Research on Optimization of Coal Pressure Relief Borehole Parameters under High-Stress Conditions

Table 4

Evaluation of the pressure relief effect of different arrangements of pressure relief boreholes with different diameters.

Evaluation Index

Borehole diameter (mm)

100

120

140

160

180

200

Borehole arrangement

Single row

Three flower

Double row

Single row

Three flower

Double row

Single row

Three flower

Double row

Single row

Three flower

Double row

Single row

Three flower

Double row

Single row

Three flower

Double row

Pressure relief zone thickness

g

p

e

g

p

e

p

g

e

p

g

e

g

p

e

g

p

e

Thickness of stress concentration area

e

g

p

e

g

p

e

g

p

g

e

p

e

g

p

e

g

p

Energy density reduction degree

g

e

p

g

e

p

g

e

p

g

e

p

g

e

p

g

e

p

Stress reduction percentage

g

e

p

e

p

g

p

g

e

e

g

p

e

p

g

e

g

p

Displacement size

p

g

e

p

g

e

p

g

e

p

g

e

p

g

e

p

g

e

Degree of penetration of plastic zone

e

p

g

e

p

g

e

p

g

e

p

g

e

p

g

e

p

g