PHP is a Turing complete programming language, making it possible to write anything you want that's computationally possible. So yes, you can build AI projects using PHP.
You can refer the following link which has projects based on AI, using PHP:
Here is another project named: Teachers Automatic Time-Table Software Generation System using PHP
Take a look to Program O: http://blog.program-o.com/
Program O is an AIML(stands for Artificial Intelligence Modelling Language. It is an XML based markup language meant to create artificial intelligent applications) engine written in PHP with MySQL. Here you can find support, help, bot add-ons, a brilliant and friendly community and of course the Program O download files.
If you wish to learn Artificial Intelligence visit this Artificial Intelligence Course In Bangalore.
If you are interested in learning AI, I recommend signing up for this Applied AI Course by Intellipaat.