دانلود رایگان مقاله انگلیسی راه حل ساده برای تعامل تونل-خاک-شمع در مدل پی پاسترناک - الزویر 2018

ABSTRACT

The current design practice for predicting the interaction mechanics for tunnel-soil-pile is generally based on Winkler’s foundation, which is subject to some important limitation, such as ignoring the continuity of the soil foundation. Furthermore, the current analytical studies are mostly employed the plane strain analyses and do not consider the influences of lateral soil displacements on pile behaviour. To improve the accuracy for the pile behaviour prediction induced by tunnelling, the analytical method should account for the effects of a number of parameters, such as the ground shearing displacements, and the influence of lateral soil displacements next to the pile. This paper focuses on a simplified solution based on Pasternak’s foundation model to predict the lateral displacements and internal forces of a single-pile and group-piles induced by tunnelling considering the effects of lateral soil displacements. First, the simplified solution of tunnel-soil-pile interaction, which reflects the influence of shearing displacements of foundation, is established on Pasternak’s foundation model. Second, the equivalent concentrated forces are supplied to the pile through the shear layer to consider the influence of lateral soils beside the pile. The validity of the solutions is verified by the boundary element program results, centrifuge test data, and field measurements. The calculated results are also compared with and without considering the effects of tunnel-soil-pile interaction. When the influences of lateral soil displacements are considered, the results are shown to be closer to the monitored in-situ data and the centrifuge test data. In addition, the influencing factors of a single-pile and group-piles displacements are also investigated, including the shear layer modulus, pile diameter, ground-loss ratio, pile-tunnel distance, and pile spacing. The influence of soil shear displacements on pile response cannot be ignored, and an error may occur when Winkler’s foundation model is used to solve this problem.

6. Conclusions

To avoid the drawbacks of the plane strain analyses and Winkler’s foundation, this paper addresses the influence problem of tunnel-soilpile interaction, and a simplified method is proposed based on Pasternak’s foundation model. The analyses aim to provide an efficient means to assess the effects of tunnelling on the lateral displacements and bending moments of an adjacent single-pile and group-piles. The pile response induced by tunnelling is presented firstly based on Pasternak’s foundation model considering the shearing displacements of foundation. To obtain more accurate results, the simplified solution is derived secondly considering the effect of lateral soil displacements. The response of a single-pile is determined by imposing the free-field soil movement profile estimated by Loganathan-Poulos’ analytical expression to the passive pile based on Pasternak’s foundation model. The shielding effect of passive group-piles due to pile-soil-pile interaction is then considered, and Mindlin’s solution for the lateral response is adopted to simulate the pile-pile interaction. The responses of grouppiles due to tunnelling are finally obtained by the superposition principle. The proposed method is verified through comparisons with published solutions by the boundary element program GEPAN, centrifuge test data and field measurements. The displacements and bending moments of a single-pile and group-piles induced by tunnelling are calculated through the presented method considering the effects of lateral soil displacements.