Reliability of Laterally Loaded Rigid Piles

Due to modernisation of main railway tracks in Poland there was a need to change the existing overhead electrical transmission lines together with their supports and foundations of the supports. One of possible way to construct a new foundation of such support is the direct connection of the support with a single pre-cast concrete pile embedded in soil. The piles used are usually short, then in a certain soil conditions have to be treated as rigid piles and the ultimate soil lateral resistance has to be considered. Computations of rigid piles by Brinch Hansen method demonstrates high sensitivity of ultimate lateral loading to precise determination of the rotation centre of the pile under consideration. The position of the centre is affected by some random factors, for example random variability of soil properties and loading applied. due to very complex nature of solution of equilibrium equations in the case of Brinch Hansen method being in use any evaluation of safety measure constitutes rather difficult problem. Two alternative approaches are suggested. one is an algorithm supported by some symbolic computations combined with some power series expansions. The second one bases on the response surface method and can be applied both for cohesive and non cohesive soils. Within the presentation some important numerical aspects will be discussed. Additionally computational examples allow the study a relationship between “classical” safety factor versus reliability index as well as an effect of spatial averaging.