Abstract
Based on the granular-solid-hydrodynamic theory, the constitutive model considering the thermo-hydro-mechanical (THM) coupled action is established, and the dilatancy property of sandy soil under coupled high mechanical pressure and temperature is simulated. The relationship between the energy dissipation and the macroscopic stress-strain changes at the grain level of saturated sandy soil is connected by defining the transfer coefficient and the energy function, without considering the concepts of yield surface and hardening parameters in classical plastic mechanics. Additionally, the changes in temperature, relative density and confining pressure during the shearing process cause particle rolling, slipping and friction. The energy dissipation in this process is described by defining the concept of particle entropy and particle temperature. In the calculation, the isotropic compression test, drained and undrained shear test of sandy soil under high stress are simulated respectively. The validity of the model is proved by comparing with the test results. Meanwhile, the stress-strain relationship and pore pressure variation law of sandy soil under different temperatures are predicted. The results show that the effect of temperature on shear strength is limited, and the pore pressure will gradually increase and become stable with the increase of temperature. Thus, this work establishes the soil THM coupled model from the perspective of micro energy dissipation, which can provide new theoretical support for the prediction of natural disasters such as landslides and debris flow.
Highlights
In mountainous areas, under the action of high ground stress, water flow and temperature, sandy soil will be disturbed by the construction of gravity dams, deep-buried tunnels and other large-scale projects, which will generate pore water pressure in the sandy soil, and cause particles to roll or even break (Bai et al, 2014; Wang et al, 2021)
The results show that when the confining pressure exceeded 12 MPa, FIGURE 2 | Stress-strain relationship and model prediction results of triaxial undrained shear test on dense sandy soil
By introducing the state variable into the dilatancy equation and using the theory of GSH and critical state, an inelastic coupled model of thermo-hydro-mechanical is established without considering the concepts of yield surface and flow rule, and the characteristics of sandy soil under the action of high stress and temperature are simulated
Summary
Under the action of high ground stress, water flow and temperature, sandy soil will be disturbed by the construction of gravity dams, deep-buried tunnels and other large-scale projects, which will generate pore water pressure in the sandy soil, and cause particles to roll or even break (Bai et al, 2014; Wang et al, 2021). Using the definitions of particle entropy and particle temperature, Jiang and Liu (2009) established the theoretical constitutive model of single granular material, which can comprehensively consider the macro and micro behaviour of granular material On this basis, some researchers (Zhang and Cheng, 2017; Bai et al, 2019a) extended the GSH theory to saturated soil and unsaturated soil, respectively, to simulate the mechanical characteristics of related soil, which confirmed the effectiveness of the model. In the present study, based on the GSH theory and the dilatancy equation considering the state variables, a THM coupled model is established, and the shear test of saturated sandy soil under the coupled action of temperature and stress is simulated. At the same time, based on undrained test, the stress-strain relationship and pore pressure change of sandy soil under different temperatures are predicted, which provides a reference for the development of follow-up experiments
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