Abstract
This study investigated the corrosion damage and bearing characteristics of bridge pile foundations under a dry-wet-freeze-thaw cycle of composite salt in an alpine salt marsh area using an in situ test, laboratory test, and numerical simulations. The in situ test showed that the dry-wet-freeze-thaw cycle has little effect on the quality of the concrete specimens and rebar. The area of the rebar at a depth of 0.25 m had the highest corrosion rate of 91%. The application of epoxy resin on the surface improved erosion resistance. After one year of outdoor dry-wet-freeze-thaw cycle test, due to the interaction of compound salts, the quality of specimens is reduced under the denudation of chloride ions, while the mass of specimens is increased by the corrosion products formed under the joint action of carbonate and sulfate, resulting in less obvious change of specimen quality, the antierosion coefficient of the specimens decreased, the maximum loss rate of compressive strength was 38.2%, and the pile foundation began to deteriorate. The laboratory test showed that expansive substances, such as Friedel salt, appeared in the concrete specimens of pile foundation during 225 cycles of dry-wet-freeze-thaw cycles, the relative dynamic elastic modulus was reduced by 60.9%, the antierosion coefficient was reduced to 0.51, and the compressive strength loss rate was 65.9%. As such, the pile foundation was seriously damaged. The numerical simulation shows that, with an increase of the peeling thickness and the corrosion depth, the bearing capacity of the pile foundation will gradually decrease after 8 years. Without maintenance, the bearing capacity of a pile foundation will decrease by 34.45% in the 20th year.
Highlights
With the promotion of the Western Development Strategy in China, “development driven by traffic” has become an important part of construction in Qinghai Province
Predecessors used different methods such as the in situ test, laboratory test, and numerical simulations to study the mechanical properties of bridge pile foundations under dry-wet or freeze-thaw cycles, but the research methods and research environmental conditions are relatively simple, and few people use these three methods to study the bearing characteristics and corrosion damage of pile foundation under the dry-wet-freezethaw cycles
(2) Antierosion Coefficient. e antierosion coefficient is used to describe the degree of corrosion resistance of the specimen, and it is calculated as follows: Kc where Kc is the antierosion coefficient of the specimen; Rc is the compressive strength of specimen immersed in erosion solution, MPa; and Rs is the compressive strength of specimens immersed in water at the same age, MPa
Summary
With the promotion of the Western Development Strategy in China, “development driven by traffic” has become an important part of construction in Qinghai Province. Pilehvar et al [8,9,10,11] studied the mechanical properties and durability of pile foundation concrete after replacing cement with fly ash under the conditions of freeze-thaw cycles in laboratory model tests. Predecessors used different methods such as the in situ test, laboratory test, and numerical simulations to study the mechanical properties of bridge pile foundations under dry-wet or freeze-thaw cycles, but the research methods and research environmental conditions are relatively simple, and few people use these three methods to study the bearing characteristics and corrosion damage of pile foundation under the dry-wet-freezethaw cycles. Many researchers have studied the mechanical properties of pile foundations under special conditions such as cohesive soil, loess, expansive soil, weak interlayers, and earthquakes, but few have studied the bearing characteristics and corrosion damage of pile foundation in the special environment of alpine salt marsh area.
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