numerical analysis of soldier piles construction to reduce surface settlement due to tunneling

urban development and rapid expansion of cities over the past decades have been accompanied by a considerable growth in mechanized tunneling. the construction of shallow tunnels of large diameter leads to the ground movement which could adversely affect the abutting structures. excessive vertical and horizontal displacements pose a major threat to these structures. preventive measures such as diaphragm walls and a row of soldier piles can effectively protect adjacent structures from possible damages. this research specifically assesses the effectiveness of a simple row of soldier piles by three-dimensional simulation with finite difference approach. moreover, the relationship between the performance and major geometrical parameters such as spacing among the piles, distance from tunnel axis and piles length in greenfield condition are investigated. the simulation results show a strong relation between the length of piles and displacement reduction. piles should be founded at least half a tunnel diameter below the invert and in all cases, a row of piles perform better when the space among them is low.