A Study on the Lining Stability of Old Tunnel Using Groundwater Flow Modelling and Coupled Stress-Pore Water Pressure Analysis

?????? ???????????? ?????? ???????????? ????????? ?????? ?????? ??????????????? ????????? ???????????? ?????? ?????? ?????? ?????? ????????? ????????? ???????????? ?????? ???????????? ????????? ????????? ??????. ??? ??????????????? ????????? ??? 30????????? ?????? ????????? ????????? ?????? 3??? ????????? ???????????? ????????? ????????? ?????? ???????????? ????????? ?????? ?????? ?????? ?????? ???????????? ??? ????????? ???????????? ????????? ??????????????? ????????? ???????????????. ??????????????? ?????? ????????? ????????? ????????? ?????? ???????????? ???????????? ???????????? ????????? ????????????????????? ???????????? ?????? ???????????? ??????-???????????? ?????? 3?????? ????????????????????? ???????????? ????????? ?????????. ?????? ????????? ?????? ?????? ?????? ???????????? ????????? ????????? ??????????????? ????????? ????????? ???????????? ???????????? ?????? ?????? ??????????????? ????????? ????????? ????????? ??? ????????????, ??? ???????????? ????????? ??????????????? ?????? ????????? ???????????? ?????? ????????? ????????? ?????? ?????? ?????? ??????????????? ????????? ?????? ????????? ??????????????? ???????????? ?????? ???????????? ??????????????? ????????? ??? ??? ?????? ????????? ????????????.The degradation of a tunnel drainage system leads to increases in pore water pressure around the tunnel and the lining stress, which results in affecting the tunnel stability. In the present study of the Namsan 3th tunnel, more than 30 year old tunnel, the effects of the drainage performance reduction due to drain hole clogging on the tunnel lining stability were investigated by examining pore water pressure distribution around the tunnel and the lining stresses through numerical analysis. Groundwater flow modeling on the Mt. Namsan region was done first and 3D seepage and coupled stress-pore water pressure finite element analysis were performed on the tunnel using the results of the groundwater flow modeling. The pore water pressure distribution and the tunnel lining stresses could be predicted using a drain hole outflow data measured in the tunnel site. This analysis method may be used to evaluate the current stability of old tunnels for which in most cases field investigations and related information are not readily available