Influences of Subsoil Modelling on Underground Deep Excavation Behaviour in Phnom Penh City, Cambodia

Due to the rapid growth of businesses and the population in Phnom Penh City, Cambodia, deep excavations for underground spaces are an economic necessity for landscape aspects. Several studies have been conducted on deep excavation and constitutive soil models in numerous Southeast Asian countries. However, there is limited information regarding (little knowledge available on) soil characteristics and subsurface conditions for excavation projects in Cambodia. This study uses 3D finite element analysis (FEA) to model a contiguous bore pile excavation with a bottom-up construction method located in Phnom Penh City sedimentary deposit. Site investigation, including field and laboratory tests, was conducted. Phnom Penh subsoils of the study location were modelled by Mohr–Coulomb, hardening soil and soft soil models. The model parameters were calibrated against triaxial and oedometer tests at the site. The 3D FEA were simulated to determine the lateral wall movement and ground surface settlement by comparing with the field monitoring data and empirical predictions. In Phnom Penh City, the clay layer mainly consists of three types of clay: medium clay, soft clay, and stiff clay. This exhibit is similar to alluvial deposits reported in other Southeast Asian cities. Based on the results of the analysis, the numerical simulation findings from various soil models are consistent with inclinometer data and empirical predictions. The simulations employing the hardening soil model show better results than those using the Mohr–Coulomb and soft soil models.