The Settlement Behaviors of Granular Backfill Materials for High Speed Rail Embankment

Taiwan High Speed Rail (THSR) is the most important traffic infrastructure for the next decade in Taiwan. The tracking system is extremely vulnerable to the damage of differential settlement. However, at the transition areas such as bridge approach, differential settlement will likely occur due to different material stiffness. Use of cement-treated technical backfill instead of conventional granular backfill has shown promising hydrocollapse reduction and strength increase. However, the improvement will be limited due to the limited moisture within the material for cement hydration. Based on the research, technical backfill treated with 3.2 to 7.5% cement can minimize the hydrocollapse. For best service results, technical backfill still requires to be compacted to 95 % of the modified Proctor density with moisture content preferably of about OMC+2 %. The results of the study provide helpful suggestions to control the settlement potential for the THSR embankment.