동결온도와 재하속도에 따른 동결토의 일축압축 및 쪼갬인장 강도특성에 관한 실험적 연구

Abstract

Recently the world is suffering from the difficulty in demand and supply of energy due to the democratic movements sweeping across the Middle East. Subsequently, the world is putting the eyes on never-developed extreme places such as polar lands or deep sea where a lot of underground resources are deposited. Especially in Antarctica so-called the last repository of natural resources, 6 billion tons of gas hydrate, called as future energy, was recently discovered by research teams. Moving in line with it, Korea is planning to construct ‘Jangbogo Station’, the second Antarctic research station, different from ‘Sejong Research Station’ that has been concentrating on the research for antarctic lives and fishery resources, at Terra Nova Bay located in the Southeast Antarctica, using cold extremity construction methods with a goal to complete by 2014. However the eternal frost region has completely different construction environments condition such as weather, climate, engineering characteristic of the ground, cultural geography and custom from those of Korea or other regions. Therefore, applying the basic knowledge of normal ground construction methods to the eternally-frozen ground may cause unreasonable results, so more systematic and professional studies of frozen ground are necessary.

This research investigated the strength value and initial elastic modulus value of the eternally-frozen ground through uniaxial compression test and indirect tensile test using frozen artificial soil specimen. For the accuracy of the test results, the sandy-mud mix of standard Jumunjin sand and 20% in weight of kaolinite was used as the specimen of these laboratory tests. The specimen was prepared by varying the water content ratio of 7%, 15% and 20%, then the variation of strength value depending on the water content was observed. This research also established three kinds of environments under freezing temperature of -5℃, -10℃ and -15℃, then observed the variation of strength value depending on the freezing environments. In addition, the tests were divided the loading rate into 6 phases and observed the variation of the stress-strain ratio depending on the loading rates.

The result of test data showed the conclusions that the lower the freezing temperature, the larger the strength value

the faster the load rate the more of influence on the strengths of uniaxial compression and indirect tensile of the frozen specimen and produce the different strength engineering property through initial tangential modulus of elasticity. Finally long-term strength under contain water content ratio and freezing temperatures was checked through producing stress-strain ratio curves depending on the loading rate.

the increase of the ice content in the specimen according to the increase of water content ratio makes influence on determining the strength value of the specimen