Download A VARIABLE PARAMETER BASED CREEP DAMAGE MODEL FOR

A VARIABLE PARAMETER BASED CREEP DAMAGE MODEL FOR ROCK SALT
CONSIDERING THE EFFECT OF LOADING FREQUENCY
Linjian Ma, Qikang Yi, Xinyu Liu, Guoan Wang, Ning Zhang
(State Key Laboratory of Disaster Prevention & Mitigation of Explosion & Impact, PLA University of Science and Technology, Nanjing
210007, China)
ABSTRACT
Laboratory tests were performed to explore the effects of frequency on the deformation property of
rock salt subjected to cyclic loading under confining stress condition. A two-stage (transient and steady)
evolution law of axial cumulative strain was obtained through cyclic stress-strain curves complied from
the loci of minimum load of each cycle. The unloading modulus decreases with loading cycles/time as
a negative exponential function. The damage of rock salt under cyclic loading is reflected by the
degradation of elastic modulus. A unified damage evolution equation considering the effects of
frequency and time was established based on the experimental results (Fig. 1). A new creep damage
model for rock salt was proposed by introducing the non-stationary modular components in Burgers
creep equation according to the Lemaitre equivalent strain theory (Fig. 2). Comparative study indicates
that the new model can accurately describe the creep deformation and damage evolution of rock salt
under different loading frequencies. This paper provides a more reasonable model and relevant
mechanical parameters for the stability analysis of compressed-air storage cavern in the injection and
withdrawal durations.
0.6
0.5
D
0.4
0.3
0.2
f=0.025hz
f=0.05hz
f=0.1hz
Damage evolution equation
0.1
0.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
t/h
Figure 1– Comparison of the unified damage evolution equation with the test data of rock salt under
different loading frequencies
Figure 2– Variable parameter based creep damage model for rock salt based on Burgers rheological
model
KEYWORDS
Cyclic loading, Frequency, Unloading modulus, Damage evolution, Burgers model, Variable parameter
Acknowledgments
This research was financed and fully supported by the National Basic Research Program of China
(973 Program, No.2013CB036005, No.2010CB732003), the National Natural Science Foundation of
China (No.51309234, No. 51308543, No.51309233, No. 51304219, and No.51021001) and the Natural
Science Foundation of Jiangsu Province (BK20130065), which are greatly appreciated by the authors.