Mass concrete construction method combining warehouse jumping method and prestress technology
By combining the jumping method and prestressing technology, the use of pre-made and post-made prestressed bars in large-volume concrete construction solves the problem of difficult to control expansion and contraction effects and achieves high-quality and high-efficiency construction.
Patent Information
- Application Number
- CN202411738214.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-29
- Publication Date
- 2025-01-21
AI Technical Summary
When the existing warehouse jump method is constructed with large volume concrete, it is difficult to effectively control the expansion and contraction effects, resulting in cracks, which cannot meet the construction requirements of ultra-long and ultra-large concrete structures.
Combining the jumping method and prestressing technology, by setting up prestressed tendons and post-stressed tendons in the concrete construction area, the prestressed tendons are used to apply pressure during the heat expansion stage of the concrete to reduce the occurrence of temperature cracks; Prestressed tendons are used to apply tension or restraint during the shrinkage stage of concrete to reduce the occurrence of shrinkage cracks.
It effectively reduces the risk of cracks in large-volume concrete when developing strength, improves construction quality and efficiency, allows first-pouring silos and post-pouring silos to reach larger sizes, and shortens the construction period.
Smart Images
Figure CN119332933A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of mass concrete construction, and in particular to a mass concrete construction method combining a skip bin method and a prestressed technology. Background Art
[0002] my country's "Massive Concrete Construction Standard" GB50496-2018 stipulates: Large-volume concrete with a minimum geometric dimension of not less than 1m, or concrete that is expected to cause harmful cracks due to temperature changes and shrinkage caused by hydration of cementitious materials in the concrete, is called massive concrete.
[0003] When concrete undergoes hydration reaction and expands due to heat, the surface coefficient of concrete is relatively small, the heat of cement hydration is released more concentratedly, and the internal temperature rises faster. When the temperature difference between the inside and outside of concrete is large, temperature cracks will appear in concrete. When the hydration reaction of concrete slows down and enters the shrinkage stage, shrinkage cracks are prone to occur due to factors such as rapid water loss, uncoordinated local shrinkage, and improper maintenance. The above cracks will affect the safety and normal use of the structure.
[0004] In order to ensure the construction quality of large-volume concrete, scholars have proposed the construction organization technology of the skipping method: it uses the principle of "resistance and release" characteristics of concrete that is easy to release internal stress before the performance is not stable and not completely solidified during 5 to 10 days, and divides the building foundation or large-area concrete plane structure into several areas. The construction is carried out according to the principle of "block planning, block construction, layered pouring, and overall forming". Its mode is the same as that of checkers, that is, pouring one section at a time. The construction interval between two adjacent areas is not less than 7 days to avoid the drastic temperature difference and drying effect of the concrete in the early stage of construction.
[0005] With the rapid development of social economy, the volume of construction projects is getting larger and larger, which puts higher requirements on the construction of large-volume concrete. However, the existing skipping method can no longer meet the construction requirements of ultra-long and ultra-large concrete structures due to crack control, both in terms of construction efficiency and construction quality. Based on this technical problem, it is necessary to study a method that can improve the construction efficiency and quality of large-volume concrete based on the existing skipping method. Summary of the invention
[0006] The main technical problem to be solved by the present invention is to provide a construction method for mass concrete, reduce expansion and contraction effects to reduce the generation of cracks, and thus improve construction quality and construction efficiency.
[0007] In order to solve the above technical problems, the present invention provides a mass concrete construction method combining the skipping bin method and the prestressing technology, comprising the following steps:
[0008] Step 1: Based on the skip bin method, the construction area of the mass concrete is divided into a first pouring bin and a second pouring bin; the first pouring bin and the second pouring bin are arranged in a chessboard-like staggered manner;
[0009] Step 2: Arrange conventional stress-bearing steel bars in the construction area according to the design drawings, and reserve prestressed steel bars;
[0010] The prestressed tendons include first prestressed tendons and later prestressed tendons;
[0011] The first prestressed tendons are arranged throughout the first pouring bin and the second pouring bin; at least the first prestressed tendons in the first pouring bin are tensioned, and both ends are constrained;
[0012] The post-cast prestressed tendons are placed at least throughout the length of the first casting bin; the post-cast prestressed tendons are in a natural state;
[0013] Step 3: pouring concrete into the first pouring bin and maintaining it;
[0014] Step 4: When the concrete in the first pouring bin enters the heat release expansion stage and reaches a strength that can be used for tensioning construction, the constraints on the two ends of the first prestressed tendons at the outer edge of the first pouring bin are released;
[0015] Step 5: When the concrete in the first pouring bin enters the shrinkage stage, the subsequent prestressed tendons are tensioned;
[0016] Step 6: pouring concrete into the post-casting bin and maintaining it;
[0017] Before step 6, the prestressed tendons of the post-casting bin are tensioned and constrained at both ends;
[0018] Step 7: When the concrete in the post-casting bin enters the heat release expansion stage and reaches a strength that can be used for tensioning construction, the constraints on both ends of the prestressed tendons at the outer edge of the post-casting bin are released;
[0019] Step 8: Perform closing construction on the first pouring bin and the second pouring bin to connect them into a whole.
[0020] In a preferred embodiment, in step 2, the post-cast prestressed tendons are placed only throughout the entire length of the first-cast bin, and both ends extend a certain length into the post-cast bin.
[0021] In a preferred embodiment, in step 2, the post-cast prestressed tendons are placed throughout the entire length of part or all of the post-casting bins;
[0022] Furthermore, there is an intermediate step 78 between step 7 and step 8: when the concrete in the post-casting bin enters the shrinkage stage, the two ends of the post-casting prestressed tendons placed throughout the length of the post-casting bin are constrained.
[0023] In a preferred embodiment, a construction joint is provided between any adjacent first pouring bin and the second pouring bin.
[0024] In a preferred embodiment, there is an intermediate step 12 between step 1 and step 2: arranging support frames at the periphery of the construction area and in the construction joint.
[0025] In a preferred embodiment, the support frame includes transverse frame ribs and vertical frame ribs;
[0026] A plurality of transverse structural reinforcements are arranged along the periphery of the construction area and the extension direction of the construction joint; the transverse structural reinforcements are welded and connected at the intersection, and the vertical structural reinforcements are buried underground from the intersection.
[0027] In a preferred embodiment, in step 2 and step 6, the implementation method of constraining the two ends of the prestressed tendons is that the two ends of the prestressed tendons are welded to the support frame.
[0028] In a preferred embodiment, in step 8, the closed construction is implemented by pouring concrete into the construction joint and curing it.
[0029] In a preferred embodiment, in step 2, the arrangement direction of the prestressed tendons is parallel or perpendicular to the edge of the first casting bin or the second casting bin.
[0030] In a preferred embodiment, the strength of the mass concrete that can be tensioned is no less than 75% of the designed strength.
[0031] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:
[0032] The construction method provided by the present invention cleverly combines the existing skip bin method and prestressing technology. The first prestressed tendons are used to apply pressure to the concrete in the heat release expansion stage to reduce the generation of temperature cracks; the later prestressed tendons are used to apply tension or constraint to the concrete in the contraction stage to reduce the generation of shrinkage cracks. Therefore, the construction method effectively reduces the risk of cracks in large-volume concrete when developing strength, and improves the construction quality. Furthermore, since the cracks can be effectively controlled, the first pouring bin and the later pouring bin are allowed to reach a larger size, and the same construction area can be divided into fewer bin blocks, thereby shortening the construction period and improving construction efficiency. In addition, the various types of prestressed tendons of the construction method are arranged at one time, and work in batches in subsequent processes, with clear organization and simplified processes, thereby improving construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Figure 1 It is a plan view of step 1 of embodiment 1 of the present invention;
[0034] Figure 2 It is a plan view of an intermediate step 1 of the first embodiment of the present invention;
[0035] Figure 3 It is a schematic elevation view of the intermediate step 1 of the first embodiment of the present invention;
[0036] Figure 4 It is a plan view of step 2 of embodiment 1 of the present invention;
[0037] Figure 5 It is a plan view of steps 3 to 5 of the first embodiment of the present invention;
[0038] Figure 6 It is a plan view of steps 6 to 7 of the first embodiment of the present invention;
[0039] Figure 7 It is a plan view of step 8 of the first embodiment of the present invention;
[0040] Figure 8 It is a plan view of the intermediate step 2 of the second embodiment of the present invention.
[0041] For ease of viewing, the figure only shows one arrangement direction of the prestressed tendons, and does not limit the actual arrangement direction; for ease of understanding, the figure shows the solid lines at the edge of the bin block where concrete has been poured.
[0042] Markings in the figure are: 1-construction area, 11-first pouring bin, 12-later pouring bin, 13-construction joint, 2-support frame, 21-transverse structural reinforcement, 22-vertical structural reinforcement, 3-prestressed reinforcement, 31-first prestressed reinforcement, 32-later prestressed reinforcement; A-first cutting point, B-second cutting point. DETAILED DESCRIPTION
[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.
[0044] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.
[0045] In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installed", "provided with", "installed / connected", "connected", etc. should be understood in a broad sense. For example, "connection" can be a wall-mounted connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be a direct connection or an indirect connection through an intermediate medium. It can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.
[0046] Embodiment 1
[0047] like Figure 1 to Figure 7 As shown, an embodiment of the present invention provides a mass concrete construction method combining the skipping bin method and the prestressing technology, comprising the following steps:
[0048] Step 1: According to the construction requirements, the bulk concrete is divided into blocks based on the skip-bin method. Figure 1 As shown, like a chessboard, a large area of concrete construction area 1 is divided into a number of square bins in the plane for block construction. A construction joint 13 is set between any two adjacent bins. The skip bin method is a mature construction method in the technical field, and the specific bin division method is not described in detail in this article.
[0049] In this embodiment, a part of the bin blocks are defined as the first-cast bins 11, and the remaining bin blocks are defined as the second-cast bins 12. The first-cast bins 11 and the second-cast bins 12 are arranged in a chessboard-like staggered manner. Analogous to the staggered white squares on a chessboard, there are no borders between any adjacent first-cast bins 11. Similarly, analogous to the staggered black squares on a chessboard, there are no borders between any adjacent second-cast bins 12.
[0050] Intermediate step 1: Arrange the support frame 2 at the periphery of the construction area 1 and in the construction joint 13. Figure 2 and Figure 3 As shown, in this embodiment, the support frame 2 includes a plurality of transverse frame ribs 21 and vertical frame ribs 22. The transverse frame ribs 21 are used to fix the subsequent prestressed tendons 3, and therefore must meet certain bearing capacity requirements. A plurality of transverse frame ribs 21 are arranged along the periphery of the construction area 1 and the extension direction of the construction joint 13. The transverse frame ribs 21 are welded and connected at the positions where they intersect with each other, and the vertical frame ribs 22 are buried underground from the intersections to construct a stable rigid spatial structure. The top of the vertical frame rib 22 is welded to the transverse frame rib 21, and the bottom is buried below the ground. The specific burial depth depends on the specific project profile.
[0051] In this article, since the actual construction sequence does not completely correspond to the protection priority of the claims, the intermediate step 1 described in this specification is equivalent to the intermediate step 2 in the claims.
[0052] Step 2: Arrange conventional stress-bearing steel bars in each bin block according to the design drawings, and set prestressed tendons 3 according to the construction plan. The prestressed tendons 3 include first prestressed tendons 31 and second prestressed tendons 32.
[0053] Specifically, Figure 4 As shown, the prestressed tendons 3 are arranged along the length direction, width direction or both length and width directions of the first pouring bin 11 and the second pouring bin 12, and then the first prestressed tendons 31 are tensioned. The first prestressed tendons 31 in the first pouring bin 11 and the second pouring bin 12 can be arranged as a whole and tensioned at one time, or can be arranged separately and tensioned in batches. After the tensioning is completed, the two ends of the first prestressed tendons 31 are welded to the transverse frame ribs 21 to maintain the pre-tensioned state.
[0054] The post-cast prestressed tendons 32 are placed along the length direction, width direction or both length and width directions of the first-cast bin 11 or the post-cast bin 12, and are in a natural state. The post-cast prestressed tendons 32 are placed only along the entire length of the first-cast bin 11, and both ends extend into the post-cast bin 12. Preferably, the post-cast prestressed tendons 32 extending into the post-cast bin 12 can be bent. The specifications, arrangement spacing and tensioning amount of the first-cast prestressed tendons 31 and the post-cast prestressed tendons 32 need to be determined according to the specific project overview and the size of the bin block.
[0055] Step 3: pouring concrete into the first pouring bin 11 and performing curing.
[0056] Step 4: Figure 5 As shown, when the concrete strength of the first casting bin 11 reaches 75% to 80% of the design strength, the concrete can be tensioned, and at this time, the first prestressed tendons 31 of the first casting bin 11 and the transverse frame tendons 21 are cut off at the first cutting point A, so that the first prestressed tendons 31 in the first casting bin 11 are contracted. It should be understood that the transverse frame tendons 21 still maintain a complete shape.
[0057] This stage is generally 3 to 4 days after the concrete is poured, and the concrete enters the hydration heat release expansion stage. Due to the difference in internal and external heat dissipation conditions, large-volume concrete produces a large internal and external temperature difference, and the large internal and external temperature difference causes the internal and external expansion of the concrete to be different. This uncoordinated deformation is easy to form a certain tensile stress inside the concrete, leading to the generation of temperature cracks. Therefore, by releasing the end constraints of the prestressed tendons 31, the prestressed tendons 31 can be restored to shrink while squeezing the concrete inward to buffer the expansion effect inside the concrete, reduce the deterioration of the internal and external shapes, and thus reduce the generation of temperature cracks.
[0058] Step 5: When the hydration heat reaction of the concrete in the first pouring bin 11 slows down and enters the shrinkage stage, the subsequent prestressed tendons 32 are tensioned. Preferably, the ends of the tensioned subsequent prestressed tendons 32 are welded to the transverse frame tendons 21.
[0059] During this stage, shrinkage cracks are prone to occur in the mass concrete during the shrinkage process due to factors such as excessive water loss, uncoordinated local shrinkage, and improper maintenance. Therefore, at this time, the tensioning of the post-made prestressed tendons 32 can provide a tensile force from the inside to the outside to the concrete; at the same time, the two ends of the post-made prestressed tendons 32 are constrained after tensioning, and the tendency of the concrete to shrink inward is restricted by the bonding force between the post-made prestressed tendons 32 and the post-made prestressed tendons 32. In this way, the shrinkage effect of the mass concrete is doubly weakened, thereby reducing the occurrence of shrinkage cracks.
[0060] Step 6: Figure 5 As shown, after the concrete in the first pouring bin 11 has reached the curing age, the concrete in the second pouring bin 12 is poured and cured.
[0061] Step 7: Figure 6 As shown, referring to step 5, when the concrete strength of the post-casting bin 12 reaches 75% to 80% of the design strength, the prestressed tendons 31 of the post-casting bin 12 and the transverse frame tendons 21 are cut off at the second cutting point B to shrink the prestressed tendons 31 in the pre-casting bin 11.
[0062] When the hydration heat reaction of the concrete in the post-casting bin 12 slows down and enters the shrinkage stage, the post-casting prestressed tendons 32 located outside the post-casting bin 12 are anchored in the concrete of the first-casting bin 11 or welded to the transverse frame tendons 21, so that the end of the prestressed tendons 32 bent and anchored in the concrete of the post-casting bin 12 can hook the concrete, and the bonding effect between the steel bars and the concrete is used to restrain the concrete from shrinking inward. Therefore, the shrinkage effect of the concrete in the post-casting bin 12 can be weakened without additional construction.
[0063] Step 8: Figure 7As shown, after the concrete construction of all the bin blocks is completed, the concrete in the construction joint 13 is poured and cured to connect the first pouring bin 11 and the second pouring bin 12 as a whole.
[0064] In step 8, the prestressed tendons 3 and the transverse frame tendons 21 exposed on the concrete surface should be handled flexibly: the exposed prestressed tendons 3 can be cut off or bent and anchored in the construction joint 13; the transverse frame tendons 21 can be removed as a whole or buried in the construction joint 13 with the outer part cut off.
[0065] It is understandable that the prestressed tendons 31 are tensioned and fixed before concrete pouring, so as not to affect the construction of concrete. Therefore, the prestressed tendons 31 in the post-casting bin 12 in step 2 can also be tensioned and fixed between step 5 and step 6.
[0066] It is understandable that, for ultra-large concrete structural projects, the first pouring bin 11 and the second pouring bin 12 can be constructed in batches. In other words, assuming that the construction area 1 of a certain structural project is divided into 10 first pouring bins 11 and 10 second pouring bins 12, 5 first pouring bins 11 and 5 second pouring bins 12 can be constructed first, and then the remaining 5 first pouring bins 11 and 5 second pouring bins 12 can be constructed. This transformation should be regarded as a homogeneous transformation.
[0067] Embodiment 2
[0068] like Figure 8 As shown, the embodiment of the present invention provides a large-volume concrete construction method combining the skip bin method and prestressing technology. The difference between the construction method and the first embodiment is that: in the step 2, the post-cast prestressed tendons 32 are placed in all the first-cast bins 11 and are also placed in part or all of the post-cast bins 12. Furthermore, there is an intermediate step 2 between the steps 7 and 8: when the concrete hydration heat reaction in the post-cast bin 12 slows down and enters the shrinkage stage, the end of the post-cast prestressed tendons 32 placed in the post-cast bin 12 is welded to the transverse frame reinforcement 21.
[0069] Similarly, because the actual construction sequence does not completely correspond to the protection priority of the claims, the intermediate step 2 described in this specification is equivalent to the intermediate step 1 in the claims.
[0070] Except for the above differences, the rest of the mass concrete construction method combining the skip bin method and prestressed technology provided in this embodiment is the same as that in the first embodiment.
[0071] In summary, the large-volume concrete construction method combining the skipping bin method and the prestressing technology provided in the first and second embodiments of the present invention applies the prestressing technology on the basis of the existing skipping bin method. During the heat release and expansion stage of the concrete, the prestressed tendons 31 are used to apply pressure to the concrete to buffer the expansion effect inside the concrete, thereby reducing the generation of temperature cracks. When the concrete enters the shrinkage stage, the post-prestressed tendons 32 are used to apply tension or constraint to the concrete, thereby weakening the shrinkage effect and reducing the generation of shrinkage cracks.
[0072] Therefore, the construction method effectively reduces the risk of cracks in large-volume concrete when developing strength, and improves the construction quality. Furthermore, since the cracks are effectively controlled, the first pouring bin 11 and the second pouring bin 12 are allowed to reach a larger size, and the same construction area 1 can be divided into fewer bins, thereby shortening the construction period and improving the construction efficiency. In addition, the various types of prestressed tendons 3 of the construction method are arranged at one time, and they work in batches in the subsequent process, which has a clear organization, simplified processes, and improved construction efficiency.
[0073] The above description is only a preferred specific implementation mode of the present invention, and does not limit the patent scope of the present invention. Any technical equivalent changes made using the contents of the present invention specification shall fall within the protection scope of the present invention.
Claims
1. A mass concrete construction method combining the skipping method and prestressing technology, characterized in that: The following steps are involved: Step 1: Based on the skip bin method, the construction area of the mass concrete is divided into a first pouring bin and a second pouring bin; the first pouring bin and the second pouring bin are arranged in a chessboard-like staggered manner; Step 2: Arrange conventional stress-bearing steel bars in the construction area according to the design drawings, and reserve prestressed steel bars; The prestressed tendons include first prestressed tendons and later prestressed tendons; The first prestressed tendons are arranged throughout the first pouring bin and the second pouring bin; at least the first prestressed tendons in the first pouring bin are tensioned, and both ends are constrained; The post-cast prestressed tendons are placed at least throughout the length of the first casting bin; the post-cast prestressed tendons are in a natural state; Step 3: pouring concrete into the first pouring bin and maintaining it; Step 4: When the concrete in the first pouring bin enters the heat release expansion stage and reaches a strength that can be used for tensioning construction, the constraints on the two ends of the first prestressed tendons at the outer edge of the first pouring bin are released; Step 5: When the concrete in the first pouring bin enters the shrinkage stage, the subsequent prestressed tendons are tensioned; Step 6: pouring concrete into the post-casting bin and maintaining it; Before step 6, the prestressed tendons of the post-casting bin are tensioned and constrained at both ends; Step 7: When the concrete in the post-casting bin enters the heat release expansion stage and reaches a strength that can be used for tensioning construction, the constraints on both ends of the prestressed tendons at the outer edge of the post-casting bin are released; Step 8: Perform closing construction on the first pouring bin and the second pouring bin to connect them into a whole.
2. A mass concrete construction method combining the skipping bin method and prestressing technology according to claim 1, characterized in that: In step 2, the post-cast prestressed tendons are placed only throughout the entire length of the first-cast bin, and both ends extend a certain length into the post-cast bin.
3. A mass concrete construction method combining the skipping method and prestressing technology according to claim 1, characterized in that: In the step 2, the post-cast prestressed tendons are placed throughout the entire length of part or all of the post-casting bins; Furthermore, there is an intermediate step 1 between step 7 and step 8: when the concrete in the post-casting bin enters the shrinkage stage, the two ends of the post-casting prestressed tendons placed throughout the length of the post-casting bin are constrained.
4. A mass concrete construction method combining the skipping method and prestressing technology according to any one of claims 1 to 3, characterized in that: A construction joint is arranged between any adjacent first pouring bin and the second pouring bin.
5. A mass concrete construction method combining the skipping bin method and prestressing technology according to claim 4, characterized in that: There is an intermediate step 2 between step 1 and step 2: arranging support frames at the periphery of the construction area and in the construction joint.
6. A mass concrete construction method combining the skipping method and prestressing technology according to claim 5, characterized in that: The support frame is provided with transverse frame ribs and vertical frame ribs; A plurality of transverse structural reinforcements are arranged along the periphery of the construction area and the extension direction of the construction joint; the transverse structural reinforcements are welded and connected at the intersection, and the vertical structural reinforcements are buried underground from the intersection.
7. A mass concrete construction method combining the skipping method and prestressing technology according to any one of claims 5 to 6, characterized in that: In step 2 and step 6, the implementation method of constraining the two ends of the prestressed tendons is that the two ends of the prestressed tendons are welded to the support frame.
8. The method for mass concrete construction combining the skipping method and prestressing technology according to claim 4 is characterized in that: In step 8, the closed construction is implemented by pouring concrete into the construction joint and curing it.
9. The method for mass concrete construction combining the skipping method and prestressing technology according to claim 1 is characterized in that: In step 2, the arrangement direction of the prestressed tendons is parallel or perpendicular to the edge of the first casting bin or the second casting bin.
10. The method for mass concrete construction combining the skipping method and prestressing technology according to claim 1, characterized in that: The strength of the mass concrete that can be used for tensioning construction is not less than 75% of the designed strength.