Micromechanics of rock damage: Advances in the quasi-brittle field

Constitutive models play an essential role in numerical modeling and simulation of nonlinear deformation, progressive damage and failure of rock-like materials and structures. Recent advances in the quasi-brittle field show that upscaling methods by homogenization have provided a new efficient way to derive macroscopic formulations of rocks from their microstructure information and local properties and then to model nonlinear mechanical behaviors identified at laboratory. This paper aims first at relating the mechanical phenomena on sample scale to their respective mechanisms on microscale. Main focus is put on unilateral effects due to crack’s opening/closure transition, material anisotropy induced by crack growth in some preferred directions and multiphysical coupling at microcracks. After a brief introduction to the linear homogenization method and its application to crack problems, we present some recent advances achieved in the combined homogenization/thermodynamics framework, including anisotropic unilateral damage-friction coupling, theoretical failure prediction in conjunction with deformation analyses, poromechanical coupling, analytical solutions and numerical implementation with application to typical brittle rocks.

Coca-Cola＇s Proposed Acquisition of Huiyuan： Revisiting the MOFCOM Decision

This paper revisits the Coca-Cola/Huiyuan case, using quantitative methods. We first estimate the demand system of carbonated soft drinks and juices, using the data of the 4-digit code Chinese soft drink industry. We then define the relevant market by implementing the SSNIP test （a.k.a. the hypothetical monopolist test）. Finally, we evaluate the unilateral effect on the juices market with merger simulation. Our results show that carbonated soft drinks and juicess are in two separate relevant markets. More importantly, there may, be a significant unilateral effect on the juices market based on scenario analysis. 7his result confirms the MOFCOM decision itself, but highlights that competition damage comes more from unilateral efect than from the dubious portfolio effect.

Safety evaluation of Dagangshan arch dam resisting strong earthquakes with a rate-dependency anisotropic damage model

This paper presents a model to simulate the safe behavior of Dagangshan arch dam with a rate-dependency anisotropic damage model. This model considers the damage of asymmetry and anisotropy under cyclic loading of tension and compression, and it is used in the compiled finite element code. The material parameters used in the model can be identified from uniaxial static and dynamic experiments. Thereafter, it is used for analyzing damage and failure patterns of the dam subjected to water pressure and strong earthquakes. The numerical results show that it is necessary to consider both asymmetry between tension and compression and anisotropy of damage. Severe damage regions of the dam reveal brittle and risky positions clearly. Meanwhile damage patterns show the failure trend and safety behaviors of the dam. These results match well with that of the experiments carried out in DUT. The proposed model may be used to predict the damage patterns and potential failure modes of concrete structures like the dam. And the aseismic performance of the dam can be figured out.