I am far from an expert on particles considering it is an area of Blender I've only just begun playing with in the last couple weeks but if you are just trying to keep particles from going through something, then under physics you can just set that object to be a collision object. Here's a screenshot where I have two planes in the scene, one is emitting particles (just using some basic UV spheres I have on another layer as the particles so that it is easier to see) and the other is set as a collision object. See how the particles are not passing through the bottom plane? Is that the effect you are going for?