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深部原位应力环境钻进过程中岩心饼化成因机制:数值模拟与室内试验
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作者 李飞 高明忠 +6 位作者 叶思琪 谢晶 邓虎超 杨本高 刘军军 杨尊东 唐瑞烽 《Journal of Central South University》 SCIE EI CAS CSCD 2023年第10期3303-3321,共19页
深部岩体原位应力赋存状态一直是“黑箱”问题,基于岩心的应力测试技术已成为有效的解决手段之一。在深部原位应力环境钻进过程中时常出现岩心饼化现象,为了探索其在砂岩中的形成机制,利用PFC2D研究了不同原位应力条件下钻进过程中的裂... 深部岩体原位应力赋存状态一直是“黑箱”问题,基于岩心的应力测试技术已成为有效的解决手段之一。在深部原位应力环境钻进过程中时常出现岩心饼化现象,为了探索其在砂岩中的形成机制,利用PFC2D研究了不同原位应力条件下钻进过程中的裂纹分布和能量演化,获得了易发生岩心饼化的特定原位应力条件。应用自主开发的测试系统验证了实验室环境内岩心饼化所需的应力条件,并分析了岩心破裂特征、断面形貌与原位应力之间的关系。结果表明,原位应力越高,在钻进过程中岩石产生的拉裂纹越多,尤其是在孔壁和岩心根部,而岩心处裂纹从外表面向内部发展。更高的原位应力水平同样会导致更强的能量转换,进而引发岩石破裂。岩心饼化的形成需满足特定的应力条件。当径向应力(σ_(r))为最大主应力且保持45 MPa恒定、轴向应力(σa)为25 MPa或30 MPa时,岩心根部均会发生饼化现象。随着σ_(r)和σa之间差值或钻进深度的增加,岩心厚度减小,导致断面更光滑、分形维数更小,从而使岩心饼化现象更加显著。该研究可为科学阐明深部原位应力条件下岩心饼化的形成机制提供必要的技术和数据支持。 展开更多
关键词 深部岩体 原位应力 饼化形成机制 裂纹分布 能量演化 宏观破裂特征 断面形貌
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Optimization of Solid-Phase Extraction Conditions for Perfluorooctanoic Acid in Leachate
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作者 WANG Ying ZENG Xiaolan +3 位作者 YU Zhipeng JIN Jiyuan MI Ruidong SUN Yuan 《Wuhan University Journal of Natural Sciences》 CAS CSCD 2022年第4期341-348,共8页
In order to optimize the solid phase extraction(SPE)conditions of perfluorooctanoic acid(PFOA)in the raw leachate and treated leachate,the effects of activator properties,SPE cartridge,p H value,ionic strength,and elu... In order to optimize the solid phase extraction(SPE)conditions of perfluorooctanoic acid(PFOA)in the raw leachate and treated leachate,the effects of activator properties,SPE cartridge,p H value,ionic strength,and eluent properties were studied through single factor experiments.The optimal results of each single factor were obtained.Considering that the concentration of PFOA in the treated leachate is lower than that of the raw leachate,the SPE conditions of the treated leachate have been further optimized.Based on the above single-factor experiment,the main influencing factors were screened out as the volume of activator,ionic strength,and volume of eluent,and the three-factor threelevel response surface methodology(RSM)was optimized.The optimum SPE conditions of PFOA from treated landfill leachate were as follows:Activation of weak anion exchange(WAX)cartridge with 10 mL methanol,dosage of 600 mg KCl,6 m L 1%ammonia methanol eluted PFOA,the theory recovery rate is over95.67%.It has been verified that the error between the predicted value and the actual extraction recovery is small and has good repeatability. 展开更多
关键词 response surface methodology(RSM) box-behnken design perfluorooctanoic acid solid phase extraction detection method
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