The inadequate treatment of raw materials,nonstandard technical operation,abnormal fermentation,and unsound management caursed bitterness,harsh taste,burnt taste and other bad taste in liquor,which would seriously influence liquor quality.

The bad flavor not only affects the sense of mouth, but also depresses the nutritional value of the milk.

Research purposes: The brief introductions are given to the construction technology of tunnel portal in unfavourable geological section and the measures for prevention and treatment of tunnel collapses,and the summary is made for the experience of construction of tunnel portal in unfavourable geological section.