Alteration in Material Properties of an Intact Rock due to Drilling and Bolting Operations

Table 2

(a) Uniaxial compressive strength of virgin and bolted specimens and percent reduction in strength. (b) Tangent modulus of virgin and bolted specimens and percent reduction in modulus.

(a)

Serial number	𝜎𝑐, MPa	𝜎𝑐𝑟, MPa	% reduction in strength
1	23.58	22.18	5.94
2	26.75	19.75	26.17
3	33.79	33.53	0.77
4	19.31	17.76	8.03
5	108.08	38.44	64.43
6	101.18	87.8	13.22
7	122.85	37.83	69.21
8	79.56	58.76	26.14

(b)

Serial number	𝐸𝑐, MPa	𝐸𝑐𝑟, MPa	% reduction in modulus
1	13000	5000	61.54
2	6500	5000	23.08
3	5330	5200	2.44
4	5660	2600	54.06
5	18600	6130	67.04
6	15830	12500	21.04
7	16740	6300	62.37
8	12800	7000	45.31