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Dong W.-X.,Tsinghua University | Sun S.-W.,Tsinghua University | Sun S.-W.,Northwest Research Institute Co. of China Railway Group Ltd | Yu Y.-Z.,Tsinghua University | Sun X.,Tsinghua University
Yantu Lixue/Rock and Soil Mechanics | Year: 2011

Large scale triaxial shear tests on rockfill materials were performed to study the characteristics of dynamic moduli, damping ratios and residual deformations of rockfill materials by the large-scale multifunction triaxial apparatus. The dynamic stress-strain relationship and residual deformation of main rockfill, cushion layer and transitional rockfill under cyclic loading are the focuses of this study. The experimental results show that the dynamic stress-strain relationship is sensitive to shear strain level. The dynamic moduli of rockfill material decreases with the shear strain increasing. Confining pressure and consolidation stress ratio are both proportional to the dynamic moduli. From the results of test and model parameters, the dynamic stress-strain relationships and residual deformation can be described reasonably by the modified nonlinear viscoelastic dynamic constitutive models and empirical formula by Shen Zhujiang, respectively. Source


Xiong Z.-W.,China Academy of Railway Sciences | Xiong Z.-W.,Northwest Research Institute Co. of China Railway Group Ltd | Liao X.-P.,China Academy of Railway Sciences | Liao X.-P.,Northwest Research Institute Co. of China Railway Group Ltd | And 2 more authors.
Tiedao Xuebao/Journal of the China Railway Society | Year: 2010

Permafrost slope research has begun from natural slopes mainly in respect of the deformation characteristics, instability mechanism, stability evaluating method and engineering measures on thaw-slumping and gelifuction. It has been discovered that thermal stability of thick ground ice is the key factor of natural slope stability and slope stability in permafrost regions is different from that in ordinary regions. Emphasis is laid on protection and retaining on cutting in thick ground ice sections and on stability of swamping slope embankments and permafrost embankments in heavy grade sections in research of permafrost slopes. Designing and computing methods for retaining walls and anchor slabs are stressed in the field of permafrost retaining engineering. Horizontal frost-heave forces need to be considered in design, the reasonable structure of permafrost retaining walls is the flexible structure; anchor slab design needs to take into account the rheological characteristics of permafrost. Investigation into permafrost subgrade diseases of the Qinghai-Tibet Railway carried out in August of 2007 shows that cutting slopes and escarpment embankments lie in sections of high probability of permafrost subgrade diseases and they are the main threat to the safe operation of the Qinghai-Tibet Railway. Source

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