Taking the influence of rock weathering damage on slope stability as the research background, the influence of temperature and number of cycles on the physical and acoustic emission properties of the soft mudstone of Jurassic strata in Wanzhou was studied. In this paper, the variation characteristics of acoustic emission signal during mudstone damage are analyzed, and the mechanism of rock weathering damage is analyzed in detail from micro-macro Angle. The research results of this paper provide theoretical and experimental support for rock weathering damage, and the main results are as follows.
(1) The mass loss rate and mass loss rate of mudstone increase under uniform and simulated natural conditions. In the damage process, the mudstone is mostly fracture through failure, and the damage becomes stronger with the increase of the number of cycles, and the crack development is stronger near the heat source than away from the heat source. The higher the water content is, the faster the crack develops and the larger the volume of the caved material is.
(2) With the increase of the number of cycles, the ring count of mudstone with low water content (0-0.1%) has no obvious change. The acoustic emission ringing count with high water content (0.4-0.9%) is divided into two stages, first increasing and then decreasing. The cumulative ring count is divided into two stages, increasing first and then decreasing. lgn value increases exponentially, and R2 increases with higher water content. With the rise of temperature, the ringing count can be divided into three stages: quiet period, peak period and active period. The cumulative ringing number increases exponentially and then gradually stabilizes. Under the simulated heating test under natural conditions, the overall range of ringing count goes through three stages: first decrease, then increase, then decrease. The cumulative ring number goes through three stages: first rise, then fall, and then rise sharply. lgn increases exponentially, and R2 increases as you get closer to the heat source. With the rise of temperature, the ring count experiences three stages: peak period, quiet period and small peak period. The cumulative ring number increases exponentially and then tends to be stable.
(3) When the heating cycle is 0-30 times under simulated natural conditions, the proportion of small-scale microscopic tensile cracks is higher. Then the proportion of shear cracks increases. When the cycle is 30-50 times, the proportion of large-scale and macroscopic shear cracks increases. With the increase of heating rate, the tensile cracks of small scale and micro scale decrease obviously, while the tensile cracks of large scale and macro scale increase.
(4) The variation of b value of wanzhou mudstone can be divided into three stages. At the initial stage of heating, the AE b value of Wanzhou mudstone shows a rapid downward trend. In the second stage, b value starts to fluctuate in a small range, which corresponds to the slow micro-failure of rock mass. In the third stage, when the temperature is about to reach the threshold, b value decreases rapidly.
(5) The main mechanism of wet-thermal fatigue is the change of clay minerals caused by water transport in mudstone, the expansion and contraction of calcite, the decrease of cohesion and internal friction Angle caused by water transpiration and the increase of water pressure, which leads to the weathering damage of rock mass.
谷歌
火狐
