Abstract:

Due to the advantages of large integral stiffness, easy installing and removing and high construction speed, steel sheet piles are widely used in the excavation of foundation pits. When the steel sheet piles are removed, however, voids may be created in the soil strata, which may cause cracks of the ground surface and the neighboring buildings. In this paper, the influence of 4 void widths, i.e., 40 mm, 100 mm, 150 mm and 200 mm, produced by steel sheet pile removing on the displacement and stressing of the existing tunnel and the ground surface settlement are analyzed by means of numerical simulation and on basis of study on the construction characteristics of the steel sheet piles. The results show that: 1) The displacement and stress of the existing tunnel increase as the void width increases. When the void width is 150 mm, the tensile stress increment is 4.65 MPa, which has exceeded the allowable tensile stress increment by 4.5 times; 2) The displacement and stress of the existing tunnel close to the steel sheet piles are much larger than those of the existing tunnel far away from the steel sheet piles; 3) The void produced by steel sheet pile removing has significant influence on the soil mass within the scope of 10 m around the void. In the end, countermeasures, including optimization of the steel sheet pile removing sequence, reducing the mud produced when steel sheet piles are removed, consolidation of surrounding soil mass and strengthening the monitoring, are proposed. The paper can provide reference for the protection of neighboring buildings when steel sheet piles are removed in similar soil conditions.

Key words: soft soil, steel sheet pile, removing, existing tunnel, numerical simulation