Assessment of Fractures in Excavation Damaged Zone around Roadways of an Iron Mine Using Optical Televiewer Detecting Method

Table 3

The percentage of effective length of each partition and its percentage in the effective length of corresponding hole.

Hole number	Total length/m	Effective length/m	Intact rock mass/effective length (%)	Joint zone/effective length (%)	Fracture zone/effective length (%)	Broken zone/effective length (%)
1	31.73	12.85	18.0	31.0	32.8	18.2
2	14.67	14.45	0.0	25.3	43.0	31.7
3	14.74	14.74	29.9	41.4	26.3	2.4
4	13.25	13.12	23.8	15.5	37.7	23.0
5	13.57	13.57	28.6	54.9	15.3	1.2
6	14.04	7.6	0.0	90.0	10.0	0.0
7	13.67	13.67	0.0	57.4	36.6	6.0
8	13.29	12.9	4.7	39.8	55.5	0.0
9	13.86	13.78	36.1	21.5	32.6	9.9
10	13.56	13.3	40.7	41.1	15.9	2.3
11	13.73	13.6	18.5	15.3	41.9	24.3
12	13.61	13.53	11.2	20.8	35.2	32.9
13	13.48	13.4	0.0	35.5	51.3	13.1
14	12.05	6.76	0.0	37.3	0.0	62.7
15	12.75	12.67	0.0	44.8	43.6	11.6
16	11.73	10.34	0.0	63.2	27.9	9.0
17	12.35	12.03	0.0	22.7	63.3	14.0
19	12.56	11.92	7.8	45.7	33.9	12.6
20	12.55	3.62	0.0	29.8	55.8	14.4
21	13.84	13.84	0.0	41.7	46.2	12.1
22	12.41	12.14	0.0	32.0	35.9	32.0
23	12.4	12.4	0.0	47.7	41.9	10.5
Total of IV grade surrounding rock	138.36	116.87	15.7	29.3	38.5	16.5
Total of II and III grade surrounding rock	107.72	95.44	10.9	46.5	30.6	12.0
Total of horizontal hole	63.76	53.92	1.7	41.0	40.8	16.5