Study On Shear And Seepage Failure Aging Characteristics And Long-term Stability Of Grouting Reinforced Body In Fully Weathered Granite

With the continuous development and improvement,the construction of tunnels and underground engineering infrastructure has shown a rapid growth in quantity and scale,and more and more tunnels have entered the operation and maintenance period.The long-term stability of the tunnel during the operation period has become an urgent problem,and it is also an important issue related to the normal passage and the safety of personnel vehicles.When constructing a tunnel in fully weathered stratum?fault fracture zone?water-rich and weak stratum such as the quaternary topsoil,in order to ensure the smooth excavation of the tunnel and avoid the occurrence of disasters such as water inrush,grouting method is often used to reinforce surrounding rock.However,after the surrounding rock has been grouted,it is still in a complex geological environment where groundwater and ground stress are long-term effects.The physic-mechanical properties of the reinforced body continue to deteriorate,which leads to a series of disasters such as deformation and damage,leakage and instability of the tunnel during operation.Weathered granite strata are widely distributed in southwestern China and the stratum is highly catastrophic under water-rich conditions.Previous studies have focused on the grouting reinforcement mechanism of fully-weathered granite-rich water-rich strata,and have not fully considered the timeliness of full-weathered granite grouting reinforced body physical and mechanical properties and the long-term stability of surrounding rock.In this paper,the grouting reinforced body of tunnel surrounding rock in the fully weathered granite stratum is studied.Based on laboratory tests and numerical simulations,the mechanical properties of grouting reinforced body are studied,and the behavior of shear permeation damage and timeliness of grouting reinforced body are analyzed,as well as the long-term stability of surrounding rock.It provides some reference and suggestions for the operation of tunnel control and control of fully weathered granite water-rich stratum.The main research contents and conclusions of this paper are as follows:(1)The mechanical properties of various media components of all weathered granite grouting reinforced body(slurry vein,fully weathered granite medium afterconsolidation,and slurry-rock interface)are studied.The cohesive force and internal friction angle of the slurry vein and the fully weathered granite are obtained by triaxial compression test.The effects of roughness and normal pressure on the shear strength and failure morphology of the slurry-rock interface were studied by direct shear test.The cohesion and internal friction angle of the slurry-rock interface corresponding to different JRC were obtained.It is found that the coarse morphology has a great influence on the shear failure zone of the slurry-rock interface.(2)The shear infiltration aging characteristics of grouting reinforced body of fully weathered granite are studied.The rheological properties of the slurry and fully weathered granite were studied by rheological experiments.The failure mechanism of grouting reinforced body is analyzed.The splitting grouting reinforced body are affected by their own heterogeneous structure,which is prone to shear seepage and permeability degradation.On this basis,the shear percolation characteristics of grouting reinforced body is studied by shear percolation test.The infiltration failure law of grouting reinforced body is obtained by accelerated percolation test.With the accelerated percolation test,the law of grouting and solid penetration failure was obtained.(3)The distribution of the slurry veins in the surrounding rock of the tunnel is determined according to the distribution pattern of the slurry veins and the grouting design scheme.Considering the key factors such as the occurrence environment and time effect,based on the strength reduction method,the long-term stability of the tunnel grouting reinforcement ring is studied by numerical simulation method,and the relationship between the deformation of the tunnel structure and the reduction factor under different confining pressures is obtained.And the stability coefficient of the tunnel grouting reinforcement ring is obtained.