A New Width Measurement Method of the Stress Relief Zone on Roadway Surrounding Rocks

Table 1

Strata structure and mechanical parameters of rocks.

No.	Lithology	Depth (m)	Density (kg·m^-3)	Compressive strength (MPa)	Tensile strength (MPa)	Poisson ratio	Elastic modulus (GPa)	Friction angle (°)	Cohesion (MPa)
1	Sandy mudstone	4.2	2300	39	1.12	0.24	10	36	3.4
2	Fine sandstone	19.0	2620	37.9	0.57	0.32	6	40.5	9.2
3	Coal	4.0	1437	8	1.29	0.38	3	30	1.2
4	Mudstone	3.5	2470	25.9	0.90	0.31	13	40	3.5
5	Limestone	6.9	2800	30	0.90	0.23	11	37	2.5
6	Coal	0.7	1437	8	1.29	0.38	3	30	1.2
7	Mudstone	11.7	2470	25.9	0.87	0.31	13	31.1	3.5