Numerical Analysis Of Existing Pile Due To Excavation

With the development of city, excavation has been one of the important geotechnical engineering. However, excavation engineering tends to be constructed in impacted area. Engineers need to not only guarantee the stability of excavation but also control the distortion of excavation so as to protect the safety of building, structure and subterranean line. The deformation characteristic of piles nearby excavation is different from the typical active pile, which belongs to typical passive pile, because of the soil movement due to excavation. It is thus important for practicing engineers and scholars to be able to estimate the construction impact on adjacent piles during excavation. Therefore, the studies are emphasized on numerical methods for the effects of excavation on a single pile nearby excavation. The main investigations consist of the following two parts:1. An elasto-plastic total stress finite-element computational model is established in two dimensional space to study pile response due to excavation-induced soil movement on the basis of the general-purpose finite element software ABAQUS. And the soil is assumed to be a uniform normally consolidated clay layer. Influences of various parameters on pile response including undrained shear strength of soil, depth of excavation, elastic modulus of knee wall, strut stiffness, pile diameter, and distance from excavation face are investigated. The results indicate that the excavation-induced soil movement is critical for adjacent piles. Improvement of the strength of clay foundation and bracing system is helpful to control the distortion of piles.2. In plane strain state, by coupling 2-D Biot consolidation theory and modified cam-clay model, as well as using Coulomb contact pair theory to simulate contact behavior between soil and structure, an elasto-plastic effective stress finite-element computational model is performed and then effects of several parameters on the behavior of pile subjected to excavation-induced soil movement is investigated with specific attention being focused on braced excavation in uniform clay layer on the basis of the general-purpose finite element software ABAQUS. The results reveal that after the completion of soil excavation, the knee wall and the surrounding soil continue to move and such movement induces further deflection on an adjacent pile. The pile movement increases with increasing excavation depth and reaches its maximum value sometime after soil excavation and thereafter decrease with time.