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Yu H.,Tongji University | Yu H.,Shanghai JiaoTong University | Yuan Y.,Tongji University | Yu G.,Shanghai Pudong Project Development Company Ltd | Liu X.,Tongji University
Tunnelling and Underground Space Technology | Year: 2014

The controlled blasting technique is employed, for the first time, on the diaphragm wall of an existing road tunnel in soft soils in the city of Shanghai, and therefore, safety demands on evaluation of influence of the blasting vibrations on the tunnel are highly required. Based on the practical blasting scheme of four sections of diaphragm wall of the tunnel to be exploded in three groups, the field monitoring of blasting vibrations is carried out on the bottom plate of the tunnel and the blasting vibration effects on the tunnel are measured throughout the blasting construction. The sequential characteristics of vibration velocities and accelerations of the tunnel structure are obtained from the field blasting tests. In order to fully understand the safety criterion of the blasting vibrations on the tunnel, a 3D numerical model is established by the finite element software ABAQUS. The numerical simulation results are confirmed by field monitoring data. Based on the monitoring data and numerical results of the tunnel subjected to blasting loads, results show: (1) the blasting energy is transferred mainly along the vertical direction; (2) the basic frequency domain of the tunnel responses caused by the explosion is relatively in a lower frequency ran≥ (3) distinct vibration response spectra of the tunnel structure are observed along the horizontal and vertical directions; (4) the performance of the tunnel subjected to the blasting construction is in a critical state of safety and thus the blasting construction scheme should be implemented carefully. Finally, critical issues on evaluation of the blasting construction are fully discussed and evaluated, which provide a reference for other similar projects. © 2014 Elsevier Ltd. Source

Zhang R.-Z.,Shanghai JiaoTong University | Liu C.-Y.,Shanghai JiaoTong University | Yin R.-H.,Shanghai JiaoTong University | Duan J.,Shanghai Pudong Project Development Company Ltd | Luo Y.-H.,Shanghai JiaoTong University
Fuel Processing Technology | Year: 2011

The present work studies the combustion of biomass syngas to characterize the NO-reduction by tar, benzene being selected as the representative model tar component. Experiments were carried out in a tubular flow reactor at atmospheric pressure and at different operating conditions i.e. an equivalence ratio of 0.5 to 2.5, temperatures between 1173 K and 1673 K and a reaction residence time of 50 to 100 ms. Kinetic parameters were determined from the experimental results. A simplified scheme of NO-reduction by benzene was presented and the effects of operating variables were concluded. The NO conversion is favored by an oxygen-rich condition, and the reduction efficiency falls with the rise of equivalence ratio, especially in the range of 0.5-1.0. Although high temperature enhances the reduction reactions, soot formation at high temperatures (1573 K, 1673 K) will seriously hinder the reduction of NO, which should be prevented. The ideal temperature is about 1473 K. 50 ms is found to be an insufficient residence time for the reduction. An increased contact time is of higher benefit at 1673 K where the heterogeneous reactions between NO and graphitized heavy hydrocarbons have a lower reaction rate. High pre-exponential factors and low activation energies are achieved under oxygen-rich conditions. © 2010 Elsevier B.V. All rights reserved. Source

Jiang F.,Shanghai Pudong Project Development Company Ltd
Tumu Gongcheng Xuebao/China Civil Engineering Journal | Year: 2011

Heat can be transferred quickly and effectively through the convection associated with fluid flow. The heat convection coefficients of asphalt pavement with different porosities and surface temperatures are calculated using the characteristic size and the equivalent particle diameter of porous asphalt. A thermal model is built with the finite element software ANSYS to analyze the temperature reduction performance of porous asphalt pavement with heat convection considered. It can be seen from the results that the temperature reduction performance of road surface is positively linearly correlated with the asphalt porosity. In the hot season, the temperature reduction performance of porous asphalt pavement is better than that of dense asphalt pavement. Comparing with long-term indoor and outdoor measured data, reliability analysis using the statistical software SPSS reveals a similarity coefficient of 0.98 for the calculation results. Source

Zhang R.-Z.,Shanghai JiaoTong University | Duan J.,Shanghai Pudong Project Development Company Ltd | Liu C.-Y.,Shanghai JiaoTong University | Luo Y.-H.,Shanghai JiaoTong University
Ranshao Kexue Yu Jishu/Journal of Combustion Science and Technology | Year: 2010

An experimental study on the effect of biomass gasification tar on NO reduction by biogas reburning has been performed in a ceramic flow reactor heated by an electric furnace. The biogas was composed of H2, CH4, CO, CO2 and N2, and the four tar model compounds were benzene, toluene, phenol and styrene. The reactor temperature was between 900°C and 1400°C. The influence of inlet content of tar, oxygen concentration, NO concentration, residence time and reactor temperature were studied to analyse the characteristics of biomass gasification-reburning. The results indicate that tar is helpful to increase NO reduction efficiency. Local equivalence ratio is an important parameter for NO reduction, and high NO reduction efficiency can be realized when bulk equivalence ratio varies between 1.20 and 1.65. NO reduction efficiency increases gradually with the rise of NO concentration and residence time. Soot forms at high temperature and high tar content. Source

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