How can thrust blocks resist unbalanced force in horizontal bends in watermain?

Thrust block resists the unbalanced force in two common approaches. In the first approach, thrust block serves as gravity block which makes use of its own dead weight to resist the thrust forces. An example of this application is vertical down bends.’

The second approach of thrust block to resist unbalanced forces in watermain involves providing a larger bearing area so that the resulting pressure against the soils does not exceed the bearing capacity of soils. Therefore, the function of thrust block in this case is to make use of stiffness of concrete to spread the thrust force into larger area. An example of this application is horizontal bends in watermain.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.