Study on the influence of size effect on rock uniaxial compression test
In order to explore the influence of size effect on the uniaxial compression test of small-size rock samples,the uniaxial compression test of granite rock samples with diameter of 25 mm and different lengths was carried out on the indoor servo testing machine to study the influence of size effect on the mechanical parameters and failure modes of small-size granite rock.The test results show that with the increase of length-diameter ratio,the compressive strength and Poisson's ratio of rock samples decrease gradually,and the elastic modulus increases.Among them,the polynomial model is more suitable for the size effect strength model of small size rock samples;the stress-strain curves of uniaxial compression tests of rock samples with different aspect ratios have different loading trends,and the peak strain decreases with the increase of aspect ratio.With the increase of aspect ratio,the failure mode of rock changes from brittle shear failure to shear failure,and finally gradually becomes brittle failure.The number and angle of failure surfaces of rock samples change regularly.When the aspect ratio is between 1.1 and 2.2,the failure mode of rock samples follows the same failure criterion,and it is feasible to derive the mechanical parameters of rock samples with different aspect ratios by fitting formula.The energy in the failure process of rock uniaxial test is negatively correlated with the aspect ratio,and when the aspect ratio is between 1.9 and 2.2,the change range of each energy tends to be gentle,the failure form of rock sample is relatively uniform,and the difference of its strength in value is small,which can be used as the best aspect ratio of small size rock sample uniaxial test.
granitesmall size rock samplesize effectuniaxial compressive strengthfailure mode
万方数据
维普
