Study of practical approach to assess integrality of engineering rock mass

The integrality of rock mass is assessed based on the geometrical character and cementing status of structural plane, in which the structural plane statistic method and cementing status recognition method are used together. The geometrical character of structural plane is assessed according to volumetric joint count, and the geometrical integrity index of rock mass (I-g) is introduced to represent it. The cementing status of structural plane is classified into five grades based on joint opening and cemented fills. The qualitative character of each grade is given; and the cementing status coefficient of structural plane (I-p) is introduced to represent it. Then the integrality index of rock mass (I-rm) is defined as I-rm=IgxIp. The integrality of rock mass is classified into five grades: integrated, moderate integrated, cracked, moderate cracked, and highly cracked. The qualitative character and Irm of each grade are given. Taken a highway tunnel for example, the integrality of surrounding rock mass of tunnel is assessed by the sound wave test method, the volumetric joint count method and the method suggested in this article respectively; then the assessment results are compared as well. It is found that Irm obtained with the method suggested in this article coincides with K-v gained by sound wave test method, while the results of volumetric joint count method are commonly higher than the sound wave test method.