Pour 1 cup of boiling water into a large bowl that will fit all of the pork chops. Make sure the bowl will fit into your refrigerator.
Add the salt and sugar to the water and stir until dissolved.
Add the allspice, fennel seeds, peppercorns, bay leaf, garlic and thyme to the bowl.
Add 7 cups of very cold water to the bowl and stir to combine.
Place the pork chops in the bowl, making sure that they're completely submerged. You can add more water if needed.
Cover the bowl and place it in the refrigerator for at least 6 hours, or up to 24 hours.
Remove the pork chops from the brine and pat dry with paper towels.
Preheat a grill or grill pan to medium high heat.
Place the chops on the grill and cook for 6-8 minutes per side, or until desired level of doneness.
Brush the barbecue sauce all over the pork chops. Cook for 1 minute more on each side.
Remove the pork chops from the grill. Let the chops rest, covered, for 5-10 minutes, then serve.