Study on Floor Mechanical Failure Characteristics and Stress Evolution in Double Predriven Recovery Rooms

Table 1

Properties of strata.

Lithology	Thickness (m)	Elastic modulus B(GPa)	Shear modulus S(GPa)	Compressive strength σ (MPa)	Cohesion C(MPa)	Friction angle (°)	Density ρ(Kg/m^3)
Sandy mudstone	4.9	13.0	8.5	9.63	2.51	34.9	2550
Siltstone	4.0	19.0	14.8	27.00	6.01	41.9	2540
Siltstone	5.5	19.0	14.8	27.00	6.01	41.9	2540
Fine sandstone	18.6	18.7	15.2	28.40	6.25	42.5	2550
Sandy mudstone	6.4	13.0	8.5	9.63	2.51	34.9	2550
3–1# coal seam	6.2	11.9	7.1	4.59	1.35	29.2	1400
Mudstone	12.8	12.4	8.1	9.41	2.62	31.7	2550
Siltstone	9.2	19.0	14.8	27.00	6.01	41.9	2540
Sandy mudstone	4.9	13.0	8.5	9.63	2.51	34.9	2550