Abstract
The brittle failure of hard rock due to the excavation unloading in deep rock engineering often causes serious problems in mining and tunneling engineering, and the failure process is always affected by groundwater. In order to investigate the effects of stress paths and water conditions on the mechanical properties and failure behavior of rocks, a series of triaxial compression tests were conducted on dry and saturated sandstones under various loading and unloading paths. It was found that when the sandstone rock samples are saturated by water, the cohesion, the internal friction angle and the Young’s modulus will decrease but the Poisson′s ratio will increase. The fracturing characteristics of the sandstone specimens are related to the initial confining pressure, the stress paths and the water conditions from both macroscopic and microscopic viewpoints. The failure of sandstone in unloading test is more severe than that under loading test, particularly for dry sandstone samples. In unloading test, the energy is mainly consumed for the circumferential deformation and converted into kinetic energy for the rock bursts. The sandstone is more prone to produce internal cracks under the effect of water, and the absorbed energy mainly contributes to the damage of rock. It indicates that the possibility of rockburst in saturated rock is lower than the samples in dry condition. It is important to mention that water injection in rock is an effective way to prevent rockburst in deep rock engineering.
Highlights
The excavation of underground rock engineering is often affected by groundwater [1,2]
It can be seen that the peak strength of sandstone specimen increases as the initial confining pressure increases, but the increase rate slows down with the increase of the initial confining pressure
The difference of the peak strength between dry and saturated sandstones grows with the increasing of initial confining pressure
Summary
The excavation of underground rock engineering is often affected by groundwater [1,2]. Under high geo-stress, high groundwater pressure is prone to cause engineering geological disasters, such as water inrush. It seriously affects the construction progress and personnel safety for underground rock engineering [3]. The excavation of underground engineering, is the triaxial loading and unloading processes of the surrounding rock masses. It is important to carry out the triaxial loading and unloading tests with different water contents of the rocks in laboratory. The statistical and numerical analysis on 14 kinds of the rocks with different water contents were carried out, and it
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