Abstract：Construction of tunnels in urban area requires assessment of the effect of tunneling on the stability and integrity of existing pile foundations. This paper discusses the bearing capacity of pile-foundation under the effect of construction of metro tunnels adjacent to pile foundations based on the engineering background of the construction of No. 2 Line of Guangzhou Metro in China. The fast Lagrangian analysis of continua is used to simulate the response of piles under the complete process of metro tunneling(deactivation of soil element and activation of the lining). The adjacent rock around the tunnel is classified into three regions：Region I (upper adjacent stratum of tunnel)，Region II (45°-upper-lateral adjacent stratum of tunnel)，and Region III (lateral adjacent stratum of tunnel). In each region one typical pile is chosen to calculate and analyses in detail. Numerical simulations are performed concerning，respectively，side-friction force of pile，tip resistance of pile and pile axial loading. Contrasting analyses are performed both in the response of typical piles in different regions，and in computer calculating value with field measuring value. Results of numerical simulations show that the effect on the carrying capacity of pile lies mainly in the effect of construction metro tunnels on the side-friction force and the tip resistance of pile. The effect is widely different from stratum to stratum where the pile tip is located at. The complicated rules of side-friction force and tip resistance of pile result in the complicated rules of pile axial loading，thus it influence the carrying capacity of pile-foundation at last. It is necessary to take positive measures，such as stratum grouting stabilization or foundation underpinning，etc.，to deal with the carrying capacity and the settlement of pile-foundation. The results are valuable for similar engineering projects.
