Abstract

This paper investigates the effect of fire on the performance of geosynthetic reinforced soil bridge abutments using experimental tests and finite element analyses. Experimental programs were comprised of a series of tensile strength tests at elevated temperatures and fire resistance tests, which were performed on a physical model. Findings revealed the adverse effect of fire on geosynthetic reinforced soil bridge abutments when fire duration exceeded 60 min. Results show that the depth within the backfill affected by the fire is approximately 50 cm.

Introduction

In recent years, the use of the geosynthetic reinforced soil (GRS) technology for bridge abutments has been recommended because it has advantages over conventional methods. The GRS bridge abutment system includes a segmental geosynthetic reinforced soil wall with a bridge seat (sill) placed on the top of it. The stability of these structures depends on the mechanical properties of the reinforcing elements as well as their interactions with the soil. Fig. 1 shows a typical GRS bridge abutment system with modular concrete block facing Geosynthetic reinforcements such as geotextiles and geogrids are made from synthetic polymers and mechanical properties of the polymers change with increased temperatures. Nonlinear increases in creep, a significant reduction in tensile strength, increased failure strain, increased degradation, a reduction in the modulus of elasticity, and a reduction in surface hardness are some of the consequences of increased temperatures on the properties of these types of material [1–۸]. Few attempts have been made to study the effect of temperature distribution on reinforced soil structures (due to ambient temperature variations). Segrestin and Jailloux [9] investigated the effect of temperature variation on the geosynthetic aging and discovered that in a reinforced soil structure, the temperature within the backfill varies to a depth of 10 m. A seven-year observation of a reinforced earth structure on the M25 motorway at Waltham Cross, UK, carried out by Murray and Farrar [10]. Their observation showed that 0.3 m behind the facing, soil temperature was relatively close to ambient temperature and after a distance of almost 4 m from the nearest external boundary, the soil temperature was constant. Kasozi et al. [8] studied numerically the temperature distribution in a mechanically stabilized earth wall structure in Las Vegas, NV using field data from the Tanque-Verde MSE wall in Tucson, AZ. Based on their study, the overall average temperature within the backfill was much higher than the highlighted test in ASTM D6637 [11].