Optimum design method of jacked piles based on interval re-pressed test

The Change in pile capacity with time after installation which is usually referred to time effect or set-up, and the decrease in pile capacity with is termed as relaxation are rarely incorporated in the present design method. The singular ultimate-bearing capacity can be confirmed when the completed piles are repressed at specified time by the convenient pile jacking machine, which is named as the method of interval re-pressed tests and it is different from the traditional re-pressed construction draft. Based on the collected data from Zhuhai and Taiyuan, pile set-up is significant and continues to develop for a long time. The Skov and Denver's equation is adopted to predict the change trend of axial pile capacity with time, and the reliability of this method is testified and the range of A value is confirmed by the results of interval re-pressed tests. The characteristics of predicted set-up capacity are described by the interval re-pressed test results in short term after the initial installation, which is incorporated into the design to optimize the proposal. Meanwhile the accuracy of the method is improved by employing dimensionless setup factor and safety factor. High feasibility of the design process is presented and proved by the design case in Taiyuan. The proposed design method is meaningful to reducing the construction difficulty, decreasing the construction period, saving the cost and improving the reliability of design.