Abstract
Presented in this paper is a study on the lateral unloading creep tests under different excess pore water pressures. The marine sedimentary soft soil in Shenzhen, China, was selected in this study. The results show that the excess pore water pressure plays a significant role in enhancing the unloading creep of soft soil. Higher excess pore water pressure brings more obvious creep deformation of soft soil and lower ultimate failure load. Meanwhile, the viscoelastic and the viscoplastic modulus of soft soil were found to exponentially decline with creep time. A modified merchant model and a combined model of the modified merchant model and plastic elements are used to simulate the viscoelastic and the viscoplastic deformation, respectively. Therefore, a lateral unloading creep model of soft soil is developed based on the modified merchant model. The accuracy and applicability of this model were verified through identifying the parameters in the model. Research results are of particular significance to the numerical simulation of underground space excavation in soft soil areas which considers the effects of excess pore water pressure.
Highlights
Soft soil, being a special kind of regional soil with high water content, low bearing capacity, and salient creep characteristics, is widely distributed in Northern Europe, North America, and coastal areas of Pearl River Delta and Yangtze River Delta of China [1,2,3]
Excess pore water pressure = 21.2 – 56.12kPa creep constitutive models under loading were studied previously, and research results were applied to the numerical analysis of unloading excavation of the underground space in soft soil, resulting in a large gap between the calculated results and the actual situation [8, 9]. erefore, it had become a common practice among scholars to study unloading excavation of the underground space of soft soil by constructing the unloading creep constitutive model based on the unloading stress path
Excavation of the underground space in soft soil involves a variety of unloading stress paths, wherein the lateral unloading stress path plays an important role in the study of lateral deformation and stability of the underground space in soft soil [18]. erefore, this paper mainly focuses on the creep constitutive model under the lateral unloading stress path
Summary
Soft soil, being a special kind of regional soil with high water content, low bearing capacity, and salient creep characteristics, is widely distributed in Northern Europe, North America, and coastal areas of Pearl River Delta and Yangtze River Delta of China [1,2,3]. Erefore, the study of the constitutive model of unloading creep of soft soil under excess pore water pressure is of great significance to the numerical analysis and excavation optimization of underground space excavation in water-rich soft soil areas. E. Excess pore water pressure = 21.2 – 56.12kPa creep constitutive models under loading were studied previously, and research results were applied to the numerical analysis of unloading excavation of the underground space in soft soil, resulting in a large gap between the calculated results and the actual situation [8, 9]. Erefore, it had become a common practice among scholars to study unloading excavation of the underground space of soft soil by constructing the unloading creep constitutive model based on the unloading stress path. These unloading creep constitutive models take the anisotropy and structure of soft soil into account [11, 15], more unloading creep lies in the one-dimensional model, and further study of the triaxial unloading creep constitutive model of soft soil is needed
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