International Journal of Rock Mechanics & Mining Sciences 41 (2004) 545

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doi:10.1016/j.ijrm

SINOROCK2004 Paper 3B 24

Analysis of rockbursts that have occurred in a waterwaytunnel in Korea

Seong Min Leea,*, Boo Seong Parkb, Sung Won Leec

aDepartment of Civil Engineering, Youngdong University, 12-1, Sulgye-ri, Youngdong-yup, Youngdong-gun, Chungbuk, South KoreabDepartment of Civil Engineering Technology, Ssangyong Engineering & Construction Co., Ltd., 7-23, Shinchon-dong, Songpa-gu, Seoul, South Korea

cDepartment of Geotechnical Engineering Research, Korea Institute of Construction Technology, 2311, Daehwa-Dong, Ilsan-Gu, Goyang-Si,

Gyeonggi-Do 411-712, South Korea

Abstract

Rockbursts have been a major hazard in deep hard rock mines, but have rarely occurred in tunnels. Due to this reason, the topic

has rarely been studied in Korea. Some cases of rockbursts, however, have been reported during construction of a mountain tunnel

for a waterway, and so this study focuses on analyzing data obtained from the tunnel.

From the analysis of the field data, it was found that rockbursts occurred mainly at the section between the tunnel face and the

TBM operating room, and the rock bursting phenomena lasted up to for 20 days after excavation in certain areas. The data also

show that the bursting spots are located all around the tunnel surface. Fig. 1 shows a typical shape of rockburst occurred at the

crown. The maximum size of bursting spots is usually less than 100 cm. This study also shows the relation among strain energy

density (SED), uniaxial compressive strength (UCS), and brittleness and suggests two new scale systems based on the scale system of

strain energy density. In addition, with these scale systems, it shows that there are potentially higher tendencies for rockbursts in this

specific tunnel.

Moreover this research suggests that the properties of rock and rock mass, rock mass rating (RMR) value, tunneling method,

excavating speed, and depth of tunnel have a strong correlation with rockbursts and that the greatest tendency for rockbursts

(approximately 63%) was in the rock mass with RMR values of 41–60. Approximately 63% of rockbursts occurred within the range

of uniaxial compressive strength of 100–250MPa and approximately 34% of rockbursts occurred at the RQD range of 55–70%. In

future studies, the relation between remnant stress and rockbursts should be analyzed because high remnant stress caused by faults,

dykes and so on is likely to be one of the important factors causing rockbursts.

Keywords: Tunnel; TBM; Rockbursts; RMR; Strain energy density; Brittleness

Fig. 1. A typical shape of rockburst after reinforcement.

ng author. Tel.: 82-43-740-1172; fax: 82-43-740-1179.

sses: sm-lee@youngdong.ac.kr (S.M. Lee), bspark@ssyenc.com (B.S. Park), swlee@kict.re.kr (S.W. Lee).

th paper see CD-ROM attached.

ms.2003.12.135