Evolution Mechanism and Control of Floor Heave in the Deep Roadway with Retained Bottom Coal

Table 1

Physical and mechanical properties of the surrounding rock.

Stratum lithology	The average thickness (m)	Bulk modulus (GPa)	Shear modulus (GPa)	Tensile strength (MPa)	Cohesion (MPa)	Frictional angle (°)
Compound roof	18.5	13.6	3.7	3.5	12.1	27
Siltstone	3.7	10.3	3.1	3.7	9.2	26
Mudstone	2.3	7.9	2.1	1.1	3.2	23
Siltstone	2.9	16.2	5.3	3.3	7.2	26
Medium sandstone	2.3	13.2	3.7	5.2	13.1	29
No. 2 coal	5.1	3.7	1.3	0.6	2.3	27
Sandy mudstone	5.7	8.8	3.6	2.5	3.2	21
No. 4 coal	0.9	3.7	1.3	0.6	2.3	27
Siltstone	1.9	12.7	3.1	3.2	6.7	26
Fine-grained sandstone	3.3	12.9	2.6	2.1	3.3	23
Compound floor	18.0	9.7	2.6	2.7	3.1	27