Writers : Elaheh Hajizadeh Nadaf; Supervisor: Dr. Abbas Abdi, Dr. Abbas Bahroodi; Counsellor: Dr. Manoocher Ghoreshi
Refference : Msc. Thesis
Publishing Year : 1388

Abstract :

Initiation of fracture and factors which leads to it, is one of the issues in which is interest for researchers. In this research with use of numerical modeling method, some of the effective factors in initiation of fracture were investigated. In this regard, the Flac software that is one geomechanical software and usually applicable in continues environment had been used. After understanding the effective concepts and factors in fracturing and investigation of common fractures, forms and different type of fractures, some of tests done on conglomerate layer with using of Flac software. The purpose of this tests was to determine the effect of model length, type and amount of applied stress, effect of scale and primary condition of test (hydrostatic and un hydrostatic). In this tests, compressive stresses on both flank of models monotonously were applied.
Amount of stress is the same in whole of tests and its amount is 50KPa, 1MPa, and 20MPa. Length of models in high scale tests is 600m, 1Km, 2BCm, 3Km and its thickness is 400m. It is worth to mention that low scale models are 100 smaller than models with high scale.
After applying the weight and tectonic stresses on models, investigation of displacement, stress rate and shear strain plots leads us to understand that with increasing the length of model, amount of increase and effects of applied compressive stress in middle of the model will be fewer. In some cases, it is observed that deformation it is the result of weight stress and if the flank of the model to be free, weight stress may be create subsidence and even its related faults. If the primary condition in models be hydrostatic, the strength of rock layers will be less and eventually on the less stress, the fracture will be occurs. Finally in the permanent compressive stresses on the low scale models, the fractures occur before the high scale models. In the other hand, scale will play very important role in condition quantity and quality conditions of the distinct amount of stress.

Subject List : Numerical Modeling