A connection structure for internal cast-in-place piles in thick raft foundations, where the reinforcing bars also serve as supports.

Abstract

This utility model discloses a connection structure in which the lifting bar of a cast-in-place pile in a thick raft foundation also serves as a support, relating to the field of foundation technology. It includes a cast-in-place pile body and lifting bars located within the pile body for positioning the reinforcing cage. The lifting bars are straightened after the pile head is broken. The lifting bars are marked with elevation control points required for raft support, which are determined by measuring instruments. When the length of the lifting bar is less than the required length for raft support, U-shaped bars are welded to it. The lifting bars and U-shaped bars together constitute the support structure for the raft reinforcement. This utility model integrates the lifting bars of the reinforcing cage and the raft support into a single component, eliminating the need for purchasing, transporting, and installing independent steel supports or stirrups in traditional processes. It also eliminates the need for additional support steel, saving both construction costs and time.

Description

Technical Field

[0001] This utility model relates to the field of foundation and substructure technology, and in particular to a connection structure in which the reinforcing bars of cast-in-place piles in a thick raft foundation also serve as supports. Background Technology

[0002] During the construction of cast-in-place piles, the positioning accuracy of the reinforcing cage directly affects the construction quality. Therefore, it is necessary to install lifting bars to fix the reinforcing cage. The lifting bars act as a "stabilizing force" for the reinforcing cage, precisely suspending it in the preset position to ensure that the cage remains vertical and stable during drilling and concrete pouring, preventing tilting or displacement. In existing technologies, the length of the lifting bars for cast-in-place piles is typically 10d longer than the pile head reinforcing bars (d being the diameter of the lifting bar). After the concrete pouring is completed, when the pile head is subsequently removed, the portion of the lifting bars exceeding the pile head reinforcing bars needs to be cut off or bent according to the arrangement requirements of the pile head reinforcing bars.

[0003] On the other hand, due to the need to bear the enormous load of the superstructure, the thickness of a thick raft foundation typically exceeds 1.5m, with a large amount of internal steel reinforcement and multiple layers. Furthermore, to enhance the overall bearing capacity of the raft foundation, numerous cast-in-place piles are usually densely arranged within the thick raft foundation. In the reinforcement construction of thick raft foundations, existing technologies require the separate installation of horseshoe supports or temporary steel scaffolds to support the upper layers of reinforcement.

[0004] In summary, in existing technologies, redundant portions of the lifting bars in cast-in-place piles are often wasted, and the support system for thick raft foundations still relies on additional stirrups or temporary steel supports, resulting in high construction costs and long construction periods. Therefore, there is an urgent need for a technical solution that enables deep reuse of the lifting bar function and standardized construction to address the pain points of existing technologies. Utility Model Content

[0005] This utility model provides a connection structure for the internal cast-in-place pile suspension bars to also serve as supports in thick raft foundations, which solves the technical problems of inconsistent welding height of U-shaped bars, waste of steel support materials and long construction period caused by the single function of suspension bars.

[0006] To solve the above-mentioned technical problems, this utility model provides a connection structure for the lifting bars of cast-in-place piles in a thick raft foundation, which also serve as supports. The structure includes a cast-in-place pile body and lifting bars located within the pile body for positioning the reinforcing cage. The lifting bars are straightened after the pile head is broken. The lifting bars are marked with elevation control points required for raft support, which are determined by measuring instruments. When the length of the lifting bar is less than the required length for raft support, U-shaped bars are welded onto the lifting bars. The lifting bars and U-shaped bars together constitute the support structure for the raft reinforcement.

[0007] Preferably, when cutting the U-shaped bar, in addition to meeting the standard length for welding steel bars, an extra length of 50-100mm is left; when the length deviation of the hanging bars 3 on both sides exceeds the extra length, vertical steel bars are welded between the U-shaped bar and the hanging bars.

[0008] Preferably, the lifting bar is bent along the elevation control point by a steel bar bending machine, and the bending angle of the lifting bar along the elevation control point is 90 degrees to form a horizontal support section.

[0009] Preferably, the connection structure further includes horizontal reinforcement bars, wherein the overlap length of the horizontal support sections of adjacent suspension bars is [not specified]. Then there is no need to add horizontal reinforcement; if the lap length of the horizontal support section of the adjacent suspension reinforcement is... Then, the horizontal reinforcing bars are tied and fixed between the horizontal support sections of adjacent suspension bars, wherein, This refers to the diameter of the suspension rod.

[0010] Preferably, the lifting bars are combined with U-shaped bars, horizontal bars or vertical bars to form a support grid.

[0011] Preferably, the elevation control points are painted with red paint.

[0012] Compared with related technologies, the connection structure of the cast-in-place pile suspension bar that also serves as a support in the thick raft foundation provided by this utility model has the following beneficial effects:

[0013] This utility model provides a connection structure for the lifting bars of the cast-in-place piles in a thick raft foundation to also serve as supports. By integrating the lifting bars of the steel cage with the raft foundation support into the same link, it eliminates the need for purchasing, transporting and installing independent steel supports or stirrups in traditional processes. It also eliminates the need for additional support steel, thus saving both construction costs and construction time.

[0014] This utility model provides a connection structure for the internal cast-in-place pile suspension bars to serve as supports in thick raft foundations. By using measuring instruments to precisely mark the elevation and employing a standardized U-shaped bar welding process, the consistent height of the support structure is ensured. The design of the excess length of the U-shaped bars and the welding of the vertical reinforcing bars can accommodate different suspension bar length deviations, making it suitable for the construction of thick raft foundations under various geological conditions. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the suspension rod structure of this utility model;

[0016] Figure 2 This is a schematic diagram of the welded U-shaped rib structure of the lifting rib of this utility model;

[0017] Figure 3 This is a schematic diagram of the overlapping structure of the suspension rods of this utility model;

[0018] Figure 4This is a schematic diagram of the structure of the suspension rod and horizontal reinforcement of this utility model;

[0019] Figure 5 This is a schematic diagram of the U-shaped bar combined with the vertical steel bar structure of this utility model.

[0020] The following are the labels in the diagram: 1. Cast-in-place pile body; 2. Reinforcing cage; 3. Hanging bar; 4. Elevation control point; 5. U-shaped bar; 6. Horizontal bar; 7. Vertical bar. Detailed Implementation

[0021] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0022] Example

[0023] Reference Figure 1-5 This embodiment provides a connection structure for the lifting bars of cast-in-place piles in a thick raft foundation, which also serve as supports. The structure includes a cast-in-place pile body 1 and lifting bars 3 located within the pile body 1 for positioning the reinforcing cage 2. The lifting bars 3 are straightened after the pile head is removed. Elevation control points 4, required for raft foundation support, are marked on the lifting bars 3 and determined using measuring instruments. When the length of the lifting bars 3 is less than the required length for raft foundation support, U-shaped bars 5 are welded onto the lifting bars 3. The lifting bars 3 and U-shaped bars 5 together constitute the support structure for the raft foundation reinforcement. When the U-shaped bars 5 are cut, in addition to meeting the standard length for reinforcing bar welding, a 50-100mm margin is left. When the length deviation of the lifting bars 3 on both sides exceeds the margin, vertical reinforcing bars 7 are welded between the U-shaped bars 5 and the lifting bars 3. The lifting bars 3 are bent along the elevation control points 4 using a reinforcing bar bending machine, with the bending angle being 90 degrees, forming a horizontal support section. It also includes horizontal reinforcement 6, if the lap length of the horizontal support section of the adjacent suspension reinforcement 3 is... Then there is no need to add horizontal reinforcement 6; if the overlap length of the horizontal support section of the adjacent suspension reinforcement 3 is... The horizontal reinforcing bars 6 are then tied and fixed between the horizontal support sections of adjacent suspension bars 3, wherein... The diameter of the lifting bar 3 is specified. The cast-in-place pile body 1 is densely distributed within the thick raft foundation, with a pile spacing ≤ 3 times the pile diameter. The lifting bars 3, together with U-shaped bars 5, horizontal bars 6, or vertical bars 7, form a support grid.

[0024] The cast-in-place pile body 1 provides vertical bearing capacity for the thick raft foundation, and the internal steel reinforcement cage 2 is the core component for improving the structural strength of the cast-in-place pile. The positioning accuracy of the steel reinforcement cage 2 directly affects the load-bearing performance of the cast-in-place pile. In this embodiment, the diameter of the cast-in-place pile body 1 is preferably 800mm, the pile spacing is 2.0m (≤3 times the pile diameter), and it is cast with C35 concrete. The steel reinforcement cage 2 is composed of longitudinal steel bars and stirrups to ensure overall rigidity.

[0025] When the lifting rod 3 is used as a positioning component, one end of the lifting rod 3 is welded and fixed to the top of the reinforcing cage 2 (double-sided welding, welding length 5d), and the other end extends to the opening to suspend the reinforcing cage 2, ensuring that it remains vertical during concrete pouring. When used as a support component, the lifting rod 3 is straightened, marked with elevation, and bent to form a support frame. The straightening process uses mechanical straightening methods, such as a reinforcing bar straightening machine, to avoid deviations in support height caused by bending.

[0026] Elevation control point 4 is a key marker for achieving precise support of the hanger 3, used to determine the bending position and support height of the hanger 3. In this embodiment, elevation control point 4 is determined by measuring instruments such as a laser level, which improves accuracy compared to traditional line-laying methods; the marker is painted with red paint, which is clear and durable, ensuring the accuracy of subsequent bending operations and preventing the upper layer of reinforcement in the raft slab from sinking due to elevation deviation.

[0027] U-shaped reinforcement 5 is used to compensate for the insufficient length of the hanger reinforcement 3. Its shape is "U". The vertical section is welded to the hanger reinforcement 3, and the horizontal section works with the bent horizontal support section of the hanger reinforcement 3 to support the raft slab reinforcement. The material is matched to that of the hanger reinforcement 3 to ensure welding strength. A 50-100mm allowance is left during cutting; this range has been verified in engineering projects to accommodate over 90% of hanger reinforcement length deviations, avoiding material waste and ensuring adjustable support height.

[0028] Horizontal reinforcement 6 is used to enhance the connection strength of the horizontal support sections of adjacent hanger reinforcement 3. When the lap length of the horizontal support sections of adjacent hanger reinforcement 3 is... At this time, the horizontal reinforcement 6 can fill the lap gap and form a continuous support surface. In this embodiment, the horizontal reinforcement 6 is tied and fixed with the hanger reinforcement 3 to ensure cooperative stress performance.

[0029] The vertical reinforcing bar 7 serves as a supplementary adjustment component to the U-shaped bar 5. When the length deviation of the hanging bars 3 on both sides exceeds the allowable length of the U-shaped bar 5, the support height can be precisely adjusted by welding the vertical reinforcing bar 7, preventing support failure due to hanging bar length errors. The diameter of the vertical reinforcing bar 7 is the same as that of the U-shaped bar 5, and the welding method is single-sided welding. Ensure the connection strength with U-shaped reinforcement 5 and hanging reinforcement 3.

[0030] In the densely distributed area of ​​the cast-in-place pile body 1 (pile spacing ≤ 3 times the pile diameter), the lifting bar 3, U-shaped bar 5, horizontal bar 6, and vertical bar 7 work together to form an overall support grid. This grid can replace the traditional stirrup bar or temporary steel support, and its overall rigidity is stronger than that of the traditional support system.

[0031] Implementation steps:

[0032] This embodiment is applied to the construction of a thick raft foundation. The raft foundation is 2.5m thick, and the design elevation is from -4.0m to -6.5m. The specific steps are as follows:

[0033] 1. Construct the cast-in-place pile body 1 according to the design drawings. When hoisting the reinforcing cage 2, weld one end of the hoisting bar 3 to the top of the reinforcing cage 2 and extend the other end to the borehole and temporarily fix it. After the cast-in-place pile concrete is poured, cure it to the design strength.

[0034] 2. Use a pneumatic hammer to break the pile head down to the design elevation of the raft foundation bottom, clear debris from the pile head, and expose the redundant part of the lifting reinforcement 3. Use a rebar straightening machine to straighten the lifting reinforcement 3 to ensure that the straightness meets the requirements.

[0035] 3. Measure and mark the elevation control point 4 on the suspension rod 3 using a horizontal laser measuring instrument, and spray the marking line with red paint.

[0036] 4. Construct a supporting structure

[0037] (1) The top of the U-shaped bar 5 and the hanging bar 3 are directly welded by arc welding.

[0038] (2) If the length deviation of the suspension bar 3 exceeds 100mm of excess length, weld vertical steel bar 7 between the U-shaped bar 5 and the suspension bar 3 to ensure that the support height is -4.0m.

[0039] (3) Use a steel bar bending machine to bend the hanger bar 3 at 90 degrees along the elevation control point 4 to form a horizontal support section. Check the lap length of the horizontal support sections of adjacent hanger bars 3.

[0040] ① Overlap length The overlapping area is welded directly;

[0041] ② Overlap length After binding 6 horizontal reinforcing bars in between, welding was performed.

[0042] 6. Place the upper layer of steel reinforcement in the raft slab onto the support grid to complete the application of the support system.

[0043] This embodiment achieves functional reuse of the suspension rod 3 through the above structure and steps, saving 8.5t of steel and shortening the construction period by 4 days compared with the traditional process, while the support accuracy meets the design requirements.

Claims

1. A connection structure for internal cast-in-place piles in a thick raft foundation, which also serves as a support, characterized in that: The system includes a cast-in-place pile body and lifting bars located within the cast-in-place pile body for positioning the reinforcing cage. The lifting bars are straightened after the pile head is broken. The lifting bars are marked with elevation control points required for raft support, and these elevation control points are determined by measuring instruments. When the length of the lifting bars is less than the required length for raft support, U-shaped bars are welded onto the lifting bars. The lifting bars and U-shaped bars together constitute the support structure for the raft reinforcement.

2. The connection structure for the internal cast-in-place pile suspension bars serving as supports in a thick raft foundation according to claim 1, characterized in that, When cutting the U-shaped bar, in addition to meeting the length requirements of the bar welding specifications, an extra length of 50-100mm is left; when the length deviation of the lifting bars on both sides exceeds the extra length, vertical bars are welded between the U-shaped bar and the lifting bars.

3. The connection structure for the internal cast-in-place pile suspension bars serving as supports in a thick raft foundation according to claim 1, characterized in that, The lifting bar is bent along the elevation control point by a steel bar bending machine, and the bending angle of the lifting bar along the elevation control point is 90 degrees to form a horizontal support section.

4. The connection structure for the internal cast-in-place pile suspension bars serving as supports in a thick raft foundation according to claim 3, characterized in that, The connection structure also includes horizontal reinforcement bars, if the lap length of the horizontal support sections of adjacent suspension bars is... Then there is no need to add horizontal reinforcement; if the lap length of the horizontal support section of the adjacent suspension reinforcement is... The horizontal reinforcing bars are then tied and fixed between the horizontal support sections of adjacent suspension bars, wherein... This refers to the diameter of the suspension rod.

5. The connection structure for the internal cast-in-place pile suspension bar as a support in a thick raft foundation according to claim 1, characterized in that, The suspension bars are combined with U-shaped bars, horizontal bars, or vertical bars to form a support grid.

6. The connection structure for the internal cast-in-place pile suspension bars serving as supports in a thick raft foundation according to claim 1, characterized in that, The elevation control points were painted with red paint.

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