CN108798684B - A kind of method of completely decomposed fine sand stratum tunnel excavation - Google Patents
A kind of method of completely decomposed fine sand stratum tunnel excavation Download PDFInfo
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- 239000004576 sand Substances 0.000 title claims abstract description 88
- 238000009412 basement excavation Methods 0.000 title claims abstract description 65
- 238000000034 method Methods 0.000 title claims abstract description 30
- 239000004567 concrete Substances 0.000 claims abstract description 45
- 230000003014 reinforcing effect Effects 0.000 claims abstract description 24
- 238000010276 construction Methods 0.000 claims abstract description 19
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 16
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 11
- 239000010959 steel Substances 0.000 claims abstract description 11
- 229910052742 iron Inorganic materials 0.000 claims abstract description 8
- 239000002689 soil Substances 0.000 claims description 20
- 239000007921 spray Substances 0.000 claims description 18
- 230000002787 reinforcement Effects 0.000 claims description 9
- 238000007363 ring formation reaction Methods 0.000 claims description 7
- 239000011435 rock Substances 0.000 claims description 6
- 238000013461 design Methods 0.000 claims description 5
- 238000005553 drilling Methods 0.000 claims description 5
- 239000011178 precast concrete Substances 0.000 claims description 5
- 238000003466 welding Methods 0.000 claims description 5
- 239000004568 cement Substances 0.000 claims description 4
- 239000004746 geotextile Substances 0.000 claims description 4
- 230000005540 biological transmission Effects 0.000 claims description 3
- 125000004122 cyclic group Chemical group 0.000 claims description 3
- 238000009434 installation Methods 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 2
- 210000003205 muscle Anatomy 0.000 claims 1
- 239000011505 plaster Substances 0.000 claims 1
- 238000009424 underpinning Methods 0.000 abstract description 4
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- 238000001556 precipitation Methods 0.000 description 3
- 241000700608 Sagitta Species 0.000 description 2
- 230000015271 coagulation Effects 0.000 description 2
- 238000005345 coagulation Methods 0.000 description 2
- 239000011440 grout Substances 0.000 description 2
- 230000005641 tunneling Effects 0.000 description 2
- 102000002322 Egg Proteins Human genes 0.000 description 1
- 108010000912 Egg Proteins Proteins 0.000 description 1
- 239000011083 cement mortar Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
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Classifications
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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
- E21D9/04—Driving tunnels or galleries through loose materials; Apparatus therefor not otherwise provided for
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D29/00—Independent underground or underwater structures; Retaining walls
- E02D29/045—Underground structures, e.g. tunnels or galleries, built in the open air or by methods involving disturbance of the ground surface all along the location line; Methods of making them
-
- 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
-
- 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
-
- 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
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/14—Layout of tunnels or galleries; Constructional features of tunnels or galleries, not otherwise provided for, e.g. portals, day-light attenuation at tunnel openings
-
- 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
- E21F16/00—Drainage
- E21F16/02—Drainage of tunnels
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- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
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Abstract
The invention discloses a kind of methods of completely decomposed fine sand stratum tunnel excavation, the relative stability that the method for completely decomposed fine sand stratum tunnel excavation of the invention utilizes fine sand stratum itself to have, the split support for digging range fine sand stratum of reinforcing bar frame is completed using a underpinning technique, balance before fine sand stratum being kept to excavate not excavated and broken under by frame by fine sand, when reaching excavation, disturbance or few disturbance are not generated to the stratum of reservation；Using second underpinning technology, fulcrum is arranged to connect fashioned iron and the Combination beam of steel and concrete of bracing members, completes side and roof arch bracing members with inverted arch bracing members into ring seal；A kind of method of the completely decomposed fine sand stratum tunnel excavation for the safety problem that the solution shallow tunnel of fine sand stratum coating buried depth is constructed in rainy season into hole safety and side slope is provided it is an object of the invention to overcome present in existing fine sand stratum tunnel excavation method the disadvantage that easily landslide, difficulty of construction are high.
Description
Technical field
The invention belongs to Tunnel Engineering field more particularly to a kind of methods of completely decomposed fine sand stratum tunnel excavation.
Background technique
Loose structure formation cementation is weak, and stability is poor, easily collapses in construction.Tunnel passes through this kind of stratum
When, the disturbance to country rock (soil) need to be reduced, generally takes first to protect and dig afterwards, closed support, the closed construction principle when digging, necessity
Shi Caiyong pre-grouting improves the measures such as stratum and control underground water.Fine sand stratum cavitation there are the problem of and risk:
1. tunnel import side slope stable problem is prominent, when tunnel tunnel-face side slope is excavated by design 1:1.5 (vertical: horizontal),
Slump phenomenon is generated because fine sand grain internal friction and natural angle of repose are too small, corresponding position is not proposed into hole to tunnel because designing
Therefore reason measure need to increase open cut tunnel section combination advance support to Tunnel slope supporting and retaining system, when preventing tunnel import from excavating, side slope is collapsed
Collapsing influences tunnel into hole safety.
2. being the loose problem on stratum first, containing certain clay particle in fine sand layer in fine sand stratum tunnel excavation
Though have certain consolidation, excavation face exposure duration be not easy it is too long, once Wall Rock of Tunnel (soil) fine sand layer generate loosen,
Its wall caving effect occurs, and crossing senior general because of sand pressure at the top of bracing members makes the bracing members installed after cavern excavation be deformed or break
It is bad, so as to cause landslide.If loosely caused wall caving effect occurs before bracing members or frame are set up sand, Tunnel Collapse
It will be difficult to control, or even roof fall can be caused exceedingly high, and generate ground pitfall.
3. the problem of fine sand stratum tunnel excavation Second Problem is water, certain glue is contained because of it in slightly wet fine sand stratum
Grain has opposite self-stable ability, before enclosing the loose circle of soil and being formed, spray shield 3-5cm thickness concrete is taken to can achieve newly in time
The purpose of method difficult to understand, i.e., stablized using its own plus spray shield concrete adds bracing members to reach relative equilibrium.But moist fine sand stratum,
Because water content is larger in stratum, stratum is without self-stable ability, once excavation face exposes, it is necessary to and closing measure is taken in time, prevents steel
Branch support, which is enclosed soil and loosened, to cause to cave in.
4. it is external scientific investigations showed that: when fine sand stratum includes clay amount greater than 8%, cannot reach pre- using cement grout
Phase containing consolidated sand effect；Clay content is up to 12% or more in this engineering fine sand, therefore, cement grout containing consolidated sand scheme is taken to be denied.
And ihrigising is taken to reinforce sand foundation or other chemical grouting modes, construction cost is high, and effect is also difficult to ensure.
5. taking deep-well precipitation scheme on ground, well depth depth capacity needs to occupy up to 40m though difficulty of construction is little
The hillside fields of resident industrial crops, it is not only at high cost, and also Cheng Jinghou requires that suitable close purpose filtering material is selected to meet well casing mistake
Water requirement, prevents stratum medium-fine sand particle to be lost again.If when precipitation pump drainage, fine grained is carried out in draining, not only stratum
In fine grain loss will increase ground settlement, and surge shaft and surge shaft march into the arena road may therefore settle, initiation of cracking
Safety problem.
6. Application of light well point precipitation scheme in tunnel is taken, first is that light well point lag face arrangement, to excavation face
Improvement it is limited, second is that with face excavate follow-up construction light well point, increase working procedure so that excavate circulation time add
It is long, seriously affect construction speed.Tunnel section size is smaller, can also cause the inconvenience of Construction Arrangement.
7. add the inverted arch of 0.5m sagitta in excavated section 4.8m*4.8m(gateway opening) tunnel in arrange daguanpeng construction,
It is not only at high cost, but also because fine sand is aqueous, it is still desirable to closing early could effectively.If mixed using spray again after excavation face exposure
Solidifying soil realizes that the effect of New Austrian Tunneling Method, the advantage of steel tube shed will not exist, and construction cost increases instead.
Summary of the invention
It is an object of the invention to overcome easily to cave in, construct present in above-mentioned existing fine sand stratum tunnel excavation method
Difficulty high disadvantage and a kind of solution shallow tunnel of fine sand stratum coating buried depth is provided and is constructed in rainy season into hole safety and side slope
The method of the completely decomposed fine sand stratum tunnel excavation of safety problem.
To achieve the goals above, the present invention adopts the following technical scheme that: a kind of completely decomposed fine sand stratum tunnel excavation
Method, this method comprises the following steps:
Step 1: on fine sand stratum into before hole, the reinforcing bar of two rows of diameter of phi 25~32 is first squeezed into other than tunnel contour line,
10~20cm of bar spacing is close to slope surface and pours tunnel open cut tunnel section, the tail end of two placing of reinforcements poured into open cut tunnel section, open cut tunnel Duan Jing
Empty size is identical as tunnel excavation cross dimensions, and open cut tunnel abutment wall, crown concrete thickness are 40~60cm, open cut tunnel section floor length
For 3~5m, side and roof arch position is shored closely connected with fine sand side slope；
Step 2: arranging one of intercepting ditch at 3~5m other than the above slope excavating sideline of hole face, smeared using cement mortar
Face, and longitudinal drainage ditch is set and is connected to the gutter that hole road side is arranged, prevent slope surface rainwater catchment from causing to rush to hole
Brush；
Step 3: taking reinforced mesh to add spray shield coagulation in the side slope face more than the open cut tunnel floor elevation at open cut tunnel hole excavated
Native supporting, and arrange anchor pole fixed steel bars mesh sheet, anchor pole gos deep into 2~3m of fine sand stratum；
Step 4: open arch hole section concrete intensity reaches 75% or more, tunnel portal excavation is carried out, in tunnel top and open cut tunnel
Junction sets up the first Pin bracing members, and bracing members bottom sets concrete prefabricated cushion block and increases bracing members power transmission connecing to fine sand stratum
Contacting surface product is sunk after control bracing members carrying；
Step 5: within the scope of the bracing members arch portion 180 degree of installation, squeezing into 25~32 reinforcing bar of Φ of length 3.5m, reinforcing bar
Spacing is controlled by 10-20cm, and reinforcing bar tail portion welds together with bracing members, forms the reinforcing bar frame with overhanging ability；
Step 6: slotting excavation is carried out in the middle and upper part of tunnel using excavation equipment, excavation cyclic advance is 0.5-1.0m,
Tunnel floor center retains 2.0m~3.0m high fine sand Core Soil, sand, for stablizing face, and after preventing bracing members stress
Generate ground swell phenomenon；
Step 7: when mechanical excavation is away from design profile 30~50cm of line, being cooperated using artificial chamfered edge；
Step 8: bracing members being installed by spacing 50cm, pass through connection reinforcement welding between bracing members, in the side of bracing members
Reinforced mesh is installed in direction, and reinforced mesh and bracing members, to connect reinforcement welding secured；
Step 9: the secondary concrete that fills spray integrally covers bracing members, completes the primary of bracing members vault and bracing members side wall
Liner supporting work；
Step 10: tunnel excavation gateway opening shape remaining core soil in advance, sand；
Step 11: drainage hole is bored on the concrete of spray shield, it will be in the drainpipe embedment drainage hole using geotextiles sealing；
Step 12: repeating 5-11 step, after 6~8 Pin bracing members are installed, bracing members bottom is excavated to precast concrete pad
At the top of block, fashioned iron together and Combination beam of steel and concrete are poured using bracing members dowel and bracing members, in the side of combination beam
Side wall barricade is set, and gutter is arranged in beams of concrete face between bracing members side wall and side wall barricade, convenient for by the row that catchments in hole
It appears outer；
Step 13: after 50~60m of tunnel drilling depth, tunnel excavation lower part inverted arch position；In fashioned iron and reinforced concrete combination
Beam entirety lower part sets fulcrum, and the cyclization and spray shield concrete enclosing of crown bracing members and inverted arch bracing members are completed by Pin；
Step 14: road surface is formed completing the closed position backfill ballast aggregate of bracing members cyclization, continues the excavation of next hole section,
Until completing fine sand location tunnel excavation and once lining supporting construction.
When top kerf is excavated to apart from 30~50cm of frame, manually formed smooth with spade along excavation contour line chamfered edge
Smooth vault excavation face.
Gutter is arranged in concrete combination beam beam face, is discharged catchmenting in hole outside hole, and side wall is arranged in the outside in gutter
Barricade.
After the completion of remaining core soil in advance position side and roof arch excavates, spray is used to the country rock surface for excavating exposure outside tunnel Core Soil
Concrete enclosing, on moist fine sand stratum with chamfered edge in time by precast concrete backboard bracing members dowel fixed closed,
Prevent fine sand wall caving from sliding, plain 3~5cm of pneumatically placed concrete is thick.
The good effect that above-mentioned technical proposal of the invention generates is as follows: completely decomposed fine sand stratum tunnel excavation of the invention
Method utilize the relative stability that has of fine sand stratum itself, the split digging range of reinforcing bar frame is completed using a underpinning technique
Fine sand is not excavated and is broken under by frame for the support on fine sand stratum, i.e. balance before the excavation of holding fine sand stratum, that is, reaches out
When digging, disturbance or few disturbance are not generated to the stratum of reservation.Using second underpinning technology, to connect the fashioned iron and reinforcing bar of bracing members
Concrete combination beam arranges fulcrum, completes side and roof arch bracing members with inverted arch bracing members into ring seal；Arrangement and method for construction of the invention
Fine sand stratum is not disturbed in ensuring to construct, and is had using the internal friction and movement angle of repose of fine sand stratum internal structure certainly steady
Ability and the common stress of supporting system keep the stabilization and balance on stratum, by the way that tunnel excavation is reduced or avoided to reservation stratum
Disturbance achievees the purpose that New Austrian Tunneling Method " egg shell packet egg " to close early.In Specific construction, using technical solution of the present invention
Fine sand stratum tunnel excavation drilling depth is moved forward steadily according to the 45m/ month, and cave in accident together does not occur, and fine sand stratum tunnel construction takes
Obtained good technical economic benefit.
After completing once lining supporting, drainage hole is arranged on the concrete surface of supporting, gos deep into fine sand stratum 0.2-
0.5m introduces the water in fine sand stratum in tunnel, reduces the soil pressure load outside supporting concrete.
Detailed description of the invention
Fig. 1 is fine sand stratum tunnel excavation import open cut tunnel supporting schematic diagram of the present invention.
Fig. 2 is the schematic diagram that face of the present invention excavates.
Fig. 3 is the cut-away illustration of bracing members of the present invention, combination beam.
Fig. 4 is drainage hole distribution schematic diagram of the present invention.
Fig. 5 is that the present invention excavates inverted arch cyclization rear end structure schematic diagram.
It is marked in figure are as follows: 1, bracing members；2, reinforcing bar frame；3, reinforced mesh；4, concrete prefabricated cushion block；5, open cut tunnel hole
Mouthful；6, combination beam；7, inverted arch bracing members；8, bracing members connect reinforcing bar；9, side wall barricade；10, gutter；11, bracing members side wall；
12, drainage hole；13, drainpipe；14, geotextiles；15, intercepting ditch；16, slope excavating sideline；17, open cut tunnel crown；18, open cut tunnel bottom
Plate.
Specific embodiment
With reference to the accompanying drawing and specific embodiment is to the technical side of the method for completely decomposed fine sand of the present invention stratum tunnel excavation
Case is further elaborated and illustrates.
A kind of method of completely decomposed fine sand stratum tunnel excavation, this method use is in Baoshan, Yunnan Supa River basin Wu Nihe
Power station water diversion tunnel project penstock horizontal segment is located in the horizontal tunnel after surge shaft, and tunnel is across fineness modulus
Thin silt between 1.2 ~ 1.6, fine sand are light yellow, yellow；Tunnel exports the hole 8-10m section stratum for slightly wet fine sand
Layer, it is moist fine sand stratum that the nearly slope buried depth of tunnel, which is greater than 10m, fine sand density of earth formations be in it is close/closely knit, chiltern is impure, contains more
Clay or platelets (thickness about 10cm), part are mutual stratiform, and sorting is good, and particle is uniform；Hand rubbing, which occasionally has, sticks together sense；Rock core
In bulk, local pie.The wide * high of tunnel excavation section=4.8m*4.8m(gateway opening adds the inverted arch of 0.5m sagitta), design is primary
Lining cutting protects concrete, spray shield concrete thickness using the spray of linked network (bar diameter Φ 6.5mm, grid spacing 10cm*10cm)
15cm, secondary lining use armored concrete, lining thickness 0.6m.
As shown in Figure 1, 2, 3, the step of this method is constructed is as follows:
Step 1. on fine sand stratum into before hole, first squeezing into two rows of length 3.5m other than tunnel contour line, diameter of phi 25~
Then 32mm reinforcing bar, 10~20cm of bar spacing, array pitch 40cm are close to slope surface and pour tunnel open cut tunnel Duan Cheng, by two placing of reinforcements
Tail end pours into open cut tunnel section；Open cut tunnel section headroom size is identical as tunnel excavation cross dimensions, open cut tunnel abutment wall, 17 coagulation of open cut tunnel crown
Soil thickness is controlled by 40~60cm；Open cut tunnel section floor length controls 3~5m, side and roof arch position shored with fine sand side slope it is closely connected, it is anti-
When only excavating slope surface inclined-plane in open cut tunnel, slope surface slump；
Step 2. arranges one of intercepting ditch 15 at 3~5m other than the above slope excavating sideline 16 of hole face, using cement bonded sand
Slurry plastering, and longitudinal drainage ditch is set and is connected to the gutter that hole road side is arranged, prevent slope surface rainwater catchment from making to hole
At washing away；
Step 3. takes reinforced mesh 3 plus spray shield mixed the side slope more than 18 elevation of open cut tunnel bottom plate at open cut tunnel hole 5 excavated
Solidifying soil supporting, and arrange anchor pole fixed steel bars mesh sheet, anchor pole gos deep into 2~3m of fine sand stratum；
After step 4. open arch concrete strength reaches 75%, tunnel portal excavation is carried out, on hole top and open cut tunnel junction frame
If the first Pin crown bracing members 1(hereinafter referred to as bracing members), bracing members bottom sets the concrete prefabricated pad of 20cm*20cm thickness 12cm
Block 4 increases the contact area of bracing members power transmission to fine sand stratum, sinks after control bracing members carrying；
Step 5. 180 degree range at the top of the bracing members of installation squeezes into Φ 25~32mm reinforcing bar of length 3.5m, between formation
Away from the reinforcing bar frame 2 for 10~20cm, reinforcing bar tail portion welds together with bracing members, forms the reinforcement shed with overhanging ability
Frame；Power is forced to do one's bidding using what reinforcing bar squeezed into reinforcing bar rod piece and fine sand engaging portion behind fine sand stratum, is made containing the hardened fine sand of clay not
Wall caving is generated to slide；Second, the formation using reinforcing bar frame overhangs ability, when preventing excavation face from slump occur, frame
The slump of overhanging ability prevention top fine sand；
Step 6: slotting excavation being carried out in the middle and upper part of tunnel using excavation equipment, cyclic advance is excavated and is controlled by 0.5-1.0m
System, tunnel floor center retains 2.0m~3.0m high fine sand Core Soil, for stablizing face, and after preventing bracing members stress
Generate ground swell phenomenon；
Step 7: when mechanical excavation is away from design profile 30~50cm of line, smooth smooth arch being cooperatively formed using artificial chamfered edge
Push up excavation face;After the completion of remaining core soil in advance position side and roof arch excavates, to country rock (soil) surface for excavating exposure outside tunnel Core Soil
It is closed using pneumatically placed concrete, the poor exposure of stability increases concrete prefabricated backboard protection, and plain 3~5cm of pneumatically placed concrete is thick.
Step 8: Pin bracing members being installed by spacing 50cm, and reinforced mesh is installed, reinforced mesh and bracing members, bracing members connect
It is secured to connect reinforcement welding；
Step 9: the secondary concrete that fills spray integrally covers bracing members, and bracing members vault and bracing members side wall 11 are completed once
Liner supporting work；
Step 10: tunnel excavation gateway opening shape remaining core soil in advance (sand);
Step 11. bores drainage hole 12 on spray shield concrete, the embedment draining of drainpipe 13 that will be sealed using geotextiles 14
In hole;
Step 12. repeats 5-11 process, and after installing 6-8 Pin bracing members, bracing members bottom is excavated to precast concrete pad
At the top of block, a road width * high=20cm*20cm fashioned iron and reinforcing bar are poured using bracing members connection reinforcing bar 8 and bracing members at the top of cushion block
Concrete combination beam 6 guarantees mounted bracing members composite entity stress, and side wall barricade 9, steel branch is arranged in the side of combination beam
Gutter 10 is arranged in the beams of concrete face supportted between side wall and side wall barricade, is discharged outside hole convenient for will catchment in hole;
After step 13. tunnel drilling depth 50-60m, depending on traffic maintenance cost situation in hole, tunnel excavation lower part inverted arch position,
Fulcrum is set in fashioned iron and reinforced beam entirety lower part appropriate location, completes even crown bracing members and inverted arch bracing members 7 by Pin
Cyclization and spray shield concrete enclosing;
Step 14. completes the closed position backfill ballast aggregate formation road surface of bracing members cyclization, continues to excavate next hole section
It excavates, until completing fine sand location tunnel excavation and once lining supporting construction;
Step 15. clears up inverted arch and backfills ballast aggregate, carries out concrete secondary liner construction.
Construction personnel's strict implement construction requirement guarantees that the bracing members top rebars frame lap of splice is not less than 1.5m, and presses
Above-mentioned steps implement measures, and fine sand stratum tunnel excavation drilling depth, which realizes, to be moved forward steadily the 45m/ month, and tunnel is with passing through fine sand
Enter rock hole section after layer length about 90m, tunnel does not occur cave in accident together when passing through fine sand stratum, creates preferable
Technical economic benefit.
Claims (4)
1. a kind of method of completely decomposed fine sand stratum tunnel excavation, it is characterised in that: this method comprises the following steps:
Step 1: on fine sand stratum into before hole, the reinforcing bar of two rows of 25~32mm of diameter of phi, steel are first squeezed into other than tunnel contour line
Muscle 10~20cm of spacing is close to slope surface and pours tunnel open cut tunnel section, the tail end of two placing of reinforcements poured into open cut tunnel section, open cut tunnel section headroom
Size is identical as tunnel excavation cross dimensions, and open cut tunnel abutment wall, crown concrete thickness are 40~60cm, and open cut tunnel section floor length is
3~5m, side and roof arch position are shored closely connected with fine sand side slope；
Step 2: one of intercepting ditch is arranged at 3~5m other than the above slope excavating sideline of hole face, using cement sand plaster, and
Longitudinal drainage ditch is set and is connected to the gutter that hole road side is arranged, prevents slope surface rainwater catchment from causing to wash away to hole；
Step 3: taking reinforced mesh to add spray shield concrete branch in the side slope face more than the open cut tunnel floor elevation at open cut tunnel hole excavated
Shield, and arrange anchor pole fixed steel bars mesh sheet, anchor pole gos deep into 2~3m of fine sand stratum；
Step 4: open arch hole section concrete intensity reaches 75% or more, carries out tunnel portal excavation, hands on tunnel top and open cut tunnel
It meets place and sets up the first Pin bracing members, bracing members bottom sets concrete prefabricated cushion block and increases the contact of bracing members power transmission to fine sand stratum
Area sinks after control bracing members carrying；
Step 5: within the scope of the bracing members arch portion 180 degree of installation, Φ 25~32mm reinforcing bar of length 3.5m is squeezed into, between reinforcing bar
Away from controlling by 10-20cm, reinforcing bar tail portion welds together with bracing members, forms the reinforcing bar frame with overhanging ability；
Step 6: slotting excavation being carried out in the middle and upper part of tunnel using excavation equipment, excavation cyclic advance is 0.5-1.0m, tunnel
Bottom centre retains 2.0m~3.0m high fine sand Core Soil, sand, generates for stablizing face, and after preventing bracing members stress
Ground swell phenomenon；
Step 7: when mechanical excavation is away from design profile 30~50cm of line, being cooperated using artificial chamfered edge；
Step 8: bracing members being installed by spacing 50cm, pass through connection reinforcement welding between bracing members, in the side directions of bracing members
Reinforced mesh is installed, reinforced mesh and bracing members, to connect reinforcement welding secured；
Step 9: the secondary concrete that fills spray integrally covers bracing members, completes the once lining of bracing members vault and bracing members side wall
Support work；
Step 10: tunnel excavation gateway opening shape remaining core soil in advance, sand；
Step 11: drainage hole is bored on the concrete of spray shield, it will be in the drainpipe embedment drainage hole using geotextiles sealing；
Step 12: repeating 5-11 step, after 6~8 Pin bracing members are installed, bracing members bottom is excavated to precast concrete cushion block top
Portion pours fashioned iron together and Combination beam of steel and concrete using bracing members dowel and bracing members, is arranged in the side of combination beam
Side wall barricade, the beams of concrete face between bracing members side wall and side wall barricade arranging gutter, hole are discharged convenient for will catchment in hole
Outside；
Step 13: after 50~60m of tunnel drilling depth, tunnel excavation lower part inverted arch position；It is whole with Combination beam of steel and concrete in fashioned iron
Body lower part sets fulcrum, and the cyclization and spray shield concrete enclosing of crown bracing members and inverted arch bracing members are completed by Pin；
Step 14: road surface is formed completing the closed position backfill ballast aggregate of bracing members cyclization, continues the excavation of next hole section, until
Complete fine sand location tunnel excavation and once lining supporting construction.
2. a kind of method of completely decomposed fine sand stratum according to claim 1 tunnel excavation, it is characterised in that: top kerf
When being excavated to apart from 30~50cm of frame, smooth smooth vault excavation face manually is formed along excavation contour line chamfered edge with spade.
3. a kind of method of completely decomposed fine sand stratum according to claim 1 tunnel excavation, it is characterised in that: in concrete
Gutter is arranged in combination beam beam face, is discharged catchmenting in hole outside hole, and side wall barricade is arranged in the outside in gutter.
4. a kind of method of completely decomposed fine sand stratum according to claim 1 tunnel excavation, it is characterised in that: reserved core
After the completion of native position side and roof arch excavates, the country rock surface that exposure is excavated outside tunnel Core Soil is closed using pneumatically placed concrete, in tide
Wet fine sand stratum, in time by precast concrete backboard bracing members dowel fixed closed, prevents fine sand wall caving sliding with chamfered edge
It falls, plain 3~5cm of pneumatically placed concrete is thick.
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| CN110030004B (en) * | 2019-05-29 | 2024-01-23 | 东华理工大学 | Method for excavating barrier lake drainage tunnel |
| CN110344855A (en) * | 2019-06-27 | 2019-10-18 | 中国电建集团西北勘测设计研究院有限公司 | The supporting construction of diversion tunnel under a kind of large ground pressure |
| CN110552723B (en) * | 2019-09-16 | 2021-01-26 | 中国十九冶集团有限公司 | Treatment construction method for continuous collapse roof fall of small-section steep slope tunnel |
| CN110940571B (en) * | 2019-12-09 | 2023-02-17 | 河北建筑工程学院 | Test device for simulating dynamic soil arch effect of shed frame structure |
| CN111735931A (en) * | 2020-05-28 | 2020-10-02 | 北京市政建设集团有限责任公司 | Experimental device and method for stability of tunnel face with different water content fine sand structures |
| CN112031813B (en) * | 2020-09-08 | 2022-09-13 | 中交一公局第一工程有限公司 | Construction method for penetrating through clay loose tunnel collapsed body |
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