Master's Degree Thesis ISRN: BTH-AMT-EX--2011/D-15--SE Land Sliding Analysis on Red Clay Soil using Fracture Criteria Mohamed Riyazdeen M.G Yisho ji Jin ji Department of Mechanical Engineering Blekinge Institute of Technology Karlskrona, Sweden 2011 Supervisor: Sharon Kao-Walter, BTH Land Sliding Analysis on Red Clay soil using Fracture Criteria Mohamed Riyazdeen M.G Yisho ji Jin ji Department of Mechanical Engineering Blekinge Institute of Technology Karlskrona, Sweden 2011 Thesis submitted for completion of Master of Science in Mechanical Engineering with emphasis on Structural Mechanics at the Department of Mechanical Engineering, Blekinge Institute of Technology, Karlskrona, Sweden. Abstract: In order to assess the safe and functional design of road ways, buildings, bridges, dams, etc. Also to protect from structural damages and geological disasters. The landslide analysis is to conduct based on force resisting method by applying uniform loads on top of the hill to determine slope stability, instability, for with and without crack on clay soil is to be experimented and evaluate the mechanical properties such as elastic modulus, poison ratio, and shear strength. In addition, the numerical model is implemented to the crack initiation model such as tensile, bending and shear to identify the fracture behavior for Mode I and Mode II and determine the criteria of a stress concentration factor [Kt], stress intensity factor [KI], and crack mouth opening displacement values are analyzed theoretically and verify using ABAQUS. Experimental model shows good agreement with the simulation result. Keywords: Slope stability, Geological disaster, Stress intensity factor, Land slide, Crack initiation, structural damages. 1 Acknowledgement Our deepest gratitude goes to Dr. Sharon Kao-Walter, our supervisor, for her constant encouragement and guidance. She has walked us through all the stages of this thesis. Besides that, we also want to thank to Huang Ying, professor at Kunming University of Science and Technology, China. Prof Huang has guided and supported in Experiment. Special thanks to Lic.Sc. Leon, Armando for guided in application of ABAQUS FEM method. Last, our thanks would go to our beloved family for their loving considerations and great confidence in us all through these years. We also owe our sincere gratitude to our friends and classmates who gave us their time in listening and helped us work out during the difficult course of the thesis. Karlskrona, November 2011 Mohamed Riyazdeen M.G Yisho ji Jin ji 2 Abbreviation 3PB 3 point bending test CMOD Crack mouth opening displacement SENT Single edge notched test SENB Single edge notched bend SF Safety Factor SIF Stress Intensity Factor 3 1. Notations Crack length Thickness of the Specimen in mm []D Elastic stiffness matrix or stress-strain matrix Young‘s modulus for plane strain and Plane stress Geometric function G Shear modulus Area moment of inertia about neutral axis x J J-Integral Stress Intensity Factor Stress Concentration Factor K (a) Stiffness L Length of the beam (mm) The moment about neutral axis P Force (N) S is the span length of beam Crack mouth opening displacement v Poisson‘s ratio W Width of the beam (mm) Perpendicular distance from the neutral axis 4 Stress component Total strain vector, Thermal strain vector Deflection in mm 5 Contents Acknowledgement ................................................................................................. 2 Abbreviation .......................................................................................................... 3 1. Notations ........................................................................................................... 4 2. Introduction ....................................................................................................... 8 2.1 Aim and Scope ................................................................................................... 9 2.2 Background Research ........................................................................................ 9 3. Theory ............................................................................................................. 13 3.1 Stress-strain ..................................................................................................... 13 3.2 Three Point Bending ........................................................................................ 15 3.3 Simply supported beam ................................................................................... 15 3.4 Shear and Moment Diagram ........................................................................... 16 3.5 Bending Stress ................................................................................................. 17 3.6 Crack Initiation ................................................................................................ 17 3.7 Stress Intensity Factor ................................................................................ 17 3.8 Three Modes of Failure .................................................................................... 18 3.9 Geometric function .......................................................................................... 19 3. 10 J –Integral ..................................................................................................... 20 3. 11 Crack Mouth Opening Displacement ............................................................ 20 4. Analysis of Fracture Criteria ............................................................................. 23 4.1 Stress concentration ........................................................................................ 23 4.1.1 Stress concentration for circular holes .................................................... 23 4.1.2 Stress concentration for elliptical holes ................................................... 31 4.2 Stress Intensity Factor ..................................................................................... 39 4.2.1 Single Edge Notch Tensile ........................................................................ 39 4.2.2 Single Edge Notch Bend ........................................................................... 41 4.4.3 Shear Model Test ..................................................................................... 45 6 4.3 Numerical Results ............................................................................................ 47 4.3.1 Simulation Result for Stress concentration.............................................. 47 4.3.2 Simulation Result for Stress Intensity Factor ........................................... 51 5. Experimental Work .......................................................................................... 55 5.1 Present situation of landslide .......................................................................... 55 5.2. Experimental Setup ........................................................................................ 57 5.3 Slope-forming process ..................................................................................... 59 5.3.1 Experimental slope formation method ..................................................... 59 5.3.2 Experimental slope formation process .................................................... 59 5.4. Experimental development............................................................................. 61 5.4.1 Implementation of the load ....................................................................... 61 5.4.2 Observation of the experiment process .................................................. 62 5.4.3 The judgment of experiment finished ..................................................... 62 5.5 Experiment results and analysis ...................................................................... 63 5.5.1 Indoor landslide experiment validation ................................................... 63 5.6. Determine the model parameters .................................................................. 64 5.6.1 Determine of Poisson's ratio .................................................................... 64 5.6.2 Determine of Elastic Modulus .................................................................. 65 5.6.3 Determine of Shear Strength ................................................................... 66 5.7 Landslide simulation and experiment validation ............................................. 68 6. Conclusion ....................................................................................................... 73 7. Future Work ..................................................................................................... 74 8. References ....................................................................................................... 75 Appendices: ......................................................................................................... 78 ABAQUS File .......................................................................................................... 78 Ansys file................................................................................................................ 94 7 2. Introduction The phenomenon of cracking and damage simulation is a popular research concern. Materials have different damage phenomena. Rock and concrete are quasi-brittle material. The cracking zone created the formation and performance of shear bands of flexible material production, brittle materials for the formation of discrete cracks. Since 1960s, a series of dams, bridges and road accidents