解答:(Ⅰ)证明:连接AC1交A1C于点E,连接DE
因为四边形AA1C1C是矩形,则E为AC1的中点
又D是AB的中点,DE∥BC1,
又DE?面CA1D,BC1?面CA1D,
所以BC1∥面CA1D;
(2)解:AC=BC,D是AB的中点,AB⊥CD,
又AA1⊥面ABC,CD?面ABC,AA1⊥CD,
AA1∩AB=A,CD⊥面AA1B1B,CD?面CA1D,
平面CA1D⊥平面AA1B1B所以CD是三棱锥B1-A1DC的高,
又S△A1B1D=
AB×1 2
=
3
,
3
所以VB1?A1DC=VC?A1B1D=
S△A1B1D×AD=1 3
×1 3
×
3
=1;
3