Abstract
Earth pressure balance or slurry shield tunnelling will squeeze the subsoils and lead to lateral outward ground displacement. However, current methods to estimate the shield tunnelling-induced ground displacements generally use the methods based on the face unsupported tunnelling (e.g., New Austrian tunnelling and open shield excavation), which cannot predict the lateral ground movement due to shield tunnelling. In this paper, a novel simplified analytical method is proposed to predict the ground lateral displacement during the shield advancing process. The key shield tunnelling operation factors, including the additional pressure of cutter head, the friction forces around shield body, the back-fill grouting pressure, and the soil volume loss are all considered. The lateral ground displacements induced by the four former factors are calculated by using Mindlin’s solutions. The soil volume loss-induced lateral ground displacement is calculated by employing the expression introduced by Pinto and Whittle. Combining with the displacement obtained from all the factors, the analytical method for lateral ground displacement induced by shield tunnelling is obtained. The applicability of the proposed analytical approach is verified with three well-documented case histories involving slurry shield and EPB shield machines.
Highlights
Earth pressure balance (EPB) or slurry shield tunnelling technology has advantage of rapid construction efficiency and minor environment disturbance, which is widely used in metro tunnel construction in densely urban area
E ground movement mechanisms associated with shield tunnelling are totally different from the face unsupported tunnelling, such as New Austrian tunnelling and open shield excavation, in which the inward ground movements are usually observed because of none face pressure or grouting pressure imposing on the excavation face
Bobet [8] and Osman et al [9] deduced a series of solutions for two-dimensional soil movements based on the elasticity theory. e abovementioned analytical solutions are more suitable for estimating the ground movement associated with face unsupported tunnelling
Summary
Earth pressure balance (EPB) or slurry shield tunnelling technology has advantage of rapid construction efficiency and minor environment disturbance, which is widely used in metro tunnel construction in densely urban area. A novel simplified analytical method is proposed to predict the lateral ground displacements caused by shield tunnelling in soft ground. E key shield tunnelling operation parameters such as additional pressure of cutter head, the frictions around shield shell, the grout injection pressure, and the soil volume loss are taken into account in the proposed method to consider the shield tunnel construction performance. 2. Simplified Analytical Method for Predicting Lateral Ground Movement Induced by Shield Tunnelling e mechanism of the interaction between shield tunnelling excavation and soil surrounding is highly complex. E ground deformation is mainly influenced additional pressures of cutter-head q, frictions around shied shell skin f, the tail grouting pressure p, and the soil volume loss vl during shield machine advancing. E response of lateral displacements at both longitudinal and transversal directions to the horizontal concentrated force Ph is expressed as follows: vh
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