An internal pipe shed support device and a method for directly constructing an internal pipe shed

Abstract

The present invention discloses an internal pipe shed support device and a method for directly constructing an internal pipe shed in a tunnel. By using the last erected steel arch near the heading face as a simple positioning frame, an internal pipe shed is driven into the surrounding rock in front of the heading face. After the pipe shed grouting is completed, an internal pipe shed bracket structure with reverse elongation is set at the end of the pipe shed, which can significantly improve the bearing capacity of the internal pipe shed in the tunnel to resist the vertical load of the arch surrounding rock during the excavation and suspension stage, effectively prevent the problem of the overall failure of the internal pipe shed in the tunnel caused by the settlement and deformation at the end of the pipe shed, and the entire construction process has simple procedures and strong operability. Moreover, the construction of the internal pipe shed in the tunnel completely follows the heading face, does not require special auxiliary operation space, has extremely high structural flexibility, can effectively cope with sudden construction situations such as collapse, roof fall or sudden exposure of a soft and broken zone at the heading face, has a wide application range and strong practicability.

Description

Technical Field

[0001] The present invention relates to an embedded pipe shed support device and a method for directly constructing an in - tunnel pipe shed, belonging to the technical field of tunnel construction. Background Art

[0002] During tunnel construction, it may encounter soft and fractured surrounding rock zones, or accidents such as face collapses and roof falls. At this time, the support length of the advanced small pipes or advanced bolts is not sufficient to effectively penetrate the potential fracture angle, and thus it is impossible to ensure the stability of the surrounding rock in the arch part during the excavation and suspension stage. To ensure construction safety, advanced pipe sheds are generally selected as the advanced support measures for crossing the above - mentioned poor geological zones. Conventional in - tunnel pipe shed construction requires the setting up of a pipe shed working chamber, and the construction of the pipe shed working chamber involves the excavation of the initial support structure of the tunnel, which requires a certain structural space. Considering that the exposure of soft and fractured surrounding rock, face collapse or roof fall accidents at the tunnel face are highly sudden, if the initial support structure is demolished backward from the tunnel face to construct the pipe shed working chamber at this time, it will result in scrapped projects, while expanding and excavating the pipe shed working chamber forward into the soft and fractured zone or the collapsed body in front of the tunnel face has extremely high construction risks, and thus it is basically impossible to construct the pipe shed working chamber under the above - mentioned sudden situations during actual construction. At the same time, there are certain drawbacks in terms of construction cost, construction period and construction risk in building the pipe shed working chamber, resulting in less use of the pipe shed working chamber to assist in - tunnel pipe shed construction during the actual tunnel construction process.

[0003] Currently, for the construction of in - tunnel pipe sheds, some studies have been exploring how to simplify or cancel the pipe shed working chamber, but most of the research measures do not consider in detail the interference problem of the face construction space or the stress characteristics of the in - tunnel pipe shed during construction, and thus it is difficult to truly meet the relevant technical requirements of the in - tunnel pipe shed for tunnel construction. In view of the above situation, it is of great practical significance to study an embedded pipe shed support device and a method for directly constructing an in - tunnel pipe shed. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide an embedded pipe shed support device and a method for directly constructing an in - tunnel pipe shed, which can overcome the deficiencies of the prior art.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] An embedded pipe shed support device, which includes a simple positioning frame. The simple positioning frame is the last erected steel arch frame near the tunnel face; a number of pipe shed positioning holes are provided on the simple positioning frame, and an in - tunnel pipe shed is arranged in the pipe shed positioning holes. The in - tunnel pipe shed is inclined upward as a whole and penetrates into the surrounding rock in front of the tunnel face, and its end is provided with an embedded pipe shed bracket structure with reverse elongation.

[0007] The aforementioned built-in pipe-roof bracket structure includes a rotatable pipe-connecting device, and an arc-shaped steel support is provided at the bottom of the rotatable pipe-connecting device.

[0008] The aforementioned rotatable pipe-connecting device includes a base, on which an inclined wedge-shaped cutting groove is provided. An installation groove is provided on the inclined downward side close to the wedge-shaped cutting groove, and an elastic connecting piece is provided on the other side. A pipe-extension sleeve assembly is provided in the wedge-shaped cutting groove. One end of the pipe-extension sleeve assembly is hinged to a hinge shaft arranged in the installation groove, and the other end is connected to the elastic connecting piece. Moreover, the pipe-extension sleeve assembly fits with the wedge-shaped cutting groove under the restoring force of the elastic connecting piece.

[0009] The aforementioned arc-shaped steel support is a spliced temporary arch protection structure arranged along the tunnel contour. The spliced temporary arch protection structure is spliced by I20a-type steel I-beams. A shotcrete connection structure is arranged below the steel I-beams to fixedly connect it with the existing primary support of the tunnel as a whole.

[0010] A method for directly constructing a pipe roof in a tunnel includes the following steps:

[0011] S1. According to the instability condition of the tunnel face, use tunnel muck or pervious stones to backfill the tunnel face in a reverse pressure manner and form a construction platform;

[0012] S2. Take the last erected steel arch near the tunnel face as a simple positioning frame, and process a number of pipe-roof positioning holes along the tunnel arch contour at the web position of the simple positioning frame;

[0013] S3. Incline upward and drive the in-tunnel pipe roof into the surrounding rock in front of the tunnel face from the pipe-roof positioning holes;

[0014] S4. After the in-tunnel pipe roof is driven, use grouting equipment to carry out high-pressure grouting construction for the in-tunnel pipe roof;

[0015] S5. Carry out reverse extension of the pipe roof along the rear of the tunnel face at the end of the in-tunnel pipe roof to form a built-in pipe-roof bracket structure with reliable force-bearing;

[0016] S6. Carry out tunnel face excavation and support construction in sequence under the protection of the in-tunnel pipe roof;

[0017] S7: After the excavated tunnel face effectively passes through the collapsed body or the soft and broken zone at the end of the pipe roof, and there are no less than 2 - 3 primary support steel I-beams under the in-tunnel pipe roof, carry out the demolition construction of the built-in pipe-roof bracket structure;

[0018] S8. After all the built-in pipe-roof bracket structures are demolished, construct the primary support shotcrete in this area so that the in-tunnel pipe roof is completely covered in the primary support.

[0019] In the aforementioned step S1, if the surrounding rock of the tunnel face deteriorates sharply but has not yet developed into a tunnel face collapse accident, it is only necessary to use tunnel muck or permeable stone materials to backfill the tunnel face in a counter-pressure manner to form a construction platform;

[0020] If a large-scale collapse or roof fall occurs at the tunnel face, first use tunnel muck or permeable stone materials to backfill the tunnel face in a counter-pressure manner to form a construction platform; then spray concrete or grout the collapsed body to ensure the relative stability of the collapsed body;

[0021] The above construction shall not block the groundwater drainage channel. When necessary, inclined drainage holes shall be drilled to drain the groundwater.

[0022] In the aforementioned step S2, use the last set of steel arch frames erected near the tunnel face as a simple positioning frame and perform simple treatment:

[0023] 1) Add φ60 or φ76 foot-locking anchor pipes at the arch feet of the steel arch frame, with the length controlled within 4.5 - 6.0 m;

[0024] 2) Use electric welding cutting to cut the pipe shed positioning holes at the web position of the simple positioning frame. The positions and quantities of the pipe shed positioning holes are determined according to the construction plan. The pipe shed positioning holes are set within a 120° range of the tunnel arch, with the number of settings being 27 - 35, and the adjacent pipe shed positioning holes are set at equal or unequal distances.

[0025] In the aforementioned step S3, with the help of the pipe shed positioning holes on the simple positioning frame, use a down-the-hole drill or other drilling equipment to carry out the drilling construction of the portal pipe shed. For severely caving sections of the surrounding rock, the pipe follower drilling process should be adopted; for the in-tunnel pipe shed, use φ89 or φ108 grouting steel pipes, and the length of the steel pipes should be controlled within the range of 8 - 15 m, and the drilling angle of the pipe shed should be controlled within the range of 5 - 10°.

[0026] In the aforementioned step S4, after the in-tunnel pipe shed is installed, use grouting equipment to carry out high-pressure grouting construction. After the grouting is completed, fill the steel pipe with M20 cement mortar, and add a steel cage made of 4 φ20 steel bars in the pipe shed to improve the stiffness of the pipe shed body.

[0027] In the aforementioned step S5, the specific construction steps of the pipe shed bracket structure are as follows:

[0028] a. Use a hollow extension sleeve with a rotatable connecting device to sleeve the end of the in-tunnel pipe shed, and use a limiting mechanism to tightly clamp and lock the in-tunnel pipe shed to achieve the fixed connection between the hollow extension sleeve and the in-tunnel pipe shed; at this time, the elastic connection rope suspends the base through the hollow extension sleeve positioned with the in-tunnel pipe shed to prevent the base from rotating and swinging up and down during the suspended stage below.

[0029] b. Each pipe shed in the tunnel corresponds to a set of rotatable pipe connecting devices. After all the rotatable pipe connecting devices are installed, an arc-shaped steel support is erected at the front and rear ends of the base of the rotatable pipe connecting device to support the rotatable pipe connecting device, and the arc-shaped steel support is fixedly connected to the existing primary support of the tunnel as a whole through a shotcrete connection structure. Thus, the installation construction of the built-in pipe shed bracket structure at the end of the pipe shed in the tunnel is completed.

[0030] In the aforementioned step S6, under the protection of the pipe shed in the tunnel, the face excavation and support construction are carried out. The erection construction of the primary support steel frame and the shotcrete construction of the primary support are carried out under the pipe shed in the tunnel in the way of "excavating one frame and supporting one frame".

[0031] Compared with the prior art, a built-in pipe shed support device and a direct construction method of the pipe shed in the tunnel disclosed by the present invention utilize the last erected steel arch near the face as a simple positioning frame, drive the pipe shed in the tunnel into the surrounding rock in front of the face. After the pipe shed grouting is completed, a built-in pipe shed bracket structure with reverse elongation is set at the end of the pipe shed, which can significantly improve the bearing capacity of the pipe shed in the tunnel to resist the vertical load of the surrounding rock in the arch part during the excavation suspension stage, effectively prevent the problem that the overall failure of the pipe shed in the tunnel is caused by the settlement and deformation at the end of the pipe shed, and is applicable to the technical field of tunnel advanced support construction.

[0032] The beneficial effects of the present invention are as follows:

[0033] (1) The present invention directly utilizes the last erected steel arch near the face as a simple positioning frame, drives the pipe shed in the tunnel into the surrounding rock in front of the face, then reversely elongates the pipe shed in the tunnel through the rotatable pipe connecting device, and further constructs a built-in pipe shed bracket mechanism with reliable force at the elongation part. The whole construction process has simple procedures and strong operability; moreover, the construction of the pipe shed in the tunnel completely follows the face, does not require a special auxiliary operation space, has extremely high structural flexibility, can effectively cope with sudden construction situations such as cave-ins, roof falls or sudden exposure of soft and broken zones at the face, has a wide application range and strong practicability;

[0034] (2) The present invention adopts the pipe shed reverse elongation method and designs a set of built-in pipe shed bracket structures constructed backwards from the face. Compared with the conventional pipe shed working chamber, the built-in pipe shed bracket structure neither needs to demolish the already constructed primary support structure nor needs to forcibly expand the face against risks, which can effectively avoid the adverse effects of the pipe shed working chamber excavation construction in many aspects such as construction cost, construction period and construction risk, and has good economic benefits and engineering benefits;

[0035] (3) The present invention forms an internal pipe shed bracket structure that fits closely with the surface of the initial support through the cooperation of the rotatable connecting pipe device and the arc-shaped steel support. Compared with the existing in-tunnel pipe shed constructed directly, the internal pipe shed bracket structure can effectively support the end of the pipe shed, ensuring the load-bearing capacity of the in-tunnel pipe shed to resist the vertical load of the surrounding rock in the arch part. Moreover, since the overall internal pipe shed bracket structure is closely attached to the initial support, the space occupied by the structure is small, and it basically does not affect the construction of other processes in the tunnel. The structure has reliable functions and extremely little construction interference.

[0036] (4) The rotatable connecting pipe device described in the present invention can meet the elongation conditions of in-tunnel pipe sheds with different elevation angles through its mechanized angle adjustment structure. Moreover, its structural design fully considers the relatively harsh construction environment at the tunnel face position. The mechanical structure is simple and durable, not easily damaged, and has a high reuse rate.

[0037] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, they will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. Brief Description of the Drawings

[0038] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the drawings, where:

[0039] Figure 1 is the longitudinal sectional structure schematic diagram of the present invention.

[0040] Figure 2 is the structural schematic of the rotatable connecting pipe device Figure 1 .

[0041] Figure 3 is the structural schematic of the rotatable connecting pipe device Figure 2 .

[0042] Figure 4 is the connection structure diagram of the hollow extension sleeve, the limiting mechanism, and the in-tunnel pipe shed.

[0043] Figure 5 is the construction process of the present invention Figure 1 .

[0044] Figure 6 is the construction process of the present invention Figure 2 .

[0045] Figure 7 is the construction process of the present invention Figure 3 .

[0046] Figure 8Construction process of the present invention Figure 4 。

[0047] Figure 9 Construction process of the present invention Figure 5 。

[0048] Figure 10 It is an elevation structure diagram of a simple positioning frame.

[0049] Figure 11 It is an installation schematic diagram of a rotatable pipe connecting device and an arc-shaped steel support. Specific embodiments

[0050] Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail. It should be understood that the preferred embodiments are only for illustrating the present invention, rather than for limiting the protection scope of the present invention.

[0051] As Figures 1-11 shown, an in-built pipe shed support device includes a simple positioning frame 1, and the simple positioning frame 1 is the last erected steel arch near the heading face; a number of pipe shed positioning holes 101 are provided on the simple positioning frame 1, and an in-hole pipe shed 2 is provided in the pipe shed positioning holes 101. The in-hole pipe shed 2 is inclined upward as a whole and penetrates into the surrounding rock in front of the heading face, and an in-built pipe shed bracket structure 3 with reverse elongation is provided at its end.

[0052] The in-built pipe shed bracket structure 3 includes a rotatable pipe connecting device, and an arc-shaped steel support is provided at the bottom of the rotatable pipe connecting device.

[0053] The rotatable pipe connecting device includes a base 301. An inclined wedge-shaped cutting groove 302 is provided on the base 301. An installation groove 303 is provided on the side close to the downward slope of the wedge-shaped cutting groove 302, and an elastic connecting piece 304 is provided on the other side. A pipe extension sleeve assembly 305 is provided in the wedge-shaped cutting groove 302. One end of the pipe extension sleeve assembly 305 is hinged to a hinge shaft provided in the installation groove 303, and the other end is connected to the elastic connecting piece 304. And the pipe extension sleeve assembly 305 fits with the wedge-shaped cutting groove 302 under the restoring force of the elastic connecting piece 304.

[0054] The base 301 is a rectangular base.

[0055] The extension casing assembly 305 includes a solid articulated rod 3051. One end of the solid articulated rod 3051 is articulated to the installation groove 303 through a hinge shaft, and the other end is provided with a hollow extension casing 3052 adapted to the in-hole pipe shed 2. A limiting mechanism 3053 is arranged on the outer side of the hollow extension casing 3052; the end of the in-hole pipe shed 2 is sleeved in the hollow extension casing 3052 and is tightly limited by the limiting mechanism 3053. Specifically, the hollow extension casing 3052 is rigidly connected to the solid articulated rod 3051, and the pipe diameter of the hollow extension casing 3052 is set to φ120mm; the limiting mechanism 3053 can be a telescopic limiting screw, which is arranged on both sides of the hollow extension casing 3052, making the operation more convenient.

[0056] The elastic connecting piece 304 includes an elastic connecting rope 3041. One end of the elastic connecting rope 3041 is fixedly connected to the base 301, and the other end is screwed with a connecting end cap 3042; a wire passing hole is opened on the solid articulated rod 3051 of the extension casing assembly 305, and the elastic connecting rope 3041 passes through the wire passing hole of the extension casing assembly 305 and is connected and limited by the connecting end cap 3042.

[0057] The length of the elastic connecting rope 3041 is set according to the rotation angle of the extension casing assembly 305, and its length can make the rotation angle of the extension casing assembly within the range of 5-15°.

[0058] The slope of the ramp of the wedge-shaped cutting groove 302 is set to 5°.

[0059] The driving angle of the in-hole pipe shed 2 is 5-10°.

[0060] The arc-shaped steel support is a spliced temporary arch protection structure arranged along the tunnel contour. The spliced temporary arch protection structure is spliced by I20a type steel I-beams. A shotcrete connection structure 307 is arranged below the steel I-beams to fixedly connect it with the existing primary support of the tunnel into a whole, ensuring the longitudinal stability of the temporary arch and preventing tipping accidents.

[0061] A method for directly constructing an in-hole pipe shed includes the following steps:

[0062] S1. According to the instability condition of the tunnel face, use tunnel muck or permeable stone materials to backfill the face in reverse and form a construction platform 4;

[0063] S2. Take the last erected steel arch near the tunnel face as a simple positioning frame 1, and process a number of pipe shed positioning holes 101 along the tunnel arch contour at the web position of the simple positioning frame 1;

[0064] S3. Incline upward and drive the in-hole pipe shed 2 from the pipe shed positioning hole 101 along the direction of the surrounding rock in front of the tunnel face;

[0065] S4. After the installation of the in - tunnel pipe shed 2 is completed, use grouting equipment to carry out high - pressure grouting construction for the in - tunnel pipe shed 2.

[0066] S5. Along the rear of the heading face at the end of the in - tunnel pipe shed 2, extend the pipe shed in the reverse direction to form a reliable - force - bearing built - in pipe shed bracket structure 3.

[0067] S6. Under the protection of the in - tunnel pipe shed 2, carry out the heading face excavation and support construction in sequence.

[0068] S7: After the excavation heading face effectively passes through the collapsed body or the soft and broken zone at the end of the pipe shed, and there are no less than 2 - 3 primary support I - beams 5 under the in - tunnel pipe shed 2, carry out the demolition construction of the built - in pipe shed bracket structure 3.

[0069] S8. After all the built - in pipe shed bracket structures 3 are demolished, construct the shotcrete for the primary support in this area so that the in - tunnel pipe shed 2 is completely covered by the primary support.

[0070] In step S1, if the surrounding rock of the heading face deteriorates sharply but has not developed into a heading face collapse accident, only need to use tunnel muck or permeable stone materials to backfill the heading face in a reverse pressure manner to form a construction platform 4. In the case of water - rich surrounding rock, inclined upward drainage holes can be drilled in front of the heading face to drain groundwater.

[0071] If a large - scale collapse or roof fall occurs at the heading face, first use tunnel muck or permeable stone materials to backfill the heading face in a reverse pressure manner to form a construction platform 4; then spray - concrete reinforce or grout - reinforce the collapsed body to ensure the relative stability of the collapsed body. The above construction shall not block the groundwater drainage channel. When necessary, inclined upward drainage holes should be drilled to drain groundwater.

[0072] In step S2, use the last erected steel arch frame near the heading face as a simple positioning frame 1 and carry out simple treatment:

[0073] 1) Add φ60 or φ76 foot - locking anchor pipes 6 at the arch feet of the steel arch frame, with the length controlled within 4.5 - 6.0 m.

[0074] 2) Use the electric welding and cutting method to cut the pipe shed positioning holes 101 at the web position of the simple positioning frame 1. The positions and quantities of the pipe shed positioning holes 101 are determined according to the construction plan. Generally, the setting range of the pipe shed positioning holes 101 is within the 120° range of the tunnel arch, and the number of settings is 27 - 35. And the adjacent pipe shed positioning holes 101 are arranged at equal or unequal distances. Specifically, for the severely unstable area, the pipe shed positioning holes 101 are arranged in a denser manner, and conversely, the number of pipe shed positioning holes 101 can be relatively reduced.

[0075] In step S3, by means of the pipe-shed positioning holes 101 on the simple positioning frame 1, a down-the-hole drill or other drilling equipment is used for the drilling construction of the in-tunnel pipe shed 2. For severely collapsed surrounding rock sections, the pipe-following drill technology should be adopted; the in-tunnel pipe shed 2 uses a φ89 or φ108 grouting steel pipe, and the length of the steel pipe should be controlled within the range of 8 - 15 m, and the pipe-shed driving angle is controlled within the range of 5 - 10°.

[0076] In step S4, after the in-tunnel pipe shed 2 is driven, a grouting equipment is used for high-pressure grouting construction. For general sections, cement mortar with a water-cement ratio of 1:1 (by weight) is used; in water-rich areas, a cement-sodium silicate double slurry can be used. The grouting parameters of the cement-sodium silicate double slurry are as follows: C:S = 1:(0.6 - 1.0) (by volume), the water-cement ratio of the cement slurry is 0.8:1 - 1:1, the modulus of sodium silicate is 2.6 - 2.8, and the concentration of sodium silicate is 35B; the initial grouting pressure is 0.5 - 1.0 MPa, and the termination pressure is 2.0 MPa; before grouting, a on-site grouting test should be carried out, and the grouting parameters should be adjusted according to the actual situation to obtain the pipe-shed grouting construction experience;

[0077] After the grouting is completed, the steel pipe is filled with M20 cement mortar. If necessary, a steel reinforcement cage made of 4 φ20 steel bars can be added inside the pipe shed to improve the stiffness of the pipe-shed pipe body.

[0078] In step S5, the specific construction steps of the built-in pipe-shed bracket structure 3 are as follows:

[0079] (1) The end of the in-tunnel pipe shed 2 is sleeved inside the hollow extension sleeve 3052 of the rotatable connection device, and the in-tunnel pipe shed 2 is tightly clamped through the limiting mechanism 3053 to realize the fixed connection between the hollow extension sleeve 3052 and the in-tunnel pipe shed 2; at this time, the elastic connection rope 3041 lifts the base 301 through the hollow extension sleeve 3052 positioned with the in-tunnel pipe shed 2 to prevent the base 301 from rotating and swinging up and down during the suspended stage below.

[0080] (2) One set of rotatable connection device corresponds to each in-tunnel pipe shed 2. After all the rotatable connection devices are installed, an arc-shaped steel support 306 is erected at the front and rear ends of the base 301 of the rotatable connection device to support the rotatable connection device, and the arc-shaped steel support 306 is fixedly connected with the existing primary support of the tunnel into a whole through the shotcrete connection structure 307; thus, the installation construction of the built-in pipe-shed bracket structure 3 at the end of the in-tunnel pipe shed 2 is completed.

[0081] Specifically, since the end of the in - tunnel pipe - shed 2 is embedded shallowly inside the surrounding rock and there is no good grouting slurry - stopping section, the overall grouting effect is poor. At the same time, the end of the in - tunnel pipe - shed 2 is a collapsed body or a soft and broken section, and the self - stability ability of the tunnel surrounding rock is relatively poor. Therefore, the force at the end of the in - tunnel pipe - shed 2 is mainly the bending of the beam body of the pipe - shed pipe itself. At this time, reliable vertical support structures must be ensured both in front of and behind the pipe - shed. The conventional in - tunnel pipe - shed construction technology cannot provide effective support for the end of the pipe - shed, which is likely to cause the pipe - shed to sink under the vertical load of the surrounding rock in the arch part, and then lead to the overall failure of the pipe - shed. By extending the end of the in - tunnel pipe - shed 2 in the reverse direction and then constructing a reliable built - in pipe - shed bracket structure 3, the above - mentioned construction problems can be effectively solved.

[0082] In step S6, under the protection of the in - tunnel pipe - shed 2, the face excavation and support construction are carried out. The erection construction of the primary support steel frame under the in - tunnel pipe - shed 2 and the shotcrete construction of the primary support are carried out in the way of "excavating one segment and supporting one segment".

[0083] In step S7, the removal process of the pipe - shed bracket structure 3 is opposite to its construction process, specifically as follows:

[0084] 1) Remove two segments of arc - shaped steel supports 306 under the rotatable connecting pipe device;

[0085] 2) Release the limit of the in - tunnel pipe - shed 2 by the limit mechanism 3053, and then remove the rotatable connecting pipe device from the end of the in - tunnel pipe - shed 2. The subsequent construction can reuse it.

[0086] In step S8, after all the rotatable connecting pipe devices are removed, the shotcrete of the primary support in this area is constructed to completely cover the in - tunnel pipe - shed 2 within the primary support. If the end part of the in - tunnel pipe - shed 2 protrudes locally outside the primary support, the protruding part is first cut off.

[0087] So far, all the construction of the in - tunnel pipe - shed 2 is completed, and then the tunnel excavation construction is carried out according to the normal construction steps under the protection of the in - tunnel pipe - shed 2.

[0088] The above - mentioned are only the preferred embodiments of the present invention, and there is no any form of confidential restriction on the present invention. Any simple modification, equivalent change and modification made to the above - mentioned embodiments based on the technical content of the present invention and without departing from the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. An internal pipe-roof support device, characterized in that: It includes a simple positioning frame (1), and the simple positioning frame (1) is the last erected steel arch frame near the tunnel face; a number of pipe shed positioning holes (101) are provided on the simple positioning frame (1), and an in-tunnel pipe shed (2) is provided in the pipe shed positioning holes (101). The in-tunnel pipe shed (2) is inclined upward as a whole and penetrates into the surrounding rock in front of the tunnel face, and a built-in pipe shed bracket structure (3) with reverse elongation is provided at its end; The built-in pipe shed bracket structure (3) includes a rotatable pipe connecting device, and an arc-shaped steel support is provided at the bottom of the rotatable pipe connecting device; The rotatable pipe connecting device includes a base (301), a wedge-shaped cutting groove (302) inclinedly arranged is provided on the base (301), an installation groove (303) is provided on the side near the lower side of the wedge-shaped cutting groove (302) obliquely downward, and an elastic connecting piece (304) is provided on the other side. A pipe extension sleeve assembly (305) is provided in the wedge-shaped cutting groove (302). One end of the pipe extension sleeve assembly (305) is hinged to a hinge shaft arranged in the installation groove (303), and the other end is connected to the elastic connecting piece (304), and the pipe extension sleeve assembly (305) fits with the wedge-shaped cutting groove (302) under the restoring force of the elastic connecting piece (304).

2. The built-in pipe roof support device according to claim 1, characterized in that: The arc-shaped steel support is a spliced temporary arch protection structure arranged along the tunnel contour. The spliced temporary arch protection structure is spliced by I20a type steel I-beams, and is fixedly connected to the existing initial support of the tunnel as a whole through a shotcrete connection structure (307) at the lower part of the steel I-beam.

3. A method for directly constructing a pipe shed in a tunnel, characterized in that: It includes the following steps: S1. According to the instability condition of the tunnel face, use tunnel muck or permeable stone materials to backfill the tunnel face in a reverse pressure manner and form a construction platform (4); S2. Take the last erected steel arch frame near the tunnel face as the simple positioning frame (1), and process a number of pipe shed positioning holes (101) along the tunnel arch contour at the web position of the simple positioning frame (1); S3. Incline upward and drive the in-tunnel pipe shed (2) into the surrounding rock in front of the tunnel face from the pipe shed positioning holes (101); S4. After the in-tunnel pipe shed (2) is driven, use grouting equipment to carry out high-pressure grouting construction on the in-tunnel pipe shed (2); S5. Carry out reverse elongation of the pipe shed along the back of the tunnel face at the end of the in-tunnel pipe shed (2) to form a built-in pipe shed bracket structure (3) with reliable force; S6. Carry out tunnel face excavation and support construction in sequence under the protection of the in-tunnel pipe shed (2); S7: After the excavation tunnel face effectively passes under the collapse body or the soft and broken zone at the end of the pipe shed, and there are no less than 2 - 3 primary support steel I-beams (5) under the in-tunnel pipe shed (2), carry out the demolition construction of the built-in pipe shed bracket structure (3); S8. After all the built-in pipe shed bracket structures (3) are demolished, construct the initial support shotcrete in this area so that the in-tunnel pipe shed (2) is completely covered in the initial support; In step S5, the specific construction steps of the pipe shed bracket structure (3) are: a. Use the hollow extension casing (3052) of the rotatable connecting pipe device to sleeve the end of the in - tunnel pipe shed (2), and use the limit mechanism (3053) to tightly hold and lock the in - tunnel pipe shed (2) to achieve the fixed connection between the hollow extension casing (3052) and the in - tunnel pipe shed (2). At this time, the elastic connection rope (3041) lifts the base (301) through the hollow extension casing (3052) positioned with the in - tunnel pipe shed (2) to prevent the base (301) from rotating and swinging up and down during the suspended stage below. b. Each in - tunnel pipe shed (2) corresponds to a set of rotatable connecting pipe devices. After all the rotatable connecting pipe devices are installed, set up an arc - shaped steel support (306) at the front and rear ends of the base (301) of the rotatable connecting pipe device to support the rotatable connecting pipe device, and use the shotcrete connection structure (307) to fixedly connect the arc - shaped steel support (306) with the existing primary support of the tunnel as a whole. Thus, the installation construction of the in - tunnel pipe shed (2) end built - in pipe shed bracket structure (3) is completed. In step S6, under the protection of the in - tunnel pipe shed (2), carry out the heading face excavation and support construction, and carry out the erection construction of the primary support steel arch and the shotcrete construction of the primary support under the in - tunnel pipe shed (2) in the way of "excavating one segment and supporting one segment".

4. The method for directly constructing the pipe-shed in the tunnel according to claim 3, wherein: In step S1, if the surrounding rock of the heading face deteriorates rapidly but has not developed into a heading face collapse accident, only need to use the tunnel muck or permeable stone materials to backfill the heading face in a reverse pressure manner to form a construction platform (4). If a large - scale collapse or roof fall occurs at the heading face, first use the tunnel muck or permeable stone materials to backfill the heading face in a reverse pressure manner to form a construction platform (4); then spray - concrete or grout the collapsed body to ensure the relative stability of the collapsed body. The above construction shall not block the groundwater drainage channel. When necessary, inclined drainage holes shall be drilled to drain the groundwater.

5. The method for directly constructing the pipe shed in the tunnel according to claim 3, characterized in that: In step S2, use the last erected steel arch near the heading face as a simple positioning frame (1) and carry out simple treatment: 1) Add φ60 or φ76 foot - locking anchor pipes (6) at the arch feet of the steel arch, and control the length within 4.5 - 6.0 m. 2) Use the electric welding cutting method to cut the pipe shed positioning holes (101) at the web position of the simple positioning frame (1). The position and quantity of the pipe shed positioning holes (101) are determined according to the construction plan. The pipe shed positioning holes (101) are set in the range of 120° of the tunnel arch, and the number of settings is 27 - 35, and the adjacent pipe shed positioning holes (101) are set at equal or unequal distances.

6. The method for directly constructing the inner-hole pipe shed according to claim 3, characterized in that: In step S3, with the help of the pipe shed positioning holes (101) on the simple positioning frame (1), use a down - the - hole drill or other drilling equipment to carry out the drilling construction of the portal pipe shed (2). For the sections with serious surrounding rock caving, the follow - the - pipe drill technology should be adopted. The in - tunnel pipe shed (2) uses φ89 or φ108 grouting steel pipes, and the steel pipe length should be controlled within the range of 8 - 15 m, and the pipe shed driving angle is controlled within the range of 5 - 10°.

7. The method for directly constructing the inner-hole pipe shed according to claim 3, wherein: In step S4, after the installation of the inner pipe shed (2) in the tunnel is completed, high-pressure grouting construction is carried out using grouting equipment. After the grouting is completed, the steel pipes are filled with M20 cement mortar, and a steel reinforcement cage made of 4 φ20 steel bars is added inside the pipe shed to improve the stiffness of the pipe shed body.

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