【目的】注水和CO2会改变平直节理岩石的剪切特性,从而直接影响封存地层的稳定性。探究注水和注CO2对节理岩体剪切特性的影响规律。【方法】对平直节理砂岩进行干燥、注水和注CO2三种试验条件下的剪切试验,分析剪切强度随法向应力、注入流体类型和注入流体压力的变化规律。【结果】试验结果表明:平直节理砂岩在干燥、注水和注CO2三种试验条件下的剪切应力-剪切位移曲线都属于滑动破坏型曲线;注水/CO2会弱化平直节理岩石剪切强度,且水的弱化作用强于CO2;提出了平直节理岩石剪切强度与法向应力、注入流体类型和流体注入压力之间的经验公式,试验数据与理论数据的平均误差为5.69%.【结论】研究结果对预测砂岩在注入水/CO2后的剪切强度以及优化施工方案和提高施工安全性具有重要意义。

【Purposes】The injection of water and/or CO  alters the shear characteristics of  jointed rock, directly impacting the stability of the sequestered formation. Thus, the influence of wa⁃ ter injection and CO  injection on the shear characteristics of jointed rock mass is explored. 【Methods】  Shear tests were carried out on flat jointed sandstone under three test conditions : drying, water injec⁃ tion, and CO  injection. The changes of shear strength with confining pressure, injected fluid type,  and injection fluid pressure were investigated.【Findings】 The results indicate the following: The  shear stress-shear displacement curves for straight jointed sandstone under all three test conditions  (dry, CO  injection, and water injection) exhibit a sliding failure pattern; Water/CO  injection will  weaken the shear strength of straight jointed rock, and the weakening effect of water is stronger than  that of CO ; The empirical formula between shear strength and confining pressure, injection fluid  type, and fluid injection pressure is proposed. The average error between experimental and theoretical  data is 5.69%. 【Conclusions】This research work is of great significance for predicting the shear  strength of sandstone after water/CO  injection, optimizing the construction scheme, and improving  the construction safety.