Those smiley face launch pads are much more interesting than the plain circular ones.  I have not zoomed out from any of them to test this out, so maybe I'm all wet, but....  I don't know exactly how it works, and I'm not familiar with the details of the guidance systems on these Chinese missiles, but I am pretty sure those arcs reveal some information about the intended firing arcs of the missiles.  Older missile systems often have a facing.  Something to do with the guidance and control system design requires some missile designs to be turned to "face" in the direction of its target; or "aimed" at the target, if you will.  Part of that process requires a contraption of some sort (the word "theodolite" comes to mind, but I'm not sure that's it) to be very accurately placed in a specific relationship to the missile, but I don't know any further details except that I'm pretty sure it would be placed somewhere on that arc.  However I'm not sure whether it would be placed either in line between the missile and the target or at some angle to the line from the missile to the target, so I'm not sure if we can really tell what target areas the Chinese have in mind until that's resolved (assuming I'm even right to begin with).

 

The large circular pads are set up for the older liquid fuel missiles.  The missiles required a number of support vehicles near the pad prior to a launch.

 

The semi-circle pads are most likely similar in function.

It would appear the semi-circles are in this pattern because of the physical location of the site - not for some pre-positioning for launch.  In other words, they built the ramps based on the local terrain and the position of the road in order to facilitate cost and maneuver the long TEL vehicles onto the launch area - not to point the missiles at anything in particular.

 

The DF-21 is a solid fueld missile fired by a cold tube launch system (gas ejection) directly from the TEL.  The electronic guidance is done right from the launch and support vehicles.  All the PLA 2nd troops have to do is park, point the bugger skyward, plug in the target co-ordinates and light the fuse.

 

The older DF-4 (phased out) was a liquid fueled beast which required a launch pad to be dropped and the missile erected/fueled in the upright position prior to launch.  This required the various support vehicles to be positioned around the missile prior to launch - some of them very heavy - loaded with nasty fuel and oxidizers.  You kinda need a large hard concrete surface to work off or else - ka blam!

 

I will get a few of the DF-21 pads posted shortly.  They are much smaller and harder to spot.

Would the half smiley face have something that works with the PLA's GPS system?  Do these smiles face India or the arc of the orbits of the guidance satellites?

After a bit of further research - you are right.  The older versions of the DF-4 had a clock work (mechanical) guidance system that required a pre-positioned launch.  The angles of the launch sites indicate either Russian missile fields or India were the main targets. 

 

While they have no such use today - with the advanced electronic guidance systems on the DF-21 - they did serve this purpose up until the DF-4 was phased out.

Hey!  Don't quote Nanhe when I'm the one that was right.  People might get the wrong impression and fail to properly perceive my brilliance!  ;-)