Laboratory experimental analysis on performance of heat and frost resistance of three common rocks

In order to acquire the overall change rule of physical parameters,thermal physical parameters and uniaxial compressive strength of different rocks,three common rocks,that granite,sandstone and coal rock from are selected to carry out laboratory experiments with variable temperature including low temperature from 20 ℃ to -30 ℃ and high temperature from room temperature (20 ℃) to 1 000 ℃,and get the main conclusions as follows:① In the changing process within low temperature,phenomenon of water precipitation is more obvious under the condition of high porosity,and thermal conductivity of rock decreases after an increasing process,reaching its peak at -10 ℃,but the uniaxial compressive strength of rock sample increases gradually with the decreasing of temperature;② In the changing process within high temperature,the rate of mass loss increases significantly when the temperature reaches a certain threshold; With the increasing of temperature,the thermal conductivity decreases steadily and shows an approximate linear relationship with temperature;the strength of rock sample decreases gradually with the increasing of temperature,and reduces obviously when reaching its characteristic temperature;③ Rock with compact structure and low porosity has higher natural strength,lower sensitivity to temperature and better heat and frost resistant properties.