Numerical analysis of loess and weak intercalated layer failure behavior under direct shearing and cyclic loading

The mechanical behavior of the joints inside a loess layer is greatly important in weak intercalation studies owing to its involvement in a wide range of landslides in the loess region in China.The shear behavior of the joints in the loess stratum during direct shear and cyclic loadings was investigated using the PFC2D discrete element software.Loess mudstone and mudstone with weak intercalated layer materials were subjected to direct testing,and cyclic shear tests were conducted with consideration to the influence of normal stress and shear velocity.The macroscopic properties and damage patterns were obtained for six numerical configurations;namely,loess-weathered mudstone with 0°,10°,and-10°joints and weathered mudstone with 0°,10°,and-10°weak intercalated layers.The numerical test results revealed that,in the direct shear tests,the shear stress and shear displacement of the samples increased with the normal stress.In the cyclic shear tests with a total cycle number N=20,the shear stress-shear strain curve of the six different configurations exhibited a hysteresis loop.The numerical tests also revealed that,under cyclic shear,the normal stress and shear velocity affected the shear strength.The degree of damage increased as the shear velocity decreased from 0.1 mm/s to 0.005 mm/s for all six numerical configurations.Compared with the damage pattern of the direct shear tests,the damage of the cyclic shear tests mainly comprised shear cracks and fractures,some shaking consolidation settlement and fewer shear strain occurred around the joints.In the direct shear tests,more compression cracks and fractures occurred in the samples.The damage mainly developed along the joints,and shearing-off damage occurred.The results obtained by this study further elucidate the failure mechanism and microscopic damage response of the joints in the loess stratum in Northwest China.

Intercalation Assembly and Chemical Product Engineering of Layered Intercalated Functional Materials Based on Efficient Utilization of Magnesium Resources in Salt Lakes

1 Introduction Magnesium salts are very important by-product of salt lake industry in West China.Nearly 200 million cubic meters of waste brine are released to the environment

Fabrication of intercalated p-aminobenzoic acid into Zn-Ti layered double hydroxide and its application as UV absorbent

An organic ultraviolet （UV） ray absorbent, p-aminobenzoic acid （PABA） was intercalated into a Zn-Ti layered double hydroxide （LDH） precursor by an anion-exchange reaction to obtain ZnTi-PABA-LDH, a new organic-inorganic nanocomposite. The structure and the thermal stability of ZnTi-PABA-LDH were characterized by XRD, FT-IR and TG-DTA. The results indicate ZnTi-PABA-LDH, synthesized by this method, exhibit relatively high crystallinity, and markedly enhanced thermal stability of PABA after intercalation into ZnTi-LDH. The UV-vis-NIR spectrophotometric and ESR data show excellent UV ray resistance and greatly decreased photocatalytic activity when PABA is intercalated into the interlayers of the ZnTi-LDH. The studies suggest that ZnTi-PABA-LDH may have potential applications as safe sunscreen materials.

Novel hybrids of Cu^(2+) ternary complexes of salicylidene-amino acid Schiff base with phenanthroline(or bipyridine) intercalated in Mg/Al-NO_3-layered double hydroxide

Four Cu2＋ complexes of salicylidene-amino acid Schiff base with 1,10-phenanthroline （Phen） or 2,2＇- bipyridine （Bipy） were successfully intercalated in interlayer galleries of Mg/AI-NO3-1ayered double hydroxide （LDH） by the swelling-restored method. The hybrids were characterized by elemental analysis, X-ray diffraction, FT-IR spectra, UV-vis DRS, TG-DTA and SEM observation. Good protection of the complexes by LDH in neutral and weak acidic solutions was revealed by UV spectra, cyclic voltammograms and luminescence spectra.

Facile synthesis and characterization of acetate intercalated Co-La layered double hydroxide

Layered double hydroxide（LDH） comprising of Co^2＋ and La^3＋-ions with acetate counter anion was successfully synthesized by hydrogen peroxide catalyzed hydrolysis reaction and characterized extensively. The observed reflections in the powder X-ray diffraction pattern could be indexed in P3 space group with a=0.316 nm and c=2.97 nm. Lattice fringes of distances corresponding to the peaks observed in X-ray diffraction pattern were observed in high resolution transmission electron microscopic images. UV-visible diffuse reflectance spectroscopy results confirmed the presence of Co（OH）6 along with the presence of charge-transfer band due to the interlayer carboxylate anion. Magnetization measurements at room temperature indicated high spin configuration of Co^2＋-ion in the sample exhibiting paramagnetic behavior. The mixed metal oxide from calcination was used to reconstruct the parent layered structure. Intercalation experiments with other organic anions in Co-La LDH proved be successful.

Comments on “Efficient adsorption of Mn(Ⅱ) by layered double hydroxides intercalated with diethylenetriaminepentaacetic acid and the mechanistic study.J.Environ.Sci.85,56-65”

In the paper entitled"Efficient adsorption of Mn(Ⅱ)by layered double hydroxides intercalated with di ethylenetriaminepentaacetic acid and the mechanistic study"in Journal of Environmental Sciences,volume 85,page 56-65,there were problems with mathematical notation and dimensional errors in the calculation for Giibbs free energy.In Section 2.5:Adsorption isotherms and thermodynamics studies,authors calculated the Gibbs free energy change(△G°)