Influence of Scale Effect on Strength and Deformation Characteristics of Rockfill Materials.

The hybrid method was adopted to model the original gradation of rockfill materials. According to the specification requirements, three simulated gradations of rockfill materials have been obtained. By the same token, the corresponding maximum particle sizes are 20 mm, 40 mm and 60 mm, respectively. With samples prepared under the same criterion of relative density, the scale effect on strength and deformation characteristics of the rockfill materials were studied by large-scale and consolidated-drained triaxial compression tests. The results show that when the confining pressure is higher, the peak deviator stress decreases with the increase of the maximum particle size. With the increase of the maximum particle size, the cohesion of rockfill materials gradually increases and the internal friction angle gradually decreases. Under the condition of the same maximum particle size, with the increase of confining pressure, the volume strain at the phase transition increases gradually, while the stress ratio at the phase transition decreases. Under the same confining pressure, the larger the particle size is, the smaller the volume strain becomes and the lower the stress ratio at the phase transition is. Therefore, the research results can provide a theoretical basis for establishing the constitutive model of rockfill materials considering the scale effect.

Preparation and Photocatalysis of CuO/Bentonite Based on Adsorption and Photocatalytic Activity.

A CuO/bentonite composite photocatalyst was prepared to fully utilize the adsorption capacity of bentonite and the photocatalytic activity of CuO. CuO and bentonite were chosen as a photocatalyst due to the excellent optical property of CuO and large specific surface area of bentonite, together with their high stability and low production cost. The sample was characterized by XRD, SEM, and BET. The effects of several factors on degradation process were investigated such as dosage of H2O2, irradiation time, pH of the solution, and dosage of catalyst. The optimum conditions for decolorization of methylene blue solution by CuO/bentonite were determined. Under optimal conditions, the decolorization efficiency of methylene blue by a 1.4% CuO/bentonite (400 °C) composite photocatalyst under visible irradiation at 240 min reached 96.98%. The degradation process follow edpseudo-second-order kinetics. The photocatalytic mechanism is discussed in detail. This composite structure provides a new solution to the cycle and aggregation of the photocatalyst in water.