Underwater pre-stressed anchor rod construction system and construction method

Abstract

The invention relates to an underwater pre-stressed anchor rod construction system and method, and the construction system comprises an orifice pipe which is installed in a preset hole at an orifice of an anchor rod hole in a sealing manner and is used for sealing a gap between a waterproof curtain and a wall protection sleeve at the orifice; the wall protection sleeve penetrates through the orifice pipe and is mounted in the anchor rod hole in the hole forming process of the anchor rod hole; the pre-stressed anchor rod is mounted in the wall protection sleeve after the anchor rod hole is formed; the grouting assembly comprises a grouting outer pipe and a grouting inner pipe, the grouting outer pipe is installed in the wall protection sleeve after the anchor rod hole is formed, a plurality of sets of one-way grout outlet valves are arranged on the pipe wall of the grouting outer pipe at intervals in the axial direction, the grouting inner pipe is movably arranged in the grouting outer pipe, and the end of the grouting inner pipe is connected with a grouting device; and the orifice plug is mounted at the opening part of the wall protection sleeve in a sealing manner, and a penetrating hole is formed in the orifice plug. The system effectively solves the construction problem of the pre-stressed anchor rod under a new environment and a new working condition, is locally optimized on the basis of existing construction equipment, is low in investment and quick in effect, and has economic benefits and social benefits.

Description

Technical Field

[0001] This invention relates to the field of foundation pit support technology in geotechnical engineering, and particularly to the construction of prestressed anchor bolts, specifically to an underwater prestressed anchor bolt construction system and method. Background Technology

[0002] The rapid development and utilization of urban underground space has led to increasingly deeper excavations in foundation pit engineering. Simultaneously, guided by groundwater protection policies at all levels, water resources and the environment have significantly improved, with urban groundwater levels rising year by year. Therefore, the construction of pile-anchor support structures in deep foundation pit engineering inevitably involves addressing the issue of constructing prestressed anchors below the groundwater level, specifically addressing the problems of water and sand inrush during drilling and grout erosion during anchor hole injection. Currently, deep foundation pit engineering primarily employs groundwater control measures consisting of a cutoff wall, a pressure relief well (outside the pit), and a drainage well (inside the pit). Before constructing prestressed anchors, the groundwater outside the cutoff wall is pumped out using pressure relief wells to lower the water level below the design elevation of the prestressed anchors. The prestressed anchors are then constructed in a water-free environment.

[0003] Traditional methods, such as using pressure relief wells and drainage wells to lower the water level, suffer from problems such as water waste, long construction periods, and difficulty in lowering the water level to the design elevation. Especially in water-rich strata, water and sand inrush is prone to occur during borehole drilling, and the grout is washed away by water flow during grouting, seriously affecting the anchoring quality and construction safety.

[0004] Therefore, there is an urgent need to invent an underwater prestressed anchor construction system to cope with the trend of increasingly deeper foundation pits and gradually rising groundwater levels. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the main objective of this invention is to provide an underwater prestressed anchor construction system and method to solve problems such as water and sand inrush during hole drilling and grout loss during grouting, so as to achieve efficient, economical and safe construction of anchors under high water level conditions.

[0006] The technical solution of the present invention is as follows:

[0007] This invention proposes an underwater prestressed anchor construction system, comprising:

[0008] The orifice pipe is installed in a pre-set hole at the orifice of the anchor bolt hole to seal the gap between the water-stop curtain and the protective sleeve at the orifice.

[0009] A protective sleeve is passed through the orifice pipe and installed inside the anchor bolt hole during the anchor bolt hole forming process;

[0010] Prestressed anchor bolts are installed inside the protective sleeve after the anchor bolt holes are formed;

[0011] The grouting assembly includes an outer grouting pipe and an inner grouting pipe. The outer grouting pipe is installed inside the protective sleeve after the anchor bolt hole is formed. Multiple sets of one-way grout outlet valves are spaced apart along the axial direction on its pipe wall. The inner grouting pipe is movably installed inside the outer grouting pipe, and its end is connected to a grouting device.

[0012] An orifice plug is installed to seal the opening of the protective sleeve, and has a through hole thereon;

[0013] During grouting, the inner grouting pipe drives the grouter to align with the first set of one-way grout outlet valves of the outer grouting pipe along the drilling direction to open the grouting. After the grouting is completed, it moves forward to the next set of one-way grout outlet valves to continue grouting, so as to squeeze out the mud and water in the protective sleeve and combine it with the soil layer of the anchor hole after the protective sleeve is pulled out to form a grouting anchor body.

[0014] Preferably, the outer wall of the orifice tube is provided with at least one raised circumferential rib, and the inner wall of the orifice tube is provided with dovetail grooves distributed at intervals, with water-stop rings installed in the grooves.

[0015] Preferably, a certain gap is reserved between the outer wall of the orifice pipe and the inner wall of the preset hole, and the gap is filled with micro-expansion concrete to seal the gap between the water-stop curtain and the protective sleeve.

[0016] Preferably, the grouting outer pipe is composed of multiple PVC pipe sections connected by PVC sleeves, and the end of the last PVC pipe section is sealed.

[0017] Preferably, each set of one-way discharge valves consists of at least two through holes arranged opposite to each other and a rubber sleeve covering the through holes.

[0018] Preferably, the grouting inner tube is formed by multiple sections of galvanized pipe connected by threads; and / or, the front end of the grouting inner tube is threaded to the grouting device, and the rear end is connected to the grouting pump through a pipeline.

[0019] Preferably, the grouting device is a tubular structure with multiple grout discharge holes evenly distributed on its wall, and grout stop plugs are provided at both ends of the grouting device.

[0020] Preferably, the orifice plug is made of a water-swellable material.

[0021] Preferably, the through hole includes a grouting pipe hole and multiple steel strand holes, wherein the grouting pipe hole is located at the center of the hole plug and is suitable for passing through the grouting outer pipe, and the multiple steel strand holes are evenly arranged circumferentially around the outer periphery of the grouting pipe hole and are suitable for passing through multiple steel strands of the prestressed anchor rod.

[0022] This invention also proposes a construction method for the above-mentioned underwater prestressed anchor system, comprising the following steps:

[0023] Holes are made at predetermined positions in the water-stop curtain, and the orifice pipe is installed in the holes, with the central axis position consistent with the central axis of the prestressed anchor rod, and micro-expansion concrete is filled around the perimeter.

[0024] The casing wall protection process is used for drilling. During the drilling process, the casing wall protection is passed through the orifice pipe and installed in the anchor bolt hole until the design depth is reached.

[0025] The prestressed anchor rod is tied and fixed, and the grouting outer pipe is inserted through its center and installed together into the protective sleeve.

[0026] The orifice plug is nested and sealed into the opening of the protective sleeve, so that the steel strand of the prestressed anchor rod and the grouting outer pipe pass through the corresponding holes respectively;

[0027] The grouting device connected to the end of the inner grouting pipe is inserted into the outer grouting pipe. The inner grouting pipe is moved sequentially along the drilling direction so that the grouting device is aligned with each set of one-way grout outlet valves on the outer grouting pipe and grouting is performed in a forward-moving manner.

[0028] After grouting is completed, the protective sleeve is pulled out, allowing the grout to combine with the soil layer of the anchor hole wall to form a grouting anchor body that wraps the prestressed anchor and the grouting outer pipe.

[0029] The advantages of this invention compared to existing technologies are as follows: This invention proposes an underwater prestressed anchor bolt construction system. This system is based on existing construction equipment with local optimization, requiring less investment and yielding quick results, thus combining economic and social benefits. It successfully addresses the construction challenges in deep foundation pits with high water levels. Specifically, it has at least the following practical effects:

[0030] In this invention, the orifice pipe can seal the gap between the water-stop curtain and the protective sleeve, effectively avoiding water inrush, sand inrush or grout loss during the drilling and grouting process, and preventing safety accidents caused by ground settlement around the foundation pit due to construction.

[0031] In this invention, the outer wall of the orifice pipe is provided with a raised circumferential rib. After the micro-expansion concrete is filled, the circumferential rib can better bond with the concrete to form a whole. On the one hand, it extends the groundwater seepage path and plays a role in stopping water flow. On the other hand, it increases the resistance to groundwater pressure and prevents the orifice pipe from slipping, thereby improving construction safety.

[0032] In this invention, the retaining sleeve, the orifice pipe, and the orifice plug together form a multi-layer dynamic sealing system. By setting the prestressed anchor rod and grouting components inside the retaining sleeve, the key grouting process is carried out in its inner cavity. The retaining sleeve, as the core barrier, effectively isolates external groundwater and prevents the grout from being diluted by the incoming water flow, thereby ensuring the final effect of grouting and the forming quality of the anchor body.

[0033] In this invention, the grouting assembly employs a double-layer grouting pipe, a one-way grout outlet valve, and a forward grouting process. The combination of the double-layer grouting pipe and the one-way grout outlet valve creates a closed grouting channel, completely solving the problem of cement grout erosion and loss. The forward grouting process effectively replaces mud and water in the hole and removes air bubbles, ensuring high uniformity and density of the grout body. This guarantees the quality control of the final grout anchor body, providing a durable and stable anchoring force for the prestressed anchor rod and ensuring the safety of the foundation pit support system.

[0034] In this invention, the orifice plug is nested and sealed at the opening of the protective sleeve, thereby sealing the opening of the protective sleeve. This effectively prevents the reverse leakage of cement slurry from the opening of the sleeve during the grouting process, ensuring the stable establishment of pressure in the grouting cavity. This creates the key sealing conditions for the forward grouting process, fundamentally guaranteeing the forming quality and reliability of the grouting anchor.

[0035] It should be understood that the description in the Summary of the Invention is not intended to limit the key or essential features of the embodiments of the present invention, nor is it intended to restrict the scope of the invention. Other features of the invention will become readily apparent from the following description. Furthermore, implementation of any embodiment of the present invention does not imply the simultaneous possession or achievement of multiple or all of the aforementioned beneficial effects. Attached Figure Description

[0036] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0037] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0038] Figure 1This is a structural schematic diagram of an underwater prestressed anchor bolt construction system according to some embodiments of the present invention;

[0039] Figure 2 This is a schematic diagram of the orifice pipe installation according to some embodiments of the present invention;

[0040] Figure 3 This is a schematic diagram of the pressure grouting assembly in some embodiments of the present invention;

[0041] Figure 4 This is a cross-sectional schematic diagram of the orifice tube according to some embodiments of the present invention;

[0042] Figure 5 This is a cross-sectional schematic diagram of the orifice pipe assembly with a water-stop ring according to some embodiments of the present invention;

[0043] Figure 6 These are schematic diagrams of the grouting outer pipe structure according to some embodiments of the present invention;

[0044] Figure 7 This is a schematic diagram of the grouting inner tube structure according to some embodiments of the present invention;

[0045] Figure 8 These are schematic diagrams of the grouting device structure according to some embodiments of the present invention;

[0046] Figure 9 This is a schematic cross-sectional view of the orifice plug according to some embodiments of the present invention;

[0047] Figure 10 This is a schematic diagram of the installation of an underwater prestressed anchor bolt construction system according to some embodiments of the present invention;

[0048] Figure 11 This is a construction process flow diagram of an underwater prestressed anchor system according to a specific embodiment of the present invention.

[0049] Marked in the image:

[0050] 1-Orifice pipe; 101-Circumferential rib; 102-Dovetail groove; 103-Waterstop ring;

[0051] 2-Sheath sleeve;

[0052] 3-Prestressed anchor bolt; 301-Steel strand;

[0053] 4- Grouting outer pipe; 401- One-way grout outlet valve; 4011- Through hole; 4012- Rubber sleeve;

[0054] 5- Grouting inner pipe;

[0055] 6- Grouting device; 601- Grout outlet; 602- Grout stop plug;

[0056] 7-Hole plug; 701-Grouting pipe hole; 702-Steel strand hole;

[0057] 8-Micro-expansion concrete;

[0058] 9- Still water curtain;

[0059] 10-Cement grout;

[0060] 11-Muddy water;

[0061] 12-Connecting sleeve;

[0062] 13-Thread.

[0063] The same or corresponding marks in the diagram indicate the same or corresponding parts. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0065] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0066] It should be understood that the terms "comprising / including," "consisting of," or any other variations are intended to cover non-exclusive inclusion, such that a product, apparatus, process, or method that comprises a list of elements includes not only those elements but may also include, where necessary, other elements not expressly listed, or elements inherent to such a product, apparatus, process, or method. Without further limitation, an element defined by the phrases "comprising / including," "consisting of," does not exclude the presence of additional identical elements in the product, apparatus, process, or method that includes said element.

[0067] It should also be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device, component or structure referred to must have a specific orientation, be constructed or operated in a specific orientation, and should not be construed as a limitation of the present invention.

[0068] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0069] This invention proposes an underwater prestressed anchor construction system to solve the problem of constructing prestressed anchors below the groundwater level in the current construction of deep foundation pit pile anchor support structures, namely, solving the problems of water and sand inrush during hole drilling and grout erosion and loss during anchor hole grouting.

[0070] The implementation of the present invention will be described in detail below with reference to preferred embodiments.

[0071] like Figures 1 to 10 As shown, the present invention proposes an underwater prestressed anchor construction system, which consists of an orifice pipe 1, a retaining sleeve 2, a prestressed anchor 3, a grouting assembly, and an orifice plug 7.

[0072] The orifice pipe 1 is made of specific specifications and materials. The orifice pipe 1 is sealed and installed in a pre-set hole at the opening of the anchor bolt hole, for example, it is fixedly embedded in a pre-set hole in the sidewall of the foundation pit. It is easy to understand that the sidewall of the foundation pit is usually a type of water-stop curtain 9 such as a continuous wall, plain concrete pile, cement-soil mixing pile or high-pressure jet grouting pile.

[0073] The retaining sleeve 2 passes through the orifice pipe 1 and is installed inside the anchor hole during the anchor hole drilling process. The prestressed anchor 3 is installed inside the retaining sleeve 2 after the anchor hole is drilled. In this invention, the pre-set hole is specifically designed for installing the orifice pipe 1. Specifically, a downward-sloping pit is chiseled out at the anchor design position of the waterstop curtain 9 according to the anchor's inclination angle, and the inner diameter of the pit is slightly larger than that of the orifice pipe 1.

[0074] In this invention, the main function of the orifice pipe 1 is to seal the gap between the water-stop curtain 9 at the end of the anchor bolt hole and the protective sleeve 2 during the construction of the prestressed anchor bolt 3, so as to prevent water, sand or grout leakage between the hole wall and the outer wall of the sleeve.

[0075] See also Figure 2 A certain gap is reserved between the outer wall of the orifice pipe 1 and the inner wall of the pre-set hole, and this gap is filled with micro-expansion concrete 8. The micro-expansion concrete 8 expands slightly during the solidification process, which can tightly fill the gap between the orifice pipe 1 and the hole, forming a reliable barrier. This helps to prevent groundwater from seeping in through the gap, avoid water and sand inrush problems during drilling or grouting, thereby reducing the risk of ground settlement around the foundation pit and improving construction safety.

[0076] See Figures 4 to 5 The orifice tube 1 has a cylindrical structure, and the outer wall of the orifice tube 1 is provided with two raised circumferential ribs 101. Furthermore, the inner wall of the orifice tube 1 has multiple dovetail grooves 102 distributed at intervals, and water-stop rings 103 can be installed in the dovetail grooves 102.

[0077] In this embodiment, the circumferential rib 101 can extend the groundwater seepage path, thereby playing a good role in water stoppage, reducing the interference of groundwater on the foundation pit construction, and ensuring the dryness and safety of the working environment inside the foundation pit. On the other hand, it enhances the pull-out resistance and impact resistance of the orifice pipe 1 under complex geological conditions and underwater environment, preventing the orifice pipe 1 from slipping or shifting during construction.

[0078] The dovetail groove 102 provides a clear installation position for the water-stop ring 103. During the installation of the orifice pipe 1, the water-stop ring 103 can be accurately placed in the dovetail groove 102, ensuring that the installation position of the water-stop ring 103 meets the design requirements and avoiding the impact on the water-stopping effect due to installation position deviation.

[0079] As is easily understood, the water-stop ring 103 is made of a waterproof material with elasticity and durability (such as water-swellable rubber). Its cross-section is dovetail-shaped to match the dovetail groove 102, and it is firmly engaged in the dovetail groove 102 by pressing or embedding, forming a mechanical interlock, which effectively prevents it from falling off due to water flow impact or friction during the installation or use of the orifice pipe 1.

[0080] During installation, the space between the orifice pipe 1 and the water-stop curtain 9 is filled with micro-expansion concrete 8, and the circumferential rib plate 101 is embedded in the micro-expansion concrete 8. The raised structure of the circumferential rib plate 101 increases the contact area and friction with the micro-expansion concrete 8, making the bond between the orifice pipe 1 and the micro-expansion concrete 8 tighter, improving the density of the filling, and further enhancing the water-stopping and stabilizing effect.

[0081] Furthermore, when installing the orifice pipe 1, it must be consistent with the design position and angle of the prestressed anchor rod 3. Before installation, a downward-sloping pit should be chiseled out in the water-stop curtain 9 according to the design position and angle of the anchor rod. The inner diameter of the pit should be 50-100mm larger than the outer diameter of the circumferential rib plate 101 to leave enough working space to ensure that the micro-expansion concrete 8 can be filled densely.

[0082] The casing 2 adopts the casing wall protection hole forming process. The first section of the casing is 1000mm long, and the remaining casings are 2000mm each. The threaded connection joint is connected as drilling progresses. The excavated soil is discharged to the outside of the hole with the water flow, and the drilling is circulated to the design depth.

[0083] In this invention, the retaining sleeve 2, the orifice pipe 1, and the orifice plug 7 together constitute a multi-layer dynamic sealing system. By setting the prestressed anchor rod 3 and the grouting assembly inside the retaining sleeve 2, the key grouting process is carried out in its inner cavity, effectively isolating external groundwater and preventing the cement grout from being diluted by the incoming water flow, thereby ensuring the final effect of grouting and the forming quality of the anchor body.

[0084] In this invention, the prestressed anchor rod 3 is a conventional existing technology component in the fields of geotechnical engineering and slope protection. It typically comprises the following core parts: a cable body composed of multiple high-strength steel strands or prestressed steel bars, used to provide the main anchoring tension; an anchor at the end of the anchor rod, used to lock and apply prestress; and anchor rod supports (or centering supports) spaced along the length of the anchor rod, whose function is to ensure that the steel strands are centered within the borehole and to form a uniform and complete protective layer around the grout. It is understood that the prestressed anchor rod 3 may also include other conventional auxiliary components, such as grouting pipes, venting pipes, and sleeves at the free section. Its specific structure, materials, and construction process are well known to those skilled in the art and will not be elaborated here.

[0085] The fabrication of prestressed anchor bolts 3 must strictly adhere to design parameters, including key indicators such as the number and length of steel strands, support spacing, and free section length. The number of steel strands is determined based on the pit depth and load calculations to ensure sufficient tensile strength of the anchor bolt. The length includes the free section and the anchoring section. The free section length allows the anchor bolt to deform within a certain range to release stress, while the anchoring section length ensures effective bonding with the grouting body. The support spacing is maintained by evenly distributing centered supports to keep the steel strands parallel and prevent them from tangling. These parameters collectively ensure the structural reliability and mechanical properties of the anchor bolt, conforming to industry standards and specifications.

[0086] See also Figures 1 to 3 The grouting assembly includes an outer grouting pipe 4 and an inner grouting pipe 5. The outer grouting pipe 4 is installed inside the protective sleeve 2 after the anchor bolt hole is formed. Multiple sets of one-way grout outlet valves 401 are distributed axially along its pipe wall. The inner grouting pipe 5 is movably installed inside the outer grouting pipe 4 and its end is connected to a grouting device 6.

[0087] During grouting, the inner grouting pipe 5 drives the grouter 6 to sequentially align with each set of one-way grout outlet valves 401 of the outer grouting pipe 4 for forward grouting along the drilling direction of the anchor bolt hole. This method can squeeze out the mud and water in the protective sleeve 2, and after the protective sleeve 2 is pulled out, the cement grout 10 combines with the soil layer of the anchor bolt hole wall to form a grouting anchor body.

[0088] More precisely, during grouting, the inner grouting pipe 5 drives the grouter 6 to align with the first set of one-way grout outlet valves 401 of the outer grouting pipe 4 along the drilling direction of the anchor bolt hole to open the grouting. After the grouting is completed, it is pushed forward to the next set of one-way grout outlet valves 401 to continue grouting, so as to squeeze out the mud and water in the protective sleeve 2 and combine with the soil layer of the anchor bolt hole after the protective sleeve 2 is pulled out to form a grouting anchor body.

[0089] In this invention, the one-way grout outlet valve 401 ensures that the cement grout 10 can only overflow from the grouting outer pipe 4, and will not be diluted or backflowed by groundwater, thereby reducing material waste and environmental pollution, solving the problem of cement grout loss during anchor hole grouting, and especially avoiding the risk of insufficient strength of the grout body under high pressure water level environment.

[0090] See also Figure 3 In this invention, grouting adopts a forward grouting method. The grouting device 6 first aligns with the first set of one-way grout outlet valves 401 of the grouting outer pipe 4 and begins to inject cement grout 10, forcing the cement grout 10 to flow out of the one-way grout outlet valves 401. Then, the grouting device 6 is advanced forward according to the spacing of the one-way grout outlet valves 401, and after advancement, cement grout 10 is injected into the second set of one-way grout outlet valves 401. The forward grouting method can use the pressurized cement grout 10 to squeeze out the mud and water 11 in the protective sleeve 2 and diffuse it into the soil around the bottom of the hole. This avoids the voids or incomplete compaction that may be caused by traditional one-time grouting, ensures that the grouting anchor body is evenly bonded to the soil layer, and improves the pull-out force of the anchor rod.

[0091] More specifically, the grouting assembly employs a double-layer grouting pipe, a one-way grout outlet valve, and a forward grouting process. The combination of the double-layer grouting pipe and the one-way grout outlet valve creates a closed grouting channel, completely solving the problem of cement grout erosion and loss. The forward grouting process effectively replaces mud and water in the hole and removes air bubbles, ensuring high uniformity and density of the grout body. This guarantees the quality control of the final grout anchor body, providing a durable and stable anchoring force for the prestressed anchor rod and ensuring the safety of the foundation pit support system.

[0092] In some embodiments, see Figure 6 The grouting outer pipe 4 is composed of multiple PVC pipe sections connected by connecting sleeves 12. The connecting sleeves 12 are PVC sleeves, and their inner diameter matches the outer diameter of the PVC pipes. This segmented design (e.g., each segment is 3000mm long) overcomes the difficulties of transporting and handling long pipes on-site, making it particularly suitable for foundation pit sites with limited space. During construction, pipe sections can be flexibly connected according to the anchor bolt design depth, avoiding operational inconvenience caused by excessively long single pipes.

[0093] In this invention, the grouting outer pipe 4 is made of PVC pipe in sections, and the sections are connected by PVC sleeves. It is inserted into the grouting pipe hole at the center of the hole plug 7 and the anchor rod support, and is installed into the anchor rod hole together with the prestressed anchor rod 3.

[0094] Furthermore, the end of the grouting outer pipe 4 is a closed blind end, that is, the end of the last PVC pipe in the multi-segment PVC pipe of the grouting outer pipe 4 is closed. The blind end design ensures the uniqueness of the grout flow path, avoids disorderly leakage of grout from the pipe end, ensures that the grout fills the annular space between the protective sleeve and the borehole wall in the designed sequence, and prevents the injected cement grout 10 from flowing out of the grouting outer pipe 4 in the reverse direction.

[0095] In some embodiments, see continue to see Figure 6 Each set of one-way grout outlet valves 401 consists of at least two through holes 4011 arranged opposite to each other and a rubber sleeve 4012 wrapped around the through hole 4011. Under the action of grouting pressure, the rubber sleeve 4012 opens, and the cement grout 10 can overflow from the grouting outer pipe 5 along the grouting device 6 and fill the gap between the protective sleeve 2 and the grouting outer pipe 5.

[0096] The bidirectional through-hole layout 4011 ensures uniform diffusion of the cement grout 10 under grouting pressure, while the elastic properties of the rubber sleeve 4012 allow it to open and release the grout under pressure, automatically closing when the pressure decreases. This effectively prevents groundwater from seeping back or grout from being lost, thereby improving the reliability and material economy of grouting. Furthermore, the use of a single-drilling process to achieve dual-hole penetration significantly improves processing efficiency and ease of operation.

[0097] In one specific embodiment, the grouting outer pipe 4 is made of PVC pipe, with bidirectional through holes 4011 (5mm in diameter) spaced at regular intervals (1000mm) on the pipe wall. The outside of the through holes 4011 is covered and wrapped with a rubber sleeve 4012 to form a one-way grout outlet valve 401. Each section of the grouting outer pipe 4 is 3000mm long and is fitted with a large-diameter PVC pipe. The inner diameter of the PVC sleeve is the same as the outer diameter of the grouting outer pipe, and the length is 100mm. The front end of the grouting outer pipe 4 is sealed with a pipe cap and firmly glued.

[0098] In some embodiments, see Figure 7 The grouting inner pipe 5 is composed of multiple sections of galvanized pipe connected segment by segment by thread 13. Furthermore, the front end of the grouting inner pipe 5 is connected to the grouting device 6 via thread 13, and the rear end is connected to the grouting pump via a pipeline. The grouting pump provides a stable pressure source, enabling the cement grout 10 to be efficiently delivered to the grouting device 6 through the threaded galvanized inner pipe, and the pressure drives the grout to overflow from the one-way grout outlet valve 401.

[0099] See Figure 8The grouting device 6 is a tubular structure with multiple grout outlet holes 601 evenly distributed on its pipe wall, and grout stop plugs 602 are installed at both ends of the grouting device 6. More precisely, the grout outlet holes 601 are evenly distributed on the pipe wall of the grouting device, and grout stop plugs 602 are installed at both ends. The end of the grouting device 6 is connected to the inner grouting pipe 5 via a thread 13. The cement grout 10 transported by the inner grouting pipe 5 flows into the outer grouting pipe 4 from the grout outlet holes 601, and can only flow into the inner cavity of the protective sleeve 2 through the one-way grout outlet valve 401 of the outer grouting pipe 4.

[0100] The uniform layout of the multiple grout outlets 601 ensures that the cement grout 10 can continuously and dispersedly overflow during the grouting process. By keeping the outlets behind the interface between the cement grout 10 and the mud-water during grouting, complete replacement can be achieved, preventing mud inclusion. The sealing effect of the grout stop plug 602, working in conjunction with the grout outlets 601, supports the smooth implementation of the forward grouting process. The grout injector 6 advances segment by segment under the push of the grouting inner tube 5. The grout stop plug 602 ensures that the grout can only flow out directionally through the outlets 601, gradually replacing the mud-water 11 within the protective sleeve 2 and avoiding groundwater interference. This pressure-controllable grouting method not only improves construction adaptability, but also reduces the risk of grouting interruption, especially in high water level environments, ensuring project progress.

[0101] In some embodiments, the grouting device 6 is 500 mm long. This size is optimized to balance ease of operation and grouting quality: if the length is too long, the grouting device may cover two adjacent rows of check valves, causing mud and sand to mix into the grout and affecting the reinforcement effect; if the length is too short, it is difficult to accurately align the check valves, increasing the construction difficulty. The 500 mm length avoids the risk of covering and ensures precise docking between the grouting device and the check valves, thereby improving grouting efficiency and project quality.

[0102] See also Figures 1 to 3 The orifice plug 7 is nested and sealed within the opening of the protective sleeve 2, and has a through hole. Further, the through hole includes a grouting pipe hole 701 and multiple steel strand holes 702. The grouting pipe hole 701 is located at the center of the orifice plug 7 and is suitable for inserting the grouting outer pipe 4. The multiple steel strand holes 702 are evenly arranged circumferentially around the outer periphery of the grouting pipe hole 701 and are suitable for inserting multiple steel strands 301 of the prestressed anchor rod 3.

[0103] See Figure 9 The orifice plug 7 has a grouting pipe hole 701 and four anchor bolt holes 702. The grouting pipe hole 701 is located at the center of the orifice plug 7, and the four anchor bolt holes 702 are evenly arranged around the outer periphery of the grouting pipe hole 701.

[0104] The grouting pipe hole 701 is centrally located, allowing the grout to radiate evenly outwards from the center during grouting operations. This ensures the density and uniformity of the grout filling in each area of ​​the hole, significantly improving the overall sealing and load-bearing capacity of the structure. The four anchor holes 702 are evenly arranged in a circle around the grouting pipe hole, which can efficiently disperse external loads and transfer them to the surrounding soil and rock, enhancing the structure's resistance to deformation and slippage.

[0105] The orifice plug 7 is cylindrical and made of a water-swellable material. Its cross-section is as follows: Figure 9 As shown. The grouting pipe hole 701 at the center of the orifice plug 7 is used to insert the grouting outer pipe 4, and the anchor bolt holes 702 at the periphery are used to insert the steel strands 301 (the number of anchor bolt holes 702 is consistent with the number of steel strands in the prestressed anchor design). The inner diameters of the grouting pipe holes 701 and anchor bolt holes 702 are determined by testing based on the outer diameters of the grouting outer pipe and steel strands, as well as the water expansion rate of the material used for the orifice plug, to ensure a sealing effect after sufficient expansion.

[0106] In this invention, after the orifice plug 7 is assembled with the steel strand 301 and the grouting outer pipe 4 and installed into the protective sleeve 2, the inner cavity of the outer end of the protective sleeve 2 is sealed by utilizing the property of the material to expand when it comes into contact with water, so as to prevent the cement grout 10 from being washed away.

[0107] More specifically, the orifice plug 7 is nested and sealed at the opening of the protective sleeve 2, thereby sealing the opening of the protective sleeve 2. This effectively prevents the cement slurry 10 from flowing back from the opening of the sleeve during the grouting process, ensuring the stable establishment of pressure in the grouting cavity. This creates the key sealing conditions for the forward grouting process, fundamentally guaranteeing the forming quality and reliability of the grouting anchor.

[0108] This invention also proposes a construction method for the above-mentioned underwater prestressed anchor system, comprising the following steps:

[0109] Holes are opened at predetermined positions on the sidewall of the foundation pit (water-stop curtain 9), and the orifice pipe 1 is installed in the hole. The central axis position is consistent with the central axis of the prestressed anchor rod 3, and micro-expansion concrete 8 is filled around it.

[0110] The casing wall protection process is used for drilling. During the drilling process, the casing 2 is passed through the borehole pipe 1 and installed in the anchor bolt hole until the design depth is reached.

[0111] The prestressed anchor rod 3 is tied and fixed, and the grouting outer pipe 4 is inserted through its center and installed into the protective sleeve 2 together.

[0112] The orifice plug 7 is nested and sealed in the opening of the protective sleeve 2, so that the steel strand 301 of the prestressed anchor rod 3 and the grouting outer pipe 4 pass through the corresponding holes respectively;

[0113] The grouting device 6 connected to the end of the grouting inner pipe 5 is inserted into the grouting outer pipe 4. The grouting inner pipe 5 is moved sequentially along the drilling direction of the protective sleeve 2 so that the grouting device 6 is aligned with each set of one-way grout outlet valves 401 on the grouting outer pipe 4 to inject grout, thereby squeezing out the mud and water in the protective sleeve 2.

[0114] After grouting is completed, the protective sleeve 2 is pulled out, allowing the grout to combine with the soil layer of the anchor hole wall. After solidification, it forms a grouting anchor body that wraps the prestressed anchor rod 3 and the grouting outer pipe 4.

[0115] Through the above construction method, the present invention achieves the following beneficial effects:

[0116] First, the embedded connection between the orifice pipe and the water-stop curtain effectively stopped and stabilized the orifice. Second, the follow-up drilling of the retaining casing ensured the quality of borehole formation in complex strata. Most importantly, the coordination of one-way grout outlet valves on the inner and outer grouting pipes enabled sequential, segmented grouting from the inside out, completely squeezing out the mud and water within the retaining casing. This fundamentally ensured the fullness, uniformity, and high strength of the grouting anchor body, significantly improving the final bearing capacity and long-term durability of the underwater prestressed anchor. The entire method is clear, highly collaborative, and possesses high construction reliability and efficiency.

[0117] In one specific embodiment, see Figure 11 The specific construction process of the underwater prestressed anchor system of the present invention includes the following steps:

[0118] (1) Construction preparation: Personnel, machinery and materials are brought to the site and inspected / retested; familiarize themselves with the construction drawings and construction plan; complete the plan briefing, safety technical briefing and three-level safety education; and level the site.

[0119] (2) Measurement and positioning: Determine the center point of the prestressed anchor rod 3 according to the construction drawings, and mark the cross lines in the longitudinal and transverse directions, and report to the quality inspector and supervisor.

[0120] (3) Installation of the orifice pipe: A pit for installing the orifice pipe 1 is excavated at the position of the prestressed anchor 3 on the water-stop curtain 9. The angle of the central axis is consistent with the incident angle of the anchor. The inner diameter of the pit is 50~100mm larger than the outer diameter of the circumferential rib plate 101, leaving sufficient working space for filling the micro-expansion concrete 8. Install the orifice pipe 1 to the design position, with the central axis position consistent with the central axis of the anchor. Fill the surrounding area with micro-expansion concrete 8 and compact it.

[0121] (4) Drilling rig positioning: Move the casing anchor drilling rig to the working face, adjust the drilling rig so that its drill bit is aligned with the center of the prestressed borehole pipe 1 (i.e., the anchor bolt injection point), and adjust the drill rod angle to the anchor bolt design angle. Connect the water and electrical circuits, and run the drilling rig idle to test it to normal working condition.

[0122] (5) Drilling: The casing wall forming process is adopted. The first section of the casing 2 is 1000mm long, and the remaining casing 2 sections are 2000mm long. The threaded connection joint is connected as drilling progresses. The excavated soil is discharged to the outside of the hole with the water flow and the drilling is circulated to the design depth.

[0123] (6) Grouting outer pipe processing: The grouting outer pipe 4 is made of PVC pipe. The pipe wall is provided with bidirectional through holes 4011 (5mm in diameter) at certain intervals (1000mm). The outside of the through holes 4011 is covered and wrapped with rubber sleeves 4012 to form a one-way grout outlet valve 401. Each section of the grouting outer pipe 4 is 3000mm long and is connected with a large-diameter PVC pipe. The inner diameter of the PVC sleeve is the same as the outer diameter of the grouting outer pipe, and the length is 100mm. The front end of the grouting outer pipe is sealed with a pipe cap and glued firmly.

[0124] (7) Anchor rod fabrication: Anchor rods are fabricated according to the design requirements for the number, length, bracket spacing, free section length, etc., and the grouting outer pipe 4 is inserted into the center hole and tied securely.

[0125] (8) Anchor installation: Immediately after the drill rod is pulled out, the anchor rod is installed to the design position, and at the same time, the distance L between the last one-way grout outlet valve 401 of the grouting outer pipe 4 and the pipe opening of the protective sleeve 2 is recorded.

[0126] (9) Installation of the orifice plug: Align the reserved hole of the orifice plug 7 with the steel strand 301 and the grouting outer pipe 4, push it into the inner wall sleeve 2 200mm and fix it to prevent it from being pulled out of the sleeve by water pressure.

[0127] (10) Forward grouting: Connect the grouter 6, the inner grouting pipe 5 and the grouting pump. After pushing the grouter 6 to the distance L of the outer grouting pipe 4, turn on the grouting pump to inject cement grout 10. Then, according to the spacing of 1000mm between the one-way grouting valves 401, push forward to the next set of one-way grouting valves 401 for grouting. Continue grouting in this manner until the bottom of the hole.

[0128] (11) Pulling out the protective sleeve: After grouting to the bottom of the anchor hole, pull out the grouting inner tube 5 and start pulling out the protective sleeve 2. The 1000mm long sleeve is left at the hole opening and is sealed with the hole opening tube 1 and the hole opening plug 7.

[0129] In this step, after grouting to the bottom of the anchor hole, the grout at the bottom of the hole is allowed to stand until it initially solidifies to form an early anchoring section. Then, the grouting inner pipe 5 is pulled out. When the protective sleeve 2 is pulled out, in order to ensure that the hole plug 7 and the steel strand 301 are not pulled out, the present invention adopts the following feasible method:

[0130] First, the connection between the orifice plug 7 and the wall-mounted sleeve 2 is a controllable separation structure (e.g., friction clamp or elastic snap-fit). This design ensures sealing and fixation under grouting pressure, but allows for smooth separation under pull-out force, so that the pull-out force acts only on the sleeve itself. Second, the pre-formed bottom grout anchoring section provides pull-out resistance for the steel strand, further ensuring its stability. With this dual protection, the wall-mounted sleeve 2 is pulled out until only a 1000mm long sleeve remains at the orifice. This remaining sleeve, the orifice pipe 1, and the orifice plug 7 maintain a reliable seal through sealing rings.

[0131] (12) Grouting: Reinstall the grouting inner pipe 5 and continue to use the forward grouting method for grouting. The grouting pressure should be such that the one-way grouting valve 401 can be opened. After completion, pull out the grouting inner pipe 5 and fill the grouting outer pipe 4 with cement grout using the normal pressure grouting method.

[0132] (13) After the grout strength reaches 75% of the design value, the anchor rod is tensioned and locked.

[0133] The underwater prestressed anchor construction system proposed in this invention can achieve:

[0134] In this invention, the structural design and installation method of the orifice pipe solve the problems of water and sand inrush during underwater prestressed anchor drilling, and avoid safety accidents caused by ground settlement around the foundation pit due to construction.

[0135] In this invention, the double-layer grouting pipe and one-way grout outlet valve design seals the grouting space of the prestressed anchor rod, solving the problem of cement grout being washed away.

[0136] In this invention, the forward grouting method replaces the mud and water in the anchor bolt hole with cement grout, thus ensuring the quality of anchor bolt grouting.

[0137] The underwater prestressed anchor construction system and method proposed in this invention can effectively solve the construction problems of prestressed anchors under new environments and working conditions.

[0138] The underwater prestressed anchor construction system and method proposed in this invention are based on local optimization and adjustment of existing prestressed anchor construction equipment and processes. Existing equipment can still be used, requiring less investment and yielding quick results, resulting in significant economic and social benefits.

[0139] It will be readily understood by those skilled in the art that, without conflict, the above-mentioned preferred solutions can be freely combined and superimposed.

[0140] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An underwater prestressed anchor bolt construction system, characterized in that, include: The orifice pipe is installed in a pre-set hole at the orifice of the anchor bolt hole to seal the gap between the water-stop curtain and the protective sleeve at the orifice. A protective sleeve is passed through the orifice pipe and installed inside the anchor bolt hole during the anchor bolt hole forming process; Prestressed anchor bolts are installed inside the protective sleeve after the anchor bolt holes are formed; The grouting assembly includes an outer grouting pipe and an inner grouting pipe. The outer grouting pipe is installed inside the protective sleeve after the anchor bolt hole is formed. Multiple sets of one-way grout outlet valves are spaced apart along the axial direction on its pipe wall. The inner grouting pipe is movably installed inside the outer grouting pipe, and its end is connected to a grouting device. An orifice plug is installed to seal the opening of the protective sleeve, and has a through hole thereon; During grouting, the inner grouting pipe drives the grouter to align with the first set of one-way grout outlet valves of the outer grouting pipe along the drilling direction to open the grouting. After the grouting is completed, it moves forward to the next set of one-way grout outlet valves to continue grouting, so as to squeeze out the mud and water in the protective sleeve and combine it with the soil layer of the anchor hole after the protective sleeve is pulled out to form a grouting anchor body.

2. The underwater prestressed anchor construction system according to claim 1, characterized in that, The outer wall of the orifice tube is provided with at least one raised circumferential rib, and the inner wall of the orifice tube is provided with dovetail grooves distributed at intervals, with water-stop rings installed in the grooves.

3. The underwater prestressed anchor construction system according to claim 1, characterized in that, A certain gap is reserved between the outer wall of the orifice pipe and the inner wall of the preset hole. The gap is filled with micro-expansion concrete to seal the gap between the water-stop curtain and the protective sleeve.

4. The underwater prestressed anchor construction system according to claim 1, characterized in that, The grouting outer pipe is composed of multiple PVC pipe sections connected by PVC sleeves, with the end of the last PVC pipe section sealed.

5. The underwater prestressed anchor construction system according to claim 1, characterized in that, Each set of one-way discharge valves consists of at least two through holes arranged opposite to each other and a rubber sleeve covering the through holes.

6. The underwater prestressed anchor construction system according to claim 1, characterized in that, The grouting inner tube is composed of multiple sections of galvanized pipe connected by threads; and / or, the front end of the grouting inner tube is threadedly connected to the grouting device, and the rear end is connected to the grouting pump through a pipeline.

7. The underwater prestressed anchor construction system according to claim 1, characterized in that, The grouting device is a tubular structure with multiple grout discharge holes evenly distributed on its wall, and grout stop plugs are provided at both ends of the grouting device.

8. The underwater prestressed anchor construction system according to claim 1, characterized in that, The orifice plug is made of a water-swellable material.

9. The underwater prestressed anchor construction system according to claim 1, characterized in that, The through hole includes a grouting pipe hole and multiple steel strand holes. The grouting pipe hole is located at the center of the hole plug and is suitable for inserting the grouting outer pipe. The multiple steel strand holes are evenly arranged circumferentially around the outer periphery of the grouting pipe hole and are suitable for inserting multiple steel strands of the prestressed anchor rod.

10. A construction method for an underwater prestressed anchor system according to any one of claims 1 to 9, characterized in that, Includes the following steps: Holes are made at predetermined positions in the water-stop curtain, and the orifice pipe is installed in the holes, with the central axis position consistent with the central axis of the prestressed anchor rod, and micro-expansion concrete is filled around the perimeter. The casing wall protection process is used for drilling. During the drilling process, the casing wall protection is passed through the orifice pipe and installed in the anchor bolt hole until the design depth is reached. The prestressed anchor rod is tied and fixed, and the grouting outer pipe is inserted through its center and installed together into the protective sleeve. The orifice plug is nested and sealed into the opening of the protective sleeve, so that the steel strand of the prestressed anchor rod and the grouting outer pipe pass through the corresponding holes respectively; The grouting device connected to the end of the inner grouting pipe is inserted into the outer grouting pipe. The inner grouting pipe is moved sequentially along the drilling direction so that the grouting device is aligned with each set of one-way grout outlet valves on the outer grouting pipe and grouting is performed in a forward-moving manner. After grouting is completed, the protective sleeve is pulled out, allowing the grout to combine with the soil layer of the anchor hole wall to form a grouting anchor body that wraps the prestressed anchor and the grouting outer pipe.

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