Influence of the spatial distribution of soil strength on the bearing capacity of single pile

The soil parameters may obey different types of distribution. However, the lognormal distribution is generally chosen in the probability analysis of pile foundations. The undrained strength of soil is taken as the random variable, and it is assumed to obey Lognormal distribution, Beta distribution and Gamma distribution, respectively. Then the bearing behavior of single pile foundation under vertical and horizontal loads is simulated by stochastic finite element method, in which the different coefficient of variation and correlation distance are considered. The mean value and standard deviation of bearing capacity of single pile are analyzed. The results show that the average vertical bearing capacity of single pile is not affected by the distribution of soil strength. The average horizontal bearing capacity of single pile is the largest when the lognormal distribution is adopted, while the bearing capacity is the smallest when random field obeys the Beta distribution. The standard deviation of bearing capacity obtained by Beta distribution under vertical and horizontal loads is the largest. It is recommended to use Beta distribution to determine the bearing capacity of single pile foundation when the spatial distribution of soil strength is unknown.