Soil nailing wall supporting system and construction method thereof

Abstract

The invention discloses a soil nailing wall supporting system and a construction method thereof, and relates to the technical field of supporting, the soil nailing wall supporting system comprises a reinforcing mesh, a concrete surface layer and a plurality of anchoring structures, each anchoring structure comprises an anchorage device and a GFRP rib, the anchorage device is installed at one end of the GFRP rib, a plurality of centering devices are arranged in the length direction of the GFRP rib at intervals, and the centering devices are used for being matched with anchor holes; the anchorage device comprises a tray structure and a pre-tightening coupling nut, the pre-tightening coupling nut is installed on one side of the tray structure, and the other side of the tray structure is used for being attached to a reinforcing mesh. And the concrete surface layer covers the reinforcing mesh and the anchorage devices. The anchorage device, the tray structure and the GFRP bars are matched with the reinforcing mesh and the concrete surface layer, so that a good supporting effect is formed; the overall structure is convenient to construct, and construction efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of support technology, and in particular to a soil nailing wall support system and its construction method. Background Technology

[0002] Soil nailing walls utilize the inherent strength of the soil and rock mass, reinforcing the soil through soil nails and a concrete surface layer. Their structure exhibits good flexibility, adapting to certain soil deformations, coordinating stress distribution, and generally meeting engineering requirements in terms of deformation control. While widely used, traditional soil nailing walls still present some challenges: traditional reinforced soil nails can create obstacles during later excavation, increasing excavation difficulty and processing costs; and when using new materials, such as GFRP reinforcement as soil nailing material, traditional welding alignment methods are unsuitable due to their difficulty in welding.

[0003] For example, the prior art discloses a glass fiber reinforced resin soil nailing wall support system, which includes multiple mounting heads and soil nails corresponding to the mounting heads and located in the soil slope. The soil nails are threaded onto mounting nuts, and multiple overflow holes are opened through the soil nails. This support system has a relatively complex clamping part and connecting components, and the construction process is relatively complicated. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a soil nailing wall support system and its construction method. Through anchors, tray structures, GFRP reinforcement in conjunction with steel mesh and concrete surface layer, a good support effect is achieved; the overall structure is easy to construct and improves construction efficiency.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, embodiments of the present invention provide a soil nailing wall support system, including a steel mesh, a concrete surface layer and multiple sets of anchoring structures. The anchoring structure includes anchors and GFRP bars. The anchors are installed at one end of the GFRP bars. Multiple centering devices are arranged at intervals along the length of the GFRP bars. The centering devices are used to cooperate with the anchor holes. The anchor includes a tray structure and a pre-tightening coupling nut, with the pre-tightening coupling nut installed on one side of the tray structure and the other side of the tray structure used to attach the reinforcing mesh; the concrete surface layer covers the reinforcing mesh and the anchor.

[0006] As a further implementation, multiple mounting holes are evenly spaced along the length of the tray structure, and a pre-tightening coupling nut is installed in each mounting hole.

[0007] As a further implementation, the pallet structure includes a connecting pallet and end pallets, the contact surface between adjacent connecting pallets is a stepped surface, and the end pallets are located at both ends of the connecting pallets.

[0008] As a further implementation, the pre-tightening coupling nut has a cylindrical section and a tapered section connected as one piece, and the mounting hole is a tapered hole adapted to the tapered section.

[0009] As a further implementation, the centering device includes a fixing ring and a fixing head installed inside the fixing ring, with the two fixing heads arranged opposite each other to clamp the GFRP reinforcement.

[0010] As a further implementation, one side of the fixing head is connected to the inner wall of the fixing ring via a connecting rod, and the other side has an arc-shaped groove with threads on the surface of the arc-shaped groove that are compatible with the GFRP reinforcement.

[0011] As a further implementation, the anchor is made of GFRP material.

[0012] Secondly, embodiments of the present invention also provide a construction method for a soil nailing wall support system, comprising: Multiple centering devices are fixed to the GFRP reinforcement at a set distance; then the GFRP reinforcement is placed into the anchor hole. Cement grout is injected into the bottom of the hole using a grouting pump; after grouting is completed, steel mesh is tied and the first concrete surface layer is sprayed. Then, the anchors are installed on the sections of the GFRP reinforcement bars that are exposed in the anchor holes. After all the anchors are installed, the second shotcrete layer is applied.

[0013] As a further implementation method, during grouting, the grouting pipe is first fixed to the rod body of the GFRP reinforcement; the grouting pipe is then inserted into the hole, and grouting begins from the bottom of the hole.

[0014] As a further implementation, the anchor is installed after the first shotcrete surface layer has been sprayed for a set time. The end plate is set at one end, and each connecting plate is installed in sequence, and finally the other end plate is installed; then the pre-tightening coupling nut is screwed in.

[0015] The beneficial effects of this invention are as follows: (1) The support system of the present invention includes a steel mesh, a concrete surface layer and multiple sets of anchoring structures. The anchoring structures include anchors and GFRP bars. The anchors are composed of a tray structure and a pre-tightening coupling nut, so that the pre-tightening coupling nut and GFRP bars are arranged in multiple rows and columns, which, together with the steel mesh and the concrete surface layer, form a good support effect.

[0016] (2) The tray structure of the present invention is segmented and spliced, and the contact surface is stepped. The anchor and the tray structure are fixed by GFRP bars and steel mesh, so that the anchor and steel mesh interact with each other, which can effectively increase the contact area with the concrete surface layer, thereby improving the anchoring force. In addition, the GFRP bars are equipped with multiple centering devices, which can ensure the installation accuracy of the GFRP bars in the anchor holes, facilitate construction, and effectively ensure the support effect and efficiency.

[0017] (3) During construction, the support system of the present invention first fixes multiple centering devices to the GFRP reinforcement at a set distance; then the GFRP reinforcement is placed into the anchor hole; after grouting is completed, the steel mesh is tied and the first shotcrete layer of concrete is sprayed; then the anchor is installed on the section of the GFRP reinforcement exposed in the anchor hole. After all the anchors are installed, the second shotcrete layer of concrete is sprayed. The first shotcrete layer of concrete can quickly seal the soil surface and provide initial protection for the steel mesh; after the anchors are installed, the second shotcrete layer of concrete can completely cover the anchors and the steel mesh, forming a continuous concrete layer and ensuring the construction effect. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0019] Figure 1 This is a cross-sectional view of the completed construction of the support system according to one or more embodiments of the present invention; Figure 2 This is a top view of the anchoring structure arrangement according to one or more embodiments of the present invention; Figure 3 This is a cross-sectional view of the anchor structure according to one or more embodiments of the present invention; Figure 4 This is a front view of the centering device according to one or more embodiments of the present invention; Figure 5 This is a cross-sectional view of the centering device according to one or more embodiments of the present invention; Figure 6 This is a schematic diagram of the fixed head structure according to one or more embodiments of the present invention.

[0020] Among them, 1. Anchor, 1-1. Pre-tightening coupling nut, 1-2. Connecting tray, 1-3. End tray; 2. GFRP reinforcement, 3. Concrete surface layer, 4. Reinforcing mesh, 5. Cement grout, 6. Centering device, 6-1. Fixing ring, 6-2. Connecting rod, 6-3. Bolt, 6-4. Fixing head. Detailed Implementation

[0021] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0022] For ease of description, the words "up," "down," "left," and "right" appearing in this invention only indicate that they are consistent with the up, down, left, and right directions of the accompanying drawings themselves. They do not limit the structure and are merely for the purpose of facilitating the description of this invention and simplifying the description. They do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] Example 1: This embodiment provides a soil nailing wall support system, such as Figure 1 and Figure 2 As shown, it includes a steel mesh 4, a concrete surface layer 3, and several sets of anchoring structures. The anchoring structures include anchors 1 and GFRP bars 2. The multiple sets of anchoring structures work together to arrange the anchors 1 and GFRP bars 2 in multiple rows and columns.

[0024] Specifically, the anchor 1 includes a pre-tightening coupling nut 1-1 and a tray structure. The tray structure extends a certain length along the length of the concrete surface layer 3. Multiple pre-tightening coupling nuts 1-1 are evenly spaced along the length of the tray structure. GFRP bars 2 correspond one-to-one with the pre-tightening coupling nuts 1-1. In this embodiment, the anchor 1 and GFRP bars 2 are made of the same material, namely GFRP, to increase the support durability.

[0025] The pallet structure is composed of multiple pallets joined together, such as Figure 3 As shown, the pallet structure includes a connecting pallet 1-2 and end pallets 1-3. The connecting pallet 1-2 has a Z-shaped structure, making the splicing surface between adjacent pallets a stepped surface. End pallets 1-3 are provided at both ends of the pallet structure. The end pallets 1-3 have a rectangular structure and can cooperate with the connecting pallet 1-2 to form a complete pallet structure. The pallet structure of this embodiment increases the contact area through the stepped splicing surface, which can improve the shear resistance and displacement resistance between adjacent pallets. At the same time, since the pre-tightening coupling nut 1-1 is connected to the pallet structure through steel bars, the stepped splicing surface provides a more stable base for the nut, ensuring that the pre-tightening force is evenly transmitted to the entire pallet structure.

[0026] Furthermore, the connecting tray 1-2 includes a central main body portion and protruding portions connected to both ends of the main body portion, according to... Figure 3As shown, the protruding portion at one end of the main body is located on the lower side, and the protruding portion at the other end is located on the upper side, thus forming a Z-shaped structure for the entire connecting tray 1-2. In this embodiment, the thickness of the protruding portion is half the thickness of the main body, so as to leave a mating surface for connecting the other connecting trays 1-2 or end trays 1-3; and the length of the protruding portion is equal to the length of the main body, and the length of the end trays 1-3 is equal to the length of the protruding portion.

[0027] In this embodiment, the adjacent connecting trays 1-2, the mating surfaces of connecting trays 1-2 and end trays 1-3, and the main body of connecting trays 1-2 are provided with the same number of mounting holes, for example, two mounting holes are provided for each, and the pre-tightening coupling nut 1-1 is installed through the mounting holes.

[0028] like Figure 3 As shown, the pre-tensioning coupling nut 1-1 has a threaded hole extending through it along the axial direction. The threaded hole is compatible with the external thread of the GFRP reinforcement 2 to ensure that the anchor 1 and the GFRP reinforcement 2 will not slip relative to each other after installation. The pre-tensioning coupling nut 1-1 includes a cylindrical section and a tapered section connected as one piece. The tapered section mates with the mounting hole of the tray structure to achieve a stable fit between the pre-tensioning coupling nut 1-1 and the tray structure.

[0029] During installation, the GFRP reinforcement 2 is first passed through the tray structure, and the tray structure is then fitted to the outer surface of the steel mesh 4. Afterwards, it is locked using the pre-tightening coupling nut 1-1, with the tapered section of the pre-tightening coupling nut 1-1 positioned within the mounting hole of the tray structure. After the anchor 1 is installed, the connecting tray 1-2 and the end tray 1-3 are fixed to the GFRP reinforcement 2 and the steel mesh 4 using the pre-tightening coupling nut 1-1. The interaction between the GFRP reinforcement 2 and the steel mesh 4 provides anchoring force to the support structure.

[0030] The length and diameter of the GFRP reinforcement 2 are determined according to the design requirements of the soil nail pull-out bearing capacity. Typically, the length of the GFRP reinforcement 2 is 5~11m and the diameter is 18~22mm. After the GFRP reinforcement 2 is placed in the soil, it forms an integral whole with the concrete surface layer 3 and the steel mesh 4 through the anchor 1, making the soil a composite body with better integrity and greater stiffness to restrain soil deformation.

[0031] like Figure 1 As shown, centering devices 6 are installed at certain intervals along the length of the GFRP reinforcement 2, serving as positioners for the GFRP reinforcement 2. Figure 4 and Figure 5As shown, the centering device 6 includes a fixing ring 6-1, a fixing head 6-4, and a connecting rod 6-2. The fixing ring 6-1 is a circular ring structure, and the diameter of the fixing ring 6-1 is slightly smaller than the diameter of the anchor hole to ensure that the GFRP reinforcement 2 can be smoothly placed into the anchor hole after the centering device 6 is installed. Two fixing heads 6-4 are symmetrically arranged inside the fixing ring 6-1, and the GFRP reinforcement 2 is clamped and fixed by the two fixing heads 6-4.

[0032] The fixing head 6-4 is connected to the inner wall of the fixing ring 6-1 via the connecting rod 6-2. The inner side of the fixing head 6-4 has an arc-shaped groove, the curvature of which matches the GFRP reinforcement 2. Extending portions are provided on both sides of the fixing head 6-4, and these opposing extending portions are connected by bolts 6-3. Figure 6 As shown, the inner wall of the arc-shaped groove has threads that are compatible with the GFRP rib 2.

[0033] In this embodiment, the centering device 6 is installed every 2m along the length of the GFRP bar 2. Since the diameter of the fixing ring 6-1 is not much different from that of the anchor hole, the GFRP bar 2 can be placed in the anchor hole in a concentric state with the anchor hole by the cooperation of multiple centering devices 6, thereby ensuring that the subsequent cement grout 5 uniformly wraps the GFRP bar 2.

[0034] like Figure 1 As shown, the concrete surface layer 3 is sprayed onto the outside of the anchor 1, the steel mesh 4, and the GFRP reinforcement 2, forming a whole with the steel mesh 4 and the GFRP reinforcement 2. This effectively fixes the GFRP reinforcement 2 and the anchor 1 and restricts the deformation of the surface soil. The thickness of the concrete surface layer 3 meets the requirement of completely covering the anchor 1, typically 80~100mm.

[0035] The specific parameters of the reinforcing mesh 4 are designed according to the project overview. The reinforcing mesh 4 and the GFRP bars 2 together form the skeleton of the concrete surface layer 3 to improve the load-bearing capacity of the concrete surface layer 3. In this embodiment, the diameter of the reinforcing bars in the reinforcing mesh 4 is 6~10mm, the mesh width is 100~250mm, and the lap length of the reinforcing mesh 4 is greater than 300mm.

[0036] In this embodiment, the tray structure is segmented and spliced, with a stepped contact surface. The anchor 1 and the tray structure are fixed to the steel mesh 4 via GFRP bars 2, allowing the anchor 1 and the steel mesh 4 to interact, effectively increasing the contact area with the concrete surface layer 3 and thus improving the anchoring force. The GFRP bars 2 can also act as reinforcing bars inside the concrete surface layer 3, improving its strength. Furthermore, the GFRP bars 2 are equipped with multiple centering devices 6, ensuring the installation accuracy of the GFRP bars 2 within the anchor holes and effectively guaranteeing the support effect.

[0037] In this embodiment, the anchor 1 is also made of GFRP material, and GFRP reinforcement 2 is also provided. GFRP reinforcement 2 has low shear strength, which makes it easy to remove and reduces the difficulty of subsequent obstacle removal.

[0038] Example 2: This embodiment provides a construction method for a soil nailing wall support system, using the support system described in Embodiment 1, including the following steps: Step 1: Slope excavation and restoration.

[0039] Earthwork excavation was carried out according to the designed excavation depth of the foundation pit. In this embodiment, the slope was excavated in a single stage with a slope toe of 75° and an excavation depth of 5m. After the slope excavation was completed, a backhoe excavator was used to clear the slope. When about 30cm of the slope thickness remained to be cleared, manual clearing was used to strictly control the slope ratio.

[0040] Step 2: Positioning and laying out the lines.

[0041] Based on the design drawings, the axis of the foundation pit or the top / bottom edge line of the slope are measured. The starting edge line of the soil nailing wall is laid out using a total station. Wooden piles or steel bars are driven into the top or bottom of the slope, and longitudinal or transverse control lines are set up. After the control lines are set up, a total station with a steel tape is used to cross-lay out on the slope to determine the center point of each anchor hole, and the hole positions are numbered using spray paint.

[0042] Step 3: Hole forming and cleaning.

[0043] Reinforcing bars are inserted next to the hole location, and the design inclination angle is marked with an angle gauge to guide the drilling rig in alignment. After the drilling rig is aligned and in place, the hole location and angle are re-measured to ensure that the hole opening deviation is less than 50 mm. In this embodiment, the inclination angle is 15° and the hole diameter is 150 mm.

[0044] After the hole is formed, use the drilling rig to repeatedly lift the drill 2-3 times to clean the residue inside the anchor hole.

[0045] Step 4: Install the centering device 6.

[0046] The centering device 6 is fixed at a predetermined position on the GFRP rib 2. In this embodiment, the centering device 6 is fixed at a distance of 2 m from the end of the GFRP rib 2, and a centering device 6 is set every m.

[0047] First, insert the centering device 6 into the predetermined position, then tighten the bolt 6-3, and make the internal thread of the fixing head 6-4 match the thread of the GFRP rib 2 to ensure that the centering device 6 and the GFRP rib 2 will not be displaced relative to each other.

[0048] Step 5: Install GFRP reinforcement 2.

[0049] Place the GFRP bar 2 into the pre-drilled anchor hole. After the GFRP bar 2 is placed to the designed depth, leave an exposed section of about 1m for the installation of the anchor 1.

[0050] Step 6: Grouting.

[0051] The cement grout 5 is injected into the bottom of the hole using a grouting pump. During grouting, the grouting pipe should be tied to the rod of the GFRP reinforcement 2 first. At the same time, the grouting pipe is inserted into the hole and grouting is started from the bottom of the hole. The distance from the end of the grouting pipe to the bottom of the hole should not be greater than 200mm. The grouting pressure is 0.5 MPa.

[0052] Stop grouting once the grout flows out of the borehole, and slowly pull out the grouting pipe. During grouting and pipe pulling, always ensure the grouting pipe opening is submerged in the grout surface to guarantee the borehole is full of grout. After grouting, replenish the grout promptly when the grout level drops. The grouting sequence should proceed row by row from the toe of the slope to the top to avoid grout loss.

[0053] In this embodiment, the cement slurry 5 is a cement slurry with a water-cement ratio of 0.5.

[0054] Step 7: Tie the reinforcing mesh 4.

[0055] First, tie the reinforcing mesh 4. The reinforcing mesh 4 is tied in sections, each section being 1 m long. The upper end of the first section of the reinforcing mesh 4 is fixed to the top of the slope. Then, the remaining part of the first section of the reinforcing mesh 4 is laid on the prepared slope surface. Then, the next section of the reinforcing mesh 4 is overlapped and tied, with an overlap length of 350 mm. Step 8: First sprayed concrete surface layer 3.

[0056] Concrete spraying should be carried out 2-6 hours after grouting is completed. A wet spraying machine should be used for spraying concrete. The spraying operation should be carried out in sections and in sequence. Each section should be sprayed evenly from bottom to top. The thickness of the first spray should be 30 mm.

[0057] When spraying concrete, the nozzle should be kept perpendicular to the surface of the soil nailing wall, and the distance between them should be 0.6~1.0 m. In this embodiment, the concrete surface layer 3 uses C20 concrete. Step 9: Install anchor 1.

[0058] Six hours after the first spraying of concrete surface layer 3, anchorage 1 is installed. First, the end tray 1-3 is inserted through the exposed section of GFRP reinforcement 2 and installed at the rightmost end of this section of soil nailing wall. Then, the connecting tray 1-2 is inserted sequentially from right to left through the exposed section and installed onto the surface of the reinforcing mesh 4. Next, the end tray 1-3 is placed on the leftmost end of the connecting tray 1-3 to form a whole. Finally, the pre-tightening coupling nut 1-1 is screwed in to fix the end tray 1-3, connecting tray 1-2, and reinforcing mesh 4, providing anchoring force for the entire support system.

[0059] Step 10, Second sprayed concrete surface layer 3.

[0060] After anchor 1 is installed, a second shotcrete application is performed, following the same sequence and method as the first application. The shotcrete thickness is 30-80 mm, and the final shotcrete layer 3 should completely cover anchor 1. Water spraying support should be applied promptly 2 hours after the shotcrete has set.

[0061] In this embodiment, the concrete surface layer 3 is sprayed in two stages. The first spraying of the concrete surface layer 3 can quickly seal the soil surface to prevent rainwater erosion or soil spalling, while providing initial protection for the steel mesh 4. At this time, the anchor 1 has not yet been installed, avoiding interference from the installation of the anchor 1 by the sprayed concrete. After the anchor 1 is installed, the second spraying is carried out to completely cover the anchor 1 and the steel mesh 4, forming a continuous concrete surface layer 3 and ensuring the construction effect.

[0062] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A soil nailing wall support system, characterized in that, It includes a steel mesh, a concrete surface layer, and multiple sets of anchoring structures. The anchoring structures include anchors and GFRP bars. The anchors are installed at one end of the GFRP bars. Multiple centering devices are arranged at intervals along the length of the GFRP bars. The centering devices are used to match the anchor holes. The anchor includes a tray structure and a pre-tightening coupling nut, with the pre-tightening coupling nut installed on one side of the tray structure and the other side of the tray structure used to attach the reinforcing mesh; the concrete surface layer covers the reinforcing mesh and the anchor.

2. The soil nailing wall support system according to claim 1, characterized in that, Multiple mounting holes are evenly spaced along the length of the tray structure, and a pre-tightening coupling nut is installed in each mounting hole.

3. A soil nailing wall support system according to claim 1 or 2, characterized in that, The pallet structure includes a connecting pallet and end pallets, the contact surface between adjacent connecting pallets is a stepped surface, and the end pallets are located at both ends of the connecting pallets.

4. The soil nailing wall support system according to claim 2, characterized in that, The pre-tightening coupling nut has a cylindrical section and a tapered section connected as one piece, and the mounting hole is a tapered hole adapted to the tapered section.

5. A soil nailing wall support system according to claim 1, characterized in that, The centering device includes a fixing ring and a fixing head installed inside the fixing ring. The two fixing heads are arranged opposite each other to clamp the GFRP reinforcement.

6. A soil nailing wall support system according to claim 5, characterized in that, One side of the fixing head is connected to the inner wall of the fixing ring via a connecting rod, and the other side has an arc-shaped groove with threads on the surface of the arc-shaped groove that are compatible with GFRP ribs.

7. A soil nailing wall support system according to claim 1, characterized in that, The anchor is made of GFRP material.

8. A construction method for a soil nailing wall support system according to any one of claims 1-7, characterized in that, include: Multiple centering devices are fixed to the GFRP reinforcement at a set distance; Then, the GFRP reinforcement is placed into the anchor hole; Cement grout is injected into the bottom of the hole using a grouting pump; after grouting is completed, steel mesh is tied and the first concrete surface layer is sprayed. Then, the anchors are installed on the sections of the GFRP reinforcement bars that are exposed in the anchor holes. After all the anchors are installed, the second shotcrete layer is applied.

9. A construction method for a soil nailing wall support system according to claim 8, characterized in that, During grouting, first fix the grouting pipe to the GFRP reinforcement rod; then insert the grouting pipe into the hole and start grouting from the bottom of the hole.

10. A construction method for a soil nailing wall support system according to claim 8, characterized in that, After the first shotcrete surface layer is sprayed for a set time, the anchors are installed. The end plate is placed at one end, and each connecting plate is installed in sequence, and finally the other end plate is installed; then the pre-tightening coupling nut is screwed in.

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