The Investigation For Scale Effect Of Fractured Rock Mass Based On Damage Tensor

Due to the stochastic structure,fractured rock mass exhibits the properties like heterogeneity,anisotropy and scale effect.And the investigation of scale effect and representative elementary volume(REV)will be helpful greatly to choosing the medium type and determining the mechanical parameters of rock mass.And it is easier that the fractures of fractured rock mass fail than the intact rock.So it is accurate enough and has higher efficiency using the indexes which present the geometric parameters as REV index.Therefore,the relevant literature of REV index were collected and researches about REV indicator representing rock mechanics parameters and structure geometry parameters at home and abroad were summarized.And the investigation and research for selection,solving and application of REV index were carried out as follows:Firstly,the definition of fractured rock mass and the probabilistic and statistical analysis of structure geometrical and mechanical properties were summarized.Based these the the spatial fracture net(SFN)was generated using MATLAB,which could provide figures and data of each structure.Secondly,the SFN was verified through the generation of model,calculation progress and calculation result with that of the real engineering.Based on the SFN,the structure area tensor and structure tensor were calculated and compared,which lead to a new geometrical index with definite physical significance and dimensionless.The new index is volume tensor,which was used to investigate the scale effect and solve REV value.Thirdly,the definition of damage tensor and the expression of rock mass parameter and damage tensor were summarized.The equivalent rock mass model was generated based on the PFC2D and the uniaxial test was simulated to study the simplified equation of damage tensor and structure volume tensor,friction,cohesion and thickness.Then a real engineering was analyzed based on SFN and the equation,damage tensor as REV index,which show that the REV computed by damage tensor is similar with loading method using simulation software and the equation is verified effective.Lastly,for the stability analysis and support of single key block,the theory of probabilistic and statistical is not exact enough.So the damage tensor was used for the block analysis of Xiaopanling slope engineering.And the principle for choosing key block was defined.