Probability Density Distribution and Reliability Evaluation of Load Settlement Curve of PHC Pile in Deep Silt Area

PHC pile has become one of the widely used foundation treatment methods in soft soil foundation. Taking a pile foundation project in Wenzhou as an example, the thickness of hydraulic fill and silt in the site is 27.20–33.60 m, and the length of PHC pile is mostly 43–50 m. In this paper, the load test results of 130 PHC compression piles detection in the project site are statistically analyzed by the method of probability regression parameters. The results show that the settlement value under all levels of load basically conforms to the normal distribution, and the goodness of fit is 0.80–0.90; The exponential, hyperbolic and power function are used for fitting, and the regression coefficient is statistically analyzed. The normal distribution function is used for fitting, and the goodness of fit is 0.85–0.99; On this basis, the relationship between the safety factor and reliability index of the ultimate bearing capacity of the PHC pile and the allowable settlement is analyzed. With the increase of the allowable settlement, the ultimate bearing capacity of the PHC pile increases, and the corresponding safety factor and reliability index increase. Among the three fitting curves, the reliability index calculated by the exponential function is the largest, and the reliability index is close to that of power function and hyperbolic function.