Yes Pokémon with the Sheer Force Ability do not lose any HP from a Life Orb when using a move that has an additional effect.
From Bulbapedia: "If an item has two effects, only the effect(s) that activate after attacking will be negated. Therefore, if a Pokémon holds a Life Orb, it will gain the passive damage boost (because it is not activated after the attack) but the recoil effect afterward will be ignored."
Source: Experience and Bulbapedia
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