CN111502696A - Dense-mesh type advanced support system of underground excavation tunnel and construction method - Google Patents

Dense-mesh type advanced support system of underground excavation tunnel and construction method Download PDF

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Publication number
CN111502696A
CN111502696A CN202010252994.1A CN202010252994A CN111502696A CN 111502696 A CN111502696 A CN 111502696A CN 202010252994 A CN202010252994 A CN 202010252994A CN 111502696 A CN111502696 A CN 111502696A
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CN
China
Prior art keywords
tunnel
pipe
grouting
excavation
dense
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Pending
Application number
CN202010252994.1A
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Chinese (zh)
Inventor
程韬
郭洋洋
张冀
蒲东均
有智慧
陈健
杜林�
曹亚博
李坤哲
谢凯
杜志涛
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Guangzhou Metro Design and Research Institute Co Ltd
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Guangzhou Metro Design and Research Institute Co Ltd
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Application filed by Guangzhou Metro Design and Research Institute Co Ltd filed Critical Guangzhou Metro Design and Research Institute Co Ltd
Priority to CN202010252994.1A priority Critical patent/CN111502696A/en
Publication of CN111502696A publication Critical patent/CN111502696A/en
Pending legal-status Critical Current

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    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/04Lining with building materials
    • E21D11/10Lining 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
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21DSHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/14Lining predominantly with metal
    • E21D11/15Plate linings; Laggings, i.e. linings designed for holding back formation material or for transmitting the load to main supporting members
    • E21D11/152Laggings made of grids or nettings

Abstract

A dense-mesh type advanced support system of an underground excavated tunnel and a construction method for supporting by using the system are disclosed, the system comprises grouting sleeve valve pipes and a pipe shed, grouting is carried out on a front tunnel face and surrounding rocks of subsequent excavation by adopting the grouting sleeve valve pipes, then the dense-mesh type pipe shed is arranged to serve as a support, and the surrounding rocks at the top of an excavated section are supported by the pipe shed. And (4) arranging a small advanced guide pipe in the pipe shed gap, and reinforcing the rock and soil strength near the inner side surface of the tunnel through the small advanced guide pipe. The invention is more suitable for the subsurface excavation construction operation of the sandy gravel stratum, and effectively utilizes the self skeleton action of the sandy gravel stratum by adding the dense net type pipe shed and grouting.

Description

Dense-mesh type advanced support system of underground excavation tunnel and construction method
Technical Field
The invention relates to the technical field of underground engineering, in particular to a dense-mesh type advanced support system of an underground excavation tunnel and a dense-mesh type advanced support construction method of the underground excavation tunnel.
Background
With the rapid development of economy in China, underground engineering scales are rapidly expanded and connected into nets in order to adapt to the development and construction of modern cities. In order to avoid the influence on the ground environment and traffic, the underground excavation tunnel engineering is gradually the main construction method of urban underground engineering.
When underground excavation tunnel construction is carried out in a city, the situations of underpass of important building structures, existing subway lines, scenic spots, historic sites and the like are frequently met, so that extremely high requirements are put forward for stratum settlement control, and advance pre-support needs to be carried out on the underpass range before the underpass of underground excavation so as to realize settlement control.
At present, the existing underground excavation advance pre-supporting measures mainly comprise two measures: 1. the general method for the large pipe shed support construction comprises the following steps: before tunneling, a geological drilling machine is used for drilling horizontal holes in the vault area according to the designed hole number, space and depth, steel pipes with holes pre-drilled on the pipe walls are buried, and then cement slurry is injected to improve the rigidity of the steel pipes and reinforce soil; 2. the method is characterized in that the method comprises the steps of advancing small guide pipe support, wherein the advance small guide pipe support construction is similar to large pipe shed support construction, the method is suitable for underground excavation of a mine tunnel, and in the advance small guide pipe support construction, advanced grouting steel pipes are arranged at the arch crown every few steel frames according to design requirements.
The two forepoling forms are all that the vault of the tunnel is preformed into an umbrella-shaped structure, and the canopy frame supporting effect is achieved on the stratum. The large pipe shed and the advanced small conduit support are generally arranged at intervals of 250-350 mm in a circumferential direction, and the self rigidity of the steel pipe is utilized to support the upper surrounding rock and the load of the building structure. If an important building with a large load and a high requirement on settlement control is encountered, the pipe diameter of the pipe shed is often required to be increased or a multi-row pipe advancing mode is adopted, so that the problems of prolonged construction period, high use amount of advancing materials, poor supporting effect and the like are caused.
In summary, how to solve the problem of poor supporting effect of the single-form supporting method in the existing underground excavation advance pre-supporting measures under the use conditions of large load and high sedimentation control requirement becomes a problem to be solved urgently by the technical staff in the field.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides the following technical scheme:
the invention provides a dense-mesh type advanced support system of an underground excavation tunnel, which has the following specific structure: a tunnel excavation contour line and a full-section deep-hole pre-grouting outer contour line are designed on the excavation section of the tunnel, and the tunnel excavation contour line is positioned in the full-section deep-hole pre-grouting outer contour line; the support system includes: one end of each grouting sleeve valve pipe is positioned on an excavation section, the other end of each grouting sleeve valve pipe extends towards the tunneling direction of the tunnel, and one end of each grouting sleeve valve pipe is distributed in the tunnel excavation contour line; and the pipe sheds are positioned between the tunnel excavation contour lines and the full-section deep-hole pre-grouting outer contour lines and form a dense-net type pipe shed.
Preferably, in the dense-mesh type advance support system provided by the present invention, further comprising: the advanced small guide pipes are located between the tunnel excavation contour lines and the full-section deep-hole pre-grouting outer contour lines and used for reinforcing rock and soil close to the inner side face of the tunnel.
Preferably, in the dense-mesh type advance support system provided by the invention, a plurality of pipe sheds are arranged on the periphery of the arc of the tunnel arch to form a single-row pipe shed; in the single-row pipe sheds, the distances from the pipe sheds to the arc of the arch part of the tunnel are the same; the single-row pipe shed is provided with at least two groups, the distance from the pipe shed to the arc of the tunnel arch in each single-row pipe shed is different, and the pipe sheds in the two adjacent groups of single-row pipe sheds are arranged in a staggered mode.
Preferably, in the dense-mesh type advance support system provided by the invention, the dense-mesh type advance support system further comprises a grout stopping wall, and the grout stopping wall is arranged at the starting end of each tunneling section.
Preferably, one end of the pipe shed is fixedly connected with the grout stopping wall, and an included angle of 1-3 degrees is formed between the axis of the pipe shed and the central line of the tunnel.
Preferably, the dense-mesh type advance support system provided by the invention further comprises steel frames, and the steel frames are arranged at intervals in the excavated tunnel along the tunneling direction of the tunnel.
Preferably, one end of the advanced small guide pipe is located on an excavation section and takes the steel frame as a fulcrum, and an included angle of 15-25 degrees is formed between the axis of the advanced small guide pipe and the central line of the tunnel.
Preferably, in the dense-mesh type advanced support system provided by the invention, a steel reinforcement cage is arranged in the pipe shed, pipe shed grout overflow holes are formed in the pipe shed, the pipe shed grout overflow holes are uniformly distributed in the pipe shed, small guide pipe grout overflow holes are formed in the advanced small guide pipes, and the small guide pipe grout overflow holes are uniformly distributed in the advanced small guide pipes.
Preferably, in the dense-mesh type advanced support system provided by the invention, the reinforcement cage comprises a round-tube-shaped reinforcement cage framework and a plurality of reinforcements arranged on the outer side surface of the reinforcement cage framework, and all the reinforcements are arranged on the outer side surface of the reinforcement cage framework at equal intervals.
Preferably, in the dense-mesh type advance support system provided by the invention, one end of the grouting sleeve valve pipe is positioned on the grout stop wall, the grouting sleeve valve pipe is arranged around the central line of the tunnel at intervals, one end of the grouting sleeve valve pipe is fixed, and the other end of the grouting sleeve valve pipe is arranged in a divergent manner relative to the central line of the tunnel.
The invention also provides a dense-mesh type advanced support construction method of the underground excavation tunnel, which comprises the following operations: constructing a grout stop wall, arranging a full-face grouting sleeve valve pipe in the outline of the excavated section of the tunnel, and grouting in advance to reinforce the stratum so as to stabilize the excavated section; erecting the steel frame at the excavation section of the tunnel; arranging a pipe shed; and an advanced small conduit is arranged in the gap of the pipe shed by taking the steel frame as a fulcrum.
Preferably, in the close-mesh type advanced support construction method of the underground excavated tunnel provided by the invention, a tunnel excavation contour line and a full-section deep-hole pre-grouting outer contour line are designed on the excavation section of the tunnel; arranging the grouting sleeve valve pipes into the tunnel excavation contour lines, and performing full-face grouting reinforcement on the areas in the tunnel excavation contour lines through the grouting sleeve valve pipes; and arranging the pipe shed in an area between the tunnel excavation contour line and the full-section deep hole pre-grouting outer contour line, and forming a dense-net type pipe shed.
The invention has the following beneficial effects:
the invention provides a dense-mesh type advanced support system for an underground excavated tunnel, which comprises grouting sleeve valve pipes and pipe sheds, wherein grouting is carried out on a front tunnel face and surrounding rocks of subsequent excavation by adopting the grouting sleeve valve pipes, then a plurality of rows of dense-mesh type pipe sheds are arranged along with pipes to serve as supports, and the surrounding rocks at the top of an excavated section are supported by the pipe sheds. And (4) arranging a small advanced guide pipe in the pipe shed gap, and reinforcing the rock and soil strength near the inner side surface of the tunnel through the small advanced guide pipe. Compared with the prior art, the invention is more suitable for the subsurface excavation construction operation of the sandy gravel stratum, the self skeleton action of the sandy gravel stratum is effectively utilized by adding the dense net type pipe shed and grouting, and compared with the subsurface excavation engineering under the sandy gravel stratum in the prior art, the invention effectively controls the stratum settlement, limits the occurrence of the excavation over-square condition, simultaneously has no limit on the excavation length in the construction, saves the construction cost, ensures the safety of the construction and the surrounding buildings, and provides a powerful guarantee for the safety construction of the urban subsurface excavation engineering.
The invention also provides a dense-mesh type advanced support construction method of the underground excavated tunnel, wherein in the support construction method, the excavation area is reinforced by grouting at first; then arranging a pipe shed; then a small leading conduit is arranged in the gap of the pipe shed. The dense-net type advanced support construction method for the underground excavation tunnel is used for underground excavation underpass engineering, is particularly suitable for underground excavation engineering under a sandy gravel stratum, and can construct a dense-net type advanced support. According to the invention, through a grouting mode, the tunnel face in front of the excavation face can be effectively stabilized, meanwhile, effective support can be provided for the pipe shed, and through a dense net type pipe shed support, a support framework can be provided for the stratum and grouting can be carried out, so that the self stability of the surrounding rock can be better utilized. The small advanced guide pipe is arranged below the pipe shed and in surrounding rocks between sheds, so that the over-excavation can be reduced, and a complete advanced support system is formed. Practice proves that compared with the prior construction technical scheme, the invention saves the construction cost and has safer and more reliable support.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. Wherein:
FIG. 1 is a schematic view of a section of a grouting area;
FIG. 2 is a schematic diagram of an arrangement mode of grouting sleeve valve pipes on an excavation section;
FIG. 3 is a longitudinal schematic view of a grouting sleeve valve tube arrangement;
FIG. 4 is a schematic structural view of a single pipe shed in the present invention;
FIG. 5 is a schematic view of the arrangement of the pipe shed and the small leading pipes in the excavation section according to the present invention;
FIG. 6 is a longitudinal view of the tube shed and the leading small tube arrangement of the present invention;
FIG. 7 is a radial view of the reinforcement cage of the present invention;
FIG. 8 is an axial view of the reinforcement cage of the present invention;
FIG. 9 is a schematic diagram of grouting range of grouting reinforcement when a building with a height of five stories is penetrated by the grouting reinforcement in the embodiment of the invention;
FIG. 10 is a schematic view of a grouting range of grouting reinforcement when a bridge is traversed according to an embodiment of the invention;
FIG. 11 is a schematic diagram illustrating a grouting range for grouting reinforcement when passing through a flood drainage channel according to an embodiment of the present invention;
description of reference numerals:
the grouting sleeve valve pipe comprises a grouting sleeve valve pipe 1, a steel frame 2, a pipe shed 3, a small advanced guide pipe 4, a pipe shed working room 5, a reinforced steel plate 6, a drill bit 7, a reinforcement cage 8, a reinforcement cage framework 81, a reinforcement 82, a full-section deep-hole pre-grouting outer contour line 9, a tunnel excavation contour line 10, a grouting range 11, a primary support 12 and a secondary lining support 13;
building a with five floors, bridge pile foundation b and flood drainage channel c.
Detailed Description
The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. The various examples are provided by way of explanation of the invention, and not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. It is therefore intended that the present invention encompass such modifications and variations as fall within the scope of the appended claims and equivalents thereof.
In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are for convenience of description of the present invention only and do not require that the present invention must be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. The terms "connected" and "connected" used herein should be interpreted broadly, and may include, for example, a fixed connection or a detachable connection; they may be directly connected or indirectly connected through intermediate members, and specific meanings of the above terms will be understood by those skilled in the art as appropriate.
Please refer to fig. 1 to 11, wherein fig. 1 is a schematic diagram of a section of a grouting range; FIG. 2 is a schematic diagram of an arrangement mode of grouting sleeve valve pipes on an excavation section; FIG. 3 is a longitudinal schematic view of a grouting sleeve valve tube arrangement; FIG. 4 is a schematic structural view of a single pipe shed in the present invention; FIG. 5 is a schematic view of the arrangement of the pipe shed and the small leading pipes in the excavation section according to the present invention; FIG. 6 is a longitudinal view of the tube shed and the leading small tube arrangement of the present invention; FIG. 7 is a radial view of the reinforcement cage of the present invention; FIG. 8 is an axial view of the reinforcement cage of the present invention; FIG. 9 is a schematic diagram of grouting range of grouting reinforcement when a building with a height of five stories is penetrated by the grouting reinforcement in the embodiment of the invention; FIG. 10 is a schematic view of a grouting range of grouting reinforcement when a bridge is traversed according to an embodiment of the invention; fig. 11 is a schematic view illustrating a grouting range for grouting reinforcement when passing through a flood discharge canal according to an embodiment of the present invention.
The scale of urban underground engineering is rapidly expanded and connected into a net, so that in order to avoid influences on ground environment and traffic, underground excavation tunnel engineering is increasingly used as a main construction method of urban underground engineering, the key problems to be solved by the underground excavation engineering are that the safety of the underground excavation construction is ensured, and the influence of the underground excavation engineering on surrounding building structures is reduced.
Therefore, the invention discloses a dense-mesh type advanced support system of an underground excavation tunnel and a construction method. The invention is suitable for underground excavation engineering under a sandy gravel stratum, and in the support construction method, the invention can effectively stabilize a tunnel face (excavation section) in front of the excavation face in a grouting mode, and can provide a support framework for the stratum and perform grouting by supporting through the dense net type pipe shed 3, thereby better utilizing the self stability of surrounding rocks. The small advanced guide pipe 4 is arranged below the support of the pipe shed 3 and in surrounding rocks between sheds to form a complete advanced support system, and pre-grouting reinforcement is carried out to ensure the stability of the excavation section structure and reduce overexcavation. Practice proves that compared with the prior construction technical scheme, the invention saves the construction cost and has safer and more reliable support.
For a better and detailed explanation of the invention, the following is made: a tunnel excavation contour line 10 and a full-section deep-hole pre-grouting outer contour line 9 are designed on an excavation section of the tunnel, and the tunnel excavation contour line 10 is positioned in the full-section deep-hole pre-grouting outer contour line 9; the tunnel is excavated mechanically or manually, and the top of the tunnel is of an arc vault structure; the tunnel center line refers to a connecting line of the centers of circular arc vaults of vertical sections of the tunnel, and the length direction of the connecting line (the tunnel center line) is consistent with the depth direction of the tunnel.
The invention provides a dense-mesh type advanced support system of an underground excavation tunnel, and particularly provides the dense-mesh type advanced support system of the underground excavation tunnel, which comprises the following components:
1. grouting sleeve valve pipe 1
Grouting sleeve valve pipe 1 is used for opening and digs the regional slip casting and consolidate, and 1 slip casting system of slip casting sleeve valve pipe is applicable to the undercut engineering, and it can control slip casting scope 11 and slip casting pressure, can also avoid the thick liquid backward flow simultaneously, guarantees construction quality.
In the invention, the grouting sleeve valve tube 1 is adoptedHard PVC pipe.
Specifically, one end of the grouting sleeve valve pipe 1 is located on the excavation section and used for being connected with a grouting system, concrete slurry is pumped into the grouting sleeve valve pipe 1 through the grouting system, and the other end of the grouting sleeve valve pipe 1 extends towards the tunneling direction of the tunnel.
The grouting sleeve valve pipe 1 is used for full-face grouting reinforcement in a full-face deep hole pre-grouting outer contour line 9, and the full-face grouting reinforcement range covers a tunnel excavation contour line 10.
The grouting sleeve valve pipe is also provided with a grout stopping wall, and the grout stopping wall is used for being matched with the grouting sleeve valve pipe 1. Specifically, the grout stopping wall is arranged at the starting end of the tunneling section and used for realizing water stopping and grout stopping before tunnel excavation and ensuring grouting reinforcement quality. In the tunnel excavation construction process, the tunnel is excavated in sections, the first grouting reinforcement is carried out when the first section of excavation is carried out, and a grout stopping wall is required to be used and is a plain concrete wall with the thickness of 300-500 mm. In the excavation of the subsequent section of the tunnel, the subsequent grouting operation utilizes the surrounding rock which is grouted in the range of about 3m from the tail end of the previous grouting reinforcement section as a grout stopping rock tray, and no additional grout stopping wall is needed.
Specifically, the grouting sleeve valve pipes 1 are arranged around the center line of the tunnel at intervals, one ends of the grouting sleeve valve pipes 1 are fixed, the other ends of the grouting sleeve valve pipes are arranged in a divergent mode relative to the center line of the tunnel, and the divergent structure of the grouting sleeve valve pipes 1 is similar to a spoke structure on an umbrella. The grouting sleeve valve pipes 1 are uniformly distributed on a plurality of circles with different radiuses, and the concrete arrangement of the grouting sleeve valve pipes 1 is subject to the guarantee that the farthest end grouting diffusion radiuses of the grouting sleeve valve pipes 1 can be pressed together. The grouting sleeve valve pipe 1 can be regarded as a cylinder, the diffusion radius of grouting is 1m, the farthest ends of the grouting sleeve valve pipe 1 are pressed together, and the pressing range is smaller as better.
Specifically, a grouting sleeve valve pipe is arranged at the center line of the tunnel, then the grouting sleeve valve pipes are arranged on a plurality of virtual circles with different radiuses by taking the grouting sleeve valve pipe as the center of a circle, and the radius values of all the virtual circles form a difference array from the first virtual circle to the outside. For example, the radius of the first virtual circle is 500mm, the radius of the second virtual circle is 1000mm, the radius of the third virtual circle is 1600mm, the radius of the fourth virtual circle is 2300mm, and the radius of the fifth virtual circle is 3100 mm. On each virtual circle, the grouting sleeve valve pipes 1 are arranged at equal intervals and consistent with the included angle between the central lines of the tunnels, so that the uniform pre-grouting reinforcement can be carried out in the outer contour lines of the section deep hole pre-grouting.
2. Pipe shed 3
The pipe shed 3 is provided to the tunnel upper portion, and can reinforce the tunnel upper structure. The vault of the tunnel is generally in a circular arc vault structure, and the structure (circular arc vault) can enable the vault of the tunnel to have better stress.
In the invention, the pipe shed 3 is arranged above the vault of the tunnel and is used for supporting and reinforcing the area outside the vault of the tunnel.
Specifically, the pipe shed 3 is arranged along the excavation heading direction, namely the length direction of the pipe shed 3 is consistent with the tunneling direction of the tunnel, and the plurality of pipe sheds 3 are positioned between the tunnel excavation contour line and the full-section deep-hole pre-grouting outer contour line and form a dense-net type pipe shed.
Furthermore, a plurality of pipe sheds 3 are arranged on the periphery of the arc of the tunnel arch part to form a single-row pipe shed, circle center connecting lines of all single pipe sheds 3 in the single-row pipe shed in the same vertical section are arc lines, and on the same arc line, the circumferential distance between every two adjacent pipe sheds 3 is 0.5 m; in the single-row pipe shed, the distances from the pipe sheds 3 to the tunnel arch (the vertical section of the tunnel arch is in the shape of a circular arc) are the same; the single pipe canopy of multiunit is arranged the setting in proper order to the direction of keeping away from the tunnel center by the tunnel hunch portion, and single pipe canopy of row is provided with at least two sets ofly, and every group single pipe canopy of row forms pitch arc (centre of a circle connecting wire in same vertical section) to the distance of tunnel hunch portion circular arc vary, and the crisscross setting of single pipe canopy 3 of adjacent two sets of single pipe canopies. When more than two groups of single-row pipe sheds are arranged, the vertical distances between the arcs (circle center connecting lines in the same vertical section) formed by the two adjacent groups of single-row pipe sheds are equal.
Further, in the pipe shed support, one end of the pipe shed 3 is fixed, and the pipe shed 3 has an included angle of 1 to 3 degrees (such as 1 degree, 1 degree 20 degrees, 1 degree 30 degrees, 1 degree 40 degrees, 2 degrees 20 degrees, 2 degrees 40 degrees, 3 degrees) with the central line of the tunnel in space. In the invention, the maximum included angle between the pipe shed 3 and the central line of the tunnel is 3 degrees, the included angle is selected to be 1-3 degrees, preferably 1-30' -3 degrees, the pipe shed 3 is ensured to be invaded to the tunnel excavation range when not being erected, and if the included angle between the pipe shed 3 and the central line of the tunnel is overlarge, the soil between the pipe shed and the tunnel excavation support steel frame is more when the pipe shed is longer, the soil amount is larger, the condition that the soil or broken stones cannot fall is ensured, if the soil (broken stones and the like) falls, the over-excavation occurs to cause backfilling, so the pipe shed is close to the excavation profile edge as much as possible, and the excavation profile is not invaded, and the included angle range of 1-3 degrees is formed between the pipe shed 3 and the central line of the tunnel by combining the practical application and the trimming of a designer.
In order to improve the structural strength of the pipe shed 3, the invention arranges a steel reinforcement cage in the pipe shed 3, the pipe shed 3 is provided with pipe shed grout overflow holes, the pipe shed grout overflow holes are uniformly distributed on the pipe shed 3, the advanced small guide pipe 4 is provided with small guide pipe grout overflow holes, and the small guide pipe grout overflow holes are uniformly distributed on the advanced small guide pipe 4.
Dense net type pipe shed 3 support and adoptThe seamless steel pipe of wall thickness 10mm, in same row, the hoop interval between two adjacent pipe sheds 3 is 500mm, and the length of pipe shed 3 is 35 m. The pipe shed 3 is formed by connecting a plurality of sections of steel pipes, two adjacent sections of steel pipes are connected by screw threads, two adjacent sections of steel pipes are welded annularly and then are longitudinally welded with reinforcing steel plates 6 along the steel pipe joints, the width of each reinforcing steel plate 6 is not less than 1/3 of the diameter of the pipe shed 3 (steel pipe), and the length of each reinforcing steel plate is not less than 1.5 times of the diameter of the steel pipe of the pipe shed 3. The pipe wall of the pipe shed 3 is provided with grouting holes with the longitudinal (length direction of the pipe shed 3) interval of 800mm, the grouting holes are arranged in a quincunx shape, 5 holes are arranged in a circumferential (radial) direction, and the size of each hole is 10 mm.
Specifically, the steel reinforcement cage 8 includes a round tube type steel reinforcement cage framework 81 and steel reinforcements 82 arranged on the outer side surface of the steel reinforcement cage framework 81, the steel reinforcements 82 are provided with a plurality of steel reinforcements, and all the steel reinforcements 82 are arranged on the outer side surface of the steel reinforcement cage framework 81 at equal intervals.
The steel reinforcement cage framework 81 is a steel pipe with an outer diameter of 45mm and a wall thickness of 3.0 mm. The reinforcing steel bars 82 are fixedly connected with the reinforcement cage framework 81 in a welding mode.
3. Advanced small catheter 4
The advanced small pipe 4 is matched with the pipe shed 3 for use, and the plurality of advanced small pipes 4 are positioned between the tunnel excavation contour line and the full-section deep-hole pre-grouting outer contour line and used for reinforcing rock soil close to the inner side surface of the tunnel.
The advanced small catheter 4 adoptsThe wall thickness of the seamless steel pipe with the thickness of 2.5mm is 2.5m, the longitudinal (the length direction of the advanced small guide pipe 4) interval of grouting holes formed in the pipe wall is 200mm, the circumferential (radial) interval is 40mm, and the size of the hole is 8 mm. The front end of the leading small pipe 4 is tapered to facilitate plunging and prevent slurry from rushing forward. The small advanced guide pipes 4 are longitudinally arranged at intervals of 1.5 degrees obliquely upwards by taking the steel frame 2 as a fulcrum, are annularly arranged in the gaps of the pipe sheds 3, and the pipe ends exceed the outer part of the steel frame 2 by 10cm so as to be convenient for connecting grouting pipes.
18-shaped steel or grid steel frames are adopted for the steel frames 2, the distance between the steel frames 2 (the distance along the depth direction of the tunnel) is 0.5m, and reinforcing meshes are additionally arranged on the inner side and the outer side of each steel frame 2 for mesh spraying.
The invention also provides steel frames 2, the steel frames 2 are arranged at intervals in the excavated tunnel along the tunneling direction of the tunnel, one end of the advanced small conduit 4 is fixedly connected with the steel frames 2, and an included angle of 15-25 degrees (such as 15 degrees, 16 degrees, 17 degrees, 18 degrees, 19 degrees, 20 degrees, 21 degrees, 22 degrees, 23 degrees, 24 degrees and 25 degrees) is formed between the axis of the advanced small conduit 4 and the central line of the tunnel. The included angle between the axis of the leading small conduit 4 and the tunnel center line is determined according to the distance between the steel frames 2, if the distance between the steel frames 2 is 0.5m, the included angle between the leading small conduit 4 and the tunnel center line is 15-25 degrees during actual operation, so that the leading small conduit cannot reach the range of the front steel frame 2, and the erection of the steel frame 2 is not influenced.
The invention realizes the fixation of the pipe shed 3 and the advanced small pipe 4 by the following modes: the invention adopts a full-face grouting sleeve valve pipe 1 grouting mode, can reinforce the stratum and provides a supporting fulcrum for the dense-net type pipe shed 3, wherein the supporting fulcrum refers to the soil which is not excavated in front and is reinforced by grouting through the full-face grouting sleeve valve pipe 1, and the reinforced soil and the excavated and erected steel frame 2 form two fulcrums to play a role of carrying a shoulder pole; a steel frame 2 is arranged in an excavated tunnel, the end part of the advanced small guide pipe 4 is welded and fixed with the steel frame 2, and the steel frame 2 can be used as a fulcrum of the advanced small guide pipe 4.
Before actual construction, the tunnel excavation contour line and the full-section deep hole pre-grouting outer contour line of the tunnel are designed, the trend of the excavated tunnel, the structural size of the tunnel and the like are determined, tunneling is carried out according to determined data, and then the excavation section is determined, namely the area contained by the tunnel excavation contour line. According to the invention, full-section grouting is carried out according to the excavated section, wherein the full section refers to the cross section of a tunnel (not excavated), and the full-section grouting refers to the grouting range 11 covering the whole tunnel section.
And adopting a grouting sleeve valve pipe 1 for grouting to reinforce the front face and surrounding rocks of the subsequent excavation, then arranging a plurality of rows of dense net type pipe sheds 3 along with the pipe to serve as supports, and supporting the surrounding rocks at the top of the excavation section through the pipe sheds 3. And leading small pipes 4 are arranged in the gaps of the pipe sheds 3, and the rock-soil strength near the inner side surface of the tunnel is reinforced through the leading small pipes 4. After the tunnel is excavated, the steel frame 2 is erected in the tunnel in time, the advanced small guide pipe 4 is erected after the steel frame 2 is erected, and the advanced small guide pipe 4 is welded with the steel frame 2. And then reinforcing meshes are additionally arranged on the inner side and the outer side of the steel frame 2, and concrete is sprayed on the meshes to form a stable supporting surface. After the construction of one tunneling section is completed, the pipe shed working chamber 5 is excavated, and then the circular construction is performed according to the above mode until the construction of the underground tunnel is completed.
For the construction, the specific requirements are as follows: 1. a grouting sleeve valve pipe 1 is longitudinally arranged in the tunnel, cement slurry is injected into the stratum through the grouting sleeve valve pipe 1, and the grouting diffusion radius of the single grouting sleeve valve pipe 1 is not less than 1 m; 2. the pipe sheds 3 are arranged at intervals of 500mm in a dense net mode, reinforcing cages 8 are placed in each pipe shed 3 after the pipe sheds 3 are arranged, cement paste is injected into each pipe shed 3, and the pipe sheds 3 and peripheral sand pebbles form an integral supporting system.
The longitudinal direction of the tunnel is the heading direction of the tunnel, or is understood to be the depth direction of the tunnel.
The leading small catheter 4 is fixed in the following way: after a tunnel (a certain section) is excavated, a steel frame 2 is arranged in the tunnel, then an advanced small guide pipe 4 is arranged, the advanced small guide pipe 4 is welded with the steel frame 2, reinforcing meshes are additionally arranged on the inner side and the outer side of the steel frame 2, and concrete is sprayed, so that the arranged advanced small guide pipe 4 and the steel frame 2 can form a shell support for supporting surrounding rocks between the lower part of a pipe shed 3 and the excavation outline.
Specifically, the section is excavated, a steel frame 2 is erected in time, then a small advanced guide pipe 4 is arranged at intervals, the section is excavated to the next pipe shed working chamber 5 in a circulating mode, and a next circulating dense-net type advanced support system is arranged according to the construction procedure of the previous excavation section.
Referring to fig. 5, in the vertical section of the excavated tunnel, the excavation range of the pipe shed working chamber 5 should cover the arrangement range of the pipe shed 3 and the advanced small ducts 4, and a primary support 12 and a secondary support 13 are arranged outside the outer contour of the pipe shed working chamber 5.
Compared with the prior art, the invention is more suitable for the subsurface excavation construction operation of the sandy gravel stratum, the self skeleton action of the sandy gravel stratum is effectively utilized by adding the dense net type pipe shed 3 and grouting, compared with the subsurface excavation engineering under the sandy gravel stratum in the prior art, the invention effectively controls the stratum settlement, limits the occurrence of the excavation over-square condition, simultaneously, the excavation length in the construction is not limited, the construction cost is saved, the safety of the construction and the surrounding buildings is ensured, and the invention provides powerful guarantee for the safety construction of the urban subsurface excavation engineering.
To facilitate the description of the construction operation of the present invention, it is explained here that: in the underground excavation engineering, a tunnel body structure formed by tunneling according to a tunnel excavation contour line is taken as a tunnel; during tunneling, a tunneling surface in the tunnel is a tunnel face; the working surface formed by combining the area around the tunnel excavation contour line and the tunnel face is an excavation section. The section of the pipe shed working room 5 is larger than the tunnel face of a common section, so that a larger operation space (the pipe shed working room 5) can be provided, and construction operation is facilitated.
The dense-mesh type advanced support system of the underground excavation tunnel is used for supporting underground excavation underpass engineering, and is particularly suitable for underground excavation engineering under a sandy gravel stratum. In the supporting system, the invention can effectively stabilize the tunnel face in front of the excavation face in a grouting mode and can provide effective support for the pipe shed 3. According to the invention, the dense net type pipe shed 3 is arranged to provide a support framework for the stratum and grouting is carried out, so that the stability of the surrounding rock can be better utilized. After the pipe shed 3 is arranged, surrounding rocks below the pipe shed 3 and among the sheds can be stabilized by arranging the advanced small guide pipes 4, and overexcavation is reduced, so that a set of advanced support system is formed. Compared with the prior construction technical scheme, the invention saves the construction cost and is safer and more reliable.
The invention also provides a dense-mesh type advanced support construction method of the underground excavation tunnel, which is applied to underground excavation engineering, in particular to underground excavation engineering of sandy gravel stratum.
The invention provides a dense-mesh type advanced support construction method of an underground excavation tunnel, which mainly comprises the following construction steps: step one, constructing a grout stop wall; secondly, grouting and reinforcing the excavated area; step three, arranging a pipe shed 3; and step four, arranging a small advanced guide pipe 4 in the gap of the pipe shed 3.
Specifically, in step two: and (3) driving a grouting sleeve valve pipe 1 according to the outline of the excavated section, and performing full-section grouting reinforcement on the excavated section through grouting of the grouting sleeve valve pipe 1.
The grouting sleeve valve pipe 1 is a grouting tool, can well control the grouting range 11 and the grouting pressure, can perform repeated grouting, and has low possibility of causing grout leakage and grout string. The full-section grouting sleeve valve pipe 1 is arranged according to the contour of the excavated section, namely the grouting sleeve valve pipes 1 for grouting are uniformly arranged in the tunnel face, the grouting sleeve valve pipes 1 are obliquely arranged relative to the center line of the tunnel, and the center line of the tunnel, namely the connecting line of the circle centers of the arc arches of the tunnel, is parallel to the tunneling direction of the tunnel, so that grouting can be performed in the tunnel (not excavated) and the surrounding area of the tunnel, and the reinforcement of the tunnel face and the surrounding area of the tunnel face is achieved. The invention can strengthen the stratum to stably excavate the tunnel face by grouting in advance. Meanwhile, the surrounding area of the tunnel face is reinforced, so that the surrounding geotechnical structures of the tunnel face can provide a front stable fulcrum of the dense-net type pipe shed 3 in the subsequent engineering.
In the construction method of the dense-mesh type advanced support of the underground excavated tunnel, a pipe shed support is arranged in the third step.
Specifically, in step three: pipe shed 3 sets up in the upper portion of tunnel excavation contour line, the upper portion of tunnel vault circular arc promptly, and pipe shed 3 lays according to the shape of tunnel vault circular arc upper portion on it, and pipe shed 3 is provided with two rows at least, and each calandria canopy 3 is outwards range upon range of setting from tunnel vault circular arc.
In general, the arc of the vault of the tunnel is a smooth arc-shaped curve, then, according to the tunnel excavation contour line, a row of pipe sheds 3 arranged at equal intervals are arranged on the upper portion of the tunnel excavation contour line and at a certain distance away from the tunnel excavation contour line along a smooth curve (virtual), then, a second pipe shed 3 is arranged in the outer area of the first pipe shed 3, and according to the stratum structure and the design requirements, multiple layers (including two layers) of pipe sheds 3 can be arranged for excavation, reinforcement and support.
It should be noted that: in the same calandria shed 3, the vertical distance from the calandria shed 3 to the tunnel excavation contour line is the same.
In the third step, the invention aims to provide a dense net type pipe shed support. In the pipe shed support constructed by the invention, the pipe sheds 3 are arranged in a vertically crossed manner to form a dense-mesh structure system, namely, in two adjacent rows of pipe sheds 3, the pipe shed 3 on the outer layer is positioned in the middle position of two adjacent pipe sheds 3 on the inner layer.
In a specific embodiment of the invention, the dense-net type pipe sheds 3 are supported and arranged in two rows above the arch crown of the tunnel, the two rows of pipe sheds 3 are arranged in a staggered mode to form a net shape, and pipe shed grout overflow holes are formed in the pipe walls of the pipe sheds 3 in a quincunx mode. In same one row of pipe shed 3, the 3 hoop intervals of two adjacent pipe sheds are the optimum and are 0.5m, certainly, can suitably reduce 3 hoop intervals of pipe shed or increase 3 hoop intervals of pipe shed according to ground characteristics.
Pipe shed 3 is provided with a pipe shed grout overflow hole, and a drill bit 7 is arranged at the end part of pipe shed 3, so that pipe shed 3 can be driven conveniently. After pipe shed 3 is squeezed into the stratum, set up steel reinforcement cage 8 in pipe shed 3, then to pipe shed 3 slip casting, the thick liquid of part slip casting overflows and links into an entirety with the stratum between pipe shed 3 and pipe shed 3 through 3 wall grout holes of pipe shed, and pipe shed 3 sets up and can regard as stratum structure skeleton in the stratum.
The specific layout of the pipe shed 3 includes the following two types: 1. one end of the pipe shed 3 is fixed, the lifting angle of the other end of the pipe shed 3 relative to the horizontal plane is consistent, and an included angle of 1-3 degrees is formed between the pipe shed 3 and the central line of the tunnel; 2. one end of the pipe shed 3 is fixed, the other end of the pipe shed 3 is consistent in lifting angle relative to the tangent plane of the tunnel roof arc, and an included angle of 1-3 degrees is formed between the pipe shed 3 and the center line of the tunnel.
Before the operation is carried out, the invention also provides a step I of constructing the grout stopping wall, wherein the grout stopping wall is used for preventing overflow and grout overflow. In the invention, the full-section grouting sleeve valve pipe 1 needs to be used as a plain concrete grout stop wall with the thickness of 300-500 mm on the underground excavated tunnel face during grouting, and the grout stop wall can also be used as a guide wall of a subsequent pipe shed 3 and a support structure of the pipe shed 3.
Embedding in the grout stop wall according to the arrangement mode of the grouting sleeve valve pipe 1The seamless steel tube is used as an orifice tube, and the length of the orifice tube is 1.5 m. Grouting sleeve valve pipe 1 adoptsThe rigid PVC pipe is required to bear the maximum pressure of more than 3.0MPa, grouting pipe grouting holes are formed in the pipe wall of the grouting sleeve valve pipe 1, the opening intervals of the grouting pipe grouting holes are arranged according to a 300mm quincunx shape, a rubber sleeve is tightly hooped outside the opening, and the grouting pipe grouting holes are covered by the rubber sleeve. The bottom end of the grouting sleeve valve pipe 1 is tightly wrapped and tied by geotextile and other objects, so that sleeve shell materials are prevented from entering the grouting sleeve valve pipe 1.
During grouting and reinforcing, pure cement slurry (cement slurry-water glass double-liquid slurry is adopted when precipitation is difficult) is adopted. Namely: and during grouting reinforcement, cement slurry is adopted for grouting, the ratio of water to cement in the cement slurry is 0.8: 1, a composite water reducing early strength agent with the cement dosage of 0.3-0.5% can be added into the cement slurry, and the grouting pressure is 1.0-1.5 MPa.
In the second step: the grout for grouting reinforcement has a diffusion radius of not less than 1.0m, and the diffusion ranges of the farthest grouting sleeve valve pipes 1 for grouting reinforcement are not less than 0.2m through mutual engagement. Namely: the grout diffusion radius is not less than 1.0m, the driving angle and the position of the grouting sleeve valve pipe 1 are adjusted according to the section and the operation space, and the grouting diffusion ranges of the grouting sleeve valve pipes 1 at the farthest position are guaranteed to be mutually occluded by not less than 0.2 m.
In step four, a leading small pipe 4 is arranged in the gap of the pipe shed 3.
Further, in order to reinforce the tunnel and support the advanced small guide pipes 4, the steel frames 2 are arranged along the longitudinal direction of the excavation section, and the steel frames 2 are arranged at intervals along the length direction of the tunnel. Wherein, the one end and the steelframe 2 fixed connection of little pipe 4 in advance, along the excavation tunnelling direction, the other end of little pipe 4 in advance keeps away from the tunnel central line, has the contained angle of 15 ~ 25 between the axis of little pipe 4 in advance and the tunnel central line.
The small ducts are arranged at intervals in front of the small ducts along the arrangement direction of the steel frames 2. The arrangement of the advanced small conduit 4 at intervals specifically comprises the following steps: the advanced small guide pipe 4 is connected with a steel frame 2 (assumed as a first steel frame), and the next advanced small guide pipe 4 is connected with the next steel frame 2 (assumed as a third steel frame) after passing through a steel frame (assumed as a second steel frame) along the depth direction of the tunnel.
For the tunnel which is well excavated, the steel frame is arranged in the tunnel and is used for realizing the support and the support of the tunnel in the initial stage. After the tunnel is excavated, concrete is sprayed firstly, the thickness of the concrete is about 35mm, then the net is hung, a steel frame is erected, the operation of erecting the steel frame comprises the steps of arranging the steel frame, arranging longitudinal connecting ribs, anchor rods and the like, and immediately, the concrete is continuously sprayed to the designed thickness after the steel frame is erected.
During excavation and tunneling, a steel frame 2 is arranged in a dug tunnel, the tunnel is reinforced by the steel frame 2, and meanwhile, a 2.5 m-long advanced small guide pipe 4 is arranged between pipe sheds 3 by taking the steel frame 2 as a fulcrum. The leading small conduit 4 is arranged in the pipe shed 3 at an angle of 1.5 degrees, and the pipe wall is provided with grouting holes according to a quincunx shape for grouting.
Specifically, in step three: when the pipe shed 3 is arranged, the pipe shed 3 is constructed by adopting pipe jacking, the pipe shed 3 is subjected to grouting, cement paste grouting is adopted when the pipe shed 3 is grouted, the ratio of water to cement to sand in the cement paste is 0.8: 1, the grouting pressure is 1.0MPa, and the pipe is well exhausted to ensure compact filling.
In step four: after the leading small guide pipe 4 is arranged, grouting is carried out on the leading small guide pipe 4, cement-water glass double-liquid slurry is adopted when the leading small guide pipe 4 is grouted, the ratio of the slurry is W to C which is 1 to 1, the ratio of C to S which is 1 to 1 (volume ratio), and the grouting pressure is 0.5-1.0 MPa. Wherein W is water, C is cement, and S is water glass.
When grouting reinforcement, cement paste is adopted, the water cement ratio is 0.8: 1, a composite water-reducing early strength agent with the cement dosage of 0.3-0.5% can be added into the cement paste, the grouting pressure is 1.0-1.5 MPa, the single-hole grouting pressure reaches the design final pressure and grouting continues for more than ten minutes or the single-hole grouting amount is approximately the same as the design grouting amount, and the hole grouting can be finished.
In the dense-net type pipe shed 3 support, the pipe shed 3 is constructed by jacking with a pipe, a reinforcement cage 8 is placed after the construction is finished, and the reinforcement cage 8 is formed by one reinforcement cage4 steel pipes with the wall thickness of 3.0mm are welded on the periphery of the frameworkAnd (3) forming reinforcing steel bars, and then pouring cement paste by adopting a retreating process, namely inserting the grouting sleeve valve pipe 1 to the farthest end of the pipe shed 3, and then grouting while retreating the pipe, so that the filling flow of the pipe can be compact. The ratio of water to lime to sand is 0.8: 1, the grouting pressure is 1.0MPa, and the air is exhausted from the pipe to ensure the compact filling.
The advanced small conduit 4 adopts cement-water glass double-liquid slurry for grouting, the ratio of the slurry is W to C is 1 to 1, the ratio of C to S is 1 to 1 (volume ratio), and the grouting pressure is 0.5 MPa-1.0 MPa.
Please refer to fig. 9 to fig. 11. In the actual construction process of the invention, the grouting range 11 for grouting reinforcement should not affect the existing building, or the outermost edge of the grouting range 11 just contacts with the foundation structure or pile foundation structure of the existing building (the just contact here means a small-range contact), so that reinforcement can be achieved without affecting the existing building.
For example, in fig. 9, when the tunnel passes through the building a with five stories, the grouting range 11 is designed according to the construction range of the foundation of the building a with five stories, so that the grouting range 11 is positioned below the foundation of the building a with five stories, and the outermost edge of the grouting range 11 is just contacted with the outermost layer of the foundation.
For example, in fig. 10, when a tunnel passes through the bridge, the bridge is a viaduct, the bridge body is supported by the bridge pile foundations b, the bridge pile foundations b have a certain depth of penetration, the grouting range 11 is designed according to the arrangement mode of the bridge device b on the ground surface and the depth of penetration, and it is ensured that when the tunnel passes through the bridge, the grouting range 11 can cover all the bridge pile foundations b above the tunnel, and the outermost edge of the grouting range 11 just contacts with the lower portion of the bridge pile foundations b.
For example, in fig. 11, when the tunnel passes through the flood discharge channel c, the bottom of the flood discharge channel c is a concrete foundation, and the grouting range 11 is completely below the concrete foundation and does not contact with the concrete foundation.
The above is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made to the present invention by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A dense-net type advanced support system of an underground excavation tunnel is characterized in that,
a tunnel excavation contour line and a full-section deep-hole pre-grouting outer contour line are designed on the excavation section of the tunnel, and the tunnel excavation contour line is positioned in the full-section deep-hole pre-grouting outer contour line;
the support system includes:
one end of each grouting sleeve valve pipe is positioned on an excavation section, the other end of each grouting sleeve valve pipe extends towards the tunneling direction of the tunnel, and one end of each grouting sleeve valve pipe is distributed in the tunnel excavation contour line;
and the pipe sheds are positioned between the tunnel excavation contour lines and the full-section deep-hole pre-grouting outer contour lines and form a dense-net type pipe shed.
2. The dense-mesh type advanced support system of the underground excavated tunnel according to claim 1, further comprising:
the advanced small guide pipes are located between the tunnel excavation contour lines and the full-section deep-hole pre-grouting outer contour lines and used for reinforcing rock and soil close to the inner side face of the tunnel.
3. The dense-mesh type advanced support system of an underground excavated tunnel according to claim 1,
a plurality of pipe sheds are arranged on the periphery of the arc of the tunnel arch part to form a single-row pipe shed;
in the single-row pipe sheds, the distances from the pipe sheds to the arc of the arch part of the tunnel are the same;
the single-row pipe shed is provided with at least two groups, the distance from the pipe shed to the arc of the tunnel arch in each single-row pipe shed is different, and the pipe sheds in the two adjacent groups of single-row pipe sheds are arranged in a staggered mode.
4. The dense-mesh type advanced support system of an underground excavated tunnel according to claim 1,
the slurry stopping wall is arranged at the starting end of each tunneling section;
preferably, one end of the pipe shed is fixedly connected with the grout stopping wall, and an included angle of 1-3 degrees is formed between the axis of the pipe shed and the central line of the tunnel.
5. The dense-mesh type advanced support system of an underground excavated tunnel according to claim 2,
the steel frames are arranged at intervals in the excavated tunnel along the tunneling direction of the tunnel;
preferably, one end of the advanced small guide pipe is located on an excavation section and takes the steel frame as a fulcrum, and an included angle of 15-25 degrees is formed between the axis of the advanced small guide pipe and the central line of the tunnel.
6. The dense-mesh type advanced support system of an underground excavated tunnel according to claim 1,
a reinforcement cage is arranged in the pipe shed, pipe shed grout overflow holes are formed in the pipe shed, the pipe shed grout overflow holes are uniformly distributed in the pipe shed, small guide pipe grout overflow holes are formed in the advanced small guide pipes, and the small guide pipe grout overflow holes are uniformly distributed in the advanced small guide pipes.
7. The dense-mesh type advanced support system of an underground excavated tunnel according to claim 6,
the steel reinforcement cage is in including tubular steel reinforcement cage skeleton and setting the reinforcing bar on the lateral surface of steel reinforcement cage skeleton, the reinforcing bar is provided with many, all the reinforcing bar in equidistant setting on the lateral surface of steel reinforcement cage skeleton.
8. The dense-mesh type advanced support system of an underground excavated tunnel according to claim 4,
one end of the grouting sleeve valve pipe is located on the grout stopping wall, the grouting sleeve valve pipe is arranged around the center line of the tunnel at intervals, one end of the grouting sleeve valve pipe is fixed, and the other end of the grouting sleeve valve pipe is divergently arranged relative to the center line of the tunnel.
9. A close-mesh type advanced support construction method of an underground excavation tunnel is characterized by comprising the following steps:
constructing a grout stop wall, arranging a full-face grouting sleeve valve pipe in the outline of the excavated section of the tunnel, and grouting in advance to reinforce the stratum so as to stabilize the excavated section;
erecting a steel frame at the excavation section of the tunnel;
arranging a pipe shed;
and an advanced small conduit is arranged in the gap of the pipe shed by taking the steel frame as a fulcrum.
10. The close-meshed advance support construction method of an underground excavation tunnel according to claim 9,
designing a tunnel excavation contour line and a full-section deep hole pre-grouting outer contour line on the excavation section of the tunnel;
arranging the grouting sleeve valve pipes into the tunnel excavation contour lines, and performing full-face grouting reinforcement on the areas in the tunnel excavation contour lines through the grouting sleeve valve pipes;
and arranging the pipe shed in an area between the tunnel excavation contour line and the full-section deep hole pre-grouting outer contour line, and forming a dense-net type pipe shed.
CN202010252994.1A 2020-04-01 2020-04-01 Dense-mesh type advanced support system of underground excavation tunnel and construction method Pending CN111502696A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112031813A (en) * 2020-09-08 2020-12-04 中交一公局第一工程有限公司 Construction method for penetrating through clay loose tunnel collapsed body
CN112127910A (en) * 2020-09-21 2020-12-25 北京市市政工程研究院 Tunnel construction extra-front supporting sheath arch structure
CN112377216A (en) * 2020-11-12 2021-02-19 招商局重庆交通科研设计院有限公司 Small-angle construction method based on pipe shed in drill jumbo tunnel

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112031813A (en) * 2020-09-08 2020-12-04 中交一公局第一工程有限公司 Construction method for penetrating through clay loose tunnel collapsed body
CN112127910A (en) * 2020-09-21 2020-12-25 北京市市政工程研究院 Tunnel construction extra-front supporting sheath arch structure
CN112377216A (en) * 2020-11-12 2021-02-19 招商局重庆交通科研设计院有限公司 Small-angle construction method based on pipe shed in drill jumbo tunnel

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