Enclosed structure between multi-dimensional protective support piles and construction method

Abstract

The invention discloses a sealing structure between multi-dimensional protection supporting piles and a construction method. The sealing structure comprises the supporting piles, a top beam, a sealing net, a supporting grid frame rib set, an anchor rod assembly, a water drainage pipe and a concrete layer. The closed net is arranged on the free side of rock soil, the supporting grid frame rib sets are fixed to the outer side of the closed net, the spiral ring ribs form a square frame to press and fix the closed net to the supporting piles and the top beam, and the multiple sets of ribs are arranged in a grid shape and serve as stiffening ribs to make the unfolding face of the closed net straight. The anchor rod assembly penetrates through a rib screw ring and is anchored into rock soil, grouting and crack filling are conducted, and the water drainage pipe pertinently drains seepage water; the concrete layer wraps and integrates all the components to form the composite protection system. The closed structure solves the problems of frequent rockfall, hollowing and falling, unsmooth seepage and drainage and complex construction of a net spraying structure between traditional support piles, further has the advantages of being convenient to install, free of high-altitude welding and adaptive to fractured rock geology such as moderately strong weathered rocks, greatly improves the stability of the closed structure and rock soil between the piles, and improves the construction efficiency. And the construction safety risk and the full life cycle cost are reduced.

Description

Technical Field

[0001] This invention belongs to the field of foundation pit support technology, and more specifically, relates to a multi-dimensional protective support pile-sealing structure and construction method. Background Technology

[0002] Currently, large underground sewage treatment plants and waterworks, lacking superstructure ballast, tend to be located in geological environments with sandstone, moderately weathered rock, and limited fissure water. These environments are less affected by geological and hydrological conditions and better suit the engineering construction needs. Based on these geological characteristics, the industry commonly uses a "cast-in-place pile + inter-pile shotcrete" structure as the core support structure. This structure provides the main support through cast-in-place piles, which, combined with inter-pile shotcrete, form overall protection, making it the mainstream solution for foundation pit support in such projects.

[0003] However, the shotcrete section of the traditional "cast-in-place pile + inter-pile mesh spraying" structure has significant technical defects. The steel mesh used has large holes, which cannot effectively restrain the fractured rock in the geology before shotcreting. This results in the fractured rock being exposed to the external environment for a long time, making it prone to rockfalls due to sun and rain, posing a significant safety hazard to construction. Simultaneously, the steel mesh itself is prone to corrosion, and the on-site implementation process is complex and the fixing is weak. During shotcreting, it is difficult to achieve dense filling on the back of the steel mesh. Later, due to steel corrosion, hollowing of the shotcrete protective layer, and water erosion, the fractured rock is prone to detachment, leading to problems such as rust leakage and detachment of the protective layer, seriously affecting the stability and service life of the support structure.

[0004] Given the numerous problems encountered by traditional support structures in geological environments rich in fractured rocks, the industry urgently needs targeted technological improvements. Currently, providing suitable inter-pillar sealing structures for fractured rocks such as moderately weathered rocks and sandstone has become a key requirement in engineering construction. This requires effectively avoiding the safety risks of rock strata falling and injuring people during construction, while also addressing core technical pain points such as insufficient stability between the sealing structure and the soil and rock between piles, hollowing and falling off of the sealing structure, poor drainage between structural layers, and complex construction of the sealing structure. This will improve the safety, stability, and ease of construction of foundation pit support, and meet the demand for high-quality support in engineering construction. Summary of the Invention

[0005] In view of the problems that existing technologies for foundation pit support piles are prone to steel corrosion, hollowing of the sprayed protective layer, and easy detachment of fractured rock, this invention provides a multi-dimensional protective support pile-sealing structure and construction method to solve these problems.

[0006] To achieve the above objectives, the present invention provides a multi-dimensional protective support pile-interlocking structure, comprising: a sealing mesh located on the free side of the soil and rock between the support piles, with a mesh size of 1-5cm. The structure consists of steel plate mesh or wire mesh; a support grid reinforcement group fixedly connected to the outside of the closed net, including spiral ring reinforcement and rib reinforcement; four sets of spiral ring reinforcement are connected end to end to form a square frame, and steel nails are used to pass through the first spiral ring on the spiral ring reinforcement, thereby pulling the edge of the closed net and pressing it onto the support piles and the cap beam respectively; multiple sets of rib reinforcement are provided and vertically intersecting to form a grid structure, with both ends fixedly connected to the corresponding spiral ring reinforcement, and multiple sets of second spiral rings are provided on them at intervals; an anchor rod assembly with one end passing through the second spiral ring and inserted into the anchor hole, and multiple sets of arrayed anchor rod assemblies are grouted to form an anchoring part that is integrated with the soil and rock between the piles and seals the gaps between the soil and rock; a drainage pipe is inclined downwards and placed at the fracture zone and seepage point of the soil and rock between the piles; and a concrete layer, which is formed by spraying concrete onto the free side of the soil and rock between the support piles to wrap and integrate the closed net and the support grid reinforcement group.

[0007] Furthermore, the first and second spiral rings are aligned with the corresponding mesh openings of the closed mesh. Steel wire is used to bind and fix the first spiral ring to the mesh opening of the closed mesh, so that the spiral ring ribs are tightly attached to the closed mesh. Steel wire is used to bind and fix the second spiral ring on the rib to the corresponding mesh opening of the closed mesh, so that the ribs are completely attached to the closed mesh.

[0008] Furthermore, the two ends of the rib are provided with barbs with the outer diameter of the spiral ring rib as the inner diameter. By hooking the barbs at both ends of the rib to the corresponding spiral ring rib and binding them with steel wire, the fixed connection between the rib and the spiral ring rib is completed.

[0009] Furthermore, one end of the steel nail has a round cap with a diameter larger than the inner diameter of the first circular helical ring. The nail shank has ribs. The steel nail is driven through the first circular helical ring in sequence and into the support pile and the capping beam. The round cap of the steel nail is used to limit and compress the first circular helical ring, so that the two sides of the closed net are respectively stretched and compressed onto the adjacent support piles, the top edge is stretched and compressed onto the capping beam, and the bottom edge is limited by driving the steel nail into the bottom of the rock and soil between the piles, so that the surface of the closed net is straight.

[0010] Furthermore, the anchor assembly is anchored in the soil between piles through the second helical ring, and includes barbs, grouting rods, fiberglass self-adhesive tape, and threaded caps.

[0011] Furthermore, one end of the grouting rod passes through the second helical ring and is anchored in the corresponding anchor hole on the soil between the piles. It is a hollow rod with a diameter smaller than that of the second helical ring, and multiple sets of grouting holes are opened on the rod body for grouting. The barbs are fixed on the outer wall of the grouting rod to achieve mechanical fixation with the inner wall of the anchor hole. The fiberglass self-adhesive tape is wrapped around the rear end of the grouting rod to seal the anchor hole. The threaded cap is threaded to the tail end of the grouting rod.

[0012] Furthermore, the outer diameter of the grouting flower rod is 0.6-1.2 mm smaller than that of the second spiral ring, and the wall thickness is 1.2 mm. It is inclined upward in the rock and soil between the piles, with an upward inclination angle of 8°-12°, and the length of the rock anchoring end is ≥25 cm.

[0013] Furthermore, the drainage pipe includes a protective cover, a fiber cotton layer, a pipe body, a filter cloth, and positioning steel bars; the pipe body is located inside drainage holes in the soil and rock between piles, and its pipe body has multiple sets of water inlets; the drainage holes are respectively located at the exposed fracture zone, rock stratum joints, and seepage points after earthwork excavation, and are obtained by drilling; the fiber cotton layer is filled inside the pipe body; the positioning steel bars are vertically inserted into the pipe body to limit and fix the fiber cotton layer, and multiple sets of positioning steel bars are provided at intervals along the pipe body, passing through the water inlets and inserted into the fiber cotton layer for limiting and fixing; the filter cloth is wrapped around the outside of the pipe body; the protective cover is located at the outlet of the pipe body.

[0014] Furthermore, the pipe body has a diameter of 20-50mm, an installation downward tilt angle of 10°-15°, and an insertion depth into the soil or rock of ≥12cm.

[0015] According to another aspect of the present invention, a construction method for a multi-dimensional protective support pile-sealing structure is also provided, comprising the following steps: S1: Plan the layout of the enclosed structural facade based on geological conditions; S2: Select a closed net of appropriate size according to the layout plan, and use supporting grid reinforcement to tie and fix it to the closed net; S3: Excavate the foundation pit soil and rock layer by layer, with a single excavation depth ≤ m; control the over-excavation or under-excavation of the soil and rock surface between piles to ≤ 2 cm, and the local over-excavation or under-excavation area to ≤ 0.1 m², to ensure the flatness of the surface. S4: Roll up and lower the pre-assembled closed netting and support grid reinforcement group. First, fix the top of the support grid reinforcement group to the cap beam. Release it gradually as the excavation depth increases. Drive the steel nails through the first spiral ring of the spiral reinforcement into the support piles on both sides. S5: Mark the drilling point according to the position of the second threaded ring on the rib and complete the anchor hole drilling operation; drive the anchor bolt assembly through the second threaded ring into the anchor hole, use barbs to fix it initially, and seal the anchor hole gap with fiberglass self-adhesive tape. S6: Drill drainage holes at rock and soil fracture zones and seepage points, and insert drainage pipes wrapped with filter cloth, containing a layer of fiber cotton and positioning steel bars into the drainage holes; seal the gap between the pipe and the hole wall with cement grout, and cover the outlet with a disposable protective cover to prevent clogging. S7: Spray concrete layer by layer, first spraying the connection between the cap beam and the support piles, then spraying the middle area; ensure that the threaded cap is not covered, forming a concrete layer that wraps the closed mesh and the supporting grid reinforcement group; S8: After the concrete layer has cured, open the threaded cap and connect the grouting pipe; inject concrete grout, control the pressure to 0.3-0.5MPa, and add grout 2-3 times to ensure a filling degree ≥80%; after grouting, use the threaded cap to seal the end of the grouting rod; remove the protective cover of the drain pipe.

[0016] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1. The closed structure of this invention forms a mesh-reinforcement composite skeleton by supporting the grid reinforcement group and the closed mesh. The spiral reinforcement forms a square frame to define the outline of the closed mesh, and the ribs are vertically intersected to form a grid-like stiffening structure, which solves the problems of uneven stress and easy deformation of the traditional steel mesh. With the help of multiple arrayed anchor bolt components, the anchoring part is formed by grouting and is integrated with the rock and soil. This not only achieves a firm connection between the closed mesh and the rock and soil, but also fills the rock and soil cracks. At the same time, it works with the support piles and the cap beam to form a complete stress system, effectively dispersing the lateral pressure of the rock and soil and avoiding structural damage caused by local stress concentration.

[0017] 2. The closed structure of the present invention, by providing anchor bolt assemblies, has both anchoring and grouting functions. The grout can penetrate into the cracks in the soil and rock and the voids between the closed mesh and the soil and rock, and after solidification, it forms a dense anchoring structure, eliminating the void problem caused by the non-dense filling of traditional sprayed mesh protective layers; at the same time, the concrete layer completely wraps and integrates the closed mesh and the supporting grid reinforcement, forming a closed mesh-reinforcement-concrete composite protection system. Combined with the pull-out resistance of the anchor bolt assemblies, it greatly reduces the risk of the closed structure falling off due to corrosion and water erosion in the later stage.

[0018] 3. The closed structure of this invention uses a steel wire mesh or steel plate mesh with a mesh size of 1-5cm, which is directly attached to the free side of the rock and soil between piles to form the first physical barrier. This effectively restrains the fractured rock and avoids the problem that traditional large-pore steel mesh cannot intercept falling rocks, greatly reducing the safety risk of rock detachment and injury during construction. Moreover, the over-excavation and under-excavation of the free side of the rock and soil are controlled within 2cm, and the distance between the closed mesh and the rock and soil after being stretched is ≥2cm, with precise fit and no protrusions or depressions, further improving the effectiveness of protection.

[0019] 4. The closed structure of this invention features a drainage pipe precisely positioned in the fractured rock and soil zone and at the seepage point. Using a 20-50mm diameter pipe, it is installed at a downward angle of 10°-15°, with an insertion depth of ≥12cm into the rock. The pipe is wrapped with filter cloth, has an internal fiber cotton layer, and is reinforced with positioning steel bars. This effectively filters impurities to prevent blockage and directs the discharge of fissure water. It avoids the accumulation of seepage water, which can create water pressure that softens the rock and soil, causing the sealing layer to detach and become hollow. Simultaneously, it reduces water erosion on steel nails and anchor rods, extending the overall service life of the structure.

[0020] 5. The closed structure of this invention uses steel wire binding and hook snapping to replace traditional on-site welding for the supporting grid reinforcement group, reducing construction difficulty and safety hazards of high-altitude operations; the precise installation points of the pre-set bolts on the bolt reinforcement and ribs eliminate the need for secondary marking and hole finding on-site, and the steel nails and anchor bolt components can be directly installed, reducing construction errors and improving assembly efficiency; the closed net and supporting grid reinforcement group can be pre-assembled into an integrated structure, which can be quickly unfolded and flattened after rolling and lowering, adapting to the construction rhythm of layer-by-layer excavation of the foundation pit.

[0021] 6. The closed structure of this invention is specifically designed for fractured rock geological formations such as moderately weathered rock and sandstone. Through the synergistic design of grouting filling, mesh reinforcement, and directional drainage, it perfectly adapts to the support requirements of this type of geological formation. Construction requires no complex equipment, and the materials used are general-purpose materials such as No. 3-6 steel wire and conventional steel mesh / wire mesh. The improved structural stability reduces the frequency of later maintenance and replacement, thus lowering the total life cycle cost. The thickness of the shotcrete can be flexibly adjusted according to the geological conditions, balancing protective effect and economy. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a multi-dimensional protective support pile-interlocking structure according to an embodiment of the present invention; Figure 2 This is a front view of the closed structure between support piles in an embodiment of the present invention; Figure 3 This is a schematic diagram of the installation structure of the drain pipe in an embodiment of the present invention; Figure 4 This is a schematic diagram of the installation structure of the anchor bolt assembly in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the spiral ring rib and the rib in an embodiment of the present invention.

[0023] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1-support pile, 2-cap beam, 3-closed mesh, 4-bolted reinforcing bar, 5-rib, 6-steel nail, 7-anchor assembly, 701-barb, 702-grouting rod, 703-fiberglass self-adhesive tape, 704-threaded cap, 8-drainage pipe, 801-protective cover, 802-fiber cotton layer, 803-pipe body, 804-filter cloth, 805-positioning reinforcing bar, 9-concrete layer, 10-soil and rock between piles. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0025] like Figure 1-5 As shown, this invention provides a multi-dimensional protective retaining pile inter-pil enclosure structure, including retaining piles 1, capping beams 2, enclosure netting 3, support grid reinforcement groups, anchor bolt assemblies 7, drainage pipes 8, and a concrete layer 9. The enclosure netting 3 is located on the free side of the soil and rock between the retaining piles and is made of steel plate mesh or wire mesh. The support grid reinforcement group is a grid-like structure, fixedly connected to the outside of the enclosure netting 3, including spiral ring reinforcement 4 and ribs 5. The spiral ring reinforcement 4 has four sets, connected end-to-end to form a square frame, and steel nails 6 are used to pass through the first spiral ring on the spiral ring reinforcement 4, thereby stretching the edges of the enclosure netting 3 and pressing it onto the retaining piles 1 and capping beams 2 respectively. The ribs 5 have multiple sets that are vertically intersecting to form a grid-like structure, with both ends fixedly connected to the corresponding spiral ring reinforcement 4, and spaced apart on top. Multiple sets of second spiral rings are provided; the anchor bolt assembly 7 passes through the second spiral rings and is installed in the anchor hole opened in the soil-rock 10 between the piles. The multiple sets of arrayed anchor bolt assemblies 7 form an anchoring part that is integrated with the soil-rock 10 between the piles through grouting, and seals the gap between the soil and rock; the drainage pipe 8 is inclined downward and set at the fracture zone and seepage point of the soil-rock 10 between the piles to drain the seepage water in a targeted manner; the concrete layer 9 is sprayed with concrete on the free side of the soil-rock between the support piles to wrap and integrate the closed net 3 and the supporting grid reinforcement group, forming a complete closed net-reinforcement-concrete composite protection system. The closed structure of this invention, through the coordinated design of the closed mesh 3, the supporting grid reinforcement group, the anchor rod assembly 7 and the drainage pipe 8, not only effectively solves the pain points of frequent rockfalls, hollowing and falling off, poor seepage and drainage, and complex construction of traditional inter-pile sprayed structure, but also has the advantages of convenient installation, no need for high-altitude welding, and compatibility with fractured rock geology such as moderately and strongly weathered rock, which greatly improves the stability of the closed structure and the inter-pile soil and rock, while reducing construction safety risks and total life cycle costs.

[0026] In this embodiment of the invention, the support pile 1 is a vertical load-bearing component for foundation pit support, bearing the lateral earth pressure and rock thrust of the foundation pit sidewall, providing a stable vertical support boundary for the pile-to-pile closed structure. It is arranged along the outline of the foundation pit, and a gap is formed between adjacent support piles, which is filled and protected by the closed structure to prevent the rock and soil between piles from falling off.

[0027] The crown beam 2 is a reinforced concrete beam cast on the top of the support pile 1. It connects the discrete support piles 1 laterally into a whole, disperses the force on the individual support piles 1, and improves the integrity and stability of the entire support system.

[0028] In this embodiment of the invention, the closed net 3 is used to intercept falling rocks and soil, transmit anchoring force, and assist in the forming of shotcrete. It is located on the free side of the rock and soil between the support piles, with its two sides braced and fixed to the adjacent support piles 1, its top fixed to the capping beam 2, and its bottom limited at the bottom of the rock and soil 10 between the piles. The closed net 3 is parallel to the core connection surface of the adjacent support piles 1. The closed net 3 is made of wire mesh or steel plate mesh with a mesh size of 1-5cm. The width is 2-3 rows of mesh on each side of the net distance between the piles. After being fixed and braced, it is ≥2cm away from the free surface of the rock and soil between the piles. Furthermore, the free surface of the rock and soil is located on the core connection surface of the adjacent support piles 1, with over-excavation or under-excavation ≤2cm, ensuring that the closed net 3 can accurately fit the contour of the rock and soil without local protrusions or depressions, and avoiding hollow shotcrete due to uneven gaps between the net and the rock and soil.

[0029] The closed net 3 is directly located on the free side of the soil and rock between the support piles, forming the first physical barrier to prevent moderately weathered rock, sandstone, and other fractured rocks from falling off due to sun exposure and rainfall and causing injury. At the same time, the closed net 3 serves as a fixed carrier for the bracing frame reinforcement group, and the two form a net-reinforcement composite skeleton, providing a foundation for subsequent shotcrete formation and preventing the concrete from flowing or bubbling due to lack of support during shotcreting. Furthermore, the closed net 3 is connected to the soil and rock, support piles 1, and capping beam 2 through anchor bolt components 7 and steel nails 6, dispersing and transferring the lateral pressure of the soil and rock to the support system, thereby enhancing the overall stability of the soil and rock between the piles.

[0030] The supporting grid reinforcement group acts on the closed mesh 3, solving the problems of traditional steel mesh being not firmly fixed, unevenly stressed, and complicated in construction; the supporting grid reinforcement group includes spiral ring reinforcement 4 and rib reinforcement 5.

[0031] The spiral reinforcement 4 has four sets, made of No. 3-6 steel wire. A first circular spiral ring with an inner diameter of 1.6-2.5mm is set every 8-12cm. The first circular spiral ring is formed by twisting the steel wire. The four sets of spiral reinforcement 4 are connected end to end to form a square frame, which is used to fix the closed net 3 to the support pile 1 and the capping beam 2, defining the overall outline of the closed net and transmitting boundary constraint force. During the fixation operation, the closed net 3 is stretched and unfolded by the square frame formed by the spiral reinforcement 4, so that it is on the free side of the rock and soil between the support piles. Steel nails 6 are used to pass through the first circular spiral ring and drive into the support pile 1 and the capping beam 2 in sequence. The round cap of the steel nail 6 is used to limit and fix the first circular spiral ring, so that the two sides of the closed net 3 are stretched and fixed to the adjacent support pile 1, the top edge is stretched and fixed to the capping beam 2, and the bottom edge is fixed by driving steel nails 6 into the bottom of the rock and soil 10 between the piles, so that the unfolded surface of the closed net 3 is straight and to prevent the later sprayed concrete from sliding and accumulating at the bottom of the rock and soil 10 between the piles and compressing the bottom edge of the closed net 3 outward. Furthermore, one end of the steel nail 6 has a round cap with a diameter larger than the inner diameter of the first circular helical ring. The nail rod has ribs and is driven into the pile after drilling a hole vertically upward from the side wall of the support pile to the pile core and the bottom of the cap beam. The depth of the nail is ≥10cm and the pull-out force is ≥0.5KN.

[0032] By incorporating spiral reinforcement 4, the problems of traditional steel mesh lacking a fixed frame and being prone to deformation after being stretched are solved. The spiral reinforcement 4, acting as a four-sided frame, ensures the straightness of the closed mesh 3, preventing local dents and bulges caused by soil pressure or impact from shotcrete, and providing stable contour support for the closed mesh 3. At the same time, the first circular spiral rings spaced apart on the spiral reinforcement 4 provide uniform and precise installation points for the steel nails 6, avoiding the cumbersome process of finding and drilling holes on-site when fixing traditional steel mesh, reducing construction errors, and improving installation efficiency.

[0033] In this embodiment of the invention, the ribs 5 are provided in multiple sets, forming a grid structure through vertical interlacing, serving as stiffening ribs for the closed net 3, thereby strengthening the rigidity of the middle area of ​​the closed net and solving the problems of uneven force distribution and uneven unfolding surface after the closed net is opened; the ribs 5 are made of steel wire of the same type as the spiral ring reinforcement, with a second circular spiral ring with an inner diameter of 8-15mm set at intervals of 20-30cm in the middle, and barbs with the outer diameter of the spiral ring reinforcement 4 as the inner diameter at both ends, with a straight section of the barb ≥8cm. By hooking the barbs at both ends of the ribs 5 to the corresponding spiral ring reinforcement 4 and binding them with steel wire, the fixed connection between the ribs 5 and the spiral ring reinforcement 4 is completed.

[0034] By using multiple sets of ribs 5 to form a grid structure through vertical interlacing, the problem of uneven stress and uneven surface after the closed net is opened is solved, avoiding local depressions or bulges caused by the flexibility of the closed net itself, ensuring that the closed net can remain flat during shotcreting, and reducing the risk of displacement under the impact of shotcreting; at the same time, it transmits the rock and soil pressure (such as rockfall impact and lateral pressure of fractured rock) borne by the closed net 3 to the surrounding spiral reinforcement 4, support piles 1, and capping beam 2, avoiding local stress concentration that could lead to damage to the closed net 3; furthermore, the second circular spiral ring in the middle provides a precise installation point for the anchor bolt assembly 7, ensuring the coordinated fixation of the anchor bolt assembly 7 with the closed net 3 and ribs 3, and improving the bonding between the closed structure and the rock and soil.

[0035] The supporting frame reinforcement group is fixed to the outside of the closed mesh 3 by steel wire binding. During the binding operation, the square frame formed by the spiral ring reinforcement 3 is placed on the outside of the closed mesh, ensuring that the spiral ring reinforcement 4 is tightly attached to the closed mesh 3 without any warping or offset, and that the first spiral ring of each group is aligned with the mesh opening of the closed mesh 3; steel wire is used to bind and fix the first spiral ring to the mesh opening of the closed mesh 3, ensuring that the spiral ring reinforcement 4 is tightly attached to the closed mesh 3 without any warping or offset, and the diagonal error of the rectangular frame is ≤3cm; multiple sets of ribs 5 are evenly arranged along the longitudinal or transverse direction of the closed mesh 3, and the ribs are... Both ends of rib 5 extend from the inside of the closed netting, then bend in the opposite direction to form barbs that firmly engage with the spiral ring reinforcement 3. Steel wire is used for binding and fixing, completing the fixed connection between rib 5 and spiral ring reinforcement 3. Steel wire is also used to bind and fix the second spiral ring on rib 5 to the corresponding mesh of the closed netting 3, ensuring complete contact between rib 5 and closed netting 3 to prevent displacement of rib 5 due to impact during shotcreting. For areas with concentrated stress (such as the four corners and the connection between ribs and spiral ring reinforcement), 1-2 additional steel wire bindings are added to ensure the entire structure does not fall apart during rolling and lowering. After assembly and verification, the integrated structure is slowly rolled into a cylindrical shape along the long side (or height) of the closed netting. Twisting of the structure is avoided during rolling to ensure it can quickly return to a flat state after lowering and unfolding, preparing for subsequent fixing to the cap beam 2 and support pile 1. The binding process uses steel wire binding and barbed snap-fit ​​to replace the traditional on-site welding of steel mesh, which reduces the construction difficulty and avoids the safety hazards of high-altitude welding. At the same time, the first and second spiral rings correspond to the corresponding mesh holes on the closed mesh 3, which not only ensures a firm connection, but also provides precise positioning points for the subsequent steel nails 6 and anchor bolt components 7, eliminating the need for secondary marking on-site.

[0036] like Figure 4As shown in the embodiment of the present invention, the anchor bolt assembly 7 is used to improve the overall stability of the soil and rock, strengthen the pull-out resistance and impact resistance of the closed structure, and solve the problems of few fixing points and loose connection of traditional steel mesh. The anchor bolt assembly 7 passes through the second helical ring and is anchored in the soil and rock 10 between piles. It includes barbs 701, grouting rods 702, fiberglass self-adhesive tape 703 and threaded caps 704. One end of the grouting rod 702 passes through the second helical ring and is anchored in the corresponding anchor hole on the soil and rock 10 between piles. It is a hollow rod with a rod diameter smaller than the diameter of the second helical ring. Multiple sets of grouting holes are opened on the rod body for grouting. The barbs 701 are fixed on the outer wall of the grouting rod 702 to achieve mechanical fixation with the inner wall of the anchor hole. The fiberglass self-adhesive tape 703 is wrapped around the rear end of the grouting rod 702 to seal the anchor hole. The threaded cap 704 is threaded to the tail end of the grouting rod 702. Furthermore, the outer diameter of the grouting flower rod 702 is 0.6-1.2mm smaller than that of the second spiral ring, and the wall thickness is 1.2mm. It is inclined upward in the rock and soil 10 between the piles, with an upward inclination angle of 8°-12°, and the length of the rock anchoring end is ≥25cm.

[0037] When installing the anchor bolt assembly 7, the drilling point is marked according to the position of the second helical ring, and a pilot hole is drilled. After drilling, the rock debris in the hole is blown away in time to avoid impurities affecting the anchoring effect. Two layers of fiberglass self-adhesive tape 703 are wrapped around the rear end of the grouting rod 702. After completion, the grouting rod 702 is driven into the anchor hole, and the barbs 701 around the body achieve preliminary mechanical fixation. The fiberglass self-adhesive tape is tightly attached to the wall of the anchor hole to complete the gap sealing. The grouting slurry fills the gap between the hole wall and the grouting rod 702 and seeps into the rock and soil fissures to form the anchoring part, thereby strengthening the bonding between the anchor bolt assembly and the rock and soil.

[0038] By incorporating anchor bolt assembly 7, the flexible closed mesh 3 is firmly fixed to the free side of the soil and rock between piles, avoiding displacement caused by the insecure fixing of traditional steel mesh. At the same time, the distance between the closed mesh 3 and the free surface of the soil and rock is adjusted (ensuring ≥2cm) to reserve uniform space for shotcrete. The anchor bolt assembly 7 serves as a delivery channel for grouting slurry, injecting slurry into the cracks in the soil and rock and the voids between the shotcrete and the soil and rock through the grouting holes. After the slurry solidifies, it forms an anchoring part, filling the voids inside the soil and rock, improving the overall stability of the soil and rock between piles, and eliminating the hidden danger of voids in the closed structure. Furthermore, by passing the anchor bolt assembly 7 through the second spiral ring, it forms a synergistic system of longitudinal anchoring and transverse stiffening with the ribs, preventing the ribs from bending and deforming under the pressure of the soil and rock, and further strengthening the impact resistance of the middle area of ​​the closed mesh.

[0039] like Figure 3As shown in the embodiment of the present invention, the drainage pipe 8 is used to directionally drain water from rock and soil fissures, preventing seepage and soaking that could lead to softening of the rock and soil, and hollowing and detachment of the sealed structure. The drainage pipe 8 includes a protective cover 801, a fiber cotton layer 802, a pipe body 803, a filter cloth 804, and positioning steel bars 805. The pipe body 803 is located in the drainage holes provided on the rock and soil between piles 10, and its pipe body is provided with multiple sets of water inlets. The drainage holes are respectively located at the exposed fracture zone, rock stratum joints, and seepage points after earthwork excavation, and are formed by drilling. The fiber cotton layer 802 is filled inside the pipe body 803; the positioning steel bar 805 is vertically inserted into the pipe body 803 to limit and fix the fiber cotton layer 802. Multiple sets of the positioning steel bar 805 are spaced along the pipe body 803, passing through the water inlet and inserted into the fiber cotton layer 802 for limiting and fixing; the filter cloth 804 is wrapped around the outside of the pipe body 803 to prevent pipe blockage; the protective cover 801 is located at the water outlet of the pipe body 803 to prevent sprayed concrete slurry from entering the pipe. Further, the pipe body 803 has a diameter of 20-50mm, an installation downward tilt angle of 10°-15°, and an insertion depth into the soil or rock ≥12cm.

[0040] When installing the drain pipe 8, mark the drilling points according to the seepage area, and drill drainage holes with an electric drill. The drilling depth should be ≥12cm, and the drilling angle should be strictly controlled to be 10°-15° downward. Wrap 2-3 layers of filter cloth 804 around the outside of the pipe body 803, fill the inside of the pipe with fiber cotton 802, and insert positioning steel bars 805 for limiting and fixing to prevent the fiber cotton 802 from shifting. Insert the pre-treated pipe body 802 into the drainage hole, ensuring that the penetration depth is ≥12cm. Seal the gap between the pipe body 802 and the drainage hole with cement grout to prevent seepage from overflowing from the gap. Finally, put a disposable protective cover 801 on the outlet to complete the installation.

[0041] By incorporating a drainage pipe 8, water from the fissures within the soil and rock can be precisely collected. Then, using the gravity effect with a downward deflection angle of 10°-15°, the seepage water is discharged outside the pile-sealed structure, preventing the accumulation of seepage water between the soil and rock and the shotcrete, which could lead to water pressure buildup and cause the sealing layer to become hollow and fall off. At the same time, it reduces the corrosion of the steel nails and anchor rod components 7 by seepage water, preventing water erosion from causing cracks in the shotcrete and extending the service life of the entire sealing structure.

[0042] The closed structure of this invention forms a mesh-reinforced composite skeleton by supporting the grid reinforcement group and the closed mesh. The spiral reinforcement forms a square frame to define the outline of the closed mesh, and the ribs are vertically intersected to form a grid-like stiffening structure, which solves the problems of uneven stress and easy deformation of the traditional steel mesh. With the help of multiple arrays of anchor bolts, the anchoring part is formed by grouting and is integrated with the rock and soil. This not only achieves a firm connection between the closed mesh and the rock and soil, but also fills the rock and soil cracks. At the same time, it works with the support piles and the capping beam to form a complete stress system, effectively dispersing the lateral pressure of the rock and soil and avoiding structural damage caused by local stress concentration.

[0043] The closed structure of this invention, by incorporating anchor bolt assemblies, combines anchoring and grouting functions. The grout can penetrate into the cracks in the soil and rock, as well as the voids between the sealing mesh and the soil and rock, forming a dense anchoring structure after solidification. This eliminates the void problem caused by the incomplete filling of traditional sprayed mesh protective layers. At the same time, the concrete layer completely encapsulates and integrates the sealing mesh and the supporting grid reinforcement, forming a composite protection system of sealing mesh-reinforcement-concrete. Combined with the pull-out resistance of the anchor bolt assemblies, this significantly reduces the risk of the closed structure falling off due to corrosion and water erosion in the later stages.

[0044] The closed structure of this invention uses a steel wire mesh or steel plate mesh with a mesh size of 1-5cm, which is directly attached to the free side of the rock and soil between piles to form the first physical barrier. This effectively restrains the fractured rock and avoids the problem that traditional large-pore steel mesh cannot intercept falling rocks, significantly reducing the safety risk of rock detachment and injury during construction. Furthermore, the over-excavation or under-excavation of the free side of the rock and soil is controlled within 2cm, and the distance between the closed mesh and the rock and soil after being stretched is ≥2cm, with precise fit and no protrusions or depressions, further improving the effectiveness of protection.

[0045] The closed structure of this invention features a drainage pipe precisely positioned in the fractured rock and soil zone and at the seepage point. Using a 20-50mm diameter pipe, it is installed at a downward angle of 10°-15°, with an insertion depth of ≥12cm into the rock. The pipe is wrapped with filter cloth, has an internal fiber cotton layer, and is reinforced with positioning steel bars. This effectively filters impurities to prevent blockage and directs the discharge of fissure water. It avoids the accumulation of seepage water, which can create water pressure that softens the rock and soil, causing the sealing layer to detach and become hollow. Simultaneously, it reduces water erosion on steel nails and anchor rods, extending the overall service life of the structure.

[0046] The closed structure of this invention uses steel wire binding and hook snapping to replace traditional on-site welding for the supporting grid reinforcement group, reducing construction difficulty and safety hazards of high-altitude operations; the precise installation points of the pre-set bolts on the bolt reinforcement and ribs eliminate the need for secondary marking and hole finding on-site, and the steel nails and anchor bolts can be directly installed, reducing construction errors and improving assembly efficiency; the closed mesh and supporting grid reinforcement group can be pre-assembled into an integrated structure, which can be quickly unfolded and flattened after rolling and lowering, adapting to the construction rhythm of layer-by-layer excavation of foundation pits.

[0047] The closed structure of this invention is specifically designed for fractured rock geological formations such as moderately weathered rock and sandstone. Through the coordinated design of grouting filling, mesh reinforcement, and directional drainage, it perfectly adapts to the support requirements of this type of geological formation. Construction requires no complex equipment, and the materials used are general-purpose materials such as No. 3-6 steel wire and conventional steel mesh / wire mesh. The improved structural stability reduces the frequency of later maintenance and replacement, thus lowering the total life cycle cost. The thickness of the shotcrete can be flexibly adjusted according to the geological conditions, balancing protective effect and economy.

[0048] This invention also provides a construction method for a multi-dimensional protective support pile-sealing structure, comprising the following steps: S1: Plan the layout of the enclosed structural facade based on geological conditions; S2: Select the appropriate size of closed netting 3 according to the layout plan, and use supporting grid reinforcement to tie and fix it to the closed netting 3; S3: Excavate the foundation pit soil and rock layer by layer, with a single excavation depth of ≤3m; control the over-excavation or under-excavation of the soil and rock surface between piles to ≤2cm, and the local over-excavation or under-excavation area to ≤0.1m², to ensure the flatness of the surface. S4: Roll up and lower the pre-assembled closed net 3 and the support grid reinforcement group. First, fix the top of the support grid reinforcement group to the cap beam 2, and release it gradually as the excavation depth increases. Drive the steel nails 6 through the first spiral ring of the spiral reinforcement 3 and into the support piles 1 on both sides. S5: Mark the drilling point according to the position of the second threaded ring on the rib 5 to complete the anchor hole drilling operation; drive the anchor rod assembly 7 through the second threaded ring into the anchor hole, use the barb 701 to fix it initially, and seal the anchor hole gap with fiberglass self-adhesive tape 703. S6: Drill drainage holes at rock and soil fracture zones and seepage points, and insert a drain pipe 8 wrapped with filter cloth 804, an inner fiber cotton layer 802, and positioning steel bars 805 into the drainage holes; seal the gap between the pipe body 803 and the hole wall with cement grout, and cover the outlet with a disposable protective cover 801 to prevent clogging. S7: Spray concrete layer by layer, first spray the connection between the cap beam 2 and the support pile 1, then spray the middle area; ensure that the threaded cap 704 is not covered, forming a concrete layer 9 that wraps the closed net and supports the grid reinforcement group; S8: After the concrete layer 9 has cured, open the threaded cap 704 and connect the grouting pipe; inject concrete grout, control the pressure to 0.3-0.5MPa, and add grout 2-3 times to ensure the filling degree is ≥80%; after grouting, use the threaded cap 704 to seal the end of the grouting flower rod 702; remove the protective cover 801 of the drain pipe 8.

[0049] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-dimensional protective support pile-interlocking structure, characterized in that, include: The closed mesh (3) located on the free side of the rock and soil between the support piles is made of steel plate mesh or steel wire mesh with a mesh size of 1-5cm; The supporting grid reinforcement group fixedly connected to the outside of the closed net (3) includes spiral ring reinforcement (4) and rib reinforcement (5); the spiral ring reinforcement (4) is provided in four groups, which are connected end to end to form a square frame, and steel nails (6) are used to pass through the first spiral ring on the spiral ring reinforcement (4), thereby pulling the edge of the closed net (3) and pressing it onto the support pile (1) and the crown beam (2) respectively; the rib reinforcement (5) is provided in multiple groups and is vertically intersected to form a grid structure, and its two ends are fixedly connected to the corresponding spiral ring reinforcement (4), and multiple groups of second spiral rings are provided on it at intervals; An anchor rod assembly (7) with one end passing through the second spiral ring and inserted into the anchor hole, and multiple sets of arrayed anchor rod assemblies (7) are connected to the rock and soil between the piles (10) by grouting to form an anchoring part and seal the gap between the rock and soil; Drainage pipes (8) are installed at the fracture zone and seepage point of the rock and soil between piles (10) at a downward inclination. And the concrete layer (9), which is formed by spraying concrete onto the free side of the rock and soil between the support piles to wrap and integrate the closed net (3) and the support grid reinforcement group.

2. The multi-dimensional protective support pile-interlocking structure according to claim 1, characterized in that, The first and second spiral rings are aligned with the corresponding mesh openings of the closed mesh (3). The spiral rings are tied and fixed by passing steel wire through the mesh openings of the first spiral ring and the closed mesh (3), so that the spiral ring rib (4) fits tightly with the closed mesh (3). The second spiral ring on the rib (5) is tied and fixed with the corresponding mesh opening of the closed mesh (3) by steel wire, so that the rib (5) fits completely with the closed mesh (3).

3. The multi-dimensional protective support pile-interlocking structure according to claim 2, characterized in that, The rib (5) has barbs at both ends with the outer diameter of the spiral ring rib (4) as the inner diameter. By hooking the barbs at both ends of the rib (5) to the corresponding spiral ring rib (4) and binding them with steel wire, the rib (5) and the spiral ring rib (4) are fixedly connected.

4. A multi-dimensional protective support pile-interlocking structure according to any one of claims 1-3, characterized in that, The steel nail (6) has a round cap at one end, the diameter of which is larger than that of the first circular spiral ring. The nail rod has ribs. The steel nail (6) is used to pass through the first circular spiral ring in sequence and drive into the support pile (1) and the crown beam (2). The round cap of the steel nail (6) is used to limit and compress the first circular spiral ring, so that the two sides of the closed net (3) are respectively stretched and compressed on the adjacent support pile (1), the top edge is stretched and compressed on the crown beam (2), and the bottom edge is driven into the bottom of the rock and soil (10) between the piles by the steel nail (6) for limitation, so that the surface of the closed net (3) is straight.

5. A multi-dimensional protective support pile-interlocking structure according to any one of claims 1-3, characterized in that, The anchor assembly (7) passes through the second helical ring and is anchored in the soil and rock (10) between the piles. It includes a barb (701), a grouting rod (702), a fiberglass self-adhesive tape (703), and a threaded cap (704).

6. The multi-dimensional protective support pile-interlocking structure according to claim 5, characterized in that, One end of the grouting rod (702) passes through the second helical ring and is anchored in the corresponding anchor hole on the inter-pile soil (10). It is a hollow rod with a rod diameter smaller than the diameter of the second helical ring. Multiple sets of grouting holes are opened on the rod body for grouting. The barb (701) is fixed on the outer wall of the grouting rod (702) to achieve mechanical fixation with the inner wall of the anchor hole. The fiberglass self-adhesive tape (703) is wrapped around the rear end of the grouting rod (702) to seal the anchor hole. The threaded cap (704) is threaded to the tail end of the grouting rod (702).

7. The multi-dimensional protective support pile-interlocking structure according to claim 6, characterized in that, The outer diameter of the grouting flower rod (702) is 0.6-1.2 mm smaller than that of the second spiral ring, and the wall thickness is 1.2 mm. It is inclined upward in the rock and soil (10) between the piles, with an upward inclination angle of 8°-12° and a rock anchoring end length ≥25 cm.

8. A multi-dimensional protective support pile-interlocking structure according to any one of claims 1-3, characterized in that, The drainage pipe (8) includes a protective cover (801), a fiber cotton layer (802), a pipe body (803), a filter cloth (804), and positioning steel bars (805); the pipe body (803) is located in the drainage hole provided on the inter-pile rock and soil (10), and its pipe body is provided with multiple sets of water inlets; the drainage holes are respectively located in the fractured zone, rock stratum joint, and seepage point exposed after earthwork excavation, and are obtained by drilling; the fiber cotton layer (802) is filled with Inside the pipe body 803; the positioning steel bar (805) is vertically inserted into the pipe body (803) to limit and fix the fiber cotton layer (802). The positioning steel bar (805) is provided in multiple sets at intervals along the pipe body (803), and is inserted into the fiber cotton layer (802) through the water inlet hole to limit and fix it; the filter cloth (804) is wrapped around the outside of the pipe body (803); the protective cover (801) is provided at the water outlet of the pipe body (803).

9. A multi-dimensional protective support pile-interlocking structure according to claim 8, characterized in that, The pipe body (803) has a diameter of 20-50mm, an installation downward tilt angle of 10°-15°, and an insertion depth into the soil and rock of ≥12cm.

10. A construction method for a multi-dimensional protective support pile-interlocking structure, characterized in that, Includes the following steps: S1: Plan the layout of the enclosed structural facade based on geological conditions; S2: Select the appropriate size of closed net (3) according to the layout plan, and use the support grid reinforcement group to tie and fix it on the closed net (3); S3: Excavate the foundation pit soil and rock layer by layer, with a single excavation depth of ≤3m; control the over-excavation or under-excavation of the soil and rock surface between piles to ≤2cm, and the local over-excavation or under-excavation area to ≤0.1m², to ensure the flatness of the surface. S4: Roll up and lower the pre-assembled closed net (3) and the support grid reinforcement group. First, fix the top of the support grid reinforcement group to the crown beam (2). Release it gradually as the excavation depth increases. Drive the steel nail (6) through the first ring of the spiral reinforcement (4) into the support piles (1) on both sides. S5: Mark the drilling point according to the position of the second helical ring on the rib (5) to complete the anchor hole drilling operation; drive the anchor rod assembly 7 through the second helical ring into the anchor hole, use the barb (701) to fix it initially, and seal the anchor hole gap with fiberglass self-adhesive tape (703); S6: Drill drainage holes at rock and soil fracture zones and seepage points, and insert a drain pipe (8) wrapped with filter cloth (804), an inner fiber cotton layer (802), and positioning steel bars (805) into the drainage holes; seal the gap between the pipe body (802) and the hole wall with cement grout, and cover the outlet with a disposable protective cover (801) to prevent blockage. S7: Spray concrete layer by layer, first spray the connection between the cap beam (2) and the support pile (1), then spray the middle area; ensure that the threaded cap (704) is not covered, and form a concrete layer (9) that wraps the closed net and supports the grid reinforcement group. S8: After the concrete layer (9) has been cured, open the threaded cap (704) and connect the grouting pipe; inject concrete grout, control the pressure to 0.3-0.5MPa, and add grout 2-3 times to ensure the filling degree is ≥80%; after the grouting is completed, use the threaded cap (704) to seal the end of the grouting flower rod (702); remove the protective cover (801) of the drain pipe (8).

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