干湿交替作用下砂岩劣化效应研究

发布时间：2018-08-06 10:16

【摘要】：水-岩相互作用是工程岩土体稳定性研究的重要内容,近年来一直是岩土工程相关学科研究的前沿领域。本文依托导师国家自然科学基金项目(No.41202229)“干湿交替作用下泥质砂岩强度劣化机理及损伤本构关系研究”,以云南某露天矿边坡砂岩为研究对象,以自然条件下砂岩干湿循环效应与微观结构发展演化规律为研究目的,通过室内砂岩强度、变形试验和微观测试,获取了干湿交替作用下砂岩强度和变形的变化规律,并从微观角度探讨了其产生干湿循环效应的作用机制,主要研究成果如下： (1)通过粉晶X衍射、薄片鉴定等手段测定了砂岩的矿物组成及含量；对干湿交替作用下的砂岩试样进行了吸水性试验,结果表明砂岩吸水率随干湿循环幅度的加大而增加,并建立了其与干湿循环次数之间的函数关系。 (2)对设定试验点的砂岩试样进行了单轴压缩变形试验,得到了砂岩在不同状态下的应力应变全过程曲线、抗压强度及变形指标,并对其随干湿循环次数的变化情况进行了系统的分析。 (3)进行了各关键试验点砂岩试样在单轴压缩变形下的声发射特征试验,结果表明,砂岩在干燥状态下的声发射活动较经干湿循环处理后要强烈的多,且随干湿循环次数的加大,声发射活动逐步减弱,同时产生了明显声发射的时间滞后现象。 (4)基于单轴压缩变形试验结果建立了考虑干湿循环效应砂岩的损伤统计本构关系,并对其进行了验证,结果表明所构建考虑干湿循环效应砂岩的损伤统计本构模型是合理的。 (5)开展了不同干湿循环作用下砂岩试样的直剪试验,试验结果表明砂岩抗剪强度与所受法向应力呈正相关关系,与干湿循环次数呈负相关关系,砂岩抗剪强度参数随干湿循环作用幅度的加大而降低,且粘聚力c对干湿循环效应的响应程度较内摩擦角φ要大。 (6)从微观角度出发,通过偏光显微镜观测不同状态砂岩试样内部孔隙结构、颗粒胶结方式等的变化情况。分析表明其内部结构随干湿循环幅度的加大亦有相应的改变。
[Abstract]:Water-rock interaction is an important part of the stability of rock and soil in engineering, and has been the frontier of geotechnical engineering in recent years. In this paper, based on the project of National Natural Science Foundation of China (No.41202229), "study on strength deterioration mechanism and damage constitutive relationship of argillaceous sandstone under dry-wet alternating action", a slope sandstone of an open-pit mine in Yunnan Province is taken as the research object. In order to study the dry-wet cycle effect and microstructure evolution law of sandstone under natural conditions, the variation law of sandstone strength and deformation under the alternating action of dry and wet is obtained through indoor sandstone strength, deformation test and microscopic test. The main results are as follows: (1) the mineral composition and content of sandstone were determined by powder X-ray diffraction and thin slice identification. The water absorption test of sandstone samples under the alternating action of dry and wet is carried out. The results show that the water absorption rate of sandstone increases with the increase of dry-wet cycle amplitude. The relationship between the number of dry and wet cycles is established. (2) uniaxial compression deformation tests are carried out on sandstone samples with set test points, and the stress-strain curves of sandstone under different conditions are obtained. The compressive strength and deformation index are systematically analyzed. (3) the acoustic emission characteristics of sandstone samples under uniaxial compression deformation at key test points are studied. The acoustic emission activity of sandstone in dry state is much stronger than that after dry and wet cycle treatment, and with the increase of dry and wet cycle times, the acoustic emission activity gradually weakens. At the same time, the time-lag phenomenon of acoustic emission is obvious. (4) based on the results of uniaxial compression deformation test, the statistical constitutive relationship of damage of sandstone considering dry-wet cycle effect is established and verified. The results show that the statistical constitutive model of sandstone damage considering dry-wet cycle effect is reasonable. (5) the direct shear tests of sandstone samples under different dry and wet cycles are carried out. The test results show that the shear strength of sandstone is positively correlated with the normal stress, and negatively correlated with the times of dry and wet cycles. The shear strength parameters of sandstone decrease with the increase of dry-wet cycle. The cohesive force c is more responsive to the dry and wet cycle effect than the internal friction angle 蠁. (6) from the microscopic point of view, the changes of pore structure and particle cementation mode of sandstone samples in different states are observed by polarizing microscope. The analysis shows that the internal structure changes with the increase of dry-wet cycle amplitude.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU45

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