Study On The Nonlinear Joint Model And Its Engineering Application

During the long geological history,the rock mass underwent complex geological transformation.So there are many kinds of structural planes in the rock mass,such as faults,weak intercalated layer,joints,fracture and so on.The integrity and the strength of the rock mass are decreased due to the large structural surface of the rock mass.The rock mass is composed of structural plane and the rock.In the analysis of stress and deformation of rock mass,the structural component is larger than the rock.Due to the structural surface,the mechanical properties of the rock are characterized by discontinuity,anisotropy,inhomogeneity and inelasticity.The nonlinear deformation characteristics of joints under stress directly affect the joint opening,contact area and strength,and the stability of rock mass engineering.Because of the discontinuous characteristics of rock mass in material and structure,it is great significance to study the deformation characteristics of joints and construct a reasonable joint model when simulating the deformation and stress distribution of rock mass.Based on the 3DEC program and the existing research results of joint deformation characteristics,the deformation characteristics of the joint are analyzed,and the appropriate joint model is selected and improved.In this paper,combined with 3DEC program and the existing results of the joint deformation characteristics,research the joint deformation characteristics,and improve the joint model.Based on this,combined with the interface provided by 3DEC,a new joint model is introduced and compiled.The numerical simulation test and the engineering analysis were carried out in the 3DEC program.The main research results are as follows:(1)The normal deformation characteristics and the peak shear strength of joints are analyzed.Furthermore,a new joint deformation model is designed in 3DEC program.Based on the User-defined joint constitutive models interface provided by 3DEC,Using C++ to write the DLL file of joint constitutive model which is embedded in the 3DEC.(2)The numerical simulation program of uniaxial compression test and direct shear test is written by FISH language and corresponding command of 3DEC.The results of multi group normal uniaxial compression test and direct shear test results of the sandstone joints are similar to the test results.And it is an effective method to use C++ language to write the joint model.(3)Taking the left side slope engineering of Jinping I hydropower station as an example,3DEC is used to construct the three-dimensional model,to analyze the stability of the slope excavation of the spandrel groove.A new joint model is used to calculate the 4 groups of joints and the deep fracture SL44-1.Through the simulation analysis of slope excavation,the correctness of the new joint model is further verified.(4)The numerical results show that the deformation caused by excavation is the rebound deformation of free surface mainly,and is concentrated in the vicinity of the fault F5.There is a subsidence deformation zone above the excavation face.The maximum value is near the F5 fault.The block enclosed by F42-9 which is used as the bottom slip surface,the X which is the cutting edge of the trailing edge and the deep fracture SL44-1 which is used as the cutting surface of the lateral margin has great influence on the slope stability.