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http://dx.doi.org/10.7843/kgs.2021.37.11.37

Evaluation of the Installation Mechanism of the Micropile with the Base Expansion Structure Using a Centrifuge Model Test  

Kim, Jae-Hyun (Dept. of Civil Engrg., The College of Art, Culture and Engrg., Kangwon National Univ.)
Kim, Seok-Jung (Planning and Coordination Dept., Korea Institute of Civil Engrg. and Building Technology)
Han, Jin-Tae (Dept. of Geotechnical Engineering Research, Korea Institute of Civil Engrg. and Building Technology)
Lee, Seokhyung (Dept. of Geotechnical Engineering Research, Korea Institute of Civil Engrg. and Building Technology)
Publication Information
Journal of the Korean Geotechnical Society / v.37, no.11, 2021 , pp. 37-49 More about this Journal
Abstract
Micropiles are widely used in construction field to enhance bearing capacity and reduce settlement of existing foundation. It has various benefits such as low construction expense, simple installation process, and small construction equipment. Recently, new microple equipped with the base expansion structure at the end has been developed to improve the foundation bearing capacity. The improvement of load capacity can be conceptually achieved by expanding the base expansion structure when a load is applied to the micropile. However, the expansion mechanism of the base expansion structure and the improvement of load capacity of the micropile were not yet experimentally validated. Therefore, in this study, a series of centrifuge model tests was performed to evaluate the effect of the base expansion structure on the improvement of load capacity. Two types of soil, sand and weathered rock, were prepared and the loading tests were performed using the real micropile with the base expansion structure. During the tests, the earth pressures surrounding the base expansion structure were monitored. As a result, when a load of 30 kN was applied to the micropile, the increase in the ratio of the horizontal to vertical pressure increment (∆σh/∆σ𝜈) ranged from 0.4 to 0.58 in sand and ∆σh/∆σ𝜈 = 0.19 in weathered rock, respectively. Therefore, it can be concluded that the increase in the horizontal earth pressure adjacent to the base expansion structure will improve the bearing capacity of the micropile.
Keywords
Base expansion type micropile; Bearing capacity; Centrifuge test; Sand; Weathered rock;
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