LONG-TERM CHARACTERISTICS OF SHOTCRETE LINING IN TEST TUNNEL

摘要

This study is to evaluate long-term characteristics of shotcrete lining in test tunnel built in 1996 in Korea, Visual examination, carbonation depth, water analysis, compressive strength, X-ray diffraction (XRD) analysis, and Scanning Election Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analyses were performed to evaluate the properties of shotcrete on long term. 6 shotcrete specimens were cored in the test tunnel, and ground water were collected at 2 positions in tunnel. From the visual examination, crack and efflorescence were widely existed on shotcrete surface. From the test results, pH values of gioundwater and carbonation depth of shotciete specimens were 7.42-7.50 and 3.1-22.8mm, respectively. The compressive strengths of shotcrete specimens by Schmidt hammer and uniaxial were 12.98-24.52MPa and 8.0-19,OMPa. The formation of gypsum and ettringite, which decrease the durability of shotcrete, was detected in the shotcrete specimens from the XRD, SEM, and EDS analyses. It is showed that the shotciete have been deteriorated by chemical components in the groundwater.