A double-tube constant-resistance anchor rod for deep foundation pit blasting excavation

Abstract

The present invention relates to a double-tube constant-resistance anchor rod for deep foundation pit blasting excavation, belonging to the field of anchoring and support. It includes a constant-resistance section, a free section, an anchoring section, and an external tensioning device. The constant-resistance section is composed of an expansion tube, a extrusion tube, a cone, a connecting member, and a connecting tube. The end of the connecting tube is connected to the rod body of the free section through a thread. The end of the rod body of the free section is an enlarged-diameter anchor head, and the outer diameter of the anchor head is a slurry discharge groove. The anchor rod body is a hollow structure, which can be pressure grouted and can provide an effective anchoring force. When the anchor rod is impacted by blasting vibration, through the extrusion of the cone on the tube wall of the casing, a large frictional resistance is generated, which can effectively offset the blasting impact energy. At the same time, rubber sheets are added at the anchor head and the anchor tail to further improve the earthquake resistance of the anchor rod. The structure of the present invention is simple, and all connections are threaded connections, which is convenient for construction. It can provide continuous and constant resistance, and can effectively prevent the brittle fracture phenomenon of the anchor rod when dealing with the impact vibration generated during blasting construction, and the structure is stable and reliable.

Description

Technical Field

[0001] The invention belongs to the field of anchoring support, and particularly relates to a double - sleeve constant - resistance anchor rod for deep foundation pit blasting excavation. Background Technique

[0002] The anchor rod support technology is an engineering technical means of burying the anchor rod into the rock and soil mass to a certain depth to improve the strength of the rock and soil mass and maintain its stability. The reinforcement mechanism of the anchor rod support can be divided into suspension, combined beam, reinforcement and enhancement, internal pressure, rock shell, support and pin functions. A quarry in North Wales, UK in 1872 is the earliest known example of the application of the anchor rod support technology. The anchor rod support has the advantages of low cost, fast action and good support effect, and has been widely used in the fields of mining, transportation, water conservancy, municipal engineering and other underground engineering.

[0003] For the deep foundation pit of the subway station, generally, retaining piles combined with reinforced concrete supports, steel supports and prestressed anchor rods are used as the support structure. For the deep subway foundation pit mainly composed of rock strata, the blasting excavation construction plan is inevitably adopted. Under the action of deep foundation pit blasting excavation, the support structure has large speed and deformation. The deformation capacity of ordinary anchor rods is small. When subjected to blasting impact loads, the failure behaviors of anchor rods usually have the following forms: one is the brittle fracture phenomenon of the anchor rod body being pulled or cut off due to the small deformation capacity of the rod body; the second is the damage of the outer anchor tray and nut; the third is the pull - off of the end rod body and the anchoring agent, or the pull - off of the anchoring agent and the rock mass, resulting in the failure of the anchoring section. When the anchor rod fails, it will further cause the damage of other support structures, posing a great safety hazard. Therefore, the problem that ordinary anchor rods have large deformation and fail under blasting vibration must be paid enough attention. Therefore, developing a constant - resistance anchor rod to ensure that the anchor rod does not undergo brittle fracture under large deformation conditions during deep foundation pit blasting excavation and ensuring the safety and effectiveness of the anchor rod has become an urgent problem to be solved. Summary of the Invention

[0004] In order to solve the above problems, the invention provides a double - sleeve constant - resistance anchor rod for deep foundation pit blasting excavation, which uses the extrusion between the cone and the sleeve wall to generate a huge frictional resistance, which can effectively offset the blasting impact energy. At the same time, rubber sheets are added at the anchor head and the anchor tail to further improve the seismic resistance of the anchor rod, solving the problem that the rod body of the traditional anchor rod is prone to brittle fracture under blasting excavation conditions. At the same time, the invention sets an enlarged - diameter anchor head at the anchoring section that can be connected to the end of the rod body, which can realize rod body grouting and good anchoring effect, solving the problems of complex construction caused by the need to set up another grouting pipe for grouting in the traditional technology, and the problem that the anchor rod and the anchoring agent at the anchoring section are prone to pull - off, resulting in anchor rod failure.

[0005] The technical solution adopted by the invention is as follows:

[0006] A double-tube constant-resistance anchor rod for deep foundation pit blasting excavation, characterized in that it includes a constant-resistance section, a free section, an anchorage section and an external tensioning device. The constant-resistance section includes a data transmitter, a data line, a sensor, an expansion tube, a squeezing tube, a connecting member, a cone, a connecting pipe and a waterproof rubber strip; the expansion tube includes an expansion tube connecting section, an expansion section and an outer tail end clamp, and the squeezing tube includes a squeezing tube connecting section, a squeezing section and an inner tail end clamp. The expansion tube connecting section is connected to the connecting member through the inner wall thread at the end, and the squeezing tube connecting section is connected to the connecting member through the outer wall thread at the end; the cone is placed between the expansion tube connecting section and the squeezing tube connecting section, and the connecting pipe is placed between the expansion section and the squeezing section, and the axes of the expansion tube, the squeezing tube, the cone and the connecting pipe coincide; one end of the cone is a connecting thread for connecting with the connecting pipe, and the other end is a hollow cylinder, and the middle is a hollow frustum; the hollow part inside the hollow frustum is funnel-shaped, and the outer wall diameter gradually increases from the connecting thread end to the hollow cylinder end, and the inner wall diameter gradually decreases; the outer wall diameter of the hollow cylinder is equal to the inner wall diameter of the expansion tube connecting section and is larger than the inner wall diameter of the expansion section, and the inner wall diameter of the hollow cylinder is equal to the outer wall diameter of the squeezing tube connecting section and is smaller than the inner wall diameter of the squeezing section; when the deep foundation pit is blasted and excavated, the shock wave is transmitted to the anchor rod through the rock and soil body, and the rod body of the anchor rod is subjected to axial tension. The connecting rod transmits the force to the cone, causing the cone to have a forward movement tendency. Since the inner wall diameter of the expansion section in front of the cone is smaller than the diameter of the hollow cylinder at the end of the cone, when the cone passes through the expansion section, the inner wall of the expansion tube is squeezed, and the tube body undergoes radial expansion deformation. The cone moves forward, and the anchor rod undergoes large deformation, while consuming the energy of the blasting shock wave and the energy released by the deformation of the rock and soil body.Similarly, when the cone passes through the extrusion section, the outer wall of the extrusion pipe is squeezed by the cone, the pipe body is compressed, the diameter of the pipe body decreases, the cone moves forward, the anchor rod undergoes large deformation, and at the same time, the energy of the blasting shock wave and the energy released by the deformation of the rock and soil mass are consumed; the waterproof rubber strips are distributed and pasted at the ends of the inner end clamp and the outer end clamp to prevent external water and grouting slurry from entering the inside of the expansion pipe and the extrusion pipe to cause corrosion; the sensor is placed in the space formed by the expansion pipe, the extrusion pipe, the connecting member and the cone and fixed on the cone, and is connected to the data transmitter through a data line. The data transmitter is fixed at the free face end. The moving distance of the cone is monitored in real time through the sensor, and the data is transmitted to the control center through the data transmitter, so that the mechanical changes inside the deep foundation pit can be completely monitored and early warnings can be issued before disasters occur; the external tensioning device includes fastening bolts, wedge-shaped iron, rubber plates, and waist beams. The rubber plates are placed on the waist beams, the wedge-shaped iron is placed on the rubber plates, and one end of the connecting member passes through the wedge-shaped iron, the rubber plates, and the waist beam and is fixed by the fastening bolts. The rubber plates can buffer the shock wave received at the external tensioning device to prevent the shear failure of the fastening bolts; the anchoring section consists of an enlarged-diameter anchor head and an end cap. The enlarged-diameter anchor head includes a cylindrical section, a conical section, grooves, and shock-absorbing rubber sheets. One end of the cylindrical section is connected to the conical section, and one end is connected to the shock-absorbing rubber sheets. The shock-absorbing rubber sheets can buffer the shock wave received by the anchoring section; when grouting, to prevent the enlarged-diameter anchor head from completely blocking the anchor hole, four grooves are evenly arranged on the enlarged-diameter anchor head. After the slurry flows out from the end of the free-section rod body, it flows out through the four grooves; the enlarged-diameter anchor head passes through the end of the free-section rod body and is fixed to the end of the free-section rod body, which can not only improve the anchoring force but also allow the grouting slurry to pass through; the end cap is placed on the end of the free-section rod body to prevent the end of the free-section rod from pressing against the anchor hole and causing grouting failure.

[0007] Furthermore, the expansion pipe and the extrusion pipe have the same length, and tiny threads or protrusions can be provided on the inner wall of the expansion pipe and the outer wall of the extrusion pipe to increase the friction force.

[0008] Furthermore, the expansion pipe is a tubular structure and is integrally formed by a mold. The wall thickness of the connection section and the expansion section of the expansion pipe is the same, and the diameter of the wall of the connection section of the expansion pipe is 1 mm - 6 mm larger than that of the wall of the expansion section, which can be adjusted according to the support environment; the wall thickness of the pipe wall gradually thickens from the outer end clamp inward until the minimum inner wall radius is the same as the outer wall radius of the connecting pipe, and this wall thickness is axially extended by 20 mm - 40 mm to prevent the cone from being pulled out.

[0009] Further, the extrusion tube is of a tubular structure and is integrally formed by a mold. The wall thickness of the connection section and the extrusion section of the extrusion tube is the same, and the diameter of the wall of the connection section of the extrusion tube is 0.5 mm - 3 mm smaller than that of the wall of the extrusion section, which can be adjusted according to the support environment. The wall thickness of the extrusion tube gradually thickens from the inner end to the outside until the maximum outer wall radius is the same as the inner wall radius of the connection tube, and this wall thickness is axially extended by 20 mm - 40 mm to prevent the cone from being pulled out.

[0010] Further, one end of the connecting member is a hollow threaded rod, which is connected to the fastening bolt, and the other end is a hollow cylinder. The inner and outer circumferential walls of the hollow cylinder are threaded and are threadedly adapted and connected to the ends of the expansion tube and the extrusion tube.

[0011] Further, the end cap is a tube body with one end closed, and there are several openings on the side wall of the tube body. After the slurry flows out from the end of the free section rod body, it flows out through the openings on the side wall of the end cap tube body.

[0012] Further, the cone and the connecting tube are connected by end threads, and can also be welded or integrally formed in the factory.

[0013] Further, the inner wall of the enlarged-diameter anchor head is provided with threads and is threadedly connected to the free section rod body or welded to the free section rod body.

[0014] Further, the thickness of the rubber plate and the shock-absorbing rubber sheet is 10 mm - 30 mm to ensure the shock-absorbing effect.

[0015] The beneficial effects of the present invention:

[0016] The effects and advantages of the present invention are that the structure is simple, the joints are all threaded connections, the construction is convenient, it can provide continuous and constant resistance, has a large elongation, can effectively cope with the impact force generated during the blasting excavation process, the anchor rod is integrally a hollow structure, the end of the rod body is an enlarged-diameter anchor head, pressure grouting can be carried out, reducing the construction steps, speeding up the construction speed, the anchoring section can provide effective anchoring force, the support structure can be monitored in real time, has an early warning effect, the structure is stable and reliable, and meets the requirements of on-site rapid construction. Description of the drawings

[0017] Figure 1 is a schematic structural diagram of a double-tube constant-resistance anchor rod for deep foundation pit blasting excavation according to the present invention;

[0018] Figure 2 is a schematic structural diagram of the anchor rod support after deformation;

[0019] Figure 3 is Figure 1 the sectional view taken along line 1-1 in

[0020] Figure 4Schematic diagram of the connection between the extrusion pipe, the cone and the connecting pipe;

[0021] Figure 5 Sectional view of the yielding section structure;

[0022] Figure 6 Schematic diagram of the external shape of the yielding section structure;

[0023] Figure 7 Schematic diagram of the external shape of the cone;

[0024] Figure 8 Exploded view of the cone;

[0025] Figure 9 Schematic diagram of the anchorage section structure;

[0026] Figure 10 Exploded view of the anchorage section structure.

[0027] In the figure, 1 is the grouting port; 2 is the fastening bolt; 3 is the wedge; 4 is the rubber plate; 5 is the waist beam; 6 is the data transmitter; 7 is the data line; 8 is the sensor; 9 is the expansion pipe; 9-1 is the expansion pipe connection section; 9-2 is the expansion section; 9-3 is the outer end clamp; 10 is the extrusion pipe; 10-1 is the extrusion pipe connection section; 10-2 is the extrusion section; 10-3 is the inner end clamp; 11 is the connecting member; 12 is the cone; 12-1 is the hollow cylinder; 12-2 is the hollow frustum; 12-3 is the connecting thread; 13 is the connecting pipe; 14 is the waterproof rubber strip; 15 is the free section rod body; 16 is the enlarged diameter anchor head; 16-1 is the column section; 16-2 is the cone section; 16-3 is the groove; 16-4 is the shock-absorbing rubber sheet; 17 is the end cap. Detailed implementation manners

[0028] The present invention will be described in detail below with reference to the accompanying drawings and embodiments:

[0029] Embodiment:

[0030] As Figures 1 - 3As shown in the figure, a double - sleeve constant - resistance bolt for deep foundation pit blasting excavation is characterized in that it includes a constant - resistance section, a free section, an anchorage section and an external tensioning device. The constant - resistance section includes a data transmitter (6), a data line (7), a sensor (8), an expansion tube (9), a squeezing tube (10), a connecting member (11), a cone (12), a connecting pipe (13), and a waterproof rubber strip (14). One end of the connecting member (11) is a hollow threaded rod, which is connected to the fastening bolt (2), and the other end is a hollow cylinder. The inner and outer circumferential walls of the hollow cylinder are threaded. The expansion tube (9) is connected to the connecting member (11) through the inner wall thread at the end, and the squeezing tube is connected to the connecting member (11) through the outer wall thread at the end. The cone (12) is connected to the connecting pipe (13) and is placed between the expansion tube (9) and the squeezing tube (10), and the axes of the expansion tube (9), the squeezing tube (10), the cone (12) and the connecting pipe (13) coincide. The waterproof rubber strip (14) is distributed and pasted at the ends of the inner end clamp (10 - 3) and the outer end clamp (9 - 3). The sensor (8) is placed in the space formed by the expansion tube (9), the squeezing tube (10), the connecting member (11) and the cone (12) and is fixed on the cone (12), and is connected to the data transmitter (6) through the data line (7). The data transmitter (6) is fixed at the free - face end. The external tensioning device includes a fastening bolt (2), a wedge iron (3), a rubber plate (4), and a waist beam (5). The rubber plate (4) is placed on the waist beam (5), the wedge iron (3) is placed on the rubber plate (4), and one end of the connecting member (11) passes through the wedge iron (3), the rubber plate (4), and the waist beam (5) and is fixed by the fastening bolt (2). The anchorage section is composed of an enlarged - diameter anchor head (16) and an end cap (17). The enlarged - diameter anchor head (16) passes through the end of the free - section rod body (15) and is fixed at the end of the free - section rod body (15). The end cap (17) is placed on the end of the free - section rod body (15). When the bolt is affected by external factors, the constant - resistance section begins to deform, the cone (12) produces relative slip, and finally the overall length of the bolt increases.

[0031] As Figures 4 - 8As shown, the cone (12) consists of a hollow cylinder (12-1), a hollow frustum (12-2) and a connecting thread (12-3). One end of the cone (12) is the connecting thread (12-3) for connecting to the connecting pipe (13), the other end is the hollow cylinder (12-1), and the middle part is the hollow frustum (12-2). The inner hollow part of the hollow frustum (12-2) is funnel-shaped. From the connecting thread (12-3) to the outer wall of the hollow cylinder (12-1), the diameter gradually decreases, and the inner wall diameter gradually increases. The outer wall diameter of the hollow cylinder (12-1) is equal to the inner wall diameter of the expansion pipe connection section (9-1) and greater than the inner wall diameter of the expansion section (9-2). The inner wall diameter of the hollow cylinder (12-1) is equal to the outer wall diameter of the extrusion pipe connection section (10-1) and less than the outer wall diameter of the extrusion section (10-2). The expansion pipe (9) includes an expansion pipe connection section (9-1), an expansion section (9-2), and an outer end clamp (9-3). The extrusion pipe (10) includes an extrusion pipe connection section (10-1), an extrusion section (10-2), and an inner end clamp (10-3). The cone (12) is placed between the expansion pipe connection section (9-1) and the extrusion pipe connection section (10-1), and the connecting pipe (13) is placed between the expansion section (9-2) and the extrusion section (10-2). Moreover, the axes of the expansion pipe (9), the extrusion pipe (10), the cone (12) and the connecting pipe (13) coincide. When the deep foundation pit is excavated by blasting, the shock wave is transmitted to the anchor through the rock and soil mass. The anchor rod body is subjected to axial tension. The connecting pipe (13) transmits the force to the cone (12), causing the cone (12) to have a forward movement tendency. Since the inner wall diameter of the expansion section (9-2) in front of the cone (12) is smaller than the diameter of the hollow cylinder (12-1) at the end of the cone (12), when the cone (12) passes through the expansion section (9-2), the inner wall of the expansion pipe (9) is squeezed, and the pipe body undergoes radial expansion deformation. The cone (12) moves forward, and the anchor rod undergoes large deformation. At the same time, the energy of the blasting shock wave and the energy released by the deformation of the rock and soil mass are consumed. Similarly, when the cone (12) passes through the extrusion section (10-2), the outer wall of the extrusion pipe (10) is squeezed by the cone (12), the pipe body is compressed, and the pipe body diameter decreases. The cone (12) moves forward, and the anchor rod undergoes large deformation. At the same time, the energy of the blasting shock wave and the energy released by the deformation of the rock and soil mass are consumed.

[0032] As Figures 9 - 10The enlarged-diameter anchor head (16) shown includes a cylindrical section (16-1), a conical section (16-2), a groove (16-3), a shock-absorbing rubber sheet (16-4). One end of the cylindrical section (16-1) is connected to the conical section (16-2), and one end is connected to the shock-absorbing rubber sheet (16-4). The shock-absorbing rubber sheet (16-4) can buffer the shock wave received by the anchoring section. Four grooves (16-3) are evenly distributed on the cylindrical section (16-1) and the conical section (16-2) to allow the grouting slurry to pass through. The end cap (17) is a pipe body with one end closed, and there are several openings on the side wall of the pipe body. After the slurry flows out from the end of the free-section rod, it flows out through the openings on the side wall of the pipe body of the end cap (17).

[0033] The present invention will be described below in combination with the specific construction process:

[0034] At the pre-determined point, use a drill to drill a hole. The diameter of the drill hole is slightly larger than the diameter of the enlarged-diameter anchor head (16). After reaching the predetermined depth, withdraw the drill, replace the drill bit for re-drilling. The diameter of the re-drilling is slightly larger than the diameter of the expansion tube (9), and the re-drilling depth is the depth where the waterproof rubber strip (14) is located. Remove the drill, use a blower to clean the hole, and detect whether the depth and width of the anchor hole meet the requirements. Install the sensor (8) at the end of the hollow cylinder (12-1) of the cone (12) and connect it to the data line (7). Install and connect the data transmitter (6). Pass the extrusion tube (10) through the cone (12) and connect it to the connecting member (11) by thread. Pass the connecting tube (13) through the end of the inner tail end clamp (10-3) of the extrusion tube (10) and connect it to the cone (12). Finally, pass the expansion tube (9) through the connecting tube (13) and connect it to the connecting member (11). Distribute and paste the waterproof rubber strip (14) at the ends of the inner tail end clamp (10-3) and the outer tail end clamp (9-3). The constant-resistance section assembly is completed;

[0035] Connect the connecting tube (13) to the free-section rod body (15). Connect the end of the free-section rod body (15) to the enlarged-diameter anchor head (16) and the end cap (17). Paste the shock-absorbing rubber sheet (16-4) on the surface of the conical section (16-2) of the enlarged-diameter anchor head (16). The main part of the anchor rod is assembled;

[0036] Slowly send the anchoring section of the anchor rod into the anchor hole. After reaching the bottom of the anchor hole, detect whether the position of the anchor rod meets the requirements. Inject grout along the grouting port (1) through the grouting machine. After flowing out from the end of the free-section rod, it flows out through the openings on the side wall of the pipe body of the end cap (17), and flows out through the groove (16-3) until the anchor hole is filled;

[0037] After 3 to 7 days of grouting, check whether the predetermined anchoring strength is achieved. After reaching the predetermined strength, pass one end of the connecting member (11) through the inclined iron (3), rubber plate (4), and waist beam (5), and perform prestress tensioning with tensioning equipment. The tensioned prestress is 50% - 80% of the constant resistance of the anchor bolt, and it is fixed by the pre-tightening bolt (2).

Claims

1. A double - sleeve constant - resistance anchor rod for deep foundation pit blasting excavation, characterized in that: It includes a constant resistance section, a free section, an anchorage section and an external tensioning device. The constant resistance section includes a data transmitter (6), a data line (7), a sensor (8), an expansion tube (9), a squeezing tube (10), a connecting member (11), a cone (12), a connecting tube (13), and a waterproof rubber strip (14); the expansion tube (9) includes an expansion tube connecting section (9-1), an expansion section (9-2), an outer end clamp (9-3), and the squeezing tube (10) includes a squeezing tube connecting section (10-1), a squeezing section (10-2), and an inner end clamp (10-3). The expansion tube connecting section (9-1) is connected to the connecting member (11) through the inner wall thread at the end, and the squeezing tube connecting section (10-1) is connected to the connecting member (11) through the outer wall thread at the end; the cone (12) is placed between the expansion tube connecting section (9-1) and the squeezing tube connecting section (10-1), and the connecting tube (13) is placed between the expansion section (9-2) and the squeezing section (10-2), and the axes of the expansion tube (9), the squeezing tube (10), the cone (12) and the connecting tube (13) coincide; one end of the cone (12) is a connecting thread (12-3) for connecting with the connecting tube (13), the other end is a hollow cylinder (12-1), and the middle part is a hollow frustum (12-2); the inner hollow part of the hollow frustum (12-2) is funnel-shaped, and the outer wall diameter gradually increases from the connecting thread (12-3) to the hollow cylinder (12-1), and the inner wall diameter gradually decreases; the outer wall diameter of the hollow cylinder (12-1) is equal to the inner wall diameter of the expansion tube connecting section (9-1), larger than the inner wall diameter of the expansion section (9-2), the inner wall diameter of the hollow cylinder (12-1) is equal to the outer wall diameter of the squeezing tube connecting section (10-1), and smaller than the outer wall diameter of the squeezing section (10-2); the waterproof rubber strip (14) is distributed and pasted at the ends of the inner end clamp (10-3) and the outer end clamp (9-3); the sensor (8) is placed in the space formed by the expansion tube (9), the squeezing tube (10), the connecting member (11) and the cone (12) and fixed on the cone (12), and is connected to the data transmitter (6) through the data line (7), and the data transmitter (6) is fixed at the end of the free face; the external tensioning device includes a fastening bolt (2), a wedge iron (3), a rubber plate (4), and a collar beam (5). The rubber plate (4) is placed on the collar beam (5), the wedge iron (3) is placed on the rubber plate (4), and one end of the connecting member (11) passes through the wedge iron (3), the rubber plate (4), and the collar beam (5) and is fixed by the fastening bolt (2); the anchorage section is composed of an enlarged diameter anchor head (16) and an end cap (17). The enlarged diameter anchor head (16) includes a column section (16-1), a cone section (16-2), a groove (16-3), and a shock-absorbing rubber sheet (16-4); one end of the column section (16-1) is connected to the cone section (16-2), and one end is connected to the shock-absorbing rubber sheet (16-4). Four grooves (16-3) are evenly distributed on the column section (16-1) and the cone section (16-2); the enlarged diameter anchor head (16) passes through the end of the free section rod body (15) and is fixed at the end of the free section rod body (15).The end cap (17) is placed on the end of the free-section rod body (15).; 2. The double - sleeve constant - resistance anchor rod for deep foundation pit blasting excavation according to claim 1, characterized in that: The expansion tube (9) and the extrusion tube (10) have the same length. Minute threads or protrusions are provided on the inner wall of the expansion tube (9) and the outer wall of the extrusion tube (10) to increase friction.

3. The double-casing constant-resistance anchor rod for deep foundation pit blasting excavation according to claim 1, characterized in that: The expansion tube (9) is of a tubular structure and is integrally formed by a mold. The wall thicknesses of the tube wall of the connection section (9-1) and the expansion section (9-2) of the expansion tube are the same, and the diameter of the tube wall of the connection section (9-1) of the expansion tube is 1 mm - 6 mm larger than the diameter of the tube wall of the expansion section (9-2); the wall thickness of the tube wall gradually thickens inward from the outer end catch (9-3) until the minimum inner wall radius is the same as the outer wall radius of the connecting tube (13), and this wall thickness is axially extended by 20 mm - 40 mm.

4. The double-casing constant-resistance anchor rod for deep foundation pit blasting excavation according to claim 1, characterized in that: The extrusion tube (10) is of a tubular structure and is integrally formed by a mold. The wall thicknesses of the tube wall of the connection section (10-1) and the extrusion section (10-2) of the extrusion tube are the same, and the diameter of the tube wall of the connection section (10-1) of the extrusion tube is 0.5 mm - 3 mm smaller than the diameter of the tube wall of the extrusion section (10-2); the wall thickness of the tube wall of the extrusion tube (10) gradually thickens outward from the inner end catch (10-3) until the maximum outer wall radius is the same as the inner wall radius of the connecting tube (13), and this wall thickness is axially extended by 20 mm - 40 mm.

5. The double - sleeve constant - resistance bolt for deep foundation pit blasting excavation according to claim 1, wherein: One end of the connecting member (11) is a hollow threaded rod, which is connected to the fastening bolt (2), and the other end is a hollow cylinder. Threads are provided on the inner and outer circumferential walls of the hollow cylinder, which are thread-fitted and connected to the ends of the expansion tube (9) and the extrusion tube (10).

6. The double - sleeve constant - resistance anchor rod for deep foundation pit blasting excavation according to claim 1, characterized in that: The end cap (17) is a tube body with one end closed, and there are several openings on the side wall of the tube body. Pressurized grouting is carried out from the grouting port (1) and flows out from the end cap (17).

7. The double - sleeve constant - resistance anchor rod for deep foundation pit blasting excavation according to claim 1, characterized in that: The cone (12) and the connecting tube (13) are connected by end threads, can also be welded, or integrally formed in the factory.

8. The double - sleeve constant - resistance bolt for deep foundation pit blasting excavation according to claim 1, wherein: Threads are provided on the inner wall of the enlarged diameter anchor head (16), and it is thread-connected to the free section rod body (15) or welded to the free section rod body (15).

9. The double-casing constant-resistance anchor rod for deep foundation pit blasting excavation according to claim 1, wherein: The thickness of the rubber plate (4) and the shock-absorbing rubber sheet (16-4) is 10 mm - 30 mm.

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