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CN-122013778-A - Large-volume beam concrete pouring construction method

CN122013778ACN 122013778 ACN122013778 ACN 122013778ACN-122013778-A

Abstract

The invention relates to the technical field of water transportation engineering and discloses a large-volume beam concrete pouring construction method which comprises the following steps of S1, prefabricating a partition type active temperature control integrated jig frame, S2, precooling and pouring, S3, dynamically heating field gradient management, S4, demoulding, and transferring the partition type active temperature control integrated jig frame after concrete meets demoulding conditions, wherein the partition type active temperature control integrated jig frame is longitudinally divided into at least three independent temperature control loop areas by the prefabricated partition type active temperature control integrated jig frame, the central temperature control center is started for precooling the partition type active temperature control integrated jig frame, and the A area, the B area and the C area of the integrated jig frame are controlled by the central temperature control center after concrete pouring is completed. Through the partition regulation and control mechanism, the tensile stress concentration of the constraint end region is effectively inhibited, the problem of constraint cracks caused by longitudinal temperature gradient is solved, and the one-time integral pouring of concrete is realized.

Inventors

  • YAO CHUANCHAO
  • LIU WEI
  • YANG SHANJUN
  • WANG LIANG
  • Diao Wenhan
  • ZHOU LONG
  • HUANG JIE
  • WU LEI

Assignees

  • 中交第二航务工程局有限公司
  • 中交二航局第三工程有限公司

Dates

Publication Date
20260512
Application Date
20260410

Claims (10)

  1. 1. The large-volume beam concrete pouring construction method is characterized by comprising the following steps of; s1, a preparation stage, namely prefabricating a partitioned active temperature control integrated jig frame, wherein the integrated jig frame is longitudinally divided into at least three independent temperature control loop areas along a cross beam, and comprises a cross-center area A, two constraint end area B and two constraint end areas C, and the partitioned active temperature control integrated jig frame is hoisted and fixed and connected to a central temperature control center; s2, starting the central temperature control center, pre-cooling the partitioned active temperature control integrated jig frame to enable the surface temperature of a bottom die to be reduced to 15-20 ℃, and integrally pouring mass concrete into the partitioned active temperature control integrated jig frame; s3, after the concrete pouring is finished, controlling the A area, the B area and the C area of the integrated jig frame through the central temperature control center, and executing the following temperature control steps: the peak heat is led out, namely, a cooling medium of 5-10 ℃ is pumped into all temperature control loop areas within 0-24 hours after pouring, and strong cooling is carried out; The gradient stress regulation and control, namely, the zone A, the zone B and the zone C are regulated and controlled in a zonal way within 24-72 hours after pouring, and the temperature difference between the concrete core and the surface of the bottom die is kept at 20-25 ℃ and below by sensor data feedback, and the longitudinal temperature difference between the core of the zone A and the cores of the zone B and the core of the zone C is kept at 5-8 ℃ and below; controlling the partition type active temperature control integrated jig frame to guide the concrete structure to be cooled integrally within 72-120 hours after pouring, wherein the integral cooling rate is controlled to be 0.3-0.5 ℃ per hour or below; And S4, demoulding, namely after the concrete meets demoulding conditions, demoulding and transferring the whole partitioned active temperature control integrated jig frame.
  2. 2. The method for pouring and constructing the large-volume beam concrete according to claim 1, wherein the large-volume concrete in the step S2 is C50 grade low hydration heat concrete, the cementing material of the large-volume beam concrete is composed of 350-400kg/m 3 P.LH42.5 low hydration heat silicate cement and F class I fly ash accounting for 15-25% of the total amount of the cementing material, and the water-cement ratio is controlled to be 0.32-0.38.
  3. 3. The method for pouring and constructing the large-volume beam concrete according to claim 1, wherein the cooling medium used in the step S3 is a composite water-based anti-corrosion cooling liquid, and the components comprise, by mass, 25-40% of ethylene glycol, 0.1-0.3% of benzotriazole, 0.2-0.5% of sodium molybdate and the balance of deionized water.
  4. 4. The method according to claim 1, wherein the step S1 includes arranging Pt100 platinum resistance temperature sensors at a geometric center in the beam reinforcement cage, 50-100mm from the top surface of the bottom mold, and 50-100mm from the top surface, and connecting signals of the sensors to the central temperature control center for providing data feedback of the sensors.
  5. 5. The large-volume beam concrete pouring construction method according to claim 1, wherein the specific operation of zone regulation in the step S3 is that the central temperature control center maintains the inlet temperature of the cooling medium in the area A at 10-18 ℃, and the flow of the cooling medium in the area B and the cooling medium in the area C are dynamically regulated or the inlet temperature of the cooling medium in the area C is increased to 15-22 ℃ so as to actively reduce the cooling rate of the area B and the cooling rate of the area C, thereby realizing the control of the longitudinal temperature difference.
  6. 6. The method for casting the concrete of the large-volume beam according to claim 1, wherein in the step S2, the casting temperature of the large-volume concrete is controlled to be in a range of 25-30 ℃, and continuous casting is performed in a stepped pushing mode with a layering thickness of 300-500 mm.
  7. 7. The method for casting large-volume beam concrete according to claim 1, wherein the main body of the partition type active temperature control integrated jig in the step S1 is a pipe truss structure, a bearing main pipe truss is a seamless steel pipe, and a hollow cavity of the seamless steel pipe is a cooling medium channel of the temperature control loop region.
  8. 8. The method for casting large-volume beam concrete according to claim 1, wherein the demoulding conditions in the step S4 include: The strength of the concrete curing test block under the same condition reaches 75-85% of the design strength; the difference between the core temperature of the concrete and the daily average temperature of the construction site environment is reduced to 15-20 ℃ or below.
  9. 9. The method for pouring and constructing the large-volume beam concrete according to claim 1, wherein in the step S4, after demoulding, the surface of the beam is covered with a plastic film and geotextile, and water sprinkling and moisture conservation are carried out for at least 14-21 days.
  10. 10. The method for pouring concrete on a large-volume beam according to claim 9, wherein the maintenance comprises performing anti-corrosion construction on the surface of the beam, and rolling or spraying with epoxy-based anti-corrosion paint to achieve a total dry film thickness of 400-500 μm.

Description

Large-volume beam concrete pouring construction method Technical Field The invention relates to the technical field of water transport engineering, in particular to a large-volume beam concrete pouring construction method. Background In large-scale harbor and dock projects, large-volume concrete structures, such as dock beams, large-scale platforms, panels and the like, are key bearing parts constituting a dock body. Because of the huge concrete volume, a large amount of heat is released in the hydration process of the cement in the concrete, so that the temperature in the structure is increased sharply. If not controlled, significant temperature gradients can form between the concrete core and the surface, and between different parts of the structure, thereby creating temperature stresses that exceed the early tensile strength of the concrete, resulting in cracking of the structure. Particularly in the marine chloride corrosion environment, the temperature cracks can become rapid channels for invasion of harmful ions, and the safety and long-term durability of the structure are seriously affected. The prior art generally starts from both materials and processes. For example, low-heat cement or admixture such as fly ash is adopted to reduce the total hydration heat, or cooling water pipes are pre-embedded in the concrete, and spraying or covering maintenance is carried out on the surface of the concrete to lead out heat and reduce the temperature difference between the inside and the outside. However, these conventional measures have significant limitations. The existing temperature control means are mainly focused on controlling the temperature difference between the concrete core and the surface, and for long-strip-shaped structures such as a cross beam, the temperature gradient along the longitudinal direction is often ignored. The unconstrained region (such as midspan) and constrained region (such as the junction with large pile cap or poured structure section) of the beam can form significant longitudinal temperature difference due to the difference of heat dissipation conditions and constraint states, and thus, huge tensile stress is generated at the constrained end, which is the main cause of longitudinal or oblique cracks of the structure, but the prior art lacks effective control means for the problems. The prior art adopts a layered pouring method, but not only prolongs the construction period, but also easily forms a construction cold joint between layers, and becomes a weak link of structural durability. The scheme of embedding cooling water pipes inside is complex in arrangement, the disposable consumption cost of the pipes is high, interference with dense reinforcing steel bars is likely to occur, and construction quality is affected. Meanwhile, the external spray cooling mode is low in efficiency, and if seawater or ordinary water is directly used for cooling in a salt fog environment of wharf construction, corrosion to a metal template and a temperature control pipeline system can be additionally prepared, so that the stability and reliability of a temperature control effect are affected. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a large-volume beam concrete pouring construction method, which solves the problem that the restraint end is easy to generate temperature cracks due to insufficient longitudinal temperature gradient control of the large-volume beam in the prior art. The invention aims to realize the technical scheme that the large-volume beam concrete pouring construction method comprises the following steps of; s1, a preparation stage, namely prefabricating a partitioned active temperature control integrated jig frame, wherein the integrated jig frame is longitudinally divided into at least three independent temperature control loop areas along a cross beam, and comprises a cross-center area A, two constraint end area B and two constraint end areas C, and the partitioned active temperature control integrated jig frame is hoisted and fixed and connected to a central temperature control center; s2, starting the central temperature control center, pre-cooling the partitioned active temperature control integrated jig frame to enable the surface temperature of a bottom die to be reduced to 15-20 ℃, and integrally pouring mass concrete into the partitioned active temperature control integrated jig frame; s3, after the concrete pouring is finished, controlling the A area, the B area and the C area of the integrated jig frame through the central temperature control center, and executing the following temperature control steps: the peak heat is led out, namely, a cooling medium of 5-10 ℃ is pumped into all temperature control loop areas within 0-24 hours after pouring, and strong cooling is carried out; The gradient stress regulation and control, namely, the zone A, the zone B and the zone C are regulated and controlled in a zonal way within 24-7