Dear reader here we will discuss about eruption of seepage with seepage materials under foundation of dam towards downstream and this phenomenon is expressed as springs in downstream portion of dam.
We are providing embankment materials, considering various factors of failure and designed compaction parameter to have desired uniformity. Thus embankment materials are more or less uniform for a well compacted dam construction.
In contrast to embankment material, foundation often consists of less dense and erratic materials. Though extensive geologic and geotechnical surveys are conducted in this regard, but inhomogeneity is very common, even in very carefully selected dam site.
This inhomogeneity in foundation material, as discussed in previous posts, resulted seepage concentration which ultimately make its way to downstream and in this case they erupted in downstream portion of dam traveling through foundation soils.
This eruption is called springs and is considered potential dangerous in downstream natural ground. A careful observation is required to identify springs. Otherwise complete failure through piping in inevitable.
We have already known that piping failure is catastrophic failure of dam and its foundation. The extremity of springs is reached in the form of sand boiling.
We will learn about sand boiling in our next post and necessary measures to treat such failure.