Prototype Model Tests of Soil and Tunnel Interactions under Earthquake Forces

This paper presents test results of a prototype model of soil and metro tunnel interaction on a 1/40 scale in laboratory. The horseshoe-shaped metro tunnel model was mounted on a shaking table to induce earthquake forces for simulating the seismic activities in the Xi'an metro system. The effects of fault lines (in the form of ground fissures) on the soil-tunnel interaction were also investigated. The seismic response data including the acceleration, displacement and dynamic soil pressure between the tunnel and soil, were measured to test the scale model. The test results conclude that 1) the tunnel-soil interaction had significant influence on the bulk dynamic response of the system; 2) the soil pressure and the acceleration changed with the seismic inputs. The soil pressure at the top of the tunnel increased while the pressure at the bottom decreased; 3) the acceleration of the tunnel was greater than that of the adjacent soil; 4) the soil settlements within the vicinity of the fissure were larger as compared to the settlements further away from the fissure.