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

Note: 1) Tunnel A at Sta. AK1+117 encountered a large water inflow of about 150l/sec and pressure 1.2MPa, jetting 16m out from the wall on 25 July 2004. More than 20 locations experienced various inflows and dropping water – these inflows varied from 20 to 150l/sec. Inflow vanished after about 40 days. Seal work took two months. Inflows are from N55W/70NE fault f1 influenced fracture zones that consist of karst denudation fissures, dissolution small cavities connected by fissures. Water related to a small fault has a width of 0.2-0.5m and an influenced zone of 1-2m. The gushing water came from a 1-2cm wide opening. The rock is marble in T2z group.
2) Inflow from blasting or rockbolt holes ranged from 50~100l/sec, pressure 1~2MPa. Water jetted a maximum distance of 45m to the tunnel. Up to 7 October 2006, there was still about 1050l/sec inflow in total, with dropping water all along the section with more than 30 inflows. There are faults f10 and f11 crushed zones oriented NEE and SEE, along which exist well developed karst denudation fissures, channels and cavities, and some karst caverns in sizes of 0.5m x 0.5m, 0.8m x 1.2m, 1.2m x 1.4m in the hanging wall of Fault f11, in marble of T2b group. Figure 9 shows the water bearing structures in a typical section in the west side tunnels in T2b rock group.

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 2004.07.24 9.3 Ak1+088 ~+117 29 300 (See note 1)
2 2004.10.20~ 11.12 AK1+246 ~+310 64 200 fissures along a fault of NW-SE
3 2005.05.20~ 5.23 AK2+630 ~+640 10 25 Fault f6 affected zone
4 2006.03.25 AK4+695 ~+707 12 100 50 Fault f5
5 2006.03.27~ 4.02 AK4+720 ~+758 38 30 Fault f5 affected zone
6 2006.05.03 AK5+009 ~+013 4 80 0
7 2006.05.06 AK5+038 ~+061 23 150 0 Fault f9
8 2006.05.13~ 5.17 AK5+098 ~+113 15 50 fissures zone
9 2006.05.19 AK5+139 ~+143 4 150 A fault
10 2006.05.23~ 6.11 AK5+150 ~+236 86 1600 500 (See note 2)
11 2006.07.23~ 7.26 AK5+528 ~+551 23 60 0 A fault
12 2006.07.30~ 8.01 AK5+588 ~+602 4 50 0 A fault
13 2006.08.09~ 8.11 AK5+683 ~+699 16 30 0 A fault
14 2006.08.25~ 9.02 AK5+790 ~+850 60 50 40 Fault f12 affected zone
15 2006.09.07 9.09 AK5+880 ~+930 50 40 Fault f12 affected zone
16 2006.09.15 9.21 AK+965~ AK6+010 45 20 A fault
17 2006.10.08 0 AK6+150 ~+210 60 60 fissures zone
18 2006.10.15~ 11.1 AK6+210 ~+408 198 200 20 Fault f15 affected zone
19 2006.11.10~ 11.18 AK6+408 ~+446 38 120 20 fissures zone
20 2006.11.26 0 AK6+446 ~+490 44 80 5 A fault
21 2007.02.08 AK6+995 2 400 190 Karst cavern
Total (steady inflow) 825 2765 825