Table 1: Inflows greater than 20l/sec in the west side of access tunnel b

Note: 1) Water inflow of 200l/sec from a probe hole at BK1+130 burst into the tunnel 35m away. Within the 30m long tunnel, water came from everywhere and there were more than 10 holes with inflows. The maximum inflow at Sta. BK1+137 on 23 September 2004 (Figure 6), reduced to 1000l/sec after 30minutes, 260l/sec after 24 hours, and vanished after the Tunnel A at AK1+270 was excavated. Inflows are related to N55W/70NE fault f1 and the fractured zone that consists of karst denudation, dissolution small cavities connected in a fissure in marble of T2z group.
2) At Sta. BK2+637, inflow started on 20 April 2005. Maximum inflow of about 15.6m3/sec reduced to 240l/sec after 19 days, and vanished after two months. The flow has a large amount of sediment and stopped work for a week. Located in Class I structure surface, Fault f6 influenced the fractured zone that consists of karst denudation, dissolution small cavities connected in a fissure, and a karst cavern of 15m high, 5m wide found in marble of T2z group.
3) Related to fault f9 and its influence zone consisting of six fractured zones of NE orientation. Water burst into the tunnel 45m away, at a pressure of 4MPa, dropping water all along the section with inflows on the south side wall. The fractured zone consists of well developed fissures, karst denudation fissures, openings and karst cavities in marble of T2b group.
4) Water bearing structures influence the zone in the hanging wall of fault f11, consisting of tensile fissures and karst cavities in marble rock of T2b group. The fractured zone is connected with the water bearing zone in section AK5+150~+240 in Tunnel A.

Section length Initial/Max inflow Inflow after post grouting Description of the inflow and hydrogeological conditions
Date Station
No. From To From To m l/sec l/sec
1 2004.09.02 BK1+078 ~+164 86 7000 0 (See note 1)
2 2004.11.25 0 BK1+780 ~+790 10 25 Fault f2 and its affected zone.
3 2004.12.25 0 BK1+886 ~+893 7 30 Fault f3 affected zone.
4 2005.04.20~ 5.9 BK2+637 ~+690 55 15600 (See note 2)
5 2005.06.17~ 19 BK2+930 ~+940 10 30
6 2006.02.13 BK4+510 ~+520 10 25
7 2006.02.27~ 3.08 BK4+610 ~+690 80 30 fissure zone width about 2m.
8 2006.03.10 0 BK4+742 ~+760 18 30 30
9 2006.03.15~ 3.18 BK4+742 ~+760 18 300 Fault f7 and its affected zone. In-burst water to tunnel 10m away.
10 2006.04.07~ 4.1 BK4+905 ~+927 22 150 45 May related to Fault f5. Three blasting holes inflow to 20m away.
11 2006.05.02~ 5.09 BK5+071 ~+098 27 400 130 (See note 3)
12 2006.05.11~ 5.23 BK5+100 ~+216 116 200 Fracture zones
13 2006.05.28~ 6.06 BK5+223 ~+290 67 300 165 Fault f10 and f11 and affected zones.
14 2006.06.08~ 6.12 BK5+307 ~+346 39 300 115 (See note 4)
15 2006.07.01 0 BK5+431 ~+439 8 20 5 Fault f11 affected zone.
16 2006.08.17~ 8.22 BK5+768 ~+830 62 20 15 Fault f12 and its affected zone.
17 2006.09.16~ 9.27 BK5+980~ BK6+090 110 120 30 Fault f12 and its affected zone.
18 2006.10.12 ~10.19 BK6+150 ~+220 70 40 50
19 2006.10.24~ 11.05 BK6+250 ~+340 90 280 35 Fault f15 and its affected zone
20 2006.11.05~ 11.17 BK6+340 ~+400 60 65 Fault f15 and its affected zone
21 2006.11.17~ 12.12 BK6+400 ~+510 110 450 20 Two faults of NE and one NNW.
Total (steady inflow) 1057 2815 682