Experimental Study On Mechanical Properties Of Migmatite Under Cryogenic Freezing

With the geotechnical engineering in the frozen regions and the artificial freezing engineering are going on,the surrounding rock in the cold regions is being effect of low temperature of cyclical action or frozen state,the difference of mechanical property between low temperature and normal temperature has been draw people's great attention.It is important to further study the strength characteristics of the frozen-rock for ensure the safety of engineering.The study focus on the migmatite from Anshan area.Selected two kinds of rock,saturated and dry,carried out a uniaxial and triaxial compression experiment.Through experiments,the mechanical properties and deformation characteristics of these two kinds of rocks under different freezing temperatures and confining pressure were analyzed.The main work of this paper is as follows:(1)In the triaxial text,the migmatites' axial peak stress increases linearly with the rise of confining pressure.Under the ambient conditions,the axial peak stress direction of sample increased by 130% with the confining pressure increases from 0Mpa to 6Mpa.When the temperature is-5?,the peak stress rose by 129% and it's increased by 155% when-20?.These two kinds of state of the sample's elasticity modulus is increases parabolic in the process of decrease in temperature.And the waterlogged sample growth clearly.The Poisson's ratio constant drop with the temperature fall and the overall extent are not big.The migmatites' cohesion increases linearly with the decrease in temperature.The internal friction angle increases slightly when the temperature reduce.(2)The migmatites' axial peak stress are regularity increase when the temperature deceased for both saturated and dry.The migmatite of saturated is more sensitive to temperature and the axial peak stress is growing faster with the process of temperature decreased.The peak stress of saturated is greater than dry for both uniaxial and triaxial compression tests,and the migmatite of saturated have higher strength in subzero temperature than room temperature.(3)In the aspect of disruption characteristic,the failure mode of migmatite is splitting failure that parallel to the axial approximation in uniaxial compression test.In triaxial compression test,it is shearing failure.Under lower confining pressure,it is shearing failure of the macro single section basically,and the surface of fracture is more smooth with the temperature decreased.