Underwater anchor cable construction method

Abstract

The present invention provides an underwater anchor cable construction method, which relates to the field of anchor cable construction technology and includes the following steps: drilling and staking out a hole; installing a first section of casing and multiple sections of casing, and drilling a hole; drilling to a depth exceeding the set hole depth of the first section of casing; pulling out the anchor cable drill rod, withdrawing and injecting chemical slurry, and gradually forming a plugging body at the bottom of the hole and in the first section of casing and multiple sections of casing; drilling the hole using an anchor cable drill rig, cleaning the plugging body in the multiple sections of casing, and stopping when drilling reaches the designed hole depth; lowering the anchor cable, free section anchor cable protective sleeve, isolation and centering bracket, primary grouting pipe, and secondary grouting pipe; primary grouting to form an anchor cable grouting body; pulling out the multiple sections of casing section by section, performing secondary grouting once each section of casing is pulled out; inserting a water-swelling wooden plug into the lower end of the hole opening of the ground-connected wall to seal it; sealing the hole opening to form a cavity grouting body behind the wall; and completing the hole. The present invention ensures the stability of the anchor cable hole in underwater sand and gravel formations and prevents fine sand emerging from the bottom of the hole from clogging the casing.

Description

Technical Field

[0001] The present invention relates to the technical field of anchor cable construction, and in particular to an underwater anchor cable construction method. Background Art

[0002] With the development of production and the expansion of urban construction, high-rise buildings, large buildings and various underground facilities are increasing, and more and more deep foundation pit projects are bound to appear. During the construction of deep foundation pit projects, the "ground-connected wall + anchor cable" method is often used for support.

[0003] The construction of anchor cables has high requirements for the stratum. The hole wall is prone to collapse when drilling in sand and gravel strata, especially when there is abundant groundwater in the soil layer. As the groundwater continues to gush out during the drilling process, a large amount of particles in the soil layer are lost, resulting in excessive settlement and deformation behind the pit, affecting the safety of surrounding buildings and facilities.

[0004] For formations with high sand content, when using the casing method for construction, due to the high water pressure at the end of the drill pipe, water and sand will gush out after drilling to the designed depth. The gushing sand will block the casing, making it impossible to place the anchor cable in place.

[0005] When forced to adopt the "ground-anchored wall + internal support" support form, compared with the "ground-anchored wall + anchor cable" support form, its construction cost is high, the construction period is long, and the pollution to the city is serious. Therefore, realizing underwater anchor cable construction can greatly reduce construction costs and shorten construction period. Summary of the Invention

[0006] In order to solve the above problems, the purpose of the present invention is to propose an underwater anchor cable construction method, which can ensure the stability of the anchor cable in the underwater sand and gravel formation, prevent the fine sand gushing out from the bottom of the hole from clogging the casing, and achieve effective sealing of the hole.

[0007] In order to achieve the above technical objectives, the present invention provides an underwater anchor cable construction method, comprising the following steps:

[0008] S1. Determine the anchor hole positions on the ground-connected wall (1) and number the anchor hole positions;

[0009] S2, the anchor cable drilling rig includes an anchor cable drill rod (18), a first section of casing (2) and multiple sections of casing (5) other than the first section of casing (2) are connected, the anchor cable drill rod (18) is inserted into the first section of casing (2) and multiple sections of casing (5) other than the first section of casing (2), and the anchor cable drill rig is used to drill holes at the determined anchor cable opening positions on the ground-connected wall (1);

[0010] S3, when the anchor drilling rig drills a hole deeper than the length of the first section of casing (2), it stops;

[0011] S4, pulling out the anchor drill rod (18) of the anchor drill rig, gradually retreating to inject chemical slurry into the first section casing (2) and the multi-section casing (5), and gradually forming a plugging body (4) in the first section casing (2) and the multi-section casing (5);

[0012] S5, using the anchor drill again to continue drilling the hole in step S3, using the anchor drill to clean the blocking body (4) in the multi-section casing (5), and stopping when the anchor drill reaches the set hole depth;

[0013] S6, pulling out the anchor cable drill rod (18), and inserting the prepared anchor cable, anchor cable protective sleeve (8), isolation centering bracket (9), primary grouting pipe (20) and secondary grouting pipe (21) into the multi-section casing (5);

[0014] S7, injecting cement slurry from bottom to top through the primary grouting pipe (20) to form an anchor grouting body (10);

[0015] S8, after the cement slurry is initially set or the cement slurry is balanced with the water pressure, the multiple sections of casing (5) are pulled out section by section, and during this period, secondary grouting is performed once through the secondary grouting pipe (21) each time a section of casing is pulled out;

[0016] S9, inserting a water-swelling wooden plug (11) into the lower end of the hole of the ground-connected wall (1), then adding a quick-setting and quick-hardening material into the hole of the ground-connected wall (1) to form a plugging body (12), and sealing the water-swelling wooden plug (11);

[0017] S10, a grouting pipe (13) and an exhaust pipe (14) are arranged on the water-swelling wooden plug (11), cement slurry is injected through the grouting pipe (13) and the exhaust pipe (14) and air is exhausted, and the orifice is further sealed to form a grouting body (15) in the cavity behind the wall;

[0018] S11, final hole.

[0019] Preferably, the first section of casing (2) in step S2 is a disposable casing.

[0020] Preferably, the chemical slurry in step S4 includes phosphoric acid and water glass, and pressure grouting is used when injecting the chemical slurry.

[0021] Preferably, in step S6, the isolation and centering bracket (9) is disc-shaped, a plurality of arc-shaped slots are evenly opened on the outer circle of the isolation and centering bracket (9), and two circular through holes are symmetrically opened inside the isolation and centering bracket (9).

[0022] Preferably, a primary grouting pipe (20) and a secondary grouting pipe (21) are respectively provided in the two circular through holes of the isolation and centering bracket (9).

[0023] Preferably, the cement slurry in step S7 is a double slurry, which is a cement-water glass slurry. The cement-water glass slurry uses cement and water glass as main agents, and the cement and water glass are injected in a double liquid manner according to a set ratio, and an additive is added to form a grouting liquid material.

[0024] Preferably, an accelerating setting agent and a retarding setting agent are added to the cement slurry.

[0025] Preferably, the secondary grouting in step S8 adopts pressure grouting.

[0026] Preferably, the water-swellable wooden plug (11) in step S9 is provided with an anchor cable through hole, an exhaust pipe (14) hole, a primary grouting pipe (20) hole, a secondary grouting pipe (21) hole, and a grouting pipe (13) hole.

[0027] Preferably, a zigzag connection (3) is adopted between the first-section sleeve (2) and the multi-section sleeve (5), and the first-section sleeve (2) and the multi-section sleeve (5) are tightly connected by being squeezed against each other.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The disposable first section casing is used to ensure that the inside of the casing is sealed when the anchor cable is lowered, avoiding the backflow of groundwater and medium and fine sand, and ensuring that the anchor cable is lowered in place.

[0030] 2. Injecting cement slurry through the grouting pipe and exhaust pipe at the hole to form the cavity grouting body behind the wall can effectively prevent groundwater and medium and fine sand from gushing out of the hole and affecting the construction.

[0031] 3. By adopting the above construction method, the problem of drilling holes in underwater anchor cable construction is effectively solved, ensuring sufficient bearing capacity of the anchor cable.

[0032] 4. When the foundation pit excavation is below the water level, the above-mentioned construction method is adopted to realize the "ground-connected wall + anchor cable" support of the foundation pit. Compared with the "ground-connected wall + internal support" support form, it can greatly reduce the construction cost and shorten the construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 This is a flow chart of the underwater anchor cable construction method described in the present invention;

[0035] Figure 2 Schematic diagram of the overall structure of the underwater anchor cable construction device of the present invention;

[0036] Figure 3 For the present invention Figure 2 Schematic diagram of the AA section structure;

[0037] Figure 4 For the present invention Figure 2 Schematic diagram of the BB cross-section structure;

[0038] Figure 5 Schematic diagram of steps S1 and S2 of the underwater anchor cable construction method of the present invention;

[0039] Figure 6 Schematic diagram of step S3 of the underwater anchor cable construction method of the present invention;

[0040] Figure 7 Schematic diagram of step S4 of the underwater anchor cable construction method of the present invention;

[0041] Figure 8 Schematic diagram of step S5 of the underwater anchor cable construction method of the present invention;

[0042] Figure 9 Schematic diagram of step S6 of the underwater anchor cable construction method of the present invention;

[0043] Figure 10 Schematic diagram of step S7 of the underwater anchor cable construction method of the present invention;

[0044] Figure 11 Schematic diagram of step S8 and subsequent steps of the underwater anchor cable construction method of the present invention.

[0045] In the figure: 1. Ground-anchored wall; 2. First section of casing; 3. Saw-shaped connection; 4. Sealing body; 5. Multi-section casing; 6. Free section anchor cable; 7. Anchor cable of anchor section; 8. Anchor cable protective cover; 9. Isolation and centering bracket; 10. Anchor cable grouting body; 11. Water-swelling wooden plug; 12. Leakage plug; 13. Grouting pipe; 14. Exhaust pipe; 15. Grouting body for cavity behind wall; 16. Pedestal; 17. Anchor; 18. Anchor cable drill rod; 19. Drill bit; 20. Primary grouting pipe; 21. Secondary grouting pipe. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0047] The following is combined with Figure 1-11 This application is described in further detail.

[0048] Reference Figure 1 The present invention proposes an underwater anchor cable construction method, which installs a disposable first-section casing 2 and multiple-section casings 5 except the first-section casing 2, and adopts a casing follow-up drilling method. The anchor cable drill stops when it drills to a length of the disposable first-section casing 2 that exceeds the designed hole depth. When the anchor cable drill rod 18 is pulled out, the chemical slurry is gradually withdrawn to inject a water-stopping plugging body 4, and the anchor cable drill is used again to drill a hole, and the plugging body 4 in the multiple-section casing 5 is cleaned. Since the plugging body 4 in the first-section casing 2 still exists, the inside of the casing is in a sealed state at this time, which can ensure that the subsequent free-section anchor cable 6 and the anchoring-section anchor cable 7 are placed in place; the anchor cable grouting body 10 is formed by primary grouting and secondary grouting, and after the grouting is completed, the hole mouth is further sealed 12 and the cavity behind the wall is grouted 15, and then the hole is completed.

[0049] Reference Figure 2 The first section casing 2 and the multi-section casing 5 are obliquely drilled into the ground-connected wall 1. An anchor cable is provided at the center of the multi-section casing 5, and a water-expanding wooden plug 11 is provided at the hole mouth. The first section casing 2 is connected to the multi-section casing 5 through a zigzag connection 3. There is a blocking body 4 in the first section casing 2 to block the bottom of the hole and the inside of the multi-section casing 5. The blocking body 4 is a phosphoric acid-water glass chemical slurry that solidifies quickly when it meets water. The anchor cable is divided into a free section anchor cable 6 and an anchor section anchor cable 7, which is supported by an isolation pair. The frame 9 is positioned; the water-swelling wooden plug 11 is provided with an anchor cable through hole, an exhaust pipe 14 hole, a primary grouting pipe 20 hole, a secondary grouting pipe 21 hole and a grouting pipe 13 hole, and a quick-setting and quick-hardening material is added to the hole of the ground-connected wall to form a plugging body 12, and the water-swelling wooden plug 11 is sealed to preliminarily seal the hole. Cement slurry is injected through the grouting pipe 13 and the exhaust pipe 14 and the air is discharged to form a grouting body 15 for the cavity behind the wall, and the hole is further sealed.

[0050] Reference Figure 3The isolation and centering bracket 9 is disc-shaped. The isolation and centering bracket 9 is arranged at a certain interval. There are several arc-shaped slots on the outer circle and two round through holes inside. The slots play the role of isolating the anchor cables. Together with the anchor cable protective sleeve 8, they can ensure that the free section anchor cable 6 does not move; the two round through holes are used to set the primary grouting pipe 20 and the secondary grouting pipe 21 respectively; the anchor cable protective sleeve 8 can ensure that the free section anchor cable 6 is in a free state.

[0051] Reference Figure 4 The anchor cable 7 of the anchoring section is positioned by the isolation centering bracket 9 and is located in the rear section of the multi-section casing 5. No anchor cable protective sleeve 8 is provided for the later fixation of the anchor cable and the soil layer.

[0052] Reference Figure 3 、 Figure 4 There is an anchor grouting body 10 between the free section anchor cable 6, the anchor section anchor cable 7 and the soil layer. After the anchor grouting body solidifies, the free section anchor cable 6 and the anchor section anchor cable 7 can be stably fixed in the drilled hole of the soil layer, and can withstand a large horizontal displacement of the ground-connected wall 1; the cement slurry of the anchor grouting body 10 adopts cement-water glass slurry, which overcomes the shortcomings of single-liquid cement slurry such as long coagulation time and difficulty in control, and low stone rate under dynamic water conditions, improves the effect of cement grouting, and expands the scope of application of cement grouting.

[0053] Example: This application example discloses a method for constructing an underwater anchor cable:

[0054] Reference Figure 5 S1. According to the design layout requirements and the on-site conditions, the anchor hole positions are accurately measured and placed on the ground-connected wall 1, and the anchor cable opening positions are indicated. The anchor hole positions that have been measured and accepted are numbered, and the numbers are used as the basis for the anchor cable production numbers;

[0055] S2, install the disposable first section casing 2 and multiple sections of casing 5 except the first section casing 2, and use the anchor drilling rig to drill the holes using the casing follow-up process;

[0056] refer to Figure 6 , S3, when the anchor drill rig drills to the designed hole depth, continue drilling forward until the drilling reaches a length exceeding the designed hole depth and the first section of the disposable casing 2 is stopped;

[0057] refer to Figure 7 , S4, pull out the anchor drill rod 18, gradually retreat and inject chemical slurry, and gradually form a plugging body 4 at the bottom of the hole, the first section casing 2 and the multi-section casing 5;

[0058] refer to Figure 8 , S5, use the anchor drill to drill again, use the anchor drill to clean the plugging body 4 in the multi-section casing 5, and stop when the anchor drill reaches the designed hole depth;

[0059] refer to Figure 9 , S6, pull out the anchor drill rod 18, insert the prepared anchor cable, anchor cable protective cover 8, isolation centering bracket 9, primary grouting pipe 20 and secondary grouting pipe 21 into the multi-section casing 5;

[0060] refer to Figure 10 , S7, injecting cement slurry from bottom to top through the primary grouting pipe 20 to form an anchor grouting body 10;

[0061] refer to Figure 11 S8, after the cement slurry is initially set or the cement slurry is balanced with the water pressure, the multi-section casing 5 is pulled out section by section, and each time a multi-section casing 5 is pulled out, secondary grouting is performed once through the secondary grouting pipe 21;

[0062] S9. Use a water-swelling wooden plug 11 to plug the lower end of the hole of the ground-connected wall 1, and then add a quick-setting and fast-hardening material into the hole of the ground-connected wall 1 to form a plug 12 to seal the water-swelling wooden plug 11;

[0063] S10, the grouting pipe 13 and the exhaust pipe 14 are set on the water-swelling wooden plug 11, and cement slurry is injected through the grouting pipe 13 and the exhaust pipe 14 and the air is exhausted, further sealing the hole to form a grouting body 15 in the cavity behind the wall;

[0064] S11, final hole.

[0065] In some preferred embodiments, the first section of casing 2 in S2 is disposable. The first section of casing 2 is gradually withdrawn and chemical slurry is injected to seal the interior of the multi-section casing 5, thereby enhancing the sealing of the bottom of the hole.

[0066] In some preferred embodiments, the chemical slurry in S4 includes phosphoric acid and water glass. The chemical slurry quickly condenses when it comes into contact with water, and combines with the mud and sand in the first section casing 2 and the multi-section casing 5 to form a sealing body 4. The anchor drill rig is used for drilling again to clean up all the mud and sand that have flowed into the multi-section casing 5, making it easier to lower the anchor cable later.

[0067] In some preferred embodiments, the isolation centering bracket 9 in S6 is disc-shaped, and a number of arc-shaped slots are evenly opened on the outer circle of the isolation centering bracket 9. Two circular through holes are symmetrically opened inside the isolation centering bracket 9. A primary grouting pipe 20 and a secondary grouting pipe 21 are respectively provided in the two circular through holes of the isolation centering bracket 9, which provide convenience for subsequent anchor grouting.

[0068] In some preferred embodiments, the cement slurry in S7 is a double slurry, using cement-water glass slurry, which is a grouting liquid material composed of cement and water glass as the main agents, and the two are injected in a double liquid manner in a certain proportion, and additives are added when necessary. The ratio of cement to water glass is 1:0.05. The cement slurry uses cement-water glass slurry. This slurry overcomes the shortcomings of single-liquid cement slurry, such as long coagulation time and difficulty in control, and low stone rate under dynamic water conditions, improves the effect of cement grouting, and expands the scope of application of cement grouting.

[0069] In some preferred embodiments, the water-cement ratio in the cement slurry is 0.5:1. Accelerator and retarder are added to the cement slurry. Using an appropriate water-cement ratio can ensure the workability of concrete while ensuring the strength of concrete. Adding the accelerator to the cement slurry can make the concrete set and harden quickly. The retarder can reduce the hydration heat peak, prolong the hydration exothermic time, and improve the workability of concrete. The accelerator and retarder complement each other and can expand the scope of application of the cement slurry.

[0070] In some preferred embodiments, in S8, the multi-section casing 5 is pulled out section by section when the cement slurry is initially set or the cement slurry is balanced with the water pressure, thereby avoiding the diffusion of the slurry. During the period of pulling out the multi-section casing 5 section by section, secondary grouting is performed once to ensure the fullness of the grouting. The secondary grouting adopts pressure grouting.

[0071] In some preferred embodiments, the water-swelling wooden plug 11 in S9 is provided with an anchor cable through hole, an exhaust pipe 14 hole, a primary grouting pipe 20 hole, a secondary grouting pipe 21 hole and a grouting pipe 13 hole. A quick-setting and quick-hardening material is added to the hole of the ground-connected wall to form a plugging body 12, and the water-swelling wooden plug 11 is sealed to preliminarily seal the hole. Cement slurry is injected through the grouting pipe 13 and the exhaust pipe 14 and the air is discharged to form a cavity grouting body 15 behind the wall, and the hole is further sealed, which can effectively prevent groundwater and fine sand from gushing out of the hole.

[0072] In some preferred embodiments, a zigzag connection 3 is adopted between the first section casing 2 and the multi-section casing 5. When the casing follows the drilling, the first section casing 2 and the multi-section casing 5 are squeezed and tightly connected with each other. When the multi-section casing 5 is pulled out section by section, the first section casing 2 and the multi-section casing 5 can be easily disengaged, and the first section casing 2 remains in the hole to ensure the sealing of the bottom of the hole.

[0073] In some preferred embodiments, a 25 mm thick steel plate is laid under the anchor drilling rig to prevent it from sinking and tilting, thereby ensuring that the anchor drilling rig can work stably.

[0074] It should be noted that similar numbers and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and are not to be understood as indicating or implying relative importance.

[0075] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the above-described embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above-described embodiments within the technical scope disclosed by the present invention, or replace some of the technical features therein with equivalents. However, such modifications, changes, or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. They should all be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. An underwater anchor cable construction method, characterized in that: The following steps are involved: S1. Determine the anchor hole positions on the ground-connected wall (1) and number the anchor hole positions; S2, an anchor cable drilling rig includes an anchor cable drill rod (18), a first section casing (2) and multiple sections casing (5) other than the first section casing (2) are connected, the anchor cable drill rod (18) is inserted into the first section casing (2) and multiple sections casing (5) other than the first section casing (2), and the anchor cable drilling rig is used to drill holes at the determined anchor cable opening positions on the ground-connected wall (1), the first section casing (2) and the multiple sections casing (5) are connected by a sawtooth shape (3), and the first section casing (2) and the multiple sections casing (5) are squeezed and tightly connected to each other; S3, when the anchor drilling rig drills a hole deeper than the length of the first section of casing (2), it stops; S4, pulling out the anchor drill rod (18) of the anchor drill rig, gradually retreating to inject chemical slurry into the first section casing (2) and the multi-section casing (5), and gradually forming a plugging body (4) in the first section casing (2) and the multi-section casing (5); S5, using the anchor drill again to continue drilling the hole in step S3, using the anchor drill to clean the blocking body (4) in the multi-section casing (5), and stopping when the anchor drill reaches the set hole depth; S6, pulling out the anchor cable drill rod (18), and inserting the prepared anchor cable, anchor cable protective sleeve (8), isolation centering bracket (9), primary grouting pipe (20) and secondary grouting pipe (21) into the multi-section casing (5); S7, injecting cement slurry from bottom to top through the primary grouting pipe (20) to form an anchor grouting body (10); S8, after the cement slurry is initially set or the cement slurry is balanced with the water pressure, the multiple sections of casing (5) are pulled out section by section, and during this period, secondary grouting is performed once through the secondary grouting pipe (21) each time a section of casing is pulled out; S9, inserting a water-swelling wooden plug (11) into the lower end of the hole of the ground-connected wall (1), then adding a quick-setting and quick-hardening material into the hole of the ground-connected wall (1) to form a plugging body (12), and sealing the water-swelling wooden plug (11); S10, a grouting pipe (13) and an exhaust pipe (14) are arranged on the water-swelling wooden plug (11), cement slurry is injected through the grouting pipe (13) and the exhaust pipe (14) and air is exhausted, and the orifice is further sealed to form a grouting body (15) in the cavity behind the wall; S11, final hole.

2. The underwater anchor cable construction method according to claim 1, characterized in that: The first section of casing (2) in step S2 is a disposable casing.

3. The underwater anchor cable construction method according to claim 1, characterized in that: The chemical slurry in step S4 includes phosphoric acid and water glass, and pressure grouting is used when injecting the chemical slurry.

4. The underwater anchor cable construction method according to claim 1, characterized in that: In step S6, the isolation and centering bracket (9) is in the shape of a disc, and a plurality of arc-shaped slots are evenly opened on the outer circle of the isolation and centering bracket (9), and two circular through holes are symmetrically opened inside the isolation and centering bracket (9).

5. The underwater anchor cable construction method according to claim 1, characterized in that: A primary grouting pipe (20) and a secondary grouting pipe (21) are respectively provided in the two circular through holes of the isolation and centering bracket (9).

6. The underwater anchor cable construction method according to claim 1, characterized in that: In step S7, the cement slurry is a double slurry, which is a cement-water glass slurry. The cement-water glass slurry uses cement and water glass as main agents. The cement and water glass are injected in a double liquid manner according to a set ratio, and an additive is added to form a grouting liquid material.

7. The underwater anchor cable construction method according to claim 4, characterized in that: Adding an accelerating setting agent and a retarding setting agent into the cement slurry.

8. The underwater anchor cable construction method according to claim 1, characterized in that: The secondary grouting in step S8 adopts pressure grouting.

9. The underwater anchor cable construction method according to claim 1, characterized in that: The water-swellable wooden plug (11) in step S9 is provided with an anchor cable through hole, an exhaust pipe (14) hole, a primary grouting pipe (20) hole, a secondary grouting pipe (21) hole, and a grouting pipe (13) hole.

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