Study on Reasonable Layout of Upper Protective Layer for Prevention Rock Burst under Coal Seam Group with Close Quarters Conditions

Table 2

A group of optimal parameters of cohesion and internal friction angle.

Strain	0	0.022	0.048	0.062	0.076	0.102	0.135
Cohesion	3.3	3.1	2.9	2.5	2.1	1.7	1.3
Internal friction angle	30	30	28	27	25	23	23