Yeah I followed a link from an Australian news website to here. Well done folks.
Hmmm I found this post really interesting simply because I am a Chinese. So I started doing some research in Chinese. From what I have found in Chinese official reports and posts in various forums, I can definately tell that this place is a military drilling area. Appreantly it was built long time back and has been one of the training base for Beijing Military Division since. It appears every summer a large number of soliders, tanks, artilery and armed vehicles gather in the base for all kinds of drilling activities. It is a multi-functional coordinated training camp.