Effect of repeated shear deformation on twin tunneling - model test and finite element analysis

摘要

Number of parallel tunnels is increasing day by day to meet the demand of modernization. Duringrnearthquake soil is experienced with shear deformation due to ground excitation. Therefore, it is necessary torncheck the behavior of twin tunneling during and after earthquake for a safe and secured tunnel construction. In thisrnresearch, behavior of twin tunnels during the application of repeated shear deformation has been investigatedrnwith a new tunnel device. The device consists of two model tunnels which are free to move along with thernsoils of the ground. Here, several tests are conducted changing the position of following tunnel. In the tests,rnrepeated shear deformation is applied in the ground through the application of horizontal inertial force afterrnthe completion of twin tunnels excavation. Earth pressure of the tunnels are measured during the application ofrnshear deformation. The corresponding non-linear finite element analyses are also conducted using FEMtij-2Drnprogram where elastoplastic subloading t_(ij) model is used as a constitutive model of soil. From the model testsrnand numerical simulations it is found that the earth pressure around the tunnels changes significantly accordingrnto the direction of the repeated shear.