Abstract
Mudstone material in a deep roadway is under the coupled stress-seepage condition. To investigate the permeability change and damage development during rock excavation in roadways, a stress-seepage damage coupling model has been proposed. In this model, damage capacity expansion of mudstone material is considered as the initiation and propagation of micro-cracks and the fracture penetration. A damage variable is introduced into the proposed model based on the principle of minimum energy consumption. As a result, an elastoplastic damage constitutive equation is established. Then, the permeability evolution equation describing the micro-macro hydraulic behavior of mudstone is deduced via percolation theory, which can describe the characteristics of sudden permeability change after rock capacity expansion. Furthermore, a finite element model is established based on commercial finite element software-ABAQUS. The numerical model was firstly verified by comparison between experimental and simulation results. On the basis of it, numerical investigation of the temporal and spatial evolution law of pore pressure, damage and permeability coefficient during roadway excavation is undertaken. The numerical results indicate that with increase of construction time, pore pressure first increases and then decreases, while the damage zone and permeability coefficient increase gradually and finally nearly keep constant. The proposed coupling model and finite element method can describe damage and permeability evolution for mudstone material under coupled stress-seepage well.
Highlights
In deep resource exploitation, geothermal resource development, deep tunnel excavation, underground storage of nuclear waste, etc., multi-field coupling problems are involved.Before underground construction, the rock mass has low permeability, and the seepage-stress coupling effect is not obvious
The adjustment and migration of the stress field, seepage field and damage evolution process as well as the interaction among them are very significant, seriously affecting surrounding rock stability in an underground rock project [1,2,3,4]. It is of great theoretical significance and engineering application value for stability control and safety evaluation of surrounding rock in underground engineering to study rock seepage-stress-damage coupling, understand the interaction mechanism of rock mass damage and seepage, and predict the possible damage mode and range of the rock mass [5,6]
Yang [12] proposed a seepage-damage coupling analysis model for the seepage of fractured rock mass to discuss the effect of seepage on the mechanical behavior as well as the effect of stress state on fracture permeability
Summary
Geothermal resource development, deep tunnel excavation, underground storage of nuclear waste, etc., multi-field coupling problems are involved. The adjustment and migration of the stress field, seepage field and damage evolution process as well as the interaction among them are very significant, seriously affecting surrounding rock stability in an underground rock project [1,2,3,4]. Yang [12] proposed a seepage-damage coupling analysis model for the seepage of fractured rock mass to discuss the effect of seepage on the mechanical behavior as well as the effect of stress state on fracture permeability. In the current theoretical analysis of seepage-stress damage coupling [15,16,17,18,19,20,21,22,23], the permeability evolution model cannot describe the characteristics of sudden permeability change after rock capacity expansion. The construction process of a roadway is simulated to validate the effectiveness of the proposed theoretical model using numerical simulation
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