Abstract
Double-O-tube shield tunneling has attracted increasing attention because it offers cost-efficiency in underground construction. Prediction of ground surface settlement and the variety of additional stresses induced by shield construction is crucial to underground construction in metropolises since excessive settlement could trigger potential damage to the surrounding environment. The additional stresses induced by the propulsion of double-O-tube shields are calculated by means of the Mindlin’s equations of elasticity. The characteristics of additional stresses are analyzed with compound Gauss-Legendre integral arithmetic, and the frontal additional thrust, the lateral friction, and the ground loss are taken into account. Subsequently, based on field measurements, the maximum settlement coefficient and width of the settlement trough coefficient of the typical Peck formula are modified. The predictive curve of the Peck formula is closer to the engineering measured data than that of the typical formula. The cut-off functions of ground surface settlement caused by double-O-tube tunnel shield construction are proposed and can predict the shape of ground surface settlement, such as single peak or double peak. The correctness of the proposed functions is verified based on an engineering project.
Highlights
With the rapid development of urban construction, a series of problems has been caused because of heavy transportation systems and a lack of public space in the metropolises [1,2]
1) Along the direction of shield excavation, the additional stress over the peak value at a range of 1.3 D ~ 1.67 D from the tunnel face
1) Along the direction of shield excavation, the additional stress over the peak value at a range of 1.3 D ~ 1.67 D from the tunnel face gradually diffuses to both ends
Summary
With the rapid development of urban construction, a series of problems has been caused because of heavy transportation systems and a lack of public space in the metropolises [1,2]. The five main research topics are as follows: (1) to give the calculation of frontal additional thrust and friction between the shield shell and the soil; (2) based on Mindlin’s solution of elasticity, frontal additional thrust and friction between the shield shell and the soil and ground loss are considered to investigate the stress distribution characteristics of the soil around double-O-tube shield tunneling after excavation; (3) the Peck formula is modified to better predict the ground surface settlement compared with the typical Peck formula for a sand layer; (4) the settlement pattern of the tunnel, the influence of the burial depth and the spacing, and the soil parameters on the surface settlement curve are studied based on three-dimensional finite element models; (5) the cut-off function’s predicted shape of the surface settlement curve, such as single and double peaks, is proposed
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