현장재하시험을 통한 고강도 강관말뚝 거동

Abstract

Recently, high strength steel pipe piles have been increasingly used. However, the analyses on the axial behavior of these piles measured from the static and dynamic tests are limited. In this thesis, 11 pile load test data, measured from the static and dynamic pile load tests, were analyzed. Based on the yield load criterion and the settlement criterion, the ultimate loads were predicted for the piles driven to the multi-layered soil consisting of sand and clay. In order to check validity of bearing capacity equations that are commonly used, the estimated ultimate loads were normalized to the measured ones. The applicability of factor of safety used in allowable bearing capacity equations were evaluated. Also, pile setup and drivability of high strength steel pipe piles were investigated. Based on the dynamic pile load tests, allowable bearing capacity was found to increase with an increase in impact energy. Also a regression equation was developed to estimate the bearing capaicity using the final penetration length. Pile capacities measured from dynamic pile load tests were compared to those measured from the static pile load tests. Pile capacities measured at restrikes increased compared to those measured at end of initial driving, indicating pile setup. The pile capacities measured from dynamic pile load tests are comparable to the ones measured from the static pile load tests. The capacities estimated from the static bearing capacity formula are comparable with the capacities measured from the static load tests. In addition, the static bearing capacity formular and Meyerhof's formula underestimated the bearing capacities about 1.66 times lower than the measured ones. This indicates that the factor of safety lower than 3.0 can be applied for calculation of allowable bearing capacity. The Chin's method among the ultimate load criteria predicted the closest ultimate capacities. The P-S method among the yield load criteria estimated the closest ultimate capacities. The Tomlinson's (0.1D) method among the net settlement criteria predicted the closest ultimate capacities. This study is based on 11 static and dynamic pile load test data. The results of this study will be very useful for understanding behavior of high strength steel pipe piles driven into the similar soil conditions.