Dynamic Fracture Toughness and Dynamic Tensile Strength of the Rock from Different Depths of Beijing Datai Well

Table 3

Geometry of the standard CCNBD.

Descriptions	Values	Dimensionless expression
Diameter D (mm)	75	—
Thickness B (mm)	30	αB = B/R = 0.8
Initial chevron notched crack length a0 (mm)	9.89	α0 = a0/R = 0.2637
Final chevron notched crack length a1 (mm)	24.37	α1 = a1/R = 0.65
Saw radius Rs (mm)	26	αs = Rs/R = 0.6933
Dimensionless stress intensity factor	0.84	—