Grouting device, downward-facing anchor cable equipped with automatic grouting device, and grouting method

Abstract

The present invention discloses a grouting-stopping device, a downward-bending anchor cable provided with an automatic grouting-stopping device, and a grouting method, wherein the automatic grouting-stopping device includes a casing, an annular baffle at the inlet end, an annular baffle at the outlet end, a valve plate, and a spring. The downward-bending anchor cable provided with an automatic grouting-stopping device includes a steel strand, an anchor head, an anchor pier, and a grouting pipe, and also includes an automatic grouting-stopping device; the grouting method includes the following steps: S1. Mixing ingredients to prepare cement material; S2. Mixing water and cement material in proportion to prepare cement slurry; S3. Grouting once; S4. Grouting twice. The downward-bending anchor cable provided with an automatic grouting-stopping device and the grouting method provided by the present invention can effectively control the length of the anchoring section during the grouting process, accurately distinguish the anchoring section from the free section, and when the length of the grouting liquid reaches the design value of the anchoring section length, the grouting pipe can be automatically and immediately blocked to avoid excessive injection of slurry in the anchoring section, thereby ensuring construction requirements while reducing raw material costs.

Description

Technical field:

[0001] The present invention relates to the technical field of rock and soil reinforcement engineering, and in particular to a grouting stop device, a downward-facing anchor cable provided with an automatic grouting stop device, and a grouting method. Background technology:

[0002] Currently, prestressed anchor cables are widely used in geotechnical engineering due to their convenience and cost-effectiveness in applications such as building foundation pit support and open-pit mine slope reinforcement. A prestressed anchor cable consists of an anchor head and a cable body. The cable body consists of an anchor section fixed to the bottom of the anchor hole and a free section that can stretch under the action of prestress.

[0003] During the installation of the anchor cable, an anchor hole is first opened on the rock and soil mass that needs to be reinforced. After the anchor cable is installed in the anchor hole, cement slurry is injected into the anchor hole to partially or completely fill the drilled space around the anchoring section of the cable body, so that the section of the cable body that extends into the anchor hole (i.e., the anchoring section) is bonded to the rock and soil mass. After the cement slurry solidifies and reaches a predetermined strength, a prestressed tension is applied to the end of the cable body where the anchor head is installed. The anchor head is locked by the anchor pier, and the tensioned cable body is fixed to the rock wall at the anchor hole, thereby achieving anchoring of the unstable rock and soil mass. When grouting the anchor hole, the cement slurry needs to have a certain pressure to plug the cracks around the hole wall of the anchor hole and improve the density of the grouting body in the drill hole. Research data shows that using an excessively long cable anchoring section does not increase the anchoring force; therefore, in the actual construction process, for working conditions where a free cable section is designed, it is necessary to accurately and effectively control the length of the anchoring section so that the free section length meets the design requirements, in order to save materials and manpower, reduce project costs, and improve construction efficiency.

[0004] At present, the length of the anchoring section is mainly controlled by installing a grouting stop structure on the anchor cable. According to the different installation positions of the grouting stop structure on the anchor cable, traditional anchor cables can be divided into two categories: hole-stop grouting type and in-hole grouting type.

[0005] 1. Hole-stop anchors feature a stopper structure installed at the hole. During grouting, the stopper completely fills the hole with cement slurry. This seals the hole to a certain extent, allowing the slurry to penetrate cracks around the hole wall under pressure and increase its density while preventing the injected slurry from leaking out of the hole. However, this type of anchor has limited application and is suitable for full-hole grouting. It is not suitable for anchors designed with a free section.

[0006] 2. In-hole grouting anchors are anchors with grouting structures placed on them in the anchor holes. The grouting structures mainly include silicone plate anchor grouting plugs and expansive soil anchor grouting plugs.

[0007] The patent document with the authorization announcement number "CN202039360U" and the name "Anchor Cable Grouting Plug" discloses a grouting plug for anchor cables. "A silicone plate is sandwiched between two PVC plates with higher hardness. The two PVC plates and the silicone plate are fixed with screws to form a disc-shaped plug body. Circular reserved holes for passing grouting pipes, exhaust pipes and steel strands are symmetrically arranged on the disc-shaped plug body. The disc-shaped plug body is placed on the anchor cable and fixed. There are PVC plate anchor cable steel strand reserved holes, PVC plate grouting pipe reserved holes and PVC plate exhaust pipe reserved holes on the PVC plate. There are silicone plate anchor cable steel strand reserved holes, silicone plate grouting pipe reserved holes and silicone plate exhaust pipe reserved holes on the silicone plate. "When in use, the disc-shaped plug body is sent into the hole along with the anchor cable, and the silicone plate exposed from the PVC plate is flipped outward and attached to the wall of the drilled hole to achieve the grouting stop function. However, this type of grouting anchor has the following shortcomings: in actual working conditions, the wall of the anchor hole is not smooth, but rough and uneven. In order to ensure the sealing effect of the grouting plug, the outer diameter of the silicone plate is 20-30mm larger than the diameter of the anchor hole. When installing the anchor, the silicone plate has great friction with the rough hole wall, which can easily cause the grouting plug to be stuck by the residual rock in the hole, making it difficult to install the anchor. In severe cases, the grouting plug will be displaced, and the grouting length will not meet the predetermined requirements, or even the silicone plate will be damaged and unable to play the grouting role.

[0008] The patent document with the authorization announcement number "CN104164874B" and the name "Construction method of anchor structure using expansive soil anchor grouting plug" discloses an expansive soil anchor grouting plug and an anchor structure and construction method using the same. "The expansive soil anchor grouting plug includes a centering bracket, a steel strand, a high-pressure grouting pipe and expansive soil. The expansive soil is wrapped with a flexible material and wound between each of the steel strands. The high-pressure grouting pipe passes through the expansive soil. The centering bracket is arranged at both ends of the expansive soil anchor grouting plug." When in use, expansive soil with strong expansion properties is used as the raw material, and a layer of geotextile or non-woven fabric is wrapped around the outer periphery of the raw material. After the expansive soil anchor grouting plug swells when exposed to water, it will generate a strong axial force with the hole wall, making the contact between the expansive soil anchor grouting plug and the hole wall closer. However, this type of grouting structure has the following shortcomings: 1) The preparation and filling of expansive soil is cumbersome, requiring steps such as rolling, drying, and screening before being filled into flexible bags in proportion; 2) The flexible bags containing expansive soil need to be manually wrapped between the individual steel strands, resulting in low anchor cable production efficiency. Furthermore, the binding method and installation position are subject to human uncontrollable factors, making it difficult to achieve unified and standardized installation and production.

[0009] 3) The flexible material containing expansive soil wrapped around the steel strand is easily damaged by friction with the rough hole wall during the installation of the anchor cable, and the expansive soil leaks, affecting the grouting effect.

[0010] Therefore, the existing anchor cable grouting structure and grouting method still need to be improved. Summary of the invention:

[0011] The first object of the present invention is to provide a compact automatic grouting device for downward-pointing anchor cables.

[0012] The second object of the present invention is to provide a downward-leaning anchor cable equipped with an automatic grouting stop device, which has an automatic grouting stop function, a compact structure, is easy to use, and is highly efficient.

[0013] The third object of the present invention is to provide a grouting method using the downward-pointing anchor cable provided with an automatic grouting stopping device, which can accurately and effectively control the length of the anchoring section.

[0014] The first purpose of the present invention is implemented by the following technical solution: an automatic grouting device for a downward-lying anchor cable, which includes a casing, in which an inlet annular baffle and an outlet annular baffle are provided; the outer annular surface of the inlet annular baffle is fitted and fixedly connected to the inner wall of the casing; the outer annular surface of the outlet annular baffle is fitted and fixedly connected to the inner wall of the casing; a valve plate for cooperating with the inlet annular baffle is provided between the inlet annular baffle and the outlet annular baffle, a spring is provided between the valve plate and the outlet annular baffle, one end of the spring is fixedly connected to the outlet annular baffle, and the other end of the spring is fixedly connected to the valve plate, and the valve plate is tightly fitted and connected to the inlet annular baffle under the elastic force of the spring.

[0015] Furthermore, the automatic grouting stopping device for the downward-lying anchor cable further includes a guide rod, which passes through the annular baffle at the inlet end and is fixedly connected to the valve plate.

[0016] Furthermore, one end of the guide rod connected to the valve plate passes through the valve plate and extends along the axial direction of the spring to the inside of the spring.

[0017] Furthermore, the sleeve includes an upper sleeve and a lower sleeve, the outer ring surface of the annular baffle at the inlet end is fitted and fixedly connected to the inner wall of the upper sleeve; the outer ring surface of the annular baffle at the outlet end is fitted and fixedly connected to the inner wall of the lower sleeve; it also includes an annular connecting piece, and the outlet end of the upper sleeve and the inlet end of the lower sleeve are fixedly connected via the annular connecting piece.

[0018] Furthermore, the outlet end of the annular connector is provided with a slot, and the inlet end of the lower sleeve is provided with a boss matching the slot; the boss is snapped into the slot; the inlet end of the annular connector is threadedly connected to the outlet end of the upper sleeve.

[0019] The second purpose of the present invention is implemented by the following technical solutions: a downward-facing anchor cable provided with an automatic grouting-stopping device, which includes a steel strand, an anchor head, an anchor pier and a grouting pipe, and also includes an automatic grouting-stopping device, the automatic grouting-stopping device includes a casing, an inlet annular baffle and an outlet annular baffle are provided in the casing; the outer annular surface of the inlet annular baffle is fitted and fixedly connected to the inner wall of the casing; the outer annular surface of the outlet annular baffle is fitted and fixedly connected to the inner wall of the casing; a valve plate for cooperating with the inlet annular baffle is provided between the inlet annular baffle and the outlet annular baffle, and the valve plate is connected to the outlet annular baffle A spring is provided between the annular baffles, one end of the spring is fixedly connected to the annular baffle at the outlet end, and the other end of the spring is fixedly connected to the valve plate. The valve plate is tightly fitted and connected to the annular baffle at the inlet end under the elastic force of the spring; the grouting pipe comprises an upper grouting pipe and a lower grouting pipe, the outlet end of the upper grouting pipe is sleeve-fixed connected or butt-fixed connected or butt-jointed and integrally formed with the inlet end of the casing; the outlet end of the casing is sleeve-fixed connected or butt-fixed connected or butt-jointed and integrally formed with the inlet end of the lower grouting pipe; the distance from the center point of the valve plate to the bottom of the anchor hole is a, and 0<a<R, R is the length of the anchoring section.

[0020] Furthermore, the automatic slurry stopping device also includes a guide rod, which passes through the annular baffle at the inlet end and is fixedly connected to the valve plate.

[0021] Furthermore, one end of the guide rod connected to the valve plate passes through the valve plate and extends along the axial direction of the spring to the inside of the spring.

[0022] Furthermore, the casing includes an upper casing and a lower casing, the outlet end of the upper grouting pipe is sleeve-fixedly connected or butt-fixedly connected or butt-jointed to form an integral whole with the inlet end of the upper casing; the outlet end of the lower casing is sleeve-fixedly connected or butt-fixedly connected or butt-jointed to form an integral whole with the inlet end of the lower grouting pipe; the outer annular surface of the annular baffle at the inlet end is fit-fitted and fixedly connected to the inner wall of the upper casing; the outer annular surface of the annular baffle at the outlet end is fit-fitted and fixedly connected to the inner wall of the lower casing; it also includes an annular connector, and the outlet end of the upper casing and the inlet end of the lower casing are fixedly connected via the annular connector.

[0023] Furthermore, the outlet end of the annular connector is provided with a slot, and the inlet end of the lower sleeve is provided with a boss matching the slot; the boss is snapped into the slot; the inlet end of the annular connector is threadedly connected to the outlet end of the upper sleeve.

[0024] The third object of the present invention is implemented by the following technical solution: a grouting method for a downward-facing anchor cable equipped with an automatic grouting stop device, comprising the following steps: S1. preparing cement material by batching; S2. mixing water and cement material in proportion to prepare cement slurry; S3. primary grouting; S4. secondary grouting; wherein the step S3. primary grouting includes: (1) overpressure grouting; (2) constant pressure grouting;

[0025] The step (1) of overpressure grouting is to insert the downward-facing anchor cable provided with the automatic grouting stop device into the anchor cable hole, and adjust the grouting pressure of the grouting pump to 8-10 times of the constant pressure grouting pressure Q. Times, the cement slurry prepared in the S2. slurrying step is injected into the upper grouting pipe through the grouting pump and hits the valve plate. At this time, the upper surface of the valve plate is subjected to the pumping pressure F1 of the grouting pump and the gravity component G1 of the cement slurry's own gravity in the grouting pipe above the valve plate along the axial direction of the grouting pipe, and the lower surface of the valve plate is subjected to the spring force F2. The spring force F2 applied to the valve plate is less than the sum of F1 and G1. The spring is further compressed, driving the valve plate to move downward along the axial direction of the grouting pipe under the action of F1 and G1. The valve plate is separated from the annular baffle at the inlet end to form a liquid inlet, and the cement slurry is driven into the lower grouting pipe along the liquid inlet, and then into the anchor hole; until the volume of the cement slurry injected into the anchor hole reaches the designed volume, and the overpressure grouting is completed; since the spring still has a certain length after being compressed to the limit, it can be ensured that the device is always in a connected state during the entire overpressure grouting process. Overpressure grouting is used to spray the slurry into the cracks in the hole wall of the anchor section to prevent leakage, increase the density of the slurry in the anchor section and enhance the anchoring performance.

[0026] The step (2) is constant pressure grouting: the grouting pressure of the grouting pump is adjusted to the constant pressure grouting pressure Q, and constant pressure grouting is performed. At this time, the resultant force acting on the upper surface of the valve plate is the constant pressure grouting pressure F1 and G1; when the cement slurry in the anchor hole is higher than the valve plate, the component force of the cement slurry's own gravity above the valve plate along the axial direction of the grouting pipe is G2, and G2 and the spring force F2 act together on the lower surface of the valve plate. During the continuous grouting process, G2 increases continuously until F1+G1=F2+G2. Thereafter, the valve plate is in a dynamic force equilibrium state at any time, and F1+G1=F2+G2, that is, during the continuous grouting process, G2 increases continuously, and F2 increases with G2. It increases continuously and decreases accordingly, and the increase value of G2 is equal to the decrease value of F2. The spring is gradually released to drive the valve plate to move upward along the axial direction of the grouting pipe until F2 is reduced to the initial design value. The valve plate is tightly fitted with the annular baffle at the inlet end. At this time, the grouting flow of the grouting pump is zero, the automatic grouting stop device completes the automatic grouting, and the constant pressure grouting ends; at this time, the length of the anchoring section just reaches the design value R, realizing precise control of the length of the anchoring section.

[0027] The calculation formula of the constant pressure grouting pressure Q is as follows:

[0028]

[0029] Where: Q is the constant pressure grouting pressure (kPa), A is the valve plate surface area (m 2 ), k is the spring constant (kN / m), x is the initial design compression of the spring (m), ρ is the density of the cement slurry (t / m 3 ), g is the gravity coefficient (N / kg), L is the length of the anchor cable (m), R is the length of the anchoring section (m), α is the angle between the axial direction of the anchor cable hole and the horizontal plane, unit: °;

[0030] S4. Secondary grouting: When the cement slurry in the anchor hole solidifies to a slurry solidification strength that is at least equal to that reached 8 days after the first grouting, the anchor cable is tensioned, and after the anchor head is locked by the anchor pier, the grouting pump is connected to the secondary grouting hole on the anchor pier, and secondary grouting is performed according to the constant pressure grouting pressure Q. When the cement slurry overflows from the orifice of the anchor hole, the process stops, and the secondary grouting is completed.

[0031] Furthermore, in the step (1) of overpressure grouting, the volume of cement slurry injected into the anchor hole is 1 / 4 of the volume D0 of the anchoring section of the anchor hole. Times, wherein the calculation formula of D0 is as follows:

[0032]

[0033] Where D0 is the volume of the anchor hole in the anchoring section (m 3 ), d is the diameter of the anchor hole (m), and R is the length of the anchoring section (m).

[0034] Derivation process of constant pressure grouting pressure Q:

[0035] During the constant pressure grouting process, the valve plate is taken as the research object, such as Figure 5 As shown, the upper surface of the valve plate is subjected to the pumping pressure F1 of the grouting pump and the gravity component G1 of the cement slurry's own gravity along the axial direction of the grouting pipe above the valve plate. The lower surface of the valve plate is subjected to the spring force F2 and the gravity component G2 of the cement slurry's own gravity in the anchor hole above the valve plate along the axial direction of the grouting pipe.

[0036] During the constant pressure grouting process, when the valve plate is in a dynamic force equilibrium state at any time, as shown in formula (1):

[0037] F1+G1=F2+G2 (1)

[0038] The directions of F1 and G1 are pointing to and perpendicular to the upper surface of the valve plate, and the directions of F2 and G2 are pointing to and perpendicular to the lower surface of the valve plate;

[0039] When the valve plate is in close contact with the annular baffle at the inlet end, that is, when the valve plate is in the slurry stopping state, in formula (1):

[0040] F1=QA (2)

[0041] G1=ρgA(La)sinα (3)

[0042] F2=kx (4)

[0043] G2=ρgA(Ra)sinα (5)

[0044] Substituting equations (2)-(5) into equation (1) yields equation (6):

[0045] QA+ρgA(La)sinα=kx+ρgA(Ra)sinα (6)

[0046] Formula (7) can be further obtained by transforming formula (6):

[0047] QA+ρgALsinα=kx+ρgARsinα (7)

[0048] Formula (7) is further transformed to obtain formula (8):

[0049]

[0050] In formulas (2)-(8), Q is the constant pressure grouting pressure (kPa), A is the valve plate surface area (m 2 ), k is the spring constant (kN / m), x is the initial design compression of the spring (m), ρ is the density of the cement slurry (t / m 3 ), g is the gravity coefficient (N / kg), L is the length of the anchor cable (m), R is the length of the anchoring section (m), α is the inclination angle of the axial direction of the anchor hole relative to the horizontal plane, unit: °, and a is the distance from the center point of the valve plate to the bottom of the anchor hole when the valve plate is in the slurry stopping state (m).

[0051] The size of F1 is positively correlated with the grouting pressure of the grouting pump and the area of ​​the valve plate. The area of ​​the valve plate is a constant value. During the constant pressure grouting process, the size and direction of F1 remain unchanged because the grouting pressure of the grouting pump remains unchanged.

[0052] The size of G1 is positively correlated with the straight-line distance from the orifice of the grouting pipe to the upper surface of the valve plate, the density of the cement slurry, the area of ​​the valve plate surface, and the sine value of the inclination angle of the grouting pipe relative to the horizontal plane. The displacement of the valve plate during constant-pressure grouting is negligible compared with the straight-line distance from the orifice of the grouting pipe to the upper surface of the valve plate. It can be assumed that the straight-line distance from the orifice of the grouting pipe to the upper surface of the valve plate remains unchanged. Under the premise that the density of the cement slurry and the area of ​​the valve plate surface are constant, the size and direction of G1 also remain unchanged.

[0053] The size of F2 is positively correlated with the spring's stiffness coefficient and compression amount. After the spring is selected, the spring's progress coefficient remains unchanged.

[0054] During the entire constant pressure grouting process, the grouting pressure of the grouting pump is adjusted to the constant pressure grouting pressure Q, and constant pressure grouting is performed. At this time, the resultant force acting on the upper surface of the valve plate is the constant pressure grouting pressure F1 and G1; when the cement slurry in the anchor hole is higher than the valve plate, the component force of the cement slurry's own gravity above the valve plate along the axial direction of the grouting pipe is G2, and G2 and the spring force F2 act together on the lower surface of the valve plate. F2 and G2 are variable forces, with changing magnitudes but unchanged directions. As the cement slurry in the anchor hole rises, G2 gradually increases from zero. When F1+G1=F2+G2 When the spring is released, the valve plate is in a dynamic force equilibrium state at any time, and F1+G1=F2+G2, that is, F2 decreases accordingly with the increase of G2, and the increase value of G2 is equal to the decrease value of F2. The spring is released to drive the valve plate to gradually move upward along the grouting pipe; until the cement slurry level in the anchor hole reaches a predetermined height, that is, the length of the anchoring section, F2 decreases to the initial set value, and the spring is released to the initial design compression amount to drive the valve plate to return to the initial position to close the grouting channel. The slurry at the injection end cannot continue to flow in, so as to achieve the purpose of automatic slurry stopping.

[0055] Advantages of the present invention:

[0056] (1) The present invention provides a downward-facing anchor cable and grouting method equipped with an automatic grouting stop device. The grouting process can effectively control the length of the anchoring section and accurately distinguish the anchoring section from the free section. When the grouting liquid length reaches the designed value of the anchoring section length, the grouting pipe can be automatically blocked immediately to avoid excessive injection of slurry in the anchoring section, thereby ensuring construction requirements and reducing raw material costs.

[0057] (2) It overcomes the requirement of existing anchor cable structure for the flatness of the hole wall. The automatic grouting device is installed on the grouting pipe wrapped by the steel strand. When the anchor cable is installed, the automatic grouting device does not contact the hole wall of the anchor cable hole, thereby avoiding the friction and blocking problems between the automatic grouting device and the hole wall of the anchor cable hole, and can achieve smooth installation of the anchor cable and improve installation efficiency. At the same time, it effectively prevents the rough hole wall from wearing and damaging the automatic grouting device during the installation of the anchor cable, and is safe and reliable.

[0058] (3) The automatic grouting device has a simple overall structure, light weight, strong strength and low cost; the downward-facing anchor cable equipped with the automatic grouting device has a compact structure and is easy to use, which improves the convenience of anchor cable production, storage, installation and other construction, and has a wide range of applications; it is no longer necessary to set up a long exhaust pipe separately, which reduces engineering costs and improves construction efficiency;

[0059] (4) The entire grouting process is divided into primary grouting and secondary grouting. The primary grouting is divided into two stages: overpressure grouting and constant pressure grouting. Overpressure grouting can not only spray the slurry into the cracks in the anchoring section through the high pressure during grouting to prevent leakage, but also improve the density of the slurry in the anchoring section, thereby enhancing the anchoring performance. Constant pressure grouting can give full play to the automatic sealing of the grouting pipe, and has achieved relatively accurate control of the length of the anchoring section.

[0060] (5) The secondary grouting separates the prestressed steel strands from the air, greatly reducing the probability of the free section anchor cable steel strands failing due to strength reduction caused by oxidation. Description of the drawings:

[0061] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, 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.

[0062] Figure 1 This is a schematic diagram of an automatic grouting device for a downward-facing anchor cable in Example 1.

[0063] Figure 2 This is a partial schematic diagram of the downward-facing anchor cable provided with an automatic grouting stop device in Example 2.

[0064] Figure 3 This is a schematic diagram of the use of the downward-facing anchor cable provided with an automatic grouting stop device according to Example 2;

[0065] Figure 4 for Figure 3 The cross-sectional view of the AA surface shown in FIG;

[0066] Figure 5 for Figure 3 A cross-sectional view of the BB surface shown in FIG;

[0067] Figure 6 This is the force analysis diagram of the valve plate;

[0068] Figure 7 Schematic diagram of various parameters for calculating constant pressure grouting pressure Q;

[0069] Figure 8 for Figure 7 Schematic diagram of the parameters.

[0070] In the figure, steel strand 1, anchor head 2, binding wire 3, isolation frame 4, guide cap 5, grouting pipe 6, upper grouting pipe 6.1, lower grouting pipe 6.2, automatic grouting stop device 7, anchor cable hole 8, anchor pier 9, secondary grouting hole 10, upper casing 11, lower casing 12, inlet end annular baffle 13, spring 14, valve plate 15, guide rod 16, annular connector 17, outlet end annular baffle 18, slot 19, boss 20. Specific implementation method:

[0071] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0072] Example 1: Figure 1 As shown, an automatic grouting device for a downward-lying anchor cable includes a casing, in which an inlet annular baffle 13 and an outlet annular baffle 18 are provided; the outer annular surface of the inlet annular baffle 13 is fitted and fixedly connected to the inner wall of the casing; the outer annular surface of the outlet annular baffle 18 is fitted and fixedly connected to the inner wall of the casing; a valve plate 15 for cooperating with the inlet annular baffle 13 is provided between the inlet annular baffle 13 and the outlet annular baffle 18, a spring 14 is provided between the valve plate 15 and the outlet annular baffle 18, one end of the spring 14 is fixedly connected to the outlet annular baffle 18, and the other end of the spring 14 is fixedly connected to the valve plate 15, and the valve plate 15 is tightly fitted and connected to the inlet annular baffle 13 under the elastic force of the spring 14.

[0073] In a specific embodiment, a guide rod 16 is further included. The guide rod 16 passes through the inlet end annular baffle 13 and is fixedly connected to the valve plate 15 .

[0074] In a specific embodiment, one end of the guide rod 16 connected to the valve plate 15 passes through the valve plate 15 and extends along the axial direction of the spring 14 to the inside of the spring 14 .

[0075] In a specific embodiment, the sleeve includes an upper sleeve 11 and a lower sleeve 12, and the outer ring surface of the annular baffle 13 at the inlet end is fitted and fixedly connected to the inner wall of the upper sleeve 11; the outer ring surface of the annular baffle 18 at the outlet end is fitted and fixedly connected to the inner wall of the lower sleeve 12; it also includes an annular connector 17, and the outlet end of the upper sleeve 11 and the inlet end of the lower sleeve 12 are fixedly connected via the annular connector 17.

[0076] In a specific embodiment, the outlet end of the annular connector 17 is provided with a slot 19, and the inlet end of the lower sleeve 12 is provided with a boss 20 matching the slot 19; the boss 20 is snapped into the slot 19; the inlet end of the annular connector 17 is threadedly connected to the outlet end of the upper sleeve 11.

[0077] Example 2: Figure 2-5 As shown, a downward-prone anchor cable is provided with an automatic grouting-stopping device, which includes a cable body, an anchor head 2, and an anchor pier 9. The cable body includes a steel strand 1 and a grouting pipe 6. In this embodiment, the anchor cable is designed to be 30m long. The cable body runs through the entire anchor cable. The material consists of bundles of steel strands 1 with a diameter of 15.2mm and a tensile strength of 1860MPa and a PVC grouting pipe 6 with a diameter of 33mm. Each bundle of steel strands 1 is evenly distributed along the circumference through an isolation frame 4 and wraps the grouting pipe 6 in the center.

[0078] The anchoring section includes a guide cap 5, spacers 4, and an automatic grouting stop 7. The guide cap 5 is secured to the front of the cable body with lead wire, maintaining a distance of 19 to 21 cm from the bottom of the hole. Spacers 4 are installed starting 50 cm from the front of the cable body. Additional spacers 4 are added every 150 cm from the previous spacer 4, until the final spacer 4 is within 150 cm of the anchoring section. Galvanized iron binding wire 3 is used to secure the strands 1 at their midpoints until the anchoring section ends. The spacers 4 spread the steel strands, evenly distributing them and ensuring that the cement slurry is fully coupled to the strands during grouting. The automatic grouting stop 7 is installed by gluing or hot-melting at a distance a from the front of the cable body. The valve plate 15 of the automatic grouting stop 7 is 85 cm from the bottom of the anchor hole. After the rebar in the free section is evenly coated with butter, each bundle is sequentially threaded through a 20 mm diameter electrical insulating sleeve. Galvanized iron binding wire 3 is used to tie every 150 cm from the beginning of the free section to the end of the free section to prevent the front structure from being damaged by the rough rock wall when installing the anchor cable, and to improve the efficiency of anchor cable installation. The anchor pier 9 is cast in one go by C30 fine-grained concrete, and secondary grouting holes 10, spiral reinforcements, steel pads and other components are pre-buried inside. The centers of the spiral reinforcements and steel pads are aligned with the centers of the orifices in turn, and the cable body passes through and extends at least 30 cm. The secondary grouting hole 10 connects the outside to the anchor cable hole and forms an angle of 35 degrees with the horizontal plane. The anchor is placed on the outer surface of the anchor pier 9 to maintain the prestress of the anchor cable when the anchor cable is tensioned.

[0079] The binding method involved in this embodiment is to wrap the galvanized iron binding wire around the steel strands orthogonally for 3 turns and twist them counterclockwise for 8 turns. After the binding is completed, the excess binding wire is cut off. The grouting pipe 6 in this embodiment includes an upper grouting pipe 6.1 and a lower grouting pipe 6.2.

[0080] The automatic slurry stopping device 7 of this embodiment includes a sleeve, in which an inlet annular baffle 13 and an outlet annular baffle 18 are provided; a valve plate 15 for cooperating with the inlet annular baffle 13 is provided between the inlet annular baffle 13 and the outlet annular baffle 18, and a spring 14 is provided between the valve plate 15 and the outlet annular baffle 18, one end of the spring 14 is fixedly connected to the outlet annular baffle 13, and the other end of the spring 14 is fixedly connected to the valve plate 15, and the valve plate 15 is tightly fitted and connected to the inlet annular baffle 13 under the elastic force of the spring 14; in this embodiment, an annular sealing rubber gasket is also provided between the valve plate 15 and the inlet annular baffle 13; the distance from the center point of the valve plate 15 to the bottom of the anchor hole is a, and 0<a<R, R is the length of the anchoring section, and a is 85cm in this embodiment.

[0081] The casing includes an upper casing 11 and a lower casing 12. The outlet end of the upper grouting pipe 6.1 is fixedly connected to the inlet end of the upper casing 11 by sleeve connection. The outlet end of the lower casing 12 is fixedly connected to the inlet end of the lower grouting pipe 6.2 by sleeve connection. The outer ring surface of the inlet end annular baffle 13 is fixedly connected to the inner wall of the upper casing 11. The outer ring surface of the outlet end annular baffle 18 is fixedly connected to the inner wall of the lower casing 12. It also includes an annular connector 17. The outlet end of the annular connector 17 is provided with a slot 19. The inlet end of the lower casing 12 is provided with a boss 20 matching the slot 19. The boss 20 is engaged in the slot 19. The inlet end of the annular connector 17 is threadedly connected to the outlet end of the upper casing 11. The annular connector has two functions: 1) it reduces the manufacturing complexity of the entire component and facilitates the installation of the spring, cover plate and guide rod; 2) it facilitates the replacement of damaged parts inside the component and improves the maintenance convenience of the entire component; 3) it improves the sealing performance and overall stability of the device.

[0082] The automatic grouting device 7 further comprises a guide rod 16, which passes through the inlet annular baffle 13 and is fixedly connected to the valve plate 15. The guide rod can ensure that the cover plate can only move in one dimension along the grouting direction during the entire process.

[0083] One end of the guide rod 16 connected to the valve plate 15 passes through the valve plate 15 and extends axially to the inside of the spring 14 , ensuring that the cover plate can only move in one dimension along the grouting direction during the entire process.

[0084] Example 3: Figure 2-8 As shown, the grouting method of the downward-facing anchor cable provided with the automatic grouting stop device using Example 2 includes the following steps: S1. preparing cement material by batching; S2. preparing cement slurry by mixing water and cement material in proportion; S3. primary grouting; S4. secondary grouting;

[0085] S1. Prepare cement material by mixing ingredients: Use a shovel or solid mixer to thoroughly mix cement, cement pumping agent, and sodium silicate powder in a mass ratio of 1:0.3:0.05-0.1. The cement can be one or more of PO42.5, PS42.5, PF42.5R, or PC42.5. In this embodiment, PO42.5 cement is used, and the mass ratio of PO42.5 cement, cement pumping agent, and sodium silicate powder is 1:0.3:0.05. This mixture improves the physical properties of the cement slurry while maintaining the required strength after setting, enhancing its fluidity and anti-sedimentation properties. When used in this embodiment, it can achieve the designed function of automatically sealing the grouting pipe and effectively controlling the length of the anchoring section. The cement pumping agent in this embodiment can be replaced with a water reducer. The water reducer can perform the same function as the cement pumping agent and is added in an amount of 0.5 times the mass of the cement to improve the physical properties of the cement slurry, enhancing its fluidity and anti-sedimentation properties.

[0086] S2. Mix water and cement in proportion to prepare cement slurry: Pure water and the cement mixed in the first step are mixed in a mass ratio of 1:1 and stirred for a predetermined period of time to form a cement slurry. The stirring time should be no less than 5 minutes and no more than 15 minutes. The purpose is to fully mix the mixed cement and water and allow the slurry to cool and stabilize to room temperature. Stirring for less than 5 minutes will result in insufficient stirring and a high cement slurry temperature. Stirring for more than 15 minutes will cause the cement slurry to segregate and become ineffective.

[0087] S3. One-time grouting includes: (1) overpressure grouting; (2) constant pressure grouting;

[0088] Step (1) overpressure grouting: after the on-site anchor hole construction is completed, the downward-facing anchor cable provided with the automatic grouting stop device in Example 2 is inserted into the anchor cable hole 8, and the grouting pressure of the grouting pump is adjusted to 10 times the constant pressure grouting pressure Q. The cement slurry prepared in the grouting step S2 is injected into the upper grouting pipe 6.1 through the grouting pump and hits the valve plate 15. At this time, the upper surface of the valve plate 15 is subjected to the pumping pressure F1 of the grouting pump and the gravity of the cement slurry in the grouting pipe 6 above the valve plate 15 along the axial direction of the grouting pipe. Gravity component G1, the lower surface of the valve plate 15 is subjected to the spring force F2, the spring force F2 on the valve plate 15 is less than the sum of F1 and G1, the spring is further compressed, driving the valve plate 15 to move downward along the axial direction of the grouting pipe, the valve plate 15 is separated from the annular baffle 13 at the inlet end to form a liquid inlet, and the cement slurry is injected into the lower grouting pipe 6.2 along the liquid inlet, and then into the anchor hole 8; until the volume of cement slurry injected into the anchor hole 8 reaches the set volume, the overpressure grouting is completed; in this embodiment, the volume of cement slurry injected into the anchor hole 8 is d is the diameter of the anchor hole, 150 mm, R is the length of the anchor section, 10 m, and the volume of cement slurry injected into the anchor hole 8 is calculated as Overpressure grouting is used to spray the slurry into the cracks in the hole wall of the anchor section to prevent leakage, increase the density of the slurry in the anchor section and enhance the anchoring performance.

[0089] Step (2) constant pressure grouting: adjust the grouting pressure of the grouting pump to the constant pressure grouting pressure Q, and perform constant pressure grouting. At this time, the resultant force acting on the upper surface of the valve plate 15 is the constant pressure grouting pressure F1 and G1; when the cement slurry in the anchor hole 8 is higher than the valve plate 15, the component force of the cement slurry's own gravity above the valve plate 15 along the axial direction of the grouting pipe is G2, and G2 and the spring force F2 act together on the lower surface of the valve plate 15. During the continuous grouting process, G2 continues to increase. When F1+G1=F2+G2, thereafter, the valve plate 15 is in a dynamic force equilibrium state at any time, and F1+G1=F2+G2, that is, during the continuous grouting process, G2 continues to increase, and F2 increases with G2. It increases continuously and decreases accordingly, and the increase value of G2 is equal to the decrease value of F2. The spring 14 is gradually released to drive the valve plate 15 to move upward along the grouting pipe 6 until F2 is reduced to the initial design value. The valve plate 15 fits tightly with the annular baffle 13 at the inlet end. At this time, the grouting flow of the grouting pump is zero, the automatic grouting stop device completes the automatic grouting, and the constant pressure grouting ends. At this time, the length of the anchoring section just reaches the design value R, realizing precise control of the length of the anchoring section.

[0090] Among them, the calculation formula of constant pressure grouting pressure Q is as follows:

[0091]

[0092] Where: Q is the constant pressure grouting pressure (kPa), A is the valve plate surface area (m 2 ), k is the spring constant (kN / m), x is the initial design compression of the spring (m), ρ is the density of the cement slurry (t / m 3 ), g is the gravity coefficient (N / kg), L is the length of the anchor cable (m), R is the length of the anchor section (m), and α is the angle between the axial direction of the anchor cable hole and the horizontal plane, in degrees.

[0093] In this embodiment, A is 706.5 mm 2 , k is 1.5 kN / m, x is 6 cm, ρ is 1.5 t / m 3 , g is 10m / s 2 , L is 30m, R is 10m, α is 15°; Substitute the above values ​​into the following formula

[0094]

[0095] for

[0096] S4. Secondary grouting: When the cement slurry in the anchor hole 8 solidifies to a slurry solidification strength that is at least equal to that reached 8 days after the first grouting, in this embodiment, 10 days after the first grouting, the anchor cable is tensioned, and after the anchor head 2 is locked by the anchor pier 9, the grouting pump is connected to the secondary grouting hole 10 on the anchor pier 9, and secondary grouting is performed according to the constant grouting pressure Q. When the cement slurry overflows from the orifice of the anchor hole 8, the secondary grouting is stopped, and the grouting process is completed.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Grouting method using a downward-facing anchor cable equipped with an automatic grouting stop device, characterized in that: The method comprises the following steps: S1. preparing cement material by mixing ingredients; S2. preparing cement slurry by mixing water and cement material in proportion; S3. grouting once; S4. Secondary grouting; wherein, the step S3. Primary grouting includes: (1) overpressure grouting; (2) constant pressure grouting; The downward-lying anchor cable is provided with an automatic grouting-stopping device, comprising a steel strand, an anchor head, an anchor pier and a grouting pipe, and further comprising an automatic grouting-stopping device, wherein the automatic grouting-stopping device comprises a casing, wherein an inlet annular baffle and an outlet annular baffle are provided in the casing; the outer annular surface of the inlet annular baffle is fitted and fixedly connected to the inner wall of the casing; the outer annular surface of the outlet annular baffle is fitted and fixedly connected to the inner wall of the casing; a valve plate for cooperating with the inlet annular baffle is provided between the inlet annular baffle and the outlet annular baffle, and a spring is provided between the valve plate and the outlet annular baffle, One end of the spring is fixedly connected to the annular baffle at the outlet end, and the other end of the spring is fixedly connected to the valve plate. The valve plate is tightly connected to the annular baffle at the inlet end under the elastic force of the spring; the grouting pipe includes an upper grouting pipe and a lower grouting pipe, and the outlet end of the upper grouting pipe is sleeve-fixed connected or butt-fixed connected or butt-jointed and integrally formed with the inlet end of the casing; the outlet end of the casing is sleeve-fixed connected or butt-fixed connected or butt-jointed and integrally formed with the inlet end of the lower grouting pipe; the distance from the center point of the valve plate to the bottom of the anchor hole is a, and 0<a<R, R is the length of the anchoring section; The step (1) of overpressure grouting is as follows: insert the downward-facing anchor cable provided with the automatic grouting stop device into the anchor cable hole, adjust the grouting pressure of the grouting pump to 8-10 times of the constant pressure grouting pressure Q, and inject the cement slurry obtained in the grouting step S2 into the upper grouting pipe through the grouting pump, and hit the valve plate. At this time, the upper surface of the valve plate is subjected to the pumping pressure F1 of the grouting pump and the gravity of the cement slurry in the grouting pipe above the valve plate along the axial direction of the grouting pipe. Gravity component G1, the lower surface of the valve plate is subjected to spring force F2, the spring force F2 on the valve plate is smaller than the sum of F1 and G1, the spring is further compressed, driving the valve plate to move downward along the axial direction of the grouting pipe under the action of F1 and G1, the valve plate is separated from the annular baffle at the inlet end to form a liquid inlet, and cement slurry is injected into the lower grouting pipe along the liquid inlet, and then into the anchor hole; until the volume of cement slurry injected into the anchor hole reaches the designed volume, the overpressure grouting is completed; The step (2) is constant pressure grouting: the grouting pressure of the grouting pump is adjusted to the constant pressure grouting pressure Q, and constant pressure grouting is performed. At this time, the resultant force acting on the upper surface of the valve plate is the constant pressure grouting pressure F1 and G1; when the cement slurry in the anchor hole is higher than the valve plate, the component force of the cement slurry's own gravity above the valve plate along the axial direction of the grouting pipe is G2, and G2 and the spring elastic force F2 act together on the lower surface of the valve plate. During the continuous grouting process, G2 increases continuously until F1+G1=F2+G2. After that, the valve The plate is in a dynamic force equilibrium state at any time, and F1+G1=F2+G2, that is, G2 increases continuously during the grouting process, and F2 decreases accordingly as G2 increases continuously, and the increase value of G2 is equal to the decrease value of F2. The spring is gradually released to drive the valve plate to move upward along the axial direction of the grouting pipe until F2 decreases to the initial design value. The valve plate is tightly fitted with the annular baffle at the inlet end. At this time, the grouting flow of the grouting pump is zero, the automatic grouting stop device completes the automatic grouting, and the constant pressure grouting ends; The calculation formula of the constant pressure grouting pressure Q is as follows: Where: Q is the constant pressure grouting pressure, unit is kPa; A is the valve plate surface area, unit is m 2 ; k is the spring constant, in kN / m; x is the initial design compression of the spring, in m; ρ is the density of the cement slurry, in t / m 3 ; g is the gravity coefficient, unit is N / kg; L is the length of the anchor cable, unit is m; R is the length of the anchor section, unit is m; α is the angle between the axial direction of the anchor cable hole and the horizontal plane, unit is °; S4. Secondary grouting: When the cement slurry in the anchor hole solidifies to a slurry solidification strength that is at least equal to that reached 8 days after the first grouting, the anchor cable is tensioned, and after the anchor head is locked by the anchor pier, the grouting pump is connected to the secondary grouting hole on the anchor pier, and secondary grouting is performed according to the constant pressure grouting pressure Q. When the cement slurry overflows from the orifice of the anchor hole, the process stops, and the secondary grouting is completed.

2. The grouting method according to claim 1, wherein In the step (1) of overpressure grouting, the volume of cement slurry injected into the anchor hole is equal to the volume D0 of the anchor section of the anchor hole. ~ Times, wherein the calculation formula of D0 is as follows: D0= Where D0 is the volume of the anchor hole in the anchoring section, in m 3 ; d is the diameter of the anchor hole, in m; R is the length of the anchoring section, in m.

3. The grouting method according to claim 1, wherein The automatic slurry stopping device also includes a guide rod, which passes through the inlet end annular baffle and is fixedly connected to the valve plate.

4. The grouting method according to claim 3, wherein: One end of the guide rod connected to the valve plate passes through the valve plate and extends to the inside of the spring along the axial direction of the spring.

5. The grouting method according to any one of claims 1 to 4, characterized in that: The casing includes an upper casing and a lower casing, the outlet end of the upper grouting pipe is sleeve-fixedly connected or butt-fixedly connected or butt-jointed to form an integral whole with the inlet end of the upper casing; the outlet end of the lower casing is sleeve-fixedly connected or butt-jointed to form an integral whole with the inlet end of the lower grouting pipe; the outer ring surface of the annular baffle at the inlet end is fitted and fixedly connected to the inner wall of the upper casing; the outer ring surface of the annular baffle at the outlet end is fitted and fixedly connected to the inner wall of the lower casing; it also includes an annular connector, and the outlet end of the upper casing and the inlet end of the lower casing are fixedly connected via the annular connector.

6. The grouting method according to claim 5, characterized in that: The outlet end of the annular connector is provided with a slot, and the inlet end of the lower sleeve is provided with a boss matching the slot; the boss is snapped into the slot; the inlet end of the annular connector is threadedly connected to the outlet end of the upper sleeve.

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