CN112127911B - Primary support invasion limit arch changing method for soft-hard interbedded surrounding rock tunnel - Google Patents
Primary support invasion limit arch changing method for soft-hard interbedded surrounding rock tunnel Download PDFInfo
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- 239000011435 rock Substances 0.000 title claims abstract description 131
- 230000009545 invasion Effects 0.000 title claims abstract description 36
- 238000000034 method Methods 0.000 title claims abstract description 31
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 179
- 239000010959 steel Substances 0.000 claims abstract description 179
- 239000004567 concrete Substances 0.000 claims abstract description 25
- 238000010276 construction Methods 0.000 claims abstract description 21
- 238000005507 spraying Methods 0.000 claims abstract description 20
- 230000002787 reinforcement Effects 0.000 claims abstract description 6
- 238000004873 anchoring Methods 0.000 claims abstract description 4
- 239000002002 slurry Substances 0.000 claims description 7
- 238000003466 welding Methods 0.000 claims description 7
- 239000011378 shotcrete Substances 0.000 claims description 4
- 239000004568 cement Substances 0.000 claims description 3
- 235000019353 potassium silicate Nutrition 0.000 claims description 3
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 3
- 229910001294 Reinforcing steel Inorganic materials 0.000 claims description 2
- 230000002093 peripheral effect Effects 0.000 abstract description 5
- 238000009412 basement excavation Methods 0.000 description 4
- 238000012544 monitoring process Methods 0.000 description 3
- 230000005641 tunneling Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 239000011440 grout Substances 0.000 description 2
- 239000011229 interlayer Substances 0.000 description 2
- 230000003014 reinforcing effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011083 cement mortar Substances 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000009191 jumping Effects 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 239000000758 substrate Substances 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
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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
- E21D11/14—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 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
- E21D11/22—Clamps or other yieldable means for interconnecting adjacent arch members either rigidly, or allowing arch member parts to slide when subjected to excessive pressure
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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
- E21D11/28—Longitudinal struts, i.e. longitudinal connections between adjoining arches
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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
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- 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)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Civil Engineering (AREA)
- Lining And Supports For Tunnels (AREA)
Abstract
The invention discloses a soft-hard interbedded surrounding rock tunnel primary support invasion limit arch replacement construction method, which comprises the following steps of: 1) determining the cross section of the tunnel with the limit intrusion phenomenon, and selecting three steel arches at the limit intrusion phenomenon position of the tunnel as arch changing objects; supporting surrounding rocks and supporting three steel arches; 2) radial anchor pipe grouting reinforcement and anchor pipe tail end anchoring are carried out on soft surrounding rocks corresponding to the three steel arches; 3) assembling a steel arch frame; 4) changing arches of harder surrounding rock areas; 5) changing arches of the weak surrounding rock areas; 6) and removing the temporary support, paving the force-bearing steel beams, and spraying concrete to the three steel arch frames integrally. The invention utilizes the self bearing capacity of the steel arch frame, greatly reduces the invasion limit of the weak part of the surrounding rock of the tunnel, and effectively controls the vault settlement and the peripheral convergence deformation of the surrounding rock. The method is convenient to operate, and can improve the construction efficiency and safety of tunnel arch replacement.
Description
Technical Field
The invention relates to a limit-invasion arch-changing method for primary support of a soft-hard interbedded surrounding rock tunnel.
Background
In the excavation process of the tunnel, particularly a deep-buried tunnel, non-horizontal soft and hard interbedded surrounding rocks are penetrated sometimes. The soft and hard surrounding rock often has unfavorable geological characteristics such as uneven distribution of the soft and hard surrounding rock, complex engineering geological conditions, a fractured and broken zone, difficulty in exploration of irregularly distributed fractures and the like, so that the problems that the actual requirements cannot be met by design and the like occur, and the phenomenon of local limit invasion of the tunnel is further caused. The tunnel invasion limit usually means that the vault of the tunnel is subsided or the peripheral convergence is too large in the primary support stage, so that the tunnel invades into the secondary lining limit, and if the phenomenon is not processed and the secondary lining is directly carried out, in order to ensure the minimum thickness of the secondary lining, the secondary lining can be invaded into the tunnel building limit. When the tunnel has an invasion limit phenomenon, the arch replacement is usually performed, namely the replacement of a primary supported steel arch is performed, the excavation is stopped firstly, then the arch replacement is performed on an invasion limit section, the specific operation is that other supports are applied to replace the stress of the original steel arch, then the surrounding rock is grouted, then the original steel arch is dismantled and the tunnel is expanded, and finally a new supporting structure is applied.
The intrusion limit of the soft-hard interbed surrounding rock can be reflected by monitoring and measuring data, for the condition of the soft-hard interbed surrounding rock, the monitoring and measuring data generally reflect that one steel arch truss has larger settlement and exceeds an allowable settlement value or a convergence value, while two adjacent steel arch trusses do not generate large settlement or convergence, and the intrusion limit is named as the intrusion limit of the soft-hard interbed surrounding rock. And there are two problems: (1) due to the complexity of engineering geological conditions of the soft and hard interbedded surrounding rocks, the invasion limit often appears in the soft and weak surrounding rock sections, the invasion limit does not appear in the harder surrounding rock sections, and the jumping invasion limit is generated; (2) the traditional arch changing mode mainly adopts a single steel arch to support top surrounding rocks, for soft and hard interbedded surrounding rocks, the required bearing capacity cannot be completely met by only adopting the single steel arch at a soft and weak layer, and invasion limit may occur due to integral settlement.
Disclosure of Invention
In order to solve the technical problems, the invention provides a soft-hard interbedded surrounding rock tunnel primary support invasion limit arch changing method which can utilize the self bearing capacity of a steel arch frame, greatly reduce the invasion limit of the weak part of the surrounding rock of the tunnel and effectively control the surrounding rock vault settlement and the peripheral convergence deformation, is convenient to operate and can improve the construction efficiency and the safety of the tunnel arch changing.
The technical scheme adopted by the invention is as follows: a primary support invasion limit arch changing method for a soft-hard interbedded surrounding rock tunnel comprises the following steps:
1) determining the cross section of the tunnel with the limit intrusion phenomenon, and selecting three steel arches at the limit intrusion phenomenon position of the tunnel as arch changing objects; i-shaped steel is used as temporary support to support surrounding rock at the center between two adjacent steel arches in the three steel arches;
2) radial anchor pipe grouting reinforcement and anchor pipe tail end anchoring are carried out on soft surrounding rocks corresponding to the three steel arches;
3) assembling a new steel arch, and arranging connecting devices with anchor pipes on two sides of the new steel arch; axially arranging a steel arch connecting plate at the center of each new steel arch, and reserving bolt holes on the steel arch connecting plates;
4) the method comprises the steps of replacing an arch of a relatively hard surrounding rock area which is not invaded and limited in surrounding rocks corresponding to three steel arch frames, dismantling the arch crown of the steel arch frame, laying a steel bar mesh on the inner wall of the surrounding rock after dismantling is finished, carrying out concrete spraying construction on the place where the steel bar mesh is laid, and laying a new steel arch frame at the position where the arch crown of the steel arch frame is dismantled after the concrete spraying construction is finished; after the arch change of the hard surrounding rock area without limit invasion is finished, the arch change is carried out on the other hard surrounding rock area in the surrounding rock corresponding to the three steel arch frames until all the hard surrounding rock areas in the surrounding rock corresponding to the three steel arch frames are changed;
5) the method comprises the following steps of (1) changing an arch of a soft surrounding rock area in surrounding rocks corresponding to three steel arch frames, chiseling out primary concrete, then dismantling a top steel arch frame, paving a reinforcing steel bar net piece on the inner wall of the surrounding rocks, carrying out primary concrete spraying construction, after the concrete spraying construction is finished, erecting a new steel arch frame at the position of the top steel arch frame, and welding and connecting the new steel arch frame with an anchor rod; after the arch change of the soft surrounding rock area is finished, changing the arch of the other soft surrounding rock area in the surrounding rock corresponding to the three steel arches until all the soft surrounding rock areas in the surrounding rock corresponding to the three steel arches are changed;
6) and (5) dismantling the temporary support, laying a bearing steel beam, and performing concrete spraying construction on the three steel arch frames integrally.
In the soft and hard interbedded surrounding rock tunnel primary support invasion limit arch changing method, in the step 2), when grouting reinforcement is carried out on soft and weak surrounding rocks, single-pipe grouting is adopted to improve the stability of the surrounding rocks, anchor pipe grouting is adopted in a grouting mode, and anchor pipes are driven to harder surrounding rock strata inside the surrounding rocks.
In the soft and hard interbedded surrounding rock tunnel primary support intrusion limit arch changing method, in the step 2), a steel perforated pipe with the inner diameter of 90mm and the outer diameter of 100mm is adopted as a grouting pipe; the grouting holes are arranged annularly.
In the method for limit arch replacement by primary support intrusion of the soft-hard interbedded surrounding rock tunnel, in the step 2), the grouting slurry adopts a weight ratio of cement slurry to water glass slurry of 1: 1, the grouting pressure is 0.3-1.0 Mpa, and the condition for stopping grouting is as follows: the total grouting amount and the grouting pressure reach the design requirements, or the total grouting amount reaches 80% of the design value and the grouting pressure exceeds the design value.
In the soft and hard interbedded surrounding rock tunnel primary support invasion limit arch changing method, in the step 2), the designed grouting pressure value is 1.0 Mpa.
In the soft and hard interbedded surrounding rock tunnel primary support invasion limit arch changing method, in the step 3), the new steel arch comprises a plurality of steel arch units, and the plurality of steel arch units are sequentially connected into a tunnel section shape; two ends of the new steel arch center are respectively connected with a steel base plate, and the steel base plates are horizontally arranged.
In the soft and hard interbedded surrounding rock tunnel primary support intrusion limit arch changing method, in the steps 4), 5) and 6), the strength of the sprayed concrete is C25-C30 during the concrete spraying construction.
In the soft and hard interbedded surrounding rock tunnel primary support invasion limit arch changing method, in the step 6), the bearing steel beams are I-shaped steel, the steel arch units at the opposite ends of the two adjacent new steel arches are connected through one bearing steel beam, and the bearing steel beam is connected at the midpoint of the steel arch unit.
Compared with the prior art, the invention has the beneficial effects that: the method is convenient to operate, and can improve the construction efficiency and safety of tunnel arch replacement. Aiming at the problem that the bearing capacity of soft rock in soft and hard interbedded surrounding rock is insufficient, the substrate cannot provide enough bearing capacity, stress redistribution is carried out by replacing the arches of the peripheral steel arches, and the surrounding rock stress originally borne by the steel arch at the invasion limit position is borne by two steel arches with good surrounding rock conditions at two sides and one steel arch with poor surrounding rock conditions at the middle part; the invention utilizes the self bearing capacity of the steel arch frame, greatly reduces the invasion limit of the weak part of the surrounding rock of the tunnel, and effectively controls the vault settlement and the peripheral convergence deformation of the surrounding rock.
Drawings
FIG. 1 is a flow chart of arch changing of a soft-hard inter-layer tunnel according to the present invention;
FIG. 2 is a view of a tunnel section and radial conduit layout of the present invention;
FIG. 3 is a schematic view of a tunneling sequence of the present invention;
FIG. 4 is a schematic view of an upper section steel support structure according to the present invention;
FIG. 5 is a schematic view of a full-section steel support structure according to the present invention;
FIG. 6 is a schematic structural view of a steel arch according to the present invention;
FIG. 7 is a schematic view of a node A of FIG. 6 according to the present invention;
FIG. 8 is a schematic view of a schematic representation of the node B of FIG. 6 according to the present invention;
FIG. 9 is a schematic view of a schematic representation of node C of FIG. 6 according to the present invention;
FIG. 10 is a schematic view of the arrangement of the mesh reinforcement of the present invention;
FIG. 11 is a schematic diagram of a soft-hard inter-layer arch exchange sequence according to the present invention;
in the figure:
2-1 of primary support, 2-2 of steel arch, 2-3 of secondary lining, 2-4 of radial guide pipe and 2-5 of inverted arch;
3-1, annularly excavating an arch part, 3-2, excavating core soil, 3-3, excavating a middle groove of a lower step, 3-4, excavating the left side of the lower step, and 3-5, excavating the right side of the lower step;
4-1 of transverse support I, 4-2 of vertical support I, and 4-3 of oblique support I; 5-1 of a transverse support II, 5-2 of a vertical support II, and 5-3 of an oblique support II;
6-1, a steel arch frame unit; a, connecting the steel arch frame units; b, connecting the bearing steel beam and the steel arch frame; c, the contact part of the steel arch frame and the ground
7-1, connecting a steel plate I; 7-2, stiffening angle steel I; 7-3, high-strength bolts; 7-4, a nut;
8-1, stiffening angle steel II; 8-2, connecting a steel plate II; 8-3, a bearing steel beam;
9-1, connecting a steel plate III; 9-2, stiffening angle steel III;
10-1: longitudinal ribs; 10-2: and (5) ring ribs.
11-1 parts of a steel arch at a harder surrounding rock, 11-2 parts of a steel arch at a softer surrounding rock and 11-3 parts of a temporary support.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings.
Examples
In this embodiment, the tunnel adopts a step-by-step excavation method, the excavation section and the radial conduit arrangement are shown in fig. 2, and the tunneling sequence diagram is shown in fig. 3. The tunnel is a soft-hard interbedded tunnel, and when monitoring measurement is carried out, the situation that settlement or convergence of a certain section of the tunnel is too large and settlement and convergence of an adjacent section of the tunnel are small is monitored at any time, and in the face of the situation, the tunnel needs to be arched. As shown in fig. 1, the primary support invasion limit arch changing method for the soft-hard interbedded surrounding rock tunnel includes the following steps:
the method comprises the following steps: determining the cross section of the tunnel with the limit intrusion phenomenon, and selecting three steel arches at the limit intrusion phenomenon position of the tunnel as arch changing objects; i-shaped steel is used as temporary support to support surrounding rock between two adjacent steel arches in the three steel arches;
the support of the surrounding rock is divided into two types, one type is an upper section temporary steel support, and the support is used for excavating only an upper section tunnel and causing invasion limit, as shown in figure 4. The erection steps are as follows: firstly, erecting a vertical support I4-2 to enable the length of the vertical support I4-2 to be consistent with the height of the inner contour of the tunnel, and chiseling top surrounding rock by using an air pick before erecting the vertical support I4-2 due to the surrounding rock sinking condition. After the vertical support I4-2 is erected, transverse support I4-1 is erected, and the transverse support I4-1 and the vertical support 4-2 are connected through high-strength bolts. Then, the bottom oblique support I4-3 is erected, and is connected with the vertical support I4-2 by high-strength bolts. And finally, obliquely supporting and erecting the top, and connecting the top with a vertical support I4-2 by adopting a high-strength bolt.
The second type is a full-face temporary steel support, which is used when the tunnel excavated from the full-face has an invasion limit, as shown in fig. 5. The erection steps are as follows: firstly, two vertical supports II 5-2 are erected, then two transverse supports II 5-1 are erected, the transverse steel supports II 5-1 and the vertical supports II 5-2 are connected through high-strength bolts, two ends of the transverse steel supports II 5-1 are in contact with surrounding rocks, and the surrounding rocks are eroded to limit positions, so that air picks which cannot be erected are used for chiseling. Then an oblique support II 5-3 at the lower part is erected, the upper end of the oblique support II is connected to the vertical support II 5-2 through a high-strength bolt, finally the oblique support at the top is erected, the lower end of the oblique support II is connected to the vertical support II 5-2 through the high-strength bolt, and surrounding rock at the upper end of the oblique support II also needs to be chiseled firstly. In this embodiment, the position of the temporary steel support is located at the center of two adjacent steel arches, as shown at 11-3 in fig. 11.
Step two: and (4) performing radial anchor pipe grouting on the weak surrounding rock.
Single-pipe grouting is adopted to improve the stability of surrounding rocks, and the length of a guide pipe is designed to be 5 m. And the grouting mode adopts an anchor pipe for grouting, and the anchor pipe needs to be punched into a harder surrounding rock stratum inside the surrounding rock to complete preposed work for anchoring the tail end of the anchor pipe.
As shown in FIG. 2, the grouting pipe of the grouting method is a steel flower pipe with an inner wall radius of 45mm and an outer wall radius of 50 mm. The arrangement of the grouting pipes is in an annular arrangement, and the distance between the grouting pipes is determined based on the diffusion diameter of cement mortar.
The grouting manner adopts a grouting manner that the weight ratio of cement grout to water glass grout is 1: 1, grouting pressure is 0.3-1.0 Mpa, the termination condition is that the total grouting amount and the grouting pressure reach the design requirement or reach 80% of the design value, the grouting pressure exceeds the design value, and the design final pressure is 1.0Mpa generally.
Step three: assembling a new steel arch, and arranging connecting devices with anchor pipes on two sides of the new steel arch; and a steel arch connecting plate is axially arranged at the center of each new steel arch, and a bolt hole is reserved on the steel arch connecting plate.
Before replacing the steel arch, the new steel arch needs to be pre-assembled, so that the problem that the steel arch cannot be assembled in a hole due to overlarge production error is avoided. As shown in fig. 6, the steel arch has a tunnel cross-sectional shape formed by splicing seven steel arch units, and support plates C for increasing the stress area are arranged on the contact surfaces of the two ends of the new steel arch and the ground. And devices connected with the anchor pipe are arranged on two sides of the new steel arch frame, so that the device is conveniently connected with the vault grouting anchor pipe in a welding manner. And a steel arch connecting plate is axially arranged at the center of each steel arch unit, and a high-strength bolt hole is reserved on the plate, so that the component force steel arch is conveniently laid. The contact surface of the bottom steel arch unit and the ground is provided with a support plate C to improve the stress area of the ground and reduce the integral settlement caused by insufficient bearing capacity.
Step four: and (4) performing arch change on a harder surrounding rock area (an uninjured surrounding rock area) of the tunnel.
After the grouting slurry in the step 2) is solidified, one hard surrounding rock area which is not invaded and limited in the surrounding rocks corresponding to the three steel arches is changed. When the arch is changed, firstly, redundant surrounding rocks in the arch crown area are chiseled by using an air pick, then, an arch crown steel arch frame is removed, after the removal is completed, a steel bar mesh is laid on the inner wall of the surrounding rocks, the steel bar mesh is shown in figure 10, concrete spraying construction is carried out on the place where the steel bar mesh is laid, the concrete spraying is C25 or C30 concrete, and the thickness is determined by design. And after the concrete spraying construction is finished, laying a new steel arch frame at the arch crown removing position. And after the arch change of the area of the harder surrounding rock without limit invasion is finished, changing the arch of the other area of the harder surrounding rock in the surrounding rock corresponding to the three steel arches until all areas of the harder surrounding rock in the surrounding rock corresponding to the three steel arches are changed. As shown in figure 11, the steel arch 11-1 at the harder surrounding rock is arched in a tunneling direction.
Step five: and (4) performing arch change on the weak surrounding rock area (invasion surrounding rock area) of the tunnel.
And after the arch change of the harder surrounding rock area of the tunnel is finished, starting to change the arch of one soft surrounding rock area in the surrounding rocks corresponding to the three steel arches. When the arch is changed, firstly, a pneumatic pick is used for chiseling redundant surrounding rocks in the arch crown area, then, the arch crown steel arch center is dismantled, reinforcing mesh pieces are laid on the inner walls of the surrounding rocks, the reinforcing mesh pieces are shown in figure 10, the primary concrete spraying construction is carried out, the sprayed concrete is C25 or C30 concrete, and the thickness is determined by design. After the construction of the sprayed concrete is finished, a new steel arch is erected at the position of the top steel arch, and the steel arch and the anchor pipe are connected in a welding mode. After the arch change of the soft surrounding rock area is finished, changing the arch of the other soft surrounding rock area in the surrounding rock corresponding to the three steel arches until all the soft surrounding rock areas in the surrounding rock corresponding to the three steel arches are changed;
step six: and dismantling the temporary supports, paving the force-bearing steel beams, and performing concrete spraying construction on the three steel arch frames integrally.
And after the arch change of the weak surrounding rock area is completed, dismantling the temporary support. The purpose of dismantling the temporary support is to avoid the temporary support from obstructing the laying of the axial force bearing steel beam, and the force bearing steel beam is laid after the temporary steel support at the periphery of the inner contour is dismantled. The connection mode of the two ends of the bearing steel beam and the steel arch is shown in fig. 8, the bearing steel beam is made of i-steel, the steel arch units at the opposite ends of the two adjacent new steel arches are connected through one bearing steel beam, and the bearing steel beam is connected to the middle point of the steel arch unit. The high-strength bolt connection is mainly adopted, when the high-strength bolt cannot be adopted, welding treatment is adopted, and the welding mode is full welding. And after the bearing steel beam is laid, comprehensively dismantling the temporary steel support. And after the dismantling is finished, integrally spraying concrete to the group of steel arches, wherein the concrete spraying adopts C25 or C30 concrete, and the thickness is determined by design.
Claims (8)
1. A primary support invasion limit arch changing method for a soft-hard interbedded surrounding rock tunnel comprises the following steps:
1) determining the cross section of the tunnel with the limit intrusion phenomenon, and selecting three steel arches at the limit intrusion phenomenon position of the tunnel as arch changing objects; i-shaped steel is used as temporary support to support surrounding rock at the center between two adjacent steel arches in the three steel arches;
2) radial anchor pipe grouting reinforcement and anchor pipe tail end anchoring are carried out on soft surrounding rocks corresponding to the three steel arches;
3) assembling a new steel arch, and arranging connecting devices with anchor pipes on two sides of the new steel arch; axially arranging a steel arch connecting plate at the center of each new steel arch, and reserving bolt holes on the steel arch connecting plates;
4) the method comprises the steps of replacing an arch of a relatively hard surrounding rock area which is not invaded and limited in surrounding rocks corresponding to three steel arch frames, dismantling the arch crown of the steel arch frame, laying a steel bar mesh on the inner wall of the surrounding rock after dismantling is finished, carrying out concrete spraying construction on the place where the steel bar mesh is laid, and laying a new steel arch frame at the position where the arch crown of the steel arch frame is dismantled after the concrete spraying construction is finished; after the arch change of the hard surrounding rock area without limit invasion is finished, the arch change is carried out on the other hard surrounding rock area in the surrounding rock corresponding to the three steel arch frames until all the hard surrounding rock areas in the surrounding rock corresponding to the three steel arch frames are changed;
5) the method comprises the following steps of (1) changing an arch of a soft surrounding rock area in surrounding rocks corresponding to three steel arch frames, chiseling out primary concrete, then dismantling a top steel arch frame, paving a reinforcing steel bar net piece on the inner wall of the surrounding rocks, carrying out primary concrete spraying construction, after the concrete spraying construction is finished, erecting a new steel arch frame at the position of the top steel arch frame, and welding and connecting the new steel arch frame with an anchor rod; after the arch change of the soft surrounding rock area is finished, changing the arch of the other soft surrounding rock area in the surrounding rock corresponding to the three steel arches until all the soft surrounding rock areas in the surrounding rock corresponding to the three steel arches are changed;
6) and (5) dismantling the temporary support, laying a bearing steel beam, and performing concrete spraying construction on the three steel arch frames integrally.
2. The primary support invasion limit arch changing method for the soft and hard interbedded surrounding rock tunnel according to claim 1, wherein in the step 2), when grouting reinforcement is performed on the soft and weak surrounding rock, single-pipe grouting is adopted to improve the stability of the surrounding rock, and anchor pipe grouting is adopted in a grouting mode, and the anchor pipe is drilled into a harder surrounding rock stratum inside the surrounding rock.
3. The primary support invasion limit arch changing method for the soft and hard interbedded surrounding rock tunnel according to claim 2, wherein in the step 2), a steel perforated pipe with the inner diameter of 90mm and the outer diameter of 100mm is adopted as the grouting pipe; the grouting holes are arranged annularly.
4. The primary support invasion limit arch changing method for the soft and hard interbedded surrounding rock tunnel according to claim 2, wherein in the step 2), the grouting slurry is prepared by mixing cement slurry and water glass slurry in a weight ratio of 1: 1, the grouting pressure is 0.3-1.0 Mpa, and the condition for stopping grouting is as follows: the total grouting amount and the grouting pressure reach the design requirements, or the total grouting amount reaches 80% of the design value and the grouting pressure exceeds the design value.
5. The primary support invasion limit arch changing method for the soft and hard interbedded surrounding rock tunnel according to claim 4, wherein the designed grouting pressure value in the step 2) is 1.0 MPa.
6. The primary support invasion limit arch changing method for the soft and hard interbedded surrounding rock tunnel according to claim 1, wherein in the step 3), the new steel arch comprises a plurality of steel arch units which are sequentially connected into a tunnel section shape; two ends of the new steel arch center are respectively connected with a steel base plate, and the steel base plates are horizontally arranged.
7. The method for limiting primary support invasion and arch change of the soft and hard interbedded surrounding rock tunnel according to claim 1, wherein in the steps 4), 5) and 6), the strength of the sprayed concrete during the concrete spraying construction is C25-C30.
8. The primary support invasion limiting and arch changing method for the soft and hard interbedded surrounding rock tunnel according to claim 1, wherein in the step 6), the bearing steel beams are i-shaped steel, the steel arch units at the opposite ends of the two adjacent new steel arches are connected through one bearing steel beam, and the bearing steel beam is connected at the middle point of the new steel arch unit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011173112.9A CN112127911B (en) | 2020-10-28 | 2020-10-28 | Primary support invasion limit arch changing method for soft-hard interbedded surrounding rock tunnel |
Applications Claiming Priority (1)
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| SU1712617A1 (en) * | 1990-02-15 | 1992-02-15 | Московский Горный Институт | Method of working support |
| JP2973852B2 (en) * | 1995-01-26 | 1999-11-08 | 鹿島建設株式会社 | Construction method and split segment for large section tunnel |
| CN102678134B (en) * | 2012-05-18 | 2014-12-10 | 中铁十二局集团第二工程有限公司 | Collapse and sink intrusion limit construction method for treating wind accumulated sand loess tunnel through stride shed pipe |
| CN102733827B (en) * | 2012-06-29 | 2014-09-10 | 湖南省交通规划勘察设计院 | Tunnel arch exchanging construction method and construction structure in tunnel arch exchanging construction |
| CN206668276U (en) * | 2017-03-09 | 2017-11-24 | 洛阳理工学院 | Arch device is changed in the movement that a kind of tunnel initial support invades limit section |
| CN106869960B (en) * | 2017-03-09 | 2019-06-04 | 洛阳理工学院 | It is a kind of using tunnel initial support invade limit section movement change arch device carry out changing arch method |
| CN108561156B (en) * | 2018-04-30 | 2024-03-19 | 安徽省公路桥梁工程有限公司 | Separated tunnel arch-changing supporting structure and construction method thereof |
| CN111779510B (en) * | 2020-08-05 | 2022-03-25 | 湖南科技大学 | Primary support invasion limit arch changing method for high liquid limit red clay surrounding rock tunnel |
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