CN112253176A - Combined supporting structure system for realizing large-span and small-clear-distance tunnel and construction method thereof - Google Patents
Combined supporting structure system for realizing large-span and small-clear-distance tunnel and construction method thereof Download PDFInfo
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- 238000010276 construction Methods 0.000 title claims abstract description 30
- 238000009412 basement excavation Methods 0.000 claims abstract description 64
- 229910000831 Steel Inorganic materials 0.000 claims description 60
- 239000010959 steel Substances 0.000 claims description 60
- 239000011435 rock Substances 0.000 claims description 38
- 238000000034 method Methods 0.000 claims description 23
- 230000002787 reinforcement Effects 0.000 claims description 7
- 239000004568 cement Substances 0.000 claims description 6
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- 230000003014 reinforcing effect Effects 0.000 description 2
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- E—FIXED CONSTRUCTIONS
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- 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
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- E—FIXED CONSTRUCTIONS
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- 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
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
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Abstract
The invention relates to a combined supporting structure system for realizing large-span and small-clear-distance tunnels and a construction method thereof. The invention solves the difficult problems of simultaneous concentration and close-proximity close excavation of multiple sections with super-large span, super-small clear distance and the like, greatly reduces the bias voltage and stress concentration risk generated by the sudden change of the special-shaped section, shortens the construction period, simultaneously avoids the adverse effect of large floor area on the surrounding environment through ground excavation, can meet the requirement of internally constructing a large-span tunnel structure only by utilizing the in-situ space in the tunnel, has stronger adaptability and can also meet the harsh requirement of protecting the surrounding environment.
Description
Technical Field
The invention belongs to the technical field of tunnel engineering, and particularly relates to a combined supporting structure system for realizing a large-span and small-clear-distance tunnel and a construction method thereof.
Background
When a subway line needs to be provided with two crossed parking lines, the subway line is generally placed in a subway station and is constructed by adopting an open excavation method, and sometimes the two parking lines need to be brought into an interval tunnel and a large-span tunnel section is arranged according to the requirements of line laying, station burial depth, construction method and the like; under the influence of line spacing, the large-span tunnel is longitudinally accessed into two ultra-small clear distance tunnels.
The conventional large-span tunnel is excavated by adopting a double-side-wall pit guiding method, is influenced by construction period, excavation working surface, construction equipment, surrounding environment and the like, and does not have construction space of the traditional double-side-wall pit guiding method. The ultra-small clear distance tunnel has extremely large risk, is generally solved by measures such as enlarging the line distance, arranging a safety isolation pile and the like, is influenced by technical requirements of a line plane, the buried depth of the line, the ground environment and the like, and does not have conditions for taking the measures.
Disclosure of Invention
The invention aims to provide a combined supporting structure system for realizing a large-span and small-clear-distance tunnel and a construction method thereof, which solve the problem of simultaneous concentration and close-proximity close excavation of multiple sections such as an ultra-large span and an ultra-small clear distance, greatly reduce the bias voltage and stress concentration risk caused by abnormal section mutation, realize that an end well is not required to be provided for a station or a temporary vertical well working surface is not required to be added according to the conventional method, greatly shorten the working time, simultaneously avoid the adverse effect of large floor area to the surrounding environment through ground excavation, and meet the requirement of constructing a large-span tunnel structure inside only by utilizing the in-situ space in a tunnel.
The technical scheme adopted by the invention is as follows:
realize the joint supporting construction system of big span, little clear distance tunnel, its characterized in that:
the combined supporting structure system sequentially comprises an O-shaped supporting structure of an ultra-small clear distance tunnel, a variable O-shaped supporting structure of an expanding excavation section and a variable O-shaped supporting structure of a large-span tunnel along the tunnel excavation direction;
the O-shaped supporting structure of the ultra-small clear distance tunnel is used for a left line ultra-small clear distance tunnel and a right line ultra-small clear distance tunnel, wherein the left line is a double line, the right line is a single line, the left line and the right line are both in an ellipse-like O shape, and the cross sections of the left line and the right line are the same along the horizontal excavation direction;
the variable O-shaped supporting structure of the large-span tunnel is used for the large-span tunnel and is in an arch-shaped O shape, the height of the initial section is variable along the horizontal excavation direction, and the initial section is transited to form a stable large-span tunnel supporting structure;
the variable O-shaped supporting structure of the expanded excavation section is used for expanding excavation section tunnels, and a raising transition is formed between the O-shaped supporting structure of the ultra-small clear distance tunnel and the variable O-shaped supporting structure of the large-span tunnel to realize expansion, so that a combined supporting system is formed.
The ultra-small clear distance O-shaped tunnel is constructed by adopting a subsection excavation method, the O-shaped curvatures of the left and right line tunnels can be flexibly set, the stability calculation requirement of the middle clamping rock pillar needs to be met, the left and right line temporary profile steel cross braces are erected on the middle rock pillar at the same time, and the tie anchor rods are arranged to reinforce the middle rock pillar and are closed into a whole with the ultra-small clear distance tunnel O-shaped supporting structure.
Expand the tunnel section of digging the variable O type supporting construction of section and expand from one side of super little clear distance tunnel and dig, have the vault and choose the high inclined plane, the slope on inclined plane is no longer than 1: 0.25.
the O-shaped variable supporting structure of the expanding excavation section is provided with two rows of small guide pipes, the small guide pipes are obliquely arranged upwards and are arranged in a quincunx shape, and the small guide pipes are welded with the grid steel frame in a supporting mode.
And each grid of the O-shaped supporting structure with the variable digging section is supported by temporary section steel, and two grid steel frames are longitudinally tensioned by reinforcing steel bars.
The temporary section steel supporting positions of the O-shaped supporting structure with the variable expanding and excavating section are provided with foot locking anchor rods.
The O-shaped supporting structure of the ultra-small clear distance tunnel is transited to the large-span tunnel variable O-shaped supporting structure through longitudinal and transverse expansion of the expanding excavation section variable O-shaped supporting structure, the space of the side wall of the large-span tunnel variable O-shaped supporting structure is provided with double rows of small guide pipes for grouting and reinforcement, the upper part of a rock pillar in the large-span tunnel is excavated in a transverse subsection mode, after a top cavity is formed, arch cover concrete is applied, side wall and arch foot concrete is applied, and the arch foot is in a right-angle mode.
The long-span tunnel arch springing is fixed by a plurality of locking anchor rods and temporary cross braces, after the arch cover is stably formed, the middle rock pillar is broken in a subsection mode, and finally the inverted arch is constructed.
Plain concrete is back-filled in the inclined cavity of the variable O-shaped supporting structure of the expanding excavation section.
The construction method for realizing the combined supporting structure system of the large-span and small-clear-distance tunnel is characterized by comprising the following steps of:
the method comprises the following steps:
the method comprises the following steps: firstly, constructing an O-shaped supporting structure of a tunnel with ultra-small clear distance between a left line and a right line, erecting a grid steel frame after excavating, erecting double rows of small guide pipes in the range of 120 degrees of an arch part, welding the small guide pipes on the grid steel frame, adopting phi 42 advanced small guide pipes, enabling L =4.0m, enabling the circumferential distance to be 0.3m and the longitudinal distance to be 2.5m, adopting 1:1 cement paste for grouting, arranging phi 22 side walls and arranging side wall anchor rods with L =3 m;
step two: a row of temporary supports are erected at a position 0.5m away from the junction of an arch wall in the straight edge wall part of the O-shaped support structure grid steel frame of the ultra-small clear distance tunnel, the temporary supports adopt 20I-shaped steel, the longitudinal distance is 1m, the temporary cross braces are erected simultaneously, the left and right pairs of supports are arranged, a pair-pulling anchor rod is arranged to reinforce a middle rock pillar, and the middle rock pillar is welded with the O-shaped support structure of the ultra-small clear distance tunnel and is closed into a whole;
step three: two phi 22 locking anchor rods are arranged at the temporary supporting angular points in the excavation process of the arch foot position of each grid steel frame, and L =4 m;
step four: the construction of the variable O type section structure of the section of digging begins to expand after the O type supporting construction of super little clear distance tunnel supports stably, and the slope that strictly controls to choose to increase to dig is not more than 1:0.25, strictly controlling the longitudinal spacing of the grid steel frames of the tunnel at the high expanding excavation section to be not more than 0.5m, densely distributing the grid steel frames at 3m without spacing when expanding excavation is started, longitudinally and transversely digging and widening the variable O-shaped support, longitudinally tensioning the variable O-shaped support grid by using phi 22 steel bars, and finally forming O-shaped supports of guide pits on two side walls of the large-span tunnel;
step five: the method comprises the following steps that the upper part of a middle rock pillar is excavated in a horizontal subsection mode by utilizing the side wall space of a tunnel in the expanded excavation section and the specified mileage, the subsection distance is not less than 6m, a close-packed grid and two rows of small guide pipes are arranged during the horizontal subsection excavation, the parameter is phi 42, L =3.0m, the circumferential distance is 0.3m, the longitudinal distance is 1.5m, and 1:1 cement slurry is adopted for grouting;
step six: constructing an arch cover support after a cavity at the top of the large-span tunnel is formed, constructing an arch part of an O-shaped support of the large-span tunnel, constructing a side wall and an arch springing support, wherein the arch springing is in a right-angle type, and the right-angle horizontal section is not less than 3 m;
step seven: the arch foot is fixed by a plurality of phi 22 foot locking anchor rods and I-steel temporary cross braces, after the arch cover is stably formed, the middle rock pillar is broken in sections, finally, an inverted arch is constructed, and finally, a closed-loop arch-shaped O-shaped supporting system of the large-span tunnel is formed.
The invention has the following advantages:
the invention is provided with a closed grid and a locking anchor rod, a small conduit welded on the grid, a temporary section steel support in a tunnel support, a tie bar for reinforcing the longitudinal connection of the combined support system, a counter-pull anchor rod and the like in a combined support structure system for realizing a large-span and small-clear-distance tunnel, wherein the steel, the cement mortar, the machinery for driving the small conduit, the trolley in the hole for building the grid, the steel bar welding equipment, the fixed anchor bolt for building the temporary section steel support and the like are all conventional materials or equipment, the corresponding size of the equipment is a conventional type in engineering, the equipment is convenient to process, manufacture and purchase, the length of the small conduit can be dynamically adjusted and processed according to the stability of surrounding rocks and the geological conditions on site, the dynamic optimization adjustment is carried out according to the reinforcement effect, and the equipment has strong operability.
The structural system directly excavates and supports in the tunnel, does not need to require a station to provide an end well or additionally provide a temporary vertical shaft working surface according to a conventional method, can realize ultra-short distance laying of a line and building space requirements, and has the characteristics of flexibility, changeability, strong adaptability, safety, reliability and the like. The tunnel expanding excavation and raising slope is controlled within 1:0.25 according to the stratum stability condition, the ultra-small clear distance tunnel is matched with the curvature of the O-shaped tunnel through rock pillar stability calculation, and the distance setting of the grid steel frame, the temporary steel support arrangement and the longitudinal tie bars can be flexibly adjusted according to the excavation stratum condition. Through the advanced stratum pre-reinforcement measure of the small guide pipe, the intermediate rock pillar is reinforced by the counter-pull anchor rod, the slope of the tunnel expanding excavation section is controlled, the tunnel grid steel frame is encrypted, the internal temporary steel supports and the longitudinal tie bars are arranged, the safety of the expanding excavation section structure can be realized, and finally various O-shaped tunnels are connected to form a combined supporting system, so that the structural integrity and safety are ensured. The variable combined supporting system is flexible in arrangement, has strong adaptability and can meet the harsh requirement of protecting the surrounding environment, and the variable combined supporting system can meet the requirement of constructing the large-span tunnel structure inside only by utilizing the in-situ space in the tunnel. Therefore, the invention has higher economic benefit and social benefit and wide application prospect in the urban rail transit industry.
Drawings
FIG. 1 is a structure diagram of an O-shaped combined support with ultra-small clear distance
Fig. 2 is a structure diagram of a variable O-shaped combined support (left hole).
Fig. 3 is a structure diagram of a variable O-shaped combined support (right hole).
Fig. 4 is a structure view of a variable O-shaped combined support.
Fig. 5 is a sectional view of the combined supporting structure A-A.
Fig. 6 is a detail construction view of a combined supporting foot-locking anchor rod.
Fig. 7 is a detail construction diagram of a combined supporting small conduit.
The labels in the figure are: 1-left-hole small-section horseshoe-shaped O-shaped supporting structure, 2-right-hole small-section horseshoe-shaped O-shaped supporting structure, 3-temporary profile steel support, 4-locking anchor rods, 5-left-hole expanded-excavation-section variable O-shaped supporting structure, 6-right-hole expanded-excavation-section variable O-shaped supporting structure, 7-left-hole large-span tunnel subsection pilot tunnel O-shaped supporting structure, 8-right-hole large-span tunnel subsection pilot tunnel O-shaped supporting structure, 9-large-span tunnel variable O-shaped supporting arch structure, 10-large-span tunnel O-shaped supporting arch structure, 11-small guide pipe, 12-plain concrete, 13-welded steel plate, 14-fixed steel plate, 15-side wall anchor rods and 16-split anchor rods.
Detailed Description
The present invention will be described in detail with reference to specific embodiments.
The invention relates to a combined supporting structure system for realizing large-span and small-clear-distance tunnels, which enriches the excavation mode of the existing large-span and small-clear-distance tunnels in a centralized manner, can directly excavate and support the existing tunnel holes, does not need to provide an end well for a station or add a temporary vertical shaft working surface according to the conventional method, and then adopts fussy processes such as CD, CRD and the like for construction, does not need to ask lines to pull line spacing or carry out isolation treatment, widens the method for realizing the centralized excavation of the large-span tunnels and the small-clear-distance tunnels, saves investment and saves construction period, has the characteristics of flexibility, strong adaptability, safety, reliability, conventional and convenient materials and the like, and provides a brand new idea for realizing the safe excavation and engineering quality of the large-span and small-clear-distance tunnels.
The combined supporting structure system sequentially comprises an O-shaped supporting structure of an ultra-small clear distance tunnel, a variable O-shaped supporting structure of an expanding excavation section and a variable O-shaped supporting structure of a large-span tunnel along the tunnel excavation direction; the O-shaped supporting structure of the ultra-small clear distance tunnel is used for a left line ultra-small clear distance tunnel and a right line ultra-small clear distance tunnel, wherein the left line is a double line, the right line is a single line, the left line and the right line are both in an ellipse-like O shape, and the cross sections of the left line and the right line are the same along the horizontal excavation direction; the variable O-shaped supporting structure of the large-span tunnel is used for the large-span tunnel and is in an arch-shaped O shape, the height of the initial section is variable along the horizontal excavation direction, and the initial section is transited to form a stable large-span tunnel supporting structure; the variable O-shaped supporting structure of the expanded excavation section is used for expanding excavation section tunnels, and a raising transition is formed between the O-shaped supporting structure of the ultra-small clear distance tunnel and the variable O-shaped supporting structure of the large-span tunnel to realize expansion, so that a combined supporting system is formed.
The O-shaped tunnel with the ultra-small clear distance is constructed by adopting a subsection excavation method, the O-shaped curvatures of the tunnel with the left line and the tunnel with the right line can be flexibly set, the calculation requirement of the stability of the middle clamping rock pillar needs to be met, the temporary profile steel cross braces 3 with the left line and the right line are erected on the middle rock pillar at the same time, the opposite pulling anchor rods 16 are arranged to reinforce the middle rock pillar, and the O-shaped tunnel with the ultra-small clear distance and the O-shaped supporting structures 1 and 2 are closed into a whole.
Expand the tunnel section of digging the variable O type supporting construction of section and expand from small cross section tunnel one side and dig, have the vault and choose high inclined plane, the slope on inclined plane is no longer than 1: 0.25. the variable O-shaped supporting structure of the expanding excavation section is provided with two rows of small guide pipes 11, the small guide pipes are obliquely arranged upwards and are arranged in a quincunx shape, and the small guide pipes 11 are welded with the grid steel frame in a supporting mode. And each grid of the O-shaped supporting structure with the variable digging section is supported by 3 temporary section steel, and two grid steel frames are longitudinally tensioned by reinforcing steel bars. The temporary steel supports 3 of the O-shaped supporting structure with the variable expanding and excavating section are all provided with a foot locking anchor rod 4. Plain concrete 12 is back-filled in the inclined cavity of the variable O-shaped supporting structure of the expanding excavation section.
The O-shaped supporting structure of the ultra-small clear distance tunnel is transited to the large-span tunnel variable O-shaped supporting structure through longitudinal and transverse expansion of the expanding excavation section variable O-shaped supporting structure, the space of the side wall of the large-span tunnel variable O-shaped supporting structure is provided with double rows of small guide pipes for grouting and reinforcement, the upper part of a rock pillar in the large-span tunnel is excavated in a transverse subsection mode, after a top cavity is formed, arch cover concrete is applied, side wall and arch foot concrete is applied, and the arch foot is in a right-angle mode.
The long-span tunnel arch springing is fixed by a plurality of locking anchor rods 4 and temporary cross braces, and after the arch cover is stably formed, the middle rock pillar is broken in a subsection mode, and finally, the inverted arch is constructed. Plain concrete 12 is back-filled in the inclined cavity of the variable O-shaped supporting structure of the expanding excavation section.
In the whole process, the stability measures of the rock pillar supported by the O-shaped supporting structure of the ultra-small clear distance tunnel need to be strictly executed, and the stability measures comprise the adoption of stabilizing measures such as counter-pulling anchor rods, symmetrically arranging cross braces, reasonably fitting the curvature of the O-shaped tunnel and the like; in addition, the expansion degree of the variable O-shaped support of the transition section is strictly controlled, including a raised slope and a transverse cut range, a longitudinal steel bar fastening combined support system is adopted, a foot fulcrum of the O-shaped support system is stabilized by a foot locking anchor rod, and the like, which are the key points of the success of the whole support system.
The combined supporting structure system has the following characteristics:
firstly, in a complex environment, the stability of the O-shaped supporting structure of the ultra-small clear distance tunnel for clamping the rock pillar is ensured by adopting stabilizing measures such as oppositely pulling anchor rods, symmetrically arranging cross braces, reasonably fitting the curvature of the O-shaped tunnel and the like; by adopting the pre-reinforcement measure of the stratum of the small conduit of the arch part, the excavation slope of the variable O-shaped supporting tunnel is strictly controlled, the stabilization measures of grid steel frame close arrangement, foot locking anchor rods and the like are adopted, and the connection of the temporary steel support inside the tunnel and the longitudinal supporting structure is combined, so that the raising conversion of the variable O-shaped supporting structure system is realized. Secondly, the construction sequence of firstly constructing the O-shaped guide pits on the two sides and then constructing the middle tunnel arch cover is adopted, the middle rock pillar is reserved all the time in the whole construction process, and finally the middle rock pillar is broken after the arch cover, the side wall and the arch foot secondary lining are stabilized, and the O-shaped supporting structure formed by excavating the small-section tunnel, the expanded excavation section variable O-shaped tunnel supporting structure and the large-span tunnel variable O-shaped supporting structure form a combined supporting system together, so that the structural type of the large-span tunnel is realized.
The construction method for realizing the combined supporting structure system of the large-span and small-clear-distance tunnel comprises the following steps of:
the method comprises the following steps: firstly, constructing an O-shaped supporting structure of a tunnel with ultra-small clear distance between a left line and a right line, erecting a grid steel frame after excavating, erecting double rows of small guide pipes in the range of 120 degrees of an arch part, welding the small guide pipes on the grid steel frame, adopting phi 42 advanced small guide pipes, enabling L =4.0m, enabling the circumferential distance to be 0.3m and the longitudinal distance to be 2.5m, adopting 1:1 cement paste for grouting, arranging phi 22 side walls and arranging side wall anchor rods with L =3 m;
step two: a row of temporary supports are erected at a position 0.5m away from the junction of an arch wall in the straight edge wall part of the O-shaped support structure grid steel frame of the ultra-small clear distance tunnel, the temporary supports adopt 20I-shaped steel, the longitudinal distance is 1m, the temporary cross braces are erected simultaneously, the left and right pairs of supports are arranged, a pair-pulling anchor rod is arranged to reinforce a middle rock pillar, and the middle rock pillar is welded with the O-shaped support structure of the ultra-small clear distance tunnel and is closed into a whole;
step three: two phi 22 locking anchor rods 4 are arranged at the temporary support angular points in the excavation process of the arch foot position of each grid steel frame, and L =4 m;
step four: the construction of the variable O type section structure of the section of digging begins to expand after the O type supporting construction of super little clear distance tunnel supports stably, and the slope that strictly controls to choose to increase to dig is not more than 1:0.25, strictly controlling the longitudinal spacing of the grid steel frames of the tunnel at the high expanding excavation section to be not more than 0.5m, densely distributing the grid steel frames at 3m without spacing when expanding excavation is started, longitudinally and transversely digging and widening the variable O-shaped support, longitudinally tensioning the variable O-shaped support grid by using phi 22 steel bars, and finally forming O-shaped supports of guide pits on two side walls of the large-span tunnel;
step five: the method comprises the following steps that the upper part of a middle rock pillar is excavated in a horizontal subsection mode by utilizing the side wall space of a tunnel in the expanded excavation section and the specified mileage, the subsection distance is not less than 6m, a close-packed grid and two rows of small guide pipes are arranged during the horizontal subsection excavation, the parameter is phi 42, L =3.0m, the circumferential distance is 0.3m, the longitudinal distance is 1.5m, and 1:1 cement slurry is adopted for grouting;
step six: constructing an arch cover support after a cavity at the top of the large-span tunnel is formed, constructing an arch part of an O-shaped support of the large-span tunnel, constructing a side wall and an arch springing support, wherein the arch springing is in a right-angle type, and the right-angle horizontal section is not less than 3 m;
step seven: the arch foot is fixed by a plurality of phi 22 foot locking anchor rods and I-steel temporary cross braces, after the arch cover is stably formed, the middle rock pillar is broken in sections, finally, an inverted arch is constructed, and finally, a closed-loop arch-shaped O-shaped supporting system of the large-span tunnel is formed.
The key point of the successful implementation of the invention is that the fitting curvature of the O-shaped tunnel, the expansion degree of the variable O-shaped support and the stabilization effect of the middle rock pillar of the ultra-small clear distance and the large-span tunnel are strictly controlled in the whole process, the design concept of 'strong support' is adopted in the implementation engineering, and the design idea of multiple pivots is utilized, such as the reinforcement measure of the pulling anchor rod to stabilize the rock pillar and the foot of the locking foot anchor rod to stabilize the variable O-shaped combined support system, and the middle part of the I-shaped steel to stabilize the support system, so as to ensure the safety of the support system, of course, the surrounding rock conditions are varied, and the whole design process still needs to follow: the principle of advancing, grouting tightly, short excavation, strong support, quick sealing and frequent measurement of pipes. The steel, cement mortar, machinery for driving the small guide pipe, a trolley in a hole for erecting the grating and the like are conventional materials or equipment, can be dynamically optimized and adjusted according to the reinforcing effect, and have strong operability; the fitting curvature of the O-shaped tunnel is adjusted adaptively according to the calculation of the stability of the power, the ultra-small clear distance middle rock pillar can ensure the stability and safety of the O-shaped tunnel, the expanding excavation and raising slope of the transition section O-shaped tunnel is controlled within 1:0.25 according to the stable condition of the stratum to change adaptively, and the distance between the grid steel frame, the temporary profile steel support arrangement and the longitudinal tie bars can be adjusted flexibly according to the condition of the excavated stratum. The variable combined supporting system solves the problem of simultaneous concentrated and close-proximity excavation of multiple sections with super-large span, super-small clear distance and the like, greatly reduces the bias voltage and stress concentration risk generated by abnormal section mutation, realizes that the station is not required to provide an end well or additionally provided with a temporary vertical well working surface according to the conventional method, greatly shortens the working time, avoids the adverse effect of large floor area on the surrounding environment through ground excavation, can meet the requirement of constructing a large-span tunnel structure inside only by utilizing the in-situ space in a tunnel, is flexible in arrangement, has strong adaptability, and can meet the harsh requirement of surrounding environment protection. Therefore, the invention has higher economic benefit and social benefit and wide application prospect in the urban rail transit industry.
The invention is not limited to the examples, and any equivalent changes to the technical solution of the invention by a person skilled in the art after reading the description of the invention are covered by the claims of the invention.
Claims (10)
1. Realize the joint supporting construction system of big span, little clear distance tunnel, its characterized in that:
the combined supporting structure system sequentially comprises an O-shaped supporting structure of an ultra-small clear distance tunnel, a variable O-shaped supporting structure of an expanding excavation section and a variable O-shaped supporting structure of a large-span tunnel along the tunnel excavation direction;
the O-shaped supporting structure of the ultra-small clear distance tunnel is used for a left line ultra-small clear distance tunnel and a right line ultra-small clear distance tunnel, wherein the left line is a double line, the right line is a single line, the left line and the right line are both in an ellipse-like O shape, and the cross sections of the left line and the right line are the same along the horizontal excavation direction;
the variable O-shaped supporting structure of the large-span tunnel is used for the large-span tunnel and is in an arch-shaped O shape, the height of the initial section is variable along the horizontal excavation direction, and the initial section is transited to form a stable large-span tunnel supporting structure;
the variable O-shaped supporting structure of the expanded excavation section is used for expanding excavation section tunnels, and a raising transition is formed between the O-shaped supporting structure of the ultra-small clear distance tunnel and the variable O-shaped supporting structure of the large-span tunnel to realize expansion, so that a combined supporting system is formed.
2. The combined supporting structure system for realizing the large-span and small-clear-distance tunnel according to claim 1, wherein:
the ultra-small clear distance O-shaped tunnel is constructed by adopting a subsection excavation method, the O-shaped curvatures of the left and right line tunnels can be flexibly set, the stability calculation requirement of the middle clamping rock pillar needs to be met, the left and right line temporary profile steel cross braces are erected on the middle rock pillar at the same time, and the tie anchor rods are arranged to reinforce the middle rock pillar and are closed into a whole with the ultra-small clear distance tunnel O-shaped supporting structure.
3. The combined supporting structure system for realizing the large-span and small-clear-distance tunnel according to claim 2, wherein:
expand the tunnel section of digging the variable O type supporting construction of section and expand from one side of super little clear distance tunnel and dig, have the vault and choose the high inclined plane, the slope on inclined plane is no longer than 1: 0.25.
4. the combined supporting structure system for realizing the large-span and small-clear-distance tunnel according to claim 3, wherein:
the variable O-shaped supporting structure of the expanding excavation section is provided with two rows of small guide pipes (11), the small guide pipes are obliquely arranged upwards and are arranged in a quincunx shape, and the small guide pipes (11) are welded with the grid steel frame in a supporting mode.
5. The combined supporting structure system for realizing the large-span and small-clear-distance tunnel according to claim 4, wherein:
and each grid of the O-shaped supporting structure with the variable digging section is supported by temporary section steel (3), and two grid steel frames are longitudinally tensioned by reinforcing steel bars.
6. The combined supporting structure system for realizing the large-span and small-clear-distance tunnel according to claim 5, wherein:
and temporary section steel supports (3) of the O-shaped supporting structure with variable expanding and excavating sections are all provided with locking anchor rods (4).
7. The combined supporting structure system for realizing the large-span and small-clear-distance tunnel according to claim 6, wherein:
the O-shaped supporting structure of the ultra-small clear distance tunnel is transited to the large-span tunnel variable O-shaped supporting structure through longitudinal and transverse expansion of the expanding excavation section variable O-shaped supporting structure, the space of the side wall of the large-span tunnel variable O-shaped supporting structure is provided with double rows of small guide pipes for grouting and reinforcement, the upper part of a rock pillar in the large-span tunnel is excavated in a transverse subsection mode, after a top cavity is formed, arch cover concrete is applied, side wall and arch foot concrete is applied, and the arch foot is in a right-angle mode.
8. The combined supporting structure system for realizing the large-span and small-clear-distance tunnel according to claim 7, wherein:
the arch foot of the long-span tunnel is fixed by a plurality of foot-locking anchor rods (4) and temporary cross braces, and after the arch cover is stably formed, the middle rock pillar is broken in a subsection mode, and finally the inverted arch is constructed.
9. The combined supporting structure system for realizing the large-span and small-clear-distance tunnel according to claim 8, wherein:
plain concrete (12) is back-filled in the inclined cavity of the variable O-shaped supporting structure of the expanding and excavating section.
10. The construction method for realizing the combined supporting structure system of the large-span and small-clear-distance tunnel is characterized by comprising the following steps of:
the method comprises the following steps:
the method comprises the following steps: firstly, constructing an O-shaped supporting structure of a tunnel with ultra-small clear distance between a left line and a right line, erecting a grid steel frame after excavating, erecting double rows of small guide pipes in the range of 120 degrees of an arch part, welding the small guide pipes on the grid steel frame, adopting phi 42 advanced small guide pipes, enabling L =4.0m, enabling the circumferential distance to be 0.3m and the longitudinal distance to be 2.5m, adopting 1:1 cement paste for grouting, arranging phi 22 side walls and arranging side wall anchor rods with L =3 m;
step two: a row of temporary supports are erected at a position 0.5m away from the junction of an arch wall in the straight edge wall part of the O-shaped support structure grid steel frame of the ultra-small clear distance tunnel, the temporary supports adopt 20I-shaped steel, the longitudinal distance is 1m, the temporary cross braces are erected simultaneously, the left and right pairs of supports are arranged, a pair-pulling anchor rod is arranged to reinforce a middle rock pillar, and the middle rock pillar is welded with the O-shaped support structure of the ultra-small clear distance tunnel and is closed into a whole;
step three: two phi 22 locking anchor rods (4) are arranged at the temporary supporting angular points in the excavation process of the arch foot position of each grid steel frame, and L =4 m;
step four: the construction of the variable O type section structure of the section of digging begins to expand after the O type supporting construction of super little clear distance tunnel supports stably, and the slope that strictly controls to choose to increase to dig is not more than 1:0.25, strictly controlling the longitudinal spacing of the grid steel frames of the tunnel at the high expanding excavation section to be not more than 0.5m, densely distributing the grid steel frames at 3m without spacing when expanding excavation is started, longitudinally and transversely digging and widening the variable O-shaped support, longitudinally tensioning the variable O-shaped support grid by using phi 22 steel bars, and finally forming O-shaped supports of guide pits on two side walls of the large-span tunnel;
step five: the method comprises the following steps that the upper part of a middle rock pillar is excavated in a horizontal subsection mode by utilizing the side wall space of a tunnel in the expanded excavation section and the specified mileage, the subsection distance is not less than 6m, a close-packed grid and two rows of small guide pipes are arranged during the horizontal subsection excavation, the parameter is phi 42, L =3.0m, the circumferential distance is 0.3m, the longitudinal distance is 1.5m, and 1:1 cement slurry is adopted for grouting;
step six: constructing an arch cover support after a cavity at the top of the large-span tunnel is formed, constructing an arch part of an O-shaped support of the large-span tunnel, constructing a side wall and an arch springing support, wherein the arch springing is in a right-angle type, and the right-angle horizontal section is not less than 3 m;
step seven: the arch foot is fixed by a plurality of phi 22 foot locking anchor rods and I-steel temporary cross braces, after the arch cover is stably formed, the middle rock pillar is broken in sections, finally, an inverted arch is constructed, and finally, a closed-loop arch-shaped O-shaped supporting system of the large-span tunnel is formed.
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