Comprehensive Analysis of Stability of Coal Seam Composite Roof Based on Analytic Hierarchy Process

Table 1

Physical and mechanical parameters of sandstone.

Kinds of strata	Dry density γ (kN/m^3)	Natural water absorption	Softening coefficient	Compressive strength σ (MPa)	Tensile strength σt (MPa)	Elasticity moduli E (10^4 MPa)	Poisson ratio µ	Internal friction angle (°)	Cohesion C (MPa)
Yellow sandstone	21.551	5.140	0.588	36.669	1.360	2.810	0.086	36.760	7.054
Black sandstone	25.224	1.910	0.812	64.171	2.390	2.020	0.070	37.344	9.891