Left line roofing construction program
Yangqu No.1 Tunnel left inlet ZK93+907 ~ ZK93+917 section is located in the biased section, and the section of loess with high water content, tested loess water content of 19.2~21%. And also encountered the spring thawing period, resulting in the soil itself strength greatly weakened, resulting in the soil self-stability is extremely poor, resulting in the left line into the hole roof soil instability, and caused the arch subsidence, the Department immediately take remedial measures, the bias pressure section unloading treatment, due to the left line into the hole when the left side of the overburden layer is only less than 1m, so in the unloading process will be the left line of the right side of the arch roof of the soil unloaded almost with the left side of the perimeter of the rock basically, resulting in the weak cover of the hole, the top of the section is weak. As a result, the cover layer of the roof was weak, and at 7:00 a.m. on April 1, 2010, without any construction work on the palm face, the left line was toppled (ZK93+907～ZK93+917) On April 1, 2010, the mileage section of the left line of the Yangqu No. 1 Tunnel, ZK93+907～ZK93+917, was toppled in the process of manual unloading at the roof of the tunnel.
Tunnel left line ZK93+907 ~ ZK93+917 mileage section, the height and width of the landslide are large, and the collapse of the loose body, the basic idea of dealing with the open excavation and then support approach, first remove the collapse of the soil, then slope repair, followed by initial support, to be the second lining construction for the arch top backfill. A construction method
1, collapse body cleanup and slope excavation protection (1), slope construction process:
Measurement and sampling, set up slope isolation zone, construction of the top of the slope temporary water cut-off gutter, excavation of the slope, set up a high slope monitoring and measuring points to clean up the ballast for the construction of the back of the supply
(2), the construction method:
Road graben slope: excavation slope rate of 1:0.5, when the slope height is less than or equal to the slope height of the slope is less than or equal to the slope height of the slope, the slope rate of 1:0.5, when the slope height is less than or equal to the slope height of the slope, the slope rate of 1:0.5. When the slope height is less than or equal to 10 meters, no platform, a slope to the top; when the slope height is greater than 10 meters less than or equal to 32 meters, every 8 meters high to set up a 2-meter wide platform. The foot of the arch is widened by 0.5 meters at each outer side. Details see the left
line open cut section map.
After all the excavation of the slope, the construction of the elevation supply, in strict accordance with the method of excavation of the open hole construction, and do a good job of the tunnel steel arch support, to ensure that the top of the hole backfill after the tunnel is formed after the safe operation. 2, initial support (1), the construction process:
Slope excavation Measurement and sampling set up steel arch Hanging plate spray concrete support.
(2), construction methods:
①, set up the frame: slope excavation in place, after measurement and sampling, before setting up the frame construction
work, the foot of the pad concrete prefabricated blocks or steel plate, prohibit the foot of the arch to backfill the loose soil or the foot of the arch overhanging; steel arch frame after installation of the foot of each 45 ° diagonally downward to play 2 locking anchor (φ25 threaded steel), the length of the L = 4.5 meters.
②, spray concrete support using hanging φ8 double-layer mesh spray anchor support, spray concrete construction using
in the steel arch hanging template method of construction and maintenance, spray anchor process, pay attention to the foot of the arch should be sprayed filled with dense, the foot of the outer 0.5 meters of the range of backfill with shotcrete.
③, the construction process should be high slope monitoring measurement, timely feedback monitoring information,
for the correct use, modify the excavation and support parameters to provide a basis for ensuring construction safety and construction quality.
3, roof backfill
After the second lining of the tunnel should be backfilled in the excavation part in a timely manner, and the high slope is not
exposed for a long time to ensure the safety and stability of the slope.
Backfilling should be carried out after the concrete strength of the secondary lining reaches the design strength, and the back of the wall at the foot of the arch is backfilled with slurry masonry; and then backfilled with compacted soil in layers, backfilling must be symmetrical backfilling on both sides of the arch wall
and compacted with small equipment, the thickness of each layer is not more than 0.3M, and the difference in height between the two sides of the backfilled surface shall not be more than 0.5M. Backfilled to flush with the arch, and then filled in layers to the design of the arch, the backfilling should be carried out in layers to the design of the arch wall. Backfill to flush with the top of the arch, and then layered full fill to the design height. When mechanical backfill is used, it should be carried out after the artificial or small-sized machinery tamping and filling more than 1.0M above the top of the arch; the top layer of backfill adopts 50cm clay layer and 50cm planting soil backfill. When backfilling the clay waterproof layer, the waterproof layer should be well connected with the ground surface and closed tightly to prevent the surface water from infiltrating and affecting the stability of the backfilled body. Second, the next tunnel into the hole program
In the completion of the above landslide section of the treatment should be timely to create a favorable working surface, early into the hole construction. In order to prevent the big deformation and collapse problem of tunnel excavation in loess, the tunnel adopts double side-wall guide pit method after entering into the tunnel, combining with spray concrete to close the excavation surface in time, using small conduit support, steel support, hanging net, anchor to strengthen the strength of soil and limit the redistribution of the surrounding rock stress, and implement the short excavation and fast circulation to reduce the disturbance of soil. In order to be able to safely enter the hole, into the dark hole before the use of 4m long double rows of small conduit overrun support, double sidewall guide pit method of excavation, and the use of I22b steel frame (longitudinal spacing of 50cm) as the initial support to enter the hole smoothly, the hole into the program is described in detail as follows:
To the collapsed section of the initial support construction is completed, do a good job of the roof of the cave anti-drainage, in the opening line of the outside of the 5m to make the interceptor gutter, the rain will be led to the original gutter on both sides of the tunnel. Lead to the original ditch on both sides of the tunnel, water intercepting gutter using turf gutter, detailed drawings are as follows:
Cave roof water intercepting ditch
(turf gutter)
1, double small conduit construction
After the last collapsed section of the body by the palm face arch frame is set up, in the arch frame of the top and bottom of the rows of over the front of the small catheter, on-site processing of small catheter, spray concrete closed rock face, rock drill drilling and shotcrete closed rock face, rock drill and the small catheter, the small catheter is used as a guide for the construction of the tunnel.
Over-the-horizon small conduit construction process flow chart
Over-the-horizon small conduit for the outer diameter of φ42mm × 4mm steel flower pipe, the pipe wall around the 15cm spacing according to the plum blossom shape, drilling φ6mm grouting holes, the drilling angle, depth, density and slurry ratio in line with the design requirements, the grouting pressure is in line with the specification requirements. Two rows of small conduit were adjacent to the excavation
face of the top and belly of the steel frame for the fulcrum, after the injection of steel pipe grouting, the formation of pipe grill support ring, small conduit grouting using cement slurry (add cement weight 5% of water glass), water-cement ratio of 1:1; the concentration of water glass for the 35 Boomerang, water glass fineness modulus of 2.4, grouting pressure of initial pressure of 0.5 ~ 1.0MPa, the end of the pressure is 2.0Mpa.
Construction, grouting abnormal treatment: the occurrence of cascading slurry, under the conditions of more than one grouting machine, grouting at the same time, when the grouting machine will be less cascading slurry holes in time to plug, the turn of the pipe grouting, and then unplugging the blockage, with a wire or a fine steel bar will be cleaned up the tube and high-pressure wind or water flushing, and then grouting, the cement and water-glass two-liquid slurry into the slurry is very large, the pressure for a long time does not rise, then the slurry concentration should be adjusted and the mix should be adjusted, and the slurry concentration should be adjusted, and the pressure should be adjusted, and the slurry concentration should be adjusted. Should adjust the slurry concentration and ratio, shorten the gel time, small pump volume low pressure grouting or intermittent grouting, so that the slurry in the fissure has a relative residence time in order to gel, but the residence time can not be more than the gel time of the mixed slurry. 2、Double sidewall guided pit method construction
After the grouting reaches a certain strength, the excavation process starts, the section is in the V
level shallow buried section, the excavation method adopts double sidewall guided pit excavation method. (1) Construction process:
Excavate part of the core soil, and start excavation by double sidewall guide pit method. Left side guide hole over-advance pre-supporting support Excavate left side guide hole Initial support of left side guide hole (erection of steel support and anchor spraying) and side wall Excavate right side guide hole Initial support of right side guide hole (erection of steel support and anchor spraying) and side wall Over-advance pre-supporting support for half of the section Excavate the upper half of the section Initial support of the upper half of the section (erection of steel support and anchor spraying) Excavate the lower half of the section (erection of steel support and anchor spraying) (Anchor spraying) Excavation of the second half of the section Initial support of the second half of the section (erection of steel support and anchor spraying) Removal of the side wall Filling of the back arch concrete to start the next cycle.
(2), the construction method: ①, in the double row of small conduit construction is completed, with the excavator to dig out the palm face and set of arch core soil, leveling out the work platform.
②, because the import section is Va level shallow buried section, so the double sidewall guide pit method of excavation. After excavation of the cave, the initial support (including the arch) and the side of the next wall, so that the cave as soon as possible to form a closed loop. The longitudinal spacing of the side next door wall steel support is the same as that of the initial support steel support of the main cave body, and the side next door wall steel between the adjacent two bays is welded with φ25 steel bars with a ring spacing of 1.0 m to strengthen its integrity, and the next door wall steel support should be welded firmly with the main cave's arch and the support at the superelevation arch, and the construction of the side next door wall steel support is the same as that of the corresponding main cave's steel support construction, especially in the foot of the arch of temporary steel support for support and fixation, with 5.5m pads under the steel arch, and the steel arch is fixed with the steel arch. Especially at the foot of the temporary steel support arch, it is well supported and fixed, with 5cm thick wooden boards or cement prefabricated blocks under the steel arch, and the foot of the arch is reinforced by locking small conduit or temporary elevation supply. Double sidewall guide pit method excavation schematic diagram is as follows:
Excavation sequence of class V perimeter rock:
The following steps of excavation should be carried out in the pre-supporting over-head small conduit and grouting or
large pipe shed pre-support is completed and has reached the intensity of:
1, the left side of the guide hole over the front pre-supporting; 2, excavation of the left side of the guide hole;
half-section
3, Initial support of left side guide hole (erection of steel
support and anchor spray) and
side wall; 4. Over-advance pre-support of right side guide hole; 5. Excavation of the right side guide hole; 6. Initial support of the right side guide hole (erection of steel
support and anchor spray) and side wall; 7. Over-advance pre-
right side guide hole in the upper half-section
φ25 steel bar
Ring spacing 1.0m
Left side guide hole
Lower section
support; 8. Excavate the upper half section; 9. Initial
support of the upper half section (erection of steel support and anchor spraying).10. Excavate the lower half
section; 11. Initial support of the lower half section (erection of steel support
and anchor spraying).12. Demolish the sidewalls. wall.13, filling the back arch
concrete.14, laying ring blind ditch and waterproofing board, the whole
filling the second lining concrete.
Ⅴ enclosure construction process elevation diagram
③ construction step: palm surface and initial support spacing is not greater than 1.1 meters, initial support and second lining spacing is not greater than 35 meters, the left and right palm surface should be crossed.
④Slagging adopts excavator with dump truck slagging. ⑤ Initial spraying concrete
The initial spraying concrete operation is carried out in time after excavation, and the wet sprayer must be used for spraying concrete. Requirements for the initial spraying of concrete before the use of high-pressure duct or high-pressure water pipe will be the rock wall dust, debris rinsed clean, after passing the inspection before spraying operations, the length of each section of the ring should not be more than 3m, the spray material should be placed on the tin, the initial spraying of the concrete layer thickness of 4cm.
～ 1000
～ 500
～ 500
～ 500
～ 500
～500
Secondary lining
Left guide hole
Digging direction
Lower half section upper half section
Right guide hole
V perimeter rock construction process plan
⑥ I-beam (I22b) installation
I-beam steel frame installation in strict accordance with the measuring The longitudinal spacing of the steel frame is 50cm, and the two bays of steel frame are firmly connected with φ22mm steel bars, with the longitudinal joint bars spaced 1m apart, welded on the inner side of the steel frame, and the overlap with the steel frame is firmly welded with double-sided welding, which requires that the weld seam is full, and the welding length is not less than 5 times of the diameter; the I-beam steel frame base must be dropped on a firm foundation, and the base is cleared of floating dregs prior to the installation; the sections between I-beam steel frames use the design drawings specified in the design drawings, which are used for the construction of I-beam steel frames. The I-beam frame is fastened with bolts and nuts of the type specified in the design drawings.
Tunnel center line
φ22 connecting bar
Sample of connecting bar
Note:
1, the dimensions of this drawing are measured in centimeters; 2, this design applies to the Va lining; 3, the steel support consists of I22b I-beam;
V
type lining steel support design drawings
4, unspecified place Refer to "Tunnel Chapter" S5-7-7.
Note: (1) I-beam processing, welding connection is not allowed, do need to be connected, required to use the steel plate connection; 2, the stress components
welding welding rod requires the use of E5003 or more welding rod).
⑦ Anchor
I-beam steel frame set up, in the position of the bottom plate of the steel frame in each bays with electric coal drill manually hit the locking foot anchor hole, after the hole hit the hole with a high-pressure wind will be inside the hole of the rock debris blowing clean, the anchor installation requires the rod body is straight, rust, oil, mud; locking foot anchors D25mm hollow grouting anchors, 4.5m long, in the scissors and I-beam steel frame welded to the edges of the two firm, must ensure that the weld is full, the weld seam is full, the weld seam must be E5003 or more welding rods. Ensure that the weld is full, the weld is double-sided welding, shall not damage the mortar anchor; system radial anchor using φ25 early-strength mortar anchor, ring, longitudinal spacing of 80cm × 50cm, 4.5m long. ⑧ Laying of reinforcing steel mesh
Reinforcing steel mesh using φ8mm steel, double-layer reinforcing steel mesh, grid spacing 20cm × 20cm, reinforcing steel mesh lap length of not less than 30d, before laying Descaling, reinforcing steel mesh in the initial spraying of concrete after hanging, so that it is formed with the concrete as a whole, with the initial spraying of concrete surface undulation laying, and the initial spraying of the surface of the gap is generally not more than 3cm; reinforcing steel mesh should be welded with I-beam arches and the system of anchors firmly
Solid, to ensure that the reinforcing steel mesh does not shake when spraying concrete, if there is a shedding of stone or concrete block by the reinforcing steel mesh stuck in a timely manner to remove, (the reinforcing steel mesh must be made) (Reinforcement mesh production must be welded connections, not allowed to tie connections). ⑨ ahead of the small conduit
implementation, the use of air-legged wind-operated rock drill manually drilling, conduit length of 4.0m, the conduit is inserted into the hole not less than 95% of the depth of the hole, ahead of the small conduit set the longitudinal spacing of 2.5m, the ring spacing of 40cm, the longitudinal length of the two adjacent rings lap length of not less than 1.0m, the permissible deviation from the hole position of ± 50 mm; the hole should be drilled round and straight, the outer interpolation angle of 10 ° ~ 15 °, the mouth section of 120cm, the hole section of 120cm. 15 °, the mouth section of the 120cm range of steel pipe is not open, the rest of the parts in accordance with the 15cm spacing staggered grouting holes, hole diameter of 6mm; over the small conduit support to meet the following requirements: a, over the small conduit and I-beam steel frame with the use of;
b, over the small conduit length and arrangement in line with the design requirements, ring spacing of 40cm; c, over the small conduit outside the foot of 10 ° ~ 15 °, longitudinal conduit lap length of less than 1.0m adjacent to the two rings. 15°, longitudinal conduit lap length shall not be less than 1.0 meters. ⑩ spraying concrete
Spraying concrete in the I-beam arch construction is completed and reported to the site quality inspector, supervisor inspection can only begin operations, spraying thickness of 29cm, must use wet sprayer spraying concrete.
The spraying concrete material must be in line with the requirements of the ratio, the designated manufacturers of qualified products, with sand and gravel after laboratory testing, water quality should be in line with the project water standards. Before spraying concrete, high-pressure water or high-pressure wind will be the initial spray surface of dust and debris rinsing, must be cleaned up the bottom of the arch pumice, to be inspected and qualified before the operation; spraying, such as the discovery of loose blocks of stone or blocking material, should be promptly removed, spraying operations shall not be used to backfill the over-excavation of the slice of stone or wood
spraying materials should be placed on the tin, spraying operations should be segmented, sub-section by section, from the bottom to the top Sequence, the length of each section should not exceed 6m, control the rebound rate, rebound material shall not be reused as jetting material, jetting machine start, should be the first to send air and then boot, and should be sent after the normal operation of the machinery, the material should be supplied uniformly and continuously, the end of the operation, the first to stop sending material to be material tank residual material sprayed and then shut down, then shut down the wind, stop the operation, the jetting machine and the residual material in the delivery pipe should be removed in a timely manner to avoid clumping and clogging. After stopping the operation, the residual material in the jetting machine and the feeding pipe should be removed in time to avoid blockage.
Precautions:
a, the mixture is mixed with the use of dry mix without mixing quick-setting agent storage time is not greater than 2h; mixing quick-setting agent dry mix storage time is not greater than 20min.
b, the mixing amount of quick-setting agent is accurate, add uniformity, shall not be arbitrarily increased or reduced. c, the nozzle should be perpendicular to the rock surface, and at the same time should maintain an appropriate distance and jetting pressure. d, maintenance and protection after spraying, maintenance period prohibited machinery, vehicle collision and man-made damage.
e, the average thickness of shotcrete is not less than the design thickness, the minimum thickness is not less than 1/2 of the design thickness and ≥ 50mm;
? Tunnel excavation and support follow the construction principle of short scaling, and support, early closure, and then enter the next cycle of operation after all the above processes are completed. 3、Monitoring and measurement
Strengthen the over-geological forecast and deformation of the surrounding rock measurement work, timely feedback construction, for the correct use, modification of excavation and support parameters to provide a basis. To ensure construction safety and construction quality. Import section of the cover layer is thin, after excavation, the surrounding rock is difficult to self-stabilize into an arch, the surface is easy to subsidence, in order to ensure the construction safety of the shallow buried section of the cave, the surface settlement monitoring. Layout principle is: in the roof of the ground
section along the tunnel axial every 5 ~ 10m laid. At the same time in the transverse according to the actual situation, selected the main section, along the main section of the deployment of measuring points, in order to understand the lateral impact of surface settlement range. At the same time to do a good job of the vault subsidence and convergence measurement of the periphery, to ensure that the data is true, to guide the construction, the measurement point layout see "surface subsidence measurement measurement point layout".
The monitoring instruments are: precision level, indium steel ruler, convergence meter and so on. Surface Subsidence Measurement Layout Diagram
4, arch, secondary lining
Inlet shallow buried section, secondary lining in the tunnel arch after 15m, arch per construction
length control within 3 meters, arch construction should be followed by the palm face, in order to facilitate the construction of the trestle bridge across the way. Lining using 9m full cross-section whole hydraulic lining cart, concrete mixing by automatic metering mixing station, concrete transport tanker truck transportation, concrete pump pumping into the mold irrigation, secondary lining full cross-section of the one-time application, Class V perimeter rock and palm face distance of not more than 35 meters. Third, the emergency plan
tunnel shallow buried section of the geological situation is poor, in order to ensure the safety of tunnel construction and tunnel palm face behind
after the accident, to ensure the safety of trapped people, fast and effective implementation of the rescue, minimize the loss of the accident, to take the following measures: the tunnel main construction to the pedestrian cross-passage or cross-passage of the vehicle, in a timely manner through the cross-passage for use in the emergency rescue; The ventilation pipe near the palm face is made of 1200×10mm steel pipe, with a length of 100m; the steel pipe is used as an escape route for the trapped personnel when the tunnel collapses;
Wireless telephone is set up in the cave, and UPS-powered lighting is used for construction lighting; food, emergency medical drugs and related equipment are prepared near the palm face; temporary steel frames, timber, drilling rigs, pumping machines and other facilities are prepared outside the cave; facilities such as disaster prevention and rescue drills are carried out at appropriate intervals in the course of the construction. Disaster prevention and rescue drills will be carried out in due course. Safety requirements and measures
? Strengthen the training of technical and construction personnel to improve the safety and quality awareness of all participants.
? Loess tunnel construction in strict accordance with the "first detection, pipe ahead, non-blasting, strict control of water, short footage, strong support, diligent measurement, early lining" principle of organizing construction.
? Strictly in accordance with the excavation method specified in the design documents for construction, or should be in accordance with the change program application to change the construction program.
? Before the tunnel excavation, the scope of the tunnel surface near the center line of the survey, the surface of the gullies, deep wells, landslides, traps, surface attachments and other adverse geological conditions for statistics, and according to the mileage pile number one by one registration, photographs, especially tunnels under the highway and other large structures, the construction of the tunnel should be strengthened to monitor the work of measurement, and strictly in accordance with the design of the construction program, to ensure that the tunnel is safe and smooth passage.
? Measurement and sampling per cycle, strict control of over and under excavation. Regularly check and review the measurement control points to avoid damage to the control points due to subsidence, bulging, uneven deformation and artificial or mechanical
collision under the tunnel.
? The foundation bearing capacity of the side wall, back arch or bottom plate must meet the design requirements. Weak foundation treatment methods and construction quality should meet the design requirements, and construction process design should be carried out before excavation at the bottom of the tunnel.
? After excavation, the perimeter rock measurement should be carried out according to the measurement items and frequency required by the design, and the measurement information should be fed back in time.
? In the tunnel excavation, after each excavation, timely observation and description of the surrounding rock fissure structure, rock hardness and softness, the size of the water discharge, check the design, and judge the stability of the surrounding rock.
? Soil tunnel in the excavation process, minimize the excavator on the edge of the tunnel excavation, should use artificial pickaxe on the tunnel periphery to trim, reduce the disturbance of the surrounding rock, to avoid the side wall or arch falling block phenomenon; arch foot, wall corner should be reserved 30cm artificial excavation, prohibit over-excavation; soil tunnel arch wall foot is strictly prohibited from being soaked with water; after excavation, should be as early as possible on the peripheral rock for the support of the closure, to reduce the exposure of the surrounding rock time.
? Develop a safe construction emergency plan, and do a good job of emergency material reserves on a daily basis. (11) Loess tunnel construction should do a good job of cave roof, cave door and cave anti-drainage system. The cave door and cave drainage ditch should be paved and mortar smeared to prevent surface water and construction water from seeping and affecting structural safety. Stratum water content is large, the upper step near the palm surface should be excavated horizontal ditch, the water will be led to the tunnel in the middle of the longitudinal drainage ditch discharged out of the hole, so as not to soak the arch foot, if necessary, should be with the wells point descending and other measures to reduce the groundwater level to the tunnel below the bottom of the second lining, to ensure that the construction is carried out smoothly.
(12) Road construction work lot must ensure adequate lighting. Insecurity factors are greater than the ground
section should increase the illumination. In the main traffic road, hole pumping station should be set up security lighting, leakage of electricity lot lighting should be used waterproof lamp head and lampshade. V. Environmental protection and civilized construction
? When excavating the dark hole division, under the premise of meeting the design specifications and safety and quality requirements, the construction process suitable for mechanized operation should be adopted as much as possible, the division size is divided reasonably, and the divisions try to work in parallel, so as to achieve the purpose of rapid construction.
? Abandon ballast should be directed by special person, pile neatly, slope leveling, abandon ballast field need to set up retaining wall. The construction process eliminates the arbitrary dumping of the ballast and the dumping of the soil. After the construction is finished, the abandonment of ballast field timely leveling, and do a good job of greening, protection, avoid soil erosion.
? Tunnel in the whole construction process, the operating environment should comply with the following occupational health and safety standards:
A. Oxygen content in the air, by volume shall not be less than 20%;
B. Dust permanent permissible concentration of dust, per cubic meter of air containing more than 10% of free silicon dioxide dust shall not be greater than 2mg, per cubic meter of air containing less than 10% of free silicon dioxide mineral Dust shall not be greater than 4mg;
C. Maximum permissible concentration of hazardous gases:
a Maximum permissible concentration of carbon monoxide is 30mg/m3, under special circumstances, construction workers must enter the work surface, the concentration of 100mg/m3, but the working time shall not be greater than 30min;
b Carbon dioxide by volume shall not be greater than 0.5%; c Nitrogen oxides (converted to nitrogen dioxide) shall not be greater than 2mg. c Nitrogen oxides (converted to NO2) of 5mg/m3 or less; C Temperature in the tunnel shall not be higher than 28°C;
D Noise in the tunnel shall not be greater than 90Db.
? When the length of construction sole head boring exceeds 150m, mechanical ventilation shall be adopted to ensure the supply of 3 m3/min of fresh air per person in the tunnel.
? The right-of-way and the construction site should pay attention to spreading water and dust prevention to reduce the damage to the surrounding environment.
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