Mechanical Parameters of Deep-Buried Coal Goaf Rock Mass Based on Optimized GSI Quantitative Analysis

Table 2

Rock mass classification of integrity according to normative standards [16, 17].

Rock mass integrity	Rock mass joint number	Average distance between discontinuities (m)	Rock mass structure
Extremely intact rock	＜3	＞1.0	Intact structure
Relatively intact rock	3–10	1.0–0.4	Blocky structure
Relatively fractured rock	10–20	0.4–0.2	Very blocky-interlocked structure
Fractured rock	20–35	＜0.2	Blocky and disturbed structure
Extremely fractured rock	＞35	—	Disintegrated and laminated structure