Piping Failure Remediation of Barrage Structure: from Analysis to Construction

Piping is the internal erosion under a dam/barrage structure because of seepage flow through the deposit of a granular soil layer. This phenomenon can cause a cavity under the barrage structure and trigger a collapse. Many water structures in Indonesia are made with simple structures so people can build them independently without heavy equipment; for example, the boulder barrage in Tinggar Buntut, Mojokerto. This barrage faced quite large piping. This study will present a detailed analysis and construction method for piping repair. Piping failure remediation of a barrage or other water structure required comprehensive approach including site observation, interview to the people in the nearest society, collect as built and historical data of the structure, conduct a good quality of soil investigation both in-situ and laboratory test, perform desk study and technical analysis, and good construction process and procedure. The piping analysis check can be done by using conventional methods like Lane’s creep theory and numerical modelling like finite element by Plaxis software. Both methods give a good understanding regarding the piping mechanism and how to counter the potential piping failure. The best solution to increase factors of safety against piping is to add vertical wall. The construction method that can be utilized including strengthening the existing structure with concrete overlay and conduct grouting to the existence of crack or hole in the structure or surrounding supporting structure.