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A New Testing Approach to Evaluate the Role of Unsaturated Stress State Variables and Degree of Saturation of Infill Materials on the Behavior of Infilled Rock Fractures

Dadashi Serej, Ali | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47042 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Khosravi, Ali
  7. Abstract:
  8. Theoretical and experimental studies have shown that natural fractures may exhibit capillary behavior because of either their wall-roughed nature or presence of partially saturated fine materials within the fractures. Different factors are expected to affect the capillary behavior and consequently the hydraulic and mechanical properties of fractures including topology of void spaces in fractures, and state of stress of infill materials and their initial innate conditions (e.g., void ratio, water content, degree of saturation and dry density). Therefore, comprehensive characterization of their hydro-mechanical behavior requires knowledge of morphological details of fracture surface, as well as precise control of the state of stress and degree of saturation of the infill materials. This paper describes the details and typical results from a test method to study the hydro-mechanical behavior of the infilled rock fractures. The test setup is a modified triaxial shear test device that used the axis translation technique for suction control and a flow pump for degree of saturation control. In this testing approach, a pressure transducer was incorporated into a special suction-feedback control loop to establish equilibrium in suction and degree of saturation in the infill material and image processing technique was used to infer dilation of the joint along discontinuity during the test. The results indicated different strength and deformation behavior of the fractures depending on the level of suction applied to the system and the degree of saturation of the infill materials. The specimens subjected to higher values of suction presented higher strength during shear. The effect of matric suction was lower in fractures with smaller infill thicknesses
  9. Keywords:
  10. Image Processing ; Triaxial Measurement Device ; Infill Walls ; Suction ; Pressure Sensor ; Rock Fracture ; Capillary Behavior ; Axis Translation ; Flow Pump

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