STUDY OF VISCOPLASTIC STRAIN RATE METHOD TO QUICKLY DETERMINE LONG-TERM STRENGTH OF ROCK
CUI Xuan1，2，SHE Chengxue1
(1. State Key Laboratory of Water Resources and Hydropower Engineering Sciences，Wuhan University，Wuhan，Hubei 430072，China；2. Beijing General Research Institute of Mining and Metallurgy，Beijing 100044，China)
Abstract：A new method to determine the long-term strength of rock with quick creep test is proposed. Firstly，the linear relationship of the viscoplastic strain rate and the loading stress is discussed，and it is illustrated theoretically that only if the viscoplastic strains under different stress levels can be measured，the long-term strength of rock can be determined. And then a method is proposed to separate the viscoplastic strain increment from the total strain increament，in which the creep tests under lower stress are used to establish the viscoelastic creep model to determine the viscoelastic strain increment under higher stress level. Thirdly，the conventional multi-stage creep test for marbles is conducted to check the correctness of the proposed method. And fatherly，the creep test with shortening loading time is also conducted to check the feasibility to shortening test time. The results demonstrate that the proposed method is correct；and under the condition of shortening loading time，the long-term strength of rock is determined correctly showing the feasibility of shortening loading time. These works have demonstrated that the proposed method has the characteristics of quick creep test，computer programming and excluding the personal influence. Furthermore the method can well adapt the fluctuation of deformation measuring values during creep test. It is forecasted that the proposed method will have good application in engineering.
2011, Vol. 30 
