A probabilistic approach to estimation of the ultimate load of end-bearing piles on settlement criterion

Pile foundation is one of the most common types of foundations in the presence of soft soils. The safety of the entire structure depends on the pile foundation safety. Stochastic (probabilistic) modeling of load-bearing elements is a modern trend in the quantitative structural safety assessment. The article describes the probabilistic approach to estimate the bearing capacity (ultimate load) of end-bearing piles on settlement criterion. Design load and elastic modulus of a pile material are the main stochastic (random) parameters that determine the probability of end-bearing pile failure. The graphical model of failure and safety areas is proposed, on the basis of which conclusions can be drawn about the allowable load during the design and inspection of pile foundations. The numerical example shows that the method of pile reliability analysis based on FOSM (First Order Second Moment) gives similar results as the method on the basis on FORM (First Order Reliability Method). Therefore, for an accurate evaluation of the reliability index (according to the considered mathematical model), the first iteration of the FORM method is sufficient. Experimental modeling of pile behavior showed good convergence of the theoretical result with the experimental result based on the Monte Carlo method. For a comprehensive reliability analysis of end-bearing piles, it is necessary to consider a pile as a system (in terms of reliability theory).