A safe prefabricated sandbox for elevated bridge construction

Abstract

This invention discloses a safe prefabricated sand box for elevated bridge construction, comprising a sand box body, a cover, a support device, a sand discharge structure, and limiting devices. The upper part of the sand box body has a cavity, and the cover is mounted within the cavity via a sliding connection. The support device is fixedly mounted on the sand box body, with its top end abutting against the cover. The sand discharge structure is located on the outer sidewall of the bottom end of the sand box body, penetrating the sidewall. Several limiting devices are arranged along the movement direction of the cover, with their lower parts fixed to the outer sidewall of the top end of the sand box body, and their upper inner sides abutting against the sidewall of the cover. The height of the cover is precisely adjusted via the support device, and the required amount of sand is accurately indicated by markings inside the support device. This facilitates one-time sand addition by workers, avoiding repeated adjustments of the cover to control the sand quantity and improving work efficiency.

Description

Technical Field

[0001] This invention relates to the field of sand box technology, and specifically to a safe prefabricated sand box for the construction of elevated bridges. Background Technology

[0002] A sand box is a structure used to support building steel beams and other structures. Its working principle is similar to that of a jack. Sand boxes are used when constructing urban viaducts that cross roads to protect the bridge. After the sand box is filled with sand, a cover is placed inside the sand box. At this time, the cover provides temporary support for the bridge structure. Depending on the amount of work, different amounts of sand need to be added to the sand box. Workers need to repeatedly remove and place the cover inside the sand box to control the amount of sand inside. The process is cumbersome, and the cover is heavy, making it inconvenient for workers to repeatedly remove and place the cover inside the sand box. Summary of the Invention

[0003] To address the aforementioned shortcomings of existing technologies, a safe prefabricated sand box for elevated bridge construction is provided, which simplifies the sand filling process and improves the efficiency of workers in adding or removing sand from the sand box.

[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0005] A safe prefabricated sand box for elevated bridge construction is characterized by comprising a sand box body, a cover cylinder, a support device, a sand discharge structure, and limiting devices. The upper part of the sand box body has a cavity that matches the external cross-sectional dimensions of the cover cylinder. The cover cylinder is installed in the cavity of the sand box body via a sliding connection. The support device is fixedly installed on the outer side wall of the sand box body, with its top end abutting against the cover cylinder. The size of the internal space formed by the cover cylinder and the sand box is controlled by adjusting the support device. The sand discharge structure is installed on the outer side wall at the bottom of the sand box body and penetrates through the side wall of the sand box body. Several limiting devices are arranged along the movement direction of the cover cylinder. The lower part of the limiting device is fixedly installed on the outer side wall at the top of the sand box body, and the inner side of the upper part of the limiting device is attached to the side wall of the cover cylinder.

[0006] According to the above technical solution, the support device includes a fixed bracket, a support rod, a limiting component, a fine-tuning component, a support block, and a marking component. The fixed bracket is fixedly installed on the outer side wall of the sand box body. The fixed bracket has a through hole that matches the cross-sectional size of the support rod. The support rod is slidably connected in the through hole of the fixed bracket, and the support rod is parallel to the movement direction of the cover cylinder. The limiting component is installed on the support rod and the fixed bracket to adjust the relative position between them. The fine-tuning component is installed on the support rod, and the support block is installed on the top of the support rod through the fine-tuning component. The marking component is installed at the bottom end of the cover cylinder.

[0007] According to the above technical solution, the limiting component includes mutually matched limiting holes and pins. Several limiting holes are spaced apart on the support rod, and the pins are movably connected to the fixed bracket. According to the usage requirements, the pins are inserted into the corresponding limiting holes.

[0008] According to the above technical solution, a through hole is provided at the position where the fixed bracket matches the limiting hole, and a sliding section matching the size of the through hole is provided on the pin; a positioning rod and a fixing ring are provided at both ends of the sliding section, both of which are larger than the size of the through hole, the fixing ring is located on the side of the limiting hole, and the positioning rod is away from the side of the limiting hole; a first spring is provided on the sliding section, the first spring is sleeved on the sliding section in a stretched state, one end of the first spring is fixed on the fixing ring, and the other end of the first spring is fixed on the fixed bracket.

[0009] According to the above technical solution, the fine-tuning component includes an auxiliary block and a lead screw. An orifice matching the lead screw is provided inside the support rod. The lead screw is placed in the orifice. One end of the lead screw is connected to the support block, and the other end of the lead screw is connected to the auxiliary block. The relative position of the lead screw and the support rod is adjusted by the auxiliary block.

[0010] According to the above technical solution, the marking component includes a sponge ring and protrusions located at the bottom of the cap cylinder. The size of the sponge ring is the same as the size of the cap cylinder, and the protrusions are circumferentially spaced and fixedly arranged on the side wall of the sponge ring. The sponge ring is soaked with marking liquid.

[0011] According to the above technical solution, the sand discharge structure includes a sand discharge hole, a blocking component, and a locking component located on the outer side wall of the sand box body; one end of the blocking component is rotatably connected to the outer side wall of the sand box body, and the other end of the blocking component is placed in the sand discharge hole or on the locking component according to the operation requirements; the locking component is located within the rotation range of the blocking component, and the locking component has two states: locking the blocking component and releasing the blocking component.

[0012] According to the above technical solution, the plugging component includes a support rod, a plug, and a bolt. The support rod has an L-shaped structure. One end of the support rod is rotatably connected to the outer side wall of the sand box body. The other end of the support rod is provided with a threaded hole that matches the sand outlet hole. The bolt passes through the threaded hole and is fixedly connected to the plug. A rubber ring is provided on the outside of the plug. The size of the rubber ring is the same as the size of the sand outlet hole.

[0013] The locking block assembly includes a locking block, a telescopic rod, and a second spring. One end of the telescopic rod is fixed to the outer side wall of the sand box body, and the telescopic rod is within the rotation range of the support rod. The other end of the telescopic rod is connected to the locking block, which has a U-shaped structure with the U-shaped part facing outward. The second spring is sleeved on the telescopic rod in a compressed state. One end of the second spring is fixed to the outer side wall of the sand box body, and the other end of the second spring is fixed to the locking block.

[0014] According to the above technical solution, the limiting device includes a positioning block, a drive rod, a slide rod, and a limiting block assembly. The positioning block is fixedly connected to the arc surface of the outer side of the sand box body. The positioning block is provided with a slide rod hole and a drive rod hole. The slide rod is placed in the slide hole in a sliding connection manner. One end of the slide rod is fixedly connected to the limiting block assembly, and the other end of the slide rod is provided with an anti-detachment head. The size of the anti-detachment head is larger than the cross-sectional size of the slide hole. The drive rod is placed in the drive rod hole in a threaded connection manner. One end of the drive rod is rotatably connected to the limiting block assembly. One side of the limiting block assembly is attached to the side wall of the cover cylinder, and the other side is connected to the sand box body through the drive rod, the slide rod, and the positioning block. Under the action of the drive rod, the limiting block assembly is tightly attached to the side wall of the cover cylinder.

[0015] According to the above technical solution, the limiting block assembly includes a limiting block, a U-shaped frame, and rollers. Several rollers are installed on the side of the limiting block near the cover cylinder via the U-shaped frame. The rollers are all attached to the outer wall of the cover cylinder, thereby limiting the movement direction of the cover cylinder.

[0016] The present invention has the following beneficial effects:

[0017] 1. Based on the usage requirements of the sand box, the height of the cover cylinder is precisely adjusted through the support device. The markings inside the support device accurately indicate the amount of sand to be added, facilitating the one-time addition of sand by the staff and avoiding repeated lifting and lowering of the cover cylinder to control the amount of sand, thus improving the work efficiency of the staff. The limit device is set to make the cover cylinder sink along the same vertical line as the sand box body, thereby reducing the phenomenon of cover cylinder sinking and offset, and improving the use effect of the cover cylinder on the sand box body. The sand discharge structure is set to facilitate the reduction of sand inside the sand box body.

[0018] 2. A support device is set up. The pins are inserted into different limit holes to support the cover tube according to the sand volume requirements. The sponge ring dipped in ink is inserted into the inner wall of the sand box body through the cover tube. The ink on the sponge ring will spread the inside of the sand box body. The staff can spread the sand volume inside the sand box body according to the surface of the ink spread position, which facilitates the staff to control the sand volume at one time.

[0019] 3. A lead screw and an auxiliary block are installed. Rotating the auxiliary block will cause the lead screw to move inside the support rod, which facilitates fine-tuning of the support block's position. By fine-tuning the support block's position, the accuracy of sand quantity control is further improved.

[0020] 4. The plug is installed on the support rod by means of threaded connection. The plug is pulled out or inserted from the sand outlet hole by bolts. Compared with the existing sand outlet hole, there is no thread, which reduces the risk of the hand being scratched by the thread. In addition, a rubber ring is set between the plug and the sand outlet hole, which improves the sealing effect of the plug on the sand outlet hole. The rotatable support rod and the locking block assembly are set to facilitate the suspension of the pulled-out plug.

[0021] 5. A limiting device is installed to guide the running direction of the cover cylinder, ensuring that the cover cylinder sinks along the same vertical line as the sand box body. This reduces the phenomenon of cover cylinder sinking and offset, and improves the usage effect of the cover cylinder on the sand box body. In addition, the relative movement between the cover cylinder and the roller further reduces the friction between the cover cylinder and the limiting block. By setting up a limiting device, the limiting work of the cover cylinder inside the sand box body is facilitated, further improving the sinking effect of the sand box body and the cover cylinder during use. Attached Figure Description

[0022] Figure 1 This is a three-dimensional structural schematic diagram of an embodiment provided by the present invention;

[0023] Figure 2 This is a disassembled structural diagram of an embodiment provided by the present invention;

[0024] Figure 3 This is a schematic diagram of the structure of the sand box body according to an embodiment of the present invention;

[0025] Figure 4 This is a partial structural schematic diagram of the support device provided in an embodiment of the present invention;

[0026] Figure 5 This is an embodiment provided by the present invention. Figure 4 A schematic diagram of the structure at point B;

[0027] Figure 6 This is an embodiment provided by the present invention. Figure 2 A schematic diagram of the structure at point A;

[0028] Figure 7 This is a schematic diagram of the sand discharge structure provided in an embodiment of the present invention;

[0029] Figure 8 This is a schematic diagram of the structure of the limiting device provided in an embodiment of the present invention;

[0030] In the diagram, 1. Sand box body; 2. Cover cylinder; 3. Support device; 301. Support rod; 302. Support block; 303. Fixed bracket; 304. Auxiliary block; 305. Screw rod; 306. Limiting hole; 307. Positioning rod; 308. Fixing ring; 309. First spring; 310. Sponge ring; 311. Protrusion; 4. Sand discharge structure; 41. Support rod; 42. Sand discharge hole; 43. Block; 44. Rubber ring; 45. Bolt; 46. Locking block; 47. Telescopic rod; 48. Second spring; 5. Limiting device; 51. Positioning block; 52. Drive rod; 53. Slide rod; 54. Limiting block; 55. U-shaped frame; 56. Roller. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] Reference Figures 1 to 8 As shown, the present invention provides a safe prefabricated sand box for elevated bridge construction, comprising a sand box body 1, a cover cylinder 2, a support device 3, a sand discharge structure 4, and a limiting device 5. The upper part of the sand box body is provided with a cavity that matches the external cross-sectional dimensions of the cover cylinder. The cover cylinder is provided in the cavity of the sand box body by means of a sliding connection. The support device is fixedly provided on the outer side wall of the sand box body, and the top end of the support device abuts against the cover cylinder. The size of the internal space formed by the cover cylinder and the sand box is controlled by adjusting the support device. The sand discharge structure is provided on the outer side wall of the bottom end of the sand box body and penetrates through the side wall of the sand box body. Several limiting devices are arranged along the movement direction of the cover cylinder. The lower part of the limiting device is fixedly provided on the outer side wall of the top end of the sand box body, and the upper inner side of the limiting device is attached to the side wall of the cover cylinder.

[0033] This embodiment uses a support device to precisely adjust the height of the cover cylinder, and accurately indicates the amount of sand to be added based on the markings inside the support device. This facilitates one-time sand addition by workers, avoiding the need for repeated lifting and lowering of the cover cylinder to control the sand amount, thus improving work efficiency. A sand discharge structure is also included for easy...

[0034] Furthermore, the support device includes a fixed bracket 303, a support rod 301, a limiting component, a fine-tuning component, a support block 302, and a marking component. The fixed bracket is fixedly mounted on the outer side wall of the sand box body. The fixed bracket has a through hole that matches the cross-sectional size of the support rod. The support rod is slidably connected in the through hole of the fixed bracket, and the support rod is parallel to the movement direction of the cover cylinder. The limiting component is located on the support rod and the fixed bracket and is used to adjust the relative position between the two. The fine-tuning component is located on the support rod, and the support block is located on the top of the support rod through the fine-tuning component. The marking component is located at the bottom end of the cover cylinder.

[0035] Furthermore, the limiting component includes mutually matched limiting holes 306 and pins. Several limiting holes are spaced apart on the support rod, and the pins are movably connected to the fixed bracket. According to the usage requirements, the pins are inserted into the corresponding limiting holes.

[0036] Furthermore, a through hole is provided at the position where the fixed bracket matches the limiting hole, and a sliding section matching the size of the through hole is provided on the pin; a positioning rod 307 and a fixing ring 308 are provided at both ends of the sliding section, both of which are larger than the size of the through hole, the fixing ring is located on the side of the limiting hole, and the positioning rod is away from the side of the limiting hole; a first spring 309 is provided on the sliding section, the first spring is sleeved on the sliding section in a stretched state, one end of the first spring is fixed on the fixing ring, and the other end of the first spring is fixed on the fixed bracket.

[0037] Furthermore, the fine-tuning component includes an auxiliary block 304 and a lead screw 305. An orifice matching the lead screw is provided inside the support rod. The lead screw is placed inside the orifice, with one end connected to the support block and the other end connected to the auxiliary block. The relative position of the lead screw and the support rod is adjusted via the auxiliary block. By setting up the lead screw and auxiliary block, rotating the auxiliary block causes the lead screw to move inside the support rod, thus facilitating fine-tuning of the support block's position. This fine-tuning further improves the accuracy of sand quantity control.

[0038] Furthermore, the marking component includes a sponge ring 310 and protrusions 311 located at the bottom of the cover cylinder. The size of the sponge ring is the same as the size of the cover cylinder, and the protrusions are circumferentially spaced and fixedly arranged on the side wall of the sponge ring. The sponge ring is soaked with marking liquid. Marking the inside of the sand box body with the sponge ring facilitates the one-time addition of sand by the staff, avoiding the need for the staff to repeatedly pick up and put down the cover cylinder to control the amount of sand, thus improving the efficiency of the staff in adding sand to the inside of the sand box body.

[0039] By setting up a support device, pulling the positioning rod at the end of the pin will pull the other end of the pin out of the limiting hole, allowing the support rod to slide through the through hole of the fixed bracket. After sliding the support rod to the appropriate position, releasing the positioning rod at the end of the pin will cause the fixing ring in the middle of the pin to be subjected to the elastic force of the first spring in a compressed state, thereby inserting the other end of the pin into the appropriate limiting hole and fixing the position of the support rod after movement.

[0040] Inserting the pins into different limiting holes allows the cover tube to be supported according to the required sand volume. Inserting a sponge ring soaked in ink through the cover tube into the inner wall of the sandbox body, the cover tube can be stopped once it reaches the upper surface of the support block. At this point, the ink on the sponge ring will coat the inside of the sandbox body. The protrusions on the sponge ring press against the inner wall of the sandbox body, improving the clarity of the coating marks. Workers can then evenly distribute the sand volume inside the sandbox body based on the ink coating area, facilitating one-time control of the sand volume. When the cover tube is in place for normal use, pulling the positioning rod again will cause the support rod to fall due to its own weight, facilitating normal use of the cover tube inside the sandbox body.

[0041] Furthermore, the sand discharge structure includes a sand discharge hole 42 on the outer side wall of the sand box body, a blocking component, and a locking block component; one end of the blocking component is rotatably connected to the outer side wall of the sand box body, and the other end of the blocking component is placed in the sand discharge hole or on the locking block component according to the operation requirements; the locking block component is located within the rotation range of the blocking component, and the locking block component has two states: locking the blocking component and releasing the blocking component.

[0042] Furthermore, the plugging assembly includes a support rod 41, a plug 43, and a bolt 45. The support rod has an L-shaped structure. One end of the support rod is rotatably connected to the outer side wall of the sand box body. The other end of the support rod is provided with a threaded hole that matches the sand outlet hole. The bolt passes through the threaded hole and is fixedly connected to the plug. A rubber ring 44 is provided on the outside of the plug. The size of the rubber ring is the same as the size of the sand outlet hole.

[0043] The locking block assembly includes a locking block 46, a telescopic rod 47, and a second spring 48. One end of the telescopic rod is fixed to the outer side wall of the sand box body, and the telescopic rod is within the rotation range of the support rod. The other end of the telescopic rod is connected to the locking block, which has a U-shaped structure with the U-shaped part facing outward. The second spring is sleeved on the telescopic rod in a compressed state. One end of the second spring is fixed to the outer side wall of the sand box body, and the other end of the second spring is fixed to the locking block.

[0044] By setting up a sand discharge structure, when sand needs to be discharged from inside the sand box, the drive rod can be rotated, causing the plug to be pulled out from the inner wall of the sand discharge hole. After the plug is completely pulled out from the inner wall of the sand discharge hole, press the locking block towards the side close to the sand box body, rotate the support rod to the position corresponding to the locking block, and then release the locking block. The "U"-shaped locking block will lock the support rod, thus facilitating the suspension of the removed plug. The sand inside the sand box body will flow out through the sand discharge hole. Using the sand discharge structure of this embodiment, the structure of the sand discharge hole is larger than the hole on the sand box body of the existing structure, thereby improving the sand discharge effect. Furthermore, the use of bolt force to pull the plug out from the inner wall of the sand discharge hole facilitates the opening and closing of the sand discharge hole. The inside of the sand discharge hole no longer has threads compared to existing holes, reducing the risk of hand injuries from the threads. When the plug is inserted into the sand discharge hole, the rubber ring will fill the space between the sand discharge hole and the plug, improving the sealing effect of the plug on the sand discharge hole. By setting up a sand discharge structure, the size of the sand discharge hole is increased without affecting the unblocking of the sand discharge hole, thereby improving the sand discharge efficiency of the sand box body and facilitating the removal of sand from inside the sand box body.

[0045] Furthermore, the limiting device includes a positioning block 51, a drive rod 52, a slide rod 53, and a limiting block assembly. The positioning block is fixedly connected to the arc surface of the outer side of the sand box body. The positioning block is provided with a slide rod hole and a drive rod hole. The slide rod is placed in the slide hole in a sliding connection manner. One end of the slide rod is fixedly connected to the limiting block assembly, and the other end of the slide rod is provided with an anti-detachment head. The size of the anti-detachment head is larger than the cross-sectional size of the slide hole. The drive rod is placed in the drive rod hole in a threaded connection manner. One end of the drive rod is rotatably connected to the limiting block assembly. One side of the limiting block assembly is attached to the side wall of the cover cylinder, and the other side is connected to the sand box body through the drive rod, the slide rod, and the positioning block. Under the action of the drive rod, the limiting block assembly is tightly attached to the side wall of the cover cylinder.

[0046] Furthermore, the limiting block assembly includes a limiting block 54, a U-shaped frame 55, and rollers 56. Several rollers are mounted on the side of the limiting block near the cover cylinder via the U-shaped frame. The rollers are all attached to the outer wall of the cover cylinder, thereby limiting the movement direction of the cover cylinder.

[0047] By setting a limiting device, after the cover cylinder is fitted into the sand box body, rotating the drive rod will cause the limiting block assembly to move closer to the cover cylinder, thereby limiting the cover cylinder. Once the cover cylinder is limited to a position on the same vertical line as the sand box body, the drive rod rotation stops; the sliding rod inside the positioning block restricts the movement direction of the limiting block assembly. After the cover cylinder inside the sand box body is aligned, it can sink along the same vertical line as the sand box body, reducing the phenomenon of cover cylinder sinking and offset, and improving the usability of the cover cylinder on the sand box body. The relative movement between the cover cylinder and the roller further reduces the friction between the cover cylinder and the limiting block. By setting a limiting device, the limiting work of the cover cylinder inside the sand box body is facilitated, further improving the sinking effect of the sand box body and the cover cylinder during use.

[0048] The above are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent changes made in accordance with the claims of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A safe prefabricated sandbox for elevated bridge construction, characterized in that: The system includes a sand box body, a cover cylinder, a support device, a sand discharge structure, and limiting devices. The upper part of the sand box body has a cavity that matches the external cross-sectional dimensions of the cover cylinder. The cover cylinder is located in the cavity of the sand box body through a sliding connection. The support device is fixed on the outer side wall of the sand box body, and the top of the support device rests against the cover cylinder. The size of the internal space formed by the cover cylinder and the sand box is controlled by adjusting the support device. The sand discharge structure is located on the outer side wall at the bottom of the sand box body and penetrates through the side wall of the sand box body. Several limiting devices are arranged along the movement direction of the cover cylinder. The lower part of the limiting device is fixed on the outer side wall at the top of the sand box body, and the inner side of the upper part of the limiting device is attached to the side wall of the cover cylinder. The support device includes a fixed bracket, a support rod, a limiting component, a fine-tuning component, a support block, and a marking component. The fixed bracket is fixedly mounted on the outer side wall of the sand box body. The fixed bracket has a through hole that matches the cross-sectional size of the support rod. The support rod is slidably connected in the through hole of the fixed bracket, and the support rod is parallel to the movement direction of the cover cylinder. The limiting component is located on the support rod and the fixed bracket and is used to adjust the relative position between the two. The fine-tuning component is located on the support rod, and the support block is located on the top of the support rod through the fine-tuning component. The marking component is located at the bottom end of the cover cylinder. The fine-tuning component includes an auxiliary block and a lead screw. An orifice matching the lead screw is provided inside the support rod. The lead screw is placed in the orifice. One end of the lead screw is connected to the support block, and the other end of the lead screw is connected to the auxiliary block. The relative position of the lead screw and the support rod is adjusted by the auxiliary block. The marking component includes a sponge ring and protrusions located at the bottom of the cap. The size of the sponge ring is the same as the size of the cap. The protrusions are circumferentially spaced and fixedly arranged on the side wall of the sponge ring. The sponge ring is soaked with marking liquid.

2. The safety-type prefabricated sand box for elevated bridge construction according to claim 1, characterized in that: The limiting component includes mutually matched limiting holes and pins. Several limiting holes are spaced apart on the support rod, and the pins are movably connected to the fixed bracket. According to the usage requirements, the pins are inserted into the corresponding limiting holes.

3. The safety-type prefabricated sand box for elevated bridge construction according to claim 2, characterized in that: A through hole is provided at the position where the fixed bracket matches the limiting hole, and a sliding section matching the size of the through hole is provided on the pin; a positioning rod and a fixing ring are provided at both ends of the sliding section, both of which are larger than the size of the through hole, the fixing ring is located on the side of the limiting hole, and the positioning rod is away from the side of the limiting hole; a first spring is provided on the sliding section, the first spring is sleeved on the sliding section in a stretched state, one end of the first spring is fixed on the fixing ring, and the other end of the first spring is fixed on the fixed bracket.

4. The safety-type prefabricated sand box for elevated bridge construction according to claim 1, characterized in that: The sand discharge structure includes a sand discharge hole, a blocking component, and a locking component located on the outer side wall of the sand box body. One end of the blocking component is rotatably connected to the outer side wall of the sand box body, and the other end of the blocking component is placed in the sand discharge hole or on the locking component according to the operation requirements. The locking component is located within the rotation range of the blocking component and has two states: locking the blocking component and releasing the blocking component.

5. The safety-type prefabricated sand box for elevated bridge construction according to claim 4, characterized in that: The plugging assembly includes a support rod, a plug, and a bolt. The support rod has an L-shaped structure. One end of the support rod is rotatably connected to the outer side wall of the sand box body. The other end of the support rod has a threaded hole that matches the sand outlet hole. The bolt passes through the threaded hole and is fixedly connected to the plug. A rubber ring is provided on the outside of the plug. The size of the rubber ring is the same as the size of the sand outlet hole. The locking block assembly includes a locking block, a telescopic rod, and a second spring. One end of the telescopic rod is fixed to the outer side wall of the sand box body, and the telescopic rod is within the rotation range of the support rod. The other end of the telescopic rod is connected to the locking block, which has a U-shaped structure with the U-shaped part facing outward. The second spring is sleeved on the telescopic rod in a compressed state. One end of the second spring is fixed to the outer side wall of the sand box body, and the other end of the second spring is fixed to the locking block.

6. The safety-type prefabricated sand box for elevated bridge construction according to claim 1, characterized in that: The limiting device includes a positioning block, a drive rod, a slide rod, and a limiting block assembly. The positioning block is fixedly connected to the arc surface of the outer side of the sand box body. The positioning block has a slide rod hole and a drive rod hole. The slide rod is slidably placed in the slide hole. One end of the slide rod is fixedly connected to the limiting block assembly, and the other end of the slide rod is provided with an anti-detachment head. The size of the anti-detachment head is larger than the cross-sectional size of the slide hole. The drive rod is threadedly placed in the drive rod hole, and one end of the drive rod is rotatably connected to the limiting block assembly. One side of the limiting block assembly is attached to the side wall of the cover cylinder, and the other side is connected to the sand box body through the drive rod, the slide rod, and the positioning block. Under the action of the drive rod, the limiting block assembly is tightly attached to the side wall of the cover cylinder.

7. The safety-type prefabricated sand box for elevated bridge construction according to claim 6, characterized in that: The limiting block assembly includes a limiting block, a U-shaped frame, and rollers. The outer side of the limiting block is connected to the drive rod and the slide rod. Several rollers are installed on the inner side of the limiting block near the cover cylinder via the U-shaped frame. The rollers are all in contact with the outer wall of the cover cylinder, thereby limiting the movement direction of the cover cylinder.

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