Evaluation of Compression Behavior for Barrette Piles

• Main Authors: Ting-Chang Chu, 朱亭昌
• Other Authors: Yit-Jin Chen
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/75718790384004919469

碩士 === 中原大學 === 土木工程研究所 === 100 === ABSTRACT This study collected 40 load tests for barrette piles to evaluate the axial compression behavior. A wide variety of compression load test data are used and these data are divided into drained and undrained databases. These selected criteria represent a wide distribution of interpreted results from the lower, middle, and higher bounds. In addition, these criteria employ varied interpretation bases. The interrelationship and reliability of each interpretation model were established. The interpretation results were used to examine the analysis models of tip and side resistances. For interpretation criteria, L1 occurs at about 0.27%B (B = shaft diameter) with mean displacement of 4.7 mm in drained soils, while L1 occurs at about 0.26%B with mean displacement of 4.2 mm in undrained soils. The results indicate that the initial linear region is in a very small displacement. In drained soils, the ratios of representative interpretation criteria, which are all compared to L2, range from 0.79 to 1.39. The displacements of these criteria locate at between 19.1 and 85.8 mm, and the Chin method is greater than 103.8 mm. In undrained soils, the ratios of representative interpretation criteria, which are all compared to L2, range from 0.75 to 1.4. The displacements of these criteria locate at between 23.4 and 109.6 mm, and the Chin method is greater than 118.8 mm. Among these criteria, the Chin method is upper bound, DIN 4026 method is lower bound, and Hirany and Kulhawy (L2) method is in the reasonable middle range. For axial capacity, the mean ratio of measured tip resistance to predicted tip resistance is between 0.11 and 0.22, while the mean ratio of measured side resistance to predicted side resistance is about 1.32-1.46 in drained soils. The mean ratio of measured tip resistance to predicted tip resistance is 0.63, while the mean ratio of measured side resistance to predicted side resistance is about 0.93-0.95 in undrained soils. This indicates that the bearing capacity theory to evaluate tip resistance is overestimated for both drained and undrained soils. For side resistance, the analysis model is underestimated for drained soils, but it is consistent in undrained soil. Based on the results of back-calculation analysis, the suggested values of K/Ko are 1.07 and 0.74 for drained soils and undrained soils, respectively.