Steve's 02/25/01 take on concrete fences faring poorly on our constantly shifting Texas soils is on the mark. However, I have built both massive & light retaining walls out of concrete panels set between I-beam mounting posts without any shifting & falling at all, though. What it took was deep boring into the limestone which underlies our highly expansive surface soils rather than the makeshift shallow holes commonly uses to anchor springy, forgiving cyclone fences. The bedding concrete in the boreholes only has to be 3-sack mix or so, but the extent of the boring and the amount of concrete used is considerable. The cost of the I-beams, which have to be waterproofed with epoxy, plus the cost of all that concrete, really adds up, but the result is a tough, good-looking stable wall that retains its shape & appearance indefinitely without soil watering or other maintenance, ever.