CN112012763B - Construction method of double-layer primary support multi-arch tunnel structure - Google Patents

Construction method of double-layer primary support multi-arch tunnel structure Download PDF

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CN112012763B
CN112012763B CN202010718529.2A CN202010718529A CN112012763B CN 112012763 B CN112012763 B CN 112012763B CN 202010718529 A CN202010718529 A CN 202010718529A CN 112012763 B CN112012763 B CN 112012763B
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tunnel
layer
arch
main
concrete
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CN112012763A (en
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柏署
李瑜
张进华
易震宇
傅立新
杨雄
龚峰
杨磊
吴佳
尹俊涛
肖鹏
万志文
赵辉雄
史晓琼
王木群
熊建军
蔡丽琴
黄欣
张鹏
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Third Engineering Co Ltd of China Railway 25th Bureau Group Co Ltd
Hunan Provincial Communications Planning Survey and Design Institute Co Ltd
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Hunan Provincial Communications Planning Survey and Design Institute Co Ltd
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    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D9/00Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
    • E21D9/14Layout of tunnels or galleries; Constructional features of tunnels or galleries, not otherwise provided for, e.g. portals, day-light attenuation at tunnel openings
    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/04Lining with building materials
    • E21D11/10Lining 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
    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/14Lining predominantly with metal
    • E21D11/15Plate linings; Laggings, i.e. linings designed for holding back formation material or for transmitting the load to main supporting members
    • E21D11/152Laggings made of grids or nettings
    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/38Waterproofing; Heat insulating; Soundproofing; Electric insulating
    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21FSAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
    • E21F16/00Drainage
    • E21F16/02Drainage of tunnels
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/20Hydro energy

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  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Structural Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Environmental & Geological Engineering (AREA)
  • Lining And Supports For Tunnels (AREA)

Abstract

The invention discloses a construction method of a double-layer primary support multi-arch tunnel structure, wherein the number of multiple arches of the multi-arch tunnel structure is more than or equal to 3, the multi-arch tunnel structure comprises 2 auxiliary tunnels, at least two intermediate walls and a main tunnel arranged between two adjacent intermediate walls, and the 2 auxiliary tunnels are respectively positioned on two sides of the multi-arch tunnel. In the scheme of the application, the main tunnel is constructed before the auxiliary tunnel, and each main tunnel comprises a first layer of primary support, a second layer of primary support and a secondary lining; the secondary primary support independent ring formation can effectively resist excavation disturbance during construction of adjacent tunnels, has the advantages of reinforcing support strength, isolating the influence of excavation of adjacent tunnels, and protecting the secondary lining, thereby avoiding the situation that cracks and water seepage occur in the constructed secondary lining. Meanwhile, waterproof and drainage measures are more convenient to apply between the primary support of the second layer and the secondary lining, so that the defect that the traditional multi-arch tunnel is difficult to drain water can be overcome.

Description

Construction method of double-layer primary support multi-arch tunnel structure
Technical Field
The invention relates to the field of tunnel construction, in particular to a construction method of a double-layer primary support multi-arch tunnel structure.
Background
In China, the structural form of the tunnel is mostly a double-hole separation type, and rich theories and practical experiences are accumulated in the construction of the structural form. However, in areas with special geological and topographic conditions, due to comprehensive consideration of factors such as the limitation of the overall route line and the bridge-tunnel connection mode, the double-hole separated tunnel is often difficult to realize. In a mountain and heavy hill area and in a basic farmland and urban land range with precious land resources, the multi-arch tunnel has the characteristics of small occupied area, high underground space utilization rate and the like, and becomes an important structural form. In addition, with the increase of the people's demand for convenient and smooth traffic, the traditional bidirectional four-lane and six-lane tunnels cannot meet the increasing traffic demand. In recent years, examples of super-large span double-arch, three-arch and four-arch projects appear, such as a six-lane double-arch highway tunnel of a Liujia bay of a winding plateau highway, a three-arch tunnel surrounding a region from a grassland slope of No. 2 line of a Xian subway to a Xiaozhai region, a three-arch tunnel between a Paiki 10 line of a Beijing subway and a Paeonia garden station-Jiandein gate station region, a four-arch tunnel adopted in a first-stage project of a first line of a Harbin subway, and the like. The heart-washing tunnel of the silver star road in Changsha city adopts a bidirectional ten-lane four-arch scheme, the excavation width is about 63m, the length is about 497m, the excavation width of the tunnel is far more than that of the fresh four-arch tunnel projects of domestic highways, subways and municipal works, and the project scale is the first of domestic.
The double-arch tunnel has a complex structure, and is excavated and supported in a staggered manner, so that the conversion between the stress of surrounding rock and the stress of a lining becomes very complex, and the stress distribution of the surrounding rock and the stress and deformation of each part of the lining are difficult to accurately solve in the tunnel excavation process; the multi-arch tunnel structure and construction are complex, the waterproof problem of the wild goose-shaped part at the top of the wall in the tunnel is prominent, and systematic and comprehensive research needs to be carried out from three aspects of structural design, waterproof and drainage materials and construction process. With the gradual appearance of three-arch and four-arch tunnels in engineering application, the double-arch tunnel construction technology is taken as a basis, a plurality of technical obstacles exist in the construction of the multi-arch tunnel when being popularized, the original double-arch tunnel construction technology is used, and inherent technical problems of difficult construction method conversion, difficult determination of structure effective load, uncertain middle wall stress, serious crack control and water leakage problems and the like of the multi-arch tunnel are further amplified in the construction of the multi-arch tunnel.
In view of the problem that the safety of the multi-arch tunnel structure cannot be guaranteed, a new technical thought needs to be found urgently to solve the problem, so that the safety and the economy of the multi-arch tunnel construction are improved, and the requirement for quick construction is met.
Disclosure of Invention
The invention mainly aims to provide a construction method of a double-layer primary support multi-arch tunnel structure, and aims to solve the technical problems that cracks and water seepage are easy to occur in the construction process of the multi-arch tunnel structure.
In order to achieve the above object, the present invention provides a construction method of a double-decked preliminary bracing multi-arch tunnel structure, wherein the number of arches of the multi-arch tunnel structure is greater than or equal to 3, the multi-arch tunnel structure comprises 2 auxiliary tunnels, at least two intermediate walls and a main tunnel arranged between two adjacent intermediate walls, the 2 auxiliary tunnels are respectively located at two sides of the multi-arch tunnel, and the construction method comprises the steps of:
excavating a middle pilot tunnel of the first main tunnel, and pouring middle partition wall concrete in sections after excavation to form the middle partition wall;
excavating a tunnel portal of a first main tunnel;
constructing a first layer of primary support of a first main tunnel: the first layer of primary support is formed on the wall top of the intermediate wall in a concrete spraying mode, and is connected with the intermediate wall into a whole under the action of concrete; the first layer of primary support is used for forming a safe construction space during tunnel portal construction;
constructing a second layer of primary support of the first main tunnel: erecting a section steel frame to be attached to an annular structure of the first-layer primary support, and forming the second-layer primary support in a concrete spraying manner; the primary support of the second layer forms a ring independently in the tunnel;
performing waterproof treatment and drainage treatment on the inner side of the primary support of the second layer;
and (3) constructing a secondary lining of the first main tunnel to finish final reinforcement: building a template by using a secondary lining trolley after building lining reinforcing steel bars, and pouring concrete to form a secondary lining, wherein the secondary lining is used for finally reinforcing and preventing water of the tunnel;
constructing other main tunnels, wherein the construction method of the other main tunnels is the same as that of the first main tunnel;
and finally constructing two auxiliary tunnels after constructing all the main tunnels, wherein the auxiliary tunnels adopt single-layer primary supporting structures or double-layer primary supporting structures.
Preferably, the step of performing waterproof treatment on the inner side of the second-layer primary support specifically includes:
and constructing a waterproof layer and a drainage system on the inner side of the primary support of the second layer, wherein the waterproof layer is made of geotextile and LDPE waterproof material.
Preferably, the step of excavating the middle pilot tunnel of the first main tunnel and pouring the middle partition concrete in sections after excavation to form the middle partition specifically includes:
spraying concrete on the hole wall of the excavated middle pilot hole in the excavating process;
fitting the hole wall profile of the middle pilot tunnel, arranging a plurality of steel arches in the middle pilot tunnel at intervals, and connecting adjacent steel arches through connecting ribs;
arranging a plurality of support frames on the ground of the middle pilot tunnel along the depth direction of the middle pilot tunnel, wherein the plurality of support frames are correspondingly connected with the plurality of steel arches one by one;
arranging a reinforcing mesh on the plurality of steel arch frames;
and casting middle partition wall concrete in the middle pilot tunnel in sections to form the middle partition wall.
Preferably, the step of excavating the tunnel portal of the first main tunnel specifically includes:
dividing a tunnel portal of a first main tunnel into a left portal and a right portal, excavating the left portal, arranging grouting small pipes at a left arch part for advanced pre-support, arranging left arch part steel frames in the tunnel, and connecting the left arch part steel frames with pre-buried steel frames in the intermediate wall; excavating the left tunnel portal for 30-40 m, then excavating the right tunnel portal, arranging the same grouting small guide pipe on the right arch part for advanced pre-support, and arranging a right arch part steel frame; and alternately excavating the left side hole and the right side hole until the tunnel hole of the whole main tunnel is excavated.
Preferably, the step of erecting the steel frame on the top of the mid-wall includes:
and erecting a profile steel frame on the top of the partition wall, connecting the profile steel frame with a steel frame embedded in the partition wall, and fixing the connection part in a welding or bolt locking mode.
Preferably, the construction method further comprises:
and numbering all the main tunnels in sequence from left to right or from right to left, and constructing the main tunnels in sequence according to the numbering.
Preferably, the secondary lining is made of steel reinforcement and concrete, and is formed into a ring separately.
Preferably, the thickness of the secondary lining is 35-45cm.
In the scheme of the application, the multi-arch tunnel structure comprises at least one main tunnel and two auxiliary tunnels, wherein the main tunnel is constructed in advance of the auxiliary tunnels, and each main tunnel comprises a first-layer primary support, a second-layer primary support and a secondary lining; the secondary primary support independent ring formation can effectively resist excavation disturbance during construction of adjacent tunnels, has the advantages of reinforcing support strength, isolating the influence of excavation of adjacent tunnels, and well protecting the secondary lining, thereby avoiding the situation that cracks and water seepage occur in the constructed secondary lining. Meanwhile, waterproof and drainage measures are more convenient to apply between the primary support of the second layer and the secondary lining, so that the defect that the traditional multi-arch tunnel is difficult to drain water can be overcome.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic structural view of a double-decker preliminary bracing multi-arch tunnel structure of the present invention;
FIG. 2 is a partial view of FIG. 1;
fig. 3 is a flow chart illustrating a construction method of a multi-arch tunnel structure according to the present invention.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
The reference numbers illustrate:
110-a first-layer primary support, 120-a second-layer primary support and 130-secondary lining;
210-single-layer primary support and 220-single-layer lining;
300-the intermediate wall.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all directional indicators (such as up, down, left, right, front, and back \8230;) in the embodiments of the present invention are only used to explain the relative positional relationship between the components, the motion situation, etc. in a specific posture (as shown in the attached drawings), and if the specific posture is changed, the directional indicators are changed accordingly.
In addition, the descriptions relating to "first", "second", etc. in the present invention are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature. In addition, technical solutions between the embodiments may be combined with each other, but must be based on the realization of the technical solutions by a person skilled in the art, and when the technical solutions are contradictory to each other or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
Referring to fig. 1 to 2, in order to achieve the above object, the present invention provides a multi-arch tunnel structure for double-deck preliminary bracing, wherein the number of arches of the multi-arch tunnel structure is greater than or equal to 3. The multi-arch tunnel structure can be three-arch, four-arch, five-arch or even six-arch. The drawings of the present embodiment illustrate a four-arch configuration as an example.
The multi-arch tunnel comprises 2 auxiliary tunnels, at least two intermediate walls 300 and a main tunnel arranged between two adjacent intermediate walls 300, wherein the 2 auxiliary tunnels are respectively positioned at two sides of the multi-arch tunnel, and each main tunnel comprises a first layer of primary supports 110, a second layer of primary supports 120 and a secondary lining 130; the first layer of preliminary bracing 110 is formed by a steel section frame and a sprayed concrete structure, the first layer of preliminary bracing 110 is arranged at the tops of two adjacent intermediate walls 300 in a spanning manner, the steel section frame of the first layer of preliminary bracing 110 is connected with a steel frame embedded in the intermediate walls 300 and is connected with the intermediate walls 300 into a whole through sprayed concrete; the second layer of primary supports 120 are arranged on the inner side of the first layer of primary supports 110 and are attached to the intermediate wall 300, and the second layer of primary supports 120 are formed by spraying concrete on a steel section frame and are independent rings; the secondary lining 130 is provided inside the secondary primary support 120.
Wherein the intermediate wall 300 serves to support the sides of the tunnel and serves as a construction foundation for the first-story preliminary bracing 110. The first-layer primary support 110 is connected with the intermediate wall 300 into a whole under the action of concrete; the first preliminary bracing 110 is used to form a safe construction space when constructing the tunnel portal. Further, the cross section of the primary support 110 of the first layer is arc-shaped, and supports the roof of the tunnel, and both ends of the primary support span the two adjacent intermediate walls 300.
The second-layer primary support 120 forms an annular structure, can effectively resist excavation disturbance during construction of adjacent tunnels, has the strength of reinforcing support, and has the function of isolating the influence of excavation of the adjacent tunnels, so that the secondary lining 130 is well protected. The second-layer primary support 120 may be formed by erecting steel frames to form a ring structure abutting against the first-layer primary support 110, and spraying concrete to form the second-layer primary support 120.
In the scheme of the application, the multi-arch tunnel structure comprises at least one main tunnel and two auxiliary tunnels, wherein the main tunnel is constructed in advance of the auxiliary tunnels, and each main tunnel comprises a first-layer primary support 110, a second-layer primary support 120 and a secondary lining 130; the secondary primary support 120 forms a ring independently, so that excavation disturbance in construction of adjacent tunnels can be effectively resisted, the secondary support has the advantages of reinforcing support strength, isolating the influence of excavation of adjacent tunnels, and well protecting the secondary lining 130, and the situation that cracks and water seepage occur in the constructed secondary lining 130 is avoided. Meanwhile, waterproof and drainage measures are more conveniently implemented between the primary support 120 on the second layer and the secondary lining 130, so that the defect that the traditional double-arch tunnel is difficult to waterproof is overcome. The multi-arch tunnel mid-board is provided with a plurality of holes, the partition wall is provided with a plurality of arch-shaped tunnels, the partition wall is provided with a plurality of holes, the holes are arranged on the partition wall, the partition wall is provided with a plurality of arch-shaped tunnels, the holes are arranged on the partition wall, and the partition wall is provided with a plurality of arch-shaped tunnels.
As a preferred embodiment of the present invention, the main tunnel further includes a waterproof layer provided between the secondary primary supports 120 and the secondary lining 130. The waterproof layer is made of a waterproof building material for isolating water from the outside of the secondary lining 130. The waterproof layer can adopt geotextile and an LDPE waterproof layer, and water is blocked outside the secondary lining to serve as a first waterproof measure. The cast concrete of the secondary lining adopts waterproof concrete more than C25 for casting, a deformation joint of a tunnel body can be provided with a middle-buried rubber waterstop, a construction joint is provided with a bentonite rubber water bar with a grouting pipe, and a construction longitudinal joint between the side wall foundation and the secondary lining of the arch wall should also be provided with the rubber waterstop as a second waterproof measure. In addition, a drainage system is arranged between the waterproof layer and the secondary lining 130, and a drainage ditch is reserved on the secondary lining 130. The water under the ground surface is gathered to the drainage ditch through the drainage system.
In a preferred embodiment of the present invention, the secondary lining 130 has a circular cross-section. The secondary lining 130 is arranged on the inner side of the primary support 120 on the second layer which forms a ring independently, so that the secondary lining 130 can also be arranged into a structure which forms a ring independently, and the support strength is effectively improved.
As a preferred embodiment of the present invention, the secondary tunnel is a single-layered preliminary bracing 210 structure. It should be noted that the auxiliary tunnels are tunnels located on two sides of the multi-arch tunnel, and after the construction of the main tunnel is completed, the construction of the auxiliary tunnels is performed. Since the main tunnel is previously constructed, disturbance is easily generated to the already constructed main tunnel when the adjacent tunnels are excavated, so that the secondary lining 130 of the main tunnel is cracked. And the auxiliary tunnel is constructed finally, so that the auxiliary tunnel is not disturbed after the construction is finished, and the cost can be saved by directly adopting the conventional single-layer primary support 210 structure.
Further, the auxiliary tunnel may include a single-layered preliminary bracing 210 and a single-layered lining 220, the single-layered preliminary bracing 210 is constructed of a steel section frame and a sprayed concrete structure, one end of the single-layered preliminary bracing 210 is erected on the top of the intermediate wall 300, the steel section frame of the single-layered preliminary bracing 210 is connected to a steel frame buried in the intermediate wall 300 and is integrated with the intermediate wall 300 by sprayed concrete; the single-layered lining 220 is provided inside the single-layered preliminary bracing 210.
As an embodiment of the present invention, the side surface of the intermediate wall 300 is an arc surface which is inwardly depressed, and the side surface of the intermediate wall 300 is connected to the arc inner side surface of the first preliminary bracing to form a semicircular inner wall surface. Wherein, the intermediate wall 300 may be formed by pouring concrete through a steel arch. During specific construction, a plurality of steel arch frames are arranged in the middle pilot tunnel at intervals, and adjacent steel arch frames are connected through connecting ribs. Arranging a plurality of support frames on the ground of the middle pilot tunnel along the depth direction of the middle pilot tunnel, wherein the plurality of support frames are connected with the plurality of steel arches in a one-to-one correspondence manner; and then reinforcing meshes are arranged on the plurality of steel arches, and concrete for the intermediate wall 300 is poured in the intermediate pilot tunnel in a segmented manner to form the intermediate wall 300. Further, an anchor rod extending toward the ground is further provided in the intermediate wall 300, the anchor rod is connected to the steel arch, and the anchor rod stably fixes the intermediate wall 300 to the ground.
Referring to fig. 3, in order to construct the multi-arch tunnel structure, the construction method of the present invention includes the following steps:
s10, excavating a middle pilot tunnel of the first main tunnel, and pouring middle partition wall concrete in a segmented mode after excavation to form the middle partition wall;
when the combined arch tunnel is constructed, a three-pilot-hole construction method or a middle pilot-main-hole construction method can be adopted. The three-pilot-hole method is that firstly, a middle pilot hole is excavated, then an intermediate wall is constructed, and then left and right pilot holes are respectively excavated. The main purpose of excavating the middle pilot tunnel is to construct an intermediate wall firstly. The middle pilot tunnel-main tunnel construction method is an efficient construction method widely used for double arch tunnel construction. And (3) excavating a large section by smooth blasting, excavating a through pilot tunnel by using supporting means such as an anchor, a spray, a net, a steel arch, an advanced conduit, an advanced pipe shed and the like, and pouring concrete of the intermediate wall.
S20, excavating a tunnel portal of the first main tunnel;
when the construction is carried out by adopting a pilot tunnel-main tunnel method, waterproof materials of the top of the middle partition wall are laid, concrete with the same label of the middle partition wall is backfilled, a long pipe shed is arranged for grouting, then the right tunnel is excavated for arching and temporary support, and meanwhile deformation observation of surrounding rocks is carried out. And after the right tunnel upper arch is pushed to a proper distance, excavating the left tunnel upper arch, well performing temporary support of the upper arch, and well performing deformation observation on surrounding rock.
S30, constructing a first layer of primary support of the first main tunnel: the first layer of primary support is formed on the wall top of the intermediate wall in a concrete spraying mode, and is connected with the intermediate wall into a whole under the action of concrete; the first layer of primary support is used for forming a safe construction space during tunnel portal construction;
the first-layer primary support is connected with the intermediate wall into a whole under the action of concrete by spraying the concrete, so that the strength and reliability of the support are enhanced.
S40, constructing a second-layer primary support of the first main tunnel: erecting a section steel frame to be attached to an annular structure of the first-layer primary support, and forming the second-layer primary support in a concrete spraying manner; the primary support of the second layer is independently formed into a ring in the tunnel;
in order to construct a second-layer primary support, the section steel frames can be firstly constructed on the inner side of the first-layer primary support, a plurality of section steel frames are welded into a ring structure, and concrete is sprayed to the section steel frames to form the second-layer primary support which is independent of the ring. The primary support of the second layer has stronger support strength and disturbance isolation capability. And the support strength of the primary support of the first layer is reinforced, and simultaneously the secondary lining is protected from being disturbed and cracked.
S50, performing waterproof treatment and drainage treatment on the inner side of the second-layer primary support: mainly used for laying a waterproof layer and making a drainage system.
S60, constructing a secondary lining of the first main tunnel to finish final reinforcement;
the secondary lining is mainly made of reinforced concrete and has the thickness of 35-45cm. The secondary lining is used for removing the decorative layer on one hand and resisting load and protecting the interior of the tunnel on the other hand. And (3) building the template by adopting a secondary lining trolley, and carrying out layered and left-right alternate symmetrical pouring when concrete is poured, wherein the maintenance period is not less than 14 days after the template is removed, so as to form the secondary lining.
S70, constructing other main tunnels, wherein the construction method of the other main tunnels is the same as that of the first main tunnel;
and S80, after all the main tunnels are constructed, constructing two auxiliary tunnels finally, wherein the auxiliary tunnels adopt a single-layer primary supporting structure or a double-layer primary supporting structure.
Because the main tunnel is constructed in advance, the constructed main tunnel is easily disturbed when adjacent tunnels are excavated, so that the secondary lining of the main tunnel is cracked, and the main tunnel is completely of a double-layer primary supporting structure. And because the auxiliary tunnel is constructed finally, the auxiliary tunnel is not disturbed after the construction is finished, and the cost can be saved by directly adopting the conventional single-layer primary supporting structure.
In the scheme of the application, the multi-arch tunnel structure comprises at least one main tunnel and two auxiliary tunnels, wherein the main tunnel is constructed in advance of the auxiliary tunnels, and each main tunnel comprises a first-layer primary support, a second-layer primary support and a secondary lining; the secondary primary support independent ring formation can effectively resist excavation disturbance during construction of adjacent tunnels, has the advantages of reinforcing support strength, isolating the influence of excavation of adjacent tunnels, and well protecting the secondary lining, thereby avoiding the situation that cracks and water seepage occur in the constructed secondary lining. The multi-arch tunnel mid-board is provided with a plurality of holes, the partition wall is provided with a plurality of arch-shaped tunnels, the partition wall is provided with a plurality of holes, the holes are arranged on the partition wall, the partition wall is provided with a plurality of arch-shaped tunnels, the holes are arranged on the partition wall, and the partition wall is provided with a plurality of arch-shaped tunnels.
Preferably, the step of performing waterproof treatment on the inner side of the second-layer primary support specifically includes:
and constructing a waterproof layer and a drainage pipeline on the inner side of the primary support of the second layer. And the drainage pipeline is used for collecting and discharging the surface seepage water. The waterproof layer can adopt geotextile and an LDPE waterproof layer, and water is blocked outside the secondary lining to serve as a first waterproof measure. The cast concrete of the secondary lining adopts waterproof concrete more than C25 for casting, a deformation joint of a tunnel body can be provided with a middle-buried rubber waterstop, a construction joint is provided with a bentonite rubber water bar with a grouting pipe, and a construction longitudinal joint between the side wall foundation and the secondary lining of the arch wall should also be provided with the rubber waterstop as a second waterproof measure.
As a preferred embodiment, the step of excavating the intermediate pilot tunnel of the first main tunnel and then pouring the intermediate wall concrete in sections to form the intermediate wall after excavation may specifically include:
spraying concrete on the hole wall of the excavated middle pilot tunnel in the excavating process, wherein the thickness of the concrete can be 3-5cm;
fitting the hole wall profile of the middle pilot tunnel, arranging a plurality of steel arches in the middle pilot tunnel at intervals, and connecting adjacent steel arches through connecting ribs; the steel arches are arranged at equal intervals according to the distance of 0.4-0.8 m.
A plurality of support frames are arranged on the ground of the middle pilot tunnel along the depth direction of the middle pilot tunnel, and the plurality of support frames are correspondingly connected with the plurality of steel arches one by one; wherein, the support frame and the steel arch center can be made of I-steel, and the support frame is used for supporting the steel arch center
Arranging a reinforcing mesh on the plurality of steel arch frames; the reinforcing mesh is used for further fixing the steel arch frame.
And finally, pouring intermediate wall concrete in the intermediate wall in a segmented manner in the intermediate pilot tunnel to form the intermediate wall.
As an optional implementation manner of the present invention, the step of excavating the tunnel portal of the first main tunnel may specifically include:
dividing a tunnel portal of a first main tunnel into a left portal and a right portal, excavating the left portal, arranging grouting small pipes at a left arch part for advanced pre-support, arranging left arch part steel frames in the tunnel, and connecting the left arch part steel frames with pre-buried steel frames in the intermediate wall; excavating a left tunnel portal 30-40 meters later, then excavating a right tunnel portal, arranging a small grouting pipe on a right arch part for advanced pre-support, and arranging a right arch part steel frame; and alternately excavating the left side hole and the right side hole until the tunnel hole of the whole main tunnel is excavated. The construction operation safety is provided by means of left-right alternate excavation and advanced pre-support.
Preferably, the step of erecting the steel frame on the top of the mid-wall includes: and erecting a profile steel frame on the wall top of the intermediate wall, connecting the profile steel frame with the steel frame embedded in the intermediate wall, and fixing the connection part in a welding or bolt locking mode. In order to fully connect the primary support of the first layer and the intermediate wall into a whole, the steel frame of the primary support of the first layer and the steel frame embedded in the intermediate wall are fixedly connected and integrally formed by spraying concrete.
As a preferred embodiment of the present invention, the construction method may further include: and numbering all the main tunnels in sequence from left to right or from right to left, and constructing the main tunnels in sequence according to the numbering. Through constructing main tunnel according to a certain direction in order, can make the main tunnel that is located in the middle receive once the disturbance, make the efficiency of construction higher simultaneously.
As an optional embodiment of the present invention, the step of constructing the secondary lining of the first main tunnel may specifically include:
s61, designing reinforcing steel bars according to the tunnel internal parameters of the first main tunnel, marking the annular main bar arrangement positions according to the designed reinforcing steel bar intervals, marking the longitudinal distribution bar installation positions on the positioning reinforcing steel bars, then binding the reinforcing steel bars in the range, and constructing lining reinforcing steel bars;
s62, building a template by adopting a secondary lining trolley, and placing the bottom surface of the secondary lining trolley on the surface of the concrete filled with the constructed inverted arch; adjusting the center line of the template to coincide with the center of the girder of the trolley, so that the trolley is in a good stress state in the concrete pouring process; the trolley is moved to the mold erecting position, is adjusted to the accurate position by the jack, and is positioned and retested until the accurate position is adjusted;
wherein, in order to avoid the trolley floating up when the side wall concrete is poured, a wooden support or a jack is additionally arranged on the top of the trolley. While checking whether the working window is in good condition. And designing the reserved settlement amount in the process of measuring the paying-off.
S63, when concrete is poured, the concrete is poured in a layered and left-right alternate symmetrical mode, and the vertical distance between the pipe orifice of the conveying hose and the pouring surface is controlled within two meters;
the cast concrete adopts layered, left-right alternate and symmetrical casting, the height difference of two sides is controlled within 1.8m, the vertical distance from the pipe orifice of the conveying hose to the casting surface is controlled within two meters, so as to prevent concrete segregation. The pouring process needs to be continuous, cold joints caused by stop time are avoided, and the cold joints are processed according to construction joints when the stop time exceeds one hour. When the concrete is poured 50cm below the operation window, dirt near the window is scraped, a release agent is coated, and putty is coated at the joint of the window and the panel to ensure tight combination without leakage of slurry. And when the tunnel lining is capped, selecting proper concrete slump, and performing pressure injection capping from a pouring opening of the arch part. The concrete is pumped one by one from the top-sealing opening, the concrete pump is continuously operated, the delivery pipe is straight, the turning is slow, the joint is tight, and the pipeline is lubricated before pumping. And (3) embedding plastic grouting pipes longitudinally at preset intervals during top lining, and performing grouting treatment after lining.
And S64, maintaining for not less than 14 days after the mold is removed, and forming the secondary lining.
The strength of the concrete after pouring is more than 8.0 MPa. Before form removal, the outer surface of the template can be washed by water, and after form removal, the surface of the concrete is sprayed by high-pressure water so as to reduce hydration heat, and the curing period is not less than 14 days, so that the first layer of secondary lining is formed.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (8)

1. A construction method of a double-layer preliminary bracing multi-arch tunnel structure, wherein the number of double arches of the multi-arch tunnel structure is more than or equal to 3, the multi-arch tunnel comprises 2 auxiliary tunnels, at least two intermediate walls and a main tunnel arranged between two adjacent intermediate walls, and the 2 auxiliary tunnels are respectively positioned at two sides of the multi-arch tunnel, and is characterized by comprising the following steps:
excavating a middle pilot tunnel of the first main tunnel, and pouring middle partition wall concrete in a segmented mode after excavation to form the middle partition wall;
excavating a tunnel portal of a first main tunnel;
constructing a first layer of primary support of a first main tunnel: the first layer of primary support is formed on the wall top of the intermediate wall in a concrete spraying mode, and is connected with the intermediate wall into a whole under the action of concrete; the first layer of primary support is used for forming a safe construction space during tunnel portal construction;
constructing a second layer of primary support of the first main tunnel: erecting a section steel frame to be attached to an annular structure of the first-layer primary support, and forming the second-layer primary support in a concrete spraying mode; the primary support of the second layer is independently formed into a ring in the tunnel;
performing waterproof treatment and drainage treatment on the inner side of the primary support of the second layer;
and (3) constructing a secondary lining of the first main tunnel to finish final reinforcement: after the lining reinforcing steel bars are built, a template is built by using a secondary lining trolley, concrete is poured to form the secondary lining, and the secondary lining is used for finally reinforcing and preventing water for the tunnel;
the step of constructing the secondary lining of the first main tunnel specifically comprises: s61, designing reinforcing steel bars according to the tunnel internal parameters of the first main tunnel, marking the arrangement positions of the circumferential main reinforcing steel bars according to the designed reinforcing steel bar intervals, marking the installation positions of the longitudinal distribution bars on the positioning reinforcing steel bars, then binding the reinforcing steel bars in the range, and constructing lining reinforcing steel bars;
s62, building a template by adopting a secondary lining trolley, and placing the bottom surface of the secondary lining trolley on the surface of the concrete filled with the constructed inverted arch; adjusting the center line of the template to coincide with the center of the girder of the trolley, so that the trolley is in a good stress state in the concrete pouring process; the trolley is moved to the mold erecting position, is adjusted to the accurate position by the jack, and is positioned and retested until the accurate position is adjusted;
s63, when concrete is poured, the concrete is poured in a layered and left-right alternate symmetrical mode, and the vertical distance between the pipe orifice of the conveying hose and the pouring surface is controlled within two meters;
s64, after the form is removed, maintaining for not less than 14 days to form the secondary lining;
constructing other main tunnels, wherein the construction method of the other main tunnels is the same as that of the first main tunnel;
and finally constructing two auxiliary tunnels after constructing all the main tunnels, wherein the auxiliary tunnels adopt single-layer primary supporting structures or double-layer primary supporting structures.
2. The construction method according to claim 1, wherein the step of performing waterproofing treatment on the inner side of the second-layer preliminary bracing specifically comprises:
and constructing a waterproof layer and a drainage system on the inner side of the primary support of the second layer, wherein the waterproof layer is made of geotextile and LDPE waterproof material.
3. The construction method according to claim 1, wherein the step of excavating the pilot tunnel of the first main tunnel and the step of casting the intermediate wall concrete in sections after excavating to form the intermediate wall specifically comprises:
spraying concrete to the hole wall of the excavated middle pilot hole in the excavating process;
fitting the hole wall profile of the middle pilot tunnel, arranging a plurality of steel arches in the middle pilot tunnel at intervals, and connecting adjacent steel arches through connecting ribs;
arranging a plurality of support frames on the ground of the middle pilot tunnel along the depth direction of the middle pilot tunnel, wherein the plurality of support frames are correspondingly connected with the plurality of steel arches one by one;
arranging a reinforcing mesh on the plurality of steel arch frames;
and casting middle partition wall concrete in the middle pilot tunnel in sections to form the middle partition wall.
4. The construction method according to claim 1, wherein the step of excavating the tunnel opening of the first main tunnel comprises:
dividing a tunnel portal of a first main tunnel into a left portal and a right portal, excavating the left portal, arranging grouting small pipes at a left arch part for advanced pre-support, arranging left arch part steel frames in the tunnel, and connecting the left arch part steel frames with pre-buried steel frames in the intermediate wall; excavating a left tunnel portal 30-40 meters later, then excavating a right tunnel portal, arranging a small grouting pipe on a right arch part for advanced pre-support, and arranging a right arch part steel frame; and alternately excavating the left side hole and the right side hole until the tunnel hole of the whole main tunnel is excavated.
5. The construction method according to claim 1, wherein the step of erecting the steel section frame on the top of the intermediate wall specifically comprises:
and erecting a profile steel frame on the wall top of the intermediate wall, connecting the profile steel frame with the steel frame embedded in the intermediate wall, and fixing the connection part in a welding or bolt locking mode.
6. The construction method according to any one of claims 1 to 5, further comprising:
and numbering all the main tunnels in sequence from left to right or from right to left, and constructing the main tunnels according to the numbering sequence.
7. The construction method according to any one of claims 1 to 5, wherein the secondary lining is formed of steel bars and concrete and is formed as a ring separately.
8. The construction method according to claim 7, wherein the thickness of the secondary lining is 35-45cm.
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