STUDY OF PHYSICAL AND NUMERICAL MODEL IN DETERMINATION OF FRACURE TOUGHNESS MODE I USING THREE POINT BENDING AND BRAZILIAN TEST FOR ANDESITE, LIMESTONE AND CEMENT PASTE.

• Main Author: Aqla, Syarifah
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/78493
• Institution: Institut Teknologi Bandung

Fracture toughness is one of intrinsic property of material that showed the resistance of material when having crack. Fracture toughness can be applied in mining. For example are hydraulic fracturing test and rock fragmentation with blasting. The objective of this research are to study the physical and numerical model in determination of fracture toughness mode I using three point bending and Brazilian test for andesite, limestone and cement paste. To determine the value of fracture toughness mode I, physical model is made and tested by three point bending and Brazilian test. Numerical model is made to observe the failure process of rock sample in laboratory test. For physical test, every sample is made with three rock sample, there are andesite, limestone and cement paste with three different size of diameters. The size of diameter for andesite and limestone are 45 mm, 54 mm and 68 mm. Whereas the size of diameter for cement paste are 44 mm, 55 mm and 70 mm. The shape of rock sample that used for the three point bending test is chevron bend, whereas Brazilian test using the shape of Brazililian disc. The numerical modelling is using finite element method. The result of this research shows that the value of fracture toughness mode I will be larger along with the increasing of rock strengh. In addition, there is no scale effect for every rock sample toward the value of fracture toughness mode I in three point bending and Brazilian test. The difference of fracture toughness value (KIC) of all of rock sample for both test Brazilian adn three point bending test are 0.030-0.630. This result shows that the Brazilian (Guo, et al, 1993) can be used as alternative test to determine the value of fracture toughness mode I at Laboratory of Geomechanics and Mining Equipment, Institute Technology Bandung. Numerical modelling with finite element method shows that rock fragmentation process starting from intersection of V shape crack. This is indicated by decreasing of the strength factor (SF) value on the model with gradual loading rate given.