Seems like there are lots of people having the same issue right now! For example, check my thread "Stuck fermentation with a belgian strong". I've seen a few other threads regarding stuck fermentation. I realized that I overlooked a couple of things. For one, my pitch rate was too low. Here is the text from Wyeast's technical information page on "High Gravity Brewing":
"Pitch Rates
Increased wort gravity causes increased stress on yeast due to increased osmotic pressure and increased alcohol levels. It is necessary to increase your pitch rates when increasing the wort gravity. A general rule of thumb is to pitch one million cells per milliliter per degree plato. So a 20 degree plato (1.080 s.g.) wort would require 20 million cells per milliliter per degree plato.
Home brewers will either need to pitch more packages of yeast or make a starter. When using an Activator 125ml package, 1 package to 5 gallons will give around 6 million cells per milliter. This is clearly too low for high gravity brewing and will cause inconsistent results and usually high terminal gravities."
My initial gravity was 1.088 and I only pitched one pack of Wyeast, so I should have increased that. The temps in my basement also got too low after the first few days of vigorous fermentation - they were at ~68 or so, way too low for a big belgian. My gravity was stuck at ~1.046 after 2 weeks. So I pitched a pack of Red Star champagne yeast (by my LHBS recommendation, others on here said they would have held off on that), and then stepped the temperature up to 72 - 80, and after a day of increased activity in the airlock, I've been agitating the beer every day to re-suspend the flocculated yeast.
The activity has been decent for the past week, but I haven't re-checked the gravity yet. I'm hoping I get down in the 1.02's at least before I rack to the secondary.
So anyway, maybe you could check your temperatures and make sure they're near the upper range of the WLP051 recommended temperature range. And after you know you have a relatively oxygen free headspace, (i.e. I don't know how long its been since you opened it up to check your gravity) start shaking up your carboy on a daily basis to wake up the yeast a bit.
There are probably several suggestions from others that will help you out too, this is also my first time encountering the problem so I'm still learning how to deal with it.
