CN114086993A - Supporting system and excavation method for oversized section tunnel - Google Patents
Supporting system and excavation method for oversized section tunnel Download PDFInfo
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- CN114086993A CN114086993A CN202111442316.2A CN202111442316A CN114086993A CN 114086993 A CN114086993 A CN 114086993A CN 202111442316 A CN202111442316 A CN 202111442316A CN 114086993 A CN114086993 A CN 114086993A
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/14—Lining predominantly with metal
- E21D11/18—Arch members ; Network made of arch members ; Ring elements; Polygon elements; Polygon elements inside arches
- E21D11/183—Supporting means for arch members, not provided for in E21D11/22
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
- E21D11/105—Transport or application of concrete specially adapted for the lining of tunnels or galleries ; Backfilling the space between main building element and the surrounding rock, e.g. with concrete
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D20/00—Setting anchoring-bolts
- E21D20/003—Machines for drilling anchor holes and setting anchor bolts
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Abstract
The invention provides a supporting system of a tunnel with an oversized section. The advanced support comprises a pipe shed and a small advanced grouting conduit, and the primary support comprises sprayed concrete and steel supports, and further comprises a system anchor rod and an anchor cable which are arranged on the periphery of the tunnel. The invention also provides an excavation method of the tunnel with the oversized section, which is a step-by-step multi-step excavation method.
Description
Technical Field
The invention relates to the field of tunnel engineering, in particular to a supporting system and an excavation method for a tunnel with an oversized section.
Background
Since 21, as the Chinese traffic network is gradually developed, more and more complicated tunnel projects are required. The tunnel section is larger and larger under the restriction of a plurality of objective conditions such as construction environment and the like, for example, the maximum excavation width of the exit of the tunnel No. 2 Wumengshan of six-touch railway reaches 28.42m, and the maximum excavation area is 354.30m2The maximum excavation span of the great wall station of Badaling of the Beijing Zhang high-speed railway is 32.7m, and the maximum excavation area reaches 494.4m2. The tunnel excavation face is enlarged, the operation space can be provided for mechanical equipment, the process circulation is simplified, the tunnel face self-stability is reduced, and the construction risk degree is increased. Therefore, the selection of a construction method with strong applicability, safety and high efficiency is very critical.
At present, researches on construction methods of large-span tunnels have achieved a lot of results, and most of the researches are focused on large-span double-track and three-track railway tunnels and shallow-buried highway tunnels, and the working methods mainly adopt a double-side wall method and a CRD method. But exceeds 400m for excavated area2The ultra-large section tunnel can not adopt full section excavation, and must adopt subsection excavation to form a tunnel. When the subsection excavation is adopted, on one hand, due to different construction sequences, the stability of surrounding rocks is different; on the other hand, the more the branches are, the more temporary supports are provided for stabilizing the cavern during construction, which affects the working efficiency of the mechanical equipment. Meanwhile, before the secondary lining construction, the temporary support must be removed, if the once removal section is too long, instability, deformation, over-limit or cracking and collapse of the cavern can be caused, and if the once removal section is too short, the secondary lining construction quality and progress must be influenced.
In view of this, the research aiming at the supporting system and the excavation method of the tunnel with the oversized section is urgent, and the research has very important significance for promoting the development of the tunnel construction technology.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, provides a supporting system and an excavation method of a tunnel with an oversized section, aims to improve the excavation efficiency and the structural safety of the tunnel with the oversized section, and solves part of problems in the prior art.
The invention is realized by the following steps:
the invention provides a supporting system of a tunnel with an oversized section.
Further, the support system in super large section tunnel includes advance support, advance support includes pipe canopy and advance slip casting little pipe, pipe canopy and advance slip casting little pipe all along tunnel top circumference interval distribution.
Further, the support system in super large section tunnel includes preliminary bracing, preliminary bracing is including locating steel shotcrete, shotcrete in the tunnel, locating peripheral system stock, the anchor rope in tunnel.
Further, the steel support comprises a plurality of steel frames, the sprayed concrete comprises primary sprayed concrete sprayed on the outer side of the steel frames and secondary sprayed concrete sprayed on the inner side of the steel frames, and a waterproof layer is arranged between the secondary lining and the secondary sprayed concrete.
Furthermore, each steel frame is distributed at intervals along the excavation direction of the tunnel, two adjacent steel frames are connected through a plurality of longitudinal connecting reinforcing steel bars, and each longitudinal connecting reinforcing steel bar is distributed at intervals along the circumferential direction of the tunnel.
Furthermore, the anchor cable is anchored according to a certain distance according to the stress of the primary support of the tunnel and the requirement of rigidity of each section of the primary support under the condition of the overall structure.
Furthermore, the supporting system of the tunnel with the oversized section further comprises a secondary lining, secondary lining parameters are calculated and determined according to geological conditions of the tunnel, and a waterproof layer is arranged between the secondary lining and the re-sprayed concrete.
The invention also provides an excavation method of the tunnel with the oversized section, wherein the excavation method is a step-by-step multi-step excavation method, and the tunnel is excavated step-by-step.
Furthermore, according to the stress of the primary support of the tunnel, the rigidity requirement of each section of the primary support under the condition of the whole structure is calculated, anchor cables are arranged at two ends and in the middle of the primary support at a certain interval for anchoring, and the section of the excavated single-span tunnel is converted into a section of a continuous beam structure anchored at multiple points.
Furthermore, the step-by-step multi-step excavation method comprises the steps of dividing the excavation surface of the tunnel into a plurality of steps along the vertical direction, adopting two side slope excavation and arranging temporary supports for the steps positioned at the top, namely excavating the middle area firstly and then excavating the two side areas; and selecting a construction sequence for the steps below the top step according to the number of the blocks, adopting two-step left-right excavation when the number of the blocks is two, adopting a reserved core soil method when the number of the blocks is more than or equal to three, excavating the two side areas firstly, excavating the middle area finally, and excavating the inverted arch part of the tunnel once.
Furthermore, the section tunnel adopts step-by-step multi-step excavation, the tunnel excavation face is divided into a first step, a second step, a third step and a fourth step along the vertical direction, and the specific steps are as follows:
p1, constructing a tunnel roof advance support, constructing an advance long pipe shed, constructing an advance grouting small pipe after completing the construction of the pipe shed, performing advance grouting, and reinforcing a tunnel roof stratum;
p2, excavating a first step middle area, excavating side slopes on two sides of the first step middle area, constructing a primary support and an anchor rope of the first step middle area, constructing a temporary support on the side slopes on two sides, specifically, spraying concrete initially, erecting a steel frame, constructing steel frame longitudinal connecting steel bars, spraying concrete again, arranging a prestressed anchor rod on a tunnel top, constructing an anchor rope in the first step middle area, spraying concrete again to a designed thickness, excavating the first step right side area after the first step middle area operation is completed, arranging a certain distance between the excavation surface of the first step right side area and the excavation surface of the first step middle area, arranging a certain distance between the excavation surface of the first step right side area and the excavation surface of the first step right side area, constructing the primary support and the anchor rope of the first step right side area, excavating the first step left side area after the first step right area is completed, arranging a certain distance between the excavation surface of the first step left side area and the excavation surface of the first step right area, the primary support operation mode of the left area of the first step is the same as that of the right area of the first step, primary support and anchor cables of the left area of the first step are constructed, the left area of the first step is completed, and therefore excavation of the first step is completed;
p3, excavating a second step in advance by adopting a reserved core soil method, excavating a right side area of the second step, excavating a middle area of the second step, and timely constructing a primary support and an anchor cable, wherein a certain distance is reserved between the excavating surface of the left side area of the second step and the excavating surface of the right side area of the second step, and a certain distance is reserved between the excavating surface of the middle area of the second step and the excavating surface of the left side area of the second step;
the excavation modes of the P4 and the third step are the same as those of the second step, a reserved core soil method is adopted, the excavation sequence is a third step right side area, a third step left side area and a third step middle area in sequence, primary supports and anchor cables are applied in time, a certain distance is arranged between the excavation surface of the third step right side area and the excavation surface of the second step middle area, a certain distance is arranged between the excavation surface of the third step left side area and the excavation surface of the third step right side area, a certain distance is arranged between the excavation surface of the third step middle area and the excavation surface of the third step left side area, and the third step excavation is finished;
p5, finishing fourth step excavation at one time and constructing primary support;
p6, pouring an inverted arch, filling the inverted arch, and finishing the pouring of the whole ring lining after the primary support is converged.
The invention has the following beneficial effects:
1. the invention provides a support system of an oversized section tunnel, which adopts steel support, sprayed concrete, a system anchor rod and an anchor cable for temporary support. The anchor cables are anchored at two ends of the primary support, so that the deformation of the two ends of the primary support in each block excavation section can be reduced; the anchor cable is arranged in the middle of primary support, can play the effect that reduces anchor rock supporting body and spouts concrete structure span, and the primary support of whole tunnel section warp when restraining other piecemeal excavations.
2. Because the anchor cables are arranged at the two ends of the primary support of each block, the deformation of the primary support is reduced, the anchor cables can replace the inner supports to control the deformation of the surrounding rock under the condition of controllable deformation, the construction procedures are reduced, the operation space in the tunnel is enlarged, the construction freedom degree is high, the condition of large-scale mechanical construction is met, and the construction efficiency is high.
3. The invention provides a step-by-step multi-step excavation method for an oversized section tunnel matched with an innovative primary support. The excavation method has the following remarkable advantages: the step height and the step width of the tunnel are larger than those of the conventional CRD and double-side-wall pit guiding method, so that the mechanized construction of the tunnel is facilitated, the operation efficiency is improved, and the surrounding rock disturbance is reduced.
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 drawings without creative efforts.
Fig. 1 is a schematic diagram of a single-span structure to a multi-span structure provided in an embodiment of the present invention;
fig. 2 is a schematic diagram of a tunneling method according to an embodiment of the present invention (solution one);
fig. 3 is a schematic diagram of a tunneling method according to an embodiment of the present invention (scheme two);
fig. 4 is a schematic view of a slope structure provided in the embodiment of the present invention;
fig. 5 is a schematic view of a forepoling provided by an embodiment of the present invention;
FIG. 6 is a schematic view of a steel frame position provided in an embodiment of the present invention;
fig. 7 is a schematic view of a steel frame connection provided in an embodiment of the present invention.
Detailed Description
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.
Referring to fig. 1 to 7, an embodiment of the present invention provides a supporting system for an ultra-large section tunnel and an excavation method. The supporting system of the oversized cross-section tunnel comprises an advance support, a primary support and a secondary lining. The excavation method of the tunnel with the ultra-large section is a step-by-step multi-step excavation method.
As shown in fig. 5, the advance support comprises a pipe shed 3 and small advance grouting pipes 9, wherein the pipe shed 3 and the small advance grouting pipes 9 are circumferentially distributed at intervals along the tunnel roof.
The primary support comprises a steel support arranged in the tunnel, sprayed concrete 5, a first anchor rod 1 arranged on the periphery of the tunnel and an anchor cable 2. As shown in fig. 6, the steel support includes a plurality of steel frames 4, and the sprayed concrete 5 includes a first sprayed concrete 17 sprayed on the outer side of the steel frame 4 and a second sprayed concrete 18 sprayed on the inner side of the steel frame 4. As shown in fig. 7, each of the steel frames 4 is spaced apart from each other along the extending direction of the tunnel, two adjacent steel frames 4 are connected to each other through a plurality of longitudinal connecting steel bars 19, each of the longitudinal connecting steel bars 19 is spaced apart from each other along the circumferential direction of the tunnel, the longitudinal distance between two adjacent steel frames 4 is a, and a is selected according to the actual requirements of construction. The first anchor rods 1 are distributed at intervals along the circumferential profile of the tunnel, the anchor cables 2 are arranged along the middle and end portions of each region in the circumferential direction of the tunnel, the longitudinal distance of the anchor cables 2 is consistent with that of the steel frame 4, and the bottom of the tunnel is provided with a foot locking anchor rod 6.
The parameters of the secondary lining 7 are determined by calculation according to the geological conditions of the tunnel, and a waterproof layer 10 is arranged between the secondary lining 7 and the re-sprayed concrete 18.
The method for excavating the tunnel with the ultra-large section is a step-by-step excavation method, the step-by-step excavation method is divided into a plurality of steps along the vertical direction of the tunnel excavation surface, and each step above the inverted arch of the tunnel comprises a plurality of step areas excavated in a subsection mode. As shown in fig. 2, in a first tunnel construction method scheme, the first tunnel construction method is divided into a first step, a second step, a third step and a fourth step, the first step, the second step, the third step and the fourth step are sequentially constructed, and the first step comprises a first step middle area I, a first step right side area II and a first step left side area III; the second step comprises a right side area of the second step, a left side area of the second step, and a middle area of the second step; the third step comprises a third step right side area (c), a third step left side area (b) and a third step middle area (c); the fourth step includes region r.
According to the excavation method of the tunnel with the ultra-large section, anchor rope anchoring points are added at two ends and in the middle of a primary support in each excavation range, primary support deformation is reduced, and anchors can be used for replacing internal temporary supports when the primary support deformation meets requirements; when the primary support is deformed after the anchor cables are arranged, temporary support in the tunnel can be arranged, the section tunnel adopts a step-by-step excavation method, and the height of the step and the width of the blocks need to meet the space requirement of tunnel mechanized construction.
According to the anchor cable arrangement method, the rigidity requirement of each section of primary support under the condition of the whole structure is calculated according to the stress of the primary support of the tunnel, and anchor cables are arranged at certain intervals for anchoring. The anchor cable tension force calculation method is characterized in that a surrounding rock plastic region is analyzed by adopting an elastic-plastic finite element method, the relaxation collapse load of the plastic region is used as the calculation load of the anchor cable, the anchor cable can bear the confining pressure of the excavation subsection, the safety coefficient is not less than 2.0, and meanwhile, the anchoring region of the anchor cable is out of the plastic region.
The step-by-step multi-step excavation method comprises the steps of dividing the excavation surface of the tunnel into a plurality of steps along the vertical direction, excavating the middle area of the steps at the top, and excavating the areas at two sides; and selecting a construction sequence for the steps below the top step according to the number of the blocks, adopting two-step left-right excavation when the number of the blocks is two, adopting a reserved core soil method when the number of the blocks is more than or equal to three, excavating the two side areas firstly, excavating the middle area finally, and excavating the inverted arch part of the tunnel once.
The section tunnel adopts step-by-step multi-step excavation, the tunnel excavation face is divided into first step, second step, third step, fourth step along vertical direction, and concrete steps are:
p1, as shown in figure 5, constructing a tunnel roof advance support, constructing an advance long pipe shed 3, constructing an advance grouting small pipe 9 after the pipe shed is constructed, performing advance grouting, and reinforcing a tunnel roof stratum;
p2, excavating a first step middle area, determining the excavation size according to the operation space of mechanical equipment, excavating side slopes 8 at two sides of the first step middle area, constructing a first step middle area, primary supporting and anchor cables, constructing temporary supporting on the side slopes 8 at two sides, specifically, primarily spraying concrete 17, erecting a steel frame 4, constructing steel frame longitudinal connecting steel bars 19, spraying concrete 18 again, constructing a steel bar net and concrete on the surfaces of the side slopes 8, spraying concrete 18 again, constructing a prestressed anchor rod (a first anchor rod 1) on the top of a tunnel, constructing anchor cables 2 in the first step middle area, keeping the longitudinal distance between the anchor cables and the steel frame consistent, spraying concrete 18 again to the designed thickness, excavating the first step right side area after the operation of the first step middle area is completed, excavating the first step right side area secondly excavating surface to the first step middle area firstly excavating surface with a certain distance, the method comprises the following steps of (1) constructing a first step right area, a first step middle area, a first step left area, a first step right area, a first step middle area, a first step right area, a first step left area, a second step right area, a second step left area, a second step right area, a first step middle area, a second step right area, a second step left area, a second step right area, a third step right area, a fourth step left area, a fourth step right area, a fourth step left area, a fourth step right area, a fourth step right area, a fourth step right area, a fourth and a fourth area, a fourth step right area, a fourth step, a fourth step, a fourth and a fourth, a fourth step right area, a fourth and a fourth step, a fourth;
p3, excavating a second step by adopting a reserved core soil method, excavating a right side area of the second step in advance, wherein the excavation width needs to meet the requirement of a mechanical device operation space, a certain distance is reserved between an excavation surface of the right side area of the second step and a left side area of the first step, performing primary support and an anchor cable on the right side area of the second step, similarly, completing a left side area of the second step, excavating a middle area of the second step, and performing the primary support and the anchor cable in time, a certain distance is reserved between the excavation surface of the left side area of the second step and the excavation surface of the right side area of the second step, and a certain distance is reserved between the excavation surface of the middle area of the second step and the excavation surface of the left side area of the second step, so that the second step is excavated;
p4, the excavation mode of a third step is consistent with that of a second step, a core soil reservation method is adopted, the excavation sequence is that a right side area of the third step is seventh, a left side area of the third step is seventh, and a middle area of the third step is ninth, the excavation span is determined according to the operation space of mechanical equipment, an initial support and an anchor cable are timely constructed, a certain distance is arranged from an excavation surface of the right side area of the third step to a middle area of the second step, a certain distance is arranged from the excavation surface of the left side area of the third step to the excavation surface of the right side area of the third step, a certain distance is arranged from the excavation surface of the middle area of the third step to the excavation surface of the left side area of the third step, and a certain distance is arranged from the excavation surface of the middle area of the third step to the excavation surface of the left side area of the third step, so that the third step is completed;
p5, finishing excavation of a fourth step at one time and constructing primary supports (a steel frame 4 and sprayed concrete 5);
p6, pouring an inverted arch, filling the inverted arch, and finishing the pouring of the whole ring lining (pouring of a secondary lining 7) after the primary support is converged.
The side slope 8 is provided with a temporary support, the temporary support comprises a steel bar mesh 14, sprayed concrete 5 and a plurality of second anchor rods 15, as shown in fig. 4, the steel bar mesh 14 and the sprayed concrete 5 are arranged on the surface of the side slope 8, and each second anchor rod 15 is arranged in the side slope 8.
Aiming at the problems in the prior art, the invention provides a supporting system and an excavation method suitable for a tunnel with an oversized section, and the supporting system and the excavation method mainly solve the following key technical problems:
(1) large-section tunnel supporting structure
Aiming at meeting the requirements of mechanical construction block and large-section tunnel primary support rigidity, the primary support of a system anchor rod, concrete spraying, a steel frame and an anchor cable is provided, the anchor cable is arranged on the primary support of the block excavation, a single-span structure 11 in the prior art is converted into a continuous beam structure (namely a multi-span structure 12, as shown in figure 1) anchored at multiple points, an internal temporary support is omitted, and the problems of low operation efficiency of mechanical equipment, large primary support deformation and influence on tunnel construction safety in the large-section tunnel excavation by a double-side wall method and a CRD method are solved.
(2) Large-section tunnel excavation method
The method for multi-step excavation by steps is provided by combining the rigidity and deformation characteristics provided by the primary support of the system anchor rod, the concrete spraying, the steel frame and the anchor rope and the requirements of mechanized construction, so that the tunnel construction efficiency is improved, the tunnel surrounding rock exposure time is reduced, the disturbance of the surrounding stratum is reduced, the stress state of the tunnel structure is improved, and the construction safety is improved.
The invention provides a combined primary support structure of a system anchor rod, concrete spraying, a steel frame and an anchor cable, wherein the anchor cable is arranged along the contour of a tunnel according to the rigidity requirements of a step-by-step excavation section and a whole-ring primary support;
the invention provides a multi-step excavation method by steps, wherein the height of the steps and the width of the blocks need to meet the space requirement of mechanical construction of a tunnel;
when the primary support can meet the deformation requirement of block construction, particularly when the deformation of the primary support ends of the blocks meets the requirement, the temporary support structure in the tunnel can be cancelled by the step-by-step excavation method, slope connection with stable slopes can be arranged among the blocks, and the slope can be provided with corresponding shotcrete supports;
the primary support is deformed after the anchor cable is arranged, particularly when the deformation of the primary support end is large, the temporary support in the tunnel can be arranged, and the form of the temporary support and the like are determined according to the requirements of deformation control;
in the step-by-step excavation method, the middle part of the upper step can be excavated firstly and then the two sides can be excavated to meet the space requirement of the construction equipment; selecting a construction sequence according to the number of the blocks below the upper step, adopting two-step left-right excavation (such as a tunnel construction method scheme II in figure 3) when the blocks are 2 blocks, adopting a reserved core soil method when the number of the blocks is more than or equal to 3 blocks, excavating two sides firstly, and finally excavating the middle (such as a tunnel construction method scheme I in figure 2); and excavating the inverted arch part of the tunnel once.
The full-section excavation method and the CRD method have the problems of insufficient supporting strength for surrounding rocks, low operation efficiency of mechanical equipment, difficult dismantling of temporary supports and the like in the excavation of the tunnel with the ultra-large section. The invention provides a supporting system and an excavation method suitable for a tunnel with an oversized section, which are remarkably characterized in that: the primary support adopts steel support, sprayed concrete, system anchor rods and anchor cables, and the tunnel is excavated in steps.
The concrete construction steps are as follows:
s1: according to the rigidity requirement of the integral primary support of the tunnel, parameters such as the length of a system anchor rod, the thickness of sprayed concrete, the distance between steel frames and the like are formulated, wherein the system anchor rod, the sprayed concrete, the steel frames and the like need to meet the requirements of surrounding rock stability and support construction space under the condition of stepwise excavation of small sections, and the safety construction requirement of the anchor cable can be guaranteed.
S2: according to the stress of the primary support of the tunnel, the rigidity requirement of each section of the primary support under the condition of the whole structure is calculated, anchor cables are arranged at certain intervals for anchoring, the original one-span structure is changed into a continuous beam structure with multi-point anchoring, the structural rigidity is increased, and the deformation of the primary support is reduced. The anchor cable tension force calculation method is characterized in that a surrounding rock plastic region is analyzed by adopting an elastic-plastic finite element method, the relaxation collapse load of the plastic region is used as the calculation load of the anchor cable, the anchor cable can bear the confining pressure of the excavation subsection, the safety coefficient is not less than 2.0, and meanwhile, the anchoring region of the anchor cable is out of the plastic region.
S3: under the protection of the primary support, the tunnel with the oversized section can be excavated by steps in multiple steps. The steps are as follows:
p1: constructing a tunnel roof advance support (as shown in fig. 5), excavating a middle area of a first step, and determining the excavation size according to the operation space of mechanical equipment. And (3) carrying out slope excavation on two sides of the area, wherein the excavation slope rate is 1: n (the slope rate is determined according to the self-stability capability of surrounding rocks), constructing the area, carrying out primary support and anchor cables, and simultaneously carrying out temporary support on the side slopes on the two sides. After the middle area is excavated to a certain depth, the right area of the first step is excavated, the distance between the area and the face (excavation face) of the area is d1, the area and the initial support and the anchor cable are applied, after the area is completed, the left area of the first step is excavated, the distance between the area and the excavation face is d1, and the initial support and the anchor cable are completed. And finishing the excavation of the first step.
P2: and the second step excavation adopts a reserved core soil method, the right side area is excavated in advance, and the excavation width meets the requirement of the operation space of mechanical equipment. And d2, constructing primary supports and anchor cables in the area (r). Similarly, the left area of the second step, the middle area, and the excavation are sequentially finished, and primary support and anchor cables are timely constructed. The distance between the areas from region (c) to region (c) and from region (c) to region (c) is generally d 1. And finishing the excavation of the second step.
P3: excavating the third step and the second step by adopting a reserved core soil method, wherein the excavating sequence is (c) → ((c) → nin) > sequentially, the excavating span is determined according to the working space of mechanical equipment, and an initial support and an anchor cable are timely constructed. The distance between the area (c) and the area (c) is d2, and the distance between the area (b) and the area (c) and the area (b) is d 1. And finishing the excavation of the third step.
P4: and (4) excavating and primary supporting of the fourth step (area (R) at one time.
P5: and pouring an inverted arch, filling the inverted arch, and finishing the whole-ring lining pouring after the primary support is converged.
The first tunneling method scheme (as shown in fig. 2) provided in the embodiment of the present invention is specifically described above; fig. 3 is a diagram illustrating a second tunnel construction method scheme according to an embodiment of the present invention, in which an excavation area of the second tunnel construction method scheme is divided into areas
Region(s)
Region(s)
Region(s)
Region(s)
Other embodiments such as the first scheme of the tunnel construction method are not described herein again. Fig. 4 is a schematic view of a slope structure provided in an embodiment of the present invention, where fig. 4 shows: tunnel excavation contour line 13, reinforcing mesh 14, sprayed concrete 5, second anchor rod 15 and branch excavation line 16. FIG. 6 is a schematic view of a steel frame position provided by an embodiment of the invention, and FIG. 6Shown therein are: steel frame 4, secondary lining 7, waterproof layer 10, primary concrete 17, and secondary concrete 18. Fig. 7 is a schematic connection diagram of a steel frame according to an embodiment of the present invention, where: the steel frame 4, the longitudinal connecting steel bars 19, the inner side 20 of the steel frame of the section steel and the corners of the steel bars are welded on the flange plate 21 on the inner side of the steel frame.
Fig. 2-3 are schematic cross-sectional views of a supporting system and an excavation method of an ultra-large section tunnel, wherein the supporting system comprises a forepoling, a primary supporting and a secondary lining, the method has the obvious advantages that the primary supporting adopts a combined structure of steel support, sprayed concrete, a system anchor rod and an anchor rope, anchor rope anchoring points are added at two ends and in the middle of the primary supporting in each excavation range, the deformation of the primary supporting is reduced, and when the deformation of the primary supporting meets the requirement, the anchor rope can be used for replacing an internal temporary support. Fig. 4 is a schematic diagram of a slope structure, the slope rate is determined according to the self-stability capability of surrounding rocks, the slope is provided with temporary supports, and reinforcing mesh, sprayed concrete and mortar anchor rods are adopted. Fig. 5 is a schematic diagram of a forepoling, which comprises a tunnel long pipe shed 3 and a small forepoling conduit 9.
The specific embodiment of the invention is as follows:
s1: construction of forepoling (as shown in figure 5). Arranging an advanced long pipe shed 3, wherein the long pipe shed adopts a hot-rolled seamless steel flower pipe with the outer diameter of D1Wall thickness delta1Single root length L1Distance d in circumferential direction3Angle of inclination theta1The length of the front and back lap joints is not less than L2. After the construction of the pipe shed is finished, an advanced grouting small conduit 9 is arranged, and the parameters of the common advanced small conduit are as follows: outer diameter of D2Wall thickness delta2Single root length L3Distance d in circumferential direction3The length of the front and back lap joints is not less than L4And performing advanced grouting to reinforce the tunnel top stratum. The advance support construction range is theta on the left side and the right side of the tunnel top2And (4) degree.
S2: and (4) excavating the middle area (i) of the first step, wherein the excavating width is B1, the height is H1, and two sides are opened to form slope excavation, as shown in figure 4. The excavation slope rate of the two sides is 1: n, the slope rate is determined according to the self-stability capability of the surrounding rock, and a temporary support is constructed, wherein the thickness of the sprayed concrete in the temporary support is phi1By outside diameter D3Mesh reinforcement, interval a1×a1The anchor rod adopts an outer diameter D4Mortar anchor rod, length L5A distance a2×a2. After the region is excavated, spraying phi2Thick concrete, steel frames 4 are erected with a longitudinal distance a, and steel frame longitudinal connecting steel bars are constructed, as shown in fig. 7. Spraying phi again3Thick concrete, applying reinforcing bar net, and spraying again4Thick concrete, a shell-expanding type prestressed anchor rod (first anchor rod 1) is arranged, and the outer diameter of the anchor rod is D5Length L of6A distance a3×b3(circle x vertical), anchor cable 2 in construction area (r), anchor cable length L7And the longitudinal distance is consistent with the steel frame, and the concrete is sprayed again to the designed thickness. At this point, the operation of region i is completed. Excavating a right area of the first step, wherein the excavating width is B2Height H2The distance between the area from the area II to the area I and the excavation surface is preferably d1After the area is excavated, spraying phi2Thick concrete, steel frames 4 are erected with a longitudinal distance a, and steel frame longitudinal connecting steel bars are constructed, as shown in fig. 7. Spraying phi again3Thick concrete, applying reinforcing bar net, and spraying again4Thick concrete, a shell-expanding type prestressed anchor rod (first anchor rod 1) is arranged, and the outer diameter of the anchor rod is D5Length L of anchor rod6A distance a3×b3(circled x longitudinal), anchor cable 2 in construction area (ii), anchor cable length L7And the longitudinal distance is consistent with the steel frame, and the concrete is sprayed again to the designed thickness. Excavating the left area of the first step, wherein the distance from the excavating surface of the area to the excavating surface of the area is preferably d1The size of the excavated space and the primary support operation mode are consistent with those of the region II. And finishing the excavation of the first step.
P3: the second step excavation adopts a reserved core soil method, the right side area is excavated in advance, and the excavation width is B3(B3B/3, B is the second step excavation span), and the requirement of mechanical equipment operating space needs to be satisfied simultaneously. The distance from the area (r) to the area (c) is about d2And constructing an area (iv) for primary support and anchor cable. Similarly, the left area of the second step, the middle area, and the excavation are sequentially finished, and primary support and anchor cables are timely constructed. Region (c) to region (c)Interval between area and excavated surface is d1. And finishing the excavation of the second step.
P4: the excavation mode of the third step is consistent with that of the second step, a core soil reservation method is adopted, the excavation sequence is (c) → ((r) → nini), the excavation span is determined according to the operation space of mechanical equipment, and initial support and anchor cables are timely constructed. Distance between region (c) and region (c) about d2The distance between the excavated surfaces of the area ((r) to area (c) and the area (nini) to area (r)) is generally d1. And finishing the excavation of the third step.
P5: and (5) finishing excavation of the fourth step at one time and constructing primary support.
P6: and pouring an inverted arch, filling the inverted arch, and finishing the whole-ring lining pouring after the primary support is converged.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. The utility model provides a support system in super large section tunnel which characterized in that: the supporting system comprises an advance support, a primary support and a secondary lining.
2. The support system of the ultra-large section tunnel of claim 1, wherein: the advanced support comprises a pipe shed and an advanced grouting small pipe, wherein the pipe shed and the advanced grouting small pipe are distributed at intervals along the circumferential direction of the tunnel top.
3. The support system of the ultra-large section tunnel of claim 1, wherein: the primary support comprises steel supports arranged in the tunnel, sprayed concrete, system anchor rods arranged on the periphery of the tunnel and anchor cables.
4. The support system of the ultra-large section tunnel of claim 1, wherein: and calculating and determining the secondary lining parameters according to the geological conditions of the tunnel.
5. The support system of the ultra-large section tunnel of claim 3, wherein: the steel support comprises a plurality of steel frames, the sprayed concrete comprises primary sprayed concrete sprayed on the outer side of the steel frames and secondary sprayed concrete sprayed on the inner side of the steel frames, and a waterproof layer is arranged between the secondary lining and the secondary sprayed concrete.
6. The support system of the ultra-large section tunnel of claim 5, wherein: the steel frames are distributed at intervals along the excavation direction of the tunnel, two adjacent steel frames are connected through a plurality of longitudinal connecting steel bars, and the longitudinal connecting steel bars are distributed at intervals along the circumferential direction of the tunnel.
7. The excavation method of the tunnel with the oversized section is characterized by comprising the following steps: the excavation method is a step-by-step multi-step excavation method, and the tunnel is excavated step-by-step.
8. The excavation method of the ultra-large section tunnel according to claim 7, wherein: according to the stress of the primary support of the tunnel, the rigidity requirement of each section of the primary support under the condition of the whole structure is calculated, anchor cables are arranged at the two ends and the middle of the primary support at certain intervals for anchoring, and the excavated single-span tunnel section is converted into a multi-point anchored continuous beam structure section.
9. The excavation method of the ultra-large section tunnel according to claim 7, wherein: excavating the steps at the top by adopting two side slope-laying excavation and arranging temporary supports, namely excavating the middle area firstly and then excavating the two side areas; and selecting a construction sequence for the steps below the top step according to the number of the blocks, adopting two-step left-right excavation when the number of the blocks is two, adopting a reserved core soil method when the number of the blocks is more than or equal to three, excavating the two side areas firstly, excavating the middle area finally, and excavating the inverted arch part of the tunnel once.
10. The excavation method of the ultra-large section tunnel according to claim 7, wherein: the section tunnel adopts step-by-step multi-step excavation, the tunnel excavation face is divided into first step, second step, third step, fourth step along vertical direction, and concrete steps are:
p1, constructing a tunnel roof advance support, constructing an advance long pipe shed, constructing an advance grouting small pipe after completing the construction of the pipe shed, performing advance grouting, and reinforcing a tunnel roof stratum;
p2, excavating a first step middle area, excavating side slopes on two sides of the first step middle area, constructing a primary support and an anchor rope of the first step middle area, constructing a temporary support on the side slopes on two sides, specifically, spraying concrete initially, erecting a steel frame, constructing steel frame longitudinal connecting steel bars, spraying concrete again, arranging a prestressed anchor rod on a tunnel top, constructing an anchor rope in the first step middle area, spraying concrete again to a designed thickness, excavating the first step right side area after the first step middle area operation is completed, arranging a certain distance between the excavation surface of the first step right side area and the excavation surface of the first step middle area, arranging a certain distance between the excavation surface of the first step right side area and the excavation surface of the first step right side area, constructing the primary support and the anchor rope of the first step right side area, excavating the first step left side area after the first step right area is completed, arranging a certain distance between the excavation surface of the first step left side area and the excavation surface of the first step right area, the primary support operation mode of the left area of the first step is the same as that of the right area of the first step, primary support and anchor cables of the left area of the first step are constructed, the left area of the first step is completed, and therefore excavation of the first step is completed;
p3, excavating a second step in advance by adopting a reserved core soil method, excavating a right side area of the second step, excavating a middle area of the second step, and timely constructing a primary support and an anchor cable, wherein a certain distance is reserved between the excavating surface of the left side area of the second step and the excavating surface of the right side area of the second step, and a certain distance is reserved between the excavating surface of the middle area of the second step and the excavating surface of the left side area of the second step;
the excavation modes of the P4 and the third step are the same as those of the second step, a reserved core soil method is adopted, the excavation sequence is a third step right side area, a third step left side area and a third step middle area in sequence, primary supports and anchor cables are applied in time, a certain distance is arranged between the excavation surface of the third step right side area and the excavation surface of the second step middle area, a certain distance is arranged between the excavation surface of the third step left side area and the excavation surface of the third step right side area, a certain distance is arranged between the excavation surface of the third step middle area and the excavation surface of the third step left side area, and the third step excavation is finished;
p5, finishing fourth step excavation at one time and constructing primary support;
p6, pouring an inverted arch, filling the inverted arch, and finishing the pouring of the whole ring lining after the primary support is converged.
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