CN114673528B - Tunnel top cavity supporting method - Google Patents
Tunnel top cavity supporting method Download PDFInfo
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- CN114673528B CN114673528B CN202210313949.1A CN202210313949A CN114673528B CN 114673528 B CN114673528 B CN 114673528B CN 202210313949 A CN202210313949 A CN 202210313949A CN 114673528 B CN114673528 B CN 114673528B
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- 238000000034 method Methods 0.000 title claims abstract description 31
- 230000008093 supporting effect Effects 0.000 title claims abstract description 21
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 143
- 239000010959 steel Substances 0.000 claims abstract description 143
- 239000002893 slag Substances 0.000 claims abstract description 18
- 238000009412 basement excavation Methods 0.000 claims abstract description 17
- 239000011435 rock Substances 0.000 claims abstract description 16
- 239000004567 concrete Substances 0.000 claims abstract description 14
- 238000009434 installation Methods 0.000 claims abstract description 11
- 238000005507 spraying Methods 0.000 claims abstract description 9
- 238000005422 blasting Methods 0.000 claims abstract description 5
- 230000003014 reinforcing effect Effects 0.000 claims description 21
- 238000007599 discharging Methods 0.000 claims description 7
- 238000003466 welding Methods 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 239000004576 sand Substances 0.000 claims description 3
- 239000011378 shotcrete Substances 0.000 claims description 3
- 238000010276 construction Methods 0.000 description 13
- 239000002689 soil Substances 0.000 description 9
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 4
- 238000007596 consolidation process Methods 0.000 description 4
- 230000002411 adverse Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000002002 slurry Substances 0.000 description 2
- 239000000956 alloy Substances 0.000 description 1
- 238000010009 beating Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000005536 corrosion prevention Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000013049 sediment Substances 0.000 description 1
- 239000010454 slate Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/14—Lining predominantly with metal
- E21D11/18—Arch members ; Network made of arch members ; Ring elements; Polygon elements; Polygon elements inside arches
- E21D11/183—Supporting means for arch members, not provided for in E21D11/22
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
- E21D11/105—Transport or application of concrete specially adapted for the lining of tunnels or galleries ; Backfilling the space between main building element and the surrounding rock, e.g. with concrete
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- 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
- E21D11/107—Reinforcing elements therefor; Holders for the reinforcing elements
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/14—Lining predominantly with metal
- E21D11/28—Longitudinal struts, i.e. longitudinal connections between adjoining arches
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/20—Hydro energy
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- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Structural Engineering (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Lining And Supports For Tunnels (AREA)
Abstract
The invention discloses a method and a structure for supporting a cavity at the top of a tunnel, which relate to the field of geotechnical engineering and aim to support an unstable cavity at the top of the tunnel after the tunnel is broken, so that the unstable cavity can safely and quickly pass through a weak broken surrounding rock section. The technical scheme adopted by the invention is as follows: during blasting excavation of weak broken surrounding rock tunnel sections, an unstable cavity appears at the position close to the top of the tunnel face, and a steel arch sheet, an arch sheet support, arch feet and arch foot fixing pieces are manufactured for standby; then removing footing scum of the tunnel, respectively erecting arch feet on two side walls of the tunnel, respectively and fixedly mounting arch sheet supports on the arch feet, and mounting steel arch sheets; slag is discharged again, and the installation operation of the steel arch sheets of the remaining hole sections is carried out until the tunnel face; then hanging steel bars on the inner side of the arch springing and spraying concrete to form a structural layer; and finally backfilling the unstable cavity through the backfilling hole. The method is used for treating unstable cavities at the top of the tunnel of the weak broken surrounding rock tunnel section, which is close to the tunnel face.
Description
Technical Field
The invention relates to the field of geotechnical engineering, in particular to a method and a structure for supporting a top cavity in a tunnel excavation process.
Background
In the tunnel excavation process, under the geological conditions of weak broken surrounding rock tunnel sections, particularly carbonaceous slates developed by groundwater, the risk of collapse is relatively high, the situation that loose rock and soil with relatively high water content at the top of the tunnel after blasting is prone to falling down sometimes occurs, and if the loose rock and soil is not treated in time, larger loss can be caused.
At present, the treatment measures for the working condition comprise the following methods: firstly, after loose rock mass at the top of a tunnel is basically stable and larger rock-soil blocks are not fallen, slag discharging construction is carried out, and then the hollow cavity part is supported, backfilled and grouted. Secondly, if loose rock soil at the top of the tunnel cannot be stabilized in a short time, a phenomenon that larger rock soil blocks fall off occurs, and two treatment schemes are generally provided according to the actual situation on site, wherein the scheme (1): the phenomenon of block falling is serious, the cavity at the top is large, after the loose rock soil body to be dropped fully covers the face, grouting consolidation is carried out on the loose slag body, backfilling treatment is carried out on the cavity, and after the consolidation strength is designed, hole excavation and slag removal are carried out by adopting an excavation mode of reserved core soil; scheme (2): if the hole slag and the falling blocks are insufficient to completely cover the tunnel face, covering the tunnel face by adopting a slag backfilling mode, and grouting and solidifying the loose slag body, wherein the subsequent treatment mode is the same as that of the scheme (1).
The first treatment method has the defects that: first, it may take a long time to wait, and untimely support may exacerbate collapse risk; secondly, under the condition that no protective measures are taken, a large safety risk still exists in supporting the cavity at the top of the tunnel; thirdly, the cavity is refilled and grouting is carried out, the working procedure is complex, the process requirement is strict, and the slurry consolidation requires a certain time, so that the construction progress is adversely affected. The second treatment method has the following disadvantages: on one hand, covering the face by backfilling slag requires a certain time, and slag is carried out to the slag body in the follow-up process, so that the construction progress is greatly influenced; on the other hand, the adverse effect of backfill grouting on cavities is not as good as the third point of the first treatment method.
Disclosure of Invention
The invention firstly provides a method for supporting a cavity at the top of a tunnel, which aims to support an unstable cavity at the top of the tunnel after the tunnel is blasted, and safely and rapidly passes through a weak broken surrounding rock section.
The technical scheme adopted by the invention is as follows: the tunnel top cavity supporting method is characterized in that an unstable cavity appears at the top of a tunnel close to a tunnel face during blasting excavation of a weak broken surrounding rock tunnel section, and the supporting treatment method comprises the following steps:
s1, manufacturing a steel arch sheet, an arch sheet support, arch feet and arch foot fixing pieces for standby, wherein the steel arch sheet is a strip-shaped steel plate bent into an arch shape, and one side of the arch sheet support is provided with a continuous arch sheet clamping groove.
The arch sheet bracket is a U-shaped channel steel with a U-shaped section, the front end of the channel steel is sharp, one side of the channel steel forms a U-shaped arch sheet clamping groove, and the width of the arch sheet clamping groove is larger than the thickness of the steel arch sheet; the arch foot is shaped steel, and the arch foot fixing piece is a locking foot anchor rod. For example, the steel arch sheet has a thickness of 1-2 cm and a width of 20-50 cm; the width of the arch sheet clamping groove of the arch sheet bracket is 1.5-2.0 times of the thickness of the steel arch sheet, and the depth of the arch sheet clamping groove is 3-5 cm; the arch foot is I16I-steel.
S2, removing footing scum of the tunnel, respectively erecting arch feet on two side walls of the tunnel, and fixing the arch feet on the side walls through arch foot fixing pieces. For example, the arch springing is shaped steel, and every shaped steel interval arrangement is fixed in the lateral wall of tunnel through two piece at least lock foot stock, and every shaped steel's verticality deviation is less than 2.
In order to improve the stability between the arch springings, at least one transverse reinforcing rib is fixedly arranged between the arch springings of any side wall of the tunnel. The transverse reinforcing rib is preferably parallel to the axis of the tunnel, the transverse reinforcing rib is preferably welded with the arch springing, and one end of the transverse reinforcing rib, which is far away from the tunnel face, is preferably fixedly connected with the arch springing part of the existing steel support.
S3, arch sheet supports are fixedly installed on arch feet of two side walls of the tunnel respectively, arch sheet clamping grooves of the arch sheet supports face upwards, the two arch sheet supports are parallel to the axis of the tunnel, and the front ends of the arch sheet supports are inserted into the tunnel face. For example, the arch sheet support and the arch springing are welded or connected by bolts, and the front end of the arch sheet support is inserted into the face for 1-2 m.
S4, removing slag bodies affecting the installation of the steel arch sheets on the tunnel excavation profile surface from one end far away from the tunnel surface, installing the steel arch sheets one by one to the top of the tunnel, attaching the outer sides of the steel arch sheets to the tunnel excavation profile surface, respectively arranging two ends of the steel arch sheets in arch sheet clamping grooves of the arch sheet support, and leaving no gaps between adjacent steel arch sheets; at least one backfill hole is reserved corresponding to at least one steel arch sheet where an unstable cavity exists at the top of the tunnel.
Further is: at least one transverse connecting rib is fixedly arranged between the steel arch sheets of the same side wall of the tunnel, and the transverse connecting rib is positioned on the inner side of the steel arch sheets. For example, the transverse connecting ribs are welded and fixed on the steel arch sheet, and the length direction of the transverse connecting ribs is parallel to the axis of the tunnel.
S5, slag discharging operation is carried out on tunnel sections in the installation range of the steel arch sheets, and after slag discharging is finished, the steel arch sheet installation operation of the remaining tunnel sections is continued until the tunnel face is reached.
S6, hanging a reinforcing mesh on the inner side of the arch springing and spraying concrete to form a structural layer. If the gaps between the adjacent arch legs are larger, dry masonry is firstly stacked at the gaps between the arch legs for filling, then a reinforcing steel bar net is hung and concrete is sprayed, and the thickness of the sprayed concrete is 8-10 cm.
S7, backfilling the unstable cavity through the backfilling hole. For example, the unstable cavity is backfilled with dry sand, and the backfill thickness is determined by design calculation.
The invention also provides a supporting structure for the cavity at the top of the tunnel, which aims to support an unstable cavity at the top of the tunnel after the tunnel is blasted, so that the surrounding rock tunnel section can be safely and rapidly broken through the weakness. The tunnel top cavity supporting structure comprises arch feet, arch foot fixing pieces, arch sheet supports and steel arch sheets, wherein the arch feet are used for being erected on two side walls of a tunnel, the arch foot fixing pieces are used for fixing the arch feet on the side walls of the tunnel, the arch sheet supports are fixedly installed on the arch feet, the steel arch sheets are erected between the two arch sheet supports and are parallel to the axis of the tunnel, the two arch sheet supports are provided with continuous arch sheet clamping grooves, the opening of each arch sheet clamping groove faces upwards, each steel arch sheet is a strip-shaped steel plate bent into an arch, at least two steel arch sheets are at least provided with at least one backfill hole, two ends of each steel arch sheet are respectively arranged in the arch sheet clamping grooves of the corresponding arch sheet supports, and the steel arch sheets are spliced in a sealing way; the inner side of the arch foot is a structural layer formed by hanging a reinforcing mesh and spraying concrete.
Further is: the arch foot is shaped steel, and the arch foot fixing piece is a foot locking anchor rod; the arch sheet support is a U-shaped channel steel with a U-shaped section, the front end of the channel steel is sharp, one side of the channel steel forms a U-shaped arch sheet clamping groove, and the width of the arch sheet clamping groove is larger than the thickness of the steel arch sheet.
Specific: the thickness of the steel arch sheet is 1-2 cm, and the width is 20-50 cm; the width of the arch sheet clamping groove of the arch sheet bracket is 1.5-2.0 times of the thickness of the steel arch sheet, and the depth of the arch sheet clamping groove is 3-5 cm; the arch foot is I16I-steel.
Specific: each section steel is arranged at intervals and fixed through at least two lock foot anchor rods, and the deviation of the verticality of each section steel is smaller than 2 degrees.
Further is: at least one transverse reinforcing rib is fixedly arranged between arch feet of the same side wall of the tunnel. The transverse reinforcing ribs are preferably parallel to the axis of the tunnel, and the transverse reinforcing ribs are preferably welded with the arch springing.
Further, it is: and the gaps between the arch feet are piled up with dry masonry, and the inner sides of the arch feet and the dry masonry are structural layers formed by hanging reinforcing steel bar meshes and spraying concrete.
Specific: the arch sheet bracket and the arch foot are connected by welding or bolts.
Further is: at least one transverse connecting rib is fixedly arranged between the steel arch sheets, and the transverse connecting rib is positioned at the inner side of the steel arch sheets. In order to facilitate construction, the transverse connecting ribs are welded and fixed on the steel arch sheet, and the length direction of the transverse connecting ribs is parallel to the axis of the tunnel.
The beneficial effects of the invention are as follows: the invention is suitable for weak broken surrounding rock tunnel sections, such as the working condition that an unstable cavity appears at the top after the tunnel is blasted under the geological condition of the carbonaceous slate of groundwater development, and can rapidly carry out construction operation. The steel arch sheet is reserved with a backfill hole, and the unstable cavity is backfilled through the backfill hole on the steel arch sheet, so that the stress structure on the outer side of the steel arch sheet is improved. The dry sand is backfilled into the unstable cavity, so that the construction difficulty is reduced, the operation is simple, the construction is quick, the slurry consolidation time is saved, the treatment effect is improved, the subsequent excavation operation can be quickly carried out after backfilling, and the adverse effect on the construction progress is reduced to the greatest extent.
Drawings
FIG. 1 is a schematic view of a tunnel top cavity after being treated in accordance with the present invention.
Reference numerals: steel arch sheet 1, arch sheet support 2, arch foot 3, backfill hole 4, transverse reinforcing rib 5, steel support 6, transverse connecting rib 7 and dry masonry 8.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
As shown in FIG. 1, the method for supporting the cavity at the top of the tunnel is used for working conditions of unstable cavities at the top of the tunnel close to a face during blasting excavation of weak broken surrounding rock tunnel sections, and comprises the following steps:
s1, manufacturing a steel arch sheet 1, an arch sheet bracket 2, an arch springing 3 and an arch springing fixing piece for standby. The steel arch sheet 1 is a strip steel plate bent into an arch shape, the steel arch sheet 1 can also be made of other metal or alloy materials, and the steel arch sheet 1 is used for being installed on the top of a tunnel and forming a supporting effect on the top of the tunnel, so that the arch shape of the steel arch sheet 1 is preferably consistent with the excavation contour line of the tunnel. For example, the steel arch sheet 1 is made of a common steel plate with a thickness of 1-2 cm, and the width of the steel arch sheet 1 can be 20-50 cm according to practical situations.
The arch sheet support 2 is used for supporting and fixing the steel arch sheet 1, one side of the arch sheet support 2 is provided with a continuous arch sheet clamping groove, and two ends of the steel arch sheet 1 are arranged in the arch sheet clamping groove. The arch sheet clamping groove can be of an open structure in a right angle shape or a U-shaped groove-shaped structure. For example, the arch sheet bracket 2 is a channel steel with a U-shaped section, one side of the channel steel naturally forms an arch sheet clamping groove with a U-shaped section, and the width of the arch sheet clamping groove is larger than the thickness of the steel arch sheet 1, so that one end of the steel arch sheet 1 is inserted into the arch sheet clamping groove, for example, the width of the arch sheet clamping groove is 1.5-2.0 times of the thickness of the steel arch sheet 1, and the depth of the arch sheet clamping groove is 3-5 cm, so that the steel arch sheet 1 is easy to be placed into the arch sheet clamping groove and no obvious gap appears. The front end of the arch support 2 is preferably sharp to facilitate driving into the face.
The arch bar 3 is used for being fixed on the side wall of the tunnel so that the arch sheet bracket 2 is firmly installed on the arch bar 3. For example, the arch bar 3 is a section steel, and for example, is I16 h steel. The arch springing fixing elements are used for fixing the arch springing 3 on the rock-soil body of the side wall of the tunnel, and the number of the arch springing fixing elements is suitable for enabling the arch springing 3 to bear the load of the upper structure. The arch foot fixing piece is preferably a locking foot anchor rod so as to facilitate site construction.
S2, removing footing scum of the tunnel, respectively erecting arch feet 3 on two side walls of the tunnel, and fixing the arch feet 3 on the side walls through arch foot fixing pieces. The arch foot 3 is erected from the tunnel section where the primary support has been carried out and near the tunnel section where the top cavity is present, the inner side of the arch foot 3 is preferably aligned with the tunnel excavation contour and vertically mounted, for example the arch foot 3 is of section steel, each section steel is arranged at intervals and is fixed to the side wall of the tunnel by means of at least two foot locking bolts, and the deviation of the vertical extent of each section steel is less than 2 °. After the arch springing 3 is positioned, the arch springing is fixed by uniformly beating the locking anchor rod. In order to improve the stability between the arch springes 3, at least one transverse reinforcing rib 5 is fixedly arranged between the arch springes 3 of any side wall of the tunnel. The transverse ribs 5 are preferably uniformly distributed and parallel to the tunnel axis, and the end of the transverse rib 5 remote from the tunnel face is preferably fixedly connected, for example welded, to the arch leg portion of the existing steel support 6 to improve the integrity and stability of the arch leg 3.
S3, arch sheet supports 2 are fixedly installed on arch feet 3 of two side walls of the tunnel respectively, arch sheet clamping grooves of the arch sheet supports 2 face upwards, the two arch sheet supports 2 are parallel to the axis of the tunnel, and the front ends of the arch sheet supports 2 are inserted into the tunnel face.
The tip of the arch sheet holder 2 is inserted into the tunnel face by a depth of 1m or more, for example, 1 to 2m. The rear end of the arch sheet bracket 2 is overlapped with the existing steel support 6, for example, the corresponding part of the steel support 6 in the influence range of the cavity at the top of the tunnel is drilled so as to fix the rear end of the arch sheet bracket 2 to the steel support 6. The installation height of the arch sheet support 2 is preferably located at the arch forming part of the tunnel, and the arch sheet support 2 can be fixedly installed on the top of the arch springing 3 or can be installed on the outer side of the arch springing 3. The arch sheet bracket 2 and the arch foot 3 are fixedly connected, and can be welded or bolted, and the welding connection is best in view of the fact that the bolting is not good and accurate in position.
S4, installing the steel arch sheet 1. From the one end that keeps away from the face, clear away the sediment body that the profile surface influences the installation of steel arch piece 1 of tunnel excavation, install steel arch piece 1 to the tunnel top one by one again, the outside and the tunnel excavation profile surface laminating of steel arch piece 1, in arch piece draw-in groove of arch piece support 2 is arranged respectively at the both ends of steel arch piece 1, does not leave the space between the adjacent steel arch piece 1.
The steel arch sheet 1 is moved into the tunnel in advance, at least one backfill hole 4 is reserved corresponding to at least one steel arch sheet 1 where an unstable cavity exists at the top of the tunnel, and the backfill hole 4 is preferably formed in the step S1. The steel arch sheet 1 is installed at intervals of 0.5-1.0 m, a supporting piece can be additionally arranged below the arch sheet support 2 for supporting, and the supporting piece is fixed on a rock-soil body and welded and fixed with the arch sheet support 2. The added supporting piece can be the arch springing 3, namely, the arch springing 3 can be finished in the step S2, and the construction of the arch springing 3 can be carried out in both the step S2 and the step S4.
In order to improve the integrity between the steel arch sheets 1, at least one transverse connecting rib 7 is fixedly arranged between the steel arch sheets 1, and the transverse connecting rib 7 is positioned on the inner side of the steel arch sheets 1. For example, the transverse connection rib 7 is welded and fixed to the steel arch sheet 1, and the longitudinal direction of the transverse connection rib 7 is parallel to the tunnel axis.
S5, slag discharging operation is carried out on the tunnel section in the installation range of the steel arch sheet 1, and after slag discharging is finished, the installation operation of the steel arch sheet 1 of the rest tunnel section is continued until the tunnel face.
S6, hanging a reinforcing mesh on the inner side of the arch springing 3 and spraying concrete to form a structural layer. If the gaps between the adjacent arch legs 3 are larger, dry masonry 8 can be firstly stacked at the gaps between the arch legs 3 for filling, then a reinforcing steel bar net is hung and concrete is sprayed, and the thickness of the sprayed concrete is 8-10 cm.
S7, backfilling the unstable cavity through the backfilling hole 4. The backfilling aims to improve the structure of the outer side of the steel arch sheet 1 and enable the part of the unstable cavity close to the steel arch sheet 1 to be compact as much as possible. The inner side of the steel arch sheet 1 can be sprayed with concrete or other anti-corrosion treatment. The corrosion prevention treatment of the steel arch sheet 1 may be performed in step S7 or in step S1.
The invention also provides a supporting structure of the cavity at the top of the tunnel, which is obtained according to the supporting method. Referring to fig. 1, the supporting structure for the cavity at the top of the tunnel comprises arch feet 3, arch foot fixing pieces, arch sheet supports 2 and steel arch sheets 1, wherein the arch feet 3 are used for being erected on two side walls of the tunnel, the arch foot fixing pieces are used for fixing the arch feet 3 on the side walls of the tunnel, the arch sheet supports 2 are fixedly installed on the arch feet 3, the steel arch sheets 1 are erected between the two arch sheet supports 2, the two arch sheet supports 2 are parallel to the axis of the tunnel and are preferably located at the arch forming position of the tunnel, the arch sheet supports 2 are provided with continuous arch sheet clamping grooves, the opening of each arch sheet clamping groove faces upwards or faces the inner side of the tunnel, the steel arch sheets 1 are strip-shaped steel plates bent into an arch shape, at least two steel arch sheets 1 are reserved with at least one backfill hole 4, two ends of each steel arch sheet 1 are respectively arranged in the arch sheet clamping grooves of the arch sheet supports 2, and no gap is reserved between the steel arch sheets 1 for close joint. The inner side of the arch foot 3 is a structural layer formed by hanging a reinforcing mesh and spraying concrete.
The arch 3 may be a section steel or a channel steel, or other metal member, and the arch fixing member is preferably a locking anchor rod. In order to ensure the stability of each arch leg 3, the arch legs 3 are arranged at intervals, each arch leg 3 is fixed by at least two locking anchor rods, and the deviation of the verticality of each section steel is smaller than 2 degrees. The arch sheet support 2 is a U-shaped channel steel with a U-shaped section, the front end of the channel steel is sharp, one side of the channel steel forms a U-shaped arch sheet clamping groove, and the width of the arch sheet clamping groove is larger than the thickness of the steel arch sheet 1. The arch sheet bracket 2 and the arch foot 3 are connected by welding or bolts, and the welding connection can be selected for facilitating construction. At least one transverse reinforcing rib 5 is fixedly arranged between arch feet 3 of the same side wall of the tunnel. The transverse reinforcing ribs 5 may be parallel to the tunnel axis or may be non-parallel to the tunnel axis. The transverse reinforcing ribs 5 are preferably welded with the arch springing 3, so that the construction is facilitated.
The inner side of the arch foot 3 is a structural layer formed by hanging a reinforcing mesh and spraying concrete. In order to reduce the concrete spraying amount, the space between the arch feet 3 is piled up with dry masonry 8, and the inner sides of the arch feet 3 and the dry masonry 8 are hung with reinforcing steel bars and sprayed with concrete to form a structural layer.
At least one transverse connecting rib 7 is fixedly arranged between the steel arch sheets 1, and the transverse connecting rib 7 is positioned on the inner side of the steel arch sheets 1. For ease of construction, the transverse connecting ribs 7 are welded to the steel arch sheet 1, and the length direction of the transverse connecting ribs 7 is preferably parallel to the tunnel axis.
Claims (10)
1. The tunnel top cavity supporting method is characterized in that an unstable cavity appears at the top of a tunnel close to a tunnel face during blasting excavation of a weak broken surrounding rock tunnel section, and the method is characterized in that: the support treatment method comprises the following steps:
s1, manufacturing a steel arch sheet (1), an arch sheet support (2), arch pins (3) and arch pin fixing pieces for standby, wherein the steel arch sheet (1) is a strip-shaped steel plate bent into an arch shape, and one side of the arch sheet support (2) is provided with a continuous arch sheet clamping groove;
s2, removing footing scum of the tunnel, respectively erecting arch feet (3) on two side walls of the tunnel, and fixing the arch feet (3) on the side walls through arch foot fixing pieces;
s3, arch sheet supports (2) are fixedly installed on arch feet (3) of two side walls of the tunnel respectively, arch sheet clamping grooves of the arch sheet supports (2) face upwards, the two arch sheet supports (2) are parallel to the axis of the tunnel, and the front ends of the arch sheet supports (2) are inserted into the tunnel face;
s4, starting from one end far away from the tunnel face, removing slag bodies which affect the installation of the steel arch sheets (1) on the tunnel excavation profile face, installing the steel arch sheets (1) to the top of the tunnel one by one, attaching the outer sides of the steel arch sheets (1) to the tunnel excavation profile face, respectively arranging two ends of the steel arch sheets (1) in arch sheet clamping grooves of the arch sheet supports (2), and keeping no gaps between the adjacent steel arch sheets (1); at least one backfill hole (4) is reserved corresponding to at least one steel arch sheet (1) at the position where an unstable cavity exists at the top of the tunnel;
s5, slag discharging operation is carried out on tunnel sections in the installation range of the steel arch sheet (1), and after slag discharging is finished, the installation operation of the steel arch sheet (1) of the rest tunnel sections is continued until the tunnel face;
s6, hanging a reinforcing mesh on the inner side of the arch springing (3) and spraying concrete to form a structural layer; the gaps between adjacent arch legs (3) are filled by stacking dry masonry (8), then a reinforcing mesh is hung and concrete is sprayed;
s7, backfilling the unstable cavity through the backfilling hole (4).
2. The tunnel roof cavity support method of claim 1, wherein: in S1, the arch sheet bracket (2) is a U-shaped channel steel with a U-shaped section, the front end of the channel steel is sharp, one side of the channel steel is provided with a U-shaped arch sheet clamping groove, and the width of the arch sheet clamping groove is larger than the thickness of the steel arch sheet (1); the arch foot (3) is shaped steel, and the arch foot fixing piece is a locking foot anchor rod.
3. The tunnel roof cavity support method of claim 2, wherein: in S1, the thickness of the steel arch sheet (1) is 1-2 cm, and the width is 20-50 cm; the width of the arch sheet clamping groove of the arch sheet bracket (2) is 1.5-2.0 times of the thickness of the steel arch sheet (1), and the depth of the arch sheet clamping groove is 3-5 cm; the arch leg (3) is I16I-steel.
4. The tunnel roof cavity support method of claim 1, wherein: in S2, arch springing (3) are shaped steel, every shaped steel interval arrangement and be fixed in the lateral wall of tunnel through two piece at least lock foot stock, and the deviation of the straightness of verticality of every shaped steel is all less than 2.
5. The tunnel roof cavity support method of claim 1, wherein: in S2, at least one transverse reinforcing rib (5) is fixedly arranged between arch legs (3) of any side wall of the tunnel, and one end, far away from the tunnel face, of the transverse reinforcing rib (5) is fixedly connected with an arch leg part of an existing steel support (6).
6. The tunnel roof cavity support method of claim 1, wherein: in S3, the arch sheet support (2) is welded or connected with the arch foot (3) through bolts, and the front end of the arch sheet support (2) is inserted into the tunnel face for 1-2 m.
7. The tunnel roof cavity support method of any one of claims 1-6, wherein: s4, at least one transverse connecting rib (7) is fixedly arranged between the steel arch sheets (1), and the transverse connecting rib (7) is positioned on the inner side of the steel arch sheets (1).
8. The tunnel roof cavity support method of claim 7, wherein: and S4, welding and fixing the transverse connecting ribs (7) on the steel arch sheet (1), wherein the length direction of the transverse connecting ribs (7) is parallel to the axis of the tunnel.
9. The tunnel roof cavity support method of any one of claims 1-6, wherein: in S6, the thickness of the sprayed concrete at the position between the adjacent arch legs (3) is 8-10 cm.
10. The tunnel roof cavity support method of any one of claims 1-6, wherein: and S7, backfilling the unstable cavity with dry sand through the backfilling hole (4).
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