Study On Large Deformation Characteristics And Roadway Support Control Technology Of Layered Phyllite

Phyllite is a common rock type in engineering.Its large deformation characteristics make it an influencing factor for the safety and stability of tunnels,shafts and slopes containing phyllite.As the mine enters deep mining,the complex environment of "three high and one disturbance" enlarges the bad characteristics of phyllite,which further leads to problems such as roadway roof fall,sidewall and floor heave,which seriously restricts the mining efficiency and safe production of the mine.Taking layered phyllite as the research object,a series of physical and mechanical property tests of layered phyllite are designed and carried out by means of field investigation,indoor test,theoretical analysis,numerical simulation and engineering test,the strength and deformation characteristic parameters of phyllite are obtained,the failure evolution characteristics of layered phyllite under different loads are analyzed,and the creep constitutive model of layered water saturated phyllite is established,The safety support regulation technology of phyllite roadway is put forward,and the engineering empirical research is carried out.The main research results are as follows:(1)The physical and mechanical tests of layered phyllite are carried out,the physical and mechanical properties and failure characteristics of layered phyllite under different bedding dip angle,water state and confining pressure are analyzed,and the influence laws of different factors on the mechanical properties of layered phyllite are obtained.The results show that under dry and wet conditions,the strength of phyllite first decreases and then increases with the bedding dip angle,showing a Ushaped opening upward.Water has the greatest influence on the degradation of mechanical parameters of 30° and 60° bedding phyllite samples,and the strength and elastic modulus of phyllite decrease significantly after water saturation;When the bedding dip angle is 0° and90°,the peak deformation after water saturation increases.Due to the early failure under the condition of low stress,the peak deformation after water saturation decreases when the bedding dip angle is 30°~60°,and the peak strength increases with the increase of confining pressure under dry and wet conditions.(2)The creep test characteristics of water saturated phyllite under the coupling action of bedding and confining pressure are revealed,and the creep constitutive model of water saturated phyllite is established.The numerical simulation verifies the rationality of the creep constitutive model of layered phyllite.The results show that the elastic modulus and viscosity coefficient of water saturated phyllite samples are in a "U" shape with the bedding dip angle.The confining pressure has a greater inhibitory effect on the creep of the samples with the bedding dip angle of 0° and 90°,while the creep deformation and failure of the samples with the bedding dip angle of 30°~60° are mainly controlled by the bedding.The theoretical curve of the creep constitutive model is in good agreement with the experimental results,and the model is reasonable and effective.(3)A method of steel + soft bolt combination for controlling the deformation of phyllite roadway is developed,and a support technology of phyllite + soft rock saturated roadway is proposed.The results show that the roadway support technology can solve the space-time regulation of large deformation support of layered phyllite and improve the long-term stability of support structure.(4)Taking a mine project as an example,the instantaneous failure characteristics and long-term creep deformation characteristics of phyllite roadway in the project are analyzed,the in-situ stress and loose circle tests are carried out,the roadway engineering support control parameters based on theoretical research are designed,and the empirical research of engineering application is realized.Through the tracking and monitoring verification of the roadway support structure,the combined support method and design parameters of "bolt + buffer layer + steel frame" are adopted.The buffer layer material controls the creep of the roadway to40%~50% of its own thickness,which effectively realizes the migration of the roadway roof compressive stress and reduces the deformation of the steel frame caused by the concentration of roof compressive stress.There are 114 figures,87 tables and 201 references in this paper.