Application and Design of Transition Piled Embankment with Surcharged Prefabricated Vertical Drain Intersection over Soft Ground

Abstract

Lately numerous ground treatments are being embraced as the structural approach to regulate the total settlement and differential settlement which is the root of the undulating road problem. A piled embankment is commonly adopted to control the total and differential settlements. While a vertical drain with a surcharge is applied to expedite settlement and transition piles are used to regulate differential settlement, embankment stability is a major drawback for this approach. Therefore, a common industry practice is that both ground treatments are applied to optimize the design and construction. The main concern is the differential settlement at the intersection of these treatments during the post-construction period. A transition piled embankment at the vertical drain with surcharge may resolve this drawback, but long-term settlement must be considered in the design to ensure that the post-ground treatment settlement and differential settlement are kept within the design requirements. This paper proposes the transition piled embankment with a surcharged prefabricated vertical drain. The performance in terms of settlement, cost and time is assessed to establish the effectiveness of the proposed system, which is validated by performing a full-scale field test. By introducing the intersection ground treatment, post-construction settlement and differential settlement are regulated significantly. The cost and time required for the transition piled embankment with surcharged prefabricated vertical drain are also insignificant as compared to conventional ground treatment approaches.