• Geotechnical Engineering
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• v.12 no.4
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• pp.33-46
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• 1996

When structures are constructed in ground with poor bearing capacity, deformation of ground may induce foundation settlements and cracks of structures. Recently, high pressure jet grouting is widely used to improve the engineering properties of such foundation. Sometimes, the grouting columns are built in the ground by jet grouting method. They are used as in -situ piles to increase the bearing capacity of existing foundation. In this paper, as for the grouting columns built in ground by high pressure jet grouting with double tube rod, the effects on reinforcement and bearing capacity of ground are investigated. A series of laboratory tests has been performed on the specimens sampled from the grouting columns and a pile load test has been performed on a grouting column. The test results show that high pressure jet grouting has a sufficient effect on reinforcement of ground and restraint of settlement of structure.

• Land and Housing Review
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• v.8 no.4
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• pp.233-247
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• 2017

In Europe and the USA, the use of limit state design method has been established, and the Korea Ministry of Land, Transport and Maritime Affairs has implemented the bridge substructure design standard based on the critical state. But Korean piling methods and ground conditions are different from Europe and USA, the limit state design method can not be used immediately. In this study, the resistance coefficient was proposed by comparing and analyzing the results of the static load test(9 times) and dynamic load tests(9 times of EOID and 9 times of Restrike) with the bearing capacity calculated by Meyerhof(LH design standard, Road bridge design standard) method and surcharge load method(using Terzaghi's bearing capacity coefficient and Hansen & Vesic's bearing capacity coefficient). The previous LHI study showed the resistance coefficient of the LH design standard was 0.36 ~ 0.44, and this research result showed the resistance coefficient was 0.39 ~ 0.48 which is about 8% higher than the previous study. In this study, we tried to obtain the resistance coefficient mainly from the static load test and the resistance coefficient was 0.57 ~ 0.69(Meyhof method : LH design standard) based on the ultimate bearing capacity and the resistance coefficient was 0.49 ~ 0.60(Meyhof method : LH design standard) based on the Davissons bearing capacity. The difference of the resistance coefficient between the static and dynamic load test was greater than that we expected, we proposed the resistance coefficient(0.52 ~ 0.62 : Meyerhof method: LH design standard) using the modified bearing capacity of the dynamic load test. Summarizing the result, the coefficient of resistance obtained from the static and dynamic load tests was 0.35 ~ 0.76, which is greater than 0.3 suggested by the Road bridge design standard, so the economical design might be possible using the coefficient of resistance proposed by this study.