Rock Mechanics
Mohsen Khanizadeh Bahabadi; Alireza Yarahamdi Bafghi; Mohammad Fatehi Marji; Hossein Shahami; Abolfazl Abdollahipour
Abstract
Complexity of geomaterial’s behavior is beyond the capabilities of conventional numerical methods alone for realistically model rock structures. Coupling of numerical methods can make the numerical modeling more realistic. Discontinuous Deformation Analysis (DDA) and Displacement Discontinuous ...
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Complexity of geomaterial’s behavior is beyond the capabilities of conventional numerical methods alone for realistically model rock structures. Coupling of numerical methods can make the numerical modeling more realistic. Discontinuous Deformation Analysis (DDA) and Displacement Discontinuous Method (DDM) are hybridized for modeling block displacement and crack propagation mechanism in a blocky rock mass. DDA is used to compute the displacements of the blocks, and DDM is used to predict the crack propagation paths due to the specified boundary conditions. The displacements obtained from DDA are converted into stress and considering Kelvin's solution of the problem the crack propagation mechanism within each block is investigated. Boundary stresses are updated due to crack propagation and new stress boundary conditions in DDA. This cycle continued until crack propagation stopped or a new block formed. Numerical solutions of the experimental rock samples including two random cracks with crack 1 fixed and crack 2 created with different angles and one crack with a slope angle of 30 degrees are compared with the existing experimental and numerical results. This comparison validates the accuracy and effectiveness of the proposed procedure because crack propagation paths predicted are in good agreement with the corresponding experimental results of rock samples.
Mohammadhosein Dehghani Firoozabadi; Mohammad Fatehi Marji; Abolfazl Abdollahipour; Alireza Yarahamdi Bafghi; Yousef Mirzaeian
Abstract
In this work, an effective methodology is introduced for simulation of the crack propagation in linear poroelastic media. The presence of pores and saturated cracks that can be accompanied by fluid flow makes the use of poroelastic media inevitable. In this work, involvement of the time parameter in ...
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In this work, an effective methodology is introduced for simulation of the crack propagation in linear poroelastic media. The presence of pores and saturated cracks that can be accompanied by fluid flow makes the use of poroelastic media inevitable. In this work, involvement of the time parameter in crack propagation is of particular importance. The order of doing the work is such that first, derives the fundamental solutions of a poroelastic higher order displacement discontinuity method (PHODDM). Then will be provided a numerical formulation and implementation for PHODDM in a code named linear element poroelastic DDM (LEP-DDM). Analytical solutions use different times to check the correctness and validity of the proposed solution and the newly developed code. The numerical results show a good agreement and coordination with the analytical results in time zero and 5000 seconds . The code is able to pursue crack-propagation in time and space. This topic is introduced and shown in an example.
M. Behnia; K. Goshtasbi; M. Fatehi Marji; A. Golshani
Abstract
Numerical methods such as boundary element and finite element methods are widely used for the stress analysis in solid mechanics. This study presents boundary element method based on the displacement discontinuity formulation to solve general problems of interaction between hydraulic fracturing and discontinuities. ...
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Numerical methods such as boundary element and finite element methods are widely used for the stress analysis in solid mechanics. This study presents boundary element method based on the displacement discontinuity formulation to solve general problems of interaction between hydraulic fracturing and discontinuities. The crack tip element and a higher order boundary displacement collocation technique are used to study the hydraulic fracture propagation and its interaction with the pre-existing cracks and discontinuities in an elastic rock mass. The maximum tangential stress criterion (or -criterion) and the strain energy density criterion (SED) are used to obtain the fracture path and the results of both criteria are compared with each other. The comparison of numerical method with the results brought in the literature shows a good performance of the method in the case of interacting cracks.
