CN114198105A - Construction method for excavating underground tunnel body of broken water-rich phyllite - Google Patents
Construction method for excavating underground tunnel body of broken water-rich phyllite Download PDFInfo
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- CN114198105A CN114198105A CN202111529980.0A CN202111529980A CN114198105A CN 114198105 A CN114198105 A CN 114198105A CN 202111529980 A CN202111529980 A CN 202111529980A CN 114198105 A CN114198105 A CN 114198105A
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/003—Linings or provisions thereon, specially adapted for traffic tunnels, e.g. with built-in cleaning devices
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—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 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
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/14—Lining predominantly with metal
- E21D11/15—Plate linings; Laggings, i.e. linings designed for holding back formation material or for transmitting the load to main supporting members
- E21D11/152—Laggings made of grids or nettings
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- E—FIXED CONSTRUCTIONS
- E21—EARTH 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
Abstract
A construction method for excavating a broken water-rich phyllite lower hole body relates to a construction method for excavating a phyllite lower hole body, and can complete the excavation support looping operation of the phyllite lower hole body by expanding section construction, closing tunnel face surrounding rock, advancing hole probing operation, advance support construction, annular excavation of an upper step, closing surrounding rock by primary shotcrete, mounting a primary support steel frame and a reinforcing mesh, re-shotcreting concrete, constructing system anchor pipes, and excavating and supporting the middle step, the lower step and an inverted arch; in the construction process, the one-time supporting quantity is small, the construction process is easy, the operation is convenient, the middle pipe shed and the small pipe can be complemented on the external inserting angle, and the advanced supporting effect is outstanding; and a seamless steel pipe is adopted as a system anchor pipe along the circumferential direction of the tunnel, grouting reinforcement is carried out on surrounding rocks within a certain range of the tunnel body, consolidation can be carried out on loose rock masses within a certain range around the tunnel body under the action of grout, the deformation resistance of the surrounding rocks is improved, and annular reinforcement shell protection is formed in the tunnel.
Description
Technical Field
The invention relates to a construction method for excavating a phyllite lower hole body, in particular to a construction method for excavating a broken water-rich phyllite lower hole body.
Background
As is known, an expressway is an important component of a national transportation network, which greatly shortens the passage time between regions and improves the passage quality, and as a road network for national or regional connection, after the road network is designed and optimized, the expressway is required to cross mountains and rivers, and when traversing mountains, the encountered geological environment is complex and changeable, and particularly in a region where a regional geological structure develops.
Phyllite is a shallow metamorphic rock with a structure of thousand sheets, and is mostly formed by regional geological changes of mudstone, siltstone or partial volcanic rock and volcaniclastic rock. The water-retaining wall is easy to soften when meeting water, the whole body tends to be in a stable saturated state before being disturbed by excavation in a water-rich environment, and once an empty surface is formed or disturbed, the deformation or instability is easy to occur in the construction process; therefore, the construction method for excavating the broken water-rich phyllite lower hole body has simple and safe construction process, and becomes the basic appeal of technical personnel in the field.
Disclosure of Invention
In order to overcome the defects in the background art, the invention discloses a construction method for excavating a hole body under crushed water-rich phyllite.
In order to realize the purpose, the invention adopts the following technical scheme:
a construction method for excavating a tunnel body under crushed water-rich phyllite specifically comprises the following construction steps:
(1) and enlarging the cross section
Constructing and expanding a section at the construction position of the middle pipe shed two to three frames in advance, wherein the expanded section is formed by outwards expanding and excavating the thickness of a primary support on the upper side wall and the arch part of the original section foundation, and the support operation is completed according to the primary support mode of the original section;
(2) tunnel face wall rock sealing
When the last cycle of primary support construction of the expanded section is carried out, the front tunnel face is sealed by adopting closed sprayed concrete, and the thickness is 5-8 cm;
(3) advanced borehole drilling operation
Leveling an operation platform of the drilling machine, respectively arranging an advance probing hole on the upper step, the left side and the right side, recording the drilling speed, coring condition, water outlet point position, flow, water pressure, water temperature and water outlet state in a drilling process in detail, and guiding subsequent construction operation through the advance probing holes;
(4) advanced support construction
Marking the hole positions of the middle pipe shed at the arch part, and sequentially completing drilling operation from bottom to top, wherein the middle pipe shed is timely installed by combining the drilling record and the hole forming condition after the drilling machine drills a hole, so that hole collapse is prevented in the subsequent drilling process of the drilling machine, and the drilling of the middle pipe shed is alternately performed from bottom to top along the left side and the right side of the center line of the tunnel;
after the whole middle pipe shed is installed, arranging advanced small guide pipes among the middle pipe sheds in a staggered mode, driving the advanced small guide pipes into the middle pipe sheds by using air drills, performing advanced support reinforcement through the advanced small guide pipes, and grouting and pre-reinforcing the middle pipe sheds and the advanced small guide pipes in time after the construction is finished;
(5) annular excavation of upper step
The excavation height of the upper step is 1/3 of the whole section height, and core soil with the volume not less than 50% of the section area of the upper step is reserved on the upper step; the excavation mode mainly adopts mechanical excavation, loose blasting auxiliary excavation is adopted for hard rock blocks or boulders mixed locally, one arch truss is excavated in each cycle, the cycle footage is not too long or short, the instability of surrounding rocks caused by long-distance footage is avoided, the distance between core soil and an excavation contour line is 1.1-1.3m, and the operation space of personnel is ensured;
(6) first-spraying concrete closed surrounding rock
The first step is carried out, after excavation is finished, exposed surrounding rock primary spraying concrete is sealed, and a local concave cavity is backfilled during primary spraying;
(7) mounting of primary support steel frame and reinforcing mesh
The method comprises the following steps of (1) connecting, measuring and lofting, mounting a primary support steel frame, respectively arranging two foot-contracting anchor pipes at left and right arch foot positions of each step, wherein the foot-contracting anchor pipes are seamless steel pipes, phi 25mm L-shaped reinforcing steel bars are welded at the ends of the foot-contracting anchor pipes, the length of the long sides of the L-shaped reinforcing steel bars is not less than 25cm, the length of the short sides of the L-shaped reinforcing steel bars is 10cm, the long sides of the L-shaped reinforcing steel bars are welded and connected with the foot-contracting anchor pipes, and after the primary support steel frame is positioned, the left and right foot-contracting anchor pipes are welded and fixed with the primary support steel frame through the short sides of the L-shaped reinforcing steel bars;
each primary support steel frame is longitudinally connected and fixed by connecting ribs, and each two primary support steel frames are connected and fixed by connecting joints through bolts;
the reinforcing mesh and the primary support steel frame can be synchronously installed and are all installed after the primary sprayed concrete closes the surrounding rock, the reinforcing mesh is laid along with the surface of the sprayed rock, the lapping length of reinforcing steel bars of the reinforcing mesh is not less than 30 times of the diameter of the reinforcing steel bars, and the reinforcing mesh is fixed by the primary support steel frame to prevent the reinforcing mesh from shaking when the concrete is sprayed again;
(8) composite spray concrete
The step is connected, concrete is sprayed again until the primary support steel frame is completely covered, a protective layer is formed on the inner side of the primary support steel frame, meanwhile, reinforcing mesh is hung on the middle pipe shed exposed on the inner side of the expanded section, concrete is sprayed again, and the middle pipe shed is wrapped by sprayed concrete in thickness;
(9) construction of system anchor pipe
Sequentially punching and installing the system anchor pipe from bottom to top along the mounting position of the system anchor pipe which is marked in the circumferential direction, wherein the system anchor pipe is made of a seamless steel pipe, small holes are uniformly formed in the pipe body of the system anchor pipe, and grouting is performed in time after the system anchor pipe is installed so as to consolidate the surrounding rock mass;
(10) and the step of connecting is carried out, and excavation supporting ring formation of the phyllite lower hole body can be completed by centering the step, the lower step and the inverted arch excavation supporting.
According to the construction method for excavating the hole body under the crushed water-rich phyllite, in the step (1), the length of a corresponding primary support steel frame is constructed according to the length of an enlarged section, the construction length of the enlarged section is controlled according to the type of a drilling machine and an operation space, and the tail of a pipe shed does not encroach on the clearance of the section after the construction of the pipe shed; the construction steps of the twice primary support for expanding the section sequentially comprise: the construction method comprises the steps of installing the support steel frame 2 at the initial stage of the expanded section, spraying and mixing the reinforcing mesh and the expanded section at one time, installing and grouting anchor pipes of the system and spraying concrete again on the expanded section.
According to the construction method for excavating the hole body under the crushed water-rich phyllite, the expansion section primary spraying and mixing means that concrete is sprayed on the excavated exposed surface to seal, the concrete is continuously sprayed and mixed until the primary support steel frame is wrapped after the primary support steel frame, the reinforcing mesh and the like are installed, and the expansion section secondary spraying concrete means that the expanded section exposed middle pipe shed is wrapped and sealed after the construction of the middle pipe shed is finished, so that the whole section is longitudinally and smoothly connected.
In the construction method for excavating the underground tunnel body of the crushed water-rich phyllite, in the step (3), the depth of the advanced exploring hole is 50m, the aperture is phi 76mm, and the drilling angle is reasonably arranged by combining geophysical prospecting.
In the construction method for excavating the hole body under the crushed water-rich phyllite, in the step (4), the tunnel face-side middle tube shed is made of seamless steel tubes with the diameter of 76mm and the diameter of 5mm, the length of the steel tubes is 9m, the circumferential distance is 0.4m, the external insertion angle is not more than 15 degrees, and the external insertion angle is based on ensuring that the tail part of the middle tube shed expands the section clearance and the section steel of the front normal section of the middle tube shed is smoothly installed.
In the construction method for excavating the hole body under the crushed water-rich phyllite, in the step (4), the grouting slurry can adopt cement-water glass double-liquid slurry or cement single-liquid slurry.
In the construction method for excavating the hole body under the crushed water-rich phyllite, in the step (6), the thickness of the primary sprayed concrete is 4 cm.
In the construction method for excavating the hole body under the crushed water-rich phyllite, in the step (7), an included angle between two foot-contracting anchor pipes is 20 degrees, and an included angle between the foot-contracting anchor pipe positioned at the upper part and the lower part of a horizontal plane is 20 degrees;
in the construction method for excavating the lower hole body of the crushed water-rich phyllite, in the step (10), the footage of the middle step 11 and the lower step does not exceed two arch frames each cycle of excavation, the front and the back of the left side and the right side of the same step are staggered by 3-5 m, the front and the back of the upper step and the back of the lower step are staggered by 3-5 m, and two sides of the same arch frame cannot be suspended simultaneously.
According to the construction method for excavating the hole body under the broken water-rich phyllite, in the step (10), the inverted arch operation step is that construction is carried out immediately along with the next step, the footage is not more than 3m every cycle, the excavation depth is marked on the inverted arch firstly during operation, mechanical layered excavation is adopted, the excavation depth is not too deep every time, the inverted arch is prevented from being over excavated, inverted arch ring formation is completed in time after excavation, seepage water in the hole body range needs to be collected and pumped out before excavation, and accumulated water cannot soak the inverted arch or arch feet.
Due to the adoption of the technical scheme, the invention has the following beneficial effects:
1. according to the construction method for excavating the hole body under the crushed water-rich phyllite, the advanced support adopts the in-hole middle pipe shed and the advanced small guide pipe support, the primary support adopts the support mode of steel frames, steel bar meshes, sprayed concrete and system anchor pipes, and the advanced support mode of the middle pipe shed and the advanced small guide pipe, so that the advanced support effect of the crushed body is enhanced on one hand; on the other hand, the long and short sides are combined for reinforcement, meanwhile, an annular reserved core soil method is adopted for upper step excavation, construction is carried out on the upper step, the middle step, the lower step and the three steps, the exposure of the open face of surrounding rock on the tunnel face is further reduced, the self-stability capability of the surrounding rock is maintained, excavation is carried out by a top-down micro-step method until inverted arch closed-loop construction is completed, and the method is suitable for soft rock construction of a single-line double-lane tunnel of a highway.
2. According to the construction method for excavating the hole body under the crushed water-rich phyllite, the advance support is supported by the medium pipe shed and the small guide pipes, in the construction process, the middle pipe shed and the small guide pipes are alternately carried out with the excavation operation, the supporting amount at one time is small, the construction process is easy, the operation is convenient, the medium pipe shed and the small guide pipes can be complemented on the external inserting angle, and the advance support effect is remarkable; and a seamless steel pipe is adopted as a system anchor pipe along the circumferential direction of the tunnel, grouting reinforcement is carried out on surrounding rocks within a certain range of the tunnel body, consolidation can be carried out on loose rock masses within a certain range around the tunnel body under the action of grout, the deformation resistance of the surrounding rocks is improved, and annular reinforcement shell protection is formed in the tunnel.
Drawings
Fig. 1 is a longitudinal sectional view of the present invention taken along a tunnel.
Figure 2 is a schematic illustration of the support of the widened section cross-section of the present invention.
FIG. 3 is an enlarged schematic view at A in FIG. 1
Fig. 4 is a schematic structural view of the foot-retracting anchor tube of the present invention.
Fig. 5 is an enlarged schematic view at B in fig. 4.
Fig. 6 is a schematic view of the installation of the foot-retracting anchor tube of the present invention.
FIG. 7 is a view showing the connection structure of the anchor pipe with the foot and the L-shaped reinforcing steel bar according to the present invention.
In the figure: 1. an inverted arch; 2. primary steel frame support; 3. a small advanced catheter; 4. expanding the section for one time of spraying and mixing; 5. a middle pipe shed; 6. trenchless rock mass; 7. an upper step; 8. closed shotcrete; 9. expanding the section and spraying concrete again; 10. core soil; 11. a middle step; 12. an operating platform; 13. descending a step; 14. backfilling the driving channel with waste slag; 15. a system anchor pipe; 16. a seam-filling steel plate; 17. a bolt; 18. an arch springing; 19. a foot-contracting anchor pipe; 20. connecting a joint; 21. l-shaped steel bars.
Detailed Description
The present invention will be explained in detail by the following examples, which are disclosed for the purpose of protecting all technical improvements within the scope of the present invention.
The construction method for excavating the underground tunnel body of the crushed water-rich phyllite comprises the following construction steps:
(1) and enlarging the cross section
Constructing and expanding a section at the construction position of the middle pipe shed 5 two to three frames in advance, wherein the expanded section is formed by outwards expanding and excavating the thickness of a primary support on the upper side wall and the arch part of the original section, and finishing the support operation according to the primary support mode of the original section; the length of the corresponding primary support steel frame 2 is constructed according to the length of the enlarged section, the construction length of the enlarged section is controlled according to the type of a drilling machine and the operation space, and the tail of the pipe shed does not occupy the clearance of the section after the construction of the middle pipe shed; the construction steps of the twice primary support for expanding the section sequentially comprise: installing an expanded section primary support steel frame 2, carrying out primary spraying and mixing on a reinforcing mesh and an expanded section 4, installing and grouting a system anchor pipe 15, and carrying out construction of expanded section re-spraying concrete 9;
the step 4 of expanding the section by one-time spraying and mixing means that the excavated exposed surface is sprayed with concrete and sealed, the concrete is continuously sprayed and mixed until the primary support steel frame 2 is wrapped after the primary support steel frame 2, the reinforcing mesh and the like are installed, and the step 9 of expanding the section by re-spraying concrete means that the middle pipe shed 5 exposed on the expanded section is wrapped and sealed after the construction of the middle pipe shed 5 is finished, so that the whole section is longitudinally and smoothly connected;
(2) tunnel face wall rock sealing
When the last cycle of primary support construction of the expanded section is carried out, the front tunnel face is sealed by adopting closed sprayed concrete 8, and the thickness is 5-8 cm;
(3) advanced borehole drilling operation
Leveling an operation platform 12 of the drilling machine, respectively arranging an advance probing hole on the upper step 7, the left side and the right side, recording the drilling speed, coring condition, water outlet position, flow, water pressure, water temperature and water outlet state in detail in the drilling process, and guiding subsequent construction operation through the advance probing holes; the depth of the advanced probing hole is 50m, the aperture is phi 76mm, and the drilling angle is reasonably arranged in combination with geophysical prospecting; on one hand, a prediction basis is provided for the geological condition in front of the tunnel face, and on the other hand, the front rich water can be discharged through a drill hole to reduce pressure; a waste slag backfilling running channel 14 is arranged at the lower part of the operating platform 12;
(4) advanced support construction
Marking the drilling hole positions of the middle pipe shed 5 at the arch part, sequentially completing the drilling operation from bottom to top, and timely installing the middle pipe shed 5 by combining the drilling record and the hole forming condition after the drilling machine drills a hole, so as to prevent hole collapse in the subsequent drilling process of the drilling machine, wherein the drilling of the middle pipe shed 5 is alternately performed from bottom to top along the left side and the right side of the center line of the tunnel;
after the whole middle pipe shed 5 is installed, arranging the small advanced guide pipes 3 among the middle pipe sheds 5 in a staggered mode, driving the small advanced guide pipes 3 by using a pneumatic drill, performing advanced support reinforcement through the small advanced guide pipes 3, and grouting for pre-reinforcement in time after the construction of the middle pipe shed 5 and the small advanced guide pipes 3 is finished, wherein grouting slurry can be cement-water glass double-liquid slurry or cement single-liquid slurry;
the middle pipe shed 5 on the tunnel face is made of seamless steel pipes with the diameter of 76mm plus 5mm, the length of the steel pipes is 9m, the circumferential distance is 0.4m, the external insertion angle is not more than 15 degrees, and the external insertion angle is based on ensuring that the tail part of the middle pipe shed 5 expands the section clearance and the primary support section steel 2 of the normal section in front of the middle pipe shed 5 is smoothly installed;
(5) annular excavation of upper step
The excavation height of the upper step 7 is 1/3 of the whole section height, and core soil 10 with the volume not less than 50% of the section area of the upper step is reserved on the upper step 7; the excavation mode mainly adopts mechanical excavation, loose blasting auxiliary excavation is adopted for hard rock blocks or boulders mixed locally, one arch truss is excavated in each cycle, the cycle footage is not too long or short, the instability of surrounding rocks caused by long-distance footage is avoided, the distance between core soil and an excavation contour line is 1.1-1.3m, and the operation space of personnel is ensured;
(6) first-spraying concrete closed surrounding rock
The method comprises the following steps of firstly, sealing exposed surrounding rock primary-spraying concrete after excavation is finished, and backfilling a local concave cavity during primary spraying, so that on one hand, a relatively safe operation space is provided for subsequent process construction to prevent local block falling, on the other hand, a flat paved surface is provided for reinforcing mesh laying operation, and the thickness of the primary-spraying concrete is 4 cm;
(7) mounting of primary support steel frame 2 and reinforcing mesh
The method comprises the following steps of (1) connecting a step, measuring and lofting, installing a primary support steel frame 2, arranging two foot-contracting anchor pipes 19 at the left and right arch feet 18 of each step, wherein the foot-contracting anchor pipes 19 are seamless steel pipes, phi 25mm L-shaped reinforcing steel bars 21 are welded at the ends of the foot-contracting anchor pipes 19, the length of the long sides of the L-shaped reinforcing steel bars 21 is not less than 25cm, the length of the short sides of the L-shaped reinforcing steel bars 21 is 10cm, the long sides are welded with the foot-contracting anchor pipes 19, and after the primary support steel frame 2 is positioned, the left and right foot-contracting anchor pipes 19 are welded and fixed with the primary support steel frame 2 through the short sides of the L-shaped reinforcing steel bars 21; the included angle between the two foot-contracting anchor pipes 19 is 20 degrees, and the included angle between the foot-contracting anchor pipe 19 positioned at the upper part and the lower part of the horizontal plane is 20 degrees;
each primary support steel frame 2 is longitudinally connected and fixed by connecting ribs, each two primary support steel frames 2 are connected and fixed by connecting joints 20 through bolts 17, and after the primary support steel frames 2 are installed, gaps exist at the connecting joints 20 and are filled by gap filling steel plates 16 and are welded and fixed, so that primary support instability caused by the fact that the gaps exist in the connecting joints 19 and cannot resist deformation after the primary support steel frames 2 are stressed is prevented;
the reinforcing mesh and the primary support steel frame 2 can be synchronously installed and are all installed after the primary sprayed concrete closes the surrounding rock, the reinforcing mesh is laid along with the surface of the sprayed rock, the lapping length of reinforcing steel bars of the reinforcing mesh is not less than 30 times of the diameter of the reinforcing steel bars, and the reinforcing mesh is fixed through the primary support steel frame 2 to prevent the reinforcing mesh from shaking when the concrete is sprayed again;
(8) composite spray concrete
The step is connected, concrete is sprayed again until the primary support steel frame 2 is completely covered, a protective layer is formed on the inner side, meanwhile, reinforcing mesh is hung on the middle pipe shed exposed on the inner side of the enlarged section, concrete is sprayed again, and the middle pipe shed 5 is wrapped by sprayed concrete in thickness;
(9) construction of system anchor pipe 15
Sequentially punching and installing the system anchor pipe 15 from bottom to top along the installation position of the system anchor pipe 15 in the circumferential direction, wherein the system anchor pipe 15 is made of a seamless steel pipe, small holes are uniformly distributed in the pipe body of the system anchor pipe 15, and grouting is performed in time after the installation to consolidate and reinforce the surrounding rock mass;
(10) the step of connecting is carried out, namely excavation supporting of the middle step 11, the lower step 13 and the inverted arch 1 is carried out, and excavation supporting ring formation of the phyllite lower hole body can be completed; the footage of each cycle of excavation of the middle step 11 and the lower step 13 does not exceed two trusses of arch frames, the front and back of excavation of the left side and the right side of the same step are staggered by 3m to 5m, the front and back of excavation of the upper step and the lower step are staggered by 3m to 5m, and two sides of the same truss of arch frames cannot be suspended simultaneously; mechanical excavation is adopted when the lower step 13 is excavated, and the installed arch center and the foot-contracting anchor pipe 19 are not required to be touched during the mechanical excavation process, so that the arch center of the upper step is prevented from being disturbed; the inverted arch 1 operation steps are, follow the lower step 13 construction closely, every circulation footage is not more than 3m, mark out the excavation depth on the inverted arch 1 first during operation, adopt mechanical layering excavation, the excavation depth should not be too deep at every turn, avoid inverted arch 1 to overbreak, in time accomplish inverted arch 1 cyclization after the excavation, need collect the drainage to the infiltration in the body scope of the hole before the excavation, ponding must not soak inverted arch 1 or hunch.
The present invention is not described in detail in the prior art.
The embodiments selected for the purpose of disclosing the invention, are presently considered to be suitable, it being understood, however, that the invention is intended to cover all variations and modifications of the embodiments which fall within the spirit and scope of the invention.
Claims (10)
1. A construction method for excavating a tunnel body under crushed water-rich phyllite is characterized by comprising the following steps: the construction method specifically comprises the following construction steps:
(1) and enlarging the cross section
Constructing and expanding a section at the construction position of the middle pipe shed two to three frames in advance, wherein the expanded section is formed by outwards expanding and excavating the thickness of a primary support on the upper side wall and the arch part of the original section foundation, and the support operation is completed according to the primary support mode of the original section;
(2) tunnel face wall rock sealing
When the last cycle of primary support construction of the expanded section is carried out, the front tunnel face is sealed by adopting closed sprayed concrete, and the thickness is 5-8 cm;
(3) advanced borehole drilling operation
Leveling an operation platform of the drilling machine, respectively arranging an advance probing hole on the upper step, the left side and the right side, recording the drilling speed, coring condition, water outlet point position, flow, water pressure, water temperature and water outlet state in a drilling process in detail, and guiding subsequent construction operation through the advance probing holes;
(4) advanced support construction
Marking the hole positions of the middle pipe shed at the arch part, and sequentially completing drilling operation from bottom to top, wherein the middle pipe shed is timely installed by combining the drilling record and the hole forming condition after the drilling machine drills a hole, so that hole collapse is prevented in the subsequent drilling process of the drilling machine, and the drilling of the middle pipe shed is alternately performed from bottom to top along the left side and the right side of the center line of the tunnel;
after the whole middle pipe shed is installed, arranging advanced small guide pipes among the middle pipe sheds in a staggered mode, driving the advanced small guide pipes into the middle pipe sheds by using air drills, performing advanced support reinforcement through the advanced small guide pipes, and grouting and pre-reinforcing the middle pipe sheds and the advanced small guide pipes in time after the construction is finished;
(5) annular excavation of upper step
The excavation height of the upper step is 1/3 of the whole section height, and core soil with the volume not less than 50% of the section area of the upper step is reserved on the upper step; the excavation mode mainly adopts mechanical excavation, loose blasting auxiliary excavation is adopted for hard rock blocks or boulders mixed locally, one arch truss is excavated in each cycle, the cycle footage is not too long or short, the instability of surrounding rocks caused by long-distance footage is avoided, the distance between core soil and an excavation contour line is 1.1-1.3m, and the operation space of personnel is ensured;
(6) first-spraying concrete closed surrounding rock
The first step is carried out, after excavation is finished, exposed surrounding rock primary spraying concrete is sealed, and a local concave cavity is backfilled during primary spraying;
(7) mounting of primary support steel frame and reinforcing mesh
The method comprises the following steps of (1) connecting, measuring and lofting, mounting a primary support steel frame, respectively arranging two foot-contracting anchor pipes at left and right arch foot positions of each step, wherein the foot-contracting anchor pipes are seamless steel pipes, phi 25mm L-shaped reinforcing steel bars are welded at the ends of the foot-contracting anchor pipes, the length of the long sides of the L-shaped reinforcing steel bars is not less than 25cm, the length of the short sides of the L-shaped reinforcing steel bars is 10cm, the long sides of the L-shaped reinforcing steel bars are welded and connected with the foot-contracting anchor pipes, and after the primary support steel frame is positioned, the left and right foot-contracting anchor pipes are welded and fixed with the primary support steel frame through the short sides of the L-shaped reinforcing steel bars;
each primary support steel frame is longitudinally connected and fixed by connecting ribs, and each two primary support steel frames are connected and fixed by connecting joints through bolts;
the reinforcing mesh and the primary support steel frame can be synchronously installed and are all installed after the primary sprayed concrete closes the surrounding rock, the reinforcing mesh is laid along with the surface of the sprayed rock, the lapping length of reinforcing steel bars of the reinforcing mesh is not less than 30 times of the diameter of the reinforcing steel bars, and the reinforcing mesh is fixed through the primary support steel frame;
(8) composite spray concrete
The step is connected, concrete is sprayed again until the primary support steel frame is completely covered, a protective layer is formed on the inner side of the primary support steel frame, meanwhile, reinforcing mesh is hung on the middle pipe shed exposed on the inner side of the expanded section, concrete is sprayed again, and the middle pipe shed is wrapped by sprayed concrete in thickness;
(9) construction of system anchor pipe
Sequentially punching and installing the system anchor pipe from bottom to top along the mounting position of the system anchor pipe which is marked in the circumferential direction, wherein the system anchor pipe is made of a seamless steel pipe, small holes are uniformly formed in the pipe body of the system anchor pipe, and grouting is performed in time after the system anchor pipe is installed so as to consolidate the surrounding rock mass;
(10) and the step of connecting is carried out, and excavation supporting ring formation of the phyllite lower hole body can be completed by centering the step, the lower step and the inverted arch excavation supporting.
2. The construction method for excavating the underground cave body of the crushed water-rich phyllite as claimed in claim 1, wherein: in the step (1), the length of the corresponding primary support steel frame is constructed according to the length of the enlarged section, the construction length of the enlarged section is controlled according to the type of a drilling machine and an operation space, and the tail of a pipe shed does not occupy the clearance of the section after the construction of the pipe shed; the construction steps of the twice primary support for expanding the section sequentially comprise: the construction method comprises the steps of installing the support steel frame 2 at the initial stage of the expanded section, spraying and mixing the reinforcing mesh and the expanded section at one time, installing and grouting anchor pipes of the system and spraying concrete again on the expanded section.
3. The construction method for excavating the underground cave body of the crushed water-rich phyllite as claimed in claim 1, wherein: the expansion section primary spraying and mixing means that concrete spraying and sealing are carried out on the excavated exposed surface, the concrete spraying and mixing are continued until the primary support steel frame is wrapped after the primary support steel frame, the reinforcing mesh and the like are installed, and the expansion section re-spraying concrete means that the expanded section exposed pipe shed is wrapped and sealed after the construction of the pipe shed is finished, so that the whole section is longitudinally and smoothly connected.
4. The construction method for excavating the underground cave body of the crushed water-rich phyllite as claimed in claim 1, wherein: in the step (3), the depth of the advance probing hole is 50m, the aperture is phi 76mm, and the drilling angle is reasonably arranged in combination with geophysical prospecting.
5. The construction method for excavating the underground cave body of the crushed water-rich phyllite as claimed in claim 1, wherein: in the step (4), the tunnel face-in-tunnel shed is made of seamless steel pipes with the diameter of 76mm plus 5mm, the length of the steel pipes is 9m, the circumferential distance is 0.4m, the external insertion angle is not more than 15 degrees, and the external insertion angle is based on ensuring that the tail of the middle-tunnel shed expands the section clearance and the primary support section steel of the normal section in front of the middle-tunnel shed is smoothly installed.
6. The construction method for excavating the underground cave body of the crushed water-rich phyllite as claimed in claim 1, wherein: in the step (4), the grouting slurry can adopt cement-water glass double-liquid slurry or cement single-liquid slurry.
7. The construction method for excavating the underground cave body of the crushed water-rich phyllite as claimed in claim 1, wherein: in the step (6), the thickness of the primary sprayed concrete is 4 cm.
8. The construction method for excavating the underground cave body of the crushed water-rich phyllite as claimed in claim 1, wherein: in the step (7), the included angle between the two foot-contracting anchor pipes is 20 degrees, and the included angle between the foot-contracting anchor pipe positioned at the upper part and the lower part of the horizontal plane is 20 degrees.
9. The construction method for excavating the underground cave body of the crushed water-rich phyllite as claimed in claim 1, wherein: in the step of excavating the middle step and the lower step in the step (10), the footage of the middle step 11 and the lower step does not exceed two arch trusses every cycle of excavation, the front and the back of the excavation of the left side and the right side of the same step are staggered by 3 m-5 m, the front and the back of the excavation of the upper step and the lower step are staggered by 3 m-5 m, and two sides of the same arch truss cannot be suspended simultaneously.
10. The construction method for excavating the underground cave body of the crushed water-rich phyllite as claimed in claim 1, wherein: in the step (10), the inverted arch operation step is that construction is carried out immediately following the lower step, the footage is not more than 3m in each cycle, the excavation depth is marked on the inverted arch firstly during operation, mechanical layered excavation is adopted, the excavation depth is not too deep every time, the inverted arch is prevented from being overetched, inverted arch looping is completed in time after excavation, seepage water in the range of the hole body needs to be collected and pumped out before excavation, and accumulated water cannot soak the inverted arch or arch springing.
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| CN111577331A (en) * | 2020-05-13 | 2020-08-25 | 四川省交通勘察设计研究院有限公司 | Construction method of expressway steep-dip phyllite IV-V-level surrounding rock tunnel |
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| CN103628889A (en) * | 2013-11-28 | 2014-03-12 | 中铁十三局集团有限公司 | Quick sealing method for excavating phyllite stratum tunnel |
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