Collision between 3Dmodels in GroundPlane

Hi

I am using Vuforia Ground Plane in Unity. Using ground plane i was able create different 3D objects(flower vases) on a plane surface. But 3D objects moves through each other even after adding collider and rigid body to them(used box collider for every 3D objects). The 3D objects sometimes flies off when tapped on plane surface(freezed rotation and movement in y direction, so flies off in x-z direction). I tried to reduce the timestep in project settings but ARCamera becomes too slow. I need to prevent 3D objects from moving through each other. Kindly help me.

Regards

Alan