酸环境干湿循环作用下泥灰岩损伤劣化分析

DAMAGE AND DETERIORATION ANALYSIS OF MARL UNDER DRY WET CYCLE IN ACID ENVIRONMENT

针对库区消落带泥灰岩的最不利作用环境——酸环境干湿循环下力学性质损伤劣化问题,以岸坡泥灰岩为研究对象,分别开展pH=3,5,7溶液条件下的干湿循环试验,分析了酸环境干湿循环作用下泥灰岩单轴抗压强度的劣化规律,查明了其对泥灰岩力学性质的损伤劣化特性,采用颗粒流软件对比探究了不同循环次数对力学强度参数的影响规律,并结合库区消落带岩体劣化现象分析了层进劣化机理。研究结果表明:pH=3,5,7溶液环境下泥灰岩单轴抗压强度变化均与干湿循环次数呈反比关系,累积劣化度Sn在34.79%~54.31%之间变化,且呈现快速上升、缓慢发展、趋于平稳的变化趋势,而峰值应力劣化范围为8.79%~35.61%;泥灰岩黏聚力C、内摩擦角φ、弹性模量E均随干湿循环次数的增加而不断降低,且损伤劣化以圈层渐进的模式进行;库区消落带岩体受到酸溶液干湿循环作用后,附近岩体会萌生大量次生裂隙,随着循环次数的推进及损伤的持续累积,裂隙逐渐贯通并向坡内层进扩展,扩展范围和速率与干湿循环次数和溶液pH值有关。以上分析结论与规律可为库岸山体滑坡崩塌失稳、库区危岩基座软化、蓄水渗漏等灾害的预测与应急防治提供科学依据和理论方法。

Aiming at the most unfavorable environment of marl in the fluctuating zone of the reservoir area—the problem of damage and deterioration of mechanical properties under dry-wet cycle in acid environment,taking bank marl as the research object,the dry-wet cycle tests under the condition of pH=3,5,7 solution were carried out respectively,the deterioration law of uniaxial compressive strength of marl under dry-wet cycle in acid environment was analyzed,and the damage deterioration characteristics of marl to mechanical properties were found out.The influence law of different cycle times on mechanical strength parameters is explored by using particle flow software,and the mechanism of stratification deterioration is analyzed in combination with the deterioration phenomenon of rock mass in the fluctuating zone of the reservoir area.The results show that the change of uniaxial compressive strength of marl in pH=3,5,7 solution is inversely proportional to the number of dry-wet cycles,and the cumulative deterioration degree Snvaries from 34.79%to 54.31%,and shows a trend of rapid increase,slow development and tends to be stable,while the range of peak stress deterioration is 8.79%~35.61%.The cohesion C,internal friction angleφand elastic modulus E of marl all decrease with the increase of the number of dry-wet cycles,and the damage deterioration is carried out in the progressive mode of circle layer.After the rock mass in the fluctuating zone of the reservoir area is subjected to the dry-wet cycle of acid solution,a large number of secondary cracks will sprout in the nearby rocks.with the advance of the number of cycles and the continuous accumulation of damage,the cracks gradually run through and expand to the inner layer of the slope.The expansion range and rate are related to the number of dry-wet cycles and the pH value of the solution.The above analysis conclusions and laws can provide scientific basis and theoretical methods for the prediction and emergency prevention of disasters such as collapse and instability of landslide,softening of dangerous rock base and water storage leakage in the reservoir area.