-The hydraulic fracturing tests were conducted to determine the in-situ state of stress to design the underground powerhouse in the present investigation.

• Hydraulic fracturing involves applying hydraulic pressure to a drill hole to determine the fracture pressure and hence the stress.

The vertical stress was calculated based on the height of the overburden at that location. A length of borehole is chosen for the stress measurements and an interval, typically 1 m long, is located for the test and isolated using a straddle packer system.

It is often a completely unjustified assumption that the borehole is indeed parallel to a principal stress. The hydraulic fracturing method is the only direct method available for stress measurement at any significant distance from the observer

Simple calculation to determine vertical stress

The sum of all the pressures applied by all of the different rock layers

Every formation contains fluid and rock and each one must be encounted for separately

Porosity correlation can be simply used to define the amount of space that is occupied by fluid versus the amount of space that is occupied by rock