阅读说明：本技术 一种隧道开挖支护后围岩侵限变形的主动撑护结构及方法 (Active supporting and protecting structure and method for invasion-limited deformation of surrounding rock after tunnel excavation and supporting ) 是由 王凯 薛志超 王德明 于 2021-09-17 设计创作，主要内容包括：本发明涉及一种隧道开挖支护后围岩侵限变形的主动撑护结构及方法,在隧道内设置永久钢拱架和永久性防护网,且在永久性防护网表面喷射永久喷浆体；在垂直于隧道进深方向,设置有放射状均匀分布的钻孔,钻孔一端插入用于注浆固定的抗拉套管,另一端固定连接有可焊接套管接头；另外本申请提出的一种隧道开挖支护后围岩侵限变形的主动撑护方法,通过建立永久主动撑护系统实现隧道易出现塌陷区域的加固。本方法把隧道开凿过程的人为扰动出现侵限、坍塌的地质灾害的被动治理,转换为由抗拉套管和与之连接的钢拱架形成的主动支撑系统,结构简单、施工方便、效率高,有效实现隧道易坍塌围岩段的整体加固稳定性。(The invention relates to an active supporting and protecting structure and method for invasion limit deformation of surrounding rock after tunnel excavation supporting, wherein a permanent steel arch frame and a permanent protective net are arranged in a tunnel, and permanent grout is sprayed on the surface of the permanent protective net; drilling holes are radially and uniformly distributed in the direction perpendicular to the depth direction of the tunnel, one end of each drilling hole is inserted into a tensile sleeve for grouting fixation, and the other end of each drilling hole is fixedly connected with a weldable sleeve joint; in addition, according to the active supporting and protecting method for the invasion limit deformation of the surrounding rock after tunnel excavation and supporting, the reinforcing of the area where the tunnel is prone to collapse is achieved by establishing the permanent active supporting and protecting system. The method converts the passive treatment of the geological disasters of invasion limit and collapse caused by artificial disturbance in the tunnel excavation process into an active support system formed by the tensile sleeve and the steel arch frame connected with the tensile sleeve, has simple structure, convenient construction and high efficiency, and effectively realizes the integral reinforcement stability of the surrounding rock section easy to collapse of the tunnel.)

1. An active supporting and protecting structure for intrusion limit deformation of surrounding rocks after tunnel excavation supporting is characterized in that a permanent steel arch frame (10-2) and a permanent protective net (11-2) are arranged in a tunnel, and permanent spraying slurry (12-2) is sprayed on the surface of the permanent protective net (11-2);

meanwhile, in the direction perpendicular to the depth of the tunnel, radially and uniformly distributed drill holes (1) are formed in the drilling construction space (15) along the directions of collapse invasion limit surrounding rocks (4), tunnel excavation contour lines (5), disturbance loose surrounding rocks (3) and original surrounding rocks (2), one end of each drill hole (1) is inserted into a tensile sleeve (7) for grouting fixation, and the other end of each drill hole is fixedly connected with a weldable sleeve joint (13).

2. The active supporting structure for the invasion limit deformation of the surrounding rock after the tunnel excavation supporting according to claim 1, wherein the drill holes (1) are uniformly distributed in a row in the same annular cross section perpendicular to the depth direction of the tunnel and are arranged in a plurality of rows along the depth direction of the tunnel, and the row spacing of the two adjacent rows of drill holes (1) is the same as the row spacing of the primary supporting steel arch frames of the tunnel design.

3. The active bracing structure for limiting surrounding rock invasion deformation after tunnel excavation bracing according to claim 1, characterized in that the drilling hole (1) comprises a probing hole (1-1) for probing the thickness of collapse limiting surrounding rock (4) and the thickness and depth of disturbance loose surrounding rock (3) and a grouting hole (1-2) for installing a casing.

4. The active supporting and protecting structure for the invasion limit deformation of the surrounding rock after the tunnel excavation supporting according to claim 1, is characterized in that a temporary supporting and protecting structure is built before the active supporting and protecting structure for the tunnel in which the invasion limit deformation of the surrounding rock occurs, the temporary supporting and protecting structure comprises a temporary steel arch (10-1) and a temporary protective net (11-1), and temporary guniting body (12-1) is sprayed on the surface of the temporary protective net (11-1); meanwhile, a tensile sleeve (7) for grouting fixation is inserted into one end of the drill hole (1), and a detachable short sleeve (9) is fixedly connected to the other end of the drill hole.

5. An active supporting and protecting method for invasion limit deformation of surrounding rock after tunnel excavation and supporting comprises the following steps:

(1) reinforcing and supporting surrounding rock with collapse and invasion limit

Reinforcing and supporting deformed steel arches existing at collapse invasion limiting surrounding rocks (4), then cleaning a tunnel space for adding a temporary steel arch (10-1) again, laying a temporary protective screen (11-1) at one end of the temporary steel arch (10-1) supporting the inner wall of the tunnel, and spraying temporary guniting body (12-1) on the surface of the temporary protective screen (11-1);

(2) arranging boreholes in a drilling construction space

The method comprises the following steps that drill holes (1) are uniformly arranged in the circumferential direction of a drilling construction space (15) in the direction perpendicular to the depth direction of a tunnel, and the drill holes (1) sequentially penetrate through collapse invasion limit surrounding rocks (4), tunnel excavation contour lines (5), disturbance loose surrounding rocks (3) and original surrounding rocks (2) to form a radial shape; meanwhile, the drill holes (1) are uniformly distributed in a row in the same annular section; the holes are arranged in a plurality of rows along the depth direction of the tunnel, and the row spacing of two adjacent rows of the drill holes (1) is the same as the row spacing of the primary support steel arch centering of the tunnel design;

the borehole (1) is internally provided with a probing hole (1-1) for probing the thickness of collapse invasion surrounding rock (4) and the thickness and depth of disturbance loose surrounding rock (3) and a grouting hole (1-2) for installing a casing;

(3) establishing temporary active supporting and protecting system

The temporary active supporting and protecting system comprises a tensile sleeve (7) and a detachable short sleeve (9), wherein the tensile sleeve (7) is detachably connected with the detachable short sleeve (9); inserting the connected tensile sleeve (7) and the detachable short sleeve (9) into the drill hole (1) and then grouting, forming a grouting consolidation body (6) between the tensile sleeve (7) and the wall of the drill hole (1), forming a grouting sealing solid (8) after the grouting of the disturbed loose surrounding rock (3), and consolidating the grouting consolidation body (6), the grouting sealing solid (8) and the undisturbed surrounding rock (2);

(4) establishing permanent active supporting and protecting system

After a detachable short sleeve (9), a temporary steel arch (10-1) and a temporary protective net (11-1) of the temporary active supporting and protecting system are dismantled, collapse invasion surrounding rocks (4) in a tunnel are cleaned to a tunnel excavation contour line (5), then a permanent protective net (11-2) and a permanent steel arch (10-2) are laid on the inner surface of a tunnel drilling construction space (15), two adjacent rows of permanent steel arches (10-2) are connected through reinforcing steel bars (14), permanent spraying slurry (12-2) is sprayed on the surface of the permanent protective net (11-2), and a weldable sleeve joint (13) is installed at the position of the detachable short sleeve (9);

when the drilling construction space (15) is large, the construction of multiple rows of drill holes (1) is completed at one time: after the construction of one row of drill holes (1) is finished, installing one row of temporary active supporting and protecting systems until all the temporary active supporting and protecting systems are installed, then removing the temporary active supporting and protecting systems row by row from the entrance to the tunnel along the depth direction of the tunnel, cleaning the collapse invasion limit surrounding rocks (4) in the same row range in the tunnel to a tunnel excavation contour line (5), and then installing permanent active supporting and protecting systems in the same row; the rows are gradually advanced until the permanent safe active supporting and protecting system is completely finished;

when the drilling construction space (15) is small, firstly constructing three rows of drill holes (1) from the hole opening to the hole along the depth direction of the tunnel, wherein the advancing distance of each row is 1.5m, and completely installing temporary active supporting and protecting systems; then, disassembling the temporary active supporting and protecting system in the outermost row, cleaning the collapse invasion limit surrounding rocks (4) in the same row range in the tunnel to a tunnel excavation contour line (5), and installing the permanent active supporting and protecting system; then, constructing a row of drill holes (1) at the other end of the tunnel in the depth direction, and installing a temporary active supporting and protecting system; and (3) removing one row of temporary active supporting and protecting systems according to the tunnel portal, and installing one row of temporary active supporting and protecting systems at the other end inside the tunnel in a row-by-row construction sequence until all collapse invasion surrounding rock (4) areas are all provided with permanent active supporting and protecting systems.

6. The active supporting method for the invasion limit deformation of the surrounding rock after the tunnel excavation supporting according to claim 5, wherein when the collapse invasion limit section is treated, the lithology in front of the tunnel is not changed, or the tunnel section which generates the invasion limit deformation of the surrounding rock is treated, the method comprises the following steps:

(1) arranging boreholes in a drilling construction space

The method comprises the following steps that drill holes (1) are uniformly arranged in the circumferential direction of a drilling construction space (15) in the direction perpendicular to the depth direction of the tunnel, and the drill holes (1) sequentially penetrate through the drilling construction space (15), a tunnel excavation contour line (5), a disturbance loose surrounding rock (3) and an original surrounding rock (2) and are radial; meanwhile, the drill holes (1) are uniformly distributed in a row in the same annular section; the holes are arranged in a plurality of rows along the depth direction of the tunnel, and the row spacing of two adjacent rows of the drill holes (1) is the same as the row spacing of the primary support steel arch centering of the tunnel design; the drill hole (1) comprises a probing hole (1-1) for probing the thickness of collapse limiting surrounding rock (4) and the thickness and the depth of disturbance loose surrounding rock (3) and a grouting hole (1-2) for installing a casing;

(2) establishing permanent active supporting and protecting system

Inserting the connected tensile sleeve (7) into the drill hole (1) and then grouting, forming a grouting consolidation body (6) between the tensile sleeve (7) and the wall of the drill hole (1), forming a grouting sealing solid (8) after grouting of the disturbed loose surrounding rock (3), and consolidating the grouting consolidation body (6) and the grouting sealing solid (8) with the undisturbed surrounding rock (2); a weldable sleeve joint (13) is arranged at one end of the tunnel excavation contour line (5) of the tensile sleeve (7); then, a permanent protective net (11-2) is laid on the inner surface of the surrounding rock at the tunnel excavation contour line (5), a permanent steel arch (10-2) is installed, the permanent steel arch (10-2) is fixedly connected with the weldable casing joint (13), and permanent spraying slurry (12-2) is sprayed on the surface of the permanent protective net (11-2); two adjacent rows of permanent steel arch frames (10-2) are connected through reinforcing steel bars (14).

7. The active supporting method for the invasion limit deformation of the surrounding rock after tunnel excavation supporting according to claim 5, wherein the hole distance between two adjacent open holes of the same row of drill holes (1) at the position close to the inner surface of the tunnel is 1-1.5 m.

8. The active supporting method for invasion-limited deformation of surrounding rock after tunnel excavation supporting according to claim 5, characterized in that the number ratio of the probing holes (1-1) and the grouting holes (1-2) in the drill holes (1) with the same cross section perpendicular to the depth direction of the tunnel is 1: 2.

9. The active supporting method for the invasion limit deformation of the surrounding rock after tunnel excavation supporting according to claim 5, characterized in that the depth of the grouting drill hole (1-2) into the undisturbed surrounding rock (2) is more than or equal to 2 times of the thickness of the disturbed loose surrounding rock (3).

10. The active supporting method for limiting wall rock invasion deformation after tunnel excavation supporting according to claim 5, characterized in that one end of the weldable casing pipe joint (13) connected with the tensile casing pipe (7) is arranged at a position, 30cm away from a tunnel excavation contour line (5), of the disturbed loose wall rock (3).

Technical Field

The invention relates to the technical field of tunnel safety construction, in particular to an active supporting and protecting structure and method for invasion limit deformation of surrounding rock after tunnel excavation and supporting.

Background

When a plurality of tunnels pass through unfavorable geological surrounding rocks such as a broken zone and the like, particularly pass through the surrounding rocks such as gneiss with particularly serious development of bedding joints, the phenomena of sinking, serious deformation and even collapse of the surrounding rocks on the top plate of the tunnel after being disturbed often occur. Because the surrounding rock of the top plate is damaged, the stability of the surrounding rock is poor, and the tunnel shallow surrounding rock even has extremely broken or powdery phenomena under the dual actions of pressure and weathering erosion. When the deformation section is repaired, after the broken part in the tunnel invasion limit section is cleaned, the surrounding rock on the deformation section can continue to sink and peel off, and the phenomenon of invasion limit appears again, so that the phenomenon of more collapse after cleaning is caused. When the surrounding rock is seriously unstable, the finished primary support is crushed and deformed by the dead weight pressure of the surrounding rock. The tunnel excavation engineering is difficult to carry out, and the construction progress is seriously hindered. Therefore, a structure capable of improving subsidence, invasion and collapse of the tunnel in unfavorable geology is necessary, and occurrence of such danger is prevented as much as possible in tunnel construction, thereby increasing safety of the tunnel.

Disclosure of Invention

In view of the above, the invention provides an active supporting and protecting structure and method for limiting and deforming invasion of surrounding rock after tunnel excavation and supporting in order to avoid tunnel deformation or repair a deformed tunnel.

An active supporting and protecting structure for limiting and deforming invasion of surrounding rocks after tunnel excavation supporting comprises a permanent steel arch frame and a permanent protective net, and permanent spraying slurry is sprayed on the surface of the permanent protective net; meanwhile, in the direction perpendicular to the depth of the tunnel, radially and uniformly distributed drill holes are arranged in the drilling construction space along the directions of collapse invasion limit surrounding rock, tunnel excavation contour line, disturbance loose surrounding rock and original surrounding rock, one end of each drill hole is inserted into a tensile sleeve for grouting fixation, and the other end of each drill hole is fixedly connected with a weldable sleeve joint.

On the basis of the scheme, the drill holes are uniformly distributed in a row in the same annular cross section perpendicular to the depth direction of the tunnel and are arranged in multiple rows along the depth direction of the tunnel, and the row spacing of the two adjacent rows of drill holes is the same as that of the primary support steel arch frame in the tunnel design.

The drill hole comprises a probing hole for probing the thickness of collapse limiting surrounding rock and the thickness and the depth of disturbance loose surrounding rock and a grouting hole for installing a casing.

The invention also provides an active supporting and protecting method for invasion limit deformation of surrounding rock after tunnel excavation and supporting, which comprises the following steps:

(1) reinforcing and supporting surrounding rock with collapse and invasion limit

Reinforcing and supporting deformed steel arches existing at collapse invasion limiting surrounding rocks, cleaning a tunnel space for adding temporary steel arches again, laying a temporary protective net at one end of the temporary steel arch for supporting the inner wall of the tunnel, and spraying temporary guniting body on the surface of the temporary protective net;

(2) arranging boreholes in a drilling construction space

The method comprises the following steps that drill holes are uniformly arranged in the circumferential direction of a drilling construction space in the direction perpendicular to the depth direction of the tunnel, and the drill holes sequentially penetrate through the drilling construction space, collapse invasion limiting surrounding rocks, tunnel excavation contour lines, disturbed loose surrounding rocks and original surrounding rocks to form a radial shape; meanwhile, the drill holes are uniformly distributed in a row in the same circumferential section; the holes are arranged in a plurality of rows along the depth direction of the tunnel, and the row spacing of the two adjacent rows of holes is the same as that of the primary support steel arch frame designed for the tunnel;

the borehole is provided with a probing hole for probing the thickness of collapse invasion limiting surrounding rock and the thickness and the depth of disturbance loose surrounding rock and a grouting hole for installing a casing;

(3) establishing temporary active supporting and protecting system

The temporary active supporting and protecting system comprises a tensile sleeve and a detachable short sleeve, and the tensile sleeve is detachably connected with the detachable short sleeve; inserting the connected tensile sleeve and the detachable short sleeve into a drill hole and then grouting, forming a grouting consolidation body between the tensile sleeve and the drill hole wall, forming grouting sealing solid after the disturbance loose surrounding rock is formed by grouting, and consolidating the grouting consolidation body, the grouting sealing solid and the undisturbed surrounding rock;

(4) establishing permanent active supporting and protecting system

After a detachable short sleeve, a temporary steel arch and a temporary protective net of the temporary active supporting and protecting system are dismantled, collapse invasion limiting surrounding rocks in the tunnel are cleaned to reach the tunnel excavation contour line, then a permanent protective net and a permanent steel arch are laid on the inner surface of a tunnel drilling construction space, two adjacent rows of permanent steel arches are connected through reinforcing steel bars, permanent grout is sprayed on the surface of the permanent protective net, and a weldable sleeve joint is installed at the position of the detachable short sleeve;

when the drilling construction space is large, the construction of multiple rows of drill holes is completed at one time: after the one-row grouting drilling construction is finished, a one-row temporary active supporting and protecting system is installed until all temporary active supporting and protecting systems are installed, then the temporary active supporting and protecting systems are removed row by row from the entrance to the inside of the tunnel along the depth direction of the tunnel, the collapse invasion limit surrounding rocks in the same row range in the tunnel are cleaned to reach the tunnel excavation contour line, and then the permanent active supporting and protecting systems in the same row are installed; the rows are gradually advanced until the permanent safe active supporting and protecting system is completely finished;

when the drilling construction space is small, firstly constructing three rows of drill holes from the hole opening to the hole along the depth direction of the tunnel, wherein the advancing distance of each row is 1.5m, and completely installing temporary active supporting and protecting systems; then, disassembling the temporary active supporting and protecting system in the outermost row, cleaning the collapse invasion limit surrounding rocks in the same row range in the tunnel to the tunnel excavation contour line, and installing the permanent active supporting and protecting system; then, constructing a row of drill holes at the other end of the tunnel in the depth direction, and installing a temporary active supporting and protecting system; and (3) removing one row of temporary active supporting and protecting systems according to the tunnel portal, and installing one row of temporary active supporting and protecting systems at the other end inside the tunnel in a row-by-row construction sequence until all collapse invasion surrounding rock areas are all provided with permanent active supporting and protecting systems.

On the basis, when the lithology in front of the tunnel is unchanged after the collapse invasion limit section is treated, or the tunnel section which generates surrounding rock invasion limit deformation is not treated, the method comprises the following steps:

(1) arranging boreholes in a drilling construction space

Uniformly arranging drill holes in the circumferential direction of the drilling construction space in the direction perpendicular to the depth direction of the tunnel, wherein the drill holes sequentially penetrate through the drilling construction space, the tunnel excavation contour line, the disturbed loose surrounding rock and the undisturbed surrounding rock to form a radial shape; meanwhile, the drill holes are uniformly distributed in a row in the same circumferential section; the holes are arranged in a plurality of rows along the depth direction of the tunnel, and the row spacing of the two adjacent rows of holes is the same as that of the primary support steel arch frame designed for the tunnel; the drilling hole comprises a probing hole and a grouting hole, wherein the probing hole is used for probing the thickness of collapse invasion surrounding rock and the thickness and the depth of disturbance loose surrounding rock;

(2) establishing permanent active supporting and protecting system

Inserting the connected tensile sleeve into a drill hole, grouting, forming a grouting consolidation body between the tensile sleeve and the wall of the drill hole, forming grouting sealing solid after the disturbance loose surrounding rock is formed by grouting, and consolidating the grouting consolidation body, the grouting sealing solid and the undisturbed surrounding rock; the tensile sleeve is provided with a weldable sleeve joint at one end of the tunnel excavation contour line; then laying a permanent protective net on the inner surface of the surrounding rock at the tunnel excavation contour line, installing a permanent steel arch, fixedly connecting the permanent steel arch with the weldable casing joint, and spraying permanent grout on the surface of the permanent protective net; two adjacent rows of permanent steel arch frames are connected through reinforcing steel bars.

The method converts the passive treatment of the geological disasters of invasion limit and collapse caused by artificial disturbance in the tunnel excavation process into an active support system formed by the tensile sleeve and the steel arch frame connected with the tensile sleeve, has simple structure, convenient construction and high efficiency, and effectively realizes the integral reinforcement stability of the surrounding rock section easy to collapse of the tunnel.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

fig. 1 is a schematic front structural view of a temporary active supporting and protecting structure according to the present invention;

FIG. 2 is a schematic bottom view of the temporary active supporting structure of the present invention;

fig. 3 is a schematic side view of the temporary active supporting and protecting structure according to the present invention (the drilling hole is perpendicular to the depth direction of the tunnel);

fig. 4 is a schematic side view of the temporary active supporting and protecting structure according to the present invention (the drilling hole is not perpendicular to the depth direction of the tunnel);

FIG. 5 is a schematic view of a drilling structure of the temporary active supporting and protecting structure according to the present invention;

FIG. 6 is an enlarged view of a portion A of the present invention;

FIG. 7 is a schematic front view of the permanent active bracing reinforcement structure of the present invention;

FIG. 8 is a schematic bottom view of the permanent active bracing reinforcement structure of the present invention;

FIG. 9 is a schematic view of a borehole structure of the medium permanent active support of the present invention;

FIG. 10 is a partial enlarged view of B of the present invention;

FIG. 11 is a schematic structural diagram illustrating the replacement of a temporary active supporting and protecting system with a permanent active supporting and protecting system according to the present invention;

fig. 12 is a schematic structural view of the active supporting and protecting system directly built in the present invention.

Detailed Description

Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

Example 1

As shown in fig. 1 and 8-11, an active supporting and protecting structure for invasion limit deformation of surrounding rocks after tunnel excavation supporting comprises a permanent steel arch 10-2 and a permanent protective net 11-2, and permanent slurry 12-2 is sprayed on the surface of the permanent protective net 11-2;

in addition, in a drilling construction space 15 perpendicular to the depth direction of the tunnel, drill holes 1 which are radially and uniformly distributed are arranged along the directions of collapse invasion limit surrounding rocks 4, tunnel excavation contour lines 5, disturbance loose surrounding rocks 3 and undisturbed surrounding rocks 2, one end of each drill hole 1 is inserted into a tensile sleeve 7 for grouting fixation, and the other end of each drill hole is fixedly connected with a weldable sleeve joint 13.

The drill holes 1 are uniformly distributed in a row in the same annular cross section perpendicular to the depth direction of the tunnel and arranged in multiple rows along the depth direction of the tunnel, and the row spacing of the two adjacent rows of drill holes 1 is the same as that of the primary support steel arch frame in the tunnel design.

The borehole 1 includes a exploration hole 1-1 for exploring the thickness of collapse limiting surrounding rock 4 and the thickness and depth of disturbance loose surrounding rock 3 and a grouting hole 1-2 for installing a casing.

As shown in fig. 2, a temporary supporting and protecting structure is built before an active supporting and protecting structure for a tunnel with surrounding rock limited invasion and deformation, the temporary supporting and protecting structure comprises a temporary steel arch frame 10-1 and a temporary protective net 11-1, and temporary slurry 12-1 is sprayed on the surface of the temporary protective net 11-1; meanwhile, a tensile sleeve 7 for grouting fixation is inserted into one end of the drill hole 1, and a detachable short sleeve 9 is fixedly connected to the other end of the drill hole.

Preferably, the hole spacing a between two adjacent holes of the same row of drill holes 1 near the inner surface of the tunnel is 1-1.5 m.

Preferably, in the drill hole 1 with the same cross section perpendicular to the depth direction of the tunnel, the number ratio of the probing holes 1-1 to the grouting holes 1-2 is 1: 2; the exploration hole 1-1 can be used as a grouting hole 1-2 after the exploration purpose is achieved.

Preferably, the depth d of the grouting bore 1-2 into the undisturbed surrounding rock 2₁Greater than or equal to in disturbed pine3 thickness d of surrounding rock₂2 times of the total weight of the powder.

Preferably, the end of the weldable casing pipe joint 13 connected to the tensile casing pipe 7 is arranged at a distance of 30cm from the tunnel excavation contour line 5 of the disturbed loose surrounding rock 3.

Example 2

As shown in fig. 1-11, an active supporting method for invasion-limited deformation of surrounding rock after tunnel excavation supporting comprises the following steps:

(1) reinforcing and supporting surrounding rock with collapse and invasion limit

As shown in fig. 1 and 2, a deformed steel arch existing at a collapse invasion limiting surrounding rock 4 is reinforced and supported, then a tunnel space is cleaned for a newly added temporary steel arch 10-1, a temporary protective net 11-1 is laid at one end of the temporary steel arch 10-1 supporting the inner wall of the tunnel, and temporary slurry 12-1 is sprayed on the surface of the temporary protective net 11-1;

(2) arranging boreholes in a drilling construction space

As shown in fig. 1, drill holes 1 are uniformly arranged in the circumferential direction of a drilling construction space 15 in the direction perpendicular to the depth direction of the tunnel, and the drill holes 1 sequentially penetrate through the drilling construction space 15, collapse invasion limiting surrounding rocks 4, tunnel excavation contour lines 5, disturbed loose surrounding rocks 3 and undisturbed surrounding rocks 2 in a radial shape;

meanwhile, referring to fig. 2, the drill holes 1 are uniformly distributed in a row in the same circumferential section, the hole distance a between two adjacent holes of the same row of drill holes 1 close to the inner surface of the tunnel is 1-1.5m, and the hole distance e of the section of the drill hole 1 penetrating into the surrounding rock is determined according to the number of the drill holes 1 in the same row and the peripheral length of the cross section at which the point is uniformly distributed;

the holes are arranged in a plurality of rows along the depth direction of the tunnel, and the row spacing b of two adjacent rows of the drill holes 1 is the same as the row spacing of the primary support steel arch frames of the tunnel design;

specifically, as shown in fig. 3 and 4, the drill hole 1 may be formed perpendicular to the depth direction of the tunnel, or may form a certain included angle with the depth direction of the tunnel, and the specific scheme for forming the drill hole 1 may be determined according to the field geological condition.

The drill hole 1 is provided with a probing hole 1-1 for probing the thickness of collapse invasion surrounding rock 4 and the thickness and the depth of disturbance loose surrounding rock 3 and a grouting hole 1-2 for installing a casing;

in a drill hole 1 with the same cross section perpendicular to the depth direction of the tunnel, the number ratio of a probing hole 1-1 to a grouting hole 1-2 is 1: 2;

depth d of grouting drill hole 1-2 into undisturbed surrounding rock 2₁Greater than or equal to the thickness d of the disturbed loose surrounding rock 3₂2 times of the total weight of the powder.

(3) Establishing temporary active supporting and protecting system

As shown in fig. 5 and 6, the temporary active supporting and protecting system includes a tensile sleeve 7 and a detachable short sleeve 9, the tensile sleeve 7 is detachably connected with the detachable short sleeve 9, preferably, in this embodiment, the tensile sleeve 7 and the detachable short sleeve 9 are connected by screw threads, and one end of the detachable short sleeve 9 connected with the tensile sleeve 7 is arranged at a position 30cm away from the tunnel excavation contour line 5 of the disturbed loose surrounding rock 3;

inserting the connected tensile sleeve 7 and the detachable short sleeve 9 into the borehole 1, grouting, forming a grouting consolidation body 6 between the tensile sleeve 7 and the wall of the borehole 1, forming a grouting sealing solid 8 after the disturbance loose surrounding rock 3 is formed by grouting, and consolidating the grouting consolidation body 6, the grouting sealing solid 8 and the undisturbed surrounding rock 2;

(4) establishing permanent active supporting and protecting system

As shown in fig. 7-10, after the detachable short sleeve 9, the temporary steel arch 10-1 and the temporary protective net 11-1 of the temporary active supporting and protecting system are removed, the collapse invasion surrounding rock 4 in the tunnel is cleaned to the tunnel excavation contour line 5, then a permanent protective net 11-2 and a permanent steel arch 10-2 are laid on the inner surface of the tunnel drilling construction space 15, permanent grout 12-2 is sprayed on the surface of the permanent protection net 11-2, and a weldable casing joint 13 is installed at the position of the detachable short casing 9, specifically, one end of the permanent steel arch frame 10-2, which is in contact with the inner wall of the tunnel, is used for supporting the permanent protective net 11-2, so that the permanent protective net 11-2 can be tightly attached to the inner wall of the tunnel, one end of the weldable sleeve joint 13 connected with the tensile sleeve 7 is arranged at a position 30cm away from the tunnel excavation contour line 5 of the disturbed loose surrounding rock 3.

Preferably, two adjacent rows of permanent steel arches 10-2 are connected through the reinforcing steel bars 14, so that the overall protection capability of the safety active supporting and protecting system is improved.

As shown in fig. 11, when the drilling construction space 15 is large, the construction of a plurality of rows of the drilled holes 1 should be completed at one time: after the construction of the row of grouting drill holes 1 is completed, a row of temporary active supporting and protecting systems are installed until all the temporary active supporting and protecting systems are installed, then the temporary active supporting and protecting systems are removed row by row from the tunnel portal to the tunnel along the depth direction of the tunnel, and after the collapse invasion limit surrounding rocks 4 in the same row range in the tunnel are cleaned to the tunnel excavation contour line 5, the permanent active supporting and protecting systems in the same row are installed; and gradually advancing the rows one by one until the permanent safe active supporting and protecting system is completely finished.

When the drilling construction space 15 is small, firstly constructing three rows of drill holes 1 from the hole opening to the hole along the depth direction of the tunnel, wherein the advancing distance of each row is 1.5m, and completely installing temporary active supporting and protecting systems; then, disassembling the temporary active supporting and protecting system in the outermost row, cleaning the collapse invasion limit surrounding rocks 4 in the same row range in the tunnel to a tunnel excavation contour line 5, and then installing the permanent active supporting and protecting system; then, constructing a row of drill holes 1 at the other end of the tunnel in the depth direction, and installing a temporary active supporting and protecting system; and (3) removing one row of temporary active supporting and protecting systems according to the tunnel portal, and installing one row of temporary active supporting and protecting systems at the other end inside the tunnel in a row-by-row construction sequence until all the collapse invasion limit surrounding rock 4 areas are all provided with permanent active supporting and protecting systems.

Example 3

On the basis of embodiment 2, when the lithology in front of the tunnel is not changed after the collapse invasion limit section is treated, or the tunnel section which generates the surrounding rock invasion limit deformation is treated, referring to fig. 1, 7-11, and combining with fig. 12, it should be noted that the surrounding rock invasion limit deformation does not occur in the present embodiment, and therefore the surrounding rock invasion limit 4 does not collapse, including the following steps:

(1) arranging boreholes in a drilling construction space

The method comprises the following steps that drill holes 1 are uniformly arranged in the circumferential direction of a drilling construction space 15 in the direction perpendicular to the depth direction of a tunnel, and the drill holes 1 sequentially penetrate through the drilling construction space 15, a tunnel excavation contour line 5, a disturbed loose surrounding rock 3 and an undisturbed surrounding rock 2 to form a radial shape;

meanwhile, the drill holes 1 are uniformly distributed in a row in the same circumferential section, the hole distance a between two adjacent holes of the drill holes 1 in the same row close to the inner surface of the tunnel is 1-1.5m, and the hole distance e of the section of the drill hole 1 penetrating into the surrounding rock is determined according to the number of the drill holes 1 in the same row and the peripheral length of the cross section at which the point is uniformly distributed;

the holes are arranged in a plurality of rows along the depth direction of the tunnel, and the row spacing b of two adjacent rows of the drill holes 1 is the same as the row spacing of the primary support steel arch frames of the tunnel design;

the drill hole 1 comprises a probing hole 1-1 for probing the thickness of collapse limiting surrounding rock 4 and the thickness and the depth of disturbance loose surrounding rock 3 and a grouting hole 1-2 for installing a casing;

in a drill hole 1 with the same cross section perpendicular to the depth direction of the tunnel, the number ratio of a probing hole 1-1 to a grouting hole 1-2 is 1: 2;

depth d of grouting drill hole 1-2 into undisturbed surrounding rock 2₁Greater than or equal to the thickness d of the disturbed loose surrounding rock 3₂2 times of the total weight of the powder.

(2) Establishing permanent active supporting and protecting system

And inserting the connected tensile sleeve 7 into the borehole 1, grouting, forming a grouting consolidation body 6 between the tensile sleeve 7 and the wall of the borehole 1, forming a grouting sealing solid 8 after the disturbance loose surrounding rock 3 is formed by grouting, and consolidating the grouting consolidation body 6, the grouting sealing solid 8 and the original surrounding rock 2. The tensile sleeve 7 is provided with a weldable sleeve joint 13 at one end of the tunnel excavation contour line 5; then, a permanent protective net 11-2 is laid on the inner surface of the surrounding rock at the tunnel excavation contour line 5, a permanent steel arch 10-2 is installed, the permanent steel arch 10-2 is fixedly connected with the weldable casing joint 13, permanent spraying slurry 12-2 is sprayed on the surface of the permanent protective net 11-2, and one end, in contact with the inner wall of the tunnel, of the permanent steel arch 10-2 is used for supporting the permanent protective net 11-2, so that the permanent protective net 11-2 can be tightly attached to the inner wall of the tunnel.

Preferably, the end of the weldable casing pipe joint 13 connected to the tensile casing pipe 7 is arranged at a distance of 30cm from the tunnel excavation contour line 5 of the disturbed loose surrounding rock 3.

Preferably, two adjacent rows of permanent steel arches 10-2 are connected through the reinforcing steel bars 14, so that the overall protection capability of the safety active supporting and protecting system is improved.

Comparative application

A construction method for actively supporting collapse-prone surrounding rocks of a tunnel is characterized in that under the condition that the method in embodiment 2 is not changed, tunnel construction of a certain tunnel of a Sichuan WM expressway in a stratum with a shale and phyllite interbed corroded by underground water is carried out.

In the section, 37 rows of grouting drill holes are formed behind the tunnel face of the inlet right hole of the tunnel collapse section, 17 drill holes are formed in each row, 37 active supporting systems are installed, and the treatment of collapse intrusion areas is completed; in addition, an active supporting and protecting system is installed at the front end of the tunnel collapse section, and the phenomenon of collapse and limit intrusion of the tunnel is avoided.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.