The paper studies the mechanics function and break the mechanism of the soft soil foundation,puts forward construction method of the soft soil quality pipe groove dig,key introduces the construction technigue of steel pile shield in deep dig,points out finally that the engineering deal of open dig the groove is big specific weight in the piping under construction,should cause to value.

Analysis is made of the source of thermal powdered slag and its engineering properties, with several trial road sections in some practical projects, where this kind of slag is used for the trench backfill.

Introduced here is the engineering application of the heat-stewed steel slag to replace sand for trench backfill, which has greater benefits technical, economic and social, and is worthy of popularization.