Large deformation analysis in geohazards and geotechnics

For geohazards and geotechnics, numerous problems involve large deformation, such as the installation of foundations (Jin YF et al., 2018a), landslides (Jin YF et al., 2020b), debris flow (Dai et al., 2017), collapse of underground structures (Zhang et al., 2019), and the formation of sinkholes (Barandiarán Villegas, 2018). Benefitting from the sustained development of computing power, numerical simulations have become useful analytical methods in geomechanics and related fields. Among those numerical methods, the finite element method (FEM) features prominently in engineering practice (Rao, 2017). For conventional FEM, however, excessive deformation may result in mesh distortion with numerical inaccuracy, even to the point of making calculation impossible. To solve this issue and enable application to large deformation analysis, different numerical approaches have been successfully developed. These approaches can be generally classified into three categories: discontinuous, continuous, and coupled continuous– discontinuous (Zhang, 2014). One of the most popular discontinuous approaches is discrete element method (DEM) (Cundall and Strack, 1979; Calvetti, 2008). Practical applications of this kind of method are limited by their high computational cost, although their robustness and potential have been demonstrated in academic exercises. Continuous approaches can be sub-divided into three groups: (1) mesh-based methods, such as the arbitrary Lagrangian–Eulerian (ALE) (Belytschko et al., 2013) and the remeshing and interpolation technique with small strain (RITSS) (Hu and Randolph, 1998); (2) mesh-free particle methods, such as the smoothed particle hydrodynamics (SPH) method (Lucy, 1977), element-free Galerkin (EFG) method (Belytschko et al., 1994), and reproducing kernel particle method (RKPM) (Chen et al., 1996); (3) mesh-based particle methods, such as the material point method (MPM) (Harlow, 1964) and particle finite element method (PFEM) (Oñate et al., 2004; Zhang et al., 2013) and its variants-strain smoothed PFEM (Zhang et al., 2018; Yuan et al., 2019; Jin YF et al., 2020a, 2020b, 2021a, 2021b; Guo and Yang, 2021; Meng et al., 2021). The coupled Eulerian–Lagrangian (CEL) is another mesh-based method (Qiu et al., 2011; Hamann et al., 2015), similar to MPM, and requires a background mesh. The third category of methods used for large deformation analysis, the coupled continuous–discontinuous approach, includes finite difference method (FDM)-DEM (Yin et al., 2020), PFEM-DEM (Guo et al., 2021), and MPM-DEM (Liang and Zhao, 2019). Significant developments have been made in this field, which has attracted more attention in recent years due to consideration of the physics of geomaterials. This special issue contains original research articles on the application of numerical methods to large deformation analysis of geohazards and geotechnics. Focal points of the issue include innovative uses of: (1) mesh-based methods, (2) mesh-free particle methods, (3) mesh-based particle methods, (4) discontinuous numerical methods, and finally (5) practical applications of the above techniques, e.g. case studies and benchmarking exercises. We invited prestigious scientists in the field to share their expertise and perspectives. The collected Editorial: Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering) ISSN 1673-565X (Print); ISSN 1862-1775 (Online) www.jzus. zju.edu. cn; link.springer. com E-mail: jzus_a@zju.edu. cn