International Journal of Ocean System Engineering 2(2) (2012) 92-96 http://dx.doi.org/10.5574/IJOSE.2012.2.2.092 International Journal of Ocean System Engineering Rockfall Impact Analysis of Typical Roadway Using Finite Element Simulation Jinho Woo 1 and Won-Bae Na 1 * 1 Department of Ocean Engineering, Pukyong National University, Busan, Korea (Manuscript Received February 20 2012; Revised March 26, 2012; Accepted May 15, 2012) Abstract This study presents a rockfall impact analysis of a typical roadway. Dynamic finite element analyses using ANSYS AUTODYN are conducted to determine the effect of the drop heights (5 m, 10 m) on the damage to a roadway model. The Rockfall is modeled as a spherical shape with a weight of 400 kg, and each drop height is converted to a corresponding impact velocity to save computational time. The roadway model is comprised of an asphalt layer, base layer, sub-base layer, and sub-grade layer. In this paper, the asphalt is modeled using a linear elastic model. The base layer, sub-base layer, and sub-grade layer are modeled using a Mohr-Coulomb model. From the analyses, the effects of the drop height on the damages and stresses are examined and discussed. Keywords: Impact analysis, Rockfall, Asphalt concrete, Finite element analysis 1. Introduction New roads are continually being built, and existing roads are being expanded. As a result, road cut slopes have been increasing rapidly. Unfortunately, this slope increase causes rockfalls. Rockfalls are a major hazard for roadways. Property losses occur annually as a result of rockfall every year. Therefore, specific engineering problems involve significant impact load- ing such as the rockfall impact on a roadway. Asphalt is widely used as a construction material as well as a common material for pavement of roadway. Many studies have been performed for asphalt. Some of those have focused on the fracture mechanical characterization of asphalt [1-2]. Other studies have focused on the response of asphalt under moving loads of aircraft, trucks or cars [3-4]. However, an impact analysis is also a significant requirement in specific engineering problems such as the rockfall impact on a typical roadway. This paper presents a rockfall impact analysis of a typical roadway. For this presentation, as an initial stage, a transient finite element dynamic analysis is carried out to capture the dynamic response of a roadway. Because the material model is quite signifi- cant for the impact simulation- the asphalt is modeled using a linear elastic model. The base layer, sub-base layer, and sub-grade layer are modeled a Mohr- Coulomb model. In addition, two different drop heights are considered. ANSYS AUTODYN, the general purpose finite element software, is used for explicit dynamic analyses. 2. FEM Simulation 2.1 Rockfall modeling This work employs the explicit finite element method program ANSYS AUTODYN, which uses a Lagrangian formulation. The model consists of two parts: the roadway, and rockfall. An eight-node solid element is used for the model. * Corresponding author. Tel.: +82-51-629-6588, Fax.: +82-51-629-6590, E-mail address: wna@pknu.ac.kr Copyright © KSOE 2012.