A stress absorption construction device and method for active prevention and control of gravity dam cracks

Abstract

The present invention proposes a stress absorption construction device and method for active prevention and control of cracks in gravity dams, belonging to the field of gravity dam technology. The construction device includes a device body, which includes a second tube body, and a tube wall is provided with at least one group of holes consisting of a plurality of through holes. The second tube body is provided with a strip plate inside, and the strip plate is provided with a plurality of column heads that can be adapted to be plugged into the through holes, and the column heads are provided with compression springs; the construction method includes: S1. Construction preparation, S2. Foundation treatment, S3. Installation of formwork steel bars, S4. Installation of the device body, S5. Concrete pouring, S6. Hole cavity construction, S7. Filling with stress absorbing material to form a group of stress absorbing holes. The present invention constructs an active stress absorption system, which changes crack control from passive repair to active prevention. By providing a group of stress absorbing holes filled with stress absorbing material inside the dam body, the internal stress of the dam body is effectively absorbed, providing a key technical means for solving the problem of crack control during the construction and operation of concrete gravity dams.

Description

Technical Field

[0001] The present invention belongs to the technical field of gravity dams, and specifically relates to a stress absorption construction device and method for active prevention and control of cracks in gravity dams. Background Art

[0002] Gravity dams, as key structures in water conservancy projects, play a vital role in regulating water resources, preventing floods and reducing disasters, and ensuring water supply for agricultural production and residents. Dam cracks have long been a key research focus and challenge for scholars both domestically and internationally. Existing technologies primarily utilize medium- and low-heat cements. By optimizing concrete mix proportions, reducing the amount of cementitious materials, adjusting aggregate gradations, and applying shrinkage compensation, these technologies reduce concrete temperature rise and the risk of cracking. From a construction perspective, concrete is constructed in compartments and layers, with cooling water pipes embedded within the concrete to lower mixing water temperature and pre-cool the aggregates. This reduces heat in the concrete, minimizes the internal and external temperature difference, improves temperature distribution, and reduces thermal stress. Concrete curing methods, such as intelligent spraying and covering insulation, reduce internal and external temperature differences in concrete. Research and practice have shown that these technical measures have, to a certain extent, reduced temperature and shrinkage stresses in dam concrete, mitigating the risk of dam cracking.

[0003] However, internal stress within the dam structure is the root cause of concrete cracks. Therefore, eliminating this internal stress is crucial for resolving cracks during construction and operation of concrete gravity dams. Existing research methods, whether reducing concrete thermal stress or shrinkage stress, have struggled to fundamentally eliminate internal stress within the dam, and suffer from insufficient internal stress regulation.

[0004] Therefore, how to optimize the stress distribution inside the dam, reduce stress concentration, and develop a stress absorption construction device and method that can be integrated into the dam body, has strong interface bonding ability, and is feasible to construct, has become a key breakthrough direction for solving the problem of cracks in gravity dams. Summary of the Invention

[0005] Based on the problems existing in the background technology, the present invention proposes a stress absorption construction device and method for active prevention and control of gravity dam cracks.

[0006] In a first aspect, the present technical solution proposes a stress absorption construction device for active prevention and control of cracks in gravity dams, comprising a device body, the device body comprising a second tube body, the second tube body having a closed bottom end and an open top end; the second tube body having at least one array of holes formed on its wall, the array of holes comprising a plurality of spaced through holes arranged along the height direction of the second tube body;

[0007] A vertical strip is provided in the inner cavity of the second tube body, and a plurality of column heads that can be adapted and plugged into the through holes are provided on the strip. When the column head is squeezed by external force, the column head can move, and one end of the column head extends outward through the through hole.

[0008] Preferably, the strip is fixedly connected to the inside of the second tube body; the column head is slidably connected to the strip; a compression spring is sleeved on the column head, one end of the compression spring is connected to one end of the column head, and the other end is connected to the strip.

[0009] Preferably, the strip is slidably connected to the inner wall of the second tube body, and the column head is fixed on the strip.

[0010] Preferably, a compression spring is sleeved on the column head, and one end of the compression spring is fixed on the strip board.

[0011] Preferably, the device body further comprises a second airbag, a mounting space is formed between the plurality of strips, and the second airbag can be placed in the mounting space; the second airbag is provided with an inflatable / deflated valve.

[0012] Preferably, a sealing ring is provided on the hole wall of the through hole, and the column head can be connected to the sealing ring in a sealing and sliding manner.

[0013] Preferably, the column head is cylindrical, conical or polygonal.

[0014] Preferably, one end of the column head is connected to an end plate, and one end of the compression spring is connected to the end plate.

[0015] In a second aspect, this technical solution also proposes a stress absorption construction method for active prevention and control of gravity dam cracks, using the stress absorption construction device for active prevention and control of gravity dam cracks, including the following steps:

[0016] S1. Construction preparation: diversion, site leveling, and material preparation;

[0017] S2. Foundation treatment: dam foundation excavation, bedrock treatment and grouting;

[0018] S3. Install formwork reinforcement: erect formwork and tie reinforcement;

[0019] S4. Install the device: Position and install the device in the designed position;

[0020] S5. Concrete pouring: pouring in blocks and layers, temperature-controlled vibration, and curing;

[0021] S6. Cavity Construction: After the concrete has initially set, the pull-out device body forms a cavity with an uneven interface;

[0022] S7. Filling with stress absorbing material: After checking that the cavity meets the design requirements, fill the cavity with stress absorbing material. The stress absorbing material is integrated with the inner wall of the cavity, forming a mosaic structure at the boundary; after filling, a stress absorbing hole group is formed.

[0023] Preferably, the method for constructing the S6 mesocavity is:

[0024] During use, an uninflated second airbag is placed in the second tube body, and then the second airbag is inflated. The second airbag is inflated and bulges, squeezing the column head, compressing the compression spring, and one end of the column head extends out through the through hole. After concrete is poured, the column head exposed outside the second tube body is buried in the concrete.

[0025] After the concrete has initially set, the second airbag is deflated and the column head moves backward into the second tube body under the elastic force of the compression spring. After the column head withdraws, a recessed portion is formed in the concrete. Subsequently, the second airbag and the second tube body are pulled out to form a cavity with a hole array.

[0026] The above technical solution has the following advantages:

[0027] 1. The construction device designed by the present invention can realize one-time molding of mosaic interface cavities with a high pass rate; and the process is seamlessly integrated into the cast-in-place process, effectively shortening the construction period and reducing the overall cost. This construction device has a simple structure and is easy to operate, which can ensure the molding accuracy and efficiency of complex cavity structures. By using this construction device, a recessed portion is constructed on the inner wall of the cavity, so that the filled stress-absorbing material and the concrete form a mechanical mosaic interface, which improves the reliability of the bonding between the stress-absorbing material and the concrete interface, ensures efficient stress transmission and prevents debonding failure, and ensures collaborative work throughout the entire life cycle. The mosaic structure achieves interlocking resistance to interlayer slippage, and the crack expansion path is blocked, so that the stress absorption of the stress-absorbing material and the bearing function of ordinary concrete are more coordinated. Although it increases the complexity of construction, it significantly improves the crack control effect of the dam and is more adaptable to the complex stress of the dam.

[0028] 2. This method constructs an active stress absorption system, transforming crack control from passive repair to active prevention. By setting up a vertical cavity network inside the dam body and filling the cavity with low-modulus elastic-plastic stress-absorbing material to form a distributed stress-absorbing pore group, it effectively absorbs the internal stress of the dam body and reduces the peak stress of the dam body, providing a key technical means for solving the problem of crack control during the construction and operation of concrete gravity dams. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific implementation of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the specific implementation or the description of the prior art.

[0030] Figure 1This is a structural cross-sectional view of the device body in Example 1.

[0031] Figure 2 yes Figure 1 A top view of the device body before it is cut open.

[0032] Figure 3 This is an enlarged schematic diagram of the structure of area A.

[0033] Figure 4 It is a structural schematic diagram of the device body composed of the first tube body and the spring hose in Example 2.

[0034] Figure 5 This is a schematic structural diagram of the device body composed of the first airbag and the spring hose in Example 2.

[0035] Figure 6 It is a structural diagram of a spring hose.

[0036] Figure 7 It is a structural diagram of a group of stress-absorbing holes set in a gravity dam.

[0037] Figure 8 It is an enlarged cross-sectional view of a single cavity before filling with stress absorbing material.

[0038] Figure 9 Process flow chart of the construction method of the present invention.

[0039] Figure 10 This is a structural cross-sectional view of the device body in Example 3.

[0040] Figure 11 yes Figure 10 A magnified view of the structure in region F.

[0041] Figure 12 It is a structural diagram of the strip board in Example 3.

[0042] Figure 13 This is a top view of the guide bracket.

[0043] Description of reference numerals:

[0044] 1. Dam foundation; 2. Dam body; 3. Stress absorbing material; 4. Cavity; 5. Recessed portion; 6. First tube body; 7. Spring hose; 9. First airbag; 10. Second tube body; 11. Strip plate; 12. Through hole; 13. Column head; 14. Compression spring; 15. End plate; 16. Second airbag; 17. Sealing ring; 18. Guide bracket; 19. Strip groove; 20. Ring sleeve. DETAILED DESCRIPTION

[0045] The following embodiments of the technical solution of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and are therefore only examples and are not intended to limit the scope of protection of the present invention.

[0046] Example 1:

[0047] like Figure 1 - Figure 7 As shown, this embodiment proposes a stress absorption construction device for active prevention and control of cracks in gravity dams, including a device body, which includes a second tube body 10, the bottom end of the second tube body 10 is closed, and the top end is open; the second tube body 10 is provided with at least one group of hole arrays on the tube wall, and the hole array includes a plurality of spaced through holes 12 arranged along the height direction of the second tube body 10; the hole arrays are distributed circumferentially along the second tube body 10, and can be two groups, three groups or four groups or more groups; in this embodiment, two groups can be provided as an exemplary reference.

[0048] A vertical strip 11 is provided in the internal cavity of the second tube body 10, and a plurality of column heads 13 are provided on the strip head 11 and can be adapted to be plugged into the through holes 12; when the column heads 13 are squeezed by external force, the column heads 13 can move, and one end of the column heads 13 extends outward through the through holes 12.

[0049] Regarding the connection between the strip board 11 and the column head 13, the following structure can be adopted:

[0050] A vertical strip 11 is installed within the interior cavity of the second tube 10. Strip 11 is fixedly connected to the interior of the second tube 10, either by bonding or welding. Strip 11 is equipped with a number of studs 13 that fit into through-holes 12 and are slidably connected to the strip 11. Studs 13 are sleeved with compression springs 14, one end of which is connected to one end of the stud 13 and the other to the strip 11. When external force compresses one end of the stud 13, the stud 13 moves, and the other end of the stud 13 extends outward through through-holes 12. Initially, studs 13 are concealed within the second tube 10, creating a hidden design.

[0051] To facilitate the movement of the column head 13, the device body also includes a second airbag 16. The plurality of slats 11 define a mounting space within which the second airbag 16 can be placed. A valve for inflation and deflation is provided on the second airbag 16. During use, the inflated second airbag 16 expands, squeezing the column head 13 and extending it.

[0052] In this embodiment, in order to facilitate the squeezing of the column head 13 , one end of the column head 13 is connected to the end plate 15 , and one end of the compression spring 14 is connected to the end plate 15 .

[0053] The specific usage is as follows:

[0054] During use, the uninflated second airbag 16 is placed in the second tube body 10, and then the second airbag 16 is inflated. The second airbag 16 is inflated and bulged, squeezing the end plate 15. The end plate 15 compresses the compression spring 14, and the column head 13 extends out through the through hole 12. After pouring concrete, the column head 13 exposed outside the second tube body 10 is buried in the concrete; after the concrete is initially solidified, the second airbag 16 is deflated, and the second airbag 16 becomes deflated. The column head 13 moves backward into the second tube body 10 under the elastic force of the compression spring 14; after the column head 13 withdraws, a recessed portion 5 is formed in the concrete. Subsequently, the second airbag 16, the second tube body 10, etc. are pulled out to form a cavity 4 with a recessed portion 5 with a hole pattern.

[0055] In this embodiment, in order to prevent slurry from entering the second tube body 10, a sealing ring 17 is provided on the hole wall of the through hole 12, and the column head 13 can be sealingly and slidingly connected with the sealing ring 17, which can effectively achieve slurry isolation.

[0056] During the pouring and vibrating of gravity dam concrete, traditional non-sealed structures can easily cause cement slurry to seep into the second tube body 10 through the gap between through-hole 12 and column head 13, causing problems such as column head 13 jamming and compression spring 14 rusting and failure. Sealing ring 17, made of silicone rubber or fluororubber, completely blocks the infiltration of concrete slurry, ensuring that the column head 13's telescopic mechanism remains in a clean environment and achieving a high pass rate for hole formation.

[0057] The inner side of the sealing ring 17 is mirror polished and lubricated with a graphite coating, which effectively reduces the sliding friction of the column head 13. Even under slight viscosity before the initial setting of the concrete, rapid retraction can still be achieved through the elastic force of the compression spring 14, avoiding the risk of pipe jamming after the concrete hardens.

[0058] In this embodiment, the column head 13 is cylindrical, conical or polygonal.

[0059] like Figure 7 - Figure 9 As shown, this embodiment also proposes a stress absorption construction method for active prevention and control of gravity dam cracks, using the above-mentioned stress absorption construction device for active prevention and control of gravity dam cracks, including the following steps:

[0060] S1. Construction preparation: diversion, site leveling, and material preparation;

[0061] 1-1. Diversion Project: Select a diversion scheme (phased cofferdam / full cofferdam) based on hydrological conditions, and complete the construction of upstream and downstream cofferdams, diversion tunnels / open channels;

[0062] 1-2. Site preparation: Level the dam foundation 1 and the working area, build a mixing station, transportation channels, water and power supply systems, and complete raw material inspection and concrete mix design.

[0063] S2. Foundation treatment: excavation of dam foundation 1, bedrock treatment and grouting;

[0064] 2-1. Excavation of dam foundation 1: Use blasting / mechanical excavation to remove the overburden and weathered rock to the designed foundation surface, and use anchor spraying to support the slope to ensure stability;

[0065] 2-2. Bedrock treatment and grouting: After excavation to fresh bedrock and cleaning and acceptance, 5-8 meter deep holes are drilled in the dam foundation for consolidation grouting to enhance the integrity; deep holes are drilled at the heel of the dam for curtain grouting to form an anti-seepage barrier.

[0066] S3. Install formwork reinforcement: erect formwork and tie reinforcement;

[0067] 3-1. Set up the steel formwork, calibrate the verticality, and seal the joints to prevent leakage; tie the steel bars according to the drawing, control the spacing and thickness of the protective layer, and ensure the joints are compliant.

[0068] 3-2. Layout of cooling water system: Lay cooling water pipes on the inner side of the formwork and between the steel skeleton and fix them with steel brackets; connect the inlet and outlet of the cooling water pipes to the external water main of dam body 2, install temperature control valves and flow sensors, and bury temperature monitoring elements simultaneously.

[0069] S4. Install the device body: Position and install the device body at the designed position; during construction, mark the hole position according to the axis and position and install the device body; after installation, place the uninflated second airbag 16 into the installation space surrounded by the strip board 11, and then inflate the second airbag 16. The second airbag 16 inflates and bulges, squeezing the end plate 15. The end plate 15 compresses the compression spring 14, and the column head 13 extends through the through hole 12.

[0070] S5. Concrete pouring: pouring in blocks and layers, temperature-controlled vibration, and curing;

[0071] 5-1. Layering and Blocking: The dam body 2 is usually divided along the axis and layered vertically, using the through-casting or columnar casting method;

[0072] 5-2. Transport to warehouse: Use tower crane bucket or cable crane to transport concrete, the free fall height into the warehouse is ≤2m, and the temperature of the warehouse is controlled;

[0073] 5-3. Vibration curing: The inserted vibrator should be ≥30cm away from the hole-making device, and vibrate until the slurry is overflowing and free of bubbles; after initial setting, cover with heat-insulating and moisture-retaining materials, and the curing period should be ≥28 days.

[0074] After pouring the concrete, the column head 13 exposed outside the second tube body 10 is buried in the concrete.

[0075] S6. Construction of cavity 4: After the concrete has initially set, the pull-out device body is pulled out to form a cavity 4 with an uneven interface.

[0076] When to Pull Out: After the concrete has initially set, use the pulling equipment to lift the concrete. Monitor the resistance during the process and immediately pause and make adjustments if any stalling is detected. Pulling out after initial setting ensures that the shape of the cavity 4 is essentially stable—that is, the concrete has sufficient strength to support the hole walls—while also allowing for relatively easy extraction of the device to form the recessed portion 5 before the concrete's plasticity has completely disappeared, thus avoiding damage to the hardened concrete.

[0077] Tube extraction method: After the concrete has initially set, the second airbag 16 is deflated, and the second airbag 16 becomes deflated. The column head 13 moves backward into the second tube body 10 under the elastic force of the compression spring 14; after the column head 13 is withdrawn, a recessed portion 5 is formed in the concrete. Subsequently, the second airbag 16, the second tube body 10, etc. are pulled out to form a cavity 4 with a hole-shaped recessed portion 5.

[0078] S7. Filling with stress-absorbing material 3: After checking that the cavity 4 meets the design requirements, fill the cavity 4 with stress-absorbing material 3. The stress-absorbing material 3 is integrated with the inner wall of the cavity 4, forming a mosaic structure at the boundary; after filling, a stress-absorbing hole group is formed.

[0079] In this embodiment, the stress absorbing material 3 includes but is not limited to rubber concrete, rubber asphalt mortar, acrylic concrete, acrylic rubber concrete, acrylic mortar, acrylic rubber mortar, epoxy asphalt mortar, fiber reinforced rubber concrete, and fiber reinforced acrylic mortar.

[0080] The stress-absorbing material 3 in the above two embodiments is a type of engineering material with high elasticity, low stiffness, and good energy absorption capacity. It has the characteristics of low modulus, high ductility, and good adhesion. Through its own deformation or internal damping, it absorbs and dissipates the stress generated by the dam under temperature changes, shrinkage, and load, inhibits the initiation and expansion of cracks, and improves the durability of the structure.

[0081] The core functions of stress absorbing material 3:

[0082] First, stress buffering: absorbing energy (such as temperature stress and uneven foundation settlement stress) through elastic deformation; second, crack control: reducing interface stress concentration and delaying the crack expansion path; third, collaborative work: forming a composite system with ordinary concrete to improve the overall deformation coordination.

[0083] In summary: The present invention constructs an active stress absorption system, introduces a group of stress absorption holes into the main structure of the gravity dam, and serves as an active, distributed stress absorption unit, rather than passive bearing or post-processing, thereby changing crack control from passive repair to active prevention, and realizing the active reduction of the stress peak inside the dam body 2.

[0084] The present invention employs a chimeric structure, not simply filling the holes. Instead, the concave and convex shapes of the inner walls of the cavities 4 significantly increase the contact area and interfacial fit between the stress-absorbing material 3 and the concrete of the dam body 2. This mechanical interlocking effect greatly enhances their ability to work together, preventing debonding and ensuring effective stress transfer to the stress-absorbing material 3. This interlocking effect resists interlayer slippage, improves interfacial bond strength and deformation coordination, and is more adaptable to the complex stresses of the dam.

[0085] Example 2:

[0086] like Figure 4 - Figure 6 As shown, in this embodiment, unlike in Example 1, the device body can be replaced with the following structure: the device body includes a support body, at least the bottom end of which is closed; a spring hose 7 is spirally wound around the outer wall of the support body, the bottom end of the spring hose 7 being fixedly connected to the outer wall of the bottom end of the support body; the top end of the spring hose 7 is detachably connected to the outer wall of the top end of the support body; the head and tail ends of the spring hose 7 are sealed, and the interior is filled with a gas or liquid medium. The liquid medium filled can be water or hydraulic oil.

[0087] In this embodiment, the supporting body is the first tube 6 or the first airbag 9; the first tube 6 is a PVC tube or a steel tube.

[0088] When the supporting body is the first airbag 9 , the top of the first airbag 9 is also a closed end, and the end is provided with an air nozzle capable of inflating and deflation.

[0089] A valve is installed at the top of the spring hose 7 to control the filling and discharging of the hose. This is because the spring hose 7 has a certain degree of elasticity. When inflated, the internal air pressure causes the hose to expand, thereby increasing its radial rigidity. This allows the spring hose 7 to withstand external pressure during concrete pouring. The stiffness of the hose after being filled with gas or liquid can withstand this pressure and maintain its spiral shape. This provides greater stability than an unfilled spring hose 7, especially when the concrete is highly fluid. This prevents the hose from being flattened or deformed, which could result in unclear spiral groove formation.

[0090] Furthermore, when the spring hose 7 is not filled with a medium, a gap easily forms between the spring hose 7 and the first airbag 9, preventing a tight fit. Concrete can seep into the gap, making extraction difficult and affecting the surface quality of the channel. However, when the spring hose 7 is expanded, it adheres tightly to the surface of the first airbag 9, eliminating the gap and forming a rigid spiral support layer. During concrete pouring, the internal pressure counteracts the external pressure, preventing radial contraction or spiral deformation of the hose due to pressure.

[0091] In this embodiment, the stiffness of the spring hose 7 is adjusted by filling a medium, thereby solving the contradiction of the traditional template being "flexible and easy to deform, but rigid and difficult to disassemble", significantly improving the molding quality and construction efficiency of the spiral groove, and being simple and practical.

[0092] The second method for constructing cavity 4 in S6 is:

[0093] ① When the supporting body is the first tube 6, the method is as follows:

[0094] Disassemble and separate the top end of the spring hose 7 from the top end of the first tube body 6;

[0095] When the first tube body 6 is lifted, the first tube body 6 can slide along the cavity and can also slide relative to the spring hose 7. Since the bottom end of the spring hose 7 is fixedly connected to the bottom end of the first tube body 6, as the first tube body 6 moves upward, the first tube body 6 pulls the spring hose 7 to move, thereby pulling the spring hose 7 out of the concrete.

[0096] As the first tube body 6 continues to move upward, the spring hose 7 is continuously separated from the concrete, and a spiral groove is formed after the separation; when the first tube body 6 is completely pulled out, the cavity 4 with the spiral groove is formed.

[0097] ② When the supporting body is the first airbag 9, the method is as follows:

[0098] Deflate the first airbag 9;

[0099] After the first airbag 9 is deflated, it no longer supports the spring hose 7 and the first airbag 9 is directly pulled upward. The first airbag 9 and the spring hose 7 are pulled out, and the cavity 4 with the spiral groove is formed.

[0100] The device body proposed in this embodiment adopts the structure of PVC tube / steel tube / first airbag 9+spring hose 7, which has a simple structure. The materials used (PVC tube, steel tube, spring hose 7, first airbag 9) are all conventional engineering materials, and there are no technical obstacles in manufacturing; the construction process is simple and easy to implement, does not require special equipment, and is easy for workers to operate.

[0101] Application results:

[0102] First, construction convenience: after the first airbag 9 is deflated, the spring hose 7 can be quickly pulled out without mechanical twisting or complicated disassembly; second, structural adaptability: the shape and size of the spiral groove can be flexibly controlled by adjusting the winding density and pitch of the spring hose 7; third, cost-effectiveness: the first airbag 9 and the spring hose 7 can be reused, significantly reducing template loss.

[0103] Example 3:

[0104] Different from Example 1, the device body can also be replaced with the following structure:

[0105] like Figure 10 - Figure 13 The device body includes a second tube body 10, the bottom end of the second tube body 10 is closed and the top end is open; the second tube body 10 is provided with at least one group of hole arrays on the tube wall, and the hole array includes a plurality of spaced through holes 12 arranged along the height direction of the second tube body 10; the hole arrays are distributed circumferentially along the second tube body 10, and can be two groups, three groups, four groups or more groups; in this embodiment, two groups can be provided as an example.

[0106] In this embodiment, the strip 11 is slidably connected to the inner wall of the second tube 10, and the stud 13 is fixed to the strip 11. A compression spring 14 is also sleeved on the stud 13. One end of the compression spring 14 is fixed to the strip 11; the other end is free. When the strip 11 is squeezed, the compression spring 14 is compressed and presses against the inner wall of the second tube 10. Driven by the strip 11, the stud 13 passes through the through hole 12.

[0107] In order to facilitate the movement of the strip plate 11 , in this embodiment, the inner wall of the second tube body 10 has a guide bracket 18 , and the guide bracket 18 is provided with a strip groove 19 , and the strip plate 11 can slide along the strip groove 19 .

[0108] In some embodiments, both ends of the strip plate 11 have protrusions, which can be inserted into the strip groove 19 and slide along the strip groove 19 .

[0109] To facilitate guidance, guide brackets 18 may be provided on both the upper and bottom portions of the second tube body 10 .

[0110] In some embodiments, a ring sleeve 20 may be sleeved on the column head 13 , and the ring sleeve 20 can slide left and right along the column head 13 ; one end of the compression spring 14 is fixedly connected to the strip board 11 , and the other end is fixedly connected to the ring sleeve 20 .

[0111] The working principle of the device body in this embodiment is as follows:

[0112] During use, the uninflated second airbag 16 is placed in the installation space surrounded by the strips 11. The second airbag 16 is then inflated. The second airbag 16 inflates and swells, squeezing the strips 11. The strips 11 drive the column head 13 to move. The compression spring 14 is supported against the inner wall of the second tube body 10 and compressed. The other end of the column head 13 extends out through the through hole 12. After concrete is poured, the column head 13 exposed outside the second tube body 10 is buried in the concrete.

[0113] After the concrete has initially set, the second airbag 16 is deflated and the second airbag 16 becomes deflated. The column head 13 moves backward into the second tube body 10 under the elastic force of the compression spring 14. After the column head 13 withdraws, a recessed portion 5 is formed in the concrete. Subsequently, the second airbag 16 and the second tube body 10 are pulled out to form a cavity 4 with a hole array.

[0114] Through the two embodiments of Example 1 and Example 3, the design of the second airbag 16 driving the column head 13 to expand and contract and the compression spring 14 to return to its original position is adopted to achieve the formation of the regular hole-shaped recessed portion 5 in the concrete member. The technical advantages thereof include:

[0115] Structural aspects:

[0116] 1. Hidden stud 13 design avoids interference with concrete pouring: Initially, stud 13 is hidden within second tube 10, creating a smooth surface during concrete pouring. This prevents stud 13 from prematurely contacting the concrete, causing jamming or deformation, and ensures dense concrete filling. After the second airbag 16 is inflated, stud 13 synchronously and stably extends through through-hole 12, forming a regular raised structure. After the concrete initially sets, stud 13 retracts, leaving a precisely defined recess 5 with a consistent diameter and depth.

[0117] 2. The hole array can be arranged in multiple groups (e.g., 2-4 groups) along the circumference, and the column heads 13 are spaced apart along the height direction. By adjusting the number of hole array groups, the spacing between the column heads 13, and the extension length, linearly arranged holes, annular hole groups, and customized hole shapes (e.g., honeycomb and tooth-like structures) can be formed to meet the functional opening requirements of different gravity dams.

[0118] 3. After the second airbag 16 is inflated, it can evenly squeeze all the studs 13 through air pressure, so that multiple studs 13 can be extended synchronously without manual adjustment one by one, which greatly shortens the assembly and positioning time of the hole-making device. It is especially suitable for large-area, multi-hole drilling scenarios.

[0119] 4. After the initial setting of the concrete, the second airbag 16 is deflated and the column head 13 is quickly retracted into the tube body under the elastic force of the compression spring 14, preventing the column head 13 from being retained in the concrete to form "barbs", reducing the friction resistance and adhesion during tube extraction, significantly improving the demoulding efficiency, and avoiding concrete damage or hole wall cracking caused by forced tube extraction.

[0120] 5. The strips 11, column heads 13, second airbags 16 and other components can be independently disassembled and replaced. The second tube body 10 is made of wear-resistant materials (such as PVC, metal or high-strength HDPE or steel-plastic composite pipe), and the second airbag 16 is made of anti-aging rubber. The entire device can be reused multiple times, reducing construction costs.

[0121] Process:

[0122] 1. Suitable for gravity dam construction, where vibrations are performed at high frequencies, the device utilizes a dual-position limiter system, a compression spring 14 and a secondary airbag 16. After inflation, the column head 13 extends and locks, with the compression spring 14 providing rigid support to resist displacement caused by the vibration force. After deflation, the spring force ensures the column head 13 quickly returns to its original position, preventing loosening of the column head 13 and concrete infiltration during vibration, ensuring a high rate of complete channel formation. 2. The device can be integrated into conventional formwork systems, eliminating the need for additional large-scale equipment. By adjusting the pressure of the secondary airbag 16 and the parameters of the column head 13, it is compatible with existing processes, offering a low barrier to entry and broad applicability.

[0123] The above description is only a preferred embodiment of the present invention and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A stress absorption construction device for active prevention and control of cracks in gravity dams, comprising a device body, characterized in that: The device body comprises a second tube body (10), the bottom end of the second tube body (10) is closed and the top end is open; the second tube body (10) is provided with at least one group of hole arrays on the tube wall, the hole array comprising a plurality of spaced through holes (12) arranged along the height direction of the second tube body (10); A vertical strip (11) is provided in the inner cavity of the second tube body (10), and a plurality of column heads (13) are provided on the strip head (11) and can be adapted to be plugged into the through hole (12); when the column head (13) is squeezed by an external force, the column head (13) can move, and one end of the column head (13) extends outward through the through hole (12); The strip plate (11) is fixedly connected to the interior of the second tube body (10); the column head (13) is slidably connected to the strip plate (11); a compression spring (14) is sleeved on the column head (13), one end of the compression spring (14) is connected to one end of the column head (13), and the other end is connected to the strip plate (11); The device body also includes a second airbag (16), and a mounting space is formed between the plurality of strips (11), and the second airbag (16) can be placed in the mounting space; the second airbag (16) is provided with an inflatable / deflated valve.

2. A stress absorption construction device for active prevention and control of gravity dam cracks according to claim 1, characterized in that: A sealing ring (17) is provided on the hole wall of the through hole (12), and the column head (13) can be connected to the sealing ring (17) in a sealing and sliding manner.

3. A stress absorption construction device for active prevention and control of gravity dam cracks according to claim 1, characterized in that: The column head (13) is cylindrical, conical or polygonal.

4. A stress absorption construction device for active prevention and control of gravity dam cracks according to claim 1, characterized in that: One end of the column head (13) is connected to an end plate (15), and one end of the compression spring (14) is connected to the end plate (15).

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