There is a bewilderment about the Roki Tunnel in South Ossetia. People I have conversed with do not understand why the Roki Tunnel was allowed to function and allow the Russian troops inside South Ossetia. It seems like a tactical mistake by the Georgian Army.
But not so. I think leaving the tunnel intact was part of the plan. It actually was a key to the Georgian plan to ethnic cleansing of the Ossetians from South Ossetia.
While the whole world was focused on the Olympics, and Putvedev were on vacation (Putin in Beijing, Medvedev on a cruise on Volga), the Georgians attacked Tskhinvali with Czeck made Grad missiles. Grad is a very inaccurate system and it makes more noise than damage. If you want to scare civilians, you attack them with Grad. The plan was that as the civilians came under an attack at night, they would pack up and leave the next day to North Ossetia through the Roki Tunnel while the Georgian tanks rolled through the city and chased them away. Taking care of the ragtag Ossetian volunteers and the few Russian soldiers would not be a big problem then.
On paper, this plan is brilliant. When taking over a territory you do not want the original civilian population there. Killing them amounts to genocide. It's far easier to get away with ethnic cleansing than genocide, the brilliant minds in Georgia and their Western advisors thought.
Had the Georgians plugged the Roki Tunnel, the civilians would not be able to escape and after taking over South Ossetia, they would have an angry civilian population on their hands. The Russians would not be able to come into South Ossetia but the plan was that by the time the Russians realize what was going on, the civilians would be kicked out and the Georgian troops would be near the tunnel.
Well, it didn't work out that way and they probably regret for not closing the tunnel when the Russians woke up (or, more probably, the Russians knew of these plans through their KGB agents).