The Secondary Development Of FLAC3D Based On Jointed Rock Mass Damage Model And Its Application

The rock mass in natural environments is a kind of compound damage material which contains two kinds of different scale flaws,such as macroscopic flaws for example joints and cracks and mesocopic flaws for example microcracks and microholes.In the analysis of rock damage,the current research is to considerate these two kinds of damage separately, however, this is inconsistent with the actual situation.Macroscopic flaws such as joints and cracks are developed from mesocopic flaws.The propagation of macroscopic flaws will result in the occurrence of new mesocopic flaws on the other hand.So,there exists a complex interaction between these two kinds of flaws.It requires us to put forward a new constitutive models that can reflect these two kinds of flaws at the same time.The following researches are carried out in this paper based on the viewpoint above:(1) A damage constitutive model considering only mesocopic flaws is established based on tensile strain criterion and Weibull distribution.Taking the joint angle, length, number and other physical parameters and the friction angle, joint cohesion all into consideration,a constitutive model was established for rock mass with macroscopic flaws:According to the Lemaitre strain equivalent hypothesis,the damage variables of two different types of damages are coupled,and then a constitutive model for rock mass by comprehensively considerate the macroscopic and mesocopic flaws is established.(2)Based on the geotechnical simulation software FLAC3 D,using the VC++ language to conduct the secondary development of the constitutive model and generate the dynamic link library which can be called by FLAC3 D.The development process including:defining the base class member function,model registration,data transfer between the model and FLAC3 D,model status indicator and the loading and running of constitutive model.(3)A rock numerical test of uniaxial compression was conducted by FLAC3 D.When the simulated specimens contain a single joint,we can obtain the stress strain curve of the the customized constitutive model and then compare it with the theoretical curve and the simulation curve of the constitutive model of Mohr-Coulomb,to verify the rationality of the constitutive model of custom.When the simulation specimen contains a set of joints,we change the length of the joint,joint angle,number of joints and internal friction angle respectively to verify the effects of changing these parameters on the strength of rock specimen.(4)Finally,an engineering example of tunnel excavation is given.This paper introduces the basic situation of the tunnel and then establish the model of tunnel excavation.We monitor the settlement and deformation of the tunnel during the excavation and compare with the actual monitoring data to further validate the proposed constitutive model.