关键词: 扰动荷载, 聚丙烯纤维, 喷射混凝土, 纵波波速, 损伤度, 峰值应力, 能量耗散, 复合材料

Abstract: Based on the test, the safety performance of fiber shotcrete in coal roadway support system under disturbed load is studied. The longitudinal wave velocity and damage degree of the specimen under different disturbance loads and times were measured by non-metallic ultrasonic measuring instrument. The uniaxial compression tests of specimens under different disturbance times are carried out by using the separated Hopkinson compression bar device. The relationship between longitudinal wave velocity, damage degree, peak stress, energy dissipation and disturbance load is analyzed. The results show that with the increase of disturbance times, the longitudinal wave velocity of the specimen first increases and then decreases. The early disturbance will reduce the porosity and increase the integrity of the specimen. With the increase of disturbance times, the damage of the specimen will accumulate, the damage degree will increase, the longitudinal wave velocity will decrease, and the increase of disturbance air pressure will increase the amplitude of wave velocity decrease. When the specimen is subjected to 0.15 MPa disturbing air pressure for 1~5 times, the peak stress is 39.6 MPa, 41.1 MPa, 38.7 MPa, 35.1 MPa and 33.7 MPa, respectively. The increase of the times of disturbance load increases the peak stress of the specimen first and then decreases. The appropriate impact disturbance will increase the peak stress of the specimen. With the increase of the times of disturbance, the decrease of the stress of the specimen increases significantly, and the damage degree of the specimen under the later disturbance load will be greater. The disturbance load will reduce the energy absorption effect of the specimen, and the greater the disturbance load is, the more the action times are, the more obvious the decrease of the energy absorption of the specimen is. In the operation and maintenance of coal roadway support system, the safety performance of fiber shotcrete should be regularly explored to ensure the safety of roadway support system.

Key words: disturbance load, polypropylene fiber, sprayed fiber reinforced concrete, longitudinal wave velocity, damage degree, peak stress, energy dissipation, composites