Experimental Analysis on Creep Properties of Frozen Silty Mudstone Considering Conservation of Energy

Abstract The artificial ground freezing method is a dominant technique during the construction of massive coal mines and tunnels. The comprehensive understanding of creep properties, especially the accelerating creep process of frozen soft rock, can provide significant guidance regarding the excavation of the soft rock layer. In this article, a series of uniaxial compression tests and creep tests of silty mudstone samples was conducted. In conjunction with the experimental data, the creep properties of frozen silty mudstone at transient, steady, and accelerating creep stages are discussed in detail. Furthermore, based on the conservation of energy, a winding element is introduced to modify the classical Nishihara model, which reveals that the modified Nishihara model not only presents the creep-damage properties of frozen silty mudstone at the accelerating creep stage but also describes the primary and stationary creep stages accurately. Moreover, the fitted results using the modified Nishihara model are in good agreement with the test results. Ultimately, the results of sensitivity analyses corroborate that small changes in the stress level can cause large changes in the failure time. At the accelerating creep stage, the axial strain rate increases more rapidly when the coefficient winding element is small, causing a shorter time to approach failure. This modified creep model can present a theoretical basis for further revealing the objective law of rock creep and can provide an important reference for the safety assessment of coal mine and tunnel construction using the artificial ground freezing method.