ABSTRACT
The mechanized tunneling method, such as tunnel boring machine, is considered as a sound means of excavation which does not significantly damage the surrounding ground or rock. However, based on recent studies and analysis, the mechanized tunneling method also induces notable range of excavation damage zone. The damages around the excavation surface can be classified based on the degree of damage done on the surrounding ground or rock - excavation influence zone (EIZ), excavation damage zone (EDZ), highly damage zone (HDZ) and construction damage zone (CDZ). The damage on the surrounding ground or rock can changes the mechanical properties of the ground, weaken the bearing capacity and lower the structural stability of underground structures, such as pile foundations. In this study, an intensive three-dimensional large deformation analysis will be carried out to investigate the effect of various types of excavation damage zone on nearby pile foundations. The excavation damage zones will be classified based on the ratio of deviatoric stress to original ground’s unconfined compression strength (UCS) induced during excavation process - over 10% will be designated as EIZ, 30% to 50% will be considered as EDZ, and when the deviatoric stress exceeds 50% of the ground’s unconfined compression strength it will be assumed as HDZ. Under these damages, changes in lateral and axial behavior of pile foundations will be estimated and analyzed. The numerical results clearly show that, the higher the ground damage occurs, the lateral displacement and settlement of the pile foundation was also found to increase significantly. However, in case of the EIZ, the changes were insignificant.
