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Deng A.,Hohai University | Yu Y.-T.,China Jikan Geotechnical Institute | Wang H.-B.,Nanjing Forestry University
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering

The thermal conductivity is a critical parameter of infrastructure materials, which are used as frost-resistant fills in cold regions. The parameter is mainly determined by the material composition. A frost-resistant fill, composed of waste foundry sand (WFS), fly ash (FA), expandable polystyrene (EPS), Portland cement and water, is proposed. ISOMET apparatus is used to measure the thermal conductivity of the fills, in particular, the effect of mixing ratios on the thermal conductivity of WFS-FA-EPS fills. The test results show that the increase of EPS beads, FA or cement results in the decrease of thermal conductivity of the fills. The increase in dry density or moisture contents enhances the thermal conductivity. The components in descending order affecting the thermal conductivity are EPS, FA and water. The increase of water-EPS/FA mass ratio increases the thermal conductivity of materials. The thermal conductivity of investigated specimens ranges between 0.5~1.0 W/m K, favorably less than that of general geomaterials, e.g., 1.0~2.0 W/m K. Source

Tang H.,China Jikan Geotechnical Institute | Liu D.-J.,Hefei University of Technology
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering

A dynamic model of vibration-sourced prompting and its corresponding governing equation are quoted. By solving the equations by four-step Runge-Kutta. With the general parameters of the vibration sources and pile, a figure of the pulse of exciting force is obtained. Then the figure is compared with another two different figures corresponding to two functions of pulse simulation .As a result, the accuracy and applicability of the functions is estimated. The effect of the mass of the vibration source, impact speed and the softness or hardness degree of the material on the strength and width of exciting force is simulated by changing a single parameter. Finally, it is demonstrated that the results from this solution are in accordance with the field test. Meanwhile the advantages and disadvantages of the model are also analyzed. Source

Gao G.Y.,Tongji University | Li N.,Tongji University | Zheng J.G.,China Jikan Geotechnical Institute
Applied Mechanics and Materials

In this paper, an exploration was presented to access the actual screening effectiveness of concrete wave impeding block (WIB) and the influence of WIB embedded depth on the vertical vibration isolation effect under the continuous vertical loading. Furthermore, the displacements of measuring points were simulated with a semi-analytical boundary element method (BEM) and validated by the measured records. It was found that a concrete WIB with a reasonable embedded depth was able to decrease the ground vibration greatly. It was also proved that decreasing the embedded depth was an efficient measure for WIB to reduce the dynamic response of ground. Besides, the good qualitative agreement between the calculation and the experiment proved the reliability of the numerical method. © (2010) Trans Tech Publications, Switzerland. Source

Ma M.,Beijing Jiaotong University | Liu W.,Beijing Jiaotong University | Qian C.,China Jikan Geotechnical Institute | Deng G.,Xian Metro Ltd. Company | Li Y.,Xian Metro Ltd. Company
Soil Dynamics and Earthquake Engineering

There is concern regarding the long-term vibration effects caused by metro trains on historic buildings. In this paper, the impact of metro train-induced vibrations on the Bell Tower in Xi'an above two spatially overlapping tunnels was studied. Metro Line 2 has been operational since 2011, and Line 6 is still under construction. To study and control the effect of micro vibrations on the Bell Tower, a metro train-track-tunnel-soil 3D dynamic FE model was developed. The vibration response generated by Line 2 was then predicted, and the influences of train speed on ground vibration were analysed. In addition, a detailed in situ measurement, which helped calibrate the numerical model and determine the dynamic behaviour of timber structures, was performed. Finally, the calibrated models and measured results were used to predict vibrations caused by road traffic and trains from two spatially overlapping metro lines. This was performed under different route schemes and train operation conditions. The results showed that installing steel spring floating slab tracks (FST) and decreasing train speeds had obvious effects on controlling the ground peak particle velocity (PPV). Simulated results from both the input impulse and output response generated by metro Line 2 matched well with actual measurements. If correct designs are employed, it is possible to resolve the vibration problem on historic buildings caused by metro trains. © 2015 Elsevier Ltd. Source

Deng J.,Xian University of Technology | Deng J.,China Jikan Geotechnical Institute | Wang J.,Xian University of Technology | Men Y.,Changan University
Xi'an Jianzhu Keji Daxue Xuebao/Journal of Xi'an University of Architecture and Technology

This paper discussed the stress characteristics and rules about anchor lattice beam based on the scientific indoor model test. This test has load on the tailing edge of the slope, get the press and strain distribution of the bottom soil of the lattice beam by the pressure cell and strain gauge put on the lattice beam. The result shows that with the increase of load pressure, the press and strain on the lattice beam increases, but the press on the cantilever end and mid-span of the lattice beam became diminished and the strain increased. On the other hand, the press on the cross of the lattice beam became greater and the strain became diminished. Overall the press and strain distribution on the lattice beam oresent to be of a triangle type. Source

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