how do stress forces affect rock?

Answer 1

A variety of conditions could happen, depending on the stress and duration;

1. Cracks
2. Breaks
3. Shrinks - due to creep
4 Changes composition

Answer 2

same way they effect any matter. The stresses create strain, elastic strain and, if the yield stress is exceeded, plastic strain. Elastic is like a rubber band, plastic is like silly putty. If the material has very little ductility, the strain can create fracture. One of the most dangerous things in a hard rock mine (deep underground) is the "rock bursts" where the rock pillars that are left in place to support the roof suffer sudden fracture, releasing strain energy and throwing rocks with very high speed and, possibly allowing the roof to collapse.

There are other effects of stress as well, pressures are high enough that minerals may alter their crystal structure, at high temperatures and pressures, different minerals may crystallize within the rock creating gem stones.

Lot of interesting things happen.

Answer 3

Rock Stress forces, lateral - vertical - horizontal, affect rock slope stress stability. Rock slope stability is determined by fracture zones, number of fractures per foot/yard and angle of instability. By measuring the rock slope dip, diconformity compass direction angle, and frequency of occurance (fractures per ft/yds), the stability of the stress forces on the rock and probability of rock stress failure can be predicted.