Experimental Study And Numerical Simulation On Angle-varying Shear Behavior Of Heat-insulated Shotcrete

As the mining depth of coal resources increases,the problem of heat damage in mines is particularly obvious.In order to solve the problem of heat damage in the mine,a new type of thermal insulation sprayed concrete that can isolate the surrounding rock heat is studied.On this basis,this paper studies the influence of dynamic load in the roadway and the effect of high temperature and high humidity on the shear performance of insulated shotcrete.The main research work is as follows:(1)Four different loading rates(1 mm/s,3 mm/s,5 mm/s and 7 mm/s)are used to conduct variable-angle shear tests on insulated shotcrete.The results show that:High,the cohesion of the test piece gradually increases,the cohesion is proportional to the loading rate,and the internal friction angle first decreases and then increases;at loading rates of 1mm/s,3 mm/s,and 7 mm/s When the shear angle of the specimen is 38°,the shear strength is the highest.When the shear angle is 54° under the loading rate of 5 mm/s,the shear strength of the specimen is the highest,and the shear angle is 30° and 62°.,The shear strength is low.(2)Using mass loss rate,wave speed change,electron microscopy analysis and shear strength change value to analyze the influence of heat and humidity cycle on thermal insulation sprayed concrete,the results show that:as the number of temperature and humidity cycles increases,thermal insulation sprayed concrete The quality first increases and then decreases,the wave speed decreases,and the wave speed is inversely proportional to the number of cycles;with the increase in the number of temperature and humidity cycles,the shear strength of the specimen is the highest at a cycle temperature of 40?;when the cycle temperature is 20?,the shear strength is at 28 cycles are the lowest;when the cycle temperature is 40?,the shear strength is the highest in 7 cycles and the lowest is 20 cycles;when the cycle temperature is 80?,the shear strength is the lowest in 3 cycles;in addition,a temperature and humidity cycle is established.The calculation formulas for the influence of cohesion and internal friction angle of thermal insulation sprayed concrete can be used as reference for engineering applications.(3)The RFPA simulation software is used to numerically simulate the shear failure process of the insulated shotcrete.The result analysis:when the shear angle is 30°,38°,46°,54°,the shear failure of the insulated shotcrete is along the The internal ceramsite is damaged;when the shear angle is 62°,the shear failure occurs along the shear line.