Investigation on Coal Pillar Stability between Different Shapes of Gasifier Cavities under High Temperatures during UCG

Table 1

Mechanical parameters of strata.

Rock	ρ(Kg/m^3)	K(GPa)	G(GPa)	c(MPa)	σt(MPa)	φ(°)
Coal	1421	2.67	1.32	1.20	0.85	20.40
Mudstone	21.47	10.2	5.23	1.30	1.16	23.20
Siltstone	22.05	9.31	5.32	1.60	1.11	38.60
Sandstone	23.11	8.33	5.24	1.50	1.85	36.60
Sandy mudstone	23.16	5.56	2.42	1.40	1.60	28.20

¹ρ: density; K: bulk modulus; G: shear modulus; c: cohesion; σ_t: tensile strength; φ: internal friction angle.