阅读说明：本技术 一种浅埋隧道支护结构及其施工方法 (Shallow tunnel supporting structure and construction method thereof ) 是由 陈平 李笑 张振宇 隋民锋 伊兴芳 许占良 赵晨生 于 2021-07-28 设计创作，主要内容包括：本发明公开了一种浅埋隧道支护结构及其施工方法,其支护结构包括隧道内的上台阶、中台阶、下台阶,所述上台阶处设置有上台阶支护结构,中台阶处设置有中台阶支护结构,下台阶处设置有下台阶支护结构,所述上台阶支护结构中设置有对其进行固定的楔形锚固组件；其施工方法,包括以下步骤：施工楔形孔；安装拉杆上锚爪、中部锚爪；装入拉杆；施工锚固基础；施工上台阶支护结构；施工中台阶支护结构；施工下台阶支护结构。本发明施工方法简单,便于施工,结构受力明确,楔形锚固可以保证拱部钢架的稳定性,进而保证浅埋隧道施工的安全性,实现了隧道支护结构外部受力,节省了内部空间,在隧道开挖时可以上大型机械进行开挖作业,提高了施工的进度。(The invention discloses a shallow tunnel supporting structure and a construction method thereof, wherein the supporting structure comprises an upper step, a middle step and a lower step in a tunnel, the upper step is provided with an upper step supporting structure, the middle step is provided with a middle step supporting structure, the lower step is provided with a lower step supporting structure, and a wedge-shaped anchoring assembly for fixing the upper step supporting structure is arranged in the upper step supporting structure; the construction method comprises the following steps: constructing a wedge-shaped hole; installing a pull rod upper anchor fluke and a middle anchor fluke; a pull rod is arranged; constructing an anchoring foundation; constructing an upper step supporting structure; constructing a middle step supporting structure; and constructing a lower step supporting structure. The construction method is simple, convenient to construct and clear in structural stress, the stability of the arch steel frame can be guaranteed through wedge-shaped anchoring, the safety of shallow tunnel construction is further guaranteed, the external stress of the tunnel supporting structure is achieved, the internal space is saved, large-scale machinery can be used for excavation operation during tunnel excavation, and the construction progress is improved.)

1. The utility model provides a shallow tunnel supporting construction that buries, includes upper ledge, well step, the lower step in the tunnel, its characterized in that: the upper step is provided with an upper step supporting structure, the middle step is provided with a middle step supporting structure, the lower step is provided with a lower step supporting structure, and the upper step supporting structure is internally provided with a wedge-shaped anchoring assembly for fixing the upper step.

2. The shallow tunnel supporting structure of claim 1, wherein: the wedge-shaped anchoring component comprises a wedge-shaped hole in a soil body, and a pull rod (5) fixed with an upper step steel frame (9) in an upper step supporting structure is arranged in the wedge-shaped hole.

3. The shallow tunnel supporting structure of claim 2, wherein: the top of the soil body forms a foundation pit, and the free end of the pull rod (5) is anchored in an anchoring foundation (1) in the foundation pit.

4. A shallow tunnel supporting construction as claimed in claim 3, wherein: a reinforcing structure for reinforcing is arranged outside the pull rod (5).

5. The shallow tunnel supporting structure of claim 4, wherein: the reinforced structure comprises a pull rod upper anchor fluke (2) arranged on a pull rod (5), wherein the pull rod upper anchor fluke (2) is arranged in the anchoring foundation (1).

6. The shallow tunnel supporting structure of claim 4, wherein: the reinforced structure comprises a middle anchor fluke (4) arranged on the pull rod (5), the middle anchor fluke (4) is positioned in a wedge shape, and micro-expansion cement mortar (3) is filled in the wedge-shaped hole.

7. The shallow tunnel supporting structure of claim 4, wherein: the reinforced structure comprises a pull rod lower anchor claw (4) arranged on a pull rod (5), and the pull rod (5) penetrates through the upper step type steel frame (9) and then is installed in the pull rod lower anchor claw (4), so that the upper step type steel frame (9) is fixed.

8. The shallow tunnel supporting structure of claim 4, wherein: and a fixed anchor pipe (15) for reinforcing the middle support is arranged at the middle support.

9. A construction method of a shallow tunnel supporting structure is characterized by comprising the following steps: the method comprises the following steps:

constructing wedge-shaped hole

Drilling to the end position of the pull rod (5) in the tunnel during design by adopting a variable-diameter drilling machine;

(ii) mounting the upper fluke and the middle fluke of the tie rod

Installing the anchor fluke (2) and the middle anchor fluke (4) on the pull rod (5) to complete the installation of the pull rod (5);

(iii) Loading Pull rod

Putting the pull rod (5) into the drilled wedge-shaped hole, inserting a grouting pipe into the bottom of the wedge-shaped hole, and injecting micro-expansion cement mortar (3) with the strength of more than M30 to fill the gap in the hole for hole sealing and fixing;

(iv) construction anchoring Foundation

Excavating a foundation pit of the anchoring foundation (1), installing reinforcing steel bars of the anchoring foundation (1), and pouring concrete of the anchoring foundation part;

(v) construction upper step supporting structure

After the upper step supporting structure is constructed and installed on the upper step steel frame (9), the pull rod (5) penetrates through a preformed hole in the upper step steel frame (9), a pull rod lower anchor fluke (6) is installed, and construction is continued until the construction of the upper step supporting structure is completed;

(vi) step supporting construction in construction

After the middle-step supporting structure is constructed on the middle-step steel frame (13), drilling holes obliquely downwards, removing soil and stone impurities in the holes by adopting high-pressure air, inserting the holes into the fixed anchor pipes (15), then injecting cement mortar, welding and fixing the outer leakage parts of the fixed anchor pipes (15) and the middle-step steel frame (13), and continuing construction until the construction of the middle-step supporting structure is completed;

(vii) construction lower step supporting structure

And continuing constructing the lower step supporting structure until the construction is finished.

10. The construction method of a shallow tunnel supporting structure according to claim 8, wherein: and (vi) the inclined angle of the inclined downward drilling hole is 45 degrees.

Technical Field

The invention belongs to the technical field of structural design of shallow-buried tunnels and underground engineering, and particularly relates to a shallow-buried tunnel supporting structure and a construction method thereof.

Background

With the development of national infrastructure construction of railways, roads, subways and the like, underground projects such as tunnels often suffer from the influence of terrain conditions and surrounding buildings and have to be designed and constructed by a shallow-buried underground excavation method. The traditional internal support supporting structure has a plurality of problems: firstly, the steel frame for fixing the top of the arch is unstable, the steel frame is easy to drop, the arch is collapsed, and potential safety hazards exist; secondly, the temporary inner supports divide the tunnel into smaller operation spaces, large machinery is not used, manual excavation is mostly adopted, the efficiency is low, and the progress is slow; thirdly, when dismantling the interim interior support, tunnel supporting construction will experience a structure atress conversion, and the inboard bearing capacity disappears suddenly, and outer layer structure warp greatly, has the safe risk that the tunnel collapses.

The shallow tunnel supporting structure and the construction method thereof can effectively solve the problems.

Disclosure of Invention

The invention is provided for solving the problems in the prior art, and aims to provide a shallow tunnel supporting structure and a construction method thereof.

The technical scheme of the invention is as follows: the utility model provides a shallow tunnel supporting construction, includes upper ledge, well step, lower step in the tunnel, upper ledge department is provided with upper ledge supporting construction, and well step department is provided with well step supporting construction, and lower step department is provided with lower step supporting construction, be provided with the wedge anchor subassembly of fixing it in the upper ledge supporting construction.

Furthermore, the wedge-shaped anchoring component comprises a wedge-shaped hole in the soil body, and a pull rod fixed with an upper step steel frame in the upper step supporting structure is arranged in the wedge-shaped hole.

Furthermore, a foundation pit is formed at the top of the soil body, and the free end of the pull rod is anchored in an anchoring foundation in the foundation pit.

Furthermore, a reinforcing structure for reinforcing is arranged outside the pull rod.

Furthermore, the reinforcing structure comprises a pull rod upper fluke arranged on the pull rod, and the pull rod upper fluke is arranged in the anchoring foundation.

Furthermore, the reinforcing structure comprises a middle anchor claw arranged on the pull rod, the middle anchor claw is positioned in a wedge shape, and the wedge-shaped hole is filled with micro-expansion cement mortar.

Furthermore, the reinforced structure comprises a pull rod lower anchor claw arranged on the pull rod, and the pull rod penetrates through the upper step steel frame and then is installed into the pull rod lower anchor claw, so that the upper step steel frame is fixed.

Furthermore, a fixed anchor pipe for reinforcing the middle support is arranged at the middle support.

A construction method of a shallow tunnel supporting structure comprises the following steps:

i.e. construction wedge-shaped hole

Drilling to the end position of the pull rod in the tunnel during design by adopting a variable-diameter drilling machine;

ii, mounting the upper anchor fluke and the middle anchor fluke of the pull rod

Installing the upper anchor fluke and the middle anchor fluke of the pull rod on the pull rod to complete the installation of the pull rod;

iii, load the tie rod

Placing the pull rod into the drilled wedge-shaped hole, injecting micro-expansion cement mortar with the strength of more than M30 into the hole through a grouting pipe to fill the gap in the hole, and sealing and fixing the hole;

iv. construction anchoring foundation

Excavating a foundation pit of the anchoring foundation, installing reinforcing steel bars of the anchoring foundation, and pouring concrete of the anchoring foundation part;

v. construction upper step supporting structure

After the upper step supporting structure is constructed and installed on the upper step steel frame, the pull rod penetrates through a preformed hole in the upper step steel frame, a pull rod lower anchor fluke is installed, and construction is continued until the construction of the upper step supporting structure is completed;

step supporting construction in vi

After the middle-step supporting structure is constructed on the middle-step steel frame, drilling holes obliquely downwards, removing soil and stone impurities in the holes by adopting high-pressure air, inserting the fixed anchor pipes, then injecting cement mortar, welding and fixing the outer leakage parts of the fixed anchor pipes and the middle-step steel frame, and continuing construction until the construction of the middle-step supporting structure is completed;

vii construction lower step supporting construction

And continuing constructing the lower step supporting structure until the construction is finished.

Further, step vi is carried out with the angle of inclination of the drill hole inclined downward being 45 °.

The construction method is simple, convenient to construct, clear in structural stress, capable of guaranteeing the stability of the arch steel frame through wedge-shaped anchoring, further guaranteeing the safety of shallow tunnel construction, achieving the external stress of the tunnel supporting structure, saving the internal space, capable of being excavated by large-scale machinery during tunnel excavation, improving the construction progress, safe and efficient, and wide in application and popularization prospect.

The method solves the problems of potential safety hazard of unstable fixation of the arch crown section steel frame, temporary internal support safety risk removal and small construction space, low efficiency and slow progress caused by an internal support structure in the shallow tunnel construction process, and can improve construction safety guarantee and mechanization rate.

Drawings

Figure 1 is a schematic view of the support structure of the present invention;

FIG. 2 is a schematic structural view of the wedge anchor assembly of the present invention;

figure 3 is a plan view of a fluke according to the invention;

figure 4 shows a fluke according to the invention

Wherein:

1 anchoring foundation 2 pull rod upper fluke

3 micro-expansion cement mortar 4 middle anchor fluke

5 draw bar 6 draw bar lower anchor claw

7 upper step one layer sprayed concrete 8 upper step reinforcing mesh

9 upper step section steel frame 10 upper step two-layer sprayed concrete

11 middle step one-layer sprayed concrete 12 middle step reinforcing mesh

13 middle step type steel frame 14 middle step two-layer sprayed concrete

15 fixed anchor pipe 16 lower step one-layer sprayed concrete

17 lower step reinforcing mesh 18 lower step steel frame

19 lower step two-layer sprayed concrete 20 anchor fluke screw thread

21 fluke fingers.

Detailed Description

The present invention is described in detail below with reference to the accompanying drawings and examples:

as shown in fig. 1 to 4, a shallow tunnel supporting structure comprises an upper step, a middle step and a lower step in a tunnel, wherein the upper step is provided with an upper step supporting structure, the middle step is provided with a middle step supporting structure, the lower step is provided with a lower step supporting structure, and a wedge-shaped anchoring assembly for fixing the upper step supporting structure is arranged in the upper step supporting structure.

The wedge-shaped anchoring component comprises a wedge-shaped hole in a soil body, and a pull rod 5 fixed with an upper step steel frame 9 in an upper step supporting structure is arranged in the wedge-shaped hole.

The top of the soil body forms a foundation pit, and the free end of the pull rod 5 is anchored in an anchoring foundation 1 in the foundation pit.

A reinforcing structure for reinforcing is arranged outside the pull rod 5.

The reinforcing structure comprises a pull rod upper anchor fluke 2 arranged on a pull rod 5, and the pull rod upper anchor fluke 2 is arranged in the anchoring foundation 1.

The reinforcing structure comprises a middle anchor fluke 4 arranged on a pull rod 5, the middle anchor fluke 4 is positioned in a wedge shape, and micro-expansion cement mortar 3 is filled in the wedge-shaped hole.

The reinforced structure comprises a pull rod lower anchor fluke 4 arranged on a pull rod 5, and the pull rod 5 penetrates through the upper step type steel frame 9 and then is installed into the pull rod lower anchor fluke 4, so that the upper step type steel frame 9 is fixed.

And a fixed anchor pipe 15 for reinforcing the middle support is arranged at the middle support.

The pull rod upper fluke 2, the middle fluke 4 and the pull rod lower fluke 6 comprise fluke screw threads 20 fixed with the pull rod 5, fluke fingers 21 are arranged outside the fluke screw threads 20, and the fluke fingers 21 are in a divergence shape.

Furthermore, the fluke fingers 21 in the upper fluke 2 and the middle fluke 4 of the draw rod are inclined downwards and the fluke fingers 21 in the bottom fluke 6 are inclined upwards.

The wedge-shaped anchoring assembly is provided with a wedge-shaped anchoring structure with a large upper drilling hole diameter and a small lower drilling hole diameter, when the lower part of the pull rod 5 bears downward pulling force, the anchoring foundation 1 of the wedge-shaped anchoring assembly provides a part of supporting force, the micro-expansion cement mortar 3 provides friction force with surrounding rock and lateral extrusion force to the surrounding rock, and the downward pulling force of the pull rod 5 is shared by acting forces of the supporting force, the friction force and the extrusion force.

After the construction wedge anchor subassembly, when installing upper step shaped steel steelframe 9, reserve the hole on upper step shaped steel steelframe 9 for penetrate pull rod 5, penetrate upper step shaped steel steelframe 9 preformed hole with pull rod 5 lower part end and tighten pull rod anchor fluke 6, and weld pull rod 5 lower part end and upper step shaped steel steelframe 9, make pull rod 5 and upper step shaped steel steelframe 9 firm in connection, thereby solve the fixed unstable problem of upper step shaped steel steelframe 9.

Realized tunnel superstructure external fixation through pull rod 5, realized through anchor pipe 15 that the tunnel mid-step supporting structure is fixed, replaced the shallow interim bearing structure who buries tunnel supporting structure of tradition, make whole tunnel supporting structure's fixed and atress all set up outside the headroom in the tunnel, saved the inside space in tunnel, can realize large-scale mechanized excavation country rock construction.

Meanwhile, a temporary inner supporting structure is omitted, mechanical conversion of a supporting structure for dismantling the inner support is avoided, and safety and reliability of the tunnel supporting structure are improved.

A construction method of a shallow tunnel supporting structure comprises the following steps:

i.e. construction wedge-shaped hole

Drilling to the end position of the pull rod 5 in the tunnel during design by adopting a variable-diameter drilling machine;

ii, mounting the upper anchor fluke and the middle anchor fluke of the pull rod

Mounting the anchor fluke 2 and the middle anchor fluke 4 on the pull rod 5 to complete the mounting of the pull rod 5;

iii, load the tie rod

Placing the pull rod 5 into the drilled wedge-shaped hole, injecting micro-expansion cement mortar 3 with the strength of more than M30 into the wedge-shaped hole to fill the gap in the hole, and sealing and fixing the hole;

iv. construction anchoring foundation

Excavating a foundation pit of the anchoring foundation 1, installing reinforcing steel bars of the anchoring foundation 1, and pouring concrete of the anchoring foundation part;

v. construction upper step supporting structure

After the upper step supporting structure is constructed and installed on the upper step steel frame 9, the pull rod 5 penetrates through a preformed hole in the upper step steel frame 9, a pull rod lower anchor claw 6 is installed, and construction is continued until the construction of the upper step supporting structure is completed;

step supporting construction in vi

After the middle step supporting structure is constructed to the middle step steel frame 13, drilling holes obliquely downwards, removing soil and stone impurities in the holes by adopting high-pressure air, inserting the holes into the fixed anchor pipes 15, then injecting cement mortar, and continuing construction until the construction of the middle step supporting structure is completed;

vii construction lower step supporting construction

And continuing constructing the lower step supporting structure until the construction is finished.

And in the step vi, the inclined angle of the inclined downward drilling hole is 45 degrees.

In the step i, the drill bit of the drilling machine is directly small, the diameter of the drill rod is gradually enlarged, and after drilling, soil and stone impurities in the hole are removed, so that the drilling work of the wedge-shaped hole is completed.

In the step iii, the micro-expansion cement mortar 3 plays a role in tightly combining the wedge-shaped anchoring structure with the surrounding rock (soil body) and simultaneously plays a role in hole sealing, so that ground precipitation can be prevented from leaking to the tunnel structure along the drilled hole.

In step iv, the concrete of the anchoring base 1 part is concrete above C30.

Step v, constructing the upper step supporting structure, which comprises the following specific steps:

excavating the tunnel to reach the corresponding mileage, excavating the surrounding rock (soil mass) of the upper step in the tunnel, and quickly constructing a layer of sprayed concrete 7 on the upper step; after the strength of the sprayed concrete 7 on the upper step layer reaches the designed strength, constructing an upper step reinforcing steel bar net piece 8, drilling holes on the sprayed concrete layer by using a percussion drill, wherein the depth of the holes is 0.4 m, the distance between the holes is 1 m, an anchoring agent is placed in the holes, 0.5 m long short reinforcing steel bars are inserted into the holes, welding the upper step reinforcing steel bar net piece 8 on the reinforcing steel bars, and ensuring that the upper step reinforcing steel bar net 8 is closely attached to the sprayed concrete 7 on the upper step layer.

Then, an upper step section steel frame 9 is installed, a hole is reserved in the upper step section steel frame 9 and used for penetrating a pull rod 5, the lower end of the pull rod 5 penetrates into a reserved hole of the upper step section steel frame 9 and is fastened with a pull rod lower anchor claw 6, the lower end of the pull rod 5 is welded with the upper step section steel frame 9, the pull rod 5 is connected with the upper step section steel frame 9, and the pull rod 5 bears the self weight of the upper step section steel frame 9 and the pressure of surrounding rocks (soil).

And finally, constructing an upper step and spraying concrete 10 on the second layer to completely cover the upper step steel bar mesh 8, the upper step steel frame 9 and the end of the pull rod 5.

Vi step supporting construction in the construction concrete step as follows:

after the strength of the second sprayed concrete layer 10 of the upper step reaches the design strength, the surrounding rock (soil body) of the middle step is continuously excavated, the sprayed concrete 11 is sprayed on the first sprayed concrete layer of the middle step in construction, the reinforcing mesh 12 of the middle step is constructed after the strength of the sprayed concrete 11 of the middle step reaches the design strength, 1-2 meshes of the upper reinforcing mesh 8 and the reinforcing mesh 12 of the middle step need to be lapped, holes are drilled in the first sprayed concrete layer 11 of the middle step by using a percussion drill, an anchoring agent is placed in the holes, short reinforcing steel bars of 0.5 meter long are inserted, the reinforcing mesh 12 of the middle step is welded on the short reinforcing steel bars, and the reinforcing mesh 12 of the middle step is guaranteed to be closely attached to the sprayed concrete 11 of the first sprayed concrete layer of the middle step.

Then, the middle step steel frame 13 is installed, bolt holes are reserved in the connecting steel plates of the middle step steel frame 13 and the upper step steel frame 9, and the middle step steel frame and the upper step steel frame are connected through bolts and nuts.

And then, drilling holes at an angle of 45 degrees downwards in an inclined mode, removing soil and stone impurities in the holes by adopting high-pressure air, inserting the fixed anchor pipes 15, injecting micro-expansion cement mortar, increasing the rigidity of the fixed anchor pipes 15 and the friction force with surrounding rocks, firmly welding the fixed anchor pipes 15 and the middle-step steel frame 13, ensuring that the length of welding seams is not less than 10 cm, ensuring that the welding seams are full, and playing a role in supporting and fixing the middle-step steel frame 13.

And finally, constructing a second layer of sprayed concrete 14 to completely cover the middle-step steel bar mesh 12, the middle-step steel frame 13 and the fixed anchor pipe 15.

It should be noted that the upper-step one-layer sprayed concrete 7 and the middle-step one-layer sprayed concrete 11, the upper-step steel mesh 8 and the middle-step steel mesh 12, the upper-step steel frame 9 and the lower-step steel frame 13, and the upper-step two-layer sprayed concrete 10 and the middle-step two-layer sprayed concrete 14 are all in lap joint, so that the upper-layer and middle-layer supporting structures are integrally stressed.

The specific process of constructing the lower step supporting structure in the step vii is as follows:

and (3) when the strength of the second sprayed concrete layer 14 of the middle step reaches the designed strength, continuously excavating the surrounding rock of the lower step, constructing the first sprayed concrete layer 16 of the lower step, constructing the reinforcing mesh 17 of the lower step after the strength of the first sprayed concrete layer 16 of the lower step reaches the designed strength, overlapping 1-2 meshes of the reinforcing mesh 12 of the middle step and the reinforcing mesh 17 of the lower step, drilling holes in the first sprayed concrete layer of the middle step by using a percussion drill, putting anchoring agents into the holes, inserting short reinforcing steel bars with the length of 0.5 meter, welding the reinforcing mesh 17 of the lower step on the short reinforcing steel bars, and ensuring that the reinforcing mesh 17 of the lower step is closely attached to the first sprayed concrete layer 16 of the lower step.

And then, installing a lower step steel frame 18, connecting the middle step steel frame 13 and the lower step steel frame 18 by using bolts and nuts through reserved bolt holes on a connecting steel plate, and constructing a lower step two-layer sprayed concrete 19 to completely cover the lower step steel mesh 17 and the lower step steel frame 18.

And at this moment, the supporting structures of the upper step, the middle step and the lower step are connected and sealed to form a ring, and the whole tunnel supporting structure is completely finished. The upper step, the middle step and the lower step are connected through the one-layer sprayed concrete, the steel mesh, the profile steel frame and the two-layer sprayed concrete in a lap joint mode, and therefore the supporting structure of the upper step, the middle step and the lower step is integrally stressed.

The construction method is simple, convenient to construct, clear in structural stress, capable of guaranteeing the stability of the arch steel frame through wedge-shaped anchoring, further guaranteeing the safety of shallow tunnel construction, achieving the external stress of the tunnel supporting structure, saving the internal space, capable of being excavated by large-scale machinery during tunnel excavation, improving the construction progress, safe and efficient, and wide in application and popularization prospect.

The method solves the problems of potential safety hazard of unstable fixation of the arch crown section steel frame, temporary internal support safety risk removal and small construction space, low efficiency and slow progress caused by an internal support structure in the shallow tunnel construction process, and can improve construction safety guarantee and mechanization rate.