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Wang Z.-H.,Guangzhou Metro Design and Research Institute Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering

The covering top-down method can be better applied to large urban underground construction in city downtown areas, which is inverse in construction under the covering conditions. The design scheme for deep excavation of Pingleyuan Station of Beijing Metro line No. 14 is introduced. The stress characteristics, selection principles, design points of horizontal and vertical systems of the excavation are discussed. Some key problems are also analyzed. It may provide reference for similar projects. Source

Li L.P.,South China University of Technology | Wang L.,Guangzhou Metro Design and Research Institute Co.
Applied Mechanics and Materials

The tests about elastic properties of a commercial vehicle cab suspension air spring were carried out. And the experimental results show that: the higher the initial pressure of the air bag, the greater its carrying capacity, and the bigger the damping; at the same excitation frequency and the vibration amplitude, the dynamic stiffness of the air spring is gradually increased as the initial pressure is increased; in the low frequency range, at the same vibration amplitude and inside pressure, the dynamic stiffness of the air spring is increased as the increasing of the excitation frequency. © (2014) Trans Tech Publications, Switzerland. Source

Wang R.,Southwest Jiaotong University | Qi T.,Southwest Jiaotong University | Lei B.,Southwest Jiaotong University | Li Y.,Guangzhou Metro Design and Research Institute Co. | Zhu X.,Southwest Jiaotong University
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering

The segmentation and characteristic extraction of lining crack image are essential for the automatic crack detection. The digital image processing analysis was optimized and some algorithms were improved based on the large number of collected images from tests. For the image segmentation, a new algorithm of binarization combining Prewitt operator with Otsu threshold was proposed. The binary image processed by the new algorithm, combined with the mathematical morphology resulted in the one with more complete fracture zones and less interference regions. For characteristic extraction, area, perimeter, compactness, rectangle degree, Feret's occupying rate and the mean width were defined as the morphological characteristics. The results of application showed that the integrated algorithm achieved the better image segmentation and was more suitable for the crack image with complex background. The characteristics extracted from the different regions in the image formed a representative information base and laid a foundation for automatic identification of cracks. ©, 2015, Academia Sinica. All right reserved. Source

Zhang Y.-M.,Guangzhou Metro Design and Research Institute Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering

According to different surrounding building conditions, the forming process of diaphragm wall trench construction in water-rich sand stratum is analyzed by means of the method of finite element numerical simulation. In the process, the module of simulating mud is used. According to the calculated results, the mutual influence of different buildings and diaphragm wall trench construction is investigated. The effects of reinforcement measures are also analyzed, and the relevant rules are obtained. Source

Liu X.,Hohai University | Liu X.,Guangzhou Metro Design and Research Institute Co. | Lei G.,Hohai University | Zhang K.,Hohai University
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology)

Three symmetrically stacked tubes, placed on a rigid horizontal foundation and filled with either water or slurry, were analyzed. Two stacked forms, with two underlying tubes in mutual contact and in isolation, were considered. The frictions at the tube-tube and the tube-foundation interfaces were also considered. Analytical solutions were derived for the tension, friction and shape of tubes. Investigations were carried out on the mechanical responses of tubes to the internal filling pressure and the stacked distance between two underlying tubes. Moreover, the stability of stacked tubes was addressed. The results show that for a specified stacked distance, there is a critical internal filling pressure for achieving lower frictions at the tube-tube and the tube-foundation interfaces. Under a specified internal filling pressure, there is a critical stacked distance for achieving the minimum tensions and frictions, which corresponds to the most stable stacked structure. © 2015, Central South University of Technology. All right reserved. Source

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