Two-phase PFEM with stable nodal integration for large deformation hydromechanical coupled geotechnical problems

The node-based strain smoothed particle finite element method (NS-PFEM) has a high level of computational efficiency. However, it has not yet been extended to hydromechanical coupling. This study presents the development of a two-phase one-point stable NS-PFEM (SNS-PFEM) for solving large deformation hydromechanical coupled geotechnical problems. First, the soil–water coupling is achieved by the v–w formulation based on Biot's mixture theory, which automatically ensures the consistency between water pressure and stress that the former should be interpolated one order lower than that of velocity. Secondly, the node-based strain smoothing method with linear strain fields over the smoothed domain on 3-node triangular elements is adopted and implemented to obtain a stable nodal integration. Thirdly, a novel efficient water pressure stabilisation scheme based on an inverse distance interpolation algorithm is implemented to cure spurious spatial water pressure oscillations. The performance of the hydromechanical SNS-PFEM is primarily validated by both static and dynamic 1D consolidation and 2D wave propagation, and then applied to analyse the progressive landslide and the Selborne cutting slope involving large deformation. All results demonstrate that the proposed method is powerful and easily extensible for analysing large deformation hydromechanical problems in geotechnical engineering.