Abstract
The hardening soil (HS) model is the most commonly used constitutive models of soft soil of foundation pits of PLAXIS software in numerical analysis, and its parameters are prerequisite for accurate calculation. In this paper, relevant parameters of the HS model in Shenzhen Bay in China were studied through one-dimensional consolidation tests and triaxial shear tests. Analytical methods of reference secant stiffness and failure ratio of soft soil were systematically studied, the influence of shear rates on reference secant stiffness and failure ratio of soft soil was analyzed, and the relationship between stiffness parameters and compressive modulus of soft soil was established. The results showed that reference secant stiffness and failure ratio of soft soil obtained by different analytical methods were quite different, and the errors of reference secant stiffness and failure ratio of soft soil obtained by stress-strain curves were the smallest and the stability was the best; at the same time, with increase of shear rates, the peak deviator stress and reference secant stiffness of soft soil increased, but failure ratio did not change much. The research results could provide a reference of parameter analysis of soft soil for the HS model in the numerical analysis and similar working conditions of foundation pits.
Highlights
With rapid development of economy, more and more foundation pits adjacent to metro tunnels, metro stations, buildings, and municipal pipelines have been built in soft soil in coastal areas
It is difficult to analyze the influence of excavation of foundation pits on surrounding environment in soft soil reasonably by traditional analytical methods and relevant normative methods [1, 2]. e numerical analysis method has become the most effective method for excavation of foundation pits in soft soil because it can take into account the stratification and nature of soil, distribution and nature of support systems, construction process of excavation and support structures, and influence on surrounding environment [7,8,9,10]
E key point in numerical simulation is to adopt reasonable calculation parameters and constitutive models. e Mohr–Coulomb (MC) model, Duncan–Chang (DC) model, Drucker–Prager (DP) model, modified Cam–Clay (CC) model, cap model, and hardening soil (HS) model are commonly used in numerical simulation of excavation of foundation pits in soft soil [7,8]. e applicable conditions for different constitutive models of cemented clay and soft soil are shown in Table 1. e MC model is usually used in the rapid analysis of numerical simulation
Summary
With rapid development of economy, more and more foundation pits adjacent to metro tunnels, metro stations, buildings, and municipal pipelines have been built in soft soil in coastal areas. It is difficult to analyze the influence of excavation of foundation pits on surrounding environment in soft soil reasonably by traditional analytical methods and relevant normative methods [1, 2]. E numerical analysis method has become the most effective method for excavation of foundation pits in soft soil because it can take into account the stratification and nature of soil, distribution and nature of support systems, construction process of excavation and support structures, and influence on surrounding environment [7,8,9,10]. E Mohr–Coulomb (MC) model, Duncan–Chang (DC) model, Drucker–Prager (DP) model, modified Cam–Clay (CC) model, cap model, and hardening soil (HS) model are commonly used in numerical simulation of excavation of foundation pits in soft soil [7,8]. When soft soil has shear-softening effect, yield surface with cap shape is suitable, such as DP model, modified CC model, and cap model [11,12,13], among which, the HS model can consider hardening characteristics of soft soil and distinguish the difference between loading and unloading, and its stiffness parameters depend on stress history and stress path; its Advances in Materials Science and Engineering
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