The Experimental Research Of Ultrasonic Characterization For Rock Under Uniaxial Load

Ultrasonic testing technique in rock mass medium is a new technique which has been developed during near thirty years.It realized physical and mechanics characters, structure and stress state of rock mass by testing the change of acoustics parameters of sound wave signal after penetrating rock mass,which got recognition in domestic and overseas geotechnical engineering fields.In 2003,my tutor professor FuRonghua and LiuWeiguo Observed the ultrasonic S-wave velocity begins to decrease with the expansion of microcracks rupture in the test about Oil and Gas Reservoir rock mechanics properties. This phenomenon didn't appeared in ultrasonic P-wave,and it was weak in other elastic wave.So,they put forward new idea about study the relation of parameters with the dilatancy of rocks and the ultrasonic S-wave characteristics.Then, This paper compared the parameters ultrasonic S-wave and P-wave in the process of rock deformation .which using the characteristic rocks are very Sensitive to ultrasonic S-wave.Thus providing more reference significance for studing about the elastic limit and Stress strain Features of rock.In this paper,It studied the character about ultrasonic wave transimtion on basalt,limestone,quartz-sandstone and sandstone under the uniaxial compression.The experiment studied effects of elastic behavior, heterogeneous feature ,anisotropy and so on of these rocks by the analyse to ultrasonic parameter and teseted results of rocks. The study results demonstrate:First,The P-wave velocity of rocks is larger and larger along with their densities and compression forces.The S-wave velocity is larger and larger along with their densities on basalt,quartz-sandstone and sandstone.It's exception on limestone.Which change is different from P-wave with compression force changing.It's increase-before-reduce.Which is because that pore with low aspect ratio close easily under low compression.When large pores closed,rocks expressed approaching elastic behavior of theirselves.With compression force increased,closed pore reopen and extend.Which have important effecion to S-wave.The second, The wave crest and through of first period of the P-waveform and S-waveform are larder and larger along with compression forces on basalt,quartz-sandstone and sandstone.On limestone,wave crest is larger and larger along with compression forces.But,wave through is opposite.Which is because that porosity gets lower and most cracks close on rocks under compression forces.And the border of mineral grains contact closely. Whinch result that the lost energy of crack surface and grain border reduce. Ultrasonic transmiss differentliy from other rocks on limestone,this's because limestone disintegrated under compression forces.The third,when ultrasonic transmiss in different bed plane on sandstone,P-wave and S-wave velocity and attenuation have different change. The ultrasonic velocity wave velocity is bigger in vertical sandstone bedding than in the parallel. Ultrasonic S-wave attenuation is larger in the vertical than in the parallel. Ultrasonic P-wave attenuation is less in the vertical than in the parallel. Ultrasonic S-wave velocity is less than ultrasonic P-wave velocity.Ultrasonic S-wave attenuation is larger than ultrasonic P-wave attenuation. So,it is remarkable anisotropy on the same rock.Then, anisotropy is universal existence on underground rocks. The other,coefficient attenuation anisotropy is larger than coefficient velocity anisotropy.Which declare attenuation is more sensitive than velocity to rock anisotropy.It supplied important evidence for researching physical and mechanical property and structure feature of rocks or rock masses by research ultrasonic character on rocks under the uniaxial load. So that it provide the reference evidence and experimental basis of the research of rock dilatancy,rock stability,reinforced rock mass detect, earthquake prediction and so on.