Influence of air intake from existing shafts on the safety of operating trains.

Given the influence of air intake from inclined shafts in existing tunnel ventilation systems on train comfort and aerodynamic safety, a numerical analysis method is used to study the comfort and aerodynamic safety of operating trains under three conditions-inclined shaft closed and inclined shaft open without and with air intake-and to explore the variation law of transient pressure and aerodynamic force (lift coefficient, transverse force coefficient, and overturning moment coefficient). Combined with practical engineering and requirements, the influence of inclined shaft air intake on train operation comfort and aerodynamic safety is analyzed. Through this research, the influence of using air intake from the inclined shaft of an existing tunnel, a ventilation scheme of the new Wushaoling Tunnel, on the comfort and aerodynamic force of trains is revealed, and the comfort and aerodynamic safety of trains in an actual project are evaluated, verifying the rationality of the ventilation scheme of the Wushaoling Tunnel.

Embankment seismic fragility assessment: A case study on Xi'an-Baoji expressway (China).

Although embankment seismic damages are very complex, there has been little seismic fragility research yet. Researches on seismic fragility of bridges, dams and reinforced concrete (RC) structures have achieved fruitful results, which can provide references for embankment seismic fragility assessment. Meanwhile, the influencing degrees of retaining structures, such as retaining walls on the embankment seismic performances are still unclear. The K1025+470 embankment of the Xi'an-Baoji expressway was selected as the research object, and the finite difference models of the embankment fill-soil foundation system and embankment fill-soil foundation-retaining wall system were established. The ground-motion records for Incremental Dynamic Analysis (IDA) were selected and the dynamic response analysis were conducted. Probabilistic Seismic Demand Analysis (PSDA) was used to deal with the IDA results and the seismic fragility curves were generated. Based on the assessment results, the influences of the retaining wall on the embankment seismic fragility were further verified. The research results show that regardless of which seismic damage parameter is considered or the presence or absence of the retaining wall, larger PGAs always correspond to higher probabilities of each seismic damage grade. Seismic damages to the embankment fill-soil foundation-retaining wall system are always lower than those of the embankment fill-soil foundation system under the same PGA actions, thus, the retaining wall can decrease the embankment seismic fragility significantly.

Susceptibility mapping and zoning of highway landslide disasters in China.

Prominent regional differentiations of highway landslide disasters (HLDs) bring great difficulties in highway planning, designing and disaster mitigation, therefore, a comprehensive understanding of HLDs from the spatial perspective is a basis for reducing damages. Statistical prediction methods and machine learning methods have some defects in landslide susceptibility mapping (LSM), meanwhile, hybrid methods have been developed by combining the statistical prediction methods with machine learning methods in recent years, and some of them were reported to perform better than conventional methods. In view of this, the principal component analysis (PCA) method was used to extract the susceptibility evaluation indexes of HLDs; the particle swarm optimization-support vector machine (PSO-SVM) model and genetic algorithm-support vector machine (GA-SVM) model were implemented to the susceptibility mapping and zoning of HLDs in China. The research results show that the accumulative contribution rate of the four principal components is 92.050%; evaluation results of the PSO-SVM model are better than those of the GA-SVM model; micro dangerous areas, moderate dangerous areas, severe dangerous areas and extreme dangerous areas account for 24.24%, 19.49%, 36.53% and 19.74% of the total areas of China; among the 1543 disaster points in the HLDs inventory, there are 134, 182, 421 and 806 located in the above areas respectively.

Dynamic effect of metro-induced vibration on the rammed earth base of the Bell Tower.

Xi'an Bell Tower (the Bell Tower) is a state-level ancient relic in China. The vibration caused by metro will exert adverse effect on the Bell Tower. This paper aims at presenting 3D-FEM models to predict the peak period velocity (PPV) of rammed earth base when the metro passing through the Bell Tower. The calculation results are compared with those of field test. Both results were found to be in good agreement. Furthermore, the results indicated that the effect of shock absorption measures is significant. The shock absorption tracks can obviously decrease the vibration of the Bell Tower, and the maximum decrease of PPV of the rammed earth base is 78.91 %. The proposed prediction has the potential to be developed as a decision and management tool for the evaluation of the risk associated with the influence of vibration caused by metro on buildings in urban areas.

3-Chloro-pyridin-2-amine.

In the title compound, C(5)H(5)ClN(2), a by-product in the synthesis of ethyl 2-(3-chloro-pyridin-2-yl)-5-oxopyrazolidine-3-carboxyl-ate, the amine groups form inter-molecular hydrogen-bonding associations with pyridine N-atom acceptors, giving centrosymmetric cyclic dimers. Short inter-molecular Cl⋯Cl inter-actions [3.278 (3) Å] also occur.