Reducing the Tunnelling Effect on Adjacent Pile Foundations

Tunnel excavation may induce adverse effects on nearby existing structures/foundations in urban areas. Jet grouting is used as solution in the influenced area near or around the tunnel vicinity to reduce the induced stress and deformation of tunnelling process on nearby deep foundation. The objective of the present study is to numerically evaluate the nature of interaction between the employed tunnelling technologies; the nearby structures founded on deep foundation systems and grouted soil using 3D finite element idealization. Back analysis of The stability of El-Attabe Garage building due to the execution of the Greater Cairo Metro Line 3-Phase 1 is conducted in this paper to evaluate the capability of the proposed numerical model. Also, in the present study, a parametric study is conducted using a 3D finite element code to investigate the effect of the different grouting shapes such as jet grouting wall placed at or below tunnel springline, to reduce the tunnelling effect on adjacent pile. In addition, another shape of circular annuals grouting is investigated in this paper. Accordingly, the upper half and full annulus of soil region around the tunnel is grouted before tunneling process to enhance the soil properties and decrease the effect of tunneling. These grouting annuls have a same thickness and length as that of grouting wall used behind the pile. All of these schemes of grouting shapes are used to study their effect on reducing the pile response due to tunnelling process.