performance is not always as expected, often due to inability of the impervious layer to accommodate settlements at foundations, settlements due to bad compaction, seismic events, etc.
经常由于防渗层不能适应坝基的沉降、碾压不好造成沉降、地震等等,实施起来并不总是如预期的一样。
this impervious layer or boundary will retard the free diffusion of moisture. this condition is referred to as case hardening.