Assessment of the Excavation Damaged Zones in the Surrounding Rock of an Underground Powerhouse under High In Situ Stress Using an Acoustic Velocity Detecting Method
Table 1
The results of in situ stress measurements around the Houziyan underground powerhouse.
No.
Points
Location
H-d (m)
V-d (m)
σ1
σ2
σ3
1
σSPD1-1
0 + 253 m in SPD1
253
390
Value (MPa)
21.33
12.06
6.98
α (°)
315.69
147.6
47.32
β (°)
21.53
68.04
4.12
2
σSPD1-2
0 ＋ 400 m in SPD1
400
560
Value (MPa)
29.06
18.44
13.85
α (°)
290.1
15.6
100.3
β (°)
42.5
−4.9
47.1
3
σSPD1-3
0 ＋ 106 m in the lower adit of SPD1
400
570
Value(MPa)
28.07
22.85
16.11
α (°)
305.5
21.2
100.4
β (°)
47.5
−12.8
39.7
4
σSPD1-4
0 ＋ 525 m in SPD1
525
780
Value (MPa)
33.45
22.62
14.12
α (°)
285.3
352.9
73.3
β (°)
54.3
−15.3
31.4
5
σSPD1-5
0 ＋ 236 m in the fourth adit of SPD1
385
576
Value (MPa)
36.43
29.8
22.32
α (°)
319.3
3.3
74.7
β (°)
44.5
−36.2
23.6
6
σSPD9-1
0 ＋ 250 m in SPD9
250
440
Value (MPa)
21.46
17.59
6.2
α (°)
286.2
96.7
11.1
β (°)
47.1
42.5
−4.8
7
σSG-1
0 + 41 m in the 2nd-layer drainage gallery
330
500
Value (MPa)
24.67
11.04
4.83
α (°)
301.3
33.5
123.9
β (°)
67.6
0.9
22.4
8
σSG-2
0 + 90 m in the 2nd-layer drainage gallery
280
480
Value (MPa)
22.67
18.54
9.65
α (°)
288.0
169.4
68.4
β (°)
54.2
19.0
29.0
9
σSG-3
0 + 59 m in the upstream sidewall of No. 2 tailrace tunnel
430
580
Value (MPa)
34.77
19.76
12.26
α (°)
270.0
170.5
62.5
β (°)
34.5
13.5
52.2
Note: H-d is the horizontal depth of the measured point, while V-d is the vertical depth of the measured point. α is the dip direction of the principal stress and β is the dip angle of the principal stress.
