Deal damage to the arcane locked item until it's destroyed
The 2nd-level Sor/Wiz spell arcane lock [abjur] (Player's Handbook 200-1) is cast on a "door, chest, or portal" and "magically locks it." Despite the name, the spell doesn't create a magical lock that itself can be opened or broken—the spell's effect merely secures the item against opening or breaking. However, that doesn't make an item warded by an arcane lock spell impassable or unable to be opened.
Absent access to the 2nd-level Sor/Wiz spell knock [trans] (PH 246) and the 3rd-level Sor/Wiz spell dispel magic [abjur] (PH 223) et al., or perhaps a chime of opening (Dungeon Master's Guide 252) (3,000 gp; 1 lbs.) or other spells and magic items that can bypass an arcane lock effect, the typical way to bypass the effect is not to try to exceed the item's break DC—that's challenging enough without the arcane lock spell adding +10 to the item's break DC—, but, instead, to deal enough damage to destroy the warded item. Breaking and Entering covers both break DCs and hardness and hp for common items. (The DM makes up stats for uncommon items, but many published adventures include the break DC and hardness and hp for their environmental features.)
This makes the spell arcane lock best used in areas that are already guarded, where nearby patrols can hear folks that are pounding with their heavy maces and great axes against doors that they can't get through because of an arcane lock effect. It also make the spell arcane lock good for a low-level fleeing wizard—it usually takes a few rounds for even tough low-level foes to destroy outright a solid door, and that's often enough time for the wizard to escape her foes' clutches.