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Qin Y.-Z.,Tongji University | Sun J.,Tongji University | Sun J.,Hangzhou Fengqiang Civil Engineering Research Institute
Yantu Lixue/Rock and Soil Mechanics | Year: 2012

An anisotropic bounding surface model for cohesive soils is developed based on Wheeler's rotational hardening law (S-CLAY1 Model), which is integrated in return mapping algorithm. The UMAT subroutine of the developed model is programmed in ABAQUS software. With the developed model, the numerical simulation of undrained triaxial compression test for normal consolidated kaolin clay (OCR=1) is implemented, and the numerical results of the developed model compared with the Modified Cam-clay model in ABAQUS. The results show that the developed anisotropic bounding surface model could efficiently depict the stress-strain behaviors and change of excess pore pressure of normally consolidated clay. Meanwhile the developed model could reproduce anisotropic behaviors of soft clay under loading conditions. Then the similar numerical simulation for over consolidated kaolin clay (OCR=4) is implemented. The results show that the developed model could also efficiently depict nonlinear stress-strain behaviors of over consolidated clay under small deformation conditions. Source

Sun J.,Tongji University | Sun J.,Hangzhou Fengqiang Civil Engineering Research Institute | Pan X.,Tongji University | Pan X.,Shenzhen Metro Group Co.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2012

A complex mechanical behavior of large squeezing deformation of tunnel weak rocks is discussed under high ground stress condition. The large squeezing deformation can be belonged to the scope of a kind of large deformation rate with slow convergence. On the basis of rheological squeezing deformation's mechanism, a nonlinear 2D visco-elastoplastic constitutive model and a 3D elasto-viscoplastic constitutive model in case of large/small deformations are proposed respectively; and the corresponding secondary development special softwares are studied. The developed material subroutines are applied to analyzing the squeezing problem which occurred in rock excavation for the Wushaoling railway tunnel project. Source

Wang B.,Southwest Jiaotong University | Wang B.,Hangzhou Fengqiang Civil Engineering Research Institute | Wu Z.-K.,Southwest Jiaotong University | Wang Y.,Hangzhou Fengqiang Civil Engineering Research Institute
Yantu Lixue/Rock and Soil Mechanics | Year: 2014

For researching the self-property of yielding anchor cable in the high slope supported, and getting first-hand data of yielding support, the article taking the high slope located in Hongping power plant in Jiangxi province as engineering background, and using a new yielding anchor cable which is produced by Tuqiang Engineering Materials Co., Ltd., field experiments on different length of free section and yielding anchor cable are conducted. Then reveals: Part of the appeared obvious yielding slippage; yielding effect is significant. But the pressure value is great different between tension of orifice and the design of yielding support. It indicated that orifices tension is not as ideal all passed to the anchor cable inside the hole; instead a large part of the orifice tension will be used to overcome the fritional resistance between the anchor cable and anchor hole, And quantity has reached the degree of which is not allowed to ignore. At the same time, test reveals that the length of anchor and free section, number of beam and anchor hole construction quality play a crucial influence on the value of the friction resistance; the longer anchor cable and free section, the more number of beam, the worse the construction quality are, the larger frictional resistance is. And then design focus and further research contents about slope protection by anchor cable in future are put forward. ©, 2014, Academia Sinica. All right reserved. Source

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