Evolution Characteristics of Shale Rock Microstructure and Mechanical Properties under the Action of Water Softening
The mechanical properties of shale will be greatly reduced under the immersion of rainwater or groundwater,which can easily lead to disasters such as mudslides,tunnel collapse,and landslides.Taking the shale as the research object,the microstructure and mechanical properties evolution of shale under the action of water softening were studied through micro-scopic rock mechanics experiments.The results show that the average and maximum surface roughness of shale increase to 259.1 nm and 561.9 nm respectively after 10 days of immersion.The shale is mainly composed of quartz,chlorite,illite and al-bite,in which chlorite is layered silicate.Under the action of water softening,chlorite disintegrates and releases the expansion force between crystal layers,resulting in an increase in the roughness of shale samples.With the increase of soaking time,the e-lastic modulus of high,medium and low strength minerals decreases gradually.The cohesion of low-strength minerals decreased from 16.7 MPa to 6.0 MPa,while the internal friction angle fluctuated slightly with the soaking time,with an average value of 42.5°.
shalewater softeningmicroscale rock mechanics experiment(micro-rem)nanoindentation test
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