Experimental study on seismic reinforcement of bridge foundation on silty clay landslide with inclined interlayer

A shaking table test for a bridge foundation reinforced by anti-slide piles on a silty clay landslide model with an inclined interlayer was performed.The deformation characteristics of the bridge foundation piles and anti-slide piles were analyzed in different loading conditions.The dynamic response law of a silty clay landslide with an inclined interlayer was summarized.The spacing between the rear anti-slide piles and bridge foundation should be reasonably controlled according to the seismic fortification requirements,to avoid the two peaks in the forced deformation of the bridge foundation piles.The“blocking effect”of the bridge foundation piles reduced the deformation of the forward anti-slide piles.The stress-strain response of silty clay was intensified as the vibration wave field appeared on the slope.Since the vibration intensified,the thrust distribution of the landslide underwent a process of shifting from triangle to inverted trapezoid,the difference in the acceleration response between the bearing platform and silty clay landslide tended to decrease,and the spectrum amplitude near the natural vibration frequency increased.The rear anti-slide piles were able to slow down the shear deformation of the soil in front of the piles and avoid excessive acceleration response of the bridge foundation piles.

Clay mineral expansion of black cotton soil based on interlayer cation hydration

To analyze the water swelling characteristics of black cotton soil(BCS),X-ray fluorescence and X-ray diffraction characterizations were performed to investigate the chemical compositions and types of clay minerals in BCS.A montmorillonite crystal lattice was established to simulate the hydration of interlayer cations by applying the SPC/E potential energy model,universal force field,algorithm of charge balance,and periodic boundary.Results indicated that the main clay mineral found in the BCS was montmorillonite(32.6%)with small amounts of interstratified illite-montmorillonite(10.9%),illite(2.3%),and kaolinite(1.5%).The high expansive potential of BCS comes from the strong adsorption property of montmorillonite with a high content of magnesium and sodium ions to water molecules.The exchangeable cations of Na^(+)in BCS were only 3.73%,but they enhanced the adsorption capacity of clay to water molecules and accelerated the hydration of Mg^(2+)(47.1%)and Ca^(2+)(4.78%).The free swell index can be used as a classification index of the swelling potential of BCS.

Interlayer Prediction Method for Braid River Reservoirs in Offshore Oil Field

The interlayer structure of braid river reservoirs is complex and the interwell prediction is difficult in offshore oil field. Taking CFD11-1 oilfield of NgⅢ sand as an example, based on layer contrasting, the interlayer is divided into muddy interlayer, clay boulder interlayer, and physical interlayer according to lithology. Under the guidance of sedimentary model, we use the geology statistical inversion method to predict the clay boulder interlayer, consistent with the dynamic characteristics of oil production which is used for the prior quality control. The results of this study can objectively reveal the characteristics of interlayer space distribution. Compared with the traditional multi-well comparison and stochastic simulation model, this method is applied to the offshore oil field which is character with wide well space, sparse well network, which has very high application value in predicting the interlayer and deploying of inter-well encryption in the similar oilfield.

Methane Adsorption on Montmorillonite, Kaolinite and Illite at High Pressures

Shale gas, which is derived from organic matters in shale and stored in shale deposits, is an important unconventional gas resource and attracts attention due to its significant requirement in the hydrocarbon production. Methane (CH4) is the dominant component of shale gas, and adsorbed gas is an important reservoir form. Many studies have investigated the adsorption capacities and adsorption mechanisms of CH4 in shale. Organic matters and clay minerals have been proposed to be the two major components for CH4 adsorption. Adsorption of CH4 in organic matters, such as the adsorption capacity and effects of characteristics of the organic matters, has been well investigated. However, studies on CH4 adsorption on clay minerals have mainly focused on evaluating the adsorption capacity, and very little information about the adsorption mechanism has been provided. For example, the adsorption sites and factors influencing CH4 adsorption on clay minerals remain unclear. Three main reasons account for this: (1) the co-existence of organic matters in samples affects the evaluation of CH4 adsorption on clay minerals; (2) the pressures used during adsorption are not representative of actual reservoir pressures; and (3) the clay minerals selected have low swelling capacity and a smaller interlayer distances than a CH4 size, resulting in the misunderstanding of the CH4 adsorption sites.

Application of aluminosilicate clay mineral-based composites in photocatalysis

Aluminosilicate clay mineral(ACM)is a kind of typical raw materials that used widely in manufacturing industry owing to the abundant reserve and low-cost exploring.In past two decades,in-depth understanding on unique layered structure and abundant surface proper-ties endows ACM in the emerging research and application fields.In field of solar-chemical energy conversion,ACM has been widely used to support various semiconductor photocata-lysts,forming the composites and achieving efficient conversion of reactants under sunlight irradiation.To date,classic ACM such as kaolinite and montmorillonite,loaded with semi-conductor photocatalysts has been widely applied in photocatalysis.This review summaries the recent works on ACM-based composites in photocatalysis.Focusing on the properties of surface and layered structure,we elucidate the different features in the composition with various functional photocatalysts on two typical kinds of ACM,i.e.,type 1∶1 and type 2∶1.Not only large surface area and active surface hydroxyl group assist the substrate adsorption,but also the layered structure provides more space to enlarge the application of ACM-based photocatalysts.Besides,we overview the modifications on ACM from both external surface and the inter-layer space that make the formation of composites more efficiently and boost the photo-chemical process.This review could inspire more upcoming design and synthesis for ACM-based photocatalysts,leading this kind of economic and eco-friendly materials for more practical application in the future.

Quantitative characterization of reservoir space in the Lower Silurian Longmaxi Shale,southern Sichuan,China

Based on the drilling data of the Upper Ordovician Wufeng Shale and the Lower Silurian Longmaxi Shale in southern Sichuan Basin,the construction of matrix pores and the development condition of fractures in a marine organic-rich shale are quantitatively evaluated through the establishment of the reservoir petrophysical models and porosity mathematical models.Our studies show that there are four major characteristics of the Longmaxi Shale confirmed by the quantitative characterization:(1)the pore volume of per unit mass is the highest in organic matter,followed in clay minerals,finally in brittle minerals;(2)the porosity of the effective shale reservoir is moderate and equal to that of the Barnett Shale,and the main parts of the shale reservoir spaces are interlayer pores of clay minerals and organic pores;(3)the porosity of the organic-rich shale is closely related to TOC and brittle mineral/clay mineral ratio,and mainly increases with TOC and clay mineral content;(4)fractures are developed in this black shale,and are mainly micro ones and medium-large ones.In the Longmaxi Shale,the fracture density increases from top to bottom,reflecting the characteristics with high brittle mineral content,high Young’s modulus,low Poisson's ratio and high brittleness at its bottom.

Preparation and Characterization of Exfoliated Poly（ethyleneterephthalate）/Montmorillonite Nanocomposites Using Modified MMTs with Variable Content of Antimony Acetate

Poly（ethylene terephthalate） （PET）/montmorillonite （MMT） nanocomposite was prepared by the direct polymerization with MMTs modified with variable content of antimony acetate （Sb（OAc）3）, which was also used as catalyst polymerization. The modified MMTs （AS-Sb-MMT） were prepared by intercalating both Sb（OAc）3 and amphoteric surfactant （AS） into MMT layers. Nine kinds of Sb-MMTs [MMT treated with Sb（OAc）3] with different Sb content were obtained, but only six kinds of PET/MMT nanocomposites could be prepared. ICPAES was used to characterize Sb content of modified MMT, XRD was used to characterize interlayer spacing, IR spectroscopy was used to characterize composition change of Sb catalyst in modified MMT and TEM was used to investigate micromorphology of PET/MMT nanocomposites. Several results are obtained, i.e., （a） Sb content of Sb-MMT is affected by both drying temperature and washing-drying sequence, （b） compared with Na-MMT （unmodified MMT）, the change in the interlayer spacing of Sb-MMT is attributed to the solvent ethylene glycol （EG） rather than the intercalated or absorbed Sb（OAc）3, （c） based on this, a model is developed to describe the swelling of Na-MMT and modified MMT by EG and the effect of drying temperature on the interlayer spacing, （d） exfoliation state of MMT in PET matrix of nanocomposites is controlled not only by Sb content and interlayer spacing, but also by the composition of Sb catalyst in modified MMT.