A rapid construction method for concrete dams in severe cold areas to prevent cracks

Abstract

The invention discloses a severe cold area concrete dam rapid construction method capable of preventing cracks. Upstream side foam concrete is poured on the upstream side of dam body concrete; an upstream side temporary formwork is arranged between the upstream side foam concrete and the dam body concrete; an upstream side main formwork is arranged on the outer side of the upstream side foam concrete; polyurea is applied to the surface layer of the upstream side foam concrete after the upstream side foam concrete reaches an age and the upstream side main formwork is dismounted ; downstream side foam concrete is poured on the downstream side of a dam body, a downstream side temporary formwork is arranged between the downstream side foam concrete and the dam body concrete; a downstream side main formwork is arranged on the outer side of the downstream side foam concrete; and mortar is applied to the surface layer of the downstream side foam concrete after the downstream side foam concrete reaches an age and the downstream side main formwork is dismounted. The severe cold area concrete dam rapid construction method capable of preventing the cracks has the advantages that the implementation cost is low, the engineering progress is fast, operation is simple, the safety is guaranteed, and the post-maintenance is simple.

Description

technical field [0001] The invention relates to a construction method of a concrete dam, in particular to a rapid construction method of a concrete dam in a severe cold area for preventing cracks. Background technique [0002] Concrete dams are bulky, and during the hardening process of the concrete, the heat generated by the hydration of the cement leads to changes in strain and stress in the block, and the dam body often produces harmful cracks. Concrete cracks are the result of a combination of factors, including temperature changes, concrete volume shrinkage, dehydration drying shrinkage, and other shrinkage deformations related to concrete volume deformation. Among them, the temperature change plays a leading role. Most of the early shrinkage cracks produced by hydraulic dam concrete are surface cracks, and some of them will develop into deep cracks or penetrating cracks. The cracks on the concrete surface of the dam are mainly due to the temperature difference and hu...

AI Technical Summary

Problems solved by technology

[0004] Upstream dam surface treatment—painting interface agent—spraying polyurea—spraying polyurethane foam—polyurethane surface treatment—painting anti-aging paint, the construction of the design plan needs to go through 6 procedures, and the construction is cumbersome

[0005] (2) The construction is difficult

[0014] 3) Low bond strength between polyurethane and polyurea

[0018] 4) Polyurethane foam flammability

[0019] Polyurethane has a low ignition point of 260° to 280°, poor fire resistance, and the sparks splashed when encountering an open flame or welding are flammable and highly toxic after burning.

[0020] 5) Poor durability of polyurethane foam

At the same time, the formed chromophore causes the color of the product to become darker. When used in engineering, if no color or external protection is used, the color will change from yellow to dark brown, which will affect the overall appearance

[0022] 6) The aging property of polyurethane foam

[0024] During the construction process, the dam body is cooled by cooling water pipes, generally with a row spacing of 1.5 to 2.0m, arranged in layers on the surface of the dam construction warehouse, the process is complicated, and it greatly interferes with the rapid construction of the dam body; Consolidation grouting is carried out on the dam body If the cooling water pipe is punctured, it will affect the water flow effect and the grouting effect of the dam body; if the temperature control of the cooling water is not appropriate, it may cause artificial cold shock, causing cracks in the dam body concrete; cooling water preparation system, water flow system equipment Large investment, long water supply time, first-stage water supply, second-stage water supply, and even some projects require third-stage water supply for cooling, which is time-consuming, labor-intensive, and expensive; the cooling water supply pipe and outlet pipe are located on the dam body The downstream dam surface interferes with the construction of the formwork of the dam body and affects the construction progress

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