Abstract
It is well known that local earth pressure acts on pre-existing shield tunnel for example where parallel shield tunnels are very close to each other especially in poor cohesive soil ground. Accordingly, field measurements and in-situ measurements were performed to investigate the mechanism of ground behavior around pre-existing shield tunnel and its lining in case of later shield tunnelling. This paper aims to make clear the relationship between local earth pressure due to later shield tunnelling and cross-sectional forces especially bending moment of pre-existing shield segment rings, and to verify the authors' proposed pseudo-three dimensional numerical analysis method of segment rings based on the beam theory and the cylindrical shell theory in the longitudinal direction. As the result, we could propose the value distribution of local earth pressure during later tunnelling in use of the earth pressure type shield, and confirm to coincide almost with the measured bending moment and caluculated ones of the authors' method.
