Abstract: As a key link in the current urban development, the scientific site selecting and planning of a new urban area needs to be based on the clear engineering geological conditions.Taking Tongchuan region as an example,according to the latest geological structure and landform evolution, we determined the types of landform and divided the the sedimentary structures into eolian deposition, fluvial and pluvial deposition, and complex deposition in respect of the Quaternary sediments. According to the results of collapsibility tests, the depth more than 22 m of the loess in the study area is without self-weight collapsibility, and the depth more than 24 m is without collapsibility. Based on the calculation of the collapsibility amount, the study area is graded into non-collapsible areas, level 2, level 3, and level 4 collapsible zone. There are 4 zones (low mountainous, loess platform, loess hilly, andvalley terrace) and 8 sub-zones. On the basis, we summarized the engineering characteristics of each engineering geological area. Of them, the low mountainous areas and loess hilly areas are not suitable for construction; while the level 2 collapsible of high and low loess plateau, part of valley terrace areas after a foundation treatment,and level 3-4 collapse of high and low loess plateaus are suitable for construction. The research results provide some guidance and reference for future urban site selection and project construction planning under similar geological conditions in Loess Plateau.

Key words: Loess Plateau, collapsibility, engineering geological condition, engineering geological division, Tongchuan region