Experimental Researches on Long-Term Strength of Granite Gneiss

Lin Liu,Weiya Xu

doi:10.1155/2015/187616

Abstract

It is important to confirm the long-term strength of rock materials for the purpose of evaluating the long-term stability of rock engineering. In this study, a series of triaxial creep tests were conducted on granite gneiss under different pore pressures. Based on the test data, we proposed two new quantitative methods, tangent method and intersection method, to confirm the long-term strength of rock. Meanwhile, the isochronous stress-strain curve method was adopted to make sure of the accuracy and operability of the two new methods. It is concluded that the new methods are suitable for the study of the long-term strength of rock. The effect of pore pressure on the long-term strength of rock in triaxial creep tests is also discussed.

Highlights

Long-term strength is a key and typical mechanical parameter in rock creep behavior
The microstructure surface morphologies of the samples were obtained as shown in Figure 1 by scanning electron microscopy (SEM) technique
Under lower values of the deviatoric stress, the creep behavior can be divided into two stages, a primary creep stage with decreasing creep rate and a steady-state creep stage at constant creep rate

Summary

Introduction

Long-term strength is a key and typical mechanical parameter in rock creep behavior. The understanding of long-term strength is of great importance for further development of knowledge in the field of rock mechanics [6, 7]. Due to its low permeability and relatively high mechanical strength, granite gneiss is envisaged as one of the potential materials for underground oil storage, CO2 and shale gas storage, and radioactive waste disposal [8, 9]. Martin and Chandler [15] argued that the long-term strength of rock corresponded to the stress at the onset of the microcrack-induced dilation. Chandler [16] further claimed that the long-term strength of rock was defined by the stress at volume strain reversal

Methods

Results

Discussion

Conclusion