Reliability Analysis of TAMU-POST a Tool for Analysis of Vehicle Impact on In-Line Pile Group

摘要

Soil embedded in-line piles are commonly used to redirect errant vehicles. The impact response of the soil embedded piles is governed by a number of factors including pile embedment depth, pile spacing, pile strength and stiffness, soil strength and stiffness, mass and velocity of the truck. The authors have developed a general and simple analysis-design tool called TAMU-POST to predict the response of a group of in-line piles tied together by a cross beam, impacted by a truck of a given mass at a given approach velocity. The model parameters were determined using experimental data and numerical simulation results. However, there are inherent uncertainties associated with the input parameters including heterogeneity of the soil deposit as well as the simplifications made in the development of the model. Considering widely different impact scenarios, there is no single safety factor that can be applied to all the impact cases. Thus, a Monte Carlo Simulation method was applied with the TAMU-POST code to evaluate the probability of failure of a pile group under a given vehicular impact. The Monte Carlo simulation addresses the uncertainties associated with both the input parameters and the model coefficients. With emphasis of the model on the barrier maximum deflection according to the standard ASTM F2656-07 (which enforces the vehicle flatbed not to penetrate the barrier more than one meter), it was defined that the failure occurs when the dynamic penetration of the vehicle would exceed 1 m. Given adequate ranges for the coefficients of variation for the input parameters, several examples for probabilistic treatment of the problem were presented, so that the probability of failure can be calculated.