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Pore water chemistry can exert significant controls over the chemo-mechanical behavior of chemically active soils, which has not been characterized by using the traditional Terzaghi's effective stress to a satisfactory extent. In this paper, based on the concept of intergranular stress, a generalized effective stress for saturated active soils is reconceptualized and incorporated into the framework of the modified Cam–Clay (MCC) model to describe the mechanical response of soils upon complex chemical and mechanical loadings. The proposed model is capable of capturing very well the diverse features of the chemo-behavior of saturated active soils, while inheriting all the advantages of the MCC model, by introducing only one additional parameter. Within this context, a simple equation is derived to predict the development of swelling pressure with the variation of pore water chemistry. It is shown that the proposed swelling-pressure equation predicts very well the development of swelling pressure for expansive soils with a dilute pore solution, though discrepancy appears at high concentration. Because the double layer of clay particles is severely suppressed at high salt concentration, the microfabric of soil can be significantly changed, pointing to the importance of taking into account the effect of soil fabric in the constitutive modeling of active soils with high pore water concentration. [ABSTRACT FROM AUTHOR]

There are relatively few experimental studies on the hydromechanical and critical state behaviours of unsaturated silty sand. In this paper, suction-controlled, consolidated, drained triaxial shear tests were conducted on silty sand under saturated (net confining pressures of 100, 200, 300 and 400 kPa) and unsaturated (suctions of 30, 100 and 200 kPa and net confining pressures of 100, 200 and 300 kPa) conditions. For unsaturated silty sand, the effects of dry density, matric suction and net confining pressure on the hydromechanical and critical state behaviour were investigated, and the critical state parameters were obtained. The main findings for unsaturated silty sand included shear shrinkage at low dry density (1·6 g/cm3) and dilatancy at higher density (1·96 g/cm3). The peak shear strength was positively correlated with dry density, matric suction and net confining pressure. The critical state volumetric strain and critical state degree of saturation were negatively correlated with dry density and matric suction but positively correlated with net confining pressure. A new dilatancy equation that includes the state parameter for unsaturated silty sand was established. A unique critical state line passes through the origin in the effective stress p ∗ –deviator q plane, and its slope is the saturated critical state stress ratio M s . In the lnp*–v plane ( v is the specific volume), the critical state lines corresponding to different matric suctions are parallel. [ABSTRACT FROM AUTHOR]

Loess is usually compacted as building filler in geotechnical engineering construction and the wetting-induced deformation characteristics of compacted loess are closely related to engineering safety. The influence of hydromechanical paths on compacted loess wetting-induced deformation characteristics has been rarely addressed in the literature, especially for compacted sandy loess. In this study, the scanning electron microscopy (SEM) and soil–water retention curve (SWRC) tests are performed to investigate the microstructure and water retention characteristics of compacted sandy loess. Single-oedometer triaxial wetting tests with three complex hydromechanical paths (consolidation-wetting under isotropic stress state, consolidation-loading-wetting-loading and consolidation-unloading-wetting-unloading under deviator stress) are carried out on unsaturated compacted sandy loess. Results indicate that: (1) As the dry density increases, the large inter-aggregate pores inside the compacted sandy loess turned into medium inter-aggregate pores and small inter-aggregate pores; the air entry value increases and the water retention capacity is enhanced. (2) Within a certain range of confining pressure (no more than 400 kPa), the wetting volumetric strain increases with the increase in confining pressure and dry density under isotropic stress condition; the loading paths wetting-induced deformation is greater than unloading paths wetting-induced deformation under deviator stress condition. (3) At a lower stress ratio, compacted sandy loess undergoes significant wetting-induced dilatancy; the wetting-induced deformation under the unloading path appears significant, compared with that under the loading path. [ABSTRACT FROM AUTHOR]

Focusing mainly on the compressive-shear (C-S) stress, the existing soil strength theories fail to well describe the soil strength under tenso–shear (T-S) stress and are not suitable for analyzing the tensile strength and T-S coupling strength. Taking the T-S strength into account, a three-dimensional nonlinear strength model of soil is established. The failure function on the π plane is a Lade Lade-curved triangle in principal stress space, which reasonably reflects the effect of medium principal stress. The failure function on the triaxial compression meridian plane is divided into the T-S and C-S zones, in which the two failure functions are smoothly connected at the closed stress point. To easily combine it with the specific elastoplastic constitutive theory, the proposed strength model is transformed into the D-P criterion in transformed stress space using the transformation stress method, which provides a theoretical foundation for numerical calculations. Compared with the true triaxial test results and numerical slope examples, the proposed model gives a good description of the nonlinear soil strength under complex stresses and the instability failure mechanism of the slope. [ABSTRACT FROM AUTHOR]

We study the nonreciprocal excitation and entanglement dynamics of two giant atoms (GAs) coupling to a one-dimensional waveguide. With different positions of coupling points, three configurations of two separate GAs, two braided GAs, and two nested GAs are analyzed, respectively. The coupling strengths between different coupling points are considered as complex numbers with phases. For each coupling configuration, the nonreciprocal excitation dynamics and entanglement properties, which results from the phase differences of coupling strength and the phase induced by photon propagation between the two coupling points, are studied both in Markovian and non-Markovian regimes. The analytical solutions for nonreciprocal entanglement degree are given in the Markovian regime. It shows that the steady entanglement can be reached and strongly depends on the phases. Different from the case of the Markovian regime, the entanglement degree shows oscillating behavior in the non-Markovian regime. This work may find applications in the generation and controlling of entanglement in quantum networks based on waveguide quantum electrodynamics.