Received date: 2016-08-26
Revised date: 2017-01-22
Online published: 2017-05-12
The uniaxial creep test with step loading is carried out for the deep limestone，the axial and radial creep strain of different stress levels are obtained.Based on the test results，the change laws of axial creep strain，radial crcep strain and volumetric strain under different stress levels are analyzed.In addition to，the ratios of the axial and radial creep strain to the total strain are studied，which are defined as the ratio of creep effect Kz and Kh，and the difference between those is Kh-z.The study found that with the increase of the stress level，the axial creep strain and radial creep strain increase first and then decrease.When the constant stress is less than 51 MPa，the sample volume is compressed， Kh-z are within the scope of ±0.28%.It shows that the axial creep effect and radial creep effect are equal.However，if the stress is exceeded，the sample will expand and kz，kh increase rapidly，kh-z increased from 0.21% to 2.64%.It will reach peak value when the creep failure of specimen occurs.The results show that the radial creep effect is more obvious in the expansion stage，compared with the axial creep.The fitting effect is better by describing the characteristics of limestone axial creep with visco-elastoplastic model，and use the method of least squares curve fitting to get the creep model parameters，the average value of R2 is 0.931.
Key words： rock mechanics; step loading; creep experiment; visco-elastoplastic model
XIAO Weijing , CHEN Chen , LI Yongxin , WANG Xiaojun , CAO Shirong , HAN Jianwen . Creep Experiment and Model of Deep Limestone Under Step Loading[J]. Gold Science and Technology, 2017 , 25(2) : 76 -82 . DOI: 10.11872/j.issn.1005-2518.2017.02.076
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