Effects of temperature, water content, hydraulic pressure, stress level and damage on rock creep and the prolonged stability of deep underground structures

As multifunctional structures, deep rock underground structures are built all over the world. Their lifespan is generally expected to exceed a hundred years. However, they are inexorable to rock creep which controls their lasting safety and stability. This article describes the strong factors affecting rock creep and the lasting stability of deep rock engineering, based on pertinent research works. It shows that temperature, water content, hydraulic pressure, stress level, and damage are major factors that significantly affect the creep behavior of host rocks of deep underground structures. Overall, such factors govern the creep life of rocks. Specifically, the increase in these factors causes an increase in the creep strain rate, a shortening of the steady creep phase, an acceleration of the onset of tertiary creep, and thus a shortening of the time-to-failure of rocks. This is due in particular to the fact that fluctuations in these factors disintegrate the internal structure of the rocks and make them increasingly weakened. As a result, the mechanical properties of the rocks are altered and the creep process proceeds at a higher rate than expected. Hence, the creep life of surrounding rocks is reduced, which significantly limits the prolonged stability of underground structures. Appropriate countermeasures, such as long-term monitoring, are strongly recommended.