## 1 Introduction  
The concept of reinforced soil is not new and is believed to have already existed since the 5 th and 4 th millennium BC. Primeval people used reeds, straw, branches, or sticks as reinforcements [1, 2, 3]. Around the early 1970s, geosetvities were used as reinforcements. One of the first geosetville-reinforced walls in the United States was built in Siskiyou National Forest, Oregon. In 1971, the first geosettile-reinforced soil was constructed in France for improving embankment stability. A similar structure was first constructed in the United States in 1974. Around the early 1980s, geogrids were developed and used as soil reinforcements. In 1981, the first geogrid-reinforced earth was used. The extensive use in the United States began in about 1983 [1, 2, 4, 5, 6, 7]. The technology has been widely used as temporary support on permanent roadway embankments. Since then, there has been a significant increase on the application of geosynthetic-reinforced soil. In the United States, the application of geosynthetic-reinforced soil (GRS), a retaining wall (RW) as a bridge abutment was initially developed by the Federal Highway Administration (FHWA), called the GRS--integrated bridge system (GRS-IRS). There are several variations of this technology. Typically, the GRS-IRS includes a GRS abutment, reinforced soil foundation (RSF), bearing bed reinforcement, bridge seat, and an integrated approach (see Figure 1). The RSF is composed of granular fill material that is compacted and encapsulated with a geotextile. It increases the bearing capacity and width of the GRS abutment. The GRS abutment uses alternating backfill layers that are well-compacted and short-spaced geosynthetic reinforcement to provide support for the bridge. The bridge is placed directly on the bridge seat of the GRS abutment without joints or the use of bearing. Under the bridge seat is the bearing bed reinforcement zone, which provides support for the bridge loads. This technology also has an integrated approach that provides a smooth transition without joints between the superstructure and alleviates the problem on the differential settlement between bridge abutments and approach roadways [1,8]. In Japan, a GRS RW with staged-construction FHR facing was developed in the mid-1980s. Since 1987, a large number of permanent GRS retaining walls (RWs) with FHR facings have been built supporting railways, including the high-speed train lines in Japan. An extension of this technology was then developed in the 2000s as a bridge abutment. There are a couple of new bridge systems that have been replacing the conventional-type bridges which use the GRS technology developed. One example concerns the GRS integral bridge (GRS-IB) technology, which includes a continuous girder wherein both ends are structurally connected without using bearings to the top of the FHR facing of a pair of GRS RWs. The GRS-IB technology alleviates the technical problems of conventional bridges, solving the problems of RC structures by eliminating the bearings and joints, and has solved several problems related to the backfill through the use of geosynthetic reinforcement. The GRS-IB composed of a GRS RW as a bridge abutment with a staged-construction full height rigid (FHR) facing and integrated with the continuous reinforced concrete (RC) girder on top of the FHR facing without bearings and joint is depicted in Figure 2[9, 10, 11, 12, 13, 14]. Figure 1: Typical GRS—integrated bridge system [8]. The GRS-IBS and GRS with FHR have been adopted by advanced countries in Asia as well as in Europe, overthrowing the conventional bridges because of its economical, construction, and structural advantages [9; 10; 11; 12; 15; 16]. In the Philippines, no literature has shown that this technology has been used to date. Thus, the authors envisioned the use an integral bridge (IB) using geosynthetic-reinforced soil (GRS) with full height rigid (FHR) facing bridge abutment in the Philippines, which is prone to severe earthquakes.