| Hydro-mechanical coupling analysis of layered rocks is widely concerned in many important underground engineering practices,such as deep-buried hydraulic tunnel engineering,nuclear waste geological storage and other typical projects.The hydromechanical coupling research which is consistent with the macro-micro structures of layered rocks is of great significance for the in-depth understanding of the influence of small-scale microcracks and large-scale bedding planes on the hydro-mechanical coupling responses,which is beneficial to accurately simulate the disturbance effects of actual underground layered rocks engineering.In this paper,the hydro-mechanical coupled model and numerical analysis method are proposed according to the macro-micro structures of layered rocks.Through the field water injection engineering and deep tunnel engineering,the influences of characteristics of the macro-micro structures of layered rocks and hydro-mechanical coupling effects on the disturbance effect of underground water injection and surrounding rock engineering are revealed.The main research results of this paper are as follows:(1)At the same time,the proposed models of damage evolution and permeability evolution of layered rocks well considered the mechanisms of damage growth,sliding dilatancy and normal compression of small-scale microcracks,and shear sliding,opening and closing of large-scale bedding planes in process of hydro-mechanical coupling and the weakening effect of water-rock interaction on strength.It can well represent the influences of changes of different scale structures of layered rocks on macroscopic mechanical properties and water flow process.(2)The simulation results demonstrated that the water injection-induced hydromechanical coupling responses,such as damage of surrounding rock,increase of water pressure,bedding plane opening and permeability evolution were affected by different scale structures and orientation of bedding planes as well as different injection flows.The damage distribution and water pressure distribution were ellipsoidal in space,and the expansion region was larger in the direction of larger principal stress.Considering the vertical bedding plane,the injected fluid was more likely to flow along the bedding plane direction,and the size of rock block damage and water pressure increase area in the vertical direction were larger than that in the horizontal direction,and the anisotropy is more prominent.When the injection flow rate increased from 0.2L/s to 0.8L/s,the range of elliptical damage area gradually increased,and the range of water pressure increase area was larger than that of damage area.With the increase of the dip angle from 0°to90°,the range of the block damage area and pressure increase area gradually decreased in the horizontal direction and increased in the vertical direction.The changes of permeability characteristics of layered rock caused by water injection were as follows:the horizontal permeability evolution of layered rock was mainly determined by the permeability of rock block and bedding plane when it was near the injection point,while it was generally related to the permeability of bedding plane when it was far away,and was significantly affected by bedding plane orientation.(3)The simulation results of excavation disturbance in deep buried tunnel engineering showed that the simulation method proposed in this paper could simulate the measured displacement of arch roof and arch waist well.The displacement and permeability characteristics of tunnel caused by tunnel excavation were affected by the hydro-mechanical responses and the orientation of different bedding plane.When the dip angle increases from 0°to 90° without considering groundwater seepage,the maximum horizontal displacement of both sides of arch waist increased gradually,with an increase of 71.55%.The subsidence value at the top and the heave value at the bottom decreased with the increase of inclination angle by 33.81% and 35.75%,respectively.Considering the effect of hydro-mechanical coupling,left and right sides of the horizontal displacement of hance was gradually increasing with the increase of the level angle,the rate of increase closed to 100%,a maximum value at the level at the top of the subsidence angle of 30 degrees,the biggest in at least 90 degrees,and at the bottom of the uplift value decreased with the increase of level,and at the bottom of the deep buried tunnel uplift value was smaller than the top subsidence one times or so.The effect of hydro-mechanical coupling on the settlement value and uplift value of different dip angles was different,and the increase of settlement value was greater than the decrease of uplift value.The permeability evolution of surrounding rock induced by layered deep buried tunnel excavation was affected by the internal macro-meso structures.When it was close to the excavation surface,the permeability evolution of layered rocks was mainly controlled by the permeability variation caused by the damage and propagation of micro-cracks in the rock block.When it was far from the excavation face,the permeability evolution of rock mass was mainly controlled by the permeability change of the bedding planes.The macromeso structures of layered rocks had a significant influence on the engineering disturbance of deep surrounding rock under the condition of hydro-mechanical coupling. |
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