A series of triaxial creep tests were carried out on fractured limestone specimens under multilevel loading and unloading cycles to capture elastoviscoplastic strain components. A new data processing algorithm was proposed to analyze the experimental data, determine the instantaneous elastic and instantaneous plastic strain components and the viscoelastic and viscoplastic strain components from the total strain, and separate the viscoelastic and viscoplastic strain curves from the total creep strain curve. The instantaneous elastic strain, instantaneous plastic strain, viscoelastic strain, and viscoplastic strain versus deviatoric stress relationships are highly nonlinear. The proportion of the viscoplastic strain component in the total creep strain increases with increased deviatoric stress. On the basis of the experimental results, a nonlinear elastoviscoplastic (EVP) creep constitutive model was proposed by connecting a Hooke body, a parallel combination of Hooke and St. Venant bodies, a Kelvin body, and a generalized Bingham body. The proposed EVP creep model can describe both the loading and unloading creep behavior precisely. The creep model curves agree very well with the experimental results and give a precise description of the full stages of creep, especially the tertiary creep stage. Moreover, the variation law of the creep parameters is also supported by the experimental observations. So the validity and great practical potential of the proposed EVP creep model are shown well.

Taking a deep-mine horizontal roadway in inclined strata as our research object, the true triaxial simulation technique was used to establish a model of the inclined strata and carry out high-stress triaxial loading experiments. The experimental results show that the deformation of surrounding rock in the roadway presents heterogeneous deformation characteristics in time and space: the deformation of the surrounding rock at different positions of the roadway occurs at different times. In the process of deformation of the surrounding rock, deformation and failure occur at the floor of the roadway first, followed by the lower shoulder-angle of the roadway, and finally the rest of the roadway. The deformation amount in the various areas is different. The floor heave deformation of the roadway floor is the greatest and shows obvious left-right asymmetry. The deformation of the higher side is greater than that of the lower side. The model disassembly shows that the development of cracks in the surrounding rock is characterized by more cracks on the higher side and fewer cracks on the lower side but shows larger cracks across the width. The experimental results of high-stress deformation of the surrounding rock are helpful in the design of supports, the reinforcement scheme, and the parameter optimization of roadways in high-stress-inclined rock, and to improve the stability control of deep high-stress roadways.

In this paper, the large deformation mechanism of deep dynamic pressure roadway is studied from the perspective of the formation and development of plastic zone, and creep and damage of rock mass. The results show that (a) the butterfly‐shaped plastic zone is a nonstable plastic zone, and its unique stress sensitivity and rock formation difference are important causes of disasters such as large deformation of deep roadway. (b) Established a creep model of anchored surrounding rock. Due to the existence of rock mass damage and creep, the range of the plastic zone of the surrounding rock is always dynamic. (c) Explain the mechanism of large deformation of surrounding rock in deep roadway. The source of large deformation of deep dynamic roadway lies in the formation of unstable plastic duct‐shaped zone, and the interference of external factors such as tectonic stress and mining disturbance is the main way to change the plastic zone from stable to unsteady. In addition, the increase in rock mass damage and creep promotes the continuous development of the plastic zone, which eventually leads to the large deformation of the surrounding rock of the roadway. (d) Guided by the deformation mechanism of the surrounding rock in the deep dynamic pressure roadway, the corresponding roadway support technology was proposed for the test roadway, and the better support effect was obtained through the test.

In order to reveal the failure mechanism of the deep roadway under mining‐induced pressure in coal mine, the boundary equations for the plastic zone around the deep roadway were deduced, and then the evolution laws for morphology of the plastic zone and the relationship between the morphological indexes and the stability of surrounding rock were discussed. The results show that, for the deep roadway, the effect of mining on the plastic zone is more sensitive than that on the shallow one. Even if the changes of mining influence are small, they may also cause extremely serious plastic failure of surrounding rock masses, leading to the sudden instability of the roadway. When the plastic wings of the plastic zone are approximately perpendicular to the roof, floor, or sidewall, the large deformation and failure of the deep roadway are very likely to occur. Compared with the index of the uniformity coefficient, the irregular shape coefficient can be used to better characterize the differences in the plastic zone morphology. Finally, a case study was provided to apply the principles for the formation and extension of a butterfly‐shaped plastic zone.

In order to clarify the influence of anchor bolts on the supporting effect of the layered weak roof and surrounding rock of nonlayered roof with good integrity, the mechanical model of the roadway with nonlayered homogeneous roof and layered weak roof was established using FLAC3D. The distribution characteristics of the stress field and the displacement field of the bolt support are analyzed, and the supporting effect of the bolt on the roof of two types of roadways is studied. The research results show that when the original rock stress is not considered, the bolt support shows obvious tensile, compressive stress areas and positive and negative displacement areas in the surrounding rock of the roof of the roadway; when the original rock stress is taken into account, the tensile and compressive stress zones and the positive and negative displacement zones of the anchor support in the surrounding rock of the roof plate disappear obviously. The effect of the bolt support on the stress field and plastic area of the surrounding rock of the two types of roadway roof is not obvious. However, it has a significant effect on suppressing discontinuous deformation such as delamination and sliding between layered roof rocks. The delamination phenomenon between rock layers disappeared obviously, and the range of each numerical curve of the displacement field of the surrounding rock in the anchoring area was significantly reduced. However, the effect of the anchor support on continuous deformation control such as elastoplastic deformation of roof rock of nonlayered roadway is very limited. There is almost no change in the displacement field curve in the depth of the roof‐surrounding rock. Only the shallow surrounding rock displacement field curve range has decreased.

Rocks surrounding deep, high-stress roadways typically undergo a vicious cycle of destruction → repair → re-destruction → re-repair over a long time. This article uses the roadway restoration project of Pingmei Mine No. 6 (400 m underground) as research object. Starting from the plastic area, the characteristics of the distribution of rock surrounding the circular roadway are analyzed, and the influence of the side pressure coefficient, cohesive force, inside friction angle, support strength, and roadway radius on the plastic area is studied. Four types of distribution patterns were observed in rocks surrounding the plastic area of the roadway: round, oval, rounded rectangle, and butterfly. The side pressure coefficient, cohesive force, and inside friction angle affected the distribution and range of rocks surrounding the plastic area of the roadway. The support radius of the roadway and the support strength of its face did not change the distribution of the plastic area, but only affected its size. Therefore, to maintain the long-term stability of weak and broken roadways, the strength of the surrounding rocks must be increased, and roadway renovation should be avoided as it affects the distribution of the plastic area and reduces its scope. Engineering practice has shown that the “anchor net spray + hollow grouting anchor cable” technology for the combined, step-by-step repair and support of roadways, with a hollow grouting anchor cable as core, can suppress the distribution and scope of the plastic area to guarantee safe and long-term use of the roadway.