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An important prerequisite for achieving efficient exploitation of coalbed methane wells is through forming map
cracking by hydraulic fracturing. In order to analyze the mechanical mechanism for forming map cracking of the coal bed
with cleats, the mechanical conditions for forming map cracking during hydraulic fracturing process of coal bed was proposed
using extensional faulting in elastic mechanics and the shear damage criterion, and the minimum net pressure calculation
model for forming map cracking was established when the butt cleat and face cleat in coal opened at the same time.
It can be concluded through using the calculation model that the net pressure value that needed for forming map cracking
first decreased and then increased with the increasing of the angle between the face cleat and the direction of horizontal
minimum principal stress. The cleats and fissures developed along the horizontal maximum principal stress were easy to
open and extend under the effect of hydraulic fracturing. The variation of the internal friction coefficient variation of the
face cleat had little effect on the minimum net pressure that was needed for forming map fracturing after the angle between
the direction of face cleat and horizontal minimum principal stress is determined.