High-toughness foot-lock anchor cable for soft rock large-deformation tunnel and primary support

Abstract

The utility model discloses a high-toughness feet-lock anchor cable for a soft rock large-deformation tunnel and a primary support. The high-toughness feet-lock anchor cable comprises a steel strand, a deformation device and an anchorage device. The deformation device is composed of a steel sleeve and a hollow circular truncated cone, the steel sleeve is arranged on the steel strand in a sleeving mode, the steel sleeve comprises a pipe expanding section, a transition section and an unexpanded pipe section, and the transition section is of a conical cylinder structure and connected between the pipe expanding section and the unexpanded pipe section; the small-diameter end of the hollow circular truncated cone is sleeved with the unexpanded pipe section of the steel sleeve, and the side face of the hollow circular truncated cone is tightly attached to the inner surface of the transition section. The deformation device matched with a conventional feet-lock anchor cable is additionally arranged, the adaptability of the feet-lock anchor cable to deformation of a primary support arch foot is improved through tensile deformation generated by relative sliding between a steel sleeve and a rigid hollow circular truncated cone, and then the overall disaster resistance toughness of a primary support structure of a soft rock large-deformation tunnel is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of tunnel engineering, and particularly relates to a high-toughness locking foot anchor cable and initial support for a soft rock large-deformation tunnel. BACKGROUND

[0002] A soft rock tunnel is usually excavated in sections by using a bench method, and the arch foot is a weak part of the initial support structure, which often causes significant settlement and convergence deformation, aggravating large deformation and even collapse disasters. Based on a large number of studies on the deformation law of a loess tunnel, a high-water-content soil tunnel and other soft rock tunnels and the effect of system anchor rods, the inventor first proposed, in 2007, that the system anchor rods of a soft rock tunnel should be cancelled and locking foot anchor pipes (rods) should be added, creating a tunnel steel frame net spraying locking foot combined structure composed of a "steel frame + steel mesh + sprayed concrete + locking foot anchor pipe (rod)". Compared with the traditional initial support structure form used in tunnel engineering, this structure form has the significant technical advantages of simple structure, strong practicability, convenient and fast construction, good economy, wide application range and the like, and has been widely used in actual engineering. Moreover, the possibility of "cutting corners" of system anchor rods is fundamentally eliminated.

[0003] The early tunnel steel frame net spray lock foot combined structure belongs to full passive support, has good structural reliability, is suitable for the case that the settlement deformation of the initial support arch foot is dominant, and has limited control effect on the horizontal convergence deformation of the initial support arch foot. In view of the need for controlling the horizontal convergence deformation of the initial support arch foot of the soft rock large deformation tunnel, the patent “tunnel lock foot anchor cable and initial support arch foot horizontal convergence deformation control method” CN202210156184.5 discloses a small-diameter prestressed lock foot anchor cable support technology, forms a new generation of tunnel steel frame net spray lock foot combined structure, and is applied in actual engineering. Compared with the traditional lock foot anchor pipe (rod) support, the lock foot anchor cable has the advantages of large anchoring depth, high bearing capacity, and the ability to apply pre-tightening force to realize active support, can control the settlement of the initial support arch foot, and can control the horizontal convergence deformation of the initial support arch foot, simultaneously realizes the active and passive combined support, and effectively makes up for the functional short board of the early tunnel steel frame net spray lock foot combined structure. However, due to the persistence and suddenness of the arch foot deformation of the soft rock large deformation tunnel, especially in the process of subpart excavation, the initial support arch foot is suspended, which will induce rapid deformation of the arch foot, and at the same time means that the original arch foot load will be transferred to the lock foot anchor cable in a short time; when the axial force increment of the lock foot anchor cable is too large or the extension rate is insufficient, the anchoring failure or collapse failure risk of the lock foot anchor cable will be caused. In other words, the existing tunnel steel frame net spray lock foot combined structure has poor adaptability to the arch foot deformation in the process of subpart excavation of the soft rock large deformation tunnel, and shows that the toughness of the tunnel steel frame net spray lock foot combined structure is insufficient due to the insufficient axial extension rate of the lock foot anchor cable. However, if a small pre-tightening force is applied to prevent the lock foot anchor cable from failing due to excessive stress, the active support effect will be significantly reduced. Therefore, it is urgent to develop a soft rock tunnel initial support structure that can adapt to the deformation of the initial support arch foot and provide a constant restraint force to the tunnel arch foot, and improve the disaster resistance and toughness of the soft rock large deformation tunnel initial support structure. Practical new type content

[0004] In view of the above technical problems, the utility model provides a high toughness lock foot anchor cable and initial support suitable for soft rock large deformation tunnel, to prevent the lock foot anchor cable from producing anchoring failure or collapse failure due to insufficient toughness and excessive stress, and further affect the overall stability and safety of the soft rock tunnel initial support structure.

[0005] To achieve the above purpose, the technical scheme adopted by the utility model is as follows:

[0006] A high-toughness locking foot anchor cable for a soft rock large deformation tunnel, comprising a steel strand, a deformation device and an anchor; the deformation device is composed of a steel sleeve and a hollow circular truncated cone, the steel sleeve comprises an expanded tube section, a transition section and an unexpanded tube section, the transition section is a tapered cylinder structure and is connected between the expanded tube section and the unexpanded tube section; the small-diameter end of the hollow circular truncated cone is sleeved in the unexpanded tube section of the steel sleeve, and the side surface of the hollow circular truncated cone is arranged close to the inner surface of the transition section; the steel sleeve is arranged in the sprayed concrete, and the large-diameter end of the hollow circular truncated cone is fixed to the steel strand through the anchor.

[0007] In the high-toughness locking foot anchor cable for a soft rock large deformation tunnel, an external clamping ring is welded to the outer wall of the head of the expanded tube section.

[0008] In the high-toughness locking foot anchor cable for a soft rock large deformation tunnel, the external clamping ring is a hollow circular truncated cone structure, and the top and bottom of the circular truncated cone are connected through an arc surface.

[0009] In the high-toughness locking foot anchor cable for a soft rock large deformation tunnel, an internal clamping ring is welded to the inner wall of the tail of the unexpanded tube section.

[0010] In the high-toughness locking foot anchor cable for a soft rock large deformation tunnel, a longitudinal connecting steel belt and an anchor pad are arranged between the external clamping ring and the outer surface of the sprayed concrete from inside to outside; the longitudinal connecting steel belt integrally connects adjacent extendable locking foot anchor cables.

[0011] In the high-toughness locking foot anchor cable for a soft rock large deformation tunnel, the steel sleeve is made by locally expanding the steel tube with an expanding machine.

[0012] A primary support for a soft rock large deformation tunnel, comprising a steel frame, a steel mesh, a longitudinal connecting rib, a locking foot anchor pipe, sprayed concrete and a high-toughness locking foot anchor cable; the steel mesh is laid behind the steel frame and is welded at the contact position with the steel frame; the locking foot anchor pipe is arranged at the arch foot and wall foot positions and is welded at the end to the steel frame.

[0013] In the primary support for a soft rock large deformation tunnel, a longitudinal connecting steel belt and an anchor pad are arranged between the external clamping ring of the steel sleeve and the outer surface of the sprayed concrete; the longitudinal connecting steel belt integrally connects adjacent high-toughness locking foot anchor cables along the longitudinal direction of the tunnel.

[0014] In the primary support for a soft rock large deformation tunnel, a longitudinal connecting rib is arranged between adjacent steel frames.

[0015] The high-toughness lock foot anchor cable works as follows: the initial support arch foot is constrained by the anchor pad and the steel sleeve in the deformation process, and the constraint is essentially provided by the rigid hollow circular table fixed on the steel strand by the anchor, that is, the rigid hollow circular table and the steel strand anchored in the deep surrounding rock (both can be regarded as a whole) block the displacement of the steel sleeve, the anchor pad, the longitudinal connecting steel belt and the initial support arch foot (the four can be regarded as a whole) in the direction of the tunnel clearance, and thus is subjected to the active load transmitted by the initial support arch foot in the deformation process. When the force transmitted by the initial support arch foot to the steel sleeve is small, the interaction force between the steel sleeve and the rigid hollow circular table is smaller than the designed resistance between the steel sleeve and the rigid hollow circular table, and no relative displacement occurs between the two, only the elastic deformation of the steel strand itself occurs; when the force transmitted by the initial support arch foot to the steel sleeve is large, the interaction force between the steel sleeve and the rigid hollow circular table is equal to the designed resistance between the steel sleeve and the rigid hollow circular table, and the gradual change section and the unexpanded section of the steel sleeve are subjected to the internal supporting force of the rigid hollow circular table and are deformed and relatively displaced with the rigid hollow circular table, and then become part of the new expanded section; with the continuous increase of the deformation of the initial support arch foot, when the steel sleeve slides to the contact of the internal clasp ring sliding with the rigid hollow circular table, the deformation device reaches the maximum sliding amount. The above process uses the relative sliding between the steel sleeve and the rigid hollow circular table to improve the adaptability of the lock foot anchor cable to the deformation of the initial support arch foot, and uses the constant expansion sliding resistance generated in the relative sliding process of the steel sleeve and the rigid hollow circular table to provide a constant constraint force for the initial support arch foot.

[0016] Compared with the prior art, the utility model has the advantages and effects as follows:

[0017] One, the existing tunnel steel frame net spray lock foot combined structure has poor structural toughness in the deformation control of the arch foot of the soft rock large deformation tunnel, mainly manifested as poor adaptability of the lock foot anchor cable to the deformation of the initial support arch foot, because the axial elongation rate of the lock foot anchor cable is generally only about 3%, and the low elongation rate is difficult to adapt to the deformation characteristics (with persistence and suddenness) of the initial support arch foot of the soft rock large deformation tunnel, and there is a risk of anchoring failure or collapse failure. In order to solve such problems, the utility model adds a deformation device matched with the conventional lock foot anchor cable on the basis of the existing tunnel steel frame net spray lock foot combined structure, uses the tensile deformation generated by the relative sliding between the steel sleeve and the rigid hollow circular table to improve the adaptability of the lock foot anchor cable to the deformation of the initial support arch foot, and uses the constant expansion sliding resistance generated in the relative sliding process of the steel sleeve and the rigid hollow circular table in the deformation device to provide a constant constraint force for the initial support arch foot, so as to prevent the lock foot anchor cable from failing due to insufficient elongation, being unable to adapt to the deformation of the initial support arch foot or being subjected to excessive force, and thus improve the overall disaster resistance of the initial support structure of the soft rock large deformation tunnel, realize the combination of resistance and toughness, and achieve high strength and toughness.

[0018] II. Compared with the existing soft surrounding rock tunnel primary support structure system (provided with a large number of systematic anchor rods / anchor cables, 19-25 per ring), the utility model does not set a large number of systematic anchor rods / anchor cables, only adds high-toughness locking anchor cables at the deformation control key position of the tunnel primary support arch foot, and forms a soft rock large deformation tunnel primary support structure which can greatly shorten the tunnel construction period (more than 5 hours of working hours can be saved for each excavation and support construction cycle of the tunnel) and greatly reduce the engineering cost (up to tens of thousands of yuan can be saved for each meter of tunnel construction cost).

[0019] III. The utility model is an important technical innovation of the existing soft surrounding rock tunnel primary support structure system, and has important academic research value and engineering application value. If it is popularized and applied to soft rock large deformation tunnel construction, a large amount of engineering funds can be saved for the country, and the economic and social benefits will be very significant. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a front view of the high-toughness primary support structure for soft rock large deformation tunnel in the embodiment of the utility model;

[0021] Figure 2 is a side view of the high-toughness primary support structure for soft rock large deformation tunnel in the embodiment of the utility model;

[0022] Figure 3 is a schematic view of the steel frame and steel mesh sprayed concrete in the embodiment of the utility model;

[0023] Figure 4 is a schematic view of the high-toughness locking anchor cable in the embodiment of the utility model;

[0024] Figure 5 is a schematic view of the high-toughness locking anchor cable deformation device in the embodiment of the utility model;

[0025] Figure 6 is a schematic view of the high-toughness locking anchor cable elastic deformation stage principle in the embodiment of the utility model;

[0026] Figure 7 is a schematic view of the high-toughness locking anchor cable constant resistance deformation stage principle in the embodiment of the utility model;

[0027] Figure 8 is a schematic view of the high-toughness locking anchor cable limit deformation stage principle in the embodiment of the utility model;

[0028] Fig. 1-steel frame; 2-steel mesh; 3-longitudinal connecting rib; 4-lock foot anchor pipe; 5-sprayed concrete; 6-high toughness lock foot anchor cable; 7-steel strand, 8-deformation device; 9-longitudinal connecting steel strip; 10-anchor pad, 11-anchor device; 12-steel sleeve; 13-rigid hollow circular table; 14-expanded pipe section; 15-gradual change section; 16-unexpanded pipe section; 17-external clasp; 18-internal clasp; 19-anchoring section. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the utility model more clearly, the following will make further detailed description to the utility model by combining with the drawings and examples. It should be understood that the specific examples described here are only used to explain the utility model, and are not used to limit the utility model.

[0030] On the contrary, the utility model covers any substitution, modification, equivalent method and scheme defined by the claims on the essence and scope of the utility model. Further, in order to make the public have a better understanding of the utility model, some specific details are described in the following detailed description of the utility model. The utility model can also be completely understood without the description of these details for those skilled in the art.

[0031] Taking the three-step method of tunnel construction as an example, the specific scheme of the utility model is introduced.

[0032] As shown in Figures 1 to 3 A preliminary support for a large-deformation tunnel in soft rock, comprising a steel frame 1, a steel mesh 2, a longitudinal connecting rib 3, a lock foot anchor pipe 4, sprayed concrete 5 and a high-toughness lock foot anchor cable 6. The steel mesh 2 is laid behind the steel frame 1 and welded at the contact position with the steel frame 1. The lock foot anchor pipe 4 is arranged at the arch foot and wall foot positions during the tunnel subpart excavation process, and the end thereof is welded with the steel frame 1. The high-toughness lock foot anchor cable 6 has the functions of high elongation, high pre-tightening force and constant constraint force for the arch foot, is arranged near the arch foot of the preliminary support with significant deformation, prevents the anchor cable axial force increment from being too large during the tunnel subpart excavation process to cause anchoring failure or collapse failure, and improves the toughness of the tunnel steel frame mesh spray lock foot combined structure.

[0033] As shown in Figure 4 and Figure 5As shown, the high-toughness locking-foot anchor cable 6 is composed of a steel strand 7, a deformation device 8, a longitudinal connecting steel band 9, an anchor pad 10 and an anchor 11; the deformation device 8 is composed of a steel sleeve 12 and a rigid hollow circular truncated cone 13, and is sleeved on the steel strand 7; the steel sleeve 12 is arranged in the shotcrete 5; the rigid hollow circular truncated cone 13 is located inside the steel sleeve 12 and is fixed by the anchor 11 so as not to have relative displacement along the clearance direction of the tunnel; the steel sleeve 12 is composed of an expanded tube section 14, a gradual change section 15 and a non-expanded tube section 16 after being partially expanded by a special expanding machine, the expanded tube section 14 is welded with an external clasp 17 on the outer wall of the head for restraining the displacement of the initial support arch foot, the longitudinal connecting steel band 9 and the anchor pad 10 along the clearance direction of the tunnel, and the non-expanded tube section 16 is welded with an internal clasp 18 on the inner wall of the tail for preventing the relative displacement between the steel sleeve 12 and the rigid hollow circular truncated cone 13 from finally leading to disengagement failure.

[0034] In the embodiment, the specific parameters are as follows: the diameter of the steel strand 7 is 21.8 mm; the anchor pad 10 is square, the side length is 300 mm, the thickness is 18 mm, and the center hole diameter is 110 mm; the anchor 11 is a KM22 type anchor; the rigid hollow circular truncated cone 13 has an upper bottom surface diameter of 60 mm, a lower bottom surface diameter of 70 mm and a center hole diameter of 22 mm; the expanded tube section 14 has an outer diameter of 92 mm, a wall thickness of 11 mm, an initial length of 50 mm, and the internal part of the gradual change section 15 is tangent to the rigid hollow circular truncated cone 13; the non-expanded tube section 16 has an outer diameter of 84 mm, a wall thickness of 12 mm and a length of 300 mm; the external clasp 17 has an outer diameter of 144 mm at the wide part, an outer diameter of 98 mm at the narrow part, a wall thickness of 26 mm, a length of 44 mm and a center hole diameter of 92 mm; the internal clasp 18 has a diameter of 60 mm, a thickness of 12 mm and a center hole diameter of 22 mm.

[0035] As shown in Figs. 6, Figure 7 and Figure 8 After the high-toughness locking-foot anchor cable is installed, it is subjected to the action load transmitted by the initial support arch foot. When the action load of the arch foot is small, the high-toughness locking-foot anchor cable is in the elastic deformation stage. Figure 6 When the action load of the arch foot is greater than or equal to the designed resistance between the steel sleeve and the rigid hollow circular truncated cone, the high-toughness locking-foot anchor cable starts to enter the plastic deformation stage. Figure 7The constant resistance deformation stage in the steel sleeve, which is under the action of the arch foot load, starts to expand and slip towards the rigid hollow circular table, and has the constant resistance characteristic in the process of the steel sleeve slip (which means that the lock foot anchor cable provides constant constraint force for the initial support arch foot), which ensures that the lock foot anchor cable will not be pulled out of function in the working process, and at the same time, the radial expansion and slip deformation of the steel sleeve ensures that the axial deformation of the lock foot anchor cable is within the elastic range; when the steel sleeve slips to the contact between the internal snap ring and the rigid hollow circular table, the deformation device reaches the maximum slip amount, i.e. the maximum elongation, and then if the arch foot deformation further increases, the lock foot anchor cable has already reached the constant resistance function, and then enters the Figure 8 limit deformation stage. The above process is equivalent to improving the elongation rate and allowable deformation capacity of the lock foot anchor cable, i.e. the toughness of the lock foot anchor cable support. Since the deformation device has damping, the extension amount of the anchor cable will not increase unlimitedly under the action of the external force. Since the high-toughness lock foot anchor cable has the functions of high elongation rate, high pre-tightening force and constant constraint force for the arch foot, and is arranged near the initial support arch foot with significant deformation, the lock foot anchor cable can be prevented from being pulled out of function or broken due to the excessive increase of the axial force in the process of the tunnel sub-excavation, and further, the overall disaster resistance and toughness of the initial support structure of the soft rock large-deformation tunnel can be improved.

[0036] The utility model is used for the construction method of the initial support of the soft rock large-deformation tunnel, which comprises the following steps:

[0037] [1] upper step construction: under the advanced support, the tunnel upper step excavation, vertical steel frame welding, longitudinal connecting rib laying, steel mesh laying, lock foot anchor pipe setting, advanced support construction and shotcrete operation are carried out in the current construction cycle, and the cycle is repeated 2-3 times, after the shotcrete forms a certain strength, the construction of the high-toughness lock foot anchor cable at the upper step arch foot is carried out on the shotcrete surface, and the specific construction process flow comprises:

[0038] [1.1] drilling: on the shotcrete surface between every two adjacent steel frames of the initial support arch foot, drilling, hole cleaning and hole expansion of the anchoring hole are carried out by using a drilling machine, and the hole expansion depth is consistent with the length of the deformation device;

[0039] [1.2] anchoring operation and component installation: the resin anchoring agent cartridge is sent into the bottom of the anchoring hole, and the steel strand is inserted into the anchoring hole, the resin anchoring agent is stirred and anchored by the drilling machine and the stirrer, then the longitudinal connecting steel belt, the anchor pad, the deformation device and the anchor are sequentially installed, wherein the deformation device is installed in the anchoring hole after hole expansion, and the longitudinal connecting steel belt, the anchor pad and the anchor are located on the shotcrete surface of the initial support arch foot;

[0040] 【1.3】Pre-tightening force application: After the resin anchoring agent is stirred for 0.5 h, the steel strand is tensioned by using a tensioning tool to complete the pre-tightening force application of the high-toughness locking-anchor cable;

[0041] 【2】Middle step construction: The left side and the right side of the middle step are staggered by 2-3 steel frame intervals, and the middle step is excavated, supported, and sprayed with concrete. After the middle step is excavated, the vertical connecting rib is welded, the steel bar mesh is laid, the locking-anchor pipe is punched, and the concrete is sprayed, the cycle is repeated for 2-3 times. After the sprayed concrete forms a certain strength, the high-toughness locking-anchor cable is constructed at the arch foot of the middle step on the surface of the sprayed concrete. The specific construction process is the same as step 【1】.

[0042] 【3】Lower step construction: The left side and the right side of the lower step are staggered by 2-3 steel frame intervals, and the lower step is excavated, supported, and sprayed with concrete. After the lower step is excavated, the vertical connecting rib is welded, the steel bar mesh is laid, the locking-anchor pipe is punched, and the concrete is sprayed, the cycle is repeated for 2-3 times. After the sprayed concrete forms a certain strength, the high-toughness locking-anchor cable is constructed at the arch foot of the middle step on the surface of the sprayed concrete. The specific construction process is the same as step 【1】.

[0043] 【4】Inverted arch construction: After the inverted arch is excavated, the inverted arch steel frame is constructed, the vertical connecting rib is welded, the steel bar mesh is laid, and the concrete is sprayed, the cycle is repeated for 2-3 times. After the sprayed concrete forms a certain strength, the high-toughness locking-anchor cable is constructed at the arch foot of the middle step on the surface of the sprayed concrete. The specific construction process is the same as step 【1】.

[0044] 【5】Repeat steps 【1】-【4】 to complete the construction of the high-toughness primary support structure of the soft rock tunnel.

[0045] In the process of tunnel construction according to the above steps, the primary support arch foot is constrained by the locking-anchor cable anchor pad. According to the principle of force interaction, the anchor pad will be subjected to the active thrust transmitted by the arch foot deformation. The constraint force of the anchor pad on the arch foot is essentially provided by the expansion slip resistance between the steel sleeve and the rigid hollow circular table in the locking-anchor cable deformation device.

[0046] When the force transmitted from the initial support arch foot to the steel sleeve is small, the interaction force between the steel sleeve and the rigid hollow truncated cone is less than the design resistance between them. No relative displacement occurs between the steel sleeve and the rigid hollow truncated cone, only the elastic deformation of the steel strand itself. When the force transmitted from the initial support arch foot to the steel sleeve is large, and the interaction force between the steel sleeve and the rigid hollow truncated cone is equal to the design resistance, the transition section and the unexpanded section of the steel sleeve undergo expansion deformation and relative displacement with the rigid hollow truncated cone due to the internal support force of the rigid hollow truncated cone, thus becoming part of the new expanded section. As the deformation of the initial support arch foot continues to increase, when the steel sleeve slides to the point where its internal retaining ring slides and contacts the rigid hollow truncated cone, the deformation device reaches its maximum sliding amount. The above process utilizes the relative slippage between the steel sleeve and the rigid hollow truncated cone to improve the adaptability and bearing toughness of the anchor cable to the deformation of the initial support arch foot. At the same time, the constant expansion slippage resistance generated during the relative slippage between the steel sleeve and the rigid hollow truncated cone provides a constant constraint force for the initial support arch foot, thereby improving the overall disaster resistance toughness of the initial support structure of soft rock tunnels with large deformation.

[0047] The above content is only for illustrating the technical concept of this utility model and should not be construed as limiting the scope of protection of this utility model. Any modifications made to the technical solution based on the technical concept proposed in this utility model shall fall within the scope of protection of the claims of this utility model.

Claims

1. A high-toughness locking foot anchor cable for a soft rock large deformation tunnel, characterized in that: The high-toughness lock-foot anchor cable comprises a steel strand, a deformation device and an anchor; the deformation device is composed of a steel sleeve and a hollow circular table, the steel sleeve comprises an expanded pipe section, a transition section and an unexpanded pipe section, the transition section is a conical cylinder structure and is connected between the expanded pipe section and the unexpanded pipe section, the small-diameter end of the hollow circular table is sleeved in the unexpanded pipe section of the steel sleeve, and the side surface of the hollow circular table is arranged close to the inner surface of the transition section; the steel sleeve is arranged in the sprayed concrete, and the large-diameter end of the hollow circular table is fixed on the steel strand through the anchor.

2. The high-toughness locking foot anchor cable for soft rock large deformation tunnel according to claim 1, characterized in that: The expanded pipe section is welded with an external clasp ring on the outer wall of the head.

3. The high-toughness locking foot anchor cable for soft rock large deformation tunnel according to claim 2, characterized in that: The external clasp ring is a hollow circular table structure, and the top and bottom of the circular table are connected through an arc surface.

4. The high-toughness locking foot anchor cable for soft rock large deformation tunnel according to claim 1, characterized in that: The unexpanded pipe section is welded with an internal clasp ring on the inner wall of the tail.

5. The high-toughness locking foot anchor cable for soft rock large deformation tunnel according to claim 1, characterized in that: A longitudinal connecting steel belt and an anchor pad are arranged between the external clasp ring and the outer surface of the sprayed concrete.

6. The high-toughness locking foot anchor cable for soft rock large deformation tunnel according to claim 1, characterized in that: The steel sleeve is made by locally expanding the steel pipe through an expanding machine.

7. A primary support for a soft rock, large deformation tunnel, characterised in that: The high-toughness lock-foot anchor cable comprises a steel frame, a steel mesh, a longitudinal connecting rib, a lock-foot anchor pipe, sprayed concrete and the high-toughness lock-foot anchor cable according to any one of claims 1 to 6; the steel mesh is laid behind the steel frame and is welded at the contact position with the steel frame; the lock-foot anchor pipe is arranged at the arch foot and the wall foot and is welded at the end with the steel frame.

8. The primary support for a large deformation tunnel in soft rock according to claim 7, characterized in that: A longitudinal connecting steel belt and an anchor pad are arranged between the external clasp ring of the steel sleeve and the outer surface of the sprayed concrete; the longitudinal connecting steel belt integrally connects adjacent high-toughness lock-foot anchor cables along the longitudinal direction of the tunnel.

9. The primary support for large deformation tunnel in soft rock according to claim 7, characterized in that: Longitudinal connecting ribs are arranged between adjacent steel frames.

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