Issue 44

X.-P. Zhou et alii, Frattura ed Integrità Strutturale, 44 (2018) 64-81; DOI: 10.3221/IGF-ESIS.44.06

/ 3 ,  q J 2

 p I 1

Similarly, Micromechanics-based three-dimensional long-term strength criterion (33) can be rewritten in another form:

(37)

3

2

2

2

 F f

 q f pq f q 



 pq f p f q f p   

f

0

1

2

3

4

5

6

7

where

                           f f f f f 1 2 3 4 5 3 4 1 3

4 cos





 3 2



2

 

 

 3 2 cos n



 m n







sin











2

 m n



cos







f

(0)











 n m n 



 2 3             m m n n m mn n n 3 6 2 2 6 2 2 2    

 

iu



 3 2 2

 c





s

cos 2

sin 2





iu f t

0 ( )

f

(0

)

2 3



 m n s 





 3 2



.

iu

 

 





 m n

 c





n

3

2

cos

si

n





iu f t

0 ( )

f

(0

)

2





iu

  

 c

m n s

iu f t (

)

0

f

0 ) ( ) (0

1





 3 2



2

2

iu

 

 

 3 4 cos n



 m n

 c





f

s

si

n





6

iu f t

        f 7 3

f

(0)

 s m n

2

2

iu

 c

iu f t (

)



0

C OMPARISON WITH THE EXPERIMENTAL DATA OF COAL

S

eries of triaxial compressive experimental data were obtained from creep tests on various rocks by Refs [25-27]. The long-term uniaxial compressive strength of rocks and the fitting strength parameters are listed in Tab. 1. Tabs. 2-4 show theoretical strength and the experimental data of Barre granite, Inada granite and Jinping marble. Figs 5-7 show that comparison of predicted strength and the experimental data of Barre granite, Inada granite and Jinping marble. It is found from Tabs 2-4 and Figs 5-7 that the proposed long-term strength criterion agrees well with experimental data of different rocks.

The fitting strength parameter (n)

The fitting strength parameter(m)

Long-term uniaxial compressive strength

The strength parameter(s)

Rocks

Reference

1 1 1

Kranz [25]

Barre granite Inada granite Jinping marble

6.709 1.000

0.737 0.101

158 216

Maranini and Brignoli [26]

Yang et al. [27]

12.184

18.566

80

Table 1 : The fitting strength parameters and uniaxial compressive strength of different rocks.

76