砂岩冻融损伤机制的理论分析和试验验证

发布时间：2019-06-15 16:27

【摘要】：由于岩石性质的复杂性和环境条件的多变性,岩石冻融损伤并不是单一机制造成的,应是各种机制共同作用的结果,但往往存在主导性的机制。首先对已有冻融损伤理论进行系统介绍,分析各自的适用条件。之后探讨多孔岩石(以砂岩为例)的孔隙结构对冻融损伤机制的控制性作用,并定义"特征冻融损伤单元"。利用热力学原理分析不同的冻结条件下砂岩内部可能发生的冻融损伤机制和主导机制。当冻结速率低时,毛细管机制(理论)和结晶压机制(理论)应在岩石的冻融损伤中起主导作用,而体积膨胀机制则受到抑制;当冻结速率高时,体积膨胀机制和静水压机制应在岩石的冻融损伤中起主导作用,而毛细管机制和结晶压机制则受到抑制。最后利用砂岩的冻融损伤试验——包括利用环境扫描电镜(ESEM)对砂岩孔隙结构及冻融损伤的微观观察和利用应变片对砂岩的冻胀变形过程的监测,对砂岩的冻融损伤机制进行了验证,试验结果与理论分析的结论相一致。
[Abstract]:Due to the complexity of rock properties and the variability of environmental conditions, rock freeze-thaw damage is not caused by a single mechanism, which should be the result of the interaction of various mechanisms, but there is often a dominant mechanism. Firstly, the existing freeze-thaw damage theory is introduced systematically, and the applicable conditions are analyzed. Then the control effect of pore structure of porous rocks (taking sandstone as an example) on freeze-thaw damage mechanism is discussed, and the "characteristic freeze-thaw damage element" is defined. The mechanism and main mechanism of freeze-thaw damage in sandstone under different freezing conditions are analyzed by thermodynamic principle. When the freezing rate is low, the capillary mechanism (theory) and crystallization pressure mechanism (theory) should play a dominant role in the freeze-thaw damage of rock, while the volume expansion mechanism should be suppressed. When the freezing rate is high, the volume expansion mechanism and hydrostatic pressure mechanism should play a dominant role in the freeze-thaw damage of rock, while the capillary mechanism and crystallization pressure mechanism should be suppressed. Finally, the freeze-thaw damage mechanism of sandstone is verified by using the freeze-thaw damage test of sandstone, including the microscopic observation of pore structure and freeze-thaw damage of sandstone by environmental scanning electron microscope (ESEM) and the monitoring of frost heave deformation process of sandstone by strain gauge. The experimental results are in good agreement with the conclusion of theoretical analysis.
【作者单位】：中国地质大学工程学院;中国地质大学教育部长江三峡库区地质灾害研究中心;
【基金】：国家自然科学基金青年基金项目(41302232);国家自然科学基金资助项目(41302228)~~
【分类号】：TU45

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