An Elemental Study for construction elevation of a Underground Columns in Top-Down construction Method

TOP-DOWN공법에 의한 지하기둥의 시공성 향상을 위한 기초적 연구

This study is about accurate steel column position method in the Top down method's delicate part. When the concrete is placing, it is required that complementary measures to the transformation due to concrete pressure, column buckling, the trouble due to bar net inserting and so on. To solve the problem of exist method, the concrete is placed at the bottom of excavated hole in advance. then, the steel column is inserted into the excavated hole. With a new method try, the problem due to placing pressure and others is could be prevented. In this study, the concrete is examined with test-slump, slump flow, and compressive strength to do quantitative analysis of concrete. The factors of the experiment is plasticizer, retarder addition rate, fly ash substitution rate to cement. Considering of the new method try, the retarder added concrete properties-fluidity, viscosity, strength-is investigated as time lapsing.