CN110566253B - Reinforcing structure of small-clear-distance tunnel and construction method - Google Patents
Reinforcing structure of small-clear-distance tunnel and construction method Download PDFInfo
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- CN110566253B CN110566253B CN201910649883.1A CN201910649883A CN110566253B CN 110566253 B CN110566253 B CN 110566253B CN 201910649883 A CN201910649883 A CN 201910649883A CN 110566253 B CN110566253 B CN 110566253B
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- rock column
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- 238000010276 construction Methods 0.000 title claims abstract description 26
- 230000003014 reinforcing effect Effects 0.000 title claims abstract description 15
- 239000011435 rock Substances 0.000 claims abstract description 116
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 48
- 239000010959 steel Substances 0.000 claims abstract description 48
- 230000002787 reinforcement Effects 0.000 claims description 17
- 238000004873 anchoring Methods 0.000 claims description 13
- 238000009412 basement excavation Methods 0.000 claims description 13
- 238000005422 blasting Methods 0.000 claims description 12
- 230000006835 compression Effects 0.000 claims description 5
- 238000007906 compression Methods 0.000 claims description 5
- 238000009434 installation Methods 0.000 claims description 5
- 230000000149 penetrating effect Effects 0.000 claims description 5
- 238000000034 method Methods 0.000 claims description 4
- 238000005507 spraying Methods 0.000 claims description 3
- 238000006073 displacement reaction Methods 0.000 description 10
- 230000000694 effects Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 239000002002 slurry Substances 0.000 description 2
- 230000005641 tunneling Effects 0.000 description 2
- 206010035148 Plague Diseases 0.000 description 1
- 241000607479 Yersinia pestis Species 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000013467 fragmentation Methods 0.000 description 1
- 238000006062 fragmentation reaction Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
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- E—FIXED CONSTRUCTIONS
- E21—EARTH 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
- E21D11/14—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
- E21D20/00—Setting anchoring-bolts
-
- 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
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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)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Structural Engineering (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Environmental & Geological Engineering (AREA)
- Lining And Supports For Tunnels (AREA)
Abstract
The invention discloses a reinforcing structure of a small clear-distance tunnel, which comprises a hollow grouting anchor rod, a prestressed anchor rod and a conduit grouting anchor rod which are arranged on a middle rock column of the small clear-distance tunnel, wherein the uniform ends of the hollow grouting anchor rod and the conduit grouting anchor rod are inserted into the middle rock column, and the two ends of the prestressed anchor rod are respectively positioned in two tunnels of the small clear-distance tunnel; the two adjacent hollow grouting anchor rods or conduit grouting anchor rods are sleeved with the same steel sheet, the end parts of the hollow grouting anchor rods and the conduit grouting anchor rods, which are positioned in the tunnel, are provided with first nuts, and the two ends of the prestressed anchor rods are respectively provided with second nuts. A construction method for small clear distance tunnel includes such steps as installing hollow grouting anchor rod and catheter grouting anchor rod in the tunnel, and installing prestressed anchor rod. The invention improves the stability of the middle rock pillar in the small clear distance tunnel.
Description
Technical Field
The invention relates to the technical field of geotechnical engineering, in particular to a reinforcing structure of a small-clear-distance tunnel and a construction method.
Background
The stability of the small clear distance tunnel mainly depends on the stability of a middle rock pillar, but the poor stability of the middle rock pillar and easiness in cracking are the main problems which plague the construction of the small clear distance tunnel, most of tunnels are constructed by adopting sequential tunneling, the stability of the prior tunnel is always influenced by the excavation blasting of the subsequent tunnel, and the problems of surrounding rock collapse and uncontrolled excavation section can be even caused.
Disclosure of Invention
The invention aims to provide a reinforcing structure of a small-clearance tunnel and a construction method thereof, which are used for solving the problems in the prior art, reducing the vertical displacement and the transverse displacement of a middle rock column, improving the stability of the middle rock column in the small-clearance tunnel, reducing the disturbance of blasting excavation on the excavated section of the tunnel and guaranteeing the safety of tunnel construction.
In order to achieve the above object, the present invention provides the following solutions: the invention provides a reinforcing structure of a small clear distance tunnel, which comprises a plurality of hollow grouting anchor rods, a plurality of prestressed anchor rods and a plurality of conduit grouting anchor rods, wherein the hollow grouting anchor rods are arranged on a middle rock column of the small clear distance tunnel; the two adjacent hollow grouting anchor rods or the conduit grouting anchor rods are sleeved with the same steel sheet, the hollow grouting anchor rods and the conduit grouting anchor rods are positioned at the end parts in the tunnels and are provided with first nuts, the steel sheet is positioned between the first nuts and the side walls of the middle rock columns, and the two ends of the prestressed anchor rods are respectively provided with second nuts.
Preferably, the hollow grouting anchor rod, the prestressed anchor rod and the conduit grouting anchor rod are respectively and uniformly distributed in a plurality of rows, and two horizontally adjacent hollow grouting anchor rods or conduit grouting anchor rods are respectively sleeved with the same steel sheet; the middle of the steel sheet is a protruding portion, two sides of the steel sheet are flat portions, a through hole used for penetrating through the hollow grouting anchor rod, the prestressed anchor rod or the conduit grouting anchor rod is formed in the flat portions, and two adjacent steel sheets are opposite in installation direction and buckled together.
Preferably, the thickness of the flat portion is 5mm, and the thickness of the protruding portion is 10mm.
Preferably, the hollow grouting anchor rod is arranged in the area from the top end of the middle rock column to 3/5 of the height of the middle rock column, the conduit grouting anchor rod is arranged in the area from the bottom end of the middle rock column to 2/5 of the height of the middle rock column, and the prestress anchor rod is arranged in the area from 2/5 of the height of the middle rock column to 3/5 of the height of the middle rock column.
Preferably, one end of the second nut is provided with a circular ring, four reinforcing ribs are arranged on the outer wall of the second nut, and the reinforcing ribs are fixedly connected with the circular ring.
Preferably, the hollow grouting anchor rod is fixedly connected with surrounding rock through slurry, the hollow grouting anchor rod and the surrounding rock form a combined reinforcing body, and the conduit anchor rod and surrounding rock form a compression belt.
Preferably, the hollow grouting anchor rod is inclined upwards, the prestressed anchor rod is horizontal, and the conduit anchor rod is inclined downwards.
The invention also provides a construction method of the small clear distance tunnel, which comprises the following steps:
(1) Excavating a small clear distance tunnel in a weak crushing area, blasting surrounding rock by adopting smooth blasting, controlling excavation footage according to 0.5m, performing supporting construction in each cycle, and grouting the lower part of a middle rock column in a preceding tunnel by adopting a guide pipe grouting anchor rod after the preceding tunnel of the small clear distance tunnel is excavated, wherein the anchoring range is from the bottom end of the middle rock column to 2/5 height; the upper part of the middle rock column is reinforced by adopting a hollow grouting anchor rod, the anchoring range is from the position of the middle rock column at 3/5 height from the ground to the top end of the middle rock column, the conduit grouting anchor rod and the hollow grouting anchor rod are fixed by installing horizontal two-hole steel sheets after being installed, the two-hole steel sheets are positively and negatively connected, each steel sheet is connected with the conduit grouting anchor rods or the hollow grouting anchor rods of two adjacent same horizontal lines, the conduit grouting anchor rods or the hollow grouting anchor rods of the same horizontal lines are fixed by using first nuts after being spliced, so that the conduit grouting anchor rods or the hollow grouting anchor rods of the same horizontal lines are connected into a whole, and grouting is performed;
(2) Excavating a backward tunnel, and grouting the lower part of a middle rock column in the backward tunnel by adopting a conduit grouting anchor rod when the backward tunnel is excavated, wherein the anchoring range is from the bottom end of the middle rock column to the position of 2/5 of the height; the upper part of the middle rock column in the backward tunnel is reinforced by adopting a hollow grouting anchor rod, the anchoring range is from the position of 3/5 of the middle rock column to the ground to the top end of the middle rock column, the conduit grouting anchor rod and the hollow grouting anchor rod are fixed by installing horizontal two-hole steel sheets after being installed, the two-hole steel sheets are positively and negatively connected, each steel sheet is connected with the conduit grouting anchor rod or the hollow grouting anchor rod of two adjacent same horizontal lines, and the conduit grouting anchor rod or the hollow grouting anchor rod of the same horizontal line are fixed by using a first screw cap after being spliced, so that the conduit grouting anchor rod or the hollow grouting anchor rod of the same horizontal line are connected into a whole, and grouting and concrete spraying are carried out;
(3) Installing a pre-stress anchor rod in the middle of the middle rock column, grouting the pre-stress anchor rod, horizontally penetrating through the middle rock column, and fixing and pre-tightening the two ends of the pre-stress anchor rod by using a second nut at the same time;
(4) Inverted arch excavation and two-lining construction: after the tunnel body is excavated, inverted arch support is timely carried out, the inverted arch support is closed to form a ring, concrete is timely sprayed to complete two-lining support, and each construction process and technical index of lining must meet design or specification requirements.
Compared with the prior art, the reinforcing structure and the construction method of the small-clear-distance tunnel have the following technical effects:
The reinforcement structure and the construction method of the small clear-distance tunnel reduce the vertical displacement and the transverse displacement of the middle rock column, improve the stability of the middle rock column in the small clear-distance tunnel, reduce the disturbance of blasting excavation on the excavated section of the tunnel, and ensure the safety of tunnel construction. The reinforcement structure and the construction method of the small clear distance tunnel effectively reduce the influence of the backward tunnel on the forward tunnel, reduce the pressure influence of the deformation of the middle rock column on the forward tunnel, prevent the expansion of the excavation section of the forward tunnel, and prevent the size of the tunnel section from being influenced by excavation blasting. And the primary support is carried out, the middle rock column is anchored in different forms by the guide pipe grouting anchor rod, the hollow grouting anchor rod and the prestressed anchor rod, the self-bearing capacity of surrounding rock can be fully utilized by the regional anchoring of the middle rock column, the stability of the mechanical parameters of the surrounding rock is improved, the stress change of the middle clamping rock after the stress state is changed, and the economic cost can be saved. The conduit grouting anchor rod and the hollow grouting anchor rod are initially sprayed after being driven, so that the influence of blasting tunneling of a backward tunnel on a forward tunnel is reduced for controlling early deformation of surrounding rock. The two-hole steel sheet is simple to manufacture and operate, the steel sheet is fully contacted with the middle rock column through the fastening of the first screw sleeve, the steel sheet has a better stress environment, and the annular surrounding rock primary lining of the poor geological section can be subjected to stress deformation sharing; the steel sheet has high operability, and the length can be adjusted according to the range of the poor geological section.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic structural view of a reinforcement structure of a small clear-distance tunnel of the present invention;
FIG. 2 is a schematic view of a portion of a reinforcement structure of a small clear-distance tunnel according to the present invention;
FIG. 3 is a schematic diagram of a portion of a reinforcement structure of a small clear-distance tunnel according to the present invention;
FIG. 4 is a schematic view of a steel sheet in the reinforcement structure of the small clear-distance tunnel of the present invention;
FIG. 5 is a schematic diagram II of a steel sheet in the reinforcement structure of the small clear-distance tunnel of the present invention;
FIG. 6 is a schematic view of a second nut in the reinforcement structure of the small clear-distance tunnel of the present invention;
FIG. 7 is a schematic diagram II of a second nut in the reinforcement structure of the small clear-distance tunnel of the present invention;
the concrete pile comprises a 1-hollow grouting anchor rod, a 2-prestressed anchor rod, a 3-conduit grouting anchor rod, a 4-concrete layer, 5-surrounding rock, 6-first nuts, 7-steel sheets, 71-through holes, 8-second nuts and 81-reinforcing ribs.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a reinforcing structure of a small-clearance tunnel and a construction method thereof, which are used for solving the problems in the prior art, reducing the vertical displacement and the transverse displacement of a middle rock column, improving the stability of the middle rock column in the small-clearance tunnel, reducing the disturbance of blasting excavation on the excavated section of the tunnel and guaranteeing the safety of tunnel construction.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
As shown in fig. 1-7, the reinforcement structure of the small clear-distance tunnel of the embodiment comprises a plurality of hollow grouting anchors 1, a plurality of prestressed anchors 2 and a plurality of conduit grouting anchors 3 which are arranged on a middle rock column of the small clear-distance tunnel, wherein the hollow grouting anchors 1 incline upwards, the prestressed anchors 2 are horizontal, and the conduit anchors incline downwards; the hollow grouting anchor rod 1 is arranged at the upper part of the middle rock column, the conduit grouting anchor rod 3 is arranged at the lower part of the middle rock column, the uniform ends of the hollow grouting anchor rod 1 and the conduit grouting anchor rod 3 are inserted into the middle rock column, the prestressed anchor rod 2 penetrates through the middle rock column, and the two ends of the prestressed anchor rod 2 are respectively positioned in two tunnels of the small clear-distance tunnel; the ends of the hollow grouting anchor rod 1 and the conduit grouting anchor rod 3, which are positioned in the tunnel, are respectively provided with a first screw cap 6, and the two ends of the prestressed anchor rod 2 are respectively provided with a second screw cap 8.
The hollow grouting anchor rods 1, the prestressed anchor rods 2 and the conduit grouting anchor rods 3 are respectively divided into a plurality of rows which are uniformly distributed, and two horizontally adjacent hollow grouting anchor rods 1 or conduit grouting anchor rods 3 are respectively sleeved with the same steel sheet 7; the middle of the steel sheet 7 is provided with a convex part, the two sides of the steel sheet 7 are provided with flat parts, the flat parts are provided with through holes 71 for penetrating through the hollow grouting anchor rod 1, the prestressed anchor rod 2 or the conduit grouting anchor rod 3, the installation directions of the two adjacent steel sheets 7 are opposite and buckled together, the steel sheets 7 are positioned between the first screw cap 6 and the side wall of the middle rock column, the steel sheets 7 are fully contacted with the middle rock column through the fastening of the first screw sleeve, the steel sheets 7 have better stress environment, and the primary lining of the annular surrounding rock 5 of the poor geological section can be subjected to the effect of sharing stress deformation; the steel sheet 7 is large in operability, and the length can be adjusted according to the range of the poor geological section. The thickness of the flat part is 5mm, the thickness of the protruding part is 10mm, and the total thickness of the two flat parts of the two steel sheets 7 after being overlapped together is just the same as the thickness of the protruding part. The hollow grouting anchor rod 1 and the conduit grouting conduit with the same horizontal height are connected into a whole, so that the overall performance parameters of the surrounding rock 5 are improved, the longitudinal displacement of the surrounding rock 5 is effectively reduced, and the occurrence of the circumferential collapse accident of a tunnel is reduced
The hollow grouting anchor rod 1 is arranged in the area from the top end of the middle rock column to 3/5 of the middle rock column, the conduit grouting anchor rod 3 is arranged in the area from the bottom end of the middle rock column to 2/5 of the middle rock column, and the prestressed anchor rod 2 is arranged in the area from 2/5 of the middle rock column to 3/5 of the middle rock column.
The second nut 8 one end is provided with a ring, is provided with four stiffening ribs 81 on the outer wall of second nut 8, and stiffening ribs 81 link firmly with the ring, and the setting of ring has increased the area of contact of second nut 8 with just lining, has improved the effect of prestressing force stock 2, has given a lateral pressure of well rock column, has increased the area of being stressed of middle part rock mass, reduces the horizontal displacement of well rock column country rock 5, and is with low costs and simple to operate.
The hollow grouting anchor rod 1 is fixedly connected with the surrounding rock 5 through slurry, the hollow grouting anchor rod 1 and the surrounding rock 5 form a combined reinforcing body, the self-stabilization capability of the surrounding rock 5 is improved, the occurrence time of a plastic region of a middle rock column is delayed, and the range of the plastic region is effectively reduced; the conduit anchor rod and surrounding rock mass form a compression belt, and the rock mass of the compression belt is in a three-way compression state, so that the conduit and the surrounding rock 5 form a combined reinforcement body, and the self-bearing capacity of the surrounding rock 5 is improved.
The embodiment also provides a construction method of the small clear distance tunnel, which comprises the following steps:
(1) Excavating a small clear distance tunnel in a weak crushing area, blasting surrounding rock 5 by adopting smooth blasting, controlling excavation footage according to 0.5m, performing supporting construction in each cycle, and grouting the lower part of a middle rock column in a preceding tunnel by adopting a guide pipe grouting anchor rod 3 after the preceding tunnel of the small clear distance tunnel is excavated, wherein the anchoring range is from the bottom end of the middle rock column to 2/5 height; the upper part of a middle rock column is reinforced by adopting a hollow grouting anchor rod 1, the anchoring range is from the position of the middle rock column at 3/5 height from the ground to the top end of the middle rock column, after the installation of the conduit grouting anchor rod 3 and the hollow grouting anchor rod 1 is finished, two horizontal two-hole steel sheets 7 are installed and fixed, the two steel sheets 7 are connected in a positive-negative way, each steel sheet 7 is connected with two adjacent conduit grouting anchor rods 3 or hollow grouting anchor rods 1 with the same horizontal line, after the splicing is finished, the two steel sheets are fixed by using a first screw cap 6, so that the conduit grouting anchor rods 3 or the hollow grouting anchor rods 1 with the same horizontal line are connected into a whole, and grouting is carried out;
(2) Excavating a backward tunnel, and grouting the lower part of a middle rock column in the backward tunnel by adopting a guide pipe grouting anchor rod 3 when the backward tunnel is excavated, wherein the anchoring range is from the bottom end of the middle rock column to the position of 2/5 of the height; the upper part of a middle rock column in a backward tunnel is reinforced by adopting a hollow grouting anchor rod 1, the anchoring range is from the position of the middle rock column at 3/5 height from the ground to the top end of the middle rock column, a horizontal two-hole steel sheet 7 is installed after the installation of the conduit grouting anchor rod 3 and the hollow grouting anchor rod 1 is completed, the two-hole steel sheets 7 are connected in a positive-negative way, each steel sheet 7 is connected with two adjacent conduit grouting anchor rods 3 or hollow grouting anchor rods 1 with the same horizontal line, after the splicing is completed, the two adjacent conduit grouting anchor rods 3 or hollow grouting anchor rods 1 with the same horizontal line are fixed by using a first screw cap 6, so that the conduit grouting anchor rods 3 or the hollow grouting anchor rods 1 with the same horizontal line are connected into a whole, and grouting and concrete spraying are performed;
(3) A prestressed anchor rod 2 is arranged in the middle of the middle rock column, grouting is carried out on the prestressed anchor rod 2, the prestressed anchor rod horizontally penetrates through the middle rock column, and the two ends of the prestressed anchor rod 2 are simultaneously fixed and pre-tightened by a second nut 8;
(4) Inverted arch excavation and two-lining construction: after the tunnel body is excavated, inverted arch support is timely carried out, the inverted arch support is closed to form a ring, concrete is timely sprayed to complete two-lining support, and each construction process and technical index of lining must meet design or specification requirements.
Through practical inspection, the reinforcement structure and the construction method of the small-clear-distance tunnel of the embodiment are reduced by about 80% compared with the conventional reinforcement vertical displacement, and the horizontal displacement is reduced by about 20%; the vertical stress is reduced by 5 to 10 percent, and the reinforcement effect is very obvious; the tunnel collapse or tunnel ring lining fragmentation condition of the surrounding rock 5 is obviously reduced.
In the description of the present invention, it should be noted that the positional or positional relationship indicated by the terms such as "top", "bottom", "upper", "lower", "horizontal", etc. are based on the positional or positional relationship shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or element in question must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The principles and embodiments of the present invention have been described in detail with reference to specific examples, which are provided to facilitate understanding of the method and core ideas of the present invention; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (5)
1. The utility model provides a reinforced structure in small clear distance tunnel which characterized in that: the grouting device comprises a plurality of hollow grouting anchors, a plurality of prestressed anchors and a plurality of conduit grouting anchors, wherein the hollow grouting anchors are arranged on a middle rock column of a small-clearance tunnel, the hollow grouting anchors are arranged on the upper part of the middle rock column, the conduit grouting anchors are arranged on the lower part of the middle rock column, the hollow grouting anchors and the conduit grouting anchors are uniformly inserted into the middle rock column, the prestressed anchors penetrate through the middle rock column, and two ends of the prestressed anchors are respectively positioned in two tunnels of the small-clearance tunnel; the two adjacent hollow grouting anchor rods or the conduit grouting anchor rods are sleeved with the same steel sheet, the end parts of the hollow grouting anchor rods and the conduit grouting anchor rods, which are positioned in the tunnel, are provided with first nuts, the steel sheet is positioned between the first nuts and the side wall of the middle rock column, and the two ends of the prestressed anchor rods are respectively provided with second nuts; the hollow grouting anchor rods, the prestressed anchor rods and the conduit grouting anchor rods are respectively divided into a plurality of rows which are uniformly distributed, and two horizontally adjacent hollow grouting anchor rods or conduit grouting anchor rods are respectively sleeved with the same steel sheet; the middle of the steel sheet is provided with a protruding part, the two sides of the steel sheet are provided with flat parts, the flat parts are provided with a through hole for penetrating through the hollow grouting anchor rod, the prestressed anchor rod or the conduit grouting anchor rod, and the installation directions of two adjacent steel sheets are opposite and buckled together; the hollow grouting anchor rod is fixedly connected with surrounding rock through mud, the hollow grouting anchor rod and the surrounding rock form a combined reinforcing body, and the conduit grouting anchor rod and surrounding rock form a compression belt; the hollow grouting anchor rod is inclined upwards, the prestressed anchor rod is horizontal, and the conduit grouting anchor rod is inclined downwards.
2. The small clear-distance tunnel reinforcement structure of claim 1, wherein: the thickness of the flat part is 5mm, and the thickness of the protruding part is 10mm.
3. The small clear-distance tunnel reinforcement structure of claim 1, wherein: the hollow grouting anchor rod is arranged in the area from the top end of the middle rock column to 3/5 of the height of the middle rock column, the conduit grouting anchor rod is arranged in the area from the bottom end of the middle rock column to 2/5 of the height of the middle rock column, and the prestressed anchor rod is arranged in the area from 2/5 of the height of the middle rock column to 3/5 of the height of the middle rock column.
4. The small clear-distance tunnel reinforcement structure of claim 1, wherein: one end of the second nut is provided with a circular ring, four reinforcing ribs are arranged on the outer wall of the second nut, and the reinforcing ribs are fixedly connected with the circular ring.
5. The construction method of the small clear distance tunnel is characterized by comprising the following steps of:
(1) Excavating a small clear distance tunnel in a weak crushing area, blasting surrounding rock by adopting smooth blasting, controlling excavation footage according to 0.5m, performing supporting construction in each cycle, and grouting the lower part of a middle rock column in a preceding tunnel by adopting a guide pipe grouting anchor rod after the preceding tunnel of the small clear distance tunnel is excavated, wherein the anchoring range is from the bottom end of the middle rock column to 2/5 height; the upper part of the middle rock column is reinforced by adopting a hollow grouting anchor rod, the anchoring range is from the position of the middle rock column at 3/5 height from the ground to the top end of the middle rock column, the conduit grouting anchor rod and the hollow grouting anchor rod are fixed by installing horizontal two-hole steel sheets after being installed, the two-hole steel sheets are positively and negatively connected, each steel sheet is connected with the conduit grouting anchor rods or the hollow grouting anchor rods of two adjacent same horizontal lines, the conduit grouting anchor rods or the hollow grouting anchor rods of the same horizontal lines are fixed by using first nuts after being spliced, so that the conduit grouting anchor rods or the hollow grouting anchor rods of the same horizontal lines are connected into a whole, and grouting is performed;
(2) Excavating a backward tunnel, and grouting the lower part of a middle rock column in the backward tunnel by adopting a conduit grouting anchor rod when the backward tunnel is excavated, wherein the anchoring range is from the bottom end of the middle rock column to the position of 2/5 of the height; the upper part of the middle rock column in the backward tunnel is reinforced by adopting a hollow grouting anchor rod, the anchoring range is from the position of 3/5 of the middle rock column to the ground to the top end of the middle rock column, the conduit grouting anchor rod and the hollow grouting anchor rod are fixed by installing horizontal two-hole steel sheets after being installed, the two-hole steel sheets are positively and negatively connected, each steel sheet is connected with the conduit grouting anchor rod or the hollow grouting anchor rod of two adjacent same horizontal lines, and the conduit grouting anchor rod or the hollow grouting anchor rod of the same horizontal line are fixed by using a first screw cap after being spliced, so that the conduit grouting anchor rod or the hollow grouting anchor rod of the same horizontal line are connected into a whole, and grouting and concrete spraying are carried out;
(3) Installing a pre-stress anchor rod in the middle of the middle rock column, grouting the pre-stress anchor rod, horizontally penetrating through the middle rock column, and fixing and pre-tightening the two ends of the pre-stress anchor rod by using a second nut at the same time;
(4) Inverted arch excavation and two-lining construction: after the tunnel body is excavated, inverted arch support is timely carried out, the inverted arch support is closed to form a ring, concrete is timely sprayed to complete two-lining support, and each construction process and technical index of lining must meet design or specification requirements.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910649883.1A CN110566253B (en) | 2019-07-18 | 2019-07-18 | Reinforcing structure of small-clear-distance tunnel and construction method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910649883.1A CN110566253B (en) | 2019-07-18 | 2019-07-18 | Reinforcing structure of small-clear-distance tunnel and construction method |
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| CN110566253A CN110566253A (en) | 2019-12-13 |
| CN110566253B true CN110566253B (en) | 2024-07-23 |
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| CN113047865A (en) * | 2021-03-31 | 2021-06-29 | 中建二局第三建筑工程有限公司 | Clamping and reinforcing bent frame for middle rock pillar of large-section small-clear-distance tunnel and construction method of clamping and reinforcing bent frame |
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