DISTRIBUTION OF ACTIVE EARTH PRESSURE OF RETAINING WALL WITH WALL MOVEMENT OF ROTATION ABOUT TOP

Based on the Coulomb's theory that the earth pressure against the back of a retaining wall is due to the thrust exerted by the sliding wedge of soil from the back of the wall to a plane which passes through the bottom edge of the wall and has an inclination equal to the angle of θ, the theoretical answers to the unit earth pressure, the resultant earth pressure and the point of application of the resultant earth pressure on a retaining wall were obtained for the wall movement mode of rotation about top. The comparisons were made among the formula presented here, the formula for the wall movement mode of translation, the Coulomb's formula and some experimental observations. It is demonstrated that the magnitudes of the resultant earth pressures for the wall movement mode of rotation about top is equal to that determined by the formula for the wall movement mode of translation and the Coulomb's theory. But the distribution of the earth pressure and the points of application of the resultant earth pressures have significant difference.

General variational solution for seismic and static active earth pressure on rigid walls considering soil tensile strength cut-off

According to the limit equilibrium state of soils behind rigid walls and the pseudo-static approach,a general closed-form solution to seismic and static active earth pressure on the walls,which considers shear and tension failure of the retained soil,is put forward using a variational calculus method.The application point of the active resultant force specified in the proposed method is explained with a clear physical meaning related to possible movement modes of the walls.In respect of the derived nine dependent equations reflecting the functional characteristics of the earth pressure,the proposed method can be performed easily via an implicit strategy.There are 13 basic factors related to the retained soils,walls,and external loads to be involved in the proposed method.The tension crack segment of the slip surface is obviously influenced by these parameters,apart from vertical seismic coefficient and geometric bounds of the surcharge,but the shear slip segment maintains an approximately planar shape almost uninfluenced by these parameters.Noticeably,the proposed method quantitatively reflects that the resultant of the active earth pressure is always within a limited range under different possible movements of the same wall.

Upper bound solution to seismic active earth pressure of submerged backfill subjected to partial drainage

In waterfront geotechnical engineering,seismic and drainage conditions must be considered in the design of retaining structures.This paper proposes a general analytical method to evaluate the seismic active earth pressure on a retaining wall with backfill subjected to partial steady seepage flow under seismic conditions.The method comprises the following steps:i)determination of the total head,ii)upper bound solution of seismic active earth thrust,and iii)deduction for the earth pressure distribution.The determination of total head h(x,z)relies on the Fourier series expansions,and the expressions of the seismic active earth thrust and pressure are derived by using the upper bound theorem.Parametric studies reveal that insufficient drainage and earthquakes are crucial factors that cause unfavorable earth pressure.The numerical results confirm the validity of the total head distribution.Comparisons indicate that the proposed method is consistent with other relevant existing methods in terms of predicting seismic active earth pressure.The method can be applied to the seismic design of waterfront retaining walls.

Earth Pressure of Retaining Structure Induced by Subgrade under Rainfall

This article selects the retaining wall as the research object, introducing the rainfall infiltration model, considering the infiltration of rainwater into the groundwater recharge, analysizing the variation of earth pressure in the subgrade retaining wall. On this occasion, the back of retaining wall produces stable seepage water and compares with the non drainage water body. The results show that, with the infiltration of rainwater into the groundwater recharge, the greater the active earth pressure under the condition of rainfall appears, more quickly the active earth pressure of the retaining wall with the drainage body increases. The matrix suction of unsaturated soils, which is infiltrated into soil of subgrade, has a positive effect on the shear strength of the earth pressure.

Research on K-V-rare Earth Metal Catalysts for Diesel Soot Oxidation

Five types of KNO_3-NH_4VO_3-rare earth metal nitrate（K-V-rare earth metal） catalysts supported on a-porous alumina ceramic substrates were prepared by a coating method. All the catalysts were characterized by X-ray diffraction and thermogravimetry/differential scanning calorimetry. Catalytic activities were evaluated by a soot oxidation reaction using a temperature-programmed reaction system. The experimental results show that the addition of rare earth metal compound could obviously improve the catalytic activities of the K-V-based catalysts. The proper ratio of K-V-rare earth metal catalysts can not only lower the soot onset ignition temperature, but also quicken the soot oxidation rate. The crystalline phases formed by K, V, and rare earth metal are stable.

Synthesis of CaO-SiO_2-B_2O_3∶Sm_2O_3 Glasses and Luminescent Properties of Sm^(3+)

CaO-SiO2-B2O3 ：Sm2O3 glasses were synthesized in air atmosphere with conventional high temperature process. The optimal temperature of synthesis, the absorption spectrum and the luminescent properties of the glasses were studied. The fluorescence spectrum of Sm^3＋ was observed in CaO-SiO2-B2O3 ： Sm2O3 glasses. The fluorescence spectrum of the sample has three major emission bands peaking at 568, 605 and 650 nm respectively. The strongest emission band peak at 605 nm. It is concluded that the emissions were caused by the f-f transition of the 4f electrons of Sm^3＋. The emission bands peaking at 568, 604 and 650 nm correspond to the ^4G5/2→^6H5/2 transition, ^4G5/2→^6H7/2 transition and ^4G5/2→^6H9/2 trasition respectively. The luminescent properties of CaO-SiO2-B2O3 glasses indicate that the glass can convert the ultraviolet in the sunlight into red light, thus increasing the intensity of red light. The luminescent properties of these glasses may be used to make kinds of light-conversion glass for agriculture.

Active manganese oxide on MnOx-CeO2 catalysts for low-temperature NO oxidation：Characterization and kinetics study

MnO_x-CeO_2 catalysts were synthesized to investigate the active sites for NO oxidation by varying the calcination temperature. XRD and TEM results showed that cubic CeO_2 and amorphous MnO_x existed in MnO_x-CeO_2 catalysts. High temperature calcination caused the sintering of amorphous MnO_x and transforming to bulk crystalline Mn_2O_3, H_2-TPR and XPS results suggested the valence of Mn in MnO_x-CeO_2 was higher than pure MnO_x, and decreased with the increasing calcination temperature, The turnover frequency（TOF） was calculated based on the initial reducibility according to H_2-TPR quantitation and kinetic study. The TOF results indicated that the initial reducibility of amorphous MnO_x with high valence manganese ions was equivalent to the active sites for NO oxidation. It can be inferred that the amorphous MnO_x plays a key role in low-temperature NO oxidation.

Watershed systems science—A new paradigm to understand and govern the impact of human activities on the earth's surface in the Anthropocene

Recent scholars’work in Vol 58 Issue 1(2015)and Cheng and Li’s paper in Vol 58 Issue 7(2015)in Science China Earth Sciences propose development of"Watershed science"by"Bridging new advances in hydrological science with good management of river basins".An analysis of the language and key concepts used in the abstracts,titles and keywords of this set of 8 papers and an editorial reveals that‘Watershed’,‘River’,‘Science’and‘System’are the

Synthesis, characterization, biological activities and luminescent properties of lanthanide complexes with [2-thiophenecarboxylic acid, 2-(2-pyridinylmethylene)hydrazide] Schiff bases ligand

A Schiff base L [2-thiophenecarboxylic acid, 2-（2-pyridinylmethylene）hydrazide] with its lanthanide metal complexes was synthesized. These complexes were characterized by elemental analysis, molar conductivity measurements, spectral analysis（NMR, FT-IR, and UV-Vis）, luminescence and thermal gravimetric analysis. The Schiff base ligand was a tridentate chelate and coordinates to the central lanthanide ion with 1：2 metal：ligand ratio. The conductivity data showed a 1：1 electrolytic nature with a general formula [LnL_2（NO_3）_2]NO_3. The luminescence emission properties for Sm, Tb, and Eu complexes were observed and showed that the ligand L could absorb and transfer energy to Sm（III）, Tb（III） and Eu（III） ions. The complexes possessed a good antibacterial activity against different bacterial strains. In addition, the scavenging activity of the Ln（III） complexes on DPPH was concentration dependant and the complexes were significantly more efficient in quenching DPPH than the free Schiff base ligand.

Electrochemical behavior of praseodymium and Pr-Al intermetallics in LiCl-KCl-AlCl_3-PrCl_3 melts

The electrochemical behavior of Pr（Ⅲ） and formation process of Pr-Al intermetallics were investigated by different electrochemical methods. The reduction of Pr（Ⅲ） ion to metallic Pr is an one-step three-electrons reaction. The reversibility of Pr（Ⅲ）/Pr（0） system was evaluated by cyclic voltammograms with different scan rates. The co-reduction of Pr（Ⅲ） and Al（Ⅲ） ions formed three different Pr-Al intermetallics at electrode potentials around-1.40,-1.80,and-1.95V vs.Ag/AgCl at 723 K,respectively.Open-circuit chronopotentiometry and electromotive force（emf） measurements were carried out to estimate the relative molar Gibbs energies of Pr for the formation of different Pr-Al intermetallics in the temperature range of 723–843K.The activities of Pr in the Pr-Al intermetallic compounds were calculated.

Cerium based shells with palladium cores encapsulated:an efficient catalyst for carbon monoxide oxidation

Pd@Zr/Ce O2 core-shell catalyst prepared by hydrothermal method was applied in CO oxidation reaction, exhibiting high CO oxidation activity at low temperature.XRD（X-ray diffraction） analysis demonstrated that the remarkable enhancement of catalytic performance was found to depend on the presence of more oxygen vacancies in the core-shell structure, which contributed higher content of and ready release of active oxygen species at low temperature, confirmed by H2-TPR（temperature programed reduction） results.Interestingly, introducing a small amount of zirconium（0.5 wt.%） exhibited a significant improvement of catalytic activity because the introduction of Zr further improved the amount of crystal defects and promoted the migration of oxygen species.