Yes, there are. The example-networks folder on your ASCE installation contains a few examples (based on real safety cases).
Also, the Adelard Safety Case Development Manual, which includes an example of a safety case, is installed with ASCE or can be
downloaded from the ASCAD page.
If you require additional examples, please contact Adelard directly on +44 (0) 20 7490 9450 to discuss your needs.