Modeling loess collapsibility using oedometer tests for foundation and pile settlement prediction

To enhance the construction foundation safety in the loess regions of Northwest China, this study systematically investigated the collapsibility characteristics of loess from a construction site in Lanzhou through laboratory collapse tests under constant pressure. Regression modeling was employed to quantitatively evaluate the influence of key geotechnical parameters-including natural density, dry density, moisture content, void ratio, and compression modulus-on the collapsibility coefficient. Significant relationships were established between the collapsibility coefficient and void ratio, natural moisture content, and compression modulus. Furthermore, the standard method was used to determine the variation of potential collapse around piles with depth, revealing an exponential distribution trend. It is worth emphasizing that this study successfully developed an exponential function model based on easily obtainable parameters (natural density, dry density, moisture content, and compression modulus) for quantitatively predicting the collapsibility coefficient. In contrast to existing models, which often rely on single indicators and lack a multi-parameter collaborative evaluation system-resulting in limited engineering applicability-this study integrated five parameters to construct a comprehensive prediction model, filling the gap in multi-index evaluation systems. This model provides a practical tool for more accurately predicting loess collapse settlement and can be directly applied to risk assessment and mitigation design for building foundations and pile-soil interactions in similar loess environments in Northwest China.