A spiral anchor device and its construction method

Abstract

The present invention discloses a spiral anchor bolt anchoring device and a construction method thereof, which comprises a lower backing plate, an upper backing plate, a spiral spring, a locking nut and an anchor bolt. The lower backing plate and the upper backing plate are arranged in parallel. Two ends of the spiral spring are respectively connected with the inner sides of the lower backing plate and the upper backing plate. Through holes are formed in both the lower backing plate and the upper backing plate. The anchor bolt passes through the two through holes. The spiral spring is sleeved on the outer wall of the anchor bolt. The locking nut is installed on the anchor bolt and is arranged on the outer side of the upper backing plate. The advantages of the present invention are as follows: the equipment is simple, easy to operate and has a short construction period; the cost is low and the cost can be saved; the effective connection between the anchor head and the solid to be anchored can be effectively ensured; the on-site direct assembly and locking are convenient for construction.

Description

Technical Field

[0001] The present invention relates to the technical field of slope reinforcement, and particularly relates to a spiral anchor rod anchoring device and a construction method thereof. Background Art

[0002] With the advancement and development of China's infrastructure construction, a large number of slopes need to be supported in transportation engineering, hydropower and water conservancy projects, municipal engineering, geological disaster prevention and control, etc., and various protective measures emerge in an endless stream. More and more tunnels will pass through formations with high stress and weak rock mass. Such tunnels often face problems such as a large range of plastic zones in the surrounding rock, great difficulty in support, and great construction difficulty during the construction process. Anchor heads are actually widely used in the whole project and are applied in fields such as building reinforcement, slope stabilization, and structural installation. Anchor rods are the most basic components for roadway support in contemporary coal mines. They anchor the surrounding rock of the roadway together, enabling the surrounding rock to support itself. Now, anchor rods are not only used in mines but also in engineering technologies for main reinforcement of slopes, tunnels, and dams.

[0003] The existing external anchor heads of anchor rods generally use steel concrete cast in situ on the outside of the reinforced slope. It is necessary to form a mold on the steep and uneven rock surface and then use reinforced concrete for in-situ casting. The existing anchor head technologies of anchor rods either have cumbersome construction procedures, complex equipment, and high costs, or cannot effectively ensure the effective connection between the anchor head and the anchored solid, and have a long construction period, and the external anchor head is exposed. Therefore, aiming at the drawbacks of the current anchor head equipment and construction methods of anchor rods, the present invention needs to design a device and a construction method that are convenient for construction, have low costs, and can effectively ensure the effective connection between the anchor head and the anchored solid, aiming to solve the defects that the anchor head and the reinforced slope body cannot effectively contact and the process is complex and costly in the prior art. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems that the anchor head and the reinforced slope body cannot effectively contact and the process is complex and costly in the prior art.

[0005] The present invention is achieved through the following technical solutions:

[0006] A spiral anchor rod anchoring device includes a lower backing plate, an upper backing plate, a spiral spring, a locking nut, and an anchor rod. The lower backing plate and the upper backing plate are arranged in parallel. The two ends of the spiral spring are respectively connected to the inner sides of the lower backing plate and the upper backing plate. The lower backing plate and the upper backing plate are both provided with through holes. The anchor rod passes through the two through holes. The spiral spring is sleeved on the outer wall of the anchor rod. The locking nut is installed on the anchor rod, and the locking nut is arranged on the outside of the upper backing plate.

[0007] The prior art (application publication number CN109162287A) locks with nuts and anchor plates used for the anchor heads of anchor rods. When reinforcing soil slopes, soft rock slopes, and relatively soft rock slopes, plastic deformation is extremely likely to occur in the slope body under a certain pressure. Before grouting the anchor heads after locking, large plastic deformation is likely to occur at the contact between the anchor plate and the rock mass, resulting in the separation of the anchor plate from the reinforced slope surface during grouting of the anchor heads and ineffective anchoring. The prior art (authorized publication number CN208870620U) has a relatively small washer area, resulting in a large normal stress on the slope. It is not suitable for soil slopes, soft rock slopes, and extremely soft rock slopes that require a large anchoring force. In addition, the device installation is cumbersome, the project investment is large, the equipment is complex, and the anchor head equipment is exposed, which is not conducive to anti-corrosion protection and other safeguards.

[0008] In the present invention, an upper washer and a lower washer are connected by a helical spring. The lower washer and the upper washer are both provided with through holes, and the anchor rod passes through the two through holes. The locking nut is installed on the anchor rod and is located outside the upper washer. The mutual cooperation of each component makes the contact area between the anchoring device and the anchored slope larger than that of the constant-pressure anchor head device, achieving a prefabricated effect. After the anchoring mortar reaches the designed strength, simply level the slope surface, pass the spiral anchor rod anchoring device through the through holes of the upper and lower washers, and make the lower washer closely adhere to the slope surface. The equipment is simple, the cost is low, the investment is small, and it can be directly assembled and locked on-site, facilitating construction.

[0009] Further, it is advisable that the upper washer is located in the upper-middle part of the threaded section of the anchor rod, which is not prone to separation, has a small stress, can be used for relatively weak slope surfaces, and the anchoring is more reliable.

[0010] Further, both the lower washer and the upper washer are square.

[0011] The lower washer and the upper washer are made of square steel plates with a thickness of 20 mm and a side length of 25 cm.

[0012] Further, the inner diameters of both through holes are 33 - 40 mm.

[0013] The washers are perforated in the middle with a hole diameter of 35 mm.

[0014] Further, the thread specification of the locking nut adopts the M20 - M30 model.

[0015] The thread specification of the locking nut adopts the M20 - M30 model, and different models are selected according to the diameter of the anchor rod.

[0016] Further, the wire diameter of the helical spring is 8 - 12 mm, and the outer diameter at the bottom is 190 - 210 mm.

[0017] The helical spring is in the shape of a pagoda.

[0018] Further, the total number of turns of the helical spring is 5 - 7 turns.

[0019] The wire diameter is 10 mm, the outer diameter at the bottom of the spring is 200 mm, the inner diameter is 180 mm, the outer diameter on the side of the lower spring backing plate is 20 mm, the inner diameter is 18 mm, the outer diameter on the side of the upper spring backing plate is 100 mm, and the inner diameter is 80 mm.

[0020] Furthermore, the helical spring is connected to the lower backing plate and the upper backing plate by welding;

[0021] At the top and bottom of the helical spring, 50-mm arc-length segments are reserved for welding with the upper and lower backing plates, and the welding is carried out by fillet welding on both sides.

[0022] Furthermore, the rigidity modulus of the wire material of the helical spring is greater than or equal to 7300.

[0023] Furthermore, the helical spring is made of stainless steel wire.

[0024] A construction method for realizing a spiral anchor anchoring device includes the following steps:

[0025] S1: At the top and bottom of the helical spring, 50-mm arc-length segments are reserved for welding with the upper and lower backing plates, and the welding is carried out by fillet welding on both sides;

[0026] S2: Threading is carried out on the anchor head part of the anchor rod, the threading length is 10 cm, and the thread is matched with the inner diameter of the locking nut;

[0027] S3: The drill rig drills a hole on the slope that matches the anchor rod, and according to the design requirements, the anchor rod hole is drilled to the design depth according to the design hole diameter;

[0028] S4: The anchor rod and the grouting pipe are inserted into the drilled hole together, and the anchoring mortar is injected, and wait until the concrete strength reaches the design requirement value;

[0029] S5: The anchor rod passes through the through holes of the upper backing plate and the lower backing plate;

[0030] S6: The locking nut is tightened so that the lower backing plate fits closely against the slope surface;

[0031] S7: Sealing the anchor, after the anchor rod is locked, the anchoring device is sealed with pea gravel concrete.

[0032] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0033] 1. The spiral anchor anchoring device of the present invention has simple equipment, is easy to operate, and has a short construction period.

[0034] 2. The spiral anchor anchoring device of the present invention has low cost, saves costs, and has a small project investment.

[0035] 3. The spiral anchor rod anchoring device of the present invention has a larger contact area with the anchored slope than the constant pressure anchor head device, is not easily separated, has less stress, can be used for relatively soft slopes, and the anchoring is more reliable.

[0036] 4. The spiral anchor rod anchoring device of the present invention can be mass-produced in the factory and directly assembled and locked on-site, which is convenient for construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, form a part of this application, and do not limit the embodiments of the present invention. In the drawings:

[0038] Figure 1 It is a schematic diagram of the anchor rod anchoring device.

[0039] 1 - lower backing plate, 2 - upper backing plate, 3 - spiral spring, 4 - locking nut, 5 - anchor rod. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and the drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and do not limit the present invention.

[0041] Embodiment 1

[0042] As Figure 1 shown, the present invention is a spiral anchor rod anchoring device, including a lower backing plate 1, an upper backing plate 2, a spiral spring 3, a locking nut 4, and an anchor rod 5. The lower backing plate 1 and the upper backing plate 2 are arranged in parallel. The two ends of the spiral spring 3 are respectively connected to the inner sides of the lower backing plate 1 and the upper backing plate 2. The lower backing plate 1 and the upper backing plate 2 are both provided with through holes. The anchor rod 5 passes through the two through holes. The spiral spring 3 is sleeved on the outer wall of the anchor rod 5. The locking nut 4 is installed on the anchor rod 5. The locking nut 4 is arranged on the outer side of the upper backing plate 2, and the outer side is the side where the lower backing plate 1 and the upper backing plate 2 face each other.

[0043] Working process: 1. The anchor rod is anchored into the slope body, and a spiral anchor head is added; 2. The locking nut is tightened to apply pressure to the spring, and the spring is compressed, generating an outward elastic force on the upper and lower backing plates; 3. Due to the limiting effect of the locking nut, the upper backing plate cannot deform outward. Then, for the spring to elongate, it needs to deform towards the slope body direction, which will drive the lower backing plate to squeeze the slope surface, forming a reaction force system device, achieving the same effect as the existing hydraulic system, thus ensuring that the lower backing plate is always in close contact with the slope surface.

[0044] Embodiment 2

[0045] As Figure 1As shown in the figure, this embodiment is based on Embodiment 1. The lower backing plate 1 and the upper backing plate 2 are both square; the inner diameters of the two through holes are both 33 - 40 mm; the thread specification of the locking nut 4 adopts the M20 - M30 model; the wire diameter of the helical spring 3 is 8 - 12 mm, and the outer diameter at the bottom is 190 - 210 mm; the total number of turns of the helical spring 3 is 5 - 7 turns; the helical spring 3 is connected to the lower backing plate 1 and the upper backing plate 2 by welding; the rigidity modulus of the wire material of the helical spring 3 is greater than or equal to 7300; the helical spring 3 is made of stainless steel wire.

[0046] Embodiment 3

[0047] As Figure 1 shown in the figure, this embodiment is based on Embodiment 1 and Embodiment 2, and realizes a construction method of a spiral anchor anchoring device, including the following steps:

[0048] S1: Process the upper backing plate 2 and the lower backing plate 1. Cut a 20 - mm - thick steel plate into squares of 15×15 cm and 25×25 cm, and then mill a through hole with a diameter of 35 mm at the center of the steel plate. Reserve arc - length segments of 50 mm at the top and bottom of the helical spring 3, and weld them to the upper and lower backing plates 1.

[0049] S2: Thread the anchor head part of the anchor rod 5. The threading length is 10 cm, and the thread is in line with the inner diameter of the locking nut 4.

[0050] S3: The drill rig drills a hole on the slope that matches the anchor rod 5. According to the design requirements, drill the hole to the design depth according to the design hole diameter.

[0051] S4: Insert the anchor rod 5 and inject the anchoring mortar. Insert the anchor rod 5 and the grouting pipe together into the drilled hole, inject the anchoring mortar, and wait until the concrete strength reaches the design requirement value (concrete equal - strength).

[0052] S5: After the anchoring mortar reaches the design strength, simply level the slope surface. Pass the anchor rod 5 through the through holes of the upper backing plate 2 and the lower backing plate 1. The lower backing plate 1 is closely attached to the slope surface, and the upper backing plate 2 is preferably located in the upper - middle part of the threaded part of the anchor rod 5.

[0053] S6: Lock the anchor rod 5. For a general anchor rod 5, tighten the locking nut 4 so that the lower backing plate 1 is closely attached to the slope surface; for a prestressed anchor rod 5, use a torque wrench to lock the tensile value of the anchor rod 5 at the design value.

[0054] The torque calculation formula for locking the prestressed anchor rod with the torque wrench is as follows:

[0055]

[0056] Among them, M is the torque applied by the wrench (kN·m), N is the designed value of the axial force of the prestressed anchor rod (kN), f is the dynamic friction coefficient between the locking nut and the upper backing plate, which is obtained through tests according to the materials of the backing plate and the locking nut used. If there is no test value, it can be approximately taken as 0.15. ρ is the equivalent friction angle of the screw pair, tgρ is the equivalent friction coefficient of the screw pair, tgρ = f’ / cosβ, β is the half thread angle, for a triangular thread, β = 30°, f’ is the friction coefficient between the screw pairs, λ is the lead angle of the thread, tgλ = t / πd2, t is the pitch, d2 is the pitch diameter of the thread, R is the outer radius of the nut bearing surface (m), and r is the radius of the anchor rod (m).

[0057] S7: Sealing the anchor. Since the anchoring device applies pressure to the slope surface by using the spiral spring 3, in order to avoid the reduction of pressure caused by the plastic deformation of the spring in the later stage, after the anchor rod 5 is locked, crushed stone concrete is used to seal the anchoring device. The concrete is poured into the spiral anchoring device and tightly wraps the spring.

[0058] While ensuring the same anchoring force, the present invention reduces the normal stress generated on the slope surface, reduces the deformation of the slope surface at the anchoring point, and enhances the overall anchoring effect of the slope.

[0059] The above-described specific embodiments have further elaborated on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A spiral anchor bolt anchoring device, characterized in that It includes a lower backing plate (1), an upper backing plate (2), a helical spring (3), a locking nut (4) and an anchor rod (5). The lower backing plate (1) and the upper backing plate (2) are arranged in parallel. The two ends of the helical spring (3) are respectively connected to the inner sides of the lower backing plate (1) and the upper backing plate (2). Both the lower backing plate (1) and the upper backing plate (2) are provided with through holes. The anchor rod (5) passes through the two through holes. The helical spring (3) is sleeved on the outer wall of the anchor rod (5). The locking nut (4) is installed on the anchor rod (5). The locking nut (4) is arranged on the outer side of the upper backing plate (2). Both the lower backing plate (1) and the upper backing plate (2) are square. The area of the lower backing plate (1) is larger than the area of the upper backing plate (2). The wire diameter of the helical spring (3) is 8 - 12 mm, and the outer diameter at the bottom is 190 - 210 mm. The helical spring (3) is connected to the lower backing plate (1) and the upper backing plate (2) by welding. The rigidity modulus of the wire material of the helical spring (3) is greater than or equal to 7300, and the bottom of the helical spring (3) is fixedly connected to the lower backing plate (1). The lower backing plate (1), the upper backing plate (2) and the helical spring (3) are connected into an anchor head by grouting with gravel concrete.

2. The spiral anchor device according to claim 1, characterized in that, The inner diameters of both through holes are 33 - 40 mm.

3. The spiral anchor device according to claim 1, characterized in that, The thread specification of the locking nut (4) adopts the M20 - M30 model.

4. A spiral anchor device according to claim 1, characterized in that, The total number of turns of the helical spring (3) is 5 - 7 turns.

5. The spiral anchor device according to claim 1, characterized in that, The helical spring (3) is made of stainless steel wire.

6. A construction method of a spiral anchor rod anchoring device according to any one of claims 1-5, characterized in that, It includes the following steps: S1: Reserve an arc length section of 50 mm at the top and bottom of the helical spring (3) and weld it to the lower backing plate (1) and the upper backing plate (2). S2: Thread the anchor head part of the anchor rod (5) so that the thread matches the inner diameter of the locking nut (4). S3: The drill rig drills a hole on the slope that matches the anchor rod (5). S4: Insert the anchor rod (5) into the hole and inject the anchoring mortar. S5: Pass the anchor rod (5) through the through holes of the upper backing plate (2) and the lower backing plate (1). S6: Tighten the locking nut (4) so that the lower backing plate (1) fits tightly against the slope. S7: Seal the anchor, and pour the concrete into the spiral anchoring device.

Images