This study aims to investigate on static behavior of guardrail supporting piles subjected to lateral load using three-dimensional finite element analysis. The numerical model was verified by a field static load test. Then a parametric study was carried out and the parameters include slope angle, pile location from slope edge, and pile rigidity. The yield bearing capacity and its corresponding soil reaction force distribution for all cases were discussed and compared with the previous study.
Guardrails barriers are a typical safety system preventing vehicles from running out of roadway and/or falling into the slope at the roadside. The guardrail generally consists of a protection cross-beam and supporting in-line piles (Wu and Thomson, 2007; Sassi, 2011; Pajourh et al., 2017). The guardrail piles are generally installed in vicinity of the slope edge of the embankment because the roadside area is very limited. In Korea, the design of these piles including the barrier system practically solely relies on engineer's previous experience and numerical analysis. The final design is afterward validated with a full-scale car-crash test carried out in a certified testing site. Then, the final design of the pile as well as the barrier system are constructed and inspected by a field static test to check whether the piles would meet the criterion. The criterion is that the static bearing capacity of the pile should meet 90% of dynamic bearing capacity measured by the carcollision test. This static load test at the construction site is performed for every sample pile selected from in-lined piles at every 1 km (MOLITK, 2016). Among these procedures, any geotechnical consideration is not involved. Moreover, the behavior of piles installed for the support of guardrail system has not been well understood.
In this study, the static capacity of guardrail supporting piles subjected to lateral load was investigated to improve the current design practice using three-dimensional finite element analysis. The lateral capacity of piles is generally estimated by semi-theoretical methods. These methods assume a form of lateral soil pressure distribution along the length of the pile. This lateral soil pressure distribution has been updated by analytical and/or experimental studies (Brinch Hansen, 1961; Broms, 1964; Petrasovits and Award, 1972; Chari and Meyerhof, 1983; Prasad and Chari, 1999). Thus, this soil reaction pressure approach can be also used to the static capacity evaluation of the guardrail supporting piles.
