Analysis of the Causes of Contractor's Claims in the DB Contracts of Underground Project in Iran

There are some possibility of claims` occurrence by both contract’s sides especially contractors in most of project that this claims negatively affect project implementation and can be prevented by cognition of main Causes of claims` occurrence. In this regard authors gather 250 reasons related to claim in underground design-Build projects. After the analyzing of these reasons closed questionaries'' include of frequency and intensity of impact in three level (first level consist of 5 group، second level consist of 16 group and third one 43 group) were produced and distributed through its perpetrators، include of The employer and contribution to the design and construction who are active in different kinds of underground projects. Then according to the result of this questionaries'' the most important Causes of claims were determined.