Rapid disposing and passing method for tunnel vault loose body collapse cavity

Abstract

The invention relates to a tunnel vault loose body collapse cavity rapid disposal and passing method. The method comprises the following steps that concrete is sprayed to seal the surface of a collapse cavity body; erecting a profile steel arch frame; meshes are arranged among the arch frames; pre-burying a steel pipe with holes in a cavity formed by the collapsed cavity; a slope is formed near the tunnel face; spraying concrete to seal the steel arch; a steel pipe with holes is pre-buried, cement mortar is poured firstly to consolidate collapsed slag, then concrete is pumped, and finally sand blowing and backfilling are conducted. An advanced grouting small guide pipe is arranged within the 120-degree range of the arch crown in a driving mode, and surrounding rock is reinforced through grouting; the tunnel face is excavated by 1-2 m, and sufficient pipe shed construction space is reserved for the multifunctional drilling machine through proper expanding excavation; a pipe shed is built, and surrounding rock is reinforced through grouting; adjusting the distance between arch frames according to the angle and distance of the pipe shed, and erecting the arch frames; advance grouting small guide pipes are arranged between the pipe sheds; and normally excavating and supporting according to design data and a construction scheme. According to the method, after the tunnel vault collapses, quick closing and filling of the collapse cavity position of the vault are effectively controlled, and continuous occurrence of collapse cavity of the loose body of the vault is prevented.

Description

Technical Field

[0001] This invention patent relates to the technical field of tunnel engineering construction. Specifically, it relates to a method for quickly disposing of and passing through the loose body collapse cavity at the tunnel vault. Background Art

[0002] In tunnel engineering under the condition of soft and fractured surrounding rock, the geological structure is complex, the surrounding rock stability is poor, and the construction risk is high. The face often shows the phenomenon of collapse cavity at the vault of the face due to reasons such as developed surrounding rock fissures, poor bonding force between fissure layers, unfavorable tectonic attitude for the stability of the face, and sudden gushing of groundwater. At present, the treatment plan for the collapse cavity section is to use shotcrete or pumped mortar to backfill the cavity, and use the combination of pipe shed and advanced small pipe to pass through the collapse cavity section and the subsequent soft and fractured section. After the collapse cavity occurs, the main purpose of cavity backfill is to quickly seal the surrounding rock, prevent the further increase of the collapse cavity range, and at the same time restore the contact between the surrounding rock and the initial support to ensure that the surrounding rock and the support structure form a common load-bearing system; the main purpose of driving the pipe shed and advanced small pipe is to share the surrounding rock pressure in front of the collapse cavity section to ensure the stability of the surrounding rock in front of the collapse body. In the actual construction process, the above methods have certain limitations: (1) The surface of the collapse body cannot be effectively and quickly sealed, and the internal cavity backfill is not dense, and there is no effective contact between the surrounding rock and the support; (2) The driving angle of the pipe shed is too large, and an effective arch shed structure cannot be formed to share the surrounding rock pressure in front of the face. After continuous excavation, the loose rock mass between the pipe shed and the tunnel has no support, and it is extremely easy to continue to have a collapse cavity accident; (3) The treatment time of the collapse cavity is too long, which is not conducive to the quick sealing and ring formation of the tunnel support in the soft and fractured surrounding rock, and may cause secondary collapse cavity while affecting the construction progress. Therefore, for the collapse cavity phenomenon in the soft and fractured surrounding rock, adopting a quick and effective cavity backfill method and ensuring the effectiveness of the advanced support are the most effective methods for disposing of the collapse cavity at the vault and passing through the collapse cavity section. No effective solution has been proposed for the problems in the related technology. Summary of the Invention

[0003] Therefore, to solve the above deficiencies, the purpose of the present invention is to provide a method for quickly disposing of and passing through the collapse of the loose body at the tunnel vault in the soft and fractured surrounding rock, overcoming the above deficiencies in the existing products and methods, and being able to effectively ensure the quick sealing of the collapse cavity surface and the effective filling of the cavity after the collapse cavity occurs; at the same time, it can ensure the construction quality of the advanced support in front of the face and ensure the stability of the surrounding rock in front of the face. The present invention improves the operation efficiency of the collapse cavity accident disposal in the soft and fractured surrounding rock, reduces the construction and management costs, and increases the construction safety.

[0004] The present invention is implemented as follows. It constructs a method for quickly disposing of and passing through the collapse cavity of the loose body at the tunnel vault, which is characterized by including the following steps:

[0005] 1) After the collapse occurs, C25 shotcrete is used to spray and seal the surface of the collapse cavity. The spraying thickness is controlled at 15-20cm. On the one hand, it prevents the soft and broken surrounding rock from further weathering and the scope of the loose circle of the vault from further expanding; on the other hand, it seals the water flow channel on the surface of the collapse cavity to prevent further collapse caused by groundwater;

[0006] 2) Under the protection of the self-made anti-rockfall trolley, erect I20b steel arch frames as close to the face as possible, with the arch frame spacing guaranteed to be 40-50cm to provide strong support rigidity and strength;

[0007] 3) Installation and welding between arch frames Steel mesh;

[0008] 4) Pre-embed 5-8 roots in the collapsed cavity or The perforated steel pipe extends into the collapse cavity with the end extending more than 5m beyond the excavation contour or the surface of the collapsed slag, and the other end extending 1m beyond the excavation contour or the surface of the collapsed slag;

[0009] 5) The tunnel face is backfilled to the position of the last steel arch, and a slope is formed near the tunnel face. 10 cm thick shotcrete is sprayed on the tunnel face and slope surface to form a stable tunnel face and steps;

[0010] 6) Spray concrete to seal the newly erected steel arch frame according to the original design plan;

[0011] 7) To ensure the compactness of the collapsed cavity, reduce the load of the backfill material in the cavity, and reduce the impact of rockfall or collapsed bodies on the tunnel lining, first pour cement mortar through the pre-buried steel pipe, and after the cement mortar has solidified the collapsed debris, pump C20 concrete to form a "protective arch", and finally blow sand back to form a buffer layer;

[0012] 8) 3.5m long is built within 120 degrees of the arch Pre-grouting small pipes and grouting to reinforce surrounding rocks. The circumferential spacing of the pre-grouting small pipes is controlled to be 30cm, the overlap length is not less than 2m, the driving angle is controlled between 5-10 degrees, and at least two arch frame pre-grouting small pipes are driven to form a double-layer pre-grouting support above the excavation area in the subsequent expansion process;

[0013] 9) Dig 1-2m deeper and expand the excavation appropriately (at least 40cm) to leave enough space for the multi-functional drilling rig or down-the-hole drilling. Immediately after excavation, spray 10-20cm of shotcrete to seal the exposed surrounding rock;

[0014] 10) Drill a 9m long hole within 120 degrees of the arch Pipe sheds are used to reinforce the surrounding rock through grouting, and the circumferential spacing of the pipe sheds is 40 cm;

[0015] 11) Adjust the spacing of the arch frames according to the angles and positions of the pipe roofs, erect the steel arch frames, make the outer sides of the arch frames closely adhere to the pipe roofs, and weld the connection parts between the pipe roofs and the arch frames;

[0016] 12) Drive the advanced grouting small pipes with a length of 3.5 m between the pipe roofs, so that the advanced small pipes can fill the void area between the pipe roofs as much as possible; 13) Carry out excavation and support according to the normal procedures, and drive the pipe roofs and advanced small pipes according to the surrounding rock conditions during the subsequent construction.

[0017] 13) Excavate and support according to the normal process, and drive pipe roofs and advanced small pipes according to the surrounding rock conditions during subsequent construction.

[0018] In this application, the shotcrete used in step 1 is C25 shotcrete, and the thickness of the shotcrete is controlled within 15 - 20 cm, ensuring at least 15 cm thick.

[0019] In this application, the steel arch frame used in step 2 is I20b I-beam, the spacing of the arch frames is 40 - 50 cm, and the maximum does not exceed 50 cm. Under the protection of the self-made rockfall prevention trolley, the steel arch frames are erected as close as possible to the tunnel face formed after the collapse cavity;

[0020] The steel arch frames erected in step 2 are connected by threaded steel bars, and the connection bars are fixed to the steel arch frames by welding;

[0021] The self-made rockfall prevention trolley is composed of longitudinal beams, cross beams, diagonal braces and columns, and the materials used are I18 or I20b I-beams. The size of the self-made rockfall prevention trolley is adjusted according to the size of the collapse cavity and the shape of the tunnel face formed after the collapse cavity.

[0022] In this application, the steel bar mesh in step 3 uses steel bars, the spacing of the steel bars is 25 cm × 25 cm, and the steel bar mesh is fixed to the steel arch frames by welding.

[0023] In this application, in step 4, or perforated steel pipes are embedded in the cavity of the collapse cavity, the end extending into the collapse body extends at least 5 m beyond the excavation contour line or the surface of the collapsed slag body, and the other end extends more than 1 m, and the orifice is covered with geotextile and removed after the steel arch frame is sealed with shotcrete in step 6.

[0024] In this application, for the first type of collapse cavity, in step 5, the tunnel face is backfilled to the last steel arch frame, and a slope is formed by backfilling near the tunnel face. The backfill slope material can use tunnel muck, and the slope surface is sealed with C20 shotcrete to form a stable step. The thickness of the shotcrete is controlled at about 10 cm. The height and length of the step should meet the angles and lengths of the pipe roofs and advanced small pipes driven by the multi-functional drill (or down-the-hole drill). They vary according to the size of the tunnel section. Generally, the height is 3 - 4 m and the length is 5 - 6 m.

[0025] In this application, in step 7, the collapsed cavity is backfilled in layers. To ensure the compaction degree of the cavity backfill and at the same time reduce the self-load of the backfill material and the impact of falling stones or collapsed slag on the tunnel lining, first, grout mortar is poured through the embedded steel pipes to consolidate the collapsed slag, then C20 concrete is pumped to form a "protective arch", and finally, sand is blown in for backfill to form a buffer layer.

[0026] In this application, in step 8, grouting small pipes with a length of 3.5 m are driven within a 120-degree range of the crown, and the surrounding rock of the crown is grouted. The circumferential spacing of the advanced small pipes is controlled to be no more than 30 cm, the lap length is no less than 2 m, the driving angle is controlled between 5-10 degrees, and at least two sets of arch frames' advanced small pipes are driven to form a double-layer advanced support above the excavation area during the subsequent excavation process. The grouting pressure is controlled between 0.5-1.0 MPa. At the initial stage of grouting, a relatively small grouting pressure is preferably used to fill the fissures, and at the later stage, the grouting pressure should be increased to ensure the diffusion of the grout. The water-cement ratio of the cement slurry is 1:1, and a quick-setting agent is added if necessary.

[0027] In this application, in step 9, the bench method is used for excavation, the excavation footage is 1-2 m, and at the same time, appropriate over-excavation is carried out, and the over-excavation depth is 40-50 cm (at least 40 cm).

[0028] In this application, in step 10, a multi-functional drill (or down-the-hole drill) is used to drive 90-mm-diameter holes with a length of 9 m, the angle is controlled between 5-10 degrees, and the circumferential spacing of the pipe shed is 40 cm;

[0029] In step 11, according to the driving angle and position of the pipe shed, the spacing of the arch frames is adjusted and the arch frames are erected so that the outer side of the arch frame is closely attached to the pipe shed, and the connection between the pipe shed and the arch frame is welded;

[0030] In step 12, advanced small pipes with a length of 3.5 m are driven between the pipe sheds, the circumferential spacing of the advanced small pipes is controlled between 20-30 cm, the driving angle is controlled between 3-5 degrees, and the lap length is controlled to be at least 1.5 m, so that the small pipes can fill the void area between adjacent pipe sheds as much as possible;

[0031] In step 13, normal excavation, support erection, and initial spraying are carried out according to the design plan. In subsequent cycles, advanced small pipes and pipe sheds are continuously constructed according to the on-site conditions. The lap length of the advanced small pipes is not less than 1.5 m, and the lap length of the pipe shed is not less than 3 m.

[0032] The present invention has the following advantages: The invention relates to a method for quickly disposing of and passing through a cavity formed by loose materials in the tunnel vault, comprising the following steps: (1) spraying concrete to seal the surface of the cavity; (2) erecting a steel arch frame under the protection of a self-made rockfall protection trolley, making the steel arch frame as close as possible to the heading face; (3) arranging mesh sheets between the arch frames; (4) embedding perforated steel pipes in the cavity formed by the cavity; (5) backfilling the heading face to the position of the last steel arch frame, and forming a slope near the heading face, and spraying concrete on the surface of the slope to form a stable step; (6) spraying concrete to seal the steel arch frame; (7) through the embedded perforated steel pipes, first grouting cement mortar to consolidate the collapsed slag, then pumping concrete, and finally backfilling with sand; (8) driving 3.5 m long advanced grouting small pipes, and grouting to reinforce the surrounding rock, driving at least the distance of two steel arch frames, the circumferential spacing of the advanced small pipes is 30 cm, and the lap length is guaranteed to be at least 2 m, forming a double-layer advanced support above the subsequent excavation area; (9) excavating the heading face 1-2 m, and appropriately enlarging the excavation (at least 40 cm) to leave enough space for the pipe shed construction of the multi-functional drill; (10) driving 9 m long pipe shed, and grouting to reinforce the surrounding rock; (11) adjusting the spacing of the arch frames according to the angle and distance of the pipe shed, erecting the arch frames, making the outside of the arch frames closely adhere to the pipe shed, and welding the connection between the pipe shed and the arch frames; (12) driving 3.5 m long advanced grouting small pipes between the pipe sheds; (13) normally excavating and supporting according to the design data and construction plan. The effective effect of the present invention is: it can effectively control the rapid sealing and filling of the cavity position in the tunnel vault after the cavity occurs, preventing the continuous occurrence of the cavity formed by loose materials in the tunnel vault. In addition, this method can effectively control the driving angle of the pipe shed, solve the problem that the pipe shed angle is too large due to the small spacing of the arch frames in the soft and broken surrounding rock, and has no supporting effect on the front surrounding rock, ensuring the construction quality of the pipe shed in the soft and broken surrounding rock and the safety of subsequent construction. Brief Description of the Drawings

[0033] Figure 1 is the longitudinal section view of a method for quickly disposing of and passing through a cavity formed by loose materials in the tunnel vault of the present invention;

[0034] Figure 2 is the schematic diagram of a self-made rockfall protection trolley of a method for quickly disposing of and passing through a cavity formed by loose materials in the tunnel vault of the present invention;

[0035] Figure 3 are steps 1-3 of a method for quickly disposing of and passing through a cavity formed by loose materials in the tunnel vault of the present invention;

[0036] Figure 4 are steps 4-6 of a method for quickly disposing of and passing through a cavity formed by loose materials in the tunnel vault of the present invention;

[0037] Figure 5It is step 7 of a method for rapid disposal and crossing of a loose body collapse cavity in the tunnel vault of the present invention;

[0038] Figure 6 It is step 8 of a method for rapid disposal and crossing of a loose body collapse cavity in the tunnel vault of the present invention;

[0039] Figure 7 It is steps 9 - 10 of a method for rapid disposal and crossing of a loose body collapse cavity in the tunnel vault of the present invention;

[0040] Figure 8 It is steps 11 - 12 of a method for rapid disposal and crossing of a loose body collapse cavity in the tunnel vault of the present invention;

[0041] Figure 9 It is step 13 of a method for rapid disposal and crossing of a loose body collapse cavity in the tunnel vault of the present invention.

[0042] Among them: Figure 1 In it: 1. Sand - blowing backfill buffer layer; 2. Pumped - concrete "protective arch" layer; 3. Consolidation layer of the collapse cavity; 4. Surface of the collapse cavity; 5. Embedded perforated steel pipe; 6. Backfill step around the heading face; 7. Pipe shed; 8. Advance small - diameter pipe; 9. Heading face; 10. Lower bench; 11. Upper bench; 12. Steel - section arch frame; 13. Excavation - expansion area;

[0043] Figure 2 In it: 1. I - beam longitudinal beam; 2. I - beam cross beam; 3. Column; 4. Longitudinal diagonal brace; 5. Transverse diagonal brace. Specific embodiments

[0044] The following will combine with the attached Figures 1 - 9 The present invention will be described in detail. The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0045] The present invention provides a method for rapid disposal and crossing of a loose body collapse cavity in the tunnel vault by improvement. The disposal measures for the first - type collapse cavity include the following steps:

[0046] 1) Use C25 shotcrete to seal the surface of the collapse cavity, and the spraying thickness is 15 - 20 cm.

[0047] 2) Erect I20b steel - section arch frames adjacent to the heading face, with the arch - frame spacing of 40 - 50 cm. The number of erected arch frames is determined according to the distance between the last arch frame before the collapse cavity and the heading face after the collapse cavity, ensuring that the last erected steel - section arch frame is close to the heading face. The space between the arch frames is Welding connection of ribbed steel bars.

[0048] 3) Weld wire mesh between the arch supports. Welding of wire mesh.

[0049] 4) Embed in the cavity of the collapsed area or perforated steel pipes.

[0050] 5) Backfill the heading face up to the last set of steel arch supports, and backfill near the heading face to form a slope. Spray concrete to seal the heading face and the slope to form a stable heading face and working bench.

[0051] 6) According to the original design scheme, use shotcrete to seal the newly erected steel section arch supports.

[0052] 7) Through the embedded perforated steel pipes, backfill the cavity of the collapsed area in layers. First, pour cement mortar, then pump C20 concrete, and finally backfill with sand.

[0053] 8) In the 120-degree range of the arch crown, use 3.5m long advance small pipes to grout and reinforce the area within 120 degrees of the arch crown. The circumferential spacing of the advance small pipes is 30cm, the lap length is not less than 2m, the driving angle is controlled between 5 - 10 degrees, the water-cement ratio of the cement slurry used is 1:1, the grouting pressure is 0.5 - 1.0MPa. At the initial stage of grouting, it is advisable to grout with a relatively small pressure to make the slurry fill the cracks. At the final stage of grouting, it is advisable to use a relatively high grouting pressure to make the slurry spread.

[0054] 9) After the slurry has solidified, excavate and advance the heading face by 1 - 2m, with an excavation depth of 40 - 50cm, leaving enough operating space for the multi-functional drill rig (or down-the-hole drill) to install the pipe shed.

[0055] 10) Use a multi-functional drill rig (or down-the-hole drill) to drive 9m long pipe shed, with the drilling angle controlled between 5 - 10 degrees, and the circumferential spacing of the pipe shed is 40cm.

[0056] 11) Adjust the spacing of the arch supports according to the angle and position of the pipe shed, erect the arch supports, make the outer side of the arch supports close to the pipe shed, and weld the connection between the pipe shed and the arch supports.

[0057] 12) Drive 3.5m long advance small pipes between the pipe sheds. The circumferential spacing of the advance small pipes is controlled between 20 - 30cm, making the advance small pipes fill the area between the pipe sheds as much as possible, with the angle controlled between 3 - 5 degrees and the lap length controlled to be at least 1.5m.

[0058] 13) Excavation, erection of supports and support are carried out according to the original design plan. In subsequent excavation cycles, pipe roofs and advanced small ducts are constructed according to the surrounding rock conditions on site. The lap length of the pipe roof is not less than 3m, and the lap length of the advanced small duct is not less than 1.5m.

[0059] The embodiment of the present invention belongs to a method for rapid disposal and crossing of loose body collapse cavities in the tunnel vault. When specifically used, for the first type of collapse cavity situation, according to the present invention, the implementation steps are as follows: 1) Use C25 shotcrete to seal the surface of the collapse cavity, and the spraying thickness is 15 - 20 cm; 2) Under the protection of a self-made rockfall prevention trolley, erect I20b steel arch frames as close as possible to the heading face, with the arch frame spacing being 40 - 50 cm, and the arch frames are welded and connected with threaded steel bars; 3) The arch frames are welded with steel wire mesh; 4) Embed or perforated steel pipes in the cavity of the collapse cavity; 5) Backfill the heading face to the position of the last steel arch frame, and backfill near the heading face to form a slope. Spray 10 cm of concrete to seal the heading face and the slope to form a stable heading face and a bench. The height of the bench is 3 - 4m, and the length of the bench is determined according to the on-site construction conditions to facilitate the drilling of the multi-functional drill (or down-the-hole drill); 6) Seal the newly erected steel arch frames according to the original design plan; 7) Backfill the cavity of the collapse cavity in layers. First, pour cement mortar to consolidate the collapsed slag body, then form a "protective arch" with C20 concrete, and finally backfill with sand to form a buffer layer; 8) Drive 3.5m long advanced small ducts within a 120-degree range at the vault, and grout to reinforce the surrounding rock. The circumferential spacing of the advanced small ducts is 30 cm, the lap length is not less than 2m, and the driving range is at least two steel arch frames to form a double-layer advanced support above the subsequent excavation area; 9) Excavate 1 - 2m and appropriately expand the excavation (at least 40 cm) to provide working space for the construction of the pipe roof; 10) Drive 9m long pipe roofs, and the circumferential spacing of the pipe roofs is 40 cm; 11) Adjust the arch frame spacing according to the angle and position of the pipe roof, erect the arch frames, make the outer side of the arch frames closely adhere to the pipe roof, and weld the connection between the pipe roof and the arch frames; 12) Drive 3.5m long advanced small ducts between the pipe roof voids to make the advanced small ducts fill the void area between the pipe roofs as much as possible; (13) Carry out excavation and support according to the normal process, and drive pipe roofs and advanced small ducts according to the surrounding rock geological conditions. The lap length of the pipe roof is not greater than 3m, and the advanced small duct is not greater than 1.5m.

[0060] In summary, by means of the above technical method of the present invention, the cavity behind the support can be quickly backfilled after the collapse cavity occurs, ensuring the degree of compaction of the cavity backfill and the contact between the surrounding rock and the primary support; effectively controlling the driving angle of the pipe shed, ensuring the stabilizing effect of the pipe shed in the tunnel on the loose rock mass in the front vault. It solves the problem of rapid disposal and crossing when the collapse cavity occurs in the tunnel vault in soft and fractured surrounding rock, improves the operation efficiency, reduces the construction and management costs, increases the construction safety, and has certain reference and guiding effects on the construction of similar surrounding rock.

[0061] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for quickly handling and overcoming the collapse of loose bodies in a tunnel vault, characterized in that: The steps include: 1) After the collapse occurs, C25 shotcrete is used to spray and seal the surface of the collapse cavity. The spraying thickness is controlled at 15-20cm. On the one hand, it prevents the soft and broken surrounding rock from further weathering and the scope of the loose circle of the vault from further expanding; on the other hand, it seals the water flow channel on the surface of the collapse cavity to prevent further collapse caused by groundwater; 2) Under the protection of the self-made anti-rockfall trolley, erect I20b steel arch frames as close to the face as possible, with the arch frame spacing guaranteed to be 40-50cm to provide strong support rigidity and strength; 3) Installation and welding between arch frames 25cm×25cm Steel mesh; 4) Pre-embed 5-8 roots in the collapsed cavity or The perforated steel pipe extends into the collapse cavity with the end extending more than 5m beyond the excavation contour or the surface of the collapsed slag, and the other end extending 1m beyond the excavation contour or the surface of the collapsed slag; 5) The tunnel face is backfilled to the position of the last steel arch, and a slope is formed near the tunnel face. 10 cm thick shotcrete is sprayed on the tunnel face and slope surface to form a stable tunnel face and steps; 6) Spray concrete to seal the newly erected steel arch frame according to the original design plan; 7) To ensure the compactness of the collapsed cavity, reduce the load of the backfill material in the cavity, and reduce the impact of rockfall or collapsed bodies on the tunnel lining, firstly, cement mortar is poured through the pre-buried steel pipe, and after the cement mortar has solidified the collapsed debris, C20 concrete is pumped to form a "protective arch", and finally sand is blown back to form a buffer layer; 8) 3.5m long is built within 120 degrees of the arch Pre-grouting small pipes and grouting to reinforce surrounding rocks. The circumferential spacing of the pre-grouting small pipes is controlled to be 30cm, the overlap length is not less than 2m, the driving angle is controlled between 5-10 degrees, and at least two arch frame pre-grouting small pipes are driven to form a double-layer pre-grouting support above the excavation area in the subsequent expansion process; 9) Dig 1-2m deeper and expand the excavation appropriately (at least 40cm) to leave enough space for the multi-functional drilling rig or down-the-hole drilling. Immediately after excavation, spray 10-20cm of shotcrete to seal the exposed surrounding rock; 10) Drill a 9m long hole within 120 degrees of the arch Pipe sheds are used to reinforce the surrounding rock through grouting, and the circumferential spacing of the pipe sheds is 40 cm; 11) Adjust the distance between the arch frames according to the angle and position of the pipe shed, erect the steel arch frame, make the outer side of the arch frame close to the pipe shed, and weld the connection between the pipe shed and the arch frame; 12) 3.5m long pipe racks are installed between Pre-grouting small conduits to fill the gaps between pipe racks as much as possible; 13) Carry out excavation and support according to normal procedures. In subsequent construction, set up pipe racks and advance small guide tubes according to the surrounding rock conditions.

2. A method for rapidly handling and overcoming a tunnel vault loose body collapse cavity according to claim 1, characterized in that: The shotcrete used in step 1 is C25 shotcrete, and the thickness of the shotcrete is controlled at 15-20 cm, ensuring that it is at least 15 cm thick.

3. A method for rapidly handling and overcoming a tunnel vault loose body collapse cavity according to claim 1, characterized in that: The steel arch frame used in step 2 is I20b I-steel, the arch frame spacing is 40-50cm, and the maximum does not exceed 50cm. Under the protection of a homemade anti-rockfall trolley, the steel arch frame is erected as close as possible to the tunnel face formed after the collapse cavity; The steel arch frame erected in step 2 is Threaded steel bar connection, the connecting bar and the steel arch frame are fixed by welding; The self-made anti-rockfall trolley is composed of longitudinal beams, cross beams, diagonal braces and columns. The material used is I18 or I20b I-beams. The size of the self-made anti-rockfall trolley is adjusted according to the size of the collapsed cavity and the shape of the palm face formed after the collapse.

4. A method for rapidly handling and overcoming a tunnel vault loose body collapse cavity according to claim 1, characterized in that: The steel mesh in step 3 is The steel bars have a spacing of 25cm x 25cm, and the steel mesh is fixed to the steel arch frame by welding.

5. The method for quickly handling and overcoming the collapse of loose bodies in a tunnel vault according to claim 1 is characterized in that: In step 4, the collapsed cavity is pre-buried or The perforated steel pipe should extend into the collapse cavity at least 5m beyond the excavation contour line or the surface of the collapse debris, and the other end should extend more than 1m. Geotextile should be used to cover the hole opening, which should be removed after the steel arch frame is sealed with concrete in step 6.

6. A method for rapidly handling and overcoming a tunnel vault loose body collapse cavity according to claim 1, characterized in that: In step 5, the face is backfilled to the last steel arch, and a slope is backfilled near the face. The backfill slope material can be cave slag, and the slope surface is sealed with C20 sprayed concrete to form a stable step. The thickness of the sprayed concrete is controlled at about 10 cm. The height and length of the step should meet the angle and length of the pipe shed and the advance small guide tube set by the multi-functional drilling rig or down-the-hole drilling. It varies according to the size of the tunnel section. The height is generally 3-4m, and the length is generally 5-6m.

7. A method for rapidly handling and overcoming a tunnel vault loose body collapse cavity according to claim 1, characterized in that: In step 7, the collapsed cavity is backfilled in layers. To ensure the compactness of the collapsed cavity and to reduce the load of the backfill material itself and the impact of falling rocks or collapsed debris on the tunnel lining, cement mortar is first poured through the pre-buried steel pipe to consolidate the collapsed debris, and then C20 concrete is pumped to form a "protective arch", and finally sand is blown back to form a buffer layer.

8. The method for quickly handling and overcoming the collapse of loose bodies in a tunnel vault according to claim 1 is characterized in that: In step 8, a 3.5m long Grouting small pipes, and grouting is carried out on the surrounding rock of the arch. The circumferential spacing of the advance small pipes is controlled to be no more than 30cm, the lap length is no less than 2m, the driving angle is controlled between 5-10 degrees, and at least two arch frame advance small pipes are driven to form a double-layer advance support above the excavation area in the subsequent expansion process. The grouting pressure is controlled between 0.5-1.0MPa. In the initial stage of grouting, the cracks should be filled with a smaller grouting pressure, and the grouting pressure should be increased in the later stage to ensure the diffusion of the slurry. The water-cement ratio of cement slurry is 1:1, and an accelerator is added when necessary.

9. A method for rapidly handling and overcoming a tunnel vault loose body collapse cavity according to claim 1, characterized in that: In step 9, the excavation is carried out by using the step method, the excavation depth is 1-2m, and appropriate excavation is carried out at the same time, and the excavation depth is 40-50cm.

10. A method for rapidly handling and overcoming a tunnel vault loose body collapse cavity according to claim 1, characterized in that: In step 10, a 9m long 90mm borehole is drilled using a multifunctional drilling rig or a down-the-hole drill, the angle is controlled between 5-10 degrees, and the annular spacing of the pipe rack is 40cm; In step 11, according to the angle and position of the pipe shed, the arch frame spacing is adjusted and the arch frame is erected, so that the outer side of the arch frame is close to the pipe shed, and the connection between the pipe shed and the arch frame is welded; In step 12, a 3.5 m long The circumferential spacing of the leading small conduits is controlled at 20-30cm, the setting angle is controlled at 3-5 degrees, and the overlap length is controlled to be at least 1.5m, so that the small conduits can fill the gaps between adjacent pipe racks as much as possible; In step 13, normal excavation, erection and initial spraying are carried out according to the design plan. In the subsequent cycle, the advance small duct and pipe rack are continuously constructed according to the site conditions. The overlap length of the advance small duct is not less than 1.5m, and the overlap length of the pipe rack is not less than 3m.

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