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With the widespread construction of railways, many mountainous single-line railway yards need to be expanded, and existing protection measures against rockfall are inadequate to protect stations and other infrastructure following expansion. Based on the actual engineering background, in this paper the movement trajectory of falling rocks on a high and steep slope is simulated using RocFall software, and the bouncing height, movement speed and impact energy of falling rocks are derived. According to the numerical simulation results, the rockfall protection measure of rockfall drapery systems plus the combination of rockfall embankments and rock sheds is proposed. The structure of a rockfall embankment–rock shed is a new type of combined protection measure, in which the rockfall embankments are built on top, with the existing rock shed or new portal foundation and top plate working as the lower foundation. This study shows that this new combination structure can resist the impact of falling rocks with a high factor of safety; the effective interception height of rockfall embankments is increased and the problem of rockfall crossing is solved with the construction of rockfall embankments on top of a rock shed or portal foundation. [ABSTRACT FROM AUTHOR]

Assessing the stability of embankments during railway operation is paramount for ensuring safety of railway. However, directly measuring the strength of fill materials can be challenging when the railway is in use. A strong correlation has been observed between soil shear strength and small strain stiffness. By establishing a robust correlation between shear strength and small-strain stiffness in the laboratory, considering various of factors, and combining it with field measurement of in-situ soil small stiffness might be an effective way to this problem. This study focuses on a type of filling materials commonly used in southwestern parts of China for railway construction: fully weathered red mudstone (FWRM) and its lime-treated counterpart (LFWRM), as the objects. A series of triaxial and unconfined compression tests were conducted to examine the effects of water content, confined pressure, and lime treatment on the shear strength and small strain stiffness of FWRM and LFWRM. The results show that the strength and stiffness of FWRM significantly decrease with increasing water content, while LFWRM specimens demonstrate good resistance. All LFWRM specimens displayed a brittle shear behavior. Empirical correlation was established for FWRM and LFWRM. The relationship for LFWRM is water content independent, meanwhile for FWRM is strongly dependent upon whether soil is saturated or not. The ratio of small strain stiffness to strength (E max /q max) for FWRM decreases substantially after saturation, whereas it remains almost constant for LFWRM. The reduction in strength and stiffness can be attributed to the degradation of the soil fabric due to increasing water content, where the pore size distribution (PSD) of FWRM changes significantly with increasing water content due to aggregate swelling. However, for LFWRM, the PSD remains bi-modal, which is due to the cementation bonding observed between lime-treated aggregates that explains the stable structure and improved performance of LFWRM. • Water content, confined pressure and lime treatment effect on the mechanical behaviour of fully weathered red mudstone. • Microstructural modification mechanism of lime treated fully weathered red mudstone. • Relationship between shear strength and small strain stiffness of fully weathered red mudstone. [ABSTRACT FROM AUTHOR]

Red mudstone is widely distributed in the southwest part of China, and it has been used as the fill material in the construction of railway embankment. Shakedown behavior of saturated red mudstone fill material(SRMF) was characterized via a series of drained cyclic triaxial tests. Three types of deformation response were recorded in this study. Strong correlation was observed between deformation response and stress state (confining pressure, cyclic amplitude and cyclic stress ratio). In order to determine the shakedown limit and the creep limit, responses of axial strain, axial strain rate and dissipated energy were used. Especially for the determination of the creep limit, correlation between dissipated energy and cyclic stress ratio was used to overcoming the difficulty encountered in conventional method. Tests results showed that the cyclic stress ratios corresponding to the shakedown and creep limits were lower than the monotonic compression strength. A clear power function was identified to correlate the limits with confining pressure. • Deformation responses of SRMF under normal and higher cyclic stress level were studied. • Shakedown and dissipated energy were used together to categorize the deformation modes. • Correlation between cyclic stress ratio limits and confining pressure was established. • Differences on cyclic modulus and strength between SRMF and conventional UGMs were identified. [ABSTRACT FROM AUTHOR]

The magnetic and electronic properties of the geometrically frustrated triangular antiferromagnet CuCrO2 are investigated by first principles through density functional theory calculations within the generalized gradient approximations (GGA)+U scheme. The spin exchange interactions up to the third nearest neighbours in the ab plane as well as the coupling between adjacent layers are calculated to examine the magnetism and spin frustration. It is found that CuCrO2 has a natural two-dimensional characteristic of the magnetic interaction. Using Monte-Carlo simulation, we obtain the Néel temperature to be 29.9 K, which accords well with the experimental value of 24 K. Based on noncollinear magnetic structure calculations, we verify that the incommensurate spiral-spin structure with (110) spiral plane is believable for the magnetic ground state, which is consistent with the experimental observations. Due to intra-layer geometric spin frustration, parallel helical-spin chains arise along the a, b, or a+b directions, each with a screw-rotation angle of about 120°. Our calculations of the density of states show that the spin frustration plays an important role in the change of d-p hybridization, while the spin-orbit coupling has a very limited influence on the electronic structure. [ABSTRACT FROM AUTHOR]

Abstract: Synthesis of 2,3-epoxyl-1,3-diaryl-1-propanone via epoxidation of chalcone with aqueous sodium hypochlorite was carried out in 62–92% yields using benzyldimethyltetradecyl ammonium chloride as phase transfer catalyst under ultrasound irradiation. Compared to the classical method, the advantages of this method are a safer oxidant, mild conditions, no toxic solvent and shorter reaction time. [Copyright &y& Elsevier]

This study systematically presents the application of machine learning (ML) algorithms for constructing a constitutive model for soils. A genetic algorithm is integrated with ML algorithms to determine the global optimum model, and the k-fold cross-validation method is used to enhance the models' robustness. Three typical ML algorithms with formulations explicitly expressed [i.e., back-propagation neural network (BPNN), extreme learning machine (ELM) and evolutionary polynomial regression (EPR)], and two modelling strategies (i.e. total or incremental stress–strain strategies) are used. A synthetic database is first generated based on a simple constitutive model to objectively evaluate the performance of three ML algorithms and two modelling strategies. Next, the optimum ML algorithm and the well evaluated modelling strategy are applied to experimental tests for examining its robustness. All results indicate that a BPNN-based constitutive model using the incremental stress–strain strategy performs best in modelling the mechanical behaviour of soils in terms of interpolation and extrapolation abilities, followed by ELM and then EPR. [ABSTRACT FROM AUTHOR]

Abstract: A mild and efficient method has been developed using ultrasound irradiation for oxidative cleavage of hydrobenzoin with ACC/silica gel in dichloromethane. A high yield of 72–99% has been obtained for the oxidation of a series of hydrobenzoins into aromatic aldehydes at room temperature. [Copyright &y& Elsevier]

MDPE- g-MAH copolymers were prepared with MDPE (medium density polyethylene) and MAH (maleic anhydride) under different irradiation doses of high-energy electron accelerator, and FTIR spectra confirmed their structure. The effect of the different contents of MDPE- g-MAH copolymers on properties of MDPE/CaCO system is studied intensively. By adding 4 Phr (parts per hundred of resin) MDPE- g-MAH in MDPE/CaCO system under irradiation dose of 0.7 MGy, the tensile strength increases from 16.3 MPa to 19.9 MPa, and elongation at break increases from 437% to 518%. SEM images show the domain size of CaCO in MDPE- g-MAH systems becomes small. Definitely, MDPE- g-MAH copolymer could improve the compatibility of MDPE/CaCO system effectively. [ABSTRACT FROM AUTHOR]