The OP is looking to use "jail"-like technologies for virtualization.
I have used chroot for virtualization on OpenBSD. For some purposes, it works well, but there are some caveats for using it this way, requireing careful planning:
- The use of chroot only virtualizes file systems. Processes, network stack, and kernel remain unvirtualized.
- Superuser functionality in a chrooted environment is not equivalent to running as the superuser in normal operation. Some functionality is intentionally eliminated.
Apache itself can provide virtual hosting, and that is probably the easiest way to accomplish the appearance of multiple webservers within a single OS.