In order to reveal the mechanical response of surrounding rock of karst tunnel under stress-damage-seepage coupling effect, a new damage constitutive mechanical model of surrounding rock of karst tunnel under stress-damage-seepage coupling effect is established, which is calculated by the COMSOL Multiphysics in this paper. When the mechanical parameters are assigned to microelements of rock mass by the Weibull distribution function, the larger the m value is, the more homogeneous the rock mass is. The variation trend of strain energy density with m is similar to equivalent stress, which increases firstly and then decreases. The number of damage points increases with the increase in loading step and decreases rapidly after reaching the peak value and then remains a small number in the later loading stage. With the increase in γ , the stress range expands to the rock mass above the vault and below the floor; the stress value increases significantly, and the surrounding rock of karst tunnel is closer to strength limit, leading to the damage of rock mass. With the increase in γ , the area of the damage area in the upper part of the vault becomes larger, and most of the rock mass below the bottom plate is damaged; the damage area is semicircular, which indicates that both places are damaged by shearing action, resulting in the developed fissures. Besides, there are the distribution characteristics of “high value on both sides with a peak value and low value in the middle position” in the permeability distribution, and high permeability is located at the arch foot, and the low permeability is located at the floor. The larger the value of γ , the larger the permeability. The research achievements provide an important theoretical basis for prediction and treatment for dynamical disaster of karst tunnel.
The surrounding rock of deep roadway is mostly composed of fractured rock. The deformation of roadway surrounding rock is complicated, which not only involves the stress change, but also involves the support means. This paper aims to study the deformation and fracture evolution law of surrounding rock in deep underground engineering. According to the stress rebalancing characteristics, after roadway excavation, the development and evolution characteristics of surrounding rock cracks are studied. At the same time, different seepage zones are divided according to the relationship between surrounding rock failure and its total stress–strain, that is, complete seepage zone, seepage shielding zone, and proto-rock seepage zone. The crack distribution characteristics of surrounding rock are studied, and the graded control of gradient support is proposed. In the broken area, the gradient bearing shell outside the roadway is achieved by means of bolting and high-strength grouting. As the cracks and pore sizes in the plastic zone gradually decrease along the radial stress direction of the roadway, and the open cracks gradually change into closed cracks, it is difficult for ordinary grouting materials to complete better consolidation and filling. Therefore, small particle size grouting reinforcement materials are studied. The plastic zone (fracture zone) is reinforced with nano-scale grouting material, and the internal three-dimensional gradient bearing shell is formed by combining with the anchor cable. This research plays an important guiding role in the stability of deep roadway surrounding rock.
When the collapse column of overburden is disturbed by the working face, the grain loss in the karst collapse column occurs by the dissolution and corrosion of groundwater, thereby inducing the water inrush disaster. The test samples are prepared based on the fractal theory and the Talbol grading theory, and the seepage evolution law of fractured rock in collapse column under triaxial stress is studied, by employing the triaxial seepage test equipment. Besides, the seepage mechanics model of broken rock is established and calculated in the COMSOL Multiphysics, and the water-conducting channel under mass loss condition in the collapse column is further elucidated. The research results indicate that the loss ratio of mass is inversely proportional to the Talbol power index, and grain mass loss rate increases with the decrease of the Talbol power index. During the infiltration process, the evolution of pore structure is related with grain size distribution. With the increase of the Talbol power index, the overall porosity increases. Grain loss is an internal factor in seepage loss stability. Flow speed is accelerating, and seepage pathways are communicated with each other to induce the water inrush disaster.
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