Experimental Study On Shear Strength And Permeability Of Granite-Mortar Interface

In the project of diversion tunnel,dam and nuclear waste address storage,it is necessary to rebuild new surrounding rock on the original rock mass.The interface between the original rock mass and the surrounding rock is the structural fragile surface,and the interface is under stress.The field,seepage field and part are also in the multi-field coupling environment of the thermal field.Among them,the interface is most affected by the shear stress received in the stress field.Under the action of shear stress,the interface slips and collapses easily at the interface.Destructive behavior,therefore,the mechanical properties of the interface and the change of permeability of the two-phase dielectric material under the coupling of shear stress and seepage field are of great significance for analyzing the stability of the engineering interface.In this paper,the granite cement mortar samples are determined by selecting the cement mortar samples with different water-cement ratios to determine the influence of the water-cement ratio of the cement mortar(0.5 water-cement ratio,0.3 water-cement ratio)on the interface,and then passing the muffle furnace to specify After the temperature is heated to the specified temperature(25°C,150°C,250°C)and then stabilized for a period of time,then the temperature is lowered to the normal temperature at a specified rate to determine the effect of the heat treatment on the interface.By using a self-made gasket,temperature-seepage-stress-chemistry(THMC)is utilized.The multi-field coupling test system for geomaterials is used to test the shear seepage coupling under different confining pressures(5、10、15 and 20MPa).The density and porosity of the granite/cement mortar samples after heat treatment were measured,and the specific surface area,pore size and pore volume of the cement mortar samples after heat treatment were analyzed.Based on this,the interface of the granite/cement mortar sample was sheared.Strength and permeability tests,from the macroscopic view of the analysis of the evolution of the interface shear strength and permeability,the main conclusions are as follows:(1)The water-cement ratio affects the shear strength and permeability of the interface of the granite/cement mortar sample.The shear strength of the interface of the 0.3 water-cement ratio granite/cement mortar sample is greater than 0.5 water-cement ratio sample;0.3 water-cement ratio granite The overall trend of the interface permeability of the cement mortar sample is greater than 0.5 water-cement ratio sample;(2)The shear strength of the granite/cement mortar interface increases with the increase of normal stress.The permeability of the interface decreases as the normal stress increases,and the tendency of the permeability decreases as the normal stress increases.Studies have shown that the effect of normal stress on the interfacial permeability of granite/cement mortar samples is greater than the water-cement ratio and heat treatment temperature;(3)Granite/cement mortar samples after heat treatment,the density of the sample decreases with the increase of heat treatment temperature,and the porosity increases,and the porosity of the sample changes after treatment at 250 °C;the cement after heat treatment For the mortar sample,the specific surface area decreases with the increase of the heat treatment temperature,and the pore volume and pore diameter increase.The 0.5 water-cement ratio of the cement mortar sample after heat treatment is larger than the 0.3 water-cement ratio,and the 0.3 water-cement ratio The diameter of the hole of the cement mortar sample changes greatly after heat treatment;(4)With the increase of heat treatment temperature,the shear strength,internal friction angle and cohesive force of the granite/cement mortar sample interface are gradually reduced,and the interface permeability of the granite/cement mortar sample with a temperature of 0.3 water-cement ratio is The effect is greater than 0.5 water-cement ratio sample;(5)The stability trend of the permeability of the granite/cement mortar sample after the interface failure is affected by the heat treatment temperature.The time required for the permeability of the interface at the granite/cement mortar sample to be finally stabilized increases as the heat treatment temperature increases.The water-cement ratio has no obvious effect on the stability trend of the permeability of the granite/cement mortar sample after the interface failure.