It was relatively easy to find a stable, shallow foundation for the north tower.
为北侧塔找到一个稳定、浅的地基相对容易。
英语百科
Shallow foundation
A shallow foundation is a type of foundation which transfers building loads to the earth very near the surface, rather than to a subsurface layer or a range of depths as does a deep foundation. Shallow foundations include spread footing foundations, mat-slab foundations, slab-on-grade foundations, pad foundations, rubble trench foundations and earthbag foundations.