CN113338951B - Three-step roof-picking construction method for rapid tunnel intersection - Google Patents
Three-step roof-picking construction method for rapid tunnel intersection Download PDFInfo
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- 238000010276 construction Methods 0.000 title claims abstract description 86
- 230000003014 reinforcing effect Effects 0.000 claims abstract description 53
- 239000011435 rock Substances 0.000 claims abstract description 47
- 238000004364 calculation method Methods 0.000 claims abstract description 42
- 238000000034 method Methods 0.000 claims abstract description 29
- 238000009412 basement excavation Methods 0.000 claims abstract description 28
- 238000004088 simulation Methods 0.000 claims abstract description 12
- 229910000831 Steel Inorganic materials 0.000 claims description 57
- 239000010959 steel Substances 0.000 claims description 57
- 230000008569 process Effects 0.000 claims description 18
- 238000013461 design Methods 0.000 claims description 12
- 238000009434 installation Methods 0.000 claims description 11
- 239000002689 soil Substances 0.000 claims description 7
- 239000004567 concrete Substances 0.000 claims description 6
- 238000011900 installation process Methods 0.000 claims description 6
- 239000011378 shotcrete Substances 0.000 claims description 6
- 238000005507 spraying Methods 0.000 claims description 5
- 238000009933 burial Methods 0.000 claims description 4
- 230000001154 acute effect Effects 0.000 claims description 3
- 238000005422 blasting Methods 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 description 11
- 238000005259 measurement Methods 0.000 description 7
- 238000013102 re-test Methods 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
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- 238000005728 strengthening Methods 0.000 description 2
- 241001640558 Cotoneaster horizontalis Species 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 239000003351 stiffener Substances 0.000 description 1
- 238000012549 training Methods 0.000 description 1
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Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
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- E—FIXED CONSTRUCTIONS
- E21—EARTH 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
- E21D11/003—Linings or provisions thereon, specially adapted for traffic tunnels, e.g. with built-in cleaning devices
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- E—FIXED CONSTRUCTIONS
- E21—EARTH 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
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/14—Layout of tunnels or galleries; Constructional features of tunnels or galleries, not otherwise provided for, e.g. portals, day-light attenuation at tunnel openings
Abstract
The application discloses a three-step roof-picking construction method for a rapid tunnel intersection, which comprises the following steps: burying a distance between the crossing position of the transverse hole and the positive hole to establish a three-dimensional numerical calculation model for simulation calculation, and determining the main concentration position and the stress concentration position of surrounding rock deformation after the transverse hole is transferred into the positive hole to open and support; carrying out lithology identification on surrounding rocks in a range of the crossing position of the transverse hole and the positive hole, which is close to the top picking range; excavating a transverse hole; digging an arch-shaped reinforcing ring section after the transverse arch frame is installed and supported, and taking the arch-shaped reinforcing ring section as an initial supporting section of the main tunnel; installing an arched reinforcing ring, so that the arched reinforcing ring penetrates into the primary support section of the main tunnel; digging a step shed tunnel on the main tunnel; and (5) installing and supporting the step arch on the main tunnel after the main tunnel is excavated. The method solves the problems of complicated supporting form, increased excavation outline, long supporting time and increased construction risk in the construction of the tunnel intersection roof-picking in the related art.
Description
Technical Field
The application relates to the field of tunnel construction, in particular to a three-step roof-picking construction method for a rapid tunnel intersection.
Background
Along with the high-speed development of the long tunnel industry in China, the long tunnel is generally influenced by construction period and geological characteristics of the long tunnel, a working face of a main tunnel is increased by utilizing a transverse tunnel or an inclined shaft, the position of an intersection of the transverse tunnel and the main tunnel is often a more complex stressed section of a tunnel structure, safety and quality hidden dangers are easy to occur, the position of the intersection of the transverse tunnel and the main tunnel is supported by adopting a door-opening-shaped reinforcing ring, a shed tunnel arch frame is required to be erected while excavation is carried out in the subsequent excavation process, and a sleeve arch is required to be installed after roof-picking construction is completed, so that the supporting form is complicated in the construction of the roof-picking of the tunnel intersection in the related technology, the excavation contour is increased, the supporting time is long, and the construction risk is increased.
Aiming at the problems of complicated supporting form, increased excavation outline and long supporting time in the tunnel intersection roof-picking construction in the related technology, which result in increased construction risk, no effective solution is proposed at present.
Disclosure of Invention
The application mainly aims to provide a three-step roof-picking construction method for a rapid tunnel intersection, which aims to solve the problems of complicated support form, increased excavation outline, long support time and increased construction risk in the roof-picking construction of the tunnel intersection in the related technology.
In order to achieve the above purpose, the application provides a construction method for three-step roof picking at a rapid tunnel intersection, which comprises the following steps:
establishing a three-dimensional numerical calculation model for simulating and calculating the depth of burial at the crossing position of the transverse tunnel and the positive tunnel according to survey data, checking and calculating settlement, deformation and stress in the construction process through simulating the tunnel construction step, and determining the main concentration position and the stress concentration position of surrounding rock deformation after the transverse tunnel is transferred into the positive tunnel to open and support;
identifying lithology of surrounding rocks in a range of the crossing position of the horizontal hole and the positive hole, which is close to the top picking range, and determining the strength and lithology of the surrounding rocks at the position;
if the main deformation concentration position and the stress concentration position of surrounding rock after the transverse hole is transferred into the positive hole to open and support are the intersection position of the transverse hole and the positive hole, and the lithology of the surrounding rock in the range of the intersection position of the transverse hole and the positive hole, which is close to the top picking, is extremely hard rock, excavating according to the following steps:
excavating a transverse tunnel, and installing and supporting a transverse tunnel arch frame of the transverse tunnel in the excavating process;
when a transverse tunnel is excavated to the intersection position of the transverse tunnel and the positive tunnel, excavating an arch-shaped reinforcing ring section after the installation and the support of the arch frame of the transverse tunnel are finished, and taking the arch-shaped reinforcing ring section as an initial support section of the positive tunnel;
installing an arched reinforcing ring, so that the arched reinforcing ring penetrates into the primary support section of the main tunnel;
excavating a step shed tunnel on the main tunnel, and carrying out smooth blasting construction by adopting detonating cords;
and installing and supporting a step arch frame on the main tunnel after the main tunnel is excavated, wherein the first end of the step arch frame on the main tunnel is fixed on an arch reinforcing ring, and the second end of the step arch frame is fixed on the excavated surrounding rock.
Further, the arch strengthening ring is the arch structure, and a plurality of support brackets are installed along its circumference to arch strengthening ring upper end, support bracket upper end is fixed with the steel sheet that is used for being connected with the step bow member on the positive hole.
Further, the arch-shaped reinforcing ring consists of 3I 25a steel frames, and the adjacent steel frames are connected by longitudinal steel bars with the diameter of 22 mm;
in the installation process of the arch reinforcing ring, installing is carried out one by one, 3 arch frames are connected into a whole in the installation process, the stability of the arch frames is ensured, and Shi Zuosuo foot anchor pipes are timely arranged after the installation is finished, so that the arch frames are prevented from being unstable;
i25a steel columns are longitudinally arranged on a steel frame of the arched reinforcing ring according to the spacing between the step arches on the positive tunnel and serve as supporting brackets, and steel plates with the thickness of 20mm and the thickness of 30cm multiplied by 60cm are pre-welded on the upper parts of the supporting brackets so as to be connected with the step arches on the positive tunnel;
the gap is backfilled and compacted by adopting C25 sprayed concrete after the steel frame is installed;
6 phi 50 foot locking anchor pipes and system anchor rods are additionally arranged on each side of the steel frame of the arched reinforcing ring, and the stability of the steel frame is improved.
Further, the establishing a numerical calculation model specifically includes: according to the geometric dimensions of the transverse tunnel and the positive tunnel, the three-dimensional fine modeling is carried out on soil bodies, the transverse tunnel, the positive tunnel and the like in the calculation area by combining the calculation areas of the transverse tunnel and the positive tunnel, and the soil bodies and the supporting structures adopt entity units.
Further, before the cross hole arch frame is installed, the cross hole arch frame is processed and manufactured according to the cross hole and the positive hole skew angle and the cross hole design support parameter requirements;
if the oblique angle of the transverse tunnel and the positive tunnel is an acute angle, the transverse tunnel arches are arranged in a mode of deviating from the normal, the transverse tunnel arches on the long sides of the connection between the transverse tunnel and the positive tunnel are arranged according to the step distance of the normal arches, the distance between the transverse tunnel arches on the short sides is properly reduced, and the connection section between the transverse tunnel and the positive tunnel is smoothly transited, so that the direction orthogonality between the tunnel face of the excavation of the step shed tunnel on the positive tunnel and the line direction of the positive tunnel is ensured when the step shed tunnel on the positive tunnel is constructed.
Further, the simulation of the tunnel construction step includes:
excavating a transverse hole, supporting in time, and excavating to the intersection position of the transverse hole and the positive hole;
excavating and supporting a step shed tunnel on the top of the main tunnel, and integrally calculating deformation of the three-dimensional numerical calculation model in the X, Y, Z directions and vault stress at the moment;
excavating and supporting a step shed tunnel in the main tunnel, and integrally calculating deformation of the three-dimensional numerical calculation model in the X, Y, Z directions and vault stress at the moment;
excavating and supporting a main tunnel lower step shed tunnel, and integrally calculating deformation of the three-dimensional numerical calculation model in the directions X, Y, Z and vault stress at the moment;
and excavating a distance from the full section of the main tunnel in the size and mileage, supporting, and integrally calculating the deformation of the three-dimensional numerical calculation model in the directions of X, Y, Z and the vault stress at the moment.
Further, the method also comprises the following steps of:
after the installation and support of the arch centering of the upper step of the main tunnel are completed, firstly excavating a first upper step shed tunnel along the small mileage direction of the main tunnel by taking the upper step shed tunnel of the main tunnel as a starting point, and then excavating a second upper step shed tunnel along the large mileage direction of the main tunnel;
firstly, excavating a first middle step shed tunnel along the small mileage direction of a positive tunnel by taking the first upper step shed tunnel as a starting point, and then excavating a second middle step shed tunnel along the large mileage direction of the positive tunnel by taking the second upper step shed tunnel as a starting point;
the first middle step shed tunnel is used as a starting point to excavate the first lower step shed tunnel along the small mileage direction of the positive tunnel, and the second middle step shed tunnel is used as a starting point to excavate the second lower step shed tunnel along the large mileage direction of the positive tunnel.
Primary spraying is carried out by adopting 10cm concrete in the positive tunnel excavation, and the excavation footage is controlled according to III-level surrounding rock;
and (3) carrying out positive hole excavation supporting according to design supporting measures, wherein when the positive hole is excavated to the designed arch frame position, the main hole is installed by adopting I20I-steel to form an upper guide arch frame, the arch frame spacing is 1.0m, and the cross sections extend 3 steel frames to two sides respectively.
Furthermore, before the arch-shaped reinforcing ring is installed, the arch-shaped reinforcing ring and the step arch on the main tunnel are pre-spliced outside.
Further, the cross tunnel arch comprises 7 arch frames arranged at the position, close to the main tunnel, of the cross tunnel, and the arrangement length of the 7 arch frames is not less than 6m.
The construction method utilizes a three-dimensional numerical calculation model in the early stage, simulates the most unfavorable condition of the construction stage of the intersection position of a transverse tunnel and a positive tunnel through tunnel lithology, analyzes the influence degree of rock mass deformation on tunnel support under the condition of different construction stages through calculation, optimizes the reinforcing ring of the traditional portal construction in the construction process of a top-picking tunnel, optimizes the reinforcing ring into an arch reinforcing ring, reduces the overexcavation disturbance of the rock mass in the construction process of the tunnel, cancels a shed tunnel arch frame and a sleeve arch frame according to the characteristics of surrounding rocks, greatly improves the construction progress, accelerates the primary support of an inverted arch to form a ring after the construction of a step shed tunnel on the positive tunnel is completed, and ensures the tunnel construction safety. The problems of complicated supporting form, increased excavation outline, long supporting time and increased construction risk in the tunnel intersection roof-picking construction in the related art are solved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application, are incorporated in and constitute a part of this specification. The drawings and their description are illustrative of the application and are not to be construed as unduly limiting the application. In the drawings:
FIG. 1 is a schematic diagram of a structure according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a hole construction in accordance with an embodiment of the present application;
FIG. 3 is a schematic view of an arcuate stiffener ring according to an embodiment of the present application;
FIG. 4 is a schematic diagram of a three-dimensional numerical calculation model in accordance with an embodiment of the present application;
the system comprises a main tunnel, a first lower step shed tunnel, a first middle step shed tunnel, a first upper step shed tunnel, an 8 arched reinforcing ring, an 81I25a steel frame, 82 supporting brackets, 83 steel plates and 9 main tunnel upper step arches, wherein the main tunnel is provided with the first upper step shed tunnel, the second lower step shed tunnel, the second middle step shed tunnel, the first lower step shed tunnel, the first middle step shed tunnel, the first upper step shed tunnel, the 8 arched reinforcing ring, the 81I25a steel frame, the 82 supporting brackets, the 83 steel plates and the 9 main tunnel upper step arches.
Detailed Description
In order that those skilled in the art will better understand the present application, a technical solution in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, shall fall within the scope of the present application.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present application and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe the embodiments of the application herein.
In the present application, the azimuth or positional relationship indicated by the terms "upper", "lower", "inner", and the like are based on the azimuth or positional relationship shown in the drawings. These terms are only used to better describe the present application and its embodiments and are not intended to limit the scope of the indicated devices, elements or components to the particular orientations or to configure and operate in the particular orientations.
Also, some of the terms described above may be used to indicate other meanings in addition to orientation or positional relationships, for example, the term "upper" may also be used to indicate some sort of attachment or connection in some cases. The specific meaning of these terms in the present application will be understood by those of ordinary skill in the art according to the specific circumstances.
Furthermore, the terms "disposed," "configured," "connected," "secured," and the like are to be construed broadly. For example, "connected" may be in a fixed connection, a removable connection, or a unitary construction; may be a mechanical connection, or an electrical connection; may be directly connected, or indirectly connected through intervening media, or may be in internal communication between two devices, elements, or components. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.
In addition, the term "plurality" shall mean two as well as more than two.
It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The application will be described in detail below with reference to the drawings in connection with embodiments.
As shown in fig. 1 to 4, the embodiment of the application provides a construction method for three-step roof picking at a rapid tunnel intersection, which comprises the following steps:
establishing a three-dimensional numerical calculation model for simulating and calculating the depth of burial at the crossing position of the transverse tunnel and the positive tunnel according to survey data, checking and calculating settlement, deformation and stress in the construction process through simulating the tunnel construction step, and determining the main concentration position and the stress concentration position of surrounding rock deformation after the transverse tunnel is transferred into the positive tunnel to open and support;
identifying lithology of surrounding rocks in a range of the crossing position of the horizontal hole and the positive hole, which is close to the top picking range, and determining the strength and lithology of the surrounding rocks at the position;
if the main deformation concentration position and the stress concentration position of surrounding rock after the transverse hole is transferred into the positive hole to open and support are the intersection position of the transverse hole and the positive hole, and the lithology of the surrounding rock in the range of the intersection position of the transverse hole and the positive hole, which is close to the top picking, is extremely hard rock, excavating according to the following steps:
excavating a transverse tunnel, mounting and supporting the transverse tunnel arch frame of the transverse tunnel in the excavating process, and processing and manufacturing the transverse tunnel arch frame according to the inclined angle between the transverse tunnel and the positive tunnel and the design and supporting parameter requirement of the transverse tunnel before the transverse tunnel arch frame is mounted;
if the oblique angle of the transverse tunnel and the positive tunnel is an acute angle, arranging transverse tunnel arches in a mode of deviating from the normal, arranging transverse tunnel arches on the long side of the connection between the transverse tunnel and the positive tunnel according to the step distance of the normal arches, properly reducing the distance between the transverse tunnel arches on the short side, enabling the connection section between the transverse tunnel and the positive tunnel to smoothly transition, ensuring that the excavation face of the step shed tunnel 1 on the positive tunnel is orthogonal with the line direction of the positive tunnel when the step shed tunnel 1 on the positive tunnel is constructed, and facilitating the excavation of the positive tunnel;
when a transverse tunnel is excavated to the intersection position of the transverse tunnel and the positive tunnel, the section of the arched reinforcing ring 8 is excavated after the installation and the support of the arch centering of the transverse tunnel are finished, and the section of the arched reinforcing ring 8 is used as the primary support section of the positive tunnel;
installing an arched reinforcing ring 8, and enabling the arched reinforcing ring 8 to extend into the primary support section of the main tunnel;
excavating the step shed tunnel 1 on the main tunnel, and carrying out smooth blasting construction by adopting detonating cords;
and after the excavation of the main tunnel upper step shed tunnel 1 is completed, installing and supporting a main tunnel upper step arch 9, wherein the first end of the main tunnel upper step arch 9 is fixed on the arch reinforcing ring 8, and the second end is fixed on the excavated surrounding rock.
The construction method is suitable for the construction of transferring a transverse tunnel into a positive tunnel and picking a roof, in the embodiment, a three-dimensional numerical calculation model is established by using MidsaGTS, simulation is carried out on the least adverse condition of the construction stage of the intersection position of the transverse tunnel and the positive tunnel through tunnel lithology, the influence degree of rock mass deformation on tunnel support under the condition of different construction stages is calculated and analyzed, and corresponding measures are taken and reinforced aiming at places with larger influence positions in the construction process.
And carrying out construction preparation before construction, wherein the construction preparation comprises inner industry preparation and outer industry preparation, wherein the inner industry preparation comprises that design drawings are checked, after the design of the center line, the elevation and the structure size of the positive hole and the transverse hole is checked, the construction retest and measurement work are completed, retest results meet the requirements, and the construction retest and the measurement work are approved by a supervision unit, and tunnel monitoring measurement implementation rules are compiled and implemented. The construction report and examination procedure is perfected, the examination construction drawing is carefully read before the construction is carried out on the front tunnel, the coordinates and elevation of the front tunnel are accurately calculated, the structural size is calculated, the construction safety guarantee measures and the emergency plan are formulated, the technical mating is carried out on the construction team, and the front-post training is carried out on the participants.
The field preparation comprises mechanical equipment preparation, personnel preparation, material supply preparation and measurement control preparation, wherein the measurement control preparation is the weight of the whole construction process, before the cross-tunnel construction enters the main tunnel, the engineering department measurement group and the engineering department frame team measurement group retest the wire points, retest the tunnel elevation and the line center line, and then carry out the top picking construction of the main tunnel after retest is qualified.
The calculation is carried out by establishing a three-dimensional numerical calculation model to carry out simulation calculation to simulate the tunnel construction working condition, the three-dimensional grid is adopted to carry out simulation calculation about the depth of burial at the intersection position of the transverse tunnel and the positive tunnel by about 210m, and the concrete content of the simulation calculation mainly comprises the following aspects:
(1) The numerical simulation process strictly follows the sequence of engineering construction, and tunnel support is excavated from an initial soil body-a transverse tunnel is turned to a positive tunnel to pick a roof; and for the simulation of tunnel construction, the construction sequence of tunnel excavation and support is embodied.
(2) And considering the construction influence of the rock mass on the tunnel in the process of turning the transverse tunnel into the main tunnel, picking, pushing and supporting, and checking the settlement and the stress in the construction process.
And calculating the domain according to the geometric dimensions of the transverse tunnel and the positive tunnel and combining the transverse tunnel and the positive tunnel. The rock mass of the calculation model has the length of 80m in the front-back direction, 53.6m in the left-right direction and 36.6m in the up-down height. The three-dimensional fine modeling is carried out on soil bodies, transverse holes, positive holes and the like in the calculation area, and the soil bodies and supporting structures all adopt entity units.
According to the calculation model size, the calculation time and the calculation accuracy are comprehensively considered, and the total number of the units is 36953. And (5) establishing a rock mass-structure calculation model.
The simulation of the tunnel construction step comprises:
excavating a transverse hole, supporting in time, and excavating to the intersection position of the transverse hole and the positive hole;
excavating and supporting a step shed tunnel on the top of the main tunnel, and integrally calculating deformation of the three-dimensional numerical calculation model in the X, Y, Z directions and vault stress at the moment;
excavating and supporting a step shed tunnel in the main tunnel, and integrally calculating deformation of the three-dimensional numerical calculation model in the X, Y, Z directions and vault stress at the moment;
excavating and supporting a main tunnel lower step shed tunnel, and integrally calculating deformation of the three-dimensional numerical calculation model in the directions X, Y, Z and vault stress at the moment;
and excavating a distance from the full section of the main tunnel in the size and mileage, supporting, and integrally calculating the deformation of the three-dimensional numerical calculation model in the directions of X, Y, Z and the vault stress at the moment.
The conclusion of the simulation calculation is:
the three-dimensional grid calculation is simulated by considering the most unfavorable condition, the action of an anchor rod is not considered in the three-dimensional grid rock mass reinforcement measure, the method of full-section construction is adopted for excavating the right and left positive holes after entering the positive holes, three steps are adopted for excavating and supporting the top, and the result is displayed after the three-dimensional grid simulation and calculation: after the transverse tunnel is transferred into the positive tunnel to open and support, surrounding rock deformation is mainly concentrated at the crossing position of the transverse tunnel and the positive tunnel, and stress concentration is easy to occur; the method is characterized in that a full-section method is adopted for the left and right excavation of the main hole, the deformation of surrounding rock at the crossing position of the transverse hole and the positive hole is still increased, each 30m of the left and right excavation is carried out, when the positive hole is accumulated for 60m, the deformation of the surrounding rock is gradually reduced by less than 1mmm, the observation and the application of a construction method are paid attention to in the excavation process, and the reserved deformation is increased; when the variation stress of surrounding rock is accumulated for 80m along with the excavation of a positive hole, the maximum stress of 19.54Mpa of the surrounding rock is within the compressive strength range of C25 sprayed concrete, the stress of a top-selected intersection is gradually increased to 6.2Mpa, and the intersection position needs to be reinforced and supported, so that the construction safety is ensured.
The lithology of the surrounding rock in the range close to the top picking range at the crossing position of the transverse tunnel and the positive tunnel is extremely hard rock, so that the rock body has good strength, and a sleeve arch and a canopy frame structure in the related technology can be canceled when the step canopy tunnel 1 on the positive tunnel is excavated. The sprayed concrete in the construction process adopts glass fiber to increase the strength of the sprayed concrete, and simultaneously, a tension shell type anchor rod is additionally arranged to ensure the stability of surrounding rock.
The tunnel is simulated through a three-dimensional model to carry out checking calculation on the most unfavorable position, construction risks in the jacking process are known in advance, original design optimization construction is carried out, when the tunnel is assisted to excavate a tunnel and is close to a positive tunnel, the elevation of a construction arch is gradually raised, the elevation gradient of a vault is controlled to be within 30%, the actual gradient is 8%, the elevation is 50cm, an I20a primary support steel frame is adopted to enter the positive tunnel from the intersection of the positive tunnel and the assisted tunnel, the cross section positive tunnel is excavated, 10.8m is excavated, the elevation gradient is 8%, 0.6m arch reinforcing ring 8 is arranged at the intersection of the assisted tunnel and the positive tunnel, and 3I 25a assisted tunnel steel frames are arranged in the arch reinforcing ring 8. The positive hole is designed as III-level surrounding rock, IVb parameter support is adopted, I20 steel frame support is adopted, and the distance is 1.0m; the plateau mouth cross hole is designed into a level II surrounding rock, and a double-lane level III surrounding rock spray anchor is adopted to support the integral lining.
As shown in fig. 3, the arch-shaped reinforcing ring 8 has an arch structure, a plurality of supporting brackets 82 are mounted on the upper end of the arch-shaped reinforcing ring 8 along the circumferential direction thereof, and a steel plate 83 for connecting with the step arch 9 on the main tunnel is fixed on the upper end of the supporting brackets 82.
Further, the arch-shaped reinforcing ring 8 consists of 3I 25a steel frames 81, wherein the adjacent steel frames are connected by longitudinal steel bars with the diameter of 22mm, and the distance between the longitudinal steel bars is 1m;
meanwhile, the primary support section of the positive hole is well controlled, in the installation process of the arch-shaped reinforcing ring 8, in order to ensure that the supporting of the positive hole is provided with powerful support, 3 auxiliary tunnel section steel is firstly constructed, the 3 arch frames are installed one by one, in the installation process, the 3 arch frames are connected into a whole, the stability of the arch frames is ensured, and the anchor pipes of Shi Zuosuo feet are timely used after the installation is completed, so that the instability of the arch frames is prevented;
i25a steel columns are longitudinally arranged on a steel frame of the arched reinforcing ring 8 according to the spacing of the step arch 9 on the positive tunnel to serve as supporting brackets 82, and steel plates 83 with the thickness of 20mm and the thickness of 30cm multiplied by 60cm are pre-welded on the upper parts of the supporting brackets to be connected with the step arch 9 on the positive tunnel;
the gap is backfilled and compacted by adopting C25 sprayed concrete after the steel frame is installed;
6 phi 50 foot locking anchor pipes and system anchor rods are additionally arranged on each side of the steel frame of the arched reinforcing ring 8, and the stability of the steel frame is improved.
As shown in fig. 2, the method further comprises the following steps:
after the installation and support of the main tunnel upper step arch 9 are completed, the main tunnel upper step shed tunnel 1 is used as a starting point to excavate the first upper step shed tunnel 7 along the main tunnel small mileage direction, and then the second upper step shed tunnel 4 along the main tunnel large mileage direction;
firstly, excavating a first middle step shed tunnel 6 along the small mileage direction of a positive tunnel by taking a first upper step shed tunnel 7 as a starting point, and then excavating a second middle step shed tunnel 3 along the large mileage direction of the positive tunnel by taking a second upper step shed tunnel 4 as a starting point;
firstly, the second middle step shed tunnel 3 is used as a starting point to excavate the first lower step shed tunnel 5 along the small mileage direction of the positive tunnel, and then the second middle step shed tunnel 3 is used as a starting point to excavate the second lower step shed tunnel 2 along the large mileage direction of the positive tunnel.
Primary spraying is carried out by adopting 10cm concrete in the positive tunnel excavation, and the excavation footage is controlled according to III-level surrounding rock;
and (3) carrying out positive hole excavation supporting according to design supporting measures, wherein when the positive hole is excavated to the designed arch frame position, the main hole is installed by adopting I20I-steel to form an upper guide arch frame, the arch frame spacing is 1.0m, and the cross sections extend 3 steel frames to two sides respectively.
After the construction of the reinforcing ring is completed, one side of the steel frame is provided with a steel backing plate falling foot on the reinforcing ring of the auxiliary tunnel intersection, the steel backing plate is connected with a steel plate 83 pre-welded with the primary support steel frame by adopting 8.8-level bolts, the steel plate 83 is a 2cm steel plate 83, the other side of the steel plate is supported by adopting a concrete pad or on a hard rock surface, and 2 phi 50 foot locking anchor pipes with the length of 4m are respectively applied at the sections and the arch feet of the steel frame. Backfilling the front position of the reinforcing ring to be heightened according to 8% gradient, excavating a shed tunnel in the direction of a tunnel positive tunnel, wherein the net height of the shed tunnel is 5m, the width of the shed tunnel is 4m, and excavating adopts 10cm concrete for primary spraying, and the excavation footage is controlled according to III-level surrounding rocks. And (3) carrying out positive hole excavation supporting according to design supporting measures, wherein when the positive hole is excavated to the designed arch frame position, the main hole is installed by adopting I20I-steel to form an upper guide arch frame, the arch frame spacing is 1.0m, and the cross sections extend 3 steel frames to two sides respectively. The system anchor rod adopts a shell-expanding anchor rod, the arch space is adjusted to be 1 multiplied by 1.5m from 1.5 multiplied by 1.6m of the original design, and the side wall space is adjusted to be 1 multiplied by 1.5m from 1.2 multiplied by 1.5m of the original design. After shed tunnel construction is completed, a main tunnel arch frame is installed, zhang Keshi anchor rods are installed and mixed in a spraying mode, arch frame foot locking anchor pipes are additionally arranged, grouting cement grouting proportion is 1:2.5-3, and grouting quality is guaranteed; setting settlement observation targets in time, wherein the maximum settlement rate v=1.15 mm/d of DK110+850 vault at the intersection of a cross tunnel and a positive tunnel, the accumulated settlement is 9mm after the large and small mileage is excavated, the maximum convergence rate v=1.29 mm/d of DK110+850 perimeter convergence is accumulated: 12.1mm, all meet the standard requirements.
The problem that the hole arch frame and the reinforcing ring are not corresponding to each other due to the reserved connecting steel plate 83 may occur in the construction process, and the problem is caused by the fact that errors exist in arch frame processing and in installation of the arch frame on the construction site, therefore, before the arch reinforcing ring 8 is installed, the arch reinforcing ring 8 and the hole upper step arch frame 9 are pre-spliced outside, the transverse arch frame comprises 7 arch frames arranged at positions, close to the main hole, of the transverse arch frame, and the arrangement length is not less than 6m.
The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (8)
1. The three-step roof-picking construction method for the rapid tunnel intersection is characterized by comprising the following steps of:
establishing a three-dimensional numerical calculation model for simulating and calculating the depth of burial at the crossing position of the transverse tunnel and the positive tunnel according to survey data, checking and calculating settlement, deformation and stress in the construction process through simulating the tunnel construction step, and determining the main concentration position and the stress concentration position of surrounding rock deformation after the transverse tunnel is transferred into the positive tunnel to open and support;
identifying lithology of surrounding rocks in a range of the crossing position of the horizontal hole and the positive hole, which is close to the top picking range, and determining the strength and lithology of the surrounding rocks at the position;
if the main deformation concentration position and the stress concentration position of surrounding rock after the transverse hole is transferred into the positive hole to open and support are the intersection position of the transverse hole and the positive hole, and the lithology of the surrounding rock in the range of the intersection position of the transverse hole and the positive hole, which is close to the top picking, is extremely hard rock, excavating according to the following steps:
excavating a transverse tunnel, and installing and supporting a transverse tunnel arch frame of the transverse tunnel in the excavating process;
when a transverse tunnel is excavated to the intersection position of the transverse tunnel and the positive tunnel, excavating an arch-shaped reinforcing ring section after the installation and the support of the arch frame of the transverse tunnel are finished, and taking the arch-shaped reinforcing ring section as an initial support section of the positive tunnel;
installing an arched reinforcing ring, so that the arched reinforcing ring penetrates into the primary support section of the main tunnel;
the arch-shaped reinforcing ring is of an arch structure, a plurality of supporting brackets are arranged at the upper end of the arch-shaped reinforcing ring along the circumferential direction of the arch-shaped reinforcing ring, and a steel plate used for being connected with a step arch frame on a positive hole is fixed at the upper end of each supporting bracket;
the arch-shaped reinforcing ring consists of 3I 25a steel frames, and the adjacent steel frames are connected by longitudinal steel bars with the diameter of 22 mm;
excavating a step shed tunnel on the main tunnel, and carrying out smooth blasting construction by adopting detonating cords;
installing and supporting a step arch frame on the main tunnel after the main tunnel is excavated, wherein the first end of the step arch frame on the main tunnel is fixed on an arch-shaped reinforcing ring, and the second end of the step arch frame is fixed on an excavated surrounding rock;
the method also comprises the following steps of:
after the installation and support of the arch centering of the upper step of the main tunnel are completed, firstly excavating a first upper step shed tunnel along the small mileage direction of the main tunnel by taking the upper step shed tunnel of the main tunnel as a starting point, and then excavating a second upper step shed tunnel along the large mileage direction of the main tunnel;
firstly, excavating a first middle step shed tunnel along the small mileage direction of a positive tunnel by taking the first upper step shed tunnel as a starting point, and then excavating a second middle step shed tunnel along the large mileage direction of the positive tunnel by taking the second upper step shed tunnel as a starting point;
the first middle step shed tunnel is used as a starting point to excavate the first lower step shed tunnel along the small mileage direction of the positive tunnel, and the second middle step shed tunnel is used as a starting point to excavate the second lower step shed tunnel along the large mileage direction of the positive tunnel.
2. The construction method for three-step roof picking at the rapid tunnel intersection according to claim 1, wherein in the installation process of the arch-shaped reinforcing ring, the arch frames are installed one by one, 3 arch frames are connected into a whole in the installation process, the stability of the arch frames is ensured, and a Shi Zuosuo foot anchor pipe is timely arranged after the installation is completed, so that the instability of the arch frames is prevented;
i25a steel columns are longitudinally arranged on a steel frame of the arched reinforcing ring according to the spacing between the step arches on the positive tunnel and serve as supporting brackets, and steel plates with the thickness of 20mm and the thickness of 30cm multiplied by 60cm are pre-welded on the upper parts of the supporting brackets so as to be connected with the step arches on the positive tunnel;
backfilling the gaps with C25 sprayed concrete after the steel frame is installed;
6 phi 50 foot locking anchor pipes and system anchor rods are additionally arranged on each side of the steel frame of the arched reinforcing ring, and the stability of the steel frame is improved.
3. The rapid tunnel intersection three-step roof-picking construction method according to claim 1, wherein the building of the three-dimensional numerical calculation model is specifically: according to the geometric dimensions of the transverse tunnel and the positive tunnel, combining the calculation domains of the transverse tunnel and the positive tunnel, carrying out three-dimensional fine modeling on the soil body, the transverse tunnel and the positive tunnel in the calculation region, wherein the soil body and the supporting structure adopt entity units.
4. The construction method for three-step roof picking at the intersection of a rapid tunnel according to claim 3, wherein before the installation of the cross tunnel arch, the cross tunnel arch is manufactured according to the cross tunnel and the positive tunnel skew angle and the cross tunnel design support parameter requirement;
if the oblique angle of the transverse tunnel and the positive tunnel is an acute angle, the transverse tunnel arches are arranged in a mode of deviating from the normal, the transverse tunnel arches on the long sides of the connection between the transverse tunnel and the positive tunnel are arranged according to the step distance of the normal arches, the distance between the transverse tunnel arches on the short sides is properly reduced, and the connection section between the transverse tunnel and the positive tunnel is smoothly transited, so that the direction orthogonality between the tunnel face of the excavation of the step shed tunnel on the positive tunnel and the line direction of the positive tunnel is ensured when the step shed tunnel on the positive tunnel is constructed.
5. The method for three-step roof picking construction at a rapid tunnel intersection according to claim 4, wherein the simulation of the tunnel construction step comprises:
excavating a transverse hole, supporting in time, and excavating to the intersection position of the transverse hole and the positive hole;
excavating and supporting a step shed tunnel on the top of the main tunnel, and integrally calculating deformation of the three-dimensional numerical calculation model in the X, Y, Z directions and vault stress at the moment;
excavating and supporting a step shed tunnel in the main tunnel, and integrally calculating deformation of the three-dimensional numerical calculation model in the X, Y, Z directions and vault stress at the moment;
excavating and supporting a main tunnel lower step shed tunnel, and integrally calculating deformation of the three-dimensional numerical calculation model in the directions X, Y, Z and vault stress at the moment;
and excavating a distance from the full section of the main tunnel in the size and mileage, supporting, and integrally calculating the deformation of the three-dimensional numerical calculation model in the directions of X, Y, Z and the vault stress at the moment.
6. The rapid tunnel intersection three-step roof-picking construction method according to claim 5, wherein 10cm of concrete is adopted for primary spraying in the positive tunnel excavation, and excavation footage is controlled according to III-level surrounding rocks;
and (3) carrying out positive hole excavation supporting according to design supporting measures, wherein when the positive hole is excavated to the designed arch frame position, the main hole is installed by adopting I20I-steel to form an upper guide arch frame, the arch frame spacing is 1.0m, and the cross sections extend 3 steel frames to two sides respectively.
7. The method for three-step roof construction at a rapid tunnel intersection according to claim 6, wherein the arch-shaped reinforcing ring is pre-spliced with the step arch on the main tunnel on the outside before being installed.
8. The method for three-step roof picking construction at a rapid tunnel intersection according to claim 7, wherein the cross tunnel arch comprises 7 arch frames arranged at the position of the cross tunnel adjacent to the main tunnel, and the arrangement length is not less than 6m.
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