Study On The 3D Block Contact Algorithm Based On The Volume And Its Application During The Failure Processes Of Cavern Surrounding Rock

With the rapid development of deep resource exploitation,the related disasters are especially prominent.In view of advantages of the numerical method,it is an urgent problem to develop a three-dimensional continuum-discontinuum method which can reflect the transition from the continuous medium to the discontinuous medium.In this thesis,the three-dimensional crackable Lagrangian element method suitable for simulating the deformation cracking processes of rock materials is used to simulate the deformation and tensile cracking processes of specimens in uniaxial tension and three-point bending.The effects of I-type fracture energy,rock specimen height and elements size are analyzed.The present results are compared with the theoretical and numerical solutions,and the correctness of the method is verified.The hexahedral block is the main research object,and a three-dimensional block contact algorithm based on the volume is proposed.The algorithm consists of two parts: the hexahedron block contact detection method and the contact force calculation method based on the volume.The algorithm is introduced into the three-dimensional crackable Lagrangian element method,and a three-dimensional continuum-discontinuum method based on the volume is obtained.The method is used to simulate the collision test and slide-collision test of hexahedron block.For the collision test of hexahedral block,the displacement,velocity,normal contact force and movement processes of hexahedron blocks are analyzed.For the slide-collision test of hexahedral block,the movement processes and the change of contact forms of hexahedral blocks are analyzed.In the collision test of hexahedral block,the present results are compared with the theoretical solutions,and the correctness of the proposed algorithm is verified.Meanwhile,deformation-cracking-motion processes of rectangular cavern surrounding rock under different lateral pressure coefficients(0.5-1.5)are simulated.With the increase of the lateral pressure coefficient,the depths of tensile zones of the roof,floor and two sides of the cavern increase,and the depths of two sides of the cavern is gradually larger than those of the roof and floor.Positions of compressive zones near four corners of the cavern gradually shift from two sides of the cavern to the roof and floor;positions of elements separated from the surrounding rock change from two sides of the cavern to the roof and two sides,and then to the roof and floor;when the distribution range of the V-shaped notches on the roof and floor of the cavern gradually increases,the distribution range of two sides basically remains unchanged.With the increase of the lateral pressure coefficient,the final displacements of the roof and floor of the cavern decrease,and those of two sides increase.The number of nodes separated of the roof,floor and two sides of the cavern decreases with the increase of the distance away from the surface of the cavern.With the increase of the lateral pressure coefficient,the number of timesteps corresponding to the initial failure of cavern surrounding rock decreases,the number of failure times increases,the final failure range increases,and the longest distance between the separation node and the surface of cavern decreased,followed by an increasing tendency.There are 77 figures,1 table and 90 references in the thesis.