Analysis of longitudinal deformation of existing rectangular pipe jacking tunnel caused by shield tunnel undercrossing

Abstract

The existing rectangular pipe jacking tunnel is prone to deform after the construction of the new nearby shield tunnel, resulting in longitudinal uneven settlement, water leakage, and other ailments that could jeopardize the structure’s safety. The safety of the existing rectangular pipe jacking tunnel is in jeopardy in order to prevent the excessive deformation of the tunnel following the construction of the new shield tunnel. This paper proposes the foundation stiffness function model and SP-T model to describe the settlement curve of the new shield tunnel to the existing rectangular pipe jacking tunnel using the first phase project of Hohhot Rail Transit Line 2 in Inner Mongolia as an example. The model is more coincidental than the original Pasternak-Timoshenko model considering the distribution in soil caused by the excavation of a new tunnel because it takes into account the change in foundation stiffness based on the Pasternak foundation. The findings demonstrate the consistency between the field data results and the prediction results derived from the analysis method presented in this paper. The further parametric study examined some influences on the construction of a new shield tunnel that affects already-existing pipe jacking tunnels. These studies include equivalent longitudinal bending and shear stiffness, as well as the location and angle of the new tunnel in relation to the existing rectangular pipe jacking tunnel. In addition to highlighting the impact of equivalent shear stiffness on the existing rectangular pipe jacking tunnel, the impact of equivalent longitudinal bending stiffness and equivalent longitudinal shear stiffness on settlement is discussed in the article. This paper’s research methodology can not only forecast the new shield tunnel’s longitudinal settlement deformation beneath the existing rectangular pipe jacking tunnel, but it can also generate fresh concepts for investigating related issues.