A device for preventing concrete cracking in the sidewalls of underground structures

Abstract

This invention discloses a concrete crack prevention device for underground structure sidewalls in the field of concrete pouring technology. The device includes a mounting base and unit probes. Each unit probe includes a connecting sleeve, inside which a drive shaft is rotatably mounted. A drive motor is fixedly mounted at the top of the connecting sleeve, and helical blades are fixedly mounted on the bottom surface of the drive shaft. An expansion shroud is fixedly mounted on the surface of the connecting sleeve. During concrete pouring, a suitable number of unit probes are inserted into the center of the concrete sidewall. Cooling medium is injected into the expansion shroud to cool the center of the concrete, neutralizing the heat of hydration at the center, delaying the hydration peak, and reducing the temperature difference between the inner and outer surfaces of the concrete wall. This helps reduce temperature stress concentration in the concrete and lowers the risk of temperature cracking. As the pouring process continues, the unit probes can be pulled out, eliminating the need for pre-embedded water pipes and achieving the effect of preventing concrete cracking.

Description

Technical Field

[0001] This invention relates to the field of concrete pouring technology, and more particularly to a device for preventing concrete cracking in the sidewalls of underground structures. Background Technology

[0002] Cracks in underground concrete walls are a common phenomenon. While some small cracks may not pose a threat to the normal use of a building structure, if these structures with small cracks are subjected to large loads or under the combined effects of external physical and chemical factors, the steel reinforcement inside the concrete is prone to corrosion. As the corrosion progresses, the strength of the reinforced concrete material and the stiffness of the components will decrease, thereby affecting the normal use of the building.

[0003] In the prior art, patent document CN222184188U discloses a pre-embedded cooling device for preventing cracking in thick-walled concrete, comprising: a water pipe, which is pre-embedded in a spiral shape within the concrete wall, with both ends of the water pipe located on the outer side of the concrete wall; support components are provided on both the left and right sides of the lower end of the water pipe, and hoisting components are provided on both the left and right sides of the upper end of the water pipe; cooling components are detachably installed on the outer wall of the water pipe, including an arc-shaped heat-conducting plate one and an arc-shaped heat-conducting plate two. By pre-embedding the water pipe in the concrete, the upper end of the water pipe is connected to an external circulating water tank through a water pump, and the lower end of the water pipe is connected to an external circulating water tank through a connecting pipe. When the water pump is started, water is kept flowing in the water pipe. The cooling components, support components, and hoisting components exchange heat with the inside of the concrete and the cold water in the water pipe, thereby removing heat from the inside of the concrete and cooling the inside of the concrete.

[0004] In practical use, water pipes embedded in the concrete are used to cool the interior and prevent the concrete wall from cracking. However, the embedded water pipes cannot be reused, which is costly. Moreover, the embedded water pipes in the wall often do not meet the design requirements. As a result, the underground sidewall is a large-volume concrete pouring project with a significant hydration heat effect. The thicker the concrete wall, the higher the hydration heat and temperature stress will be, and the more likely it is to crack. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies, such as the significant impact of hydration heat and temperature stress on the pouring of underground sidewalls, which easily leads to cracks. Therefore, this invention proposes a device to prevent concrete cracking in underground structural sidewalls.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a concrete crack prevention device for the sidewall of an underground structure, comprising a mounting base and a unit probe, wherein the unit probe comprises a connecting sleeve, a drive shaft is rotatably mounted inside the connecting sleeve, a drive motor is fixedly mounted at the top end of the connecting sleeve, the top end of the drive shaft is fixedly connected to the rotating end of the drive motor, the bottom end of the drive shaft extends to the outside of the connecting sleeve, and a helical blade is fixedly mounted on the bottom surface of the drive shaft.

[0007] An expansion sleeve is fixedly installed on the surface of the connecting sleeve. The interior of the expansion sleeve is a closed cavity. A connecting pipe is provided on the surface of the expansion sleeve, and the connecting pipe communicates with the inner cavity of the expansion sleeve.

[0008] The mounting base is fixedly installed on the upper side of the template for pouring the underground structure sidewall. The connecting sleeve is slidably inserted into the mounting base. The expansion cover is placed in the template pouring cavity. During the concrete pouring process, the expansion cover is embedded in the concrete. Cooling medium is injected into the expansion cover to cool the center of the concrete, neutralize the heat of hydration in the center of the concrete, reduce the temperature difference between the inside and outside of the concrete wall, and help reduce the temperature stress concentration of the concrete, thereby achieving the effect of preventing concrete cracking.

[0009] Preferably, the expansion shroud has a cylindrical hollow structure with tapered ends. The expansion shroud is made of aluminum plate, and the connecting pipe includes an input pipe and an output pipe. Both the input pipe and the output pipe are fixedly installed on the surface of the connecting sleeve. The bottom end of the input pipe extends to the lower part of the inner cavity of the expansion shroud, and the lower end of the input pipe extends to the upper part of the inner cavity of the expansion shroud. Both the input pipe and the output pipe are fixedly installed with pipe joints. Cooling medium is circulated into the expansion shroud to improve heat exchange efficiency.

[0010] Concrete is poured into the casting cavity of the template, and the concrete is covered with an expansion cover. When the drive motor starts, the spiral blades drive the concrete to flow through the transmission shaft, so that the concrete is evenly distributed in the dead corners and corners of the steel cage, reducing the occurrence of grout shortage, small pits or exposed reinforcement on the concrete surface.

[0011] Preferably, a guide sleeve is fixedly installed at the end of the mounting base. The guide sleeve is arranged vertically, and the inner cavity of the guide sleeve has three through holes. The connecting sleeve, the input pipe and the output pipe are slidably inserted into each through hole. A vibrator is fixedly installed on the upper surface of the connecting sleeve.

[0012] Concrete is poured into the casting cavity of the template, and the concrete covers the expansion cover. When the drive motor and vibrator are both started, the unit probe moves upward under the reaction force of the concrete pushed by the spiral blade and the vibration of the concrete around the expansion cover driven by the vibrator. As the depth of concrete pouring in the template increases, the unit probe automatically floats up, which meets the needs of concrete layering and vibration construction, and solves the quality problems caused by over-vibration or under-vibration, making concrete pouring more convenient.

[0013] Preferably, a reinforcing cage is installed inside the casting cavity of the template. An insertion opening is reserved inside the reinforcing cage. The unit probe is inserted into the insertion opening inside the reinforcing cage. A guide gap is reserved on the surface of the expansion cover and the inner wall of the template. The guide gap is relatively narrow. When the concrete flows through the guide gap, the concrete can fully contact the surface of the expansion cover to exchange heat and achieve a better cooling effect.

[0014] Preferably, there are multiple mounting seats and unit probes. An installation beam is fixedly installed on the upper side of the template. Multiple mounting seats are fixedly installed on the installation beam by bolts. Each unit probe is arranged in parallel and slidably connected to each mounting seat. The number and position of the unit probes can be adjusted as needed. After the concrete is poured, the unit probes can be pulled out and reused.

[0015] The present invention has the following beneficial effects:

[0016] 1. The concrete crack prevention device proposed in this invention involves inserting a reasonable number of unit probes into the center of the concrete sidewall during the concrete pouring process. Cooling medium is injected into the expansion hood to cool the center of the concrete, neutralize the heat of hydration in the center of the concrete, delay the appearance of the hydration peak, reduce the temperature difference between the inside and outside of the concrete wall, which helps to reduce the concentration of temperature stress in the concrete and reduce the risk of temperature cracking. As the pouring work progresses, the unit probes can be pulled out, achieving the effect of preventing concrete cracking without the need for pre-embedded water pipes.

[0017] 2. The concrete crack prevention device proposed in this invention is equipped with a vibrator and a spiral blade on each unit probe. When the vibrator operates, it vibrates the unit probe, expelling air bubbles from the concrete and compacting the concrete. At the same time, it loosens the concrete around the unit probe, reducing the resistance of the concrete to the unit probe. In conjunction with the rotation of the spiral blade, it provides the upward force for the unit probe. As the depth of concrete pouring in the formwork increases, the unit probe automatically floats up, meeting the usage requirements of concrete layering and vibration construction.

[0018] 3. The concrete crack prevention device proposed in this invention has a spiral blade at the bottom of the unit probe. The process of the drive motor driving the spiral blade to rotate pushes the concrete to convect in the formwork pouring cavity, so that the concrete is evenly distributed in the dead corners and corners of the reinforcement cage, reducing the phenomenon of missing mortar, small pits or exposed reinforcement on the concrete surface. This design makes up for the drawbacks of vibration compaction. Because the vibration time, position and frequency of concrete are largely determined by the operator's experience, there are drawbacks of over-vibration or under-vibration. Over-vibration will cause the coarse aggregate in the concrete to settle and the coarse aggregate to separate from the mortar. Insufficient vibration time may not be able to make the concrete reach the required density, which will increase the risk of cracking.

[0019] 4. The concrete crack prevention device proposed in this invention uses an expansion hood on the surface of the unit probe. As the unit probe floats, concrete mortar flows into the lower side of the expansion hood. At the same time, the rotating spiral blades stir the concrete under the expansion hood, so that the coarse aggregate separated by vibration is mixed with the mortar again, ensuring sufficient vibration, eliminating defects such as insufficient mortar, small pits or exposed reinforcement in the concrete, and eliminating concerns about under-vibration. It solves the quality problem of easy cracking caused by over-vibration or under-vibration, making concrete pouring more convenient. Attached Figure Description

[0020] Figure 1 This is a three-dimensional structural diagram of the concrete crack prevention device proposed in this invention;

[0021] Figure 2 for Figure 1 Enlarged schematic diagram of the structure at point A in the diagram;

[0022] Figure 3 This is a schematic diagram of the front section of the anti-concrete cracking device proposed in this invention;

[0023] Figure 4 This is a side sectional view of the anti-concrete cracking device proposed in this invention.

[0024] Figure 5 This is a partial side section diagram of the anti-concrete cracking device proposed in this invention. Figure 1 ;

[0025] Figure 6 This is a partial side section diagram of the anti-concrete cracking device proposed in this invention. Figure 2 .

[0026] In the diagram: 1 Mounting base, 2 Connecting sleeve, 3 Drive shaft, 4 Drive motor, 5 Spiral blade, 6 Expansion cover, 7 Template, 8 Vibrator, 9 Input pipe, 10 Output pipe, 11 Pipe joint, 12 Guide sleeve, 13 Reinforcing cage, 14 Flow guide gap, 15 Mounting beam. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0028] In the description of this invention, it should 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 this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] Reference Figures 1-6 A device for preventing concrete cracking in the sidewall of an underground structure includes a mounting base 1 and a unit probe. The unit probe includes a connecting sleeve 2. A drive shaft 3 is rotatably mounted inside the connecting sleeve 2. A drive motor 4 is fixedly mounted at the top end of the connecting sleeve 2. The top end of the drive shaft 3 is fixedly connected to the rotating end of the drive motor 4. The bottom end of the drive shaft 3 extends to connect to the outside of the sleeve 2, and a spiral blade 5 is fixedly mounted on the bottom surface of the drive shaft 3.

[0030] like Figure 4 As shown, a vibrating rod 8 is fixedly installed on the upper surface of the connecting sleeve 2.

[0031] An expansion cover 6 is fixedly installed on the surface of the connecting sleeve 2. The interior of the expansion cover 6 is a closed cavity. A connecting pipe is provided on the surface of the expansion cover 6, and the connecting pipe communicates with the inner cavity of the expansion cover 6.

[0032] Specifically, the expansion cover 6 has a cylindrical hollow structure, and both the upper and lower ends of the expansion cover 6 are conical. The expansion cover 6 is made of aluminum plate. The connecting pipes include an input pipe 9 and an output pipe 10. Both the input pipe 9 and the output pipe 10 are fixedly installed on the surface of the connecting sleeve 2. The bottom end of the input pipe 9 extends to the lower part of the inner cavity of the expansion cover 6, and the lower end of the input pipe 9 extends to the upper part of the inner cavity of the expansion cover 6. Both the upper ends of the input pipe 9 and the output pipe 10 are fixedly installed with pipe joints 11.

[0033] Among them, a guide sleeve 12 is fixedly installed at the end of the mounting base 1. The guide sleeve 12 is arranged vertically, and the inner cavity of the guide sleeve 12 has three through holes. The connecting sleeve 2, the input pipe 9 and the output pipe 10 are slidably inserted into each through hole respectively.

[0034] Mounting base 1 is fixedly installed on the upper side of the template 7 for pouring the underground structure side wall. Connecting sleeve 2 is slidably inserted into the guide sleeve 12 on mounting base 1. Expansion cover 6 is placed in the pouring cavity of template 7.

[0035] A reinforcing cage 13 is installed inside the pouring cavity of template 7. An insertion opening is pre-reserved inside the reinforcing cage 13. A unit probe is inserted into the insertion opening inside the reinforcing cage 13. A guide gap 14 is pre-reserved between the surface of the expansion cover 6 and the inner wall of template 7. Figure 4 As shown.

[0036] In this embodiment, as Figure 1 , Figure 2 As shown, there are multiple mounting bases 1 and multiple unit probes. An installation beam 15 is fixedly installed on the upper side of the template 7. Multiple mounting bases 1 are fixedly installed on the installation beam 15 by bolts. Each unit probe is arranged in parallel and is slidably connected to each mounting base 1. The number and position of the unit probes can be adjusted as needed. After the concrete is poured, the unit probes can be pulled out and reused.

[0037] During the pouring of the underground structure sidewall, concrete is poured in from the top of the formwork 7 and flows downward through the guide gap 14 until the expansion shroud 6 is embedded in the concrete. At the same time, the pipe joint 11 is connected to the cooling system through a hose, and the cooling medium is injected into the expansion shroud 6 through the input pipe 9. The cooling medium absorbs the heat of the concrete outside the expansion shroud 6 and is then discharged through the output pipe 10.

[0038] It should be noted that cooling water can be used as the cooling medium, and the cooling system refers to the circulating water pump. When construction is carried out in hot summer weather, the cooling requirements are higher, and Freon refrigerant can be used as the cooling medium, and the cooling system refers to the compressor. In addition, the diameter of the expansion shroud 6 is determined by the size of the pouring cavity of the template 7. When the thickness of the poured wall is large, a larger diameter expansion shroud 6 should be selected, and the size of the guide gap 14 should be large enough for the concrete to pass through. The guide gap 14 is relatively narrow. When the concrete flows through the guide gap 14, it can fully contact the surface of the expansion shroud 6 to exchange heat and achieve a better cooling effect.

[0039] The concrete crack prevention device proposed in this invention involves inserting a reasonable number of unit probes into the center of the concrete sidewall during the concrete pouring process. Cooling medium is injected into the expansion shroud 6 to cool the center of the concrete, neutralize the heat of hydration in the center of the concrete, delay the appearance of the hydration peak, reduce the temperature difference between the inside and outside of the concrete wall, which helps to reduce the concentration of temperature stress in the concrete and reduce the risk of temperature cracking. As the pouring work progresses, the unit probes can be pulled out, achieving the effect of preventing concrete cracking without the need for pre-embedded water pipes.

[0040] It is important to note that there are many factors that can cause concrete structures to crack, such as temperature changes, moisture changes, load effects, construction quality, and material quality. Different design requirements and usage scenarios require different methods to address concrete cracking. This invention takes the large-volume concrete pouring of underground structure sidewalls as an example, where the pouring temperature and vibration construction have an impact, and proposes a concrete cracking prevention device.

[0041] During the concrete pouring process, a layered pouring method is used, such as... Figure 3 or Figure 6 As shown, concrete is poured into the pouring cavity of template 7. The first pour of concrete covers the expansion cover 6. The unit probe has a large volume at the position of the expansion cover 6. Under the buoyancy F1 of the concrete mortar and the resistance of the concrete to the expansion cover 6, the depth of the unit probe inserted into the concrete is normally fixed. When the drive motor 4 starts, the spiral blades 5 drive the concrete to flow through the transmission shaft 3, causing the concrete around the spiral blades 5 to form convection, such as... Figure 3 and Figure 6 As shown by the dashed arrow around the spiral blade 5, it should be noted that the weight G of the unit probe can be adjusted by increasing or decreasing the amount of water injected into the expansion shroud 6.

[0042] A spiral blade 5 is installed at the bottom of the unit probe. During the process of the drive motor 4 driving the spiral blade 5 to rotate, the spiral blade 5 pushes the concrete to convect in the pouring cavity of the formwork 7, so that the concrete is evenly distributed in the dead corners and corners of the steel cage 13, reducing the phenomenon of missing mortar, small pits or exposed reinforcement on the concrete surface. This design makes up for the drawbacks of vibration compaction. Because the vibration time, position and frequency of concrete vibration are largely determined by the operator's experience, there are drawbacks of over-vibration or under-vibration. Over-vibration will cause the coarse aggregate in the concrete to sink and the coarse aggregate to separate from the mortar. Insufficient vibration time may not be able to make the concrete reach the required density, which will increase the risk of cracking.

[0043] like Figure 5 , Figure 6 As shown, during the second concrete pouring process in the pouring cavity of template 7, drive motor 4 and vibrator 8 start simultaneously. Under the reaction force F2 of the concrete pushed by spiral blade 5 and the vibration of the concrete around expansion cover 6 driven by vibrator 8, the unit probe moves upward. Expansion cover 6 enters the second concrete layer in the direction of F3 and cools the upper concrete layer. It should be noted that the concrete around spiral blade 5 is flowing, and the force of F2 alone cannot lift the unit probe. However, at this time, vibrator 8 starts, and vibration loosens the concrete around the unit probe, reducing the resistance of the concrete to the unit probe, which allows the unit probe to float slowly.

[0044] Each unit probe is equipped with a vibrating rod 8 and a spiral blade 5. When the vibrating rod 8 is in operation, it vibrates the unit probe, expelling air bubbles from the concrete and compacting the concrete. At the same time, it loosens the concrete around the unit probe, reducing the resistance of the concrete to the unit probe. In conjunction with the rotation of the spiral blade 5, it provides the upward force for the unit probe. As the depth of concrete pouring in the formwork 7 increases, the unit probe automatically floats up, meeting the needs of concrete layering and vibration construction.

[0045] The concrete crack prevention device proposed in this invention uses an expansion cover 6 on the surface of a unit probe. As the unit probe floats upward, concrete mortar flows into the lower side of the expansion cover 6. At the same time, the rotating spiral blades 5 stir the concrete on the lower side of the expansion cover 6, so that the coarse aggregate separated by vibration is mixed with the mortar again, ensuring sufficient vibration, eliminating defects such as insufficient mortar, small pits or exposed reinforcement in the concrete, and eliminating concerns about under-vibration. It solves the quality problem of easy cracking caused by over-vibration or under-vibration, making concrete pouring more convenient.

[0046] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A device for preventing concrete cracking in the sidewall of an underground structure, comprising a mounting base (1) and a unit probe, characterized in that: The unit probe includes a connecting sleeve (2), a drive shaft (3) is rotatably installed inside the connecting sleeve (2), a drive motor (4) is fixedly installed at the top end of the connecting sleeve (2), the top end of the drive shaft (3) is fixedly connected to the rotating end of the drive motor (4), the bottom end of the drive shaft (3) extends to the outside of the connecting sleeve (2), and a spiral blade (5) is fixedly installed on the bottom surface of the drive shaft (3). An expansion cover (6) is fixedly installed on the surface of the connecting sleeve (2). The inside of the expansion cover (6) is a closed cavity. A connecting pipe is provided on the surface of the expansion cover (6), and the connecting pipe is connected to the inner cavity of the expansion cover (6). The mounting base (1) is fixedly installed on the upper side of the template (7) for pouring the underground structure side wall, the connecting sleeve (2) is slidably inserted into the mounting base (1), and the expansion cover (6) is placed in the pouring cavity of the template (7).

2. The anti-concrete cracking device for the sidewall of an underground structure according to claim 1, characterized in that: The expansion cover (6) has a cylindrical hollow structure, and both the upper and lower ends of the expansion cover (6) are conical structures. The expansion cover (6) is made of aluminum plate.

3. The anti-concrete cracking device for the sidewall of an underground structure according to claim 2, characterized in that: A vibrating rod (8) is fixedly installed on the upper surface of the connecting sleeve (2).

4. The anti-concrete cracking device for the sidewall of an underground structure according to claim 3, characterized in that: The connecting pipe includes an input pipe (9) and an output pipe (10). Both the input pipe (9) and the output pipe (10) are fixedly installed on the surface of the connecting sleeve (2). The bottom end of the input pipe (9) extends to the lower part of the inner cavity of the expansion cover (6), and the lower end of the input pipe (9) extends to the upper part of the inner cavity of the expansion cover (6). Both the upper ends of the input pipe (9) and the output pipe (10) are fixedly installed with pipe joints (11).

5. The anti-concrete cracking device for the sidewall of an underground structure according to claim 4, characterized in that: The end of the mounting base (1) is fixedly installed with a guide sleeve (12). The guide sleeve (12) is arranged vertically and has three through holes in its inner cavity. The connecting sleeve (2), the input pipe (9) and the output pipe (10) are slidably inserted into each through hole respectively.

6. The anti-concrete cracking device for the sidewall of an underground structure according to claim 5, characterized in that: A reinforcing cage (13) is installed in the pouring cavity of the template (7). An insertion opening is reserved inside the reinforcing cage (13). The unit probe is inserted into the insertion opening inside the reinforcing cage (13). A flow guiding gap (14) is reserved on the surface of the expansion cover (6) and the inner wall of the template (7).

7. The anti-concrete cracking device for the sidewall of an underground structure according to claim 6, characterized in that: There are multiple mounting bases (1) and unit probes. An installation beam (15) is fixedly installed on the upper side of the template (7). Multiple mounting bases (1) are fixedly installed on the installation beam (15) by bolts. Each unit probe is arranged in parallel and is slidably connected to each mounting base (1).

8. The anti-concrete cracking device for the sidewall of an underground structure according to claim 7, characterized in that: Concrete is poured into the pouring cavity of the template (7), and the concrete covers the expansion cover (6). When the drive motor (4) is started, the spiral blades (5) drive the concrete to flow through the transmission shaft (3).

9. A device for preventing concrete cracking in the sidewall of an underground structure according to claim 7, characterized in that: Concrete is poured into the pouring cavity of the template (7), and the concrete covers the expansion cover (6). When the drive motor (4) and the vibrator (8) are both started, the unit probe moves upward under the reaction force of the concrete pushed by the spiral blade (5) and the vibration of the concrete around the expansion cover (6) driven by the vibrator (8).

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