SIMPLE ESTIMATION METHOD FOR SURFACE SETTLEMENT ACCORDING TO EXCAVATION OF VINOCULAR TUNNELS

Abstract

Many binocular tunnels have been constructed under the difficult surface conditions such buildings or lifelines. While excavating a binocular tunnel, more than three cutting faces pass through an identical section and the settlement of ground surface increases in every heading. Therefore it is very important to estimate and forecast the final surface settlement by using field measurement. In this research, the authors paid attention to the ratio of surface settlement occurs in every excavation stage (primary and secondary tunnel) of binocular tunnels, and we analyzed the ratio of the surface settlement of primary side to secondary side by using the measurement result of past cases. From this analysis, we propose a simple forecast method, which estimates the final settelement from the early settlement occurs in primary excavation side.