Rock Load Estimation in Development Galleries and Junctions for Underground Coal Mines: A CMRI-ISM Rock Mass Rating Approach

Table 6

𝑡-test for independent samples (variables treated as independent samples).

S. number	Group 1 versus group 2	Mean group 1	Mean group 2	𝑡-value	df	𝑃; (level of significance)	Remarks
1.	RMR versus calculated rock load; (gallery width 3.6 m)	67.5	21.8	2.0	8	0.05	Number of data are less
2.	RMR versus calculated rock load; (junctions)	67.5	22.6	2.0	8	0.05
3.	RMR versus calculated rock load; (gallery width 4.2 m)	51.0	7.3	7.5	40	0.000000	Number of data are good
4.	RMR versus calculated rock load; (junctions)	51.0	8.1	7.4	40	0.000000
5	RMR versus calculated rock load; (gallery width 4.8 m)	51.3	2.7	15.0	14	0.000000	Number of data are moderate
6	RMR versus calculated rock load; (junctions)	51.3	3.2	14.8	14	0.000000