Understanding of the effect of chemical solutions on hydro-mechanical properties of rocks is important in many fields of rock engineering. The bearing capacity and settlement values of rock foundation nearby the heap-leaching mineral processing sites are controlled by deformability parameters and strength of rocks during the chemical dissolution of minerals. The purpose of this thesis is evaluating the effects of sulfuric acid solution used in leaching of copper metal on hydro- mechanical behavior of rock mass, under heap leaching installations and better realization of chemo- hydro- mechanical coupling processes related to this phenomen. A set of laboratory experiments are conducted for evaluating the influence of sulfuric acid with different pH values of 1, 3 and 5; on properties of andesite rocks and rock joints in Darezar copper mine. The values of dry and saturated density, percentage of porosity, percentage of water absorption, uniaxial and triaxial compressive strength of saturated intact rocks and also shear strength and joint roughness of rock joints, in different sulfuric acid concentration are measured. Also using Discrete fracture network - Distinct element method approach, the effect of leaching chemical solution on permeability of fractured rock mass is also evaluated. The results show that with decreasing pH value of sulfuric acid solution, dry and saturated density and whole mechanical properties of intact rock is decreased, while percentage of porosity and water absorption are increased. On the other hand, as a result of chemical reaction, shear strenght of rock joints decreased and ductile behavior of rocks become significant. Furthermore, roughness of joint surfaces does not follow a unique trend. The reason of this phenomenon is the effects of several other parameters on the roughness of rock joints, as thickness and strength of joints filling materials. The numerical Discrete fracture network - Distinct element modeling results show that with decreasing pH value of copper metal leaching solution, the coefficient permeability tensor are increased.
