Estimation of Disturbed Zone Around Rock Masses with Tunnel Excavation Using PS Logging

PS검층에 의한 터널굴착에 따른 주변암반의 이완영역 평가

  • Park, Sam Gyu (Forestry and Forest Products Research Institute, Ministry of Agriculture, Forestry and Fisheries) ;
  • Kim, Hee Joon (Department of Exploration Engineering, Pukyung National University)
  • 박삼규 (일본농림수산성 삼림총합연구소) ;
  • 김희준 (부경대학교 탐사공학과)
  • Received : 1998.05.06
  • Accepted : 1998.11.23
  • Published : 1998.12.31


Excavation of underground openings changes stress distribution around the opening. The survey of this disturbed zone in excavation is very important to design and construct underground facilities, such as tunnel, gas and oil storage, power plant and disposal site of high- and low-level radioactive wastes. This paper presents a zoning of rock masses with tunnel excavation using PS logging. Compressional and shear wave velocities are measured in boreholes drilled in the tunnel wall, which was constructed with blasting and/or machine excavation. The disturbed zone in excavation can be estimated by comparing PS logging data with a tomographic image of compressional wave velocity and compressional and shear wave velocities of core samples. In the side wall of tunnel, the disturbed zone reaches 1.5 m and 1.0 m in thickness for blocks of blasting and machine excavations, respectively. In the roof of tunnel, however, the disturbed zone is 1.0 m and 0.75 m thick for the two blocks. These results show that the width of the disturbed zone is larger in the side wall of tunnel than in the roof, and 1.3 to 1.5 times larger for the blasting excavation than for the machine excavation.