Numerical modelling of multiple excavations in an ultra-deep foundation using an enhanced distinct lattice spring model with modified cam clay model

The control of foundation deformation has garnered significant attention. This study focuses on understanding the deformation induced by excavation activities in real foundation construction scenarios. To accurately model the complex geomechanical responses, an enhanced Distinct Lattice Spring Model (DLSM) was developed. The Modified Cam Clay (MCC) model is employed to represent the nonlinear behaviour of the soil. Integration with one-dimensional structure elements is implemented to model support structures and their interactions with the soil. The birth-death particle method is utilized to simulate the excavation process of the foundation. To improve computational efficiency, a CPU-GPU heterogeneous parallel technique is employed. The enhanced DLSM produces consistent results with the finite element method when calculating foundation-bearing capacity and demonstrates relatively close results compared to finite difference methods when analyzing the stability of foundation slopes under different parameters. Finally, a three-dimensional numerical model is established using the proposed DLSM to simulate the deformation of the foundation caused by the excavations. The entire simulation task is divided into twelve stages, involving in-situ stress, a diaphragm wall, ten supporting structures, and ten excavations. A comparative analysis between the MCC model and the ZP (Zienkiewicz-Pande) model is conducted. The findings indicate that the calculation results of the two are consistent in the early stages of excavation, while those calculated by the MCC in the later stages are relatively small. Sensitivity analysis of the MCC parameters using orthogonal analysis reveals that the porosity of the soil has the greatest impact on the deformation of the foundation pit, followed by the slope of the swelling line, while the slope of the critical state line has a minimal impact. This work provides an alternative high-performance tool for engineering-scale deformation analysis of geotechnical underground excavation.