To conduct the holding action of a subbase course, etc., and percussion and impulse action by pivoting a ripper main body curved in an inverted semicircular shape to a support member, to which a crushing arm is connected continuously, by a pivotal shaft section at the front end of a whirling arm for a civil engineering machine.

The substrate 1b of a rippe main body 1, which is formed in an inverted semicircular shape and to which a sharp edge 2 is formed, is pivoted to a support member 4 mounted at the front end of a whirling arm 6 by a pivotal shaft 3. Not only a pointed shape but also a spatula-like shape that a subbase course X is easy to be peeled may also be used as the sharp edge 2. An arbitrary curved shape such as a U shape, a chevron shape, etc., is selected as the main body 1. A crushing arm 7, which is faced oppositely to the curved section of the main body 1 and in which an impulse horn 8 is formed in the front and striking edges 9, 10 in the downward direction, is integrally connected continuously to the support member 4. The subbase course X, etc., are peeled by the sharp edge 2, and the subbase course X, etc., are percussed and broken by the striking edges 9, 10 worked while using the pivotal shaft 3 as a support, and struck against a bedrock, etc., and destroyed by the impulse horn 8. Accordingly, the sawing and dropping works of fragmented stones and column jointing rocks of the subbase course, etc., can be conducted.