Investigation of geometric effects on three-dimensional tunnel deformation mechanisms due to basement excavation

Shi, Jiangwei; Fu, Zhongzhi; Guo, Weiwei

doi:10.1016/j.compgeo.2018.10.019

Cited by 83 publications

(30 citation statements)

References 33 publications

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“…First, apply the excavation-induced additional stress in the tunnel position calculated by Mindlin's solution to the constructed subway tunnel. Second, calculate the internal force and deformation in the constructed tunnel under the effect of the applied excavation-induced additional stress, by adopting the beam on elastic foundation theory [32,33]. The additional displacement method is also performed in two steps.…”

Section: Introductionmentioning

confidence: 99%

Predicting Response of Constructed Tunnel to Adjacent Excavation with Dewatering

et al. 2021

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This paper proposes a new method for predicting the displacement and internal force of constructed tunnels induced by adjacent excavation with dewatering. In this method, the total excavation-induced additional stress on the constructed tunnel is derived by superposing the additional stresses induced by excavation unloading and dewatering effects. The additional stress induced by unloading effect is calculated using Mindlin’s solution. The additional stress induced by dewatering effect is calculated using the principle of effective stress and the Dupuit precipitation funnel curve. With the beam on elastic foundation method, the total additional stress is then used for calculating the tunnel displacement and internal force caused by adjacent excavation with dewatering. Based on three well-documented case histories, the performance of the proposed method is verified. Moreover, a parametric analysis is also performed to capture the effects of excavation depth, tunnel-to-excavation distance, initial water level, excavation plan view size, and specific yield on the responses of the constructed tunnels. The results indicate that the effect of excavation depth on the tunnel maximum vertical displacement, maximum bending moment, and maximum shear force is more significant at an excavation depth greater than the cover depth of the constructed tunnel. The tunnel maximum vertical displacement, maximum bending moment, and maximum shear force decrease nonlinearly with an increase in the tunnel-to-excavation distance and the initial water level. Among the investigated parameters, the excavation dimension in the tunnel longitudinal direction affects most the tunnel responses. The effect of specific yield on the tunnel displacement and internal force induced by adjacent excavation with dewatering becomes more obvious as increasing the initial water level and excavation depth.

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Section: Introductionmentioning

confidence: 99%

Predicting Response of Constructed Tunnel to Adjacent Excavation with Dewatering

et al. 2021

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“…The deformation of adjacent tunnels as a result of basement excavation is such a typical problem in this kind of major engineering problems. To investigate the effect of tunnels due to a nearby basement excavation, numerous studies have been conducted using field tests [1][2][3][4][5], centrifuge model tests [6][7][8][9][10], and analytical and numerical methods [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

“…In order to investigate the influence of a basement excavation on the tunnel behaviour in dry sand precisely, Ng et al [8] carried out two centrifuge model tests to investigate this issue. Several numerical analyses based on these centrifuge model tests were conducted by adopting the hypoplasticity model for sand, and it was found that the hypoplasticity model can more effectively capture the soil behaviour compared with the previously reported centrifuge model test [9,16,18,19]. Mašín and Herle [30] developed a basic hypoplastic model to predict the clay behaviour at medium to large strain levels.…”

Section: Introductionmentioning

confidence: 99%

Tunnel Behaviour Caused by Basement Excavation in Clay

et al. 2021

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Many researchers have investigated the effect of basement excavation on tunnel deformation. However, the influence of consolidation on the interaction of basement-tunnel-soil is rarely considered or systematically studied in clay. In this study, three-dimensional coupled-consolidation finite element analyses were conducted to investigate the effect of consolidation on the tunnel response to excavation. An advanced nonlinear constitutive model was adopted, and numerical parametric investigations were conducted to study the effect of the excavation depth, tunnel stiffness, soil permeability coefficient, and consolidation time on the tunnel response. The results revealed that the basement excavation led to stress release, which caused tunnel heave. Owing to the dissipation of excess negative pore water pressure, the tunnel heave further increased to become approximately twice as large compared with that observed when the foundation pit excavation had just been completed. As the consolidation time increased, the longitudinal tunnel heave and tunnel diameter change caused by the foundation pit excavation gradually increased, but the growth rate was slower down. When the consolidation time changed from 50 days to 150 days, the maximum tunnel heave at the crown and the maximum tunnel diameter change increased by 1.18 and 1.48 times, respectively. The soil’s permeability coefficient did not have a significant effect on the tunnel heave at the crown nor on the tunnel diameter change. The results obtained by this study are expected to be useful as an engineering reference for the analysis of soil structure problems in clay.

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“…To sum up, the studies on spatially overlapping tunnels remain concentrated on the effects of tunnel excavation on the ground surface [7,[10][11][12][13], on the existing buildings [3,4], and on the existing tunnels [5,6,[14][15][16]. In particular, the studies cover the interactions between the following four systems: spatial arrangement between tunnels, tunnel geometric parameters, key technical parameters of tunnel construction, and engineering geological conditions.…”

Section: Introductionmentioning

confidence: 99%

Numerical Parametric Study of Countermeasures to Alleviate the Tunnel Excavation Effects on an Existing Tunnel in a Shallow-Buried Environment near a Slope

et al. 2020

Applied Sciences

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This paper studies the influence law of existing tunnels on the construction of intersecting new tunnels in a shallow slope burial context through 3D numerical analysis. The emphasis is on exploring the effect of new tunnels constructed in 54 conditions, including three ratios of overburden to tunnel height (C/H), three ratios of slope distance to tunnel span (D/W), two backfilling conditions of the existing tunnel (“hty” and “htn” conditions), and three magnitudes of surface loads (10 kPa, 20 kPa, and 30 kPa), on the deformation of lateral slopes and the overlying road. As the results show, the rigidly separated area between the existing and newly built tunnels in parallel to the excavation direction was precisely the sensitive area affected by the existing tunnel backfilling condition. The road settlement simulations perpendicular to the excavation direction revealed that various C/H and D/W ratio combinations controlled the shape and size differences of the settlement trough curve. This was because the C/H ratio primarily controlled the effective span and height transition of the newly built tunnel, whereas the D/W ratio mainly controlled the intersection position of the tunnels. Next, model A-A (“hty” condition) was identified as the only feasible construction model among all models in accordance with the engineering safety control criteria. Lastly, comparison of monitoring data with simulations found a slight difference in the distribution pattern between the two. Nevertheless, the final maximum settlement fully satisfied the construction control requirements overall. Aside from proving the correctness of simulation results, the present study also sets an excellent referential example for similar projects.

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Investigation of geometric effects on three-dimensional tunnel deformation mechanisms due to basement excavation

Cited by 83 publications

References 33 publications

Predicting Response of Constructed Tunnel to Adjacent Excavation with Dewatering

Predicting Response of Constructed Tunnel to Adjacent Excavation with Dewatering

Tunnel Behaviour Caused by Basement Excavation in Clay

Numerical Parametric Study of Countermeasures to Alleviate the Tunnel Excavation Effects on an Existing Tunnel in a Shallow-Buried Environment near a Slope

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