完整-损伤千枚岩各向异性蠕变试验研究
Experimental investigations on creep properties of anisotropic-phyllite in intact and damage state
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摘要: 层状岩体在地壳中广泛存在,开挖破损的层状岩体具有较强的时间效应,深入研究含损伤层状岩体的各向异性蠕变特性,具有重大工程意义。以具有典型层理构造的千枚岩为研究对象,按层理面与主应力方向的关系加工制作成垂直组和平行组二组岩样。采用三轴压缩分别制作含损伤的垂直组和平行组岩样,再采用三轴程控蠕变仪对完整以及含损伤的垂直组、平行组岩样进行不同围压下的分级加载蠕变试验。试验结果表明:(1)蠕变变形量和稳态蠕变速率均随着应力水平的提高而非线性增加;(2)损伤岩样的蠕变变形量和稳态蠕变速率要高于完整岩样,而围压可减小完整和损伤岩样间的差异;(3)稳态蠕变速率随围压的升高而下降;(4)相同应力水平下,垂直组完整和损伤岩样的差异小于平行组;(5)不同围压下,平行组岩样的蠕变变形量和稳态蠕变速率均低于垂直组;(6)平行组的长期强度高于垂直组;(7)损伤岩样的长期强度增长速率高于完整岩样;(8)垂直组岩样长期强度提高幅值高于平行组。Abstract: Layered rock masses are widely distributed in the earth's crust,and it has strong time-dependent effect after excavation and damage.The investigation on anisotropic creep properties of damaged layered rock is significant for engineering applications.In this paper,phyllite with a typical bedding structure was taken as the research object.Samples were divided into two groups according to the relationship between bedding plane and principal stress direction,which was parallel and vertical to the rock bedding plane.The rock samples of vertical and parallel groups containing damages were prepared by triaxial compression,and then the creep tests of intact and parallel groups with damages under different confining pressures were carried out by using triaxial programmed creep tester.The results showed that:(1) Both the creep deformation and the steady-state creep strain rate increased nonlinearly with the increase of stress level.(2) The creep deformation and the steady-state creep strain rate of damaged samples were higher than intact samples,and their differences were reduced by increasing confining pressure.(3) With the increase of confining pressure,the steady-state creep rate had a decreasing trend.(4) The discrepancy between damaged and intact rock of vertical group were less than those of parallel group under the same stress level.(5) Both the creep deformation and the steady-state creep strain rate of parallel group were lower than those of vertical group under different confining pressure.(6) The long-term strength of parallel group were higher than that of vertical group.(7) The long-term strength increasing rate of the damaged sample was higher than that of intact sample.(8) The long-term strength growth amplitude of vertical group were higher than those of parallel group.
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