Abstract
Make crackled mortar test block to simulate jointed rock mass reinforced by anchor bars. Computational model of corrosion penetration at different load times can be obtained by corrosion acceleration through electrochemistry. Through observation of anchor bar after corrosion, it is found that primary corrosion is mainly pitting; however, with the development of corrosion, corrosion moves along etch pit to the upper and lower surfaces so as to form partial corrosion. Meanwhile, computational formula of pitting ratio is put forward on the basis of mass loss rate. It is found that, through the pulling out experiment of anchor bar corrosion, corrosion has remarkable influence on anchoring performance of anchor bar; meanwhile, different pitting ratios have different influences on trends of ultimate bond strength, for example, when pitting ratio is bigger (between 9% and 30%), the biggest decreasing rate of bond strength is obviously lower than that under lower pitting ratio (from 1.5% to 5%). According to linear fitting of experimental data, the relationship curve of K, ultimate bond strength ratio, and pitting ratio can be obtained so as to provide basis for judgement of anchoring performance loss in practical engineering.
Highlights
As a key part of underground engineering structure, anchorage structure has become the preferred method for underground engineering reinforcement due to its low cost, fast construction, and small occupied space
Apostolopoulos and Papadakis carried out accelerated corrosion tests on steel bars, and the corrosion results were in good agreement with the corrosion performance of steel bars in practical engineering [8]
In equation (5), δ is the pitting corrosion rate, me is the mass of overflow rust products, and mc is the original mass of anchor bars at pits. done using mc ρπr2b
Summary
As a key part of underground engineering structure, anchorage structure has become the preferred method for underground engineering reinforcement due to its low cost, fast construction, and small occupied space. There is some progress in the research on the degradation of bond properties caused by steel bar corrosion, but there are few studies on the corrosion damage of intermittent joints and anchored rock mass, and most of the existing studies are based on the analysis of uniform corrosion. E relationship curve between the ultimate bond strength coefficient and pitting corrosion rate is fitted, and the variation law of anchoring performance and pitting corrosion rate of jointed rock mass is determined. It has important guiding significance for analyzing the safety and durability of anchoring structure in jointed rock mass tunnel
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