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The internal inhomogeneous deformation and re-breaking characteristics of broken rock and coal during compaction are the basis for understanding porous structure evolution of the caved zone and then affect the enrichment of coalbed methane (CBM) in mining gob. In this paper, compression-AE experiments on limestone are carried out using a self-developed AE testing system. An AE location method, which is especially suitable for broken porous media is proposed. The results show that 1) the compression process of broken limestone can be divided into three stages: initial compression, linear compression, and plastic compression. There is a good correspondence between AE counts, energy and compression stages. 2) Broken limestone has layered re-breaking characteristics: the particle re-breaking firstly occurs in the middle layer and gradually moves toward the upper and lower layers as compression degree increases. The ultimate re-breaking degree in upper and middle layers is larger than that in lower layer. 3) The final screened results when strain rate reaches 0.24 show that the reduction of porosity is larger in upper and middle layers than that in lower layer under loading. The lower layer owns the largest porosity due to relative smaller compression degree.

This study focuses on the stability of stone column-supported and geosynthetic-reinforced embankments on soft soil. An upper-bound limit state plasticity failure discretization scheme (known as discontinuity layout optimization (DLO)), which determines the embankment stability without pre-assuming a slip surface, is used. The relationships between the stability of stone column-supported and geosynthetic-reinforced embankments and various influencing parameters, including the soil strength, geometric configuration, reinforcement strength, and area replacement ratio, are analysed. It is found that geosynthetics provide a significant contribution to embankment stability. Two failure mechanisms of geosynthetics (i.e., rupture failure and bond failure) are revealed and the effect of geosynthetics on embankment stability is governed by the failure mode. The application of stone columns mitigates the risk of geosynthetic failure. To provide an analytical solution for primary design in engineering practice, an approach based on the limit equilibrium method is proposed. Validations are performed with the DLO solution to demonstrate the accuracy and reliability of the developed analytical approach.

In this paper, the bearing capacity and the failure mechanism of obliquely loaded footings on sand overlying clay are determined by using discontinuity layout optimization (DLO) procedure. The solution is illustrated as a set of design charts with the use of dimensionless parameters. Parametric studies are performed to show that soil properties, geometric parameters, and load inclinations are all related to the bearing capacity and failure pattern. A simplified model is developed based on artificial data generated through DLO. Validations are carried out to demonstrate the accuracy of the developed model.

Soil deposits inevitably affect the seismic performance of underground structures, and underground tunnels are commonly constructed on sites composed of layered soil deposits. In this study, dynamic centrifuge tests and numerical modelling are conducted to enhance the fundamental understanding of the kinematic soil-tunnel interaction for tunnels constructed in layered soils that consist of muddy clay and silty clay. The site seismic response and tunnel seismic performance between the centrifuge and numerical modelling are compared. The acceleration time histories, amplification factors of the input motions, and the Fourier spectra between free field and structural field are experimentally and numerically investigated. For comparative purposes, parametric studies of tunnels in a single muddy clay and a single silty clay using verified numerical modelling are carried out. In addition, the dynamic bending moment and axial forces obtained by centrifuge and numerical modelling are compared with the solutions predicted by analytical methods in prior studies.

We epitaxially grew the metamagnetic FeRh films on ferroelectric PMN-PT(001) substrates and investigated the electric control of magnetic properties. An MgO buffer layer is inserted to reduce the considerably large lattice mismatch of 5.44% between FeRh and PMN-PT, leading to a nice epitaxial growth with a relationship of FeRh[110](001)||MgO[100](001)||PMN-PT[100](001). The as-grown FeRh film shows a typical antiferromagnetic-to-ferromagnetic phase transition by means of varying the temperature. Because a growth-induced uniaxial magnetic anisotropy is superimposed on the in-plane four-fold magnetocrystalline anisotropy, the epitaxial FeRh film displays different kinds of multi-step hysteresis loops at various field orientations. An electric field applied on the PMN-PT substrate can remarkably increase the coercivity of FeRh film, which presents a butterfly type shape, indicating a strain-mediated magnetoelectric coupling. Because of the inhibitory effect of the remnant compressive strain on the phase transition, the critical transition temperature and the magnetization are obviously enhanced and reduced, respectively, after removing the electric effect.

Conventional methods toward addressing the bearing capacity of strip footings on sand overlying clay may yield unreliable solutions. In this technical note, the bearing capacity of footings on sand overlying clay is evaluated using discontinuity layout optimization (DLO). A set of design charts that can be directly applied to the classical bearing capacity formulation is developed. Subsequently, a simplified regression-based approach, relevant to a wide range of geometric and strength parameters, is proposed. The model uncertainty for the proposed method is characterized. Validations are performed with the results of centrifuge tests and previously proposed analytical solutions.