 0.000 claims description 9
- 239000002002 slurry Substances 0.000 claims description 9
- 238000009415 formwork Methods 0.000 claims description 7
- 238000009826 distribution Methods 0.000 claims description 6
- 238000005192 partition Methods 0.000 claims description 6
- 238000005259 measurement Methods 0.000 claims description 4
- 238000012544 monitoring process Methods 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 4
- 230000001680 brushing effect Effects 0.000 claims description 3
- 238000004140 cleaning Methods 0.000 claims description 3
- 239000012459 cleaning agent Substances 0.000 claims description 3
- 238000007667 floating Methods 0.000 claims description 3
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims description 3
- 239000006082 mold release agent Substances 0.000 claims description 3
- 239000011241 protective layer Substances 0.000 claims description 3
- 230000003014 reinforcing effect Effects 0.000 claims description 2
- 238000013461 design Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 239000011440 grout Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 238000007596 consolidation process Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 238000004873 anchoring Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 238000004078 waterproofing Methods 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK 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
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK 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
- E21D11/15—Plate linings; Laggings, i.e. linings designed for holding back formation material or for transmitting the load to main supporting members
- E21D11/152—Laggings made of grids or nettings
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK 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 OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D20/00—Setting anchoring-bolts
- E21D20/02—Setting anchoring-bolts with provisions for grouting
- E21D20/021—Grouting with inorganic components, e.g. cement
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/003—Arrangement of measuring or indicating devices for use during driving of tunnels, e.g. for guiding machines
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/006—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries by making use of blasting methods
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F17/00—Methods or devices for use in mines or tunnels, not covered elsewhere
- E21F17/103—Dams, e.g. for ventilation
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/20—Hydro energy
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- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Structural Engineering (AREA)
- Architecture (AREA)
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Abstract
The invention discloses a pilot tunnel construction method in cross tunnel engineering, which comprises the following steps: the method comprises the following steps: measuring lofting, and measuring the position of the anchor rod according to a drawing; step two: drilling, namely drilling by adopting a drilling driving method, blowing sand and stones out of holes after hole forming, and then jacking the grouting pipe into the drilled holes; step three: grouting, welding the tail of a grouting pipe fitting to the steel arch belly for supporting, plugging an orifice and peripheral cracks by using plastic cement after installation, and spraying C25 concrete with the thickness of 15cm near the small guide pipe and on the working surface to prevent the working surface from collapsing; step four: after the pilot tunnel is excavated, performing surface reinforcement on the primary sprayed concrete on the inner wall of the pilot tunnel to avoid collapse and soil falling; step five: supporting a mortar anchor rod, wherein the hole of an anchor rod hole is arranged according to the requirement of construction drawing, and the drilling position is arranged in the range of 2.0m above the bottom; step six: mounting the steel arch after hanging the net on the inner wall of the pilot tunnel, and spraying concrete again after the steel arch is mounted; step seven: and (6) removing slag.
Description
Technical Field
The invention relates to the technical field of tunnel construction, in particular to a pilot tunnel construction method in cross tunnel engineering.
Background
In the construction of the double-arch tunnel, a three-pilot-hole construction process is adopted in the early stage, but the construction process has the disadvantages of large disturbance on surrounding rocks at the tunnel entrance, long construction period, limited construction efficiency, high construction cost, difficult tunnel waterproofing and easy water leakage. The medium pilot tunnel construction process belongs to a relatively advanced and efficient construction method, and is a tunnel entering construction process for excavating a large section by adopting smooth blasting on the basis of a new Austrian's Law principle. Meanwhile, auxiliary technologies such as anchoring, spraying, net, steel arch frames and advanced ducts can be combined, through-going pilot tunnels are excavated, partition wall concrete is poured, then the main tunnels are excavated through a step method, and secondary lining is carried out simultaneously after excavation is finished, so that the efficiency and the quality of double-arch tunnel entrance can be effectively guaranteed, the disturbance on surrounding rock operation is small, the construction effect is good, and the method has good popularization and application values.
The tunnel portal section buries deeply, and the roof is thin, and upper strata mainly is rubble soil, clay, strong weathering layer, and thickness is uneven, and the morals and manners are uneven, and the tunnel mainly passes through the broken area of joint simultaneously, and the country rock self-stability is poor. The V-level surrounding rock cavern top is easy to have the phenomena of block falling, collapse, roof collapse and the like; grade IV surrounding rock may fall. There is a greater safety risk in construction.
Disclosure of Invention
The invention aims to solve the problems of the background technology and provides a pilot tunnel construction method in cross tunnel engineering.
The purpose of the invention can be realized by the following technical scheme:
a pilot tunnel construction method in cross tunnel engineering comprises the following steps:
the method comprises the following steps: measuring lofting, and measuring the position of the anchor rod according to a drawing;
step two: drilling, namely drilling by adopting a drilling driving method, blowing sand and stones out of holes after hole forming, and then jacking the grouting pipe into the drilled holes;
step three: grouting, welding the tail part of the grouting pipe fitting to the steel arch belly for supporting, plugging the orifice and peripheral cracks with plastic cement after installation, and spraying C25 concrete with the thickness of 15cm near the small guide pipe and on the working surface to prevent the working surface from collapsing;
step four: after the pilot tunnel is excavated, performing surface reinforcement on the primary sprayed concrete on the inner wall of the pilot tunnel to avoid collapse and soil falling;
step five: supporting a mortar anchor rod, wherein the hole of an anchor rod hole is arranged according to the requirement of construction drawing, and the drilling position is arranged in the range of 2.0m above the bottom;
step six: after the net is hung on the inner wall of the pilot tunnel, the steel arch is installed, and concrete is sprayed again after the steel arch is installed;
step seven: and (6) removing slag.
As a further scheme of the invention: the V-level surrounding rock arch part grouting pipe fitting is a small guide pipe, a grouting hole with the diameter of 8mm is drilled in the steel pipe body, the external insertion angle is 10-15 degrees, and the tail part of the grouting pipe fitting is welded to the steel arch belly part to enhance the common supporting function; a ring is arranged every 4 trusses, and the overlapping length of the pipes is 1.46 m; after hole distribution is measured, the rock drill is aligned to the hole position, and holes are drilled according to an external insertion angle of 10-15 degrees by taking a steel frame close to an excavation surface as a fulcrum.
As a further scheme of the invention: the IV-level surrounding rock arch part grouting pipe fitting is a phi 25 hollow grouting anchor rod, the length of the grouting pipe fitting is 3.5m, the tail part of the grouting pipe fitting is welded to a steel arch belly part to enhance the common supporting effect, a ring is arranged every 2 pieces, and the grouting pipe fitting is longitudinally lapped by 1.38 m; after hole distribution is measured, the rock drill is aligned with the hole position, and holes are drilled according to an external insertion angle of 10-15 degrees by taking a steel frame close to the excavation surface as a fulcrum.
As a further scheme of the invention: the excavation mode is mainly a drilling and blasting method and is assisted by manual pneumatic pick excavation; according to the actual situation of surrounding rocks, the geology is better, and the actual excavation circulating footage of the IV-level surrounding rocks is not more than 2.0 m; carrying out low-light-level blasting by adopting a drilling and blasting method; the hole positions of the drill holes are determined according to the measured central line, the measured waist line and the measured excavation contour line; the peripheral holes are drilled on the profile line of the section, the deviation of the hole sites of the cut holes and the adjustment range along the profile line is less than 5cm, and the deviation of the hole sites of other blast holes is less than 100 mm.
As a further scheme of the invention: the pilot tunnel excavation method mainly adopts manual pneumatic pick excavation and adopts a drilling and blasting method as assistance. The excavation also adopts an upper step excavation method and a lower step excavation method, and the excavation mode of the pilot tunnel can be properly adjusted according to the monitoring measurement data.
As a further scheme of the invention: the bottom of the steel arch frame is arranged on a solid foundation, when the bearing capacity of the foundation cannot meet the requirement, foundation hardening is required, and broken stone or concrete is laid for hardening so as to ensure the stability of the steel arch frame; the steel arch frame is erected to ensure that the steel arch frame is tightly close to the surrounding rock wall, a backing plate is arranged when a large gap exists between the steel arch frame and the surrounding rock, and an A6 type steel bar welding net (20 multiplied by 20cm) is welded between the steel arch frames to prevent the rock from falling.
As a further scheme of the invention: the method further comprises the following steps of constructing the intermediate wall: the method comprises the following steps: measuring, namely measuring the position of the intermediate wall according to a drawing; step two: reinforcing the foundation of the grouting pipe fitting; step three: binding steel bars; step four: erecting a formwork, and installing a formwork after the binding and installation of the steel bars are finished; step five: pouring, namely pouring by adopting concrete; step six: vibrating and maintaining.
As a further scheme of the invention: protective layers of all circumferential reinforcing steel bars of the intermediate wall are 6.0cm, the arch foot plate of the primary support steel arch frame of the main tunnel is connected with the embedded steel plate in a welding mode, and the height of a welding seam is 10 mm; firstly, mounting circumferential reinforcing steel bars phi 25 (phi 22 for IV-level surrounding rock) at the position of an intermediate wall, arranging at intervals of 20cm (25 cm for IV-level surrounding rock), binding longitudinal reinforcing steel bars phi 12 after welding stirrups, and arranging at intervals of 20cm and adopting binding wires for connection; and finally welding the tie bar phi 12 steel bars at a distance of 20 cm.
As a further scheme of the invention: the intermediate wall is poured to the top by a trolley at one time, and the template is a large customized steel template (connected by bolts); before installation, the template is firstly subjected to rust removal, cleaning and mold release agent brushing, and then is installed; in the assembling process, temporary support is added, section steel is used as a framework after the assembling is finished, and the templates on the two sides are pulled oppositely by pull rods so as to ensure the firmness of the templates in the concrete pouring process; after the trolley is in place, the stability of the trolley is positioned and reinforced by using a middle pilot tunnel steel frame support, and then concrete pouring is carried out; the longitudinal length of each operation section is not more than 6 m; the middle partition wall concrete must be tightly propped against the guide hole and is densely backfilled.
As a further scheme of the invention: the vibrating duration time of each vibrating point in the construction process is 20-30s, and the concrete stops sinking and does not generate bubbles, and the surface of the concrete presents floating slurry; pouring lining concrete by using a high-pressure concrete delivery pump to ensure that the concrete at the arch crown part is compact; when concrete is poured, reserving a grouting hole every 5m of the arch top of the intermediate wall, and grouting the non-compact part; when the embedded pipe fittings are manufactured and installed, strictly measuring and setting out, and controlling the elevation and the plane position; and the connection between the embedded pipe fittings is processed.
The invention has the beneficial effects that:
by using a construction operation method which is different in V-grade and IV-grade and has pertinence, V-grade advanced support small guide pipes, manual air pick excavation and the like are assisted with IV-grade advanced support hollow anchor rods and a drilling and blasting method for the manual air pick excavation, so that the phenomena of block falling, collapse, roof falling and the like of V-grade surrounding rock holes can be avoided; and the IV-level surrounding rock falls off. The construction safety is greatly improved.
Drawings
The invention will be further described with reference to the accompanying drawings.
Fig. 1 is a schematic view of a steel arch construction.
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.
In the first embodiment, excavation of V-level surrounding rock:
measuring and lofting: the position of the small pipe in advance is measured according to a drawing, the length of a single small pipe with the diameter of 42 multiplied by 4mm is 4m, and the circumferential distance of the steel pipes is 40 cm.
The circular advancing ruler Va is 0.6m by adopting a drilling method.
The diameter of a drilled hole is 3-5 mm larger than that of the steel pipe, after the hole is formed, gravel in the hole is blown out by high-pressure air, then the small guide pipe is hammered or jacked in by a drilling machine, the jacking length is larger than 90% of the length of the steel pipe, and the gravel in the steel pipe is blown out by a high-speed fan.
The V-level surrounding rock arch part advanced support uses a small guide pipe, a grouting hole with the diameter of 8mm is drilled in the steel pipe body, the external insertion angle is 10-15 degrees, and the tail part is welded to the steel arch belly part to enhance the common support effect.
A ring was placed every 4 trusses, and the pipe lap length was 1.46 m. After hole distribution is measured, the rock drill is aligned with the hole position, and holes are drilled according to an external insertion angle of 10-15 degrees by taking a steel frame close to the excavation surface as a fulcrum.
After the small guide pipe is installed, plastic cement is used for sealing the hole opening and peripheral cracks, and C25 concrete with the thickness of 15cm is sprayed near the small guide pipe and on the working surface to prevent the working surface from collapsing.
The small conduit pipe mouth is screwed with the orifice valve, is connected with a grouting pipeline, is grouted by a grouting pump according to the method that the grout is thin first and then thick, the grouting amount is large first and then small, and is isolated from the hole for grouting when the grout is mixed or leaked.
Before grouting, a grouting system needs to be operated in a trial mode, and before grouting, a test is carried out to determine grouting parameters such as reasonable slurry proportion (designed as 1:1 cement slurry), grouting pressure and the like; and (4) finishing the standard by mainly controlling the grouting amount and performing final pressure check.
And (4) effect checking: excavating and checking the penetration and consolidation conditions of the slurry; analyzing and judging according to a pressure/pulp quantity curve; when the design requirement is not met, a small catheter needs to be additionally arranged.
The pilot tunnel excavation method mainly adopts manual pneumatic pick excavation and adopts a drilling and blasting method as assistance.
According to the excavation condition of the side and the top slope of the opening, advanced prediction is made to ensure the construction safety.
The excavation also adopts an upper step excavation method and a lower step excavation method, and the excavation mode of the pilot tunnel can be properly adjusted according to the monitoring measurement data.
And (5) supporting the hole body by using a mortar anchor rod.
The holes of the anchor rod holes are arranged according to the requirements of construction drawings, the drilling positions are arranged in the range of 2.0m above the bottom, the longitudinal and circumferential spacing is 60 multiplied by 100cm, and the hole position deviation is less than 100 mm.
The hole axis direction of the anchor rod hole meets the requirements of construction drawings, and the hole axis direction of the anchor rod of the system is vertical to the excavation surface (a phi 22 mortar anchor rod with the length of 3m is adopted, and the material and specification meet the design requirements).
And (5) supporting the tunnel body by using a steel arch frame.
The steel arch frame is made of I16I-shaped steel, and the longitudinal distance is 0.6 m.
And (4) after the steel arch frame is processed in a steel bar field, conveying the steel arch frame to the site, and performing on-site bolt connection according to the requirements of the drawing.
The bottom of the steel arch frame is arranged on a solid foundation, when the bearing capacity of the foundation cannot meet the requirement, foundation hardening is needed, and broken stones or concrete are laid for hardening so as to ensure the stability of the steel arch frame.
The steel arch frame is erected to ensure that the steel arch frame is tightly close to the surrounding rock wall, a backing plate is arranged when a large gap exists between the steel arch frame and the surrounding rock, and an A6 type steel bar welding net (20 multiplied by 20cm) is welded between the steel arch frames to prevent the rock from falling.
Waste residues generated by excavating the middle pilot tunnel are transported to a specified piling site by a transport vehicle through a filled sidewalk and an existing village road.
Example two, excavation of IV-level surrounding rock:
and (6) measuring and lofting.
And (4) measuring the position of the advanced hollow grouting anchor rod according to a drawing, wherein the circumferential distance of the steel pipes is 40 cm.
The drilling method is adopted.
The diameter of a drilled hole is 3-5 mm larger than that of the steel pipe, after the hole is formed, gravel in the hole is blown out by high-pressure air, then the hollow grouting guide pipe is hammered or jacked in by a drilling machine, the jacking length is larger than 90% of the length of the steel pipe, and the gravel in the steel pipe is blown out by a high-speed fan.
The IV-level surrounding rock arch part advanced anchor rod is a phi 25 hollow grouting anchor rod, the length of the anchor rod is 3.5m, the tail part of the anchor rod is welded to a steel arch belly part to enhance the common supporting effect, a ring is arranged every 2 pieces, and the anchor rod is longitudinally lapped by 1.38 m. After hole distribution is measured, the rock drill is aligned to the hole position, and holes are drilled according to an external insertion angle of 10-15 degrees by taking a steel frame close to an excavation surface as a fulcrum.
After the hollow grouting anchor rod is installed, the hole opening and peripheral cracks are sealed by using plastic cement, and C25 concrete with the thickness of 10cm is sprayed nearby and on the working surface to prevent the working surface from collapsing.
The orifice valve is screwed on the anchor rod pipe orifice, the grouting pipeline is connected, the grouting pump is used for grouting according to the method that the grout is diluted and then concentrated, the grouting amount is large and then small from bottom to top, and the hole is isolated for grouting when the grout is strung or runs.
Before grouting, a grouting system needs to be operated in a test mode, and before grouting, a test is carried out to determine grouting parameters such as reasonable slurry proportion and grouting pressure; and (4) finishing the standard, mainly controlling the grouting amount, and performing final pressure check.
And (4) effect checking: excavating and checking the penetration and consolidation conditions of the slurry; analyzing and judging according to a pressure/pulp quantity curve; and when the design requirements are not met, the hollow anchor rod is additionally arranged.
The excavation mode is mainly a drilling and blasting method and is assisted by manual pneumatic pick excavation.
According to the actual situation of the surrounding rock, the geology is better, and the circulating footage of the actual excavation of the IV-level surrounding rock is not more than 2.0 m. And (4) performing advanced prediction, wherein the IV-grade surrounding rock soil rock body is of a rubble embedded structure, and when the strength is close to that of the III-grade surrounding rock, performing low-light-level blasting by adopting a drilling and blasting method.
And the hole position of the drilling hole is determined according to the measured central line, the measured waist line and the measured excavation contour line.
The peripheral holes are drilled on the profile line of the section, the deviation of the hole sites of the cut holes and the adjustment range along the profile line is less than 5cm, and the deviation of the hole sites of other blast holes is less than 100 mm; after the blast hole is checked to be qualified, the blast hole can be charged and blasted, and the safe step pitch is ensured during blasting. According to the actual situation of the surrounding rock, the advanced forecasting and monitoring measurement data are combined, and when the surrounding rock is really weak, the excavation mode and the support adjustment can be made after the surrounding rock can be checked with the owners, the design, the supervision and other parties on site.
And (5) carrying out mortar anchor rod support on the hole body system.
The holes of the anchor rod holes are arranged according to the requirements of construction drawings, the drilling positions are arranged in the range of 2.0m above the bottom, the longitudinal and circumferential spacing is 100 multiplied by 100cm, and the hole position deviation is less than 100 mm.
The hole axis direction of the anchor rod hole meets the requirements of construction drawings, and the hole axis direction of the anchor rod of the system is vertical to the excavation surface (a phi 22 early strength mortar anchor rod with the length of 2.5m is adopted, and the material and specification meet the design requirements).
Installing a steel arch frame:
the steel arch frame is made of I14I-steel, and the longitudinal distance is 1.0 m.
And (4) after the steel arch frame is processed in a steel bar field, conveying the steel arch frame to the site, and performing on-site bolt connection according to the requirements of the drawing.
The bottom of the steel arch frame is arranged on a solid foundation, when the bearing capacity of the foundation cannot meet the requirement, foundation hardening is needed, and broken stones or concrete are laid for hardening so as to ensure the stability of the steel arch frame.
The steel arch frame is erected to ensure that the steel arch frame is tightly close to the surrounding rock wall, a backing plate is arranged when a large gap exists between the steel arch frame and the surrounding rock, and an A6 type steel bar welding net (20 multiplied by 20cm) is welded between the steel arch frames to prevent the rock from falling.
Waste slag generated by excavating the middle pilot tunnel is transported to a specified piling place by a transport vehicle by using a filled pavement and an existing village road.
And (3) constructing the intermediate wall:
the construction sequence is as follows: the multi-arch tunnel is constructed from a large mileage end to a small mileage end of the tunnel.
The specific position of the intermediate wall is measured according to the drawing, and ash is sprayed.
For the V-level surrounding rock section, the substrate is further reinforced by a phi 25mm hollow grouting anchor rod.
The length of the anchor rods is 3.5m, and the distance is 100 multiplied by 100 cm.
The protective layers of all the circumferential reinforcing steel bars of the intermediate wall are 6.0cm, the arch foot plates of the primary support steel arch frame of the main tunnel are connected with the embedded steel plates in a welding mode, the height of a welding line is 10mm, and the full welding line is guaranteed without residues.
And (3) blanking the reinforced material in a reinforcing steel bar yard according to the size required by the drawing, conveying the reinforced material to a construction site, and binding the reinforced material on the site.
Firstly, mounting circumferential reinforcing steel bars phi 25 (phi 22 for IV-level surrounding rock) at the position of an intermediate wall, arranging at intervals of 20cm (25 cm for IV-level surrounding rock), binding longitudinal reinforcing steel bars phi 12 after welding stirrups, and arranging at intervals of 20cm and adopting binding wires for connection; and finally welding the tie bar phi 12 steel bars at a distance of 20 cm.
And (3) formwork support: and after the steel bar binding and installation are finished, installing the template.
The mid-partition adopts the platform truck once only to pour to the summit, and the template adopts the big block steel form (bolted connection) of customization.
Before installation, the template is firstly subjected to rust removal, cleaning and mold release agent brushing, and then is installed.
In the assembling process, temporary support is added, the section steel is used as a framework after the assembling is finished, and the templates on the two sides are pulled oppositely by pull rods so as to ensure the firmness of the templates in the concrete pouring process.
And after the trolley is in place, the stability of the trolley is positioned and reinforced by using a middle pilot hole steel frame support, and then concrete pouring is carried out.
The longitudinal length of each working section is not more than 6 m.
The middle partition wall concrete must be tightly propped against the guide hole and is densely backfilled.
So as to ensure the firmness of the template in the concrete pouring process.
And after the trolley is in place, the middle pilot tunnel steel frame is used for supporting, the stability of the lining trolley is positioned and reinforced, and then the C30 concrete is poured.
The longitudinal length of each working section is not more than 6 m.
The middle partition wall concrete must be tightly propped against the guide hole and is densely backfilled.
The duration of vibration at each vibration point in the construction process is 20-30s, and the concrete stops sinking and no air bubbles appear, and the surface of the concrete shows floating slurry.
Pouring lining concrete by using a high-pressure concrete delivery pump to ensure that the concrete at the arch crown part is compact; when concrete is poured, reserving a grouting hole every 5m of the arch top of the intermediate wall, and grouting the non-compact part; when the embedded pipe fittings are manufactured and installed, strictly measuring and setting out, and controlling the elevation and the plane position; and the connection between the embedded pipe fittings is processed.
And (5) watering and maintaining after pouring is finished, wherein the maintaining time is not less than 7 days, so that the strength of the concrete is ensured.
After the intermediate wall is excavated, waste water and slurry in construction are removed, drainage ditches are excavated at arch feet of the intermediate pilot tunnel, water in the tunnel is drained out of the tunnel, and basement surrounding rock is prevented from being soaked by water.
And the two sides of the intermediate wall are backfilled by M10 grouted rubbles, and the masonry adopts a mortar sitting method to ensure the fullness of mortar. The backfill height near the front hole side is 3.5 m; and on the side of the rear tunnel, I-shaped steel of I16 (I14 is used for IV-level surrounding rock support) is firstly adopted for transverse support, backfilling is carried out after support, and the backfilling is carried out until the uppermost temporary transverse steel support.
The contact position of the transverse supporting I-shaped steel of the intermediate wall and the intermediate wall is separated by using a rubber pad, so that the I-shaped steel is prevented from damaging the wall body of the intermediate wall.
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 (10)
1. A pilot tunnel construction method in cross tunnel engineering is characterized by comprising the following steps:
the method comprises the following steps: measuring lofting, and measuring the position of the anchor rod according to a drawing;
step two: drilling, namely drilling by adopting a drilling driving method, blowing sand and stones out of holes after hole forming, and then jacking the grouting pipe into the drilled holes;
step three: grouting, welding the tail of a grouting pipe fitting to the steel arch belly for supporting, plugging an orifice and peripheral cracks by using plastic cement after installation, and spraying C25 concrete with the thickness of 15cm near the small guide pipe and on the working surface to prevent the working surface from collapsing;
step four: after the pilot tunnel is excavated, performing surface reinforcement on the primary sprayed concrete on the inner wall of the pilot tunnel to avoid collapse and soil falling;
step five: supporting a mortar anchor rod, wherein the hole of an anchor rod hole is arranged according to the requirement of construction drawing, and the drilling position is arranged in the range of 2.0m above the bottom;
step six: mounting the steel arch after hanging the net on the inner wall of the pilot tunnel, and spraying concrete again after the steel arch is mounted;
step seven: and (6) removing slag.
2. The pilot tunnel construction method in a cross tunnel engineering according to claim 1, characterized in that the grouting pipe fitting of the arch part of the surrounding rock of the V grade is a small guide pipe, a grouting hole with the diameter of phi 8mm is drilled on the pipe body of the steel pipe, the external insertion angle is 10 degrees to 15 degrees, and the tail part is welded on the abdomen part of the steel arch to enhance the common supporting function; setting a ring every 4 trusses, wherein the lapping length of the pipes is 1.46 m; after hole distribution is measured, the rock drill is aligned to the hole position, and holes are drilled according to an external insertion angle of 10-15 degrees by taking a steel frame close to an excavation surface as a fulcrum.
3. The pilot tunnel construction method in a cross tunnel project according to claim 2, characterized in that the pilot tunnel excavation method is mainly artificial pick excavation and assisted by drilling and blasting; the excavation also adopts an upper step excavation method and a lower step excavation method, and the excavation mode of the pilot tunnel can be adjusted according to the monitoring measurement data.
4. The pilot tunnel construction method in a cross tunnel project according to claim 1, wherein the grouting pipe fitting of the IV-level surrounding rock arch is a phi 25 hollow grouting anchor rod, the length of the grouting anchor rod is 3.5m, the tail part of the grouting pipe fitting is welded to the steel arch belly part to enhance the common supporting function, a ring is arranged every 2 pieces of the grouting pipe fitting, and the grouting pipe fitting is longitudinally lapped by 1.38 m; after hole distribution is measured, the rock drill is aligned to the hole position, and holes are drilled according to an external insertion angle of 10-15 degrees by taking a steel frame close to an excavation surface as a fulcrum.
5. The pilot tunnel construction method in cross tunnel engineering according to claim 4, characterized in that the excavation mode is mainly drilling and blasting method and is assisted by manual pneumatic pick excavation; according to the actual surrounding rock conditions, the geology is better, and the circulating footage of the actual excavation of the IV-level surrounding rock is not more than 2.0 m; carrying out low-light-level blasting by adopting a drilling and blasting method; the hole position of the drilling hole is determined according to the measured central line, the measured waist line and the measured excavation contour line; the peripheral holes are drilled on the profile line of the section, the deviation of the hole sites of the cut holes and the adjustment range along the profile line is less than 5cm, and the deviation of the hole sites of other blast holes is less than 100 mm.
6. The pilot tunnel construction method in a cross tunnel project according to claim 1, characterized in that the bottom of the steel arch is erected on a solid foundation, when the bearing capacity of the foundation does not meet the requirement, foundation hardening, paving broken stones or concrete hardening are required to ensure the stability of the steel arch; the steel arch frame is erected to ensure that the steel arch frame is close to the surrounding rock wall, a backing plate is arranged when a large gap exists between the steel arch frame and the surrounding rock, and an A6 type steel bar welding net is welded between the steel arch frames to prevent the rock from falling.
7. The method for constructing a pilot tunnel in a cross tunnel project according to any one of claims 1 to 6, further comprising an intermediate wall construction, wherein the intermediate wall construction comprises the steps of: the method comprises the following steps: measuring, namely measuring the position of the intermediate wall according to a drawing; step two: reinforcing the foundation of the grouting pipe fitting; step three: binding steel bars; step four: erecting a formwork, and installing a formwork after the binding and installation of the steel bars are finished; step five: pouring, namely pouring by adopting concrete; step six: vibrating and maintaining.
8. The pilot tunnel construction method in a cross tunnel project according to claim 7, characterized in that the protective layer of all circumferential reinforcing steel bars of the intermediate wall is 6.0cm, the toe plates of the primary support steel arch frames of the main tunnel are connected with the embedded steel plates in a welding mode, and the height of welding lines is 10 mm; firstly, mounting circumferential reinforcing steel bars phi 25 at the position of the intermediate wall, arranging at intervals of 20cm, binding longitudinal reinforcing steel bars phi 12 after welding the stirrups, and arranging at intervals of 20cm and adopting binding wires for connection; and finally welding the tie bar phi 12 steel bars at a distance of 20 cm.
9. The pilot tunnel construction method in a cross tunnel project according to claim 7, characterized in that the intermediate wall is cast to the top by a trolley at one time, and the formwork is a large block of customized steel formwork; before installation, the template is subjected to rust removal, cleaning and mold release agent brushing, and then installation is carried out; in the assembling process, temporary support is carried out, section steel is used as a framework after the assembly, and the templates on two sides are oppositely pulled by pull rods so as to ensure the firmness of the templates in the concrete pouring process; after the trolley is in place, the stability of the trolley is positioned and reinforced by using a middle pilot tunnel steel frame support, and then concrete pouring is carried out; the longitudinal length of each operation section is not more than 6 m; the middle partition wall concrete must be tightly propped against the guide hole and is densely backfilled.
10. The pilot tunnel construction method in a cross tunnel project according to claim 7, characterized in that the duration of vibration at each vibration point in the construction process is 20-30s, and the degree is that the concrete stops sinking and no bubble appears, and the surface presents floating slurry; pouring lining concrete by using a high-pressure concrete delivery pump to ensure that the concrete at the arch crown part is compact; when concrete is poured, reserving a grouting hole every 5m of the arch top of the intermediate wall, and grouting the non-compact part; when the embedded pipe fittings are manufactured and installed, the paying-off is strictly measured, and the elevation and the plane position are controlled; and the connection between the embedded pipe fittings is processed.
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| CN115573738A (en) * | 2022-09-20 | 2023-01-06 | 保利长大工程有限公司 | Construction process for guiding and entering tunnel in tunnel outlet |
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| CN115573738A (en) * | 2022-09-20 | 2023-01-06 | 保利长大工程有限公司 | Construction process for guiding and entering tunnel in tunnel outlet |
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