The Principle of Invariant Stress of the Surrounding Rock of the Hole under the Condition of Equal Pressure in the Deep Rock Mass

Table 1

Rock mechanics parameters and model stress conditions of three forms.

Lithology	Compressive strength (MPa)	Tensile strength (MPa)	Elastic modulus (GPa)	Poisson ratio	Cohesion (MPa)	The angle of internal friction (°)
Coal	9.42	0.35	22.96	0.23	3	25
Mudstone	20.78	1.91	10.35	0.24	6	30
Sandy mudstone	34.57	4.39	2.69	0.22	9	35