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杨圣奇, 荆晓娇. 盐水干湿循环后砂岩物理力学特性试验研究[J]. 岩土工程学报, 2023, 45(10): 2165-2171. DOI: 10.11779/CJGE20220830
引用本文: 杨圣奇, 荆晓娇. 盐水干湿循环后砂岩物理力学特性试验研究[J]. 岩土工程学报, 2023, 45(10): 2165-2171. DOI: 10.11779/CJGE20220830
YANG Shengqi, JING Xiaojiao. Experimental study on physical and mechanical properties of sandstone after drying-wetting cycles of brine[J]. Chinese Journal of Geotechnical Engineering, 2023, 45(10): 2165-2171. DOI: 10.11779/CJGE20220830
Citation: YANG Shengqi, JING Xiaojiao. Experimental study on physical and mechanical properties of sandstone after drying-wetting cycles of brine[J]. Chinese Journal of Geotechnical Engineering, 2023, 45(10): 2165-2171. DOI: 10.11779/CJGE20220830

盐水干湿循环后砂岩物理力学特性试验研究

Experimental study on physical and mechanical properties of sandstone after drying-wetting cycles of brine

  • 摘要: 四川地区降雨蒸发、库区水位涨落等因素严重影响该地区边坡工程的稳定性。以盐水(5%NaCl)为浸泡溶液对不同干湿循环次数(0,5,10,20次)作用后饱和砂岩开展三轴压缩试验,分析其物理力学参数劣化规律,进而揭示盐水和干湿循环共同作用对饱和砂岩的损伤机理。研究结果表明:随着干湿循环次数增加,砂岩质量先增加后降低,而渗透率先降低后增加,干湿循环5次为试样质量变化率和渗透率的阈值;干湿循环作用后试样的峰值强度、内摩擦角、黏聚力以及弹性模量均小于干燥砂岩,并且随循环次数增加,试样峰值强度、黏聚力逐渐降低,而内摩擦角表现为先减小后增加;试样弹性模量随围压增加呈不同变化趋势;干湿循环对砂岩破坏模式无明显影响,即单轴和三轴压缩下试样分别呈轴向劈裂和剪切破坏。在干湿循环过程中,砂岩内部矿物颗粒逐渐流失,造成内部孔隙增大,是诱发岩石产生损伤的根本原因。

     

    Abstract: The factors such as rainfall evaporation and groundwater fluctuation in Sichuan Province of China seriously affect the stability of slope engineering in the area. The deterioration laws of physical and mechanical parameters of saturated sandstone after different drying-wetting cycles (0, 5, 10 and 20 times) in brine (5%NaCl) solution are analyzed by conducting the triaxial compression tests. The damage mechanisms of the brine and drying-wetting cycles on saturated sandstone are revealed. The results show that the sandstone mass increases first and then decreases, while the permeability decreases first and then increases with the increase of the number of drying-wetting cycles. The threshold value for the mass change rate and permeability is 5 drying-wetting cycles. The peak strength, internal friction angle, cohesion and elastic modulus of the samples after drying-wetting cycles are all smaller than those of the dry sandstone. The peak strength and cohesion of the samples decrease gradually, while the internal friction angle decreases first and then increases with the increase of the cycles. The elastic modulus of the samples shows different trends with the increase of the confining pressure. The drying-wetting cycles have no significant effects on the failure mode of the sandstone, that is, the samples under uniaxial and triaxial compressions exhibit axial splitting and shear failure respectively. In the process of drying-wetting cycles, the mineral particles in the sandstone are gradually lost, resulting in the increase of the internal pores, which is the fundamental cause of inducing rock damage.

     

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