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 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 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 after all the main tunnels are constructed, constructing two auxiliary tunnels finally, wherein the auxiliary tunnels adopt single-layer primary support structures or double-layer primary support 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 middle partition wall concrete in sections after excavation to form the middle partition wall specifically includes:
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 arch frames at intervals in the middle pilot tunnel, and connecting adjacent steel arch frames through connecting ribs;
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;
arranging a reinforcing mesh on the plurality of steel arch frames;
and pouring middle partition wall concrete in the middle guide hole 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 a small grouting guide pipe at a left arch part for advanced pre-support, arranging a left arch part steel frame in the tunnel, and connecting the left arch part steel frame with an embedded steel frame in the middle partition 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 profile steel frame on the top of the mid-wall specifically 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.
Preferably, the construction method further comprises:
and numbering all the main tunnels in sequence from left to right or from right to left, and installing the numbering sequence to construct the main tunnels.
Preferably, the secondary lining is constructed of steel reinforcement and concrete and is looped separately.
Preferably, the thickness of the secondary lining is 35-45 cm.
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-layer primary support independent ring can effectively resist excavation disturbance during construction of adjacent tunnels, has the functions of reinforcing support strength and isolating excavation influence of the adjacent tunnels, and plays a good role in protecting the secondary lining, thereby avoiding the situation that cracks and water seepage appear in the constructed secondary lining. Meanwhile, waterproof and drainage measures are more conveniently implemented between the primary support of the second layer and the secondary lining, so that the defect of difficulty in drainage of the traditional multi-arch tunnel can be overcome.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to 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 the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, the descriptions related to "first", "second", etc. in the present invention are 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 such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory 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 double-decker 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 can be three-arch, four-arch, five-arch or even six-arch. The present embodiment will be described with reference to the drawings by way of example of four arches.
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 support 110, a second layer of primary support 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 disposed 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 of 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 reinforcing support strength, and has the effect of isolating excavation influence 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 functions of reinforcing support strength and isolating excavation influence of the adjacent tunnels, and has a good protection effect on the secondary lining 130, so that 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 multi-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.
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 mold concrete of the secondary lining is cast by waterproof concrete above C25, a deformation joint of a tunnel body can be provided with a buried rubber water stop, 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 is also provided with the rubber water stop 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 from 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 on both sides of the multi-arch tunnel, and after the main tunnel is constructed, 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. The auxiliary tunnel is constructed finally, so that the auxiliary tunnel is not disturbed after 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 section steel frame and a shotcrete structure, one end of the single-layered preliminary bracing 210 is erected on the top of the intermediate wall 300, the section steel frame of the single-layered preliminary bracing 210 is connected to a steel frame embedded in the intermediate wall 300 and is integrated with the intermediate wall 300 by shotcrete; the single-layered lining 220 is disposed inside the single-layered preliminary bracing 210.
In an embodiment of the present invention, the side surface of the intermediate wall 300 is an inwardly concave arc-shaped surface, and the side surface of the intermediate wall 300 is connected to the arc-shaped inner side surface of the first preliminary bracing to form a semicircular inner wall surface. 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. 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 support frames are connected with the steel arches in a one-to-one correspondence manner; and then reinforcing steel meshes are arranged on the plurality of steel arch frames, and concrete for the intermediate wall 300 is poured in the intermediate pilot tunnel in sections 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. The method is characterized in that smooth blasting large-section excavation is adopted, support means such as anchors, spraying, nets, steel arches, advanced ducts, advanced pipe sheds and the like are used, a through middle pilot tunnel is excavated firstly, and middle partition wall concrete is poured.
S20, excavating a tunnel portal of the first main tunnel;
when the construction is carried out by adopting the pilot tunnel-main tunnel method, the waterproof material of the top of the middle partition wall is laid, the concrete with the same mark number of the middle partition wall is backfilled, a long pipe shed is arranged for grouting, then the upper arch and the temporary support of the right tunnel are excavated, and the deformation observation of the surrounding rock 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.
And 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 mode; the primary support of the second layer forms a ring independently in the tunnel;
in order to construct a second-layer primary support, the profile steel frames can be firstly constructed on the inner side of the first-layer primary support, a plurality of profile steel frames are welded into a ring-shaped structure, and concrete is sprayed to the profile steel frames to form the second-layer primary support which is independently formed into a 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.
And 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 a thickness of 35-45 cm. 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 performing 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 that the secondary lining is formed.
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 single-layer primary support structures or double-layer primary support structures.
Because the main tunnel is constructed in advance, the constructed main tunnel is easy to disturb 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 support 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-layer primary support independent ring can effectively resist excavation disturbance during construction of adjacent tunnels, has the functions of reinforcing support strength and isolating excavation influence of the adjacent tunnels, and plays a good role in protecting the secondary lining, thereby avoiding the situation that cracks and water seepage appear 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.
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 the surface seepage water and then 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 mold concrete of the secondary lining is cast by waterproof concrete above C25, a deformation joint of a tunnel body can be provided with a buried rubber water stop, 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 is also provided with the rubber water stop as a second waterproof measure.
As a preferred embodiment, the step of excavating the intermediate pilot tunnel of the first main tunnel and pouring intermediate wall concrete in sections after excavation to form the intermediate wall may specifically include:
spraying concrete to the hole wall of the excavated middle pilot tunnel in the excavation process, wherein the thickness of the concrete can be 3-5 cm;
fitting the hole wall profile of the middle pilot tunnel, arranging a plurality of steel arch frames at intervals in the middle pilot tunnel, and connecting adjacent steel arch frames 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 guide hole in a segmented mode 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 a small grouting guide pipe at a left arch part for advanced pre-support, arranging a left arch part steel frame in the tunnel, and connecting the left arch part steel frame with an embedded steel frame in the middle partition 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. The construction operation safety is provided by alternately excavating left and right and carrying out advanced pre-supporting.
Preferably, the step of erecting the profile steel frame on the top of the mid-wall specifically 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 installing the numbering sequence to construct the main tunnels. 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 steel bars according to the tunnel internal parameters of the first main tunnel, marking the annular main bar arrangement positions according to the designed steel bar spacing, marking the longitudinal distribution bar installation positions on the positioning steel bars, then binding the steel bars in the range, and constructing lining steel bars;
s62, building a template by adopting a secondary lining trolley, and placing the bottom surface of the secondary lining trolley on the concrete surface 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 runs to the position of the vertical mold, is adjusted to the accurate position by a 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 the design of the reserved settlement amount needs to be considered when the paying-off is measured.
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 are avoided, and the construction joints are processed 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 and prevent slurry leakage. 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, removing the mold, and maintaining for at least 14 days to form 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.