강관 및 PHC 매입말뚝의 최적화에 따른 교량기초의 공사비 비교

In this study, execution costs of the foundation system are compared with PHC and steel pile in the same soil layers and load condition. Steel piles installed on the thin weathered rock are reduced as 12.5% in comparison with the number of PHC piles. Steel piles installed on the soft rock through weathered rock with 1.7m of thickness reduce the number of piles as 35.7% (STK 400) and 46.4% (STK 490), respectively, in comparison with PHC piles installed on the weathered rock. Also, they reduce the number of piles as 26.5% (STK 400) and 38.8% (STK 490), respectively, in comparison with steel piles (STK 400) installed on the weathered rock. When the thickness of footings is constant, steel piles installed on the soft rock may reduce the area of footings up to 12.2% (STK 400) and 45.4% (STK 490), respectively, in comparison with PHC piles installed on the weathered rock. Total cost of foundation system installed on the soft rock with steel piles (STK 400) increases as 12%, whereas in case of replaced with steel piles (STK 490), it reduces as 16% in comparison with PHC piles installed on the weathered rock. This is because the cost reduction due to the number of piles and footing area is more effective despite high cost of steel piles (STK 490). When the thickness of weathered rock is less than 5m, installing steel piles (STK 490) on the soft rock through it is more economic in comparison with installing PHC piles on the weathered rock.