Mechanism And Application Research On Splitting Failure Of Layered Slate

The layered rock mass is widely found in slope and tunnel engineering.With the inclination of bedding plane,the rock mass is often under the combined action of pressure,pull and shearing stress.Compared with the compressive and shear strength,the tensile strength is more susceptible to damage,it is very important to strengthen mechanism and application research on Splitting Failure of the layered rock mass.Based on the research project of a purple gorgeous jade mine in Guizhou.The tensile strength,deformation characteristics and failure modes of different layered angles for the layered slate useing Brazilian splitting test.The propagation process and the law of energy evolution were analysed with Particle Flow Code.The results are as follows:(1)The directional distribution of rigid particles weakens the connection between clay mineral particles,which lowers the bonding strength of bedding planes is low.Tensile strength and lateral deformation in center of the disk of slate decreases with the increase of ? nonlinear.They decreases fast between 0° and 30°,then decrease rate gradually slowed down between 30° and 45°,and changes a little between 45° and 90°.The lateral deformation of the center of the disk is greater than the longitudinal deformation.With the increase of ?,lateral deformation increased first and then decreased,and then increased.(2)The failure mode of slate can be divided into four types: the first failure mode is tension destruction of matrix when ?=0°.The second failure mode is shear failure of matrix when ?= 15°and 30°.The third failure mode is shear failure of bedding when ?=45°,60°,75°.The fourth failure mode is tension destruction of bedding when ? = 90°.(3)Initial position of crack and extension direction of crack is changed because of bedding planes.Cracks initiate at center of disk,then expand to both ends along the bedding plane when 45°???90°.Micro-cracks generate at the point nearby bedding plane,but the bedding plane change extension direction of initial cracks,and micro-cracks generate random at bedding plane,then it underlay from bedding planes and formed the macro crack when 0°<?<45°.Bedding planes can cause extension of crack slow down,but can't change extension direction of crack when ?=0°.The total number of micro-tensile and shear cracks can be used for the determination of the mechanism that mainly governed the failure of each specimen.(4)According to the law of energy transfer can determine the position of crack initiation,crack is an important reason for energy dissipation.With the increase of ?,the total absorbed energy,elastic strain energy and dissipative energy dissipation are gradually reduced,the dissipative energy at 0°<?<45°is more than 45°<??90° about ten percent.(5)There exists tension chains along the radial direction between adjacent strong chains,which results in the local tension of the surrounding rock,and the low tensile strength of the rock causes the failure of the surrounding rock in the tensile stress region.Under different angles,the failure modes of the roadway are different,and different support schemes should be adopted.