A modular centering and staged grouting soil nailing wall support structure

Abstract

This utility model provides a modular soil nailing wall support structure with centering and staged grouting, including prestressed steel bars, grouting pipes, centering locators, grouting sleeves, concrete, steel plates, nut assemblies, and soil. The prestressed steel bars are installed in the grouting sleeves via spaced-apart centering locators. Both the prestressed steel bars and the centering locators are modular standard parts connected by plug-in joints. The grouting pipes surround the prestressed steel bars and are arranged parallel to them, also designed as precast components. The concrete is placed at the outer end of the grouting sleeve of the soil body to form a reinforcement layer to suppress soil deformation. The steel plate is placed at the outer end of the concrete and is a precast component. The nut assembly is threaded to the outer end of the prestressed steel bars and pressed against the outer end of the steel plate, also serving as a precast component. This support structure has the advantages of modularity, easy centering and positioning, and support for staged grouting.

Description

Technical Field

[0001] This utility model relates to the field of rock engineering technology, specifically to a modular centering and staged grouting soil nailing wall support structure. Background Technology

[0002] Soil nailing wall support structures are composite reinforcement structures formed by densely packed soil nails in the in-situ soil of the foundation pit sidewall, combined with a surface protective layer. Soil nails, as the core load-bearing units, are typically slender rod-shaped members. During construction, reinforcing bars are inserted through drilling or steel pipes and angle steel are directly driven in, and a grouting process is used to form a wrapping layer to enhance their synergistic effect with the soil. This structure mainly relies on the interfacial bonding and frictional effect between the soil nails and the surrounding soil to transfer loads, exerting its reinforcement effectiveness through a passive tensile mechanism during soil deformation. The densely distributed soil nails and the in-situ soil form a composite structure, significantly improving the overall shear strength and stability of the soil, with mechanical properties similar to gravity retaining walls. A complete soil nailing wall system consists of the following key components: soil nail group, in-situ soil, shotcrete surface layer, and drainage facilities. The interaction between the soil nails and the soil ensures the synergistic bearing capacity within the composite structure, while the composite structure as a whole maintains the external balance of the support system by resisting external active earth pressure.

[0003] Technical drawbacks of traditional soil nailing wall support structures: 1. Lack of modularity: Components such as anchor bolts, grouting pipes, and reinforcing mesh in traditional soil nailing walls require on-site processing and installation, which is cumbersome and reliant on manual labor. For example, anchor bolts require on-site drilling, insertion of reinforcing bars, and grouting, which is time-consuming and labor-intensive, making rapid assembly impossible. Parameters such as anchor bolt length and grouting pipe specifications lack unified design standards and are difficult to adapt to varying geological conditions.

[0004] 2. Inability to achieve centering: Anchor bolt installation relies on worker experience for adjustment, which can easily lead to deviation from the borehole axis (eccentricity error can reach 5~10mm), resulting in uneven grouting and weak local bonding. Risk: Eccentric anchor bolts are prone to bending moments under stress, causing stress concentration, especially in soft soil layers, increasing the probability of anchor bolt breakage.

[0005] 3. Uneven grout distribution: Traditional grouting is mostly a one-time high-pressure injection, and the grout tends to spread preferentially along cracks or loose areas, resulting in the anchoring section not being filled densely (the void rate can reach 15%). Utility Model Content

[0006] The purpose of this utility model is to address the shortcomings of existing technologies by providing a modular soil nailing wall support structure that is easy to center and position, and supports staged grouting.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is: a modular centering and phased grouting soil nailing wall support structure, including prestressed steel bars, grouting pipes, centering positioners, grouting sleeves, concrete, steel plates, nut assemblies, and soil. The grouting sleeve is pre-embedded in the borehole of the soil to provide a channel for grouting; The prestressed steel bars are installed in the grouting sleeve through spaced centering positioners. The centering positioners are fitted around the prestressed steel bars to ensure the centering of the prestressed steel bars relative to the grouting sleeve. Both the prestressed steel bars and the centering positioners are modular standard parts and are connected by plug-in connection. Multiple grouting pipes are provided and arranged around the prestressed steel bars and parallel to the prestressed steel bars for grouting; The concrete is placed at the grouting sleeve at the outer end of the soil body to form a reinforcement layer to inhibit soil deformation; The steel plate is set at the outer end of the concrete and serves as the bearing plate at the end of the soil nail; it is a prefabricated standard component. The nut assembly is threaded to the outer end of the prestressed steel bar and pressed against the outer end of the steel plate to transmit tension force. It is a prefabricated standard component.

[0008] Preferably, two layers of metal mesh are embedded in the concrete, and the horizontal and vertical spacing of the metal mesh are equal.

[0009] Preferably, the metal mesh is a Q-246 type metal mesh with a horizontal spacing of 10cm and a diameter of 5.6mm, a vertical spacing of 10cm and a diameter of 5.6mm, and is woven from metal wires with a diameter of 5.6mm to form a mesh skeleton.

[0010] Preferably, the steel plate has a double-layer steel plate structure, with the bottom steel plate directly connected to the concrete and the top steel plate having an epoxy resin coating on its surface.

[0011] Preferably, the nut assembly includes a nut, a washer, and a wedge. The nut is threaded to the tail end of the prestressed steel bar, and the nut is pressed against the surface of the steel plate by the washer and the wedge.

[0012] Preferably, the steel plate has dimensions of 200×200×15mm.

[0013] Preferably, there are at least three grouting pipes, which are evenly distributed around the prestressed steel bars.

[0014] Preferably, the diameter of the grouting pipe is 12.7 mm.

[0015] Preferably, the grouting pipe path is positioned to abut against the centering locator in the area of ​​the centering locator.

[0016] Preferably, the grouting pipe is a prefabricated standard component.

[0017] This utility model has substantial features and progress compared to the prior art. Specifically, this utility model has the following advantages: 1. Achieve modular design and efficient construction By prefabricating anchor bolts, centering devices, steel plates, nuts, and grouting pipes, an integrated modular structure is formed, transforming the discrete construction process into standardized assembly operations. This solves the problems of cumbersome component processing and serious material waste in traditional processes. The design features quick-connect anchor bolt-centering device units, a modular grouting system, and detachable panels, realizing an industrialized construction mode of "factory prefabrication and on-site assembly," shortening the construction period by more than 30%.

[0018] 2. Ensure precise alignment and uniform force distribution of the anchor bolts. A centering locator is introduced to force centering, ensuring that the deviation between the anchor bolt axis and the borehole center is ≤2mm, and the symmetry of the grouting body coverage reaches over 95%. This eliminates manual positioning errors, avoids uneven grouting and stress concentration problems caused by anchor bolt eccentricity, and improves the overall stability of the support structure.

[0019] 3. Optimize the phased grouting process and its adaptability to the formation. A multi-stage grouting control system was developed to dynamically adjust the grouting pressure and stage intervals based on the formation permeability, ensuring that the grout uniformly fills the fractures and increasing the compactness of the anchoring section to over 90%. This solves the problems of grout runaway, high void ratio, and poor formation adaptability of traditional single-stage grouting, enabling precise anchoring in complex formations. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a modular centering and phased grouting soil nailing wall support structure according to this utility model.

[0021] Figure 2 This is an axial cross-sectional view of the grouting sleeve of a modular centering and staged grouting soil nailing wall support structure according to this utility model.

[0022] Figure 3 This is a detailed drawing of the centering positioner in this utility model.

[0023] In the diagram: 1. Metal mesh; 2. Steel plate; 3. Outer thread of prestressed steel bar; 4. Nut assembly; 5. Lower steel plate; 6. Concrete; 7. Centering locator; 8. Grouting sleeve; 9. Prestressed steel bar; 10. Grouting pipe. Detailed Implementation

[0024] The technical solution of this utility model will be further described in detail below through specific embodiments.

[0025] like Figures 1-3 As shown, a modular soil nailing wall support structure with centering and staged grouting includes prestressed steel bars 9, grouting pipes 10, centering positioners 7, grouting sleeves 8, concrete 6, steel plates 2, nut assemblies 4, and soil.

[0026] The grouting sleeve 8 is pre-embedded in the borehole of the soil to provide a channel for staged grouting and ensure that the grout penetrates into the rock and soil fissures.

[0027] The prestressed steel bar 9 is installed in the grouting sleeve 8 through spaced centering positioners 7. The centering positioners 7 are fitted outside the prestressed steel bar 9 to ensure the centering of the prestressed steel bar 9 relative to the grouting sleeve 8. Both the prestressed steel bar 9 and the centering positioners 7 are modular standard parts and are connected by plug-in connection.

[0028] The prestressed steel bar 9 has a specification of 22mm and serves as the main body of the soil nail. It bears tensile stress through high-strength threaded steel bars and anchors deep soil. It works in conjunction with the centering positioner and grouting pipe to form a composite anchor body of "steel bar-cement grout-soil".

[0029] Multiple grouting pipes 10 are provided and arranged around the prestressed steel bars 9 and parallel to the prestressed steel bars 9 for grouting. In this embodiment, there are three grouting pipes 10 with a diameter of 12.7 mm and an adjacent spacing angle of 90°. Through a multi-stage grouting process, the bonding strength between the anchor body and the rock and soil is improved.

[0030] The grouting pipe is positioned to abut against the centering locator in the area of ​​the centering locator, and the grouting pipe is a prefabricated standard component.

[0031] The concrete 6 is placed at the grouting sleeve 8 at the outer end of the soil body to form a reinforcement layer to suppress soil deformation; the excavation face is covered by high-pressure jetting and combined with Q-246 type metal mesh to form a flexible reinforcement layer to suppress soil deformation.

[0032] The metal mesh 1 has a horizontal spacing of 10cm and a diameter of 5.6mm, and a vertical spacing of 10cm and a diameter of 5.6mm. It is woven from metal wires with a diameter of 5.6mm. The horizontal and vertical spacings are both 10cm, forming a mesh skeleton to enhance the tensile strength of the shotcrete layer and prevent local spalling or cracking of the soil. Combined with the shotcrete, it forms a composite reinforcement layer that evenly transmits soil pressure to the soil nail anchoring system.

[0033] The steel plate 2 is set at the outer end of the concrete 6 as the bearing plate of the soil nail end and is a prefabricated standard part. In this embodiment, the steel plate 2 has a double-layer structure. The lower steel plate 5 serves as the bearing pad of the soil nail end, with a specification of 200×200×15mm, which increases the contact area and avoids local stress concentration. The upper steel plate is protected against corrosion by epoxy resin coating, which extends its service life. Together with bolts, nuts, washers and wedges, it forms the anchoring end, which disperses the soil nail tension to the support surface layer.

[0034] The nut assembly 4 is connected to the outer end thread 3 of the prestressed steel bar and pressed against the outer end of the steel plate 2 to transmit tension. It is a prefabricated standard part. In this embodiment, it includes a nut, a washer and a wedge. The nut is threaded to the tail end of the prestressed steel bar and is pressed against the surface of the steel plate by the washer and the wedge.

[0035] The specific construction process is as follows: Anchor drilling After the surveying team completes the anchor bolt positioning and layout, equipment is deployed and drilling begins, following the hole diameter and anchor bolt length specified in the design drawings. If necessary, shotcrete can be applied to the drilling area to protect the integrity of the soil structure. All anchor bolts are installed at a 15° inclination angle.

[0036] The drilling method used must ensure that the borehole remains stable until grouting is completed.

[0037] Anchor bolt assembly and installation Anchor bolts must be pre-assembled before drilling, including cutting and bending the reinforcing bars, installing the locator, grouting pipe, grouting valve, and binding the anchoring section. After drilling is completed and the borehole is cleaned with compressed air, the anchor bolts are installed, and grouting is permitted.

[0038] The anchor structure needs to be inspected annually by a geotechnical engineer, who will randomly check the anchor structure and permanent anchor heads for any abnormalities, including but not limited to the condition of the anti-corrosion treatment, the integrity of the anchor head, and any possible cracks, leaks, displacements, or other defects.

[0039] Cement grouting The grouting of cement grout should proceed from the bottom of the anchor hole toward the opening, and can be carried out in stages or sections to achieve complete filling of the hole. If the water-cement ratio is not specified in the design, the mix proportion of cement grout should be a water-cement ratio (a / c) of 0.5 to 0.7 (by weight).

[0040] The slurry should be prepared using a high-turbulence mixer with a mixing volume equivalent to 1 to 2 bags of cement.

[0041] The injection of cement grout must conform to the parameters specified in the design specifications. Grouting should first be carried out by ascending method (from the bottom of the hole to the opening) to complete the construction of the sheath. At this stage, the water-cement ratio must be ≤0.5. Subsequent grouting stages can be carried out in sections or zones to fill the entire cavity. The water-cement ratio should be ≤0.7.

[0042] After the sheath construction is completed, wait 12 to 24 hours before grouting the anchoring section through the grouting pipe. The injected cement grout should have sufficient pressure to break through the sheath, but the pressure should not exceed 5.0 kgf / cm². Specifically, in this embodiment, the grouting stage involves three stages: Stage 1: initial grouting to fill the borehole voids; Stage 2: pressurized grouting to compact the anchoring section; Stage 3: local reinforcement for complex strata. This multi-stage grouting process enhances the bond strength between the anchor body and the soil / rock mass.

[0043] Installation of metal mesh Welded steel mesh should be installed according to the horizontal and vertical overlap lengths specified in the design. If necessary, reinforcing steel mesh and / or anchoring steel bars should be installed in the anchor area.

[0044] Shotcrete lining Anchor bolt elevation and layout line All construction activities listed above shall be carried out in accordance with the standardized construction sequence and methods specified in the design, and shall be advanced to the final design elevation of the slope.

[0045] Finally, it should be noted that: the preferred embodiments of this patent have been described in detail above, but this patent is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this patent.

Claims

1. A modularly centred and staged grouted soil nailing wall support structure, characterised in that: This includes prestressed steel bars, grouting pipes, centering positioners, grouting sleeves, concrete, steel plates, nut assemblies, and soil. The grouting sleeve is pre-embedded in the borehole of the soil to provide a channel for grouting; The prestressed steel bars are installed in the grouting sleeve through spaced centering positioners. The centering positioners are fitted around the prestressed steel bars to ensure the centering of the prestressed steel bars relative to the grouting sleeve. Both the prestressed steel bars and the centering positioners are modular standard parts and are connected by plug-in connection. Multiple grouting pipes are provided and arranged around the prestressed steel bars and parallel to the prestressed steel bars for grouting; The concrete is placed at the grouting sleeve at the outer end of the soil body to form a reinforcement layer to inhibit soil deformation; The steel plate is set at the outer end of the concrete and serves as the bearing plate at the end of the soil nail; it is a prefabricated standard component. The nut assembly is threaded to the outer end of the prestressed steel bar and pressed against the outer end of the steel plate to transmit tension force. It is a prefabricated standard component.

2. The modularly centered, positioned and staged grouted soil nailed wall retaining structure according to claim 1, characterized in that: Two layers of metal mesh are embedded in the concrete, with equal horizontal and vertical spacing between the metal meshes.

3. The modularly centered, positioned and staged grouted soil nailed wall retaining structure according to claim 2, wherein: The metal mesh is a Q-246 type metal mesh with a horizontal spacing of 10cm and a diameter of 5.6mm, a vertical spacing of 10cm and a diameter of 5.6mm, and is woven from metal wires with a diameter of 5.6mm to form a mesh skeleton.

4. The modularly centered, positioned and staged grouted soil nailed wall retaining structure according to claim 1 or 2, characterized in that: The steel plate has a double-layer structure, with the bottom steel plate directly connected to the concrete and the top steel plate having an epoxy resin coating on its surface.

5. The modularly centered, positioned and staged grouted soil nailed wall retaining structure as claimed in claim 1, wherein: The nut assembly includes a nut, a washer, and a wedge. The nut is threaded to the tail end of the prestressed steel bar, and the nut is pressed against the surface of the steel plate by the washer and the wedge.

6. The modularly centered, positioned and staged grouted soil nailed wall retaining structure as claimed in claim 1, wherein: The steel plate has dimensions of 200×200×15mm.

7. The modularly centered, positioned and staged grouted soil nailed wall retaining structure as claimed in claim 1, wherein: There are at least three grouting pipes, which are evenly distributed around the prestressed steel bars.

8. The modularly centered, positioned and staged grouted soil nailed wall retaining structure as claimed in claim 1, wherein: The diameter of the grouting pipe is 12.7 mm.

9. The modularly centered, positioned and staged grouted soil nailed wall retaining structure as claimed in claim 1, wherein: The grouting pipe passes through the area of ​​the centering locator and is set to abut against the centering locator.

10. The modularly centered, positioned and staged grouted soil nailed wall retaining structure as claimed in claim 1, wherein: The grouting pipe is a prefabricated standard component.

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