evaluation of engineering geological properties of chapar-abad alluvial dam foundation: revisiting sealing problems

considering the seepage and choosing an efficient sealing method is very important in dam projects. this issue has a close relationship with engineering geological properties of the dam site. chapar-abad dam is an inhomogeneous earth-fill dam of 44.5 meters height, crest length about 427 meters and a reservoir capacity of 127 million cubic meters. the dam project is under construction and is located about 75 km southeast of uromieh city, in west azerbaijan province. the foundation materials include 60 meters of alluvium deposits overburden bedrock layers of carbonate units. the abutments consist of carbonate and schistose layers of precambrian age. in order to control the seepage through the alluvial foundation, several sealing methods were considered. the methods include grout curtain, cutoff-wall, impervious blanket, open compacted trenches, and the use of geosynthetics are evaluated. in this research using a finite element package named plaxis was utilized. the results indicate that although the cutoff-wall is usually considered as the best method for this type of geological condition, but due to the instability of granular soils and the possibility of liquefaction capability, the grout curtain is proposed as to be an efficient method.