Effects Of Shield Tunneling On Movements And Internal Forces Of Adjacents Pile Foundations

With the development of urbanization, the importance of subway is revealed gradually in many cities, especially those facing a problem with traffic. In urban areas, tunnel construction which generates ground displacements and deformations can effect the preexisting buildings and main services and could lead to unacceptable damages. And many high-rise buildings are supported by pile foundations. However, ground movement induced by tunneling will unavoidably exert the effect on the adjacent pile foundations. So it is significant to research the effects of tunneling on adjacent pile foundations.In this paper, the author firstly summarizes the existing circumstance of the ground movements and adjacent pile responses induced by tunneling. Secondly, a brief introduction is made about theories of constitutive models, pile foundations, and ground movements. Then, a numerical test model is built to simulate the construction of shield tunneling. In this model, many details are included, such as the process of construction, grouting materials and pressure, the interface between pile, lining and soils. And the validity of this model is verified by comparison of numerical test results between this model and centrifuge model tests.On the basis of the exactness of this model, the behavior of pile movements and internal forces is researched after tunnel excavation by systemic numerical tests. Firstly, the effects of shield tunneling are made on single friction pile and double pile. In this analysis of single pile, many factors are considered, namely the horizontal distance from piles to tunnel centre, pile end position regarding to horizontal tunnel axis, different modul ratio of pile to subsoil, grouting pressure. In the analysis of double pile , the comparison of response of the group elements to that of single piles located at equal horizontal distance from the tunnel centre is made. Secondly, the effects of shield tunneling on end bearing single pile and double pile are talked about. And the comparison of response of friction piles to end bearing piles is made. Lastly based on the numerical test results with different horizontal distance from tunnel centre, pile end position, modul ratio of pile to subsoil, different bearing mechanism, the quantificational law of the effects of bearing capacity on adjacent pile induced by shield tunneling is summed up.