Measured Settlement of Highways Improved by Lightweight Backfilling Without Road Closure

Excessive post-construction settlement is often found for highways built on soft soil, slowing driving speed and increasing the risk of traffic accidents. Increasing attention has been paid to lightweight backfill to reduce ground settlement because of its light density, reasonable cost, and ease of construction. However, the existing technology for lightweight backfilling requires road closure, resulting in serious traffic jams and considerable economic losses. In this paper, a new technology is proposed for lightweight backfilling without road closure. A field trial was conducted to verify the practicality of the newly proposed technology. Ground settlements during and after construction were measured in the field trial with lightweight backfilling and in the adjacent zone without lightweight backfilling. The measured results were compared, discussed, and explained. It was found that the ground settlement was significantly mitigated by lightweight backfilling. The total settlement of ground surface was reduced by 36 %, and the average settlement rate was reduced by 40 % with a decreasing trend. It is suggested that the proposed technology with lightweight backfilling could solve the post-construction settlement problem well without road closure in busy highway.