CASE STUDY OF A REINFORCED SOIL SLOPE WITH MARGINAL BACKFILL AS A DETENTION POND IN FLOOD CONTROL

Nelson N.S. Chou ； Kuo-Hsin Yang ； Hsin-Ming Wu ； Jia-Jing Lin ； Shiau Jing Ho ； Cheng-Nan Liu

《Journal of GeoEngineering》 18卷1期 (2023/03) Pp. 33-47

https://doi.org/10.6310/jog.202303_18(1).4

摘要

This paper presents a unique case of a detention pond within a freeway interchange ramp. A wrap-around geosynthetic-reinforced soil slope (RSS) backfilled with marginal soil was used as the waterfront retaining structure of the detention pond. In general, RSS with marginal backfill is considered unsuitable for waterfront structures because the infiltration or saturation may adversely affect the performance and stability of the slope. However, for this project, the short flooding duration and low permeability of the clayey backfill limited the saturated zone to the front face of the slope. Because the RSS is an internally stable structure, saturation of the front face does not affect the overall system stability. Details of the design and construction of the RSS are first discussed. A series of transient seepage and slope stability analyses were then performed to evaluate the effect of porewater pressure caused by flooding on the global stability of the RSS. Moreover, a hypothetical case involving critical conditions-a high phreatic surface in the reinforced zones and no external water in the detention pond (i.e., drawdown conditions)-was analyzed. The project was completed in November 2015, and since then, the RSS in the detention pond has encountered more than 15 complete flooding and discharge cycles without any damage or observable deformation. This study demonstrated that RSS is a sustainable solution for infrastructure development that effectively balances safety, costs, ecological concerns and reduces waste, pollution, and CO_2 emissions.

關鍵字

Geosynthetic-reinforced soil slope ； waterfront retaining system ； flood detention pond ； marginal backfill ； sustainability