(1. School of Civil Engineering，Southwest Jiaotong University，Chengdu，Sichuan 610031，China；2. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection，Chengdu University of Technology，Chengdu，Sichuan 610059，China；3. Chengdu Southwest Jiaoda Yaosen Engineering Technology Co.，Ltd.，Chengdu，Sichuan 610031，China)
Abstract：Statistical analysis of crack network in natural rock is the foundation for the studies of rock mechanical properties. The geometry of cracks is closely related to the stress state of rock. Based on the relativity of length and direction of the cracks network，a new parameter which takes into consideration of the length and direction of cracks was proposed and named as the geometry directional coefficient(GDC) . The coefficient can be used to calculate accurately the preferential angle of crack network and then to deduce the random ratio(RR) describing the random degree of cracks networks. The crack network in rhyolite from the tunnel site at Niba Mountain was analyzed. The results indicate that(GDC) and (RR) have clear physical meaning. Based on ，the accurate preferential angle of crack network(PA) can be obtained. Meanwhile，κ can be used to evaluate the random degree of crack network quantitatively. The smaller the ? is，the greater its random degree is. Actually，there is quantitative relationship among(PA) ，(GDC) and (RR) . The results provide an effective method to statistically analyse the complex natural cracks network and the basis to the study of mechanical properties of naturally cracked rock.
2017, Vol. 36 
