3D large-deformation modelling on face instability and sinkhole formation during tunnelling through non-uniform soils. (April 2023)

• Record Type: Journal Article
• Authors: Chen, Xuejian; Hu, Yao; Zhang, Lei; Liu, Yong
• Is Part Of: Tunnelling and underground space technology. Volume 134(2023)
• Publication Date: 2023-04
• Subjects: Face stability -- Sinkhole formation -- Large-deformation modelling -- Spatial non-uniformity -- Probability of failure; c Cover depth of tunnel -- Cd Wave velocity of Euler material -- D Tunnel diameter -- E Young's modulus -- f Field variable -- H Depth at tunnel axis -- F Contact force between Lagrangian body and Euler element -- hmin Minimum mesh size -- k0 Initial geostatic stress factor -- ki Penalty stiffness coefficient in CEL method -- L Collapse distance of tunnel face -- Le Characteristic size of Euler element -- N Number of Monte Carlo simulations -- Nc Stability factor in uniform soils -- Nc ran, Stability factor in non-uniform soils -- p Probability of Failure -- P Critical support pressure in uniform soils -- Pran Critical support pressure in non-uniform soils -- S Source term in Eulerian formulation -- su Shear strength of non-uniform soil -- su0 Shear strength of uniform soil -- w Ground settlement -- γ Unit weight -- φ Friction angle -- Φ Cumulative normal function -- ψ Dilatancy angle -- ν Poisson's ratio -- ϕ Flux function -- uNc, ran Mean stability factor in non-uniform soils -- σNc, ran Standard deviation of stability factor in non-uniform soils -- usu Average undrained shear strength in non-uniform soils -- ΘH Correlation length in horizontal direction -- ΘV Correlation length in vertical direction -- Δx Displacement of anchor points punching through the Lagrange surface nodes in CEL method -- t Time step in CEL model -- Δtcrit Critical incremental step -- 2D Two-dimensional -- 3D Three-dimensional -- CEL Coupled Eulerian-Lagrangian -- COV Coefficient of variation -- EVF Eulerian volume fraction -- FEM Finite element method -- LFDE Large-deformation finite-element -- MPM Material point method -- SPH Smoothed particle hydrodynamics; Tunneling -- Periodicals; Underground construction -- Periodicals; Tunnels -- Periodicals; Underground areas -- Periodicals; 624.193
• DOI: 10.1016/j.tust.2023.105011
• Languages: English
• ISSNs: 0886-7798

Abstract

Highlights: Large-deformation modelling is conducted to study tunnelling-induced sinkhole. Spatial non-uniformity greatly affects face stability and sinkhole hazards. Deterministic analysis underestimates probability of failure of tunnel face. Consequence of sinkhole hazards is significantly underestimated in uniform soils. Abstract: Natural soils exhibit spatially non-uniform properties, bringing some uncertainties on the evaluation of tunnel stability. This study therefore investigates the face instability and in particular to the sinkhole formation in spatially non-uniform soils by conducting large-deformation finite-element (LDFE) analyses combined with a three-dimensional random field. The results from LDFE analyses indicate that soil spatial non-uniformity greatly affects the failure mechanism as well as the face stability. The stability factor in non-uniform soils is averagely smaller than the deterministic solution in a uniform soil, implying the assumption of uniform soil conditions likely underestimates probability of failure of a tunnel face. With regard to the sinkhole behaviour, the average ground settlement obtained from random analysis is greater than that from deterministic analysis. This underscores the necessity of considering the soil spatial non-uniformity in the analysis of the sinkhole behaviour. This study provides an improved understanding on the face stability and sinkhole formation during tunnelling through non-uniform soils.