CN115182751A - Construction method of shallow-buried large-span tunnel supporting structure and supporting structure - Google Patents
Construction method of shallow-buried large-span tunnel supporting structure and supporting structure Download PDFInfo
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- 230000008093 supporting effect Effects 0.000 title claims abstract description 89
- 238000010276 construction Methods 0.000 title claims abstract description 29
- 239000002689 soil Substances 0.000 claims abstract description 101
- 229910000831 Steel Inorganic materials 0.000 claims description 58
- 239000010959 steel Substances 0.000 claims description 58
- 238000000034 method Methods 0.000 claims description 16
- 238000005553 drilling Methods 0.000 claims description 9
- 239000011435 rock Substances 0.000 claims description 9
- 239000000945 filler Substances 0.000 claims description 5
- 239000002002 slurry Substances 0.000 claims description 5
- 238000009412 basement excavation Methods 0.000 description 12
- 239000007788 liquid Substances 0.000 description 5
- 238000001125 extrusion Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 238000007569 slipcasting Methods 0.000 description 3
- 238000007711 solidification Methods 0.000 description 3
- 230000008023 solidification Effects 0.000 description 3
- 238000005259 measurement Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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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
- E21D20/02—Setting anchoring-bolts with provisions for grouting
- E21D20/021—Grouting with inorganic components, e.g. cement
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
- E21D21/0026—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection characterised by constructional features of the bolts
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Abstract
The invention provides a construction method of a shallow-buried large-span tunnel supporting structure, which comprises the following steps: acquiring surveying information at the position of a tunnel to be excavated; respectively digging advanced pilot tunnels with preset lengths along the extending direction of the tunnel at two sides of the top of the tunnel to be dug; arranging a pipe shed above the tunnel to be excavated and in the soil body between the two advanced pilot tunnels along the extending direction of the tunnel; constructing a plurality of opposite pulling devices above the pipe shed, wherein two ends of each opposite pulling device are respectively fixed on the inner side walls of the two advanced guide holes, and the opposite pulling devices are uniformly arranged along the extending direction of the tunnel to be excavated; a predetermined prestress is applied to each counter-pulling device. The invention can increase the self bearing capacity of the soil body above the large-span tunnel, greatly reduce the thickness of the tunnel supporting structure and reduce the engineering investment.
Description
Technical Field
The application relates to the technical field of tunnel engineering, in particular to a construction method and a supporting structure of a shallow-buried large-span tunnel supporting structure.
Background
At present, a design method and a construction method for a supporting structure of a shallow-buried large-span tunnel at home and abroad are mainly based on the principle of the Xinao method, and secondary expansion is carried out according to the general engineering of each tunnel. The design theory and method of the supporting structure of the shallow-buried large-span tunnel are still in an exploration stage, and most of the structural design is an engineering analogy method based on engineering experience.
In the prior art, the supporting structure of the shallow-buried large-span tunnel is mainly designed by calculating and designing all the overlying soil layers of the tunnel structure as the load of the tunnel structure, and the stability and the supporting function of the overlying soil layers are not considered, so that the using amount of concrete and steel bars is huge, and the tunnel supporting structure is very heavy.
In summary, because the design method of the supporting structure of the shallow-buried large-span tunnel in the prior art has the disadvantages as described above, how to provide a better construction method of the supporting structure of the shallow-buried large-span tunnel and the supporting structure, thereby increasing the bearing capacity of the large-span tunnel covering layer, greatly reducing the thickness of the tunnel supporting structure, and reducing the engineering investment is an urgent problem to be solved in the art.
Disclosure of Invention
In view of the above, the invention provides a construction method of a shallow-buried large-span tunnel supporting structure and the supporting structure, so that the self bearing capacity of a soil body above a large-span tunnel can be increased, the thickness of the tunnel supporting structure is greatly reduced, and the engineering investment is reduced.
The technical scheme of the invention is realized as follows:
a construction method of a shallow-buried large-span tunnel supporting structure comprises the following steps:
step A, acquiring survey information at the position of a tunnel to be excavated;
b, respectively digging advanced pilot tunnels with preset lengths on two sides of the top of the tunnel to be dug along the extending direction of the tunnel;
step C, arranging a pipe shed above the tunnel to be excavated and in the soil body between the two advanced pilot tunnels along the extending direction of the tunnel;
d, constructing a plurality of opposite pulling devices above the pipe shed, wherein two ends of each opposite pulling device are respectively fixed on the inner side walls of the two advanced pilot holes, and the opposite pulling devices are uniformly arranged along the extending direction of the tunnel to be excavated;
and E, applying a preset prestress on each counter-pulling device.
Preferably, the step C includes the steps of:
step C1, arranging a supporting structure on the outer side of the entrance of the tunnel to be excavated;
step C2, uniformly arranging a plurality of drill holes in the soil body along the extending direction of the tunnel at the top of the supporting structure;
step C3, respectively arranging a steel pipe in each drilling hole to form a pipe shed;
and C4, grouting into the soil around the pipe shed through the steel pipe.
Preferably, the step D includes the following steps:
step D1, drilling a plurality of anchor cable through holes in a soil body above the pipe shed, wherein each anchor cable through hole penetrates through the soil body above the pipe shed and the inner side walls of the two advanced pilot holes, and the anchor cable through holes are uniformly arranged along the extending direction of the advanced pilot holes;
d2, arranging a plurality of anchor cables in each anchor cable through hole, wherein two ends of each anchor cable extend into the two advanced pilot holes from two ends of each anchor cable through hole respectively and are fixed on the inner side walls of the two advanced pilot holes through steel anchor heads respectively;
and D3, grouting into the anchor cable through hole to form the counter-pulling device.
Preferably, before the anchor cable through holes are drilled, concrete is coated on the inner side walls of the two leading holes at the positions where the anchor cable through holes need to be drilled.
Preferably, after the step E, the method further comprises the following steps:
and F, excavating the tunnel, and constructing a primary tunnel supporting structure and a secondary lining structure.
A supporting structure comprising: the device comprises two advanced guide holes, a pipe shed and a plurality of opposite pulling devices;
the two leading holes are respectively arranged on two sides of the top of the tunnel to be excavated, and the extending directions of the two leading holes are parallel to the extending direction of the tunnel;
the pipe shed is arranged above the tunnel to be excavated and in a rock mass between the two leading pilot tunnels, and the extending direction of the pipe shed is the same as that of the tunnel to be excavated;
the plurality of opposite-pulling devices are arranged in a soil body above the pipe shed, two ends of each opposite-pulling device are respectively fixed on the inner side walls of the two advanced guide holes, and the plurality of opposite-pulling devices are uniformly arranged along the extending direction of the tunnel to be excavated.
Preferably, the pipe shed comprises: a support structure, a plurality of boreholes, and a plurality of steel pipes;
the supporting structure is arranged on the outer side of the tunnel entrance, and the top of the supporting structure is positioned above the tunnel to be excavated;
the plurality of drill holes are uniformly distributed at the top of the supporting structure and are arranged in the soil body above the tunnel to be excavated in a manner of being parallel to the extending direction of the tunnel;
and each drill hole is internally provided with one steel pipe.
Preferably, the counter-pulling device comprises: the anchor cable comprises a plurality of anchor cable through holes, a plurality of anchor cables, at least two steel anchor heads and a filler;
the anchor cable through holes are arranged in the soil body above the pipe shed, each anchor cable through hole penetrates through the soil body above the pipe shed and the inner side walls of the two advanced guide holes, and the anchor cable through holes are uniformly arranged along the extending direction of the advanced guide holes;
a plurality of anchor cables are arranged in each anchor cable through hole, and two ends of each anchor cable extend into the two advanced pilot holes from two ends of each anchor cable through hole respectively and are fixed on the inner side walls of the two advanced pilot holes respectively through steel anchor heads;
the filling body is filled in gaps among the anchor cables and the anchor cable through holes.
Preferably, the pipe shed further comprises slurry filled in the steel pipe and soil around the pipe shed.
Preferably, one end of the steel pipe is a tapered end, the side wall of the steel pipe is provided with a plurality of through holes, the tapered end of the steel pipe is arranged at the inner end of the drilled hole, and the other end of the steel pipe is arranged at the outer end of the drilled hole.
As can be seen from the above, in the construction method of the shallow-buried large-span tunnel supporting structure and the supporting structure of the present invention, by reasonably arranging the counter-pulling devices, the self-bearing capacity of the soil body above the large-span tunnel can be increased, the load of the tunnel supporting structure can be reduced, the thickness of the tunnel supporting structure can be greatly reduced, and the engineering investment can be reduced.
Drawings
Fig. 1 is a flowchart of a construction method of a shallow-buried large-span tunnel supporting structure in an embodiment of the present invention.
FIG. 2 is a flowchart of step 103 in an embodiment of the present invention.
FIG. 3 is a flowchart of step 104 in an embodiment of the present invention.
Figure 4 is a cross-sectional schematic view of a supporting structure in an embodiment of the invention.
Fig. 5 is a schematic longitudinal sectional view of a supporting structure in an embodiment of the present invention.
FIG. 6 is a schematic structural view of a steel pipe in an embodiment of the present invention.
Fig. 7 is a schematic structural diagram of a counter-pulling device in an embodiment of the present invention.
Detailed Description
In order to make the technical scheme and advantages of the invention more apparent, the invention is further described in detail with reference to the accompanying drawings and specific embodiments.
Fig. 1 is a flowchart of a construction method of a shallow-buried large-span tunnel supporting structure in an embodiment of the present invention.
As shown in fig. 1, the construction method of the shallow-buried large-span tunnel supporting structure in the embodiment of the present invention includes the following steps:
Before tunnel construction, a cross-section contour line of a tunnel to be excavated is marked on a soil body of a tunnel opening of the tunnel to be excavated according to design parameters of the tunnel, so that the shape and the size of the cross-section of the tunnel are determined. When the tunnel is excavated, the soil body inside the section contour line of the tunnel is continuously excavated along the direction perpendicular to the plane where the section contour line is located towards the inside of the soil body until the whole tunnel is excavated. Before the tunnel is excavated, the general engineering needs to be known, and the supporting structure needs to be constructed and other preparation works, so that geological exploration and measurement can be performed on the position of the tunnel to be excavated, or the geological exploration and measurement can be directly acquired from the existing design parameters, so that the exploration information on the position of the tunnel to be excavated can be obtained.
Additionally, by way of example, in one particular embodiment of the invention, the survey information may include: and surveying data such as tunnel vault soil covering thickness, ground load, vault soil covering volume weight, internal friction angle, soil body cohesive force and the like. The survey information may be used or viewed when constructing a supporting structure (e.g., calculating the prestress of a tension device, etc.).
And 102, respectively digging advanced pilot tunnels 1 with preset lengths on two sides of the top of the tunnel to be dug along the extending direction of the tunnel.
Referring to fig. 4 and 5, leading holes may be dug at both ends of the top of the tunnel to be dug along the extending direction of the tunnel according to the cross-sectional contour line of the tunnel to be dug, so that the initial stress of the rock part may be released through the two leading holes, the deformation of the supporting structure caused by the formal excavation of the tunnel may be reduced, the pressure acting on the supporting structure may also be reduced, and further, the occurrence of safety accidents may be avoided; in addition, two leading tunnels also can be convenient for the construction of later stage split device.
In addition, in the actual construction process, the whole tunnel is generally excavated in multiple sections. During specific construction, the whole tunnel can be divided into a plurality of sections, the first section of tunnel is excavated firstly, and then the excavation work of the first section of tunnel is circulated for a plurality of times until the whole tunnel is opened; moreover, each time a section of tunnel is excavated, construction of a supporting structure is performed. Therefore, the length of the leading tunnel 1 dug each time can be respectively predetermined according to the length of each tunnel section in the actual application scene.
And 103, arranging a pipe shed 14 above the tunnel to be excavated and in the soil body between the two leading tunnels along the extending direction of the tunnel.
In order to avoid collapse of soil above the tunnel after tunnel excavation, a pipe shed along the extending direction of the tunnel can be arranged at the top of the tunnel to be excavated before tunnel excavation, so that the soil above the tunnel can be supported to a certain extent through the pipe shed to prevent collapse when the tunnel is excavated.
In addition, in the technical scheme of this application, can set up above-mentioned pipe canopy through multiple concrete implementation. The following will describe the technical solution of the present application in detail by taking one of the specific modes as an example.
For example, in one embodiment of the present invention, as shown in fig. 2, the step 103 may include the following steps:
referring to fig. 4 and 5, in order to provide the pipe shed at the top of the tunnel to be excavated, a supporting structure may be first provided at the outer side of the entrance of the tunnel to be excavated according to the cross-sectional contour line of the tunnel, and the top of the supporting structure is located above the tunnel to be excavated, so that the pipe shed may be conveniently positioned and constructed above the tunnel to be excavated, and may also have a certain supporting effect on the pipe shed.
step 33, respectively arranging a steel pipe 42 in each drilling hole to form a pipe shed 14;
preferably, as an example, one end of the steel tube 42 may be a tapered end, and the side wall may have a plurality of through holes, the tapered end of the steel tube is disposed at the inner end of the drilled hole, and the other end of the steel tube is disposed at the outer end of the drilled hole.
Since the top of the support structure 104 is located above the tunnel to be excavated, the shed formed by the plurality of steel pipes 42 disposed at the top of the support structure is also located above the tunnel to be excavated. The steel pipe is driven into the soil body from the drill hole at the top of the supporting structure, and one end of the steel pipe is a conical end, so that the steel pipe can enter the drill hole more conveniently and can penetrate into the soil body above the tunnel to be excavated. When the tunnel is excavated, along with the movement of the excavation working face, the soil body which is not excavated in the tunnel plays a supporting role for the conical end of the steel pipe because the conical end of the steel pipe is above the soil body which is not excavated in the tunnel; the other end of the steel pipe is arranged in a drill hole of the supporting structure, and the supporting structure plays a supporting role for the end of the steel pipe, so that the pipe shed forms a stable simple supporting beam structure, the effect of bearing the loosening pressure of the upper soil body or transmitting the upper load can be played, and the soil body above the supporting structure is prevented from falling and collapsing when the tunnel is excavated.
And step 34, grouting the soil around the pipe shed through the steel pipe 41.
Because the side wall of each steel pipe 42 is provided with a plurality of through holes, when grouting is carried out in the steel pipe, slurry can flow out of the through holes in the side wall of the steel pipe and further flow into soil gaps around each steel pipe, so that loose soil around the pipe shed is cemented and consolidated, the physical and mechanical properties of weak (broken) surrounding rocks are improved, the self-bearing capacity of the surrounding rocks is enhanced, and the purpose of reinforcing the surrounding rocks around the pipe shed is achieved. In addition, a certain water stopping effect can be further achieved, and the pipe shed can become a protective shed for subsequent tunnel excavation.
And 104, constructing a plurality of opposite-pulling devices 10 above the pipe shed, wherein two ends of each opposite-pulling device are respectively fixed on the inner side walls of the two advanced guide holes, and the opposite-pulling devices are uniformly arranged along the extending direction of the tunnel to be excavated.
In order to improve the vertical bearing capacity of the soil body above the pipe shed, a counter-pulling device which transversely (transversely refers to the direction perpendicular to the extending direction of the advanced pilot tunnel) penetrates through the soil body above the pipe shed is arranged in the two advanced pilot tunnels along the extending direction of the advanced pilot tunnels above the pipe shed, and the counter-pulling device exerts transverse extrusion force on the soil body above the pipe shed between the two advanced pilot tunnels and compresses the partial soil body, so that the vertical bearing capacity of the partial soil body can be improved, and the soil body above the tunnel can be further prevented from collapsing in the excavation process of the tunnel. In addition, because the pipe shed and the opposite-pulling device are arranged above the tunnel to be excavated, the upper soil body can be supported, and therefore the thickness of a primary supporting structure and the thickness of a secondary lining in the later-stage tunnel can be reduced.
In the technical solution of the present invention, the step 104 can be implemented by using various implementation methods. The technical solution of the present invention will be described in detail below by taking one implementation manner as an example.
For example, in a preferred embodiment of the present invention, as shown in fig. 3, the step 104 may include the following steps:
and 43, grouting the anchor cable through hole 16 to form the counter-pulling device 10.
A plurality of anchor cable through holes which are distributed along the extending direction of the advanced pilot tunnel and run through the two advanced pilot tunnels are arranged on the inner side walls of the two advanced pilot tunnels above the pipe shed, and a plurality of anchor cables are arranged in the anchor cable through holes through steel anchor heads, so that the vertical bearing capacity of the partial soil body can be improved. Through the slip casting in to the anchor rope through-hole to can make the thick liquid be full of the anchor rope through-hole, when realizing anchor rope through-hole full length anchor, the thick liquid spreads in to the soil body gap around the anchor rope through-hole, plays the solidification of bonding to the soil body around the anchor rope through-hole, further improves the wholeness and the vertical bearing capacity of the soil body.
In addition, in the embodiment of the present invention, before drilling the anchor cable through hole, concrete 13 may be coated on the inner sidewalls of the two leading tunnels at the position where the anchor cable through hole needs to be drilled, so as to solidify the soil body and prevent the soil body from scattering or breaking during drilling.
Preferably, as an example, a preset prestress can be applied to each anchor cable in the opposite pulling device, and each anchor cable is locked and fixed through a steel anchor head arranged on the inner side walls of the two pilot holes.
The prestress is applied to each anchor cable in each opposite pulling device, so that the reliability of the structure of the opposite pulling device can be improved, and the opposite pulling device is prevented from being damaged under the action of a soil body after a tunnel is excavated.
Further, as an example, in the embodiment of the present invention, the prestress force F of the counter pulling device may be calculated by the following formula p ：
In the formula, h is the thickness of the tunnel vault soil covering; p is the ground load; gamma is the volume weight of vault soil covering; phi is an internal friction angle; c is the cohesive force of the soil body; and s is the horizontal distance of the anchor cables.
In addition, in the technical scheme of the application, the specific value of the anchor cable horizontal spacing s can be preset according to actual specific conditions such as site conditions, construction convenience, engineering experience, engineering investment ratio selection and the like. For example, in an embodiment of the present invention, the horizontal distance s between the anchor cables may generally be 3 to 6 meters (m).
Through the arrangement of the counter-pulling device, the vertical bearing capacity of the soil body can be improved by increasing the transverse extrusion force, and the vertical bearing capacity sigma of the overlying soil body L Can be calculated as follows:
σ L ＝σ n ·tanφ+C (2)
in the formula, σ n The transverse extrusion force of the soil body is shown, phi is the internal friction angle of the soil body, and C is the cohesive force of the soil body.
Therefore, according to the above formula, it is possible to increase the lateral pressing force σ n Thereby improving the vertical bearing capacity sigma of the overlying soil body L Therefore, the opposite pulling device is arranged in the soil body above the pipe shed, and the prestress of the opposite pulling device is applied to improve the compressive stress at two sides of the arch crown covering soil, so that the vertical bearing capacity of the arch crown covering soil is improved; further, vault tensile stress areas caused by tunnel excavation can be eliminated.
In addition, as an example, in a preferred embodiment of the present invention, after the step 105, the following steps may be further included:
and 106, excavating the tunnel, and constructing the primary tunnel supporting structure 100 and the secondary lining structure 200.
In a preferred embodiment of the present invention, the step 105 may further include the steps of:
step 61, excavating a left soil body 3 and a right soil body 4 on the upper part of the tunnel, and constructing a tunnel vault primary support structure;
step 62, excavating a left soil body 5 and a right soil body 6 in the middle of the tunnel, and constructing a primary tunnel side wall supporting structure;
step 63, excavating a tunnel middle soil body 7;
step 64, excavating a left soil body 8 and a right soil body 9 at the lower part of the tunnel, and constructing an inverted arch of the tunnel to form a primary tunnel supporting structure 100, wherein the primary tunnel supporting structure comprises a primary tunnel arch crown supporting structure, a primary tunnel side wall supporting structure and an inverted arch of the tunnel;
and 65, constructing a secondary tunnel lining structure 200 on the inner side of the primary tunnel supporting structure.
The tunnel section is divided into a plurality of excavation areas, excavation is carried out according to a reasonable excavation sequence, and therefore construction safety and stability of surrounding rocks can be guaranteed. In addition, in the process of excavating the tunnel, the excavation work and the construction of the primary tunnel supporting structure are synchronously carried out, and the whole tunnel is excavated in a subsection mode, so that after one section of tunnel is excavated, the primary tunnel supporting structure and the secondary lining are arranged, the stability of the section of tunnel which is treaded empty can be ensured, the construction of the next section of tunnel can be carried out, and the operation is circulated for many times until the whole section of tunnel is excavated, and the construction of the tunnel is completed.
According to the construction method of the shallow-buried large-span tunnel supporting structure, advanced pilot tunnels are constructed on two sides of the top of a tunnel to be excavated, so that initial stress of a rock part can be released, and a construction space is provided for a counter-pulling device; through treating to dig tunnel top and set up the pipe shed and to drawing the device to can improve the cohesion and the internal friction angle of the tunnel top soil body, improve the vertical bearing capacity of vault earthing, reduce the load of preliminary bracing structure and secondary lining in the tunnel of later stage, and then can reduce preliminary bracing structure and secondary lining's in the tunnel thickness by a wide margin, reduce the engineering investment.
In addition, according to the method provided by the invention, the invention also provides a corresponding supporting structure, and particularly refers to fig. 4 to 7.
As shown in fig. 4 and 5, the supporting structure includes: two leading holes 1, a pipe shed 14 and a plurality of opposite pulling devices 10;
the two leading holes 1 are respectively arranged at two sides of the top of the tunnel to be excavated, and the extending directions of the two leading holes are parallel to the extending direction of the tunnel;
the pipe shed 14 is arranged in a rock mass which is positioned above the tunnel to be excavated and between the two leading pilot tunnels, and the extension direction of the pipe shed 14 is the same as that of the tunnel to be excavated;
the plurality of counter-pulling devices 10 are arranged in a soil body above the pipe shed 14, two ends of each counter-pulling device are respectively fixed on the inner side walls of the two advanced guide holes, and the plurality of counter-pulling devices are uniformly arranged along the extending direction of the tunnel to be excavated.
The pipe shed is arranged above the tunnel, so that the soil body above the pipe shed can be supported, and the opposite pulling device is arranged in the soil body above the pipe shed, so that the vertical bearing capacity of the soil body above the large-span tunnel can be increased, the load of a tunnel supporting structure is reduced, the thickness of the tunnel supporting structure is greatly reduced, and the engineering investment is reduced.
In the technical solution of the present invention, the above-mentioned supporting structure can be realized by using various implementation methods. The technical solution of the present invention will be described in detail below by taking one implementation manner as an example.
For example, preferably, in one embodiment of the present invention, as shown in fig. 4-6, the pipe shed 14 may include a support structure 104, a plurality of bores 41, and a plurality of steel pipes 42;
the support structure 104 is arranged outside the tunnel entrance, and the top of the support structure is positioned above the tunnel to be excavated;
the plurality of drill holes 41 are uniformly distributed at the top of the supporting structure 104 and are arranged in the soil body above the tunnel to be excavated in parallel to the extending direction of the tunnel;
one steel pipe 42 is arranged in each bore 41.
Preferably, the pipe shed 14 may further comprise a slurry filled in the steel pipe 42 and the soil surrounding the pipe shed.
Preferably, as an example, one end of the steel tube 42 may be a tapered end, and the side wall may have a plurality of through holes, the tapered end of the steel tube is disposed at the inner end of the drilled hole, and the other end of the steel tube is disposed at the outer end of the drilled hole.
A plurality of drill holes are formed in the top of the supporting structure, and a plurality of steel pipes are arranged in the drill holes, so that a pipe shed with a supporting function can be formed above the tunnel to be excavated. One end of the steel pipe is provided with a conical end, so that the steel pipe is conveniently placed in the drilled hole during construction of the pipe shed. The side wall of steel pipe sets up a plurality of through-holes, through to the intraductal slip casting, the thick liquid can flow into the soil body around the piping erection from the through-hole on the steel pipe side wall, plays the solidification effect to soil body around to can prevent to take place to collapse when excavating the tunnel.
For another example, preferably, in an embodiment of the present invention, as shown in fig. 7, the counter-pulling device 10 may include: a plurality of anchor cable through holes 16, a plurality of anchor cables 15, at least two steel anchor heads 11 and a filler 17;
the anchor cable through holes 16 are formed in the soil body above the pipe shed, each anchor cable through hole penetrates through the soil body above the pipe shed and the inner side walls of the two advanced pilot tunnels, and the anchor cable through holes are uniformly arranged along the extending direction of the advanced pilot tunnels;
a plurality of anchor cables 15 are arranged in each anchor cable through hole 16, and two ends of each anchor cable extend into the two advanced pilot holes from two ends of each anchor cable through hole respectively and are fixed on the inner side walls of the two advanced pilot holes respectively through steel anchor heads 11;
the filler body 17 is filled in the gaps between the plurality of anchor cables 15 and the anchor cable through-holes 16.
Preferably, the filler may be a slurry.
Through set up many anchor ropes in every anchor rope through-hole, can improve the horizontal extrusion force of anchor rope to the canopy top soil body to slip casting in the anchor rope through-hole, thereby can make the thick liquid be full of the anchor rope through-hole, when realizing anchor rope through-hole full length anchor, the thick liquid spreads in to the soil body gap around the anchor rope through-hole, plays the solidification of bonding to the soil body around the anchor rope through-hole, further improves the wholeness and the vertical bearing capacity of the soil body.
Preferably, as shown in fig. 4, concrete 13 may be coated on the inner sidewalls of the two leading holes at the positions where the anchor cable through holes need to be drilled, so as to consolidate the soil and prevent the soil from scattering or breaking during drilling.
In addition, as an example, in a preferred embodiment of the present invention, as shown in fig. 5, the supporting structure may further include a tunnel preliminary supporting structure 100 and a secondary lining structure 200; the tunnel primary supporting structure 100 is arranged on the inner wall of the tunnel; the two lining structures are arranged on the inner wall of the primary tunnel supporting structure.
Preferably, the tunnel preliminary bracing structure 100 may include a tunnel vault preliminary bracing structure, a tunnel side wall preliminary bracing structure, and a tunnel invert.
Because the pipe shed and the opposite-pulling device are arranged above the tunnel before the tunnel is excavated, the vertical bearing capacity of a soil body above the tunnel can be effectively increased, and the load of a tunnel supporting structure is reduced, so that the thicknesses of a tunnel primary supporting structure, a secondary lining structure and the like arranged after the tunnel is excavated can be reduced, and the engineering investment is reduced.
In summary, by arranging the leading tunnels on the two sides of the tunnel, the counter-pulling device can be constructed in the leading tunnel. By arranging the counter-pulling device, soil bodies above the large-span tunnel are compacted, the bearing capacity of the soil bodies coated on the tunnel is greatly increased, the load of the tunnel structure is reduced, the stability of soil layers and the structure is improved, the tunnel construction safety is improved, the construction risk is reduced, the thickness of the tunnel supporting structure can be greatly reduced, and the engineering investment is reduced; furthermore, temporary cross braces and vertical braces of the oversized cross-tunnel can be reduced, the influence of temporary support measures on a working face is reduced, and the construction efficiency is improved.
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 made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A construction method of a shallow-buried large-span tunnel supporting structure is characterized by comprising the following steps:
step A, acquiring survey information at the position of a tunnel to be excavated;
b, respectively digging advanced pilot tunnels with preset lengths on two sides of the top of the tunnel to be dug along the extending direction of the tunnel;
step C, arranging a pipe shed above the tunnel to be excavated and in the soil body between the two advanced pilot tunnels along the extending direction of the tunnel;
d, constructing a plurality of opposite pulling devices above the pipe shed, wherein two ends of each opposite pulling device are respectively fixed on the inner side walls of the two advanced pilot holes, and the opposite pulling devices are uniformly arranged along the extending direction of the tunnel to be excavated;
and E, applying preset prestress on each counter-pulling device.
2. The method of claim 1, wherein step C comprises the steps of:
step C1, arranging a supporting structure on the outer side of the entrance of the tunnel to be excavated;
step C2, uniformly arranging a plurality of drill holes in the soil body along the extending direction of the tunnel at the top of the supporting structure;
step C3, respectively arranging a steel pipe in each drilling hole to form a pipe shed;
and C4, grouting into the soil around the pipe shed through the steel pipe.
3. The method of claim 1, wherein said step D comprises the steps of:
step D1, drilling a plurality of anchor cable through holes in a soil body above the pipe shed, wherein each anchor cable through hole penetrates through the soil body above the pipe shed and the inner side walls of the two advanced pilot holes, and the anchor cable through holes are uniformly arranged along the extending direction of the advanced pilot holes;
d2, arranging a plurality of anchor cables in each anchor cable through hole, wherein two ends of each anchor cable extend into the two advanced pilot holes from two ends of each anchor cable through hole respectively and are fixed on the inner side walls of the two advanced pilot holes through steel anchor heads respectively;
and D3, grouting into the anchor cable through hole to form the counter-pulling device.
4. The method as claimed in claim 3, wherein before the anchor cable through holes are drilled, concrete is coated on the inner side walls of the two leading tunnels at positions where the anchor cable through holes are to be drilled.
5. The method according to claim 1, wherein after the step E, further comprising the steps of:
and F, excavating the tunnel, and constructing a primary tunnel supporting structure and a secondary lining structure.
6. A supporting structure, comprising: the device comprises two advanced guide holes, a pipe shed and a plurality of opposite pulling devices;
the two pilot tunnels are respectively arranged on two sides of the top of the tunnel to be excavated, and the extending directions of the two pilot tunnels are parallel to the extending direction of the tunnel;
the pipe shed is arranged in a rock mass which is positioned above the tunnel to be excavated and between the two leading pilot tunnels, and the extension direction of the pipe shed is the same as that of the tunnel to be excavated;
the plurality of opposite-pulling devices are arranged in a soil body above the pipe shed, two ends of each opposite-pulling device are respectively fixed on the inner side walls of the two advanced pilot tunnels, and the plurality of opposite-pulling devices are uniformly arranged along the extending direction of the tunnel to be excavated.
7. The support structure of claim 6, wherein the pipe shed comprises: a support structure, a plurality of boreholes, and a plurality of steel pipes;
the supporting structure is arranged on the outer side of the tunnel entrance, and the top of the supporting structure is positioned above the tunnel to be excavated;
the plurality of drill holes are uniformly distributed at the top of the supporting structure and are arranged in the soil body above the tunnel to be excavated in a manner of being parallel to the extending direction of the tunnel;
and each drill hole is internally provided with one steel pipe.
8. The supporting structure of claim 6, wherein the counter-pulling device comprises: the anchor cable comprises a plurality of anchor cable through holes, a plurality of anchor cables, at least two steel anchor heads and a filler;
the anchor cable through holes are arranged in the soil body above the pipe shed, each anchor cable through hole penetrates through the soil body above the pipe shed and the inner side walls of the two advanced guide holes, and the anchor cable through holes are uniformly arranged along the extending direction of the advanced guide holes;
a plurality of anchor cables are arranged in each anchor cable through hole, and two ends of each anchor cable extend into the two advanced pilot holes from two ends of each anchor cable through hole respectively and are fixed on the inner side walls of the two advanced pilot holes respectively through steel anchor heads;
the filling body is filled in gaps among the anchor cables and the anchor cable through holes.
9. The supporting structure of claim 7, wherein the pipe shed further comprises a slurry filled in the steel pipe and the soil surrounding the pipe shed.
10. The support structure of claim 7, wherein one end of the steel pipe is a tapered end, and the side wall has a plurality of through holes, the tapered end of the steel pipe being disposed at an inner end of the bore hole, and the other end of the steel pipe being disposed at an outer end of the bore hole.
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| CN108457658A (en) * | 2018-03-14 | 2018-08-28 | 济南城建集团有限公司 | A kind of texture stratum tunnel list hole bidirectional construction crosses section constructing method |
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